Patent Application
20250093781
The present disclosure relates to removal of photoresist material in semiconductor fabrication, and more particularly to rework of patternable metal-containing photoresist material in semiconductor fabrication.
The fabrication of semiconductor devices, such as integrated circuits, is a multi-step process involving photolithography. In general, the process includes the deposition of material on a wafer, and patterning the material through lithographic techniques to form structural features (e.g., transistors and circuitry) of the semiconductor device. The steps of a typical photolithography process known in the art include: preparing the substrate; applying a photoresist, such as by spin coating, exposing the photoresist to light in a desired pattern, causing the exposed areas of the photoresist to become more or less soluble in a developer solution; developing by applying a developer solution to remove either the exposed or the unexposed areas of the photoresist; and subsequent processing to create features on the areas of the substrate from which the photoresist has been removed, such as by etching or material deposition.
The evolution of semiconductor design has created the need, and has been driven by the ability, to create ever smaller features on semiconductor substrate materials. This progression of technology has been characterized in “Moore's Law” as a doubling of the density of transistors in dense integrated circuits every two years. Indeed, chip design and manufacturing has progressed such that modern microprocessors may contain billions of transistors and other circuit features on a single chip. Individual features on such chips may be on the order of 22 nanometers (nm) or smaller, in some cases less than 10 nm.
One challenge in manufacturing devices having such small features is the ability to reliably and reproducibly create photolithographic masks having sufficient resolution. Current photolithography processes typically use 193 nm ultraviolet (UV) light to expose a photoresist. The fact that the light has a wavelength significantly greater than the desired size of the features to be produced on the semiconductor substrate creates inherent issues. Achieving feature sizes smaller than the wavelength of the light requires use of complex resolution enhancement techniques, such as multipatterning. Thus, there is significant interest and research effort in developing photolithographic techniques using shorter wavelength light, such as extreme ultraviolet radiation (EUV), having a wavelength of from 10 nm to 15 nm, e.g., 13.5 nm.
EUV photolithographic processes can present challenges, however, including low power output and loss of light during patterning. Traditional organic chemically amplified resists (CAR) similar to those used in 193 nm UV lithography have potential drawbacks when used in EUV lithography, particularly as they have low absorption coefficients in EUV region and the diffusion of photo-activated chemical species can result in blur or line edge roughness. Furthermore, in order to provide the etch resistance required to pattern underlying device layers, small features patterned in conventional CAR materials can result in high aspect ratios at risk of pattern collapse. Accordingly, there remains a need for improved EUV photoresist materials, having such properties as decreased thickness, greater absorbance, and greater etch resistance.
The background description provided herein is for the purpose of generally presenting the context of the present technology. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.
Provided herein is a method of removing metal-containing resist. The method includes providing in a process chamber a metal-containing resist on an underlayer of a semiconductor substrate, and exposing the metal-containing resist to an etch gas comprising a halide at a first elevated temperature to remove the metal-containing resist.
In some implementations, exposing the metal-containing resist to the etch gas comprises selectively removing the metal-containing resist relative to the underlayer. In some implementations, exposing the metal-containing resist to the etch gas is performed without exposure to plasma. In some implementations, exposing the metal-containing resist to the etch gas is performed with exposure to plasma. In some implementations, the method further includes exposing the underlayer and residual halides to removal gas to remove the underlayer and the residual halides after removing the metal-containing resist, where the removal gas includes an oxidizing gas or hydrogen gas at a second elevated temperature greater than the first elevated temperature. In some implementations, the method further includes exposing the underlayer and residual halides to plasma to remove the underlayer and the residual halides after removing the metal-containing resist, where the plasma includes ions and/or radicals of an oxidizing gas or hydrogen gas. In some implementations, the method further includes exposing the underlayer to plasma to treat a surface of the underlayer after removing the metal-containing resist. In some implementations, the method further includes exposing the semiconductor substrate to an aqueous solution of dilute hydrofluoric acid (dHF), and exposing the semiconductor substrate to an aqueous solution of dilute hydrochloric acid (dHCl) or a cleaning solution comprising ammonium hydroxide (NH4OH) and hydrogen peroxide (H2O2). In some implementations, the metal-containing resist is a photopatterned metal-containing EUV resist. In some implementations, the etch gas comprises hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen bromide (HBr), hydrogen iodide (HI), hydrogen gas and fluorine gas (H2+F2), hydrogen gas and chlorine gas (H2+Cl2), hydrogen gas and bromine gas (H2+Br2), hydrogen gas and iodide gas (H2+I2), or bromine trichloride (BC3). In some implementations, the first elevated temperature is between about 60° C. and about 250° C. In some implementations, a chamber pressure during exposure of the metal-containing resist to the etch gas is between about 100 mTorr and about 2000 mTorr, where a flow rate of the etch gas during exposure of the metal-containing resist to the etch gas is between about 100 sccm and about 5000 sccm. In some implementations, the underlayer comprises spin-on glass (SOG), spin-on carbon (SOC), amorphous or crystalline carbon, or silicon oxynitride (SiON). In some implementations, the method further includes conformally depositing a mask layer on the metal-containing resist, and removing a portion of the mask layer to expose a top surface of the metal-containing resist, where exposing the metal-containing resist to the etch gas selectively removes the metal-containing resist relative to the mask layer. In some implementations, exposing the metal-containing resist to the etch gas at the first elevated temperature comprises exposing a frontside of the semiconductor substrate to light from a plurality of light-emitting diodes (LEDs).
Also provided herein is a method of removing metal-containing resist. The method includes providing in a process chamber a metal-containing resist on an underlayer of a semiconductor substrate, and exposing the metal-containing resist to at least an aqueous solution of a dilute acid to remove the metal-containing resist.
In some implementations, exposing the metal-containing resist to at least the aqueous solution of the dilute acid comprises exposing the semiconductor substrate to an aqueous solution of dilute hydrofluoric acid (dHF), and exposing the semiconductor substrate to an aqueous solution of dilute hydrochloric acid (dHCl) or a cleaning solution comprising ammonium hydroxide (NH4OH) and hydrogen peroxide (H2O2). In some implementations, the metal-containing resist is a photopatterned metal-containing EUV resist. In some implementations, exposing the metal-containing resist to at least the aqueous solution of the dilute acid selectively removes the metal-containing resist relative to the underlayer. In some implementations, the underlayer comprises spin-on glass (SOG), spin-on carbon (SOC), amorphous or crystalline carbon, or silicon oxynitride (SiON). In some implementations, exposing the metal-containing resist to at least the aqueous solution of the dilute acid comprises exposing a frontside and a backside of the semiconductor substrate to the aqueous solution of the dilute acid. In some implementations, the method further includes exposing the underlayer to plasma to treat a surface of the underlayer after removing the metal-containing resist.
Reference is made herein in detail to specific embodiments of the disclosure. Examples of the specific embodiments are illustrated in the accompanying drawings. While the disclosure will be described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the disclosure to such specific embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. The present disclosure may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail so as to not unnecessarily obscure the present disclosure.
Patterning of thin films in semiconductor processing is often an important step in the fabrication of semiconductors. Patterning involves lithography. In conventional photolithography, such as 193 nm photolithography, patterns are printed by emitting photons from a photon source onto a mask and printing the pattern onto a photosensitive photoresist, thereby causing a chemical reaction in the photoresist that, after development, removes certain portions of the photoresist to form the pattern.
Advanced technology nodes (as defined by the International Technology Roadmap for Semiconductors) include nodes 22 nm, 16 nm, and beyond. In the 16 nm node, for example, the width of a typical via or line in a Damascene structure is typically no greater than about 30 nm. Scaling of features on advanced semiconductor integrated circuits (ICs) and other devices is driving lithography to improve resolution.
Extreme ultraviolet (EUV) lithography can extend lithography technology by moving to smaller imaging source wavelengths than would be achievable with conventional photolithography methods. EUV light sources at approximately 10-20 nm, or 11-14 nm wavelength, for example 13.5 nm wavelength, can be used for leading-edge lithography tools, also referred to as scanners. The EUV radiation is strongly absorbed in a wide range of solid and fluid materials including quartz and water vapor, and so operates in a vacuum.
EUV lithography makes use of EUV resists that are patterned to form masks for use in etching underlying layers. EUV resists may be polymer-based chemically amplified resists (CARs) produced by liquid-based spin-on techniques. An alternative to CARs is directly photopatternable metal oxide-containing films, such as those available from Inpria Corp. (Corvallis, OR) and described, for example, in US Patent Publications US 2017/0102612, US 2016/021660, and US 2016/0116839, incorporated by reference herein at least for their disclosure of photopatternable metal oxide-containing films. Such films may be produced by spin-on techniques or dry vapor-deposited. The metal oxide-containing film can be patterned directly (i.e., without the use of a separate photoresist) by EUV exposure in a vacuum ambient providing sub-30 nm patterning resolution, for example as described in U.S. Pat. No. 9,996,004, issued Jun. 12, 2018 and titled EUV PHOTOPATTERNING OF VAPOR-DEPOSITED METAL OXIDE-CONTAINING HARDMASKS, and/or in International Patent Application No. PCT/US2019/31618, filed May 9, 2019, and titled METHODS FOR MAKING EUV PATTERNABLE HARD MASKS, the disclosures of which at least relating to the composition, deposition, and patterning of directly photopatternable metal oxide films to form EUV resist masks is incorporated by reference herein. Generally, the patterning involves exposure of the EUV resist with EUV radiation to form a photo-pattern in the resist, followed by development to remove a portion of the resist according to the photo-pattern to form the mask.
It should also be understood that the while present disclosure relates to lithographic patterning techniques and materials exemplified by EUV lithography, it is also applicable to other next generation lithographic techniques. In addition to EUV, which includes the standard 13.5 nm EUV wavelength currently in use and development, the radiation sources most relevant to such lithography are DUV (deep-UV), which generally refers to use of 248 nm or 193 nm excimer laser sources, X-ray, which formally includes EUV at the lower energy range of the X-ray range, as well as e-beam, which can cover a wide energy range. The specific methods may depend on the particular materials and applications used in the semiconductor substrate and ultimate semiconducting device. Thus, the methods described in this application are merely exemplary of the methods and materials that may be used in present technology.
Directly photopatternable EUV resists may be composed of or contain metals and/or metal oxides mixed within organic components. The metals/metal oxides are highly promising in that they can enhance the EUV photon adsorption and generate secondary electrons and/or show increased etch selectivity to an underlying film stack and device layers. These resists can be developed using a wet (solvent) approach or dry approach.
Patterned photoresists are used as masks to form patterns on a substrate during etching to protect selected areas of the substrate. After development, an inspection such as an after-develop-inspection (ADI) is performed. The inspection can ensure that the photolithography process has been performed correctly and within a specified tolerance. In some instances, the photoresists may be misaligned, may have unacceptable critical dimensions, or may embody defective patterns. A defective photoresist pattern or misaligned photoresist pattern can be detrimental to semiconductor substrate processing and even lead to device failure. Rather than discarding the entire substrate, the photoresist can be stripped, removed, or reworked when there are misalignment or other errors in the photoresist.
There are several different types of photoresist rework techniques. One method may involve burning photoresist from a substrate by an oxygen plasma, which is called oxygen plasma ashing. However, sidewall polymers and inorganic substances may still be present after the ashing process is complete. Another method may involve wet stripping, where an organic solvent may be applied. Or, wet stripping can employ a solution such as sulfuric acid (H2SO4) before metal layers, and an amine solution after metal layers. In some instances, photoresist removal may involve oxygen plasma ashing followed by wet stripping. These processes may have numerous shortcomings for photoresist rework. For example, such conventional photoresist reworking processes may have a long cycle time and large cost. Furthermore, these conventional photoresist reworking processes may not be suitable for removal of metal-containing photoresist such as photopatternable EUV resist. While the conventional photoresist removal techniques may effectively remove traditional photoresists such as spin-coated photoresists, such conventional photoresist removal techniques including oxygen plasma ashing, organic solvents, sulfuric acid solutions, etc. do not effectively remove metal-containing photoresists.
According to various aspects of the present disclosure, a photopatternable metal-containing resist is provided on a semiconductor substrate and removed using an etch gas at an elevated temperature. The metal-containing resist may be removed in a thermal environment without exposure to plasma (i.e., plasma-free etch gas). In some embodiments, however, the metal-containing resist may be removed in the thermal environment with exposure to plasma to accelerate removal of the metal-containing resist. The elevated temperature may be between about 60° C. and about 250° C. The metal-containing resist may include a photopatternable metal-containing EUV resist. The etch gas may include a halide such as hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen bromide (HBr), hydrogen iodide (HI), hydrogen gas and fluorine gas (H2+F2), hydrogen gas and chlorine gas (H2+Cl2), hydrogen gas and bromine gas (H2+Br2), hydrogen gas and iodide gas (H2+I2), and/or bromine trichloride (BCl3). In some embodiments, the metal-containing resist is deposited on an underlayer, where exposing the metal-containing resist to the etch gas selectively removes the metal-containing resist relative to the underlayer. In some embodiments, the underlayer and residual halides may be removed by an oxidizing gas or hydrogen gas at a higher elevated temperature. Or, the underlayer and residual halides may be removed by plasma, where the plasma can include ions and/or radicals of an oxidizing gas or hydrogen gas. The underlayer may include spin-on glass (SOG), spin-on carbon, amorphous or crystalline carbon, or silicon oxynitride (SiON).
According to various aspects of the present disclosure, a photopatternable metal-containing resist is provided on a semiconductor substrate and removed using a wet process. The wet process may include at least an aqueous solution of a dilute acid to remove the metal-containing resist. Exposure to an aqueous solution of dilute acid may include exposure to dilute hydrofluoric acid (dHF) and exposure to dilute hydrochloric acid (dHCl), or exposure to dilute hydrofluoric acid and exposure to a cleaning solution comprising ammonium hydroxide (NH4OH) and hydrogen peroxide (H2O2). The metal-containing resist may include a photopatternable metal-containing EUV resist. In some embodiments, the metal-containing resist is deposited on an underlayer, where exposing the metal-containing resist to the aqueous solution of dilute acid selectively removes the metal-containing resist relative to the underlayer. The underlayer may include spin-on glass, spin-on carbon, amorphous or crystalline carbon, or silicon oxynitride.
At block 102 of the process 100, a layer of photoresist is deposited. This may be either a dry deposition process such as a vapor deposition process or a wet process such as a spin-on deposition process.
The photoresist may be a metal-containing EUV resist. An EUV-sensitive metal or metal oxide-containing film may be deposited on a semiconductor substrate by any suitable technique, including wet (e.g., spin-on) or dry (e.g., CVD) deposition techniques. For example, described processes have been demonstrated for EUV photoresist compositions based on organotin oxides, being applicable to both commercially spin-coatable formulations (e.g., such as are available from Inpria Corp, Corvallis, OR) and formulations applied using dry vacuum deposition techniques, further described below.
Semiconductor substrates may include any material construct suitable for photolithographic processing, particularly for the production of integrated circuits and other semiconducting devices. In some implementations, semiconductor substrates are silicon wafers. Semiconductor substrates may be silicon wafers upon which features have been created (“underlying features”), having an irregular surface topography. As referred to herein, the “surface” is a surface onto which a film of the present disclosure is to be deposited or that is to be exposed to EUV during processing. Underlying features may include regions in which material has been removed (e.g., by etching) or regions in which materials have been added (e.g., by deposition) during processing prior to conducting a method of this disclosure. Such prior processing may include methods of this disclosure or other processing methods in an iterative process by which two or more layers of features are formed on the substrate.
EUV-sensitive thin films may be deposited on the semiconductor substrate, such films being operable as resists for subsequent EUV lithography and processing. Such EUV-sensitive thin films comprise materials which, upon exposure to EUV, undergo changes, such as the loss of bulky pendant substituents bonded to metal atoms in low density M-OH rich materials, allowing their crosslinking to denser M-O-M bonded metal oxide materials. Through EUV patterning, areas of the film are created that have altered physical or chemical properties relative to unexposed areas. These properties may be exploited in subsequent processing, such as to dissolve either unexposed or exposed areas, or to selectively deposit materials on either the exposed or unexposed areas. In some implementations, the unexposed film has a more hydrophobic surface than the exposed film under the conditions at which such subsequent processing is performed. For example, the removal of material may be performed by leveraging differences in chemical composition, density and cross-linking of the film. Removal may be by wet processing or dry processing, as further described below.
The thin films are, in various implementations, organometallic materials, for example organotin materials comprising tin oxide, or other metal oxide materials/moieties. The organometallic compounds may be made in a vapor phase reaction of an organometallic precursor with a counter reactant. In various implementations, the organometallic compounds are formed through mixing specific combinations of organometallic precursors having bulky alkyl groups or fluoroalkyl groups with counter-reactants and polymerizing the mixture in the vapor phase to produce a low-density, EUV-sensitive material that deposits onto the semiconductor substrate.
In various implementations, organometallic precursors comprise at least one alkyl group on each metal atom that can survive the vapor-phase reaction, while other ligands or ions coordinated to the metal atom can be replaced by the counter-reactants. Organometallic precursors include those of the formula.
MaRbLc (Formula 1)
Organometallic precursors may be any of a wide variety of candidate metal-organic precursors. For example, where M is tin, such precursors include t-butyl tris(dimethylamino) tin, i-butyl tris(dimethylamino) tin, n-butyl tris(dimethylamino) tin, sec-butyl tris(dimethylamino) tin, i-propyl(tris)dimethylamino tin, n-propyl tris(dimethylamino) tin, ethyl tris(dimethylamino) tin and analogous alkyl(tris)(t-butoxy) tin compounds such as t-butyl tris(t-butoxy) tin. In some implementations, the organometallic precursors are partially fluorinated.
Counter-reactants have the ability to replace the reactive moieties, ligands or ions (e.g., L in Formula 1, above) so as to link at least two metal atoms via chemical bonding. Counter-reactants can include water, peroxides (e.g., hydrogen peroxide), di- or polyhydroxy alcohols, fluorinated di- or polyhydroxy alcohols, fluorinated glycols, and other sources of hydroxyl moieties. In various implementations, a counter-reactant reacts with the organometallic precursor by forming oxygen bridges between neighboring metal atoms. Other potential counter-reactants include hydrogen sulfide and hydrogen disulfide, which can crosslink metal atoms via sulfur bridges.
The thin films may include optional materials in addition to an organometallic precursor and counter-reactants to modify the chemical or physical properties of the film, such as to modify the sensitivity of the film to EUV or enhancing etch resistance. Such optional materials may be introduced, such as by doping during vapor phase formation prior to deposition on the semiconductor substrate, after deposition of the thin film, or both. In some implementations, a gentle remote H2 plasma may be introduced so as to replace some Sn-L bonds with Sn—H, which can increase reactivity of the resist under EUV.
In various implementations, the EUV-patternable films are made and deposited on the semiconductor substrate using vapor deposition equipment and processes among those known in the art. In such processes, the polymerized organometallic material is formed in vapor phase or in situ on the surface of the semiconductor substrate. Suitable processes include, for example, chemical vapor deposition (CVD), atomic layer deposition (ALD), and ALD with a CVD component, such as a discontinuous, ALD-like process in which metal precursors and counter-reactants are separated in either time or space. In some implementations, the EUV-patternable films are made and deposited on the semiconductor substrate using wet deposition equipment and processes among those known in the art. For example, the organometallic material is formed by spin-coating on the surface of the semiconductor substrate. Regardless, photoresist rework and other associated lithography operations may be subsequently applied on metal-containing EUV resist irrespective of how the metal-containing EUV resist is deposited.
The thickness of the EUV-patternable film formed on the surface of the semiconductor substrate may vary according to the surface characteristics, materials used, and processing conditions. In various implementations, the film thickness may range from 0.5 nm to 100 nm, and may be a sufficient thickness to absorb most of the EUV light under the conditions of EUV patterning. The EUV-patternable film may be able to accommodate absorption equal to or greater than 30%, thereby having significantly fewer EUV photons available towards the bottom of the EUV-patternable film. Higher EUV absorption leads to more cross-linking and densification near the top of an EUV-exposed film compared to the bottom of the EUV-exposed film. Though efficient utilization of EUV photons may occur with EUV-patternable films having higher overall absorption, it will be understood that in some instances, the EUV-patternable film may be less than about 30%. For comparison, the maximum overall absorption of most other resist films is less than 30% (e.g., 10% or less, or 5% or less) so that the resist material at the bottom of the resist film is sufficiently exposed. In some implementations, the film thickness is from 10 nm to 40 nm or from 10 nm to 20 nm. Moreover, as discussed above, the deposited films may closely conform to surface features, providing advantages in forming masks over substrates, such as substrates having underlying features, without “filling in” or otherwise planarizing such features.
At block 114 of the process 100, a photoresist rework is performed after deposition of the metal-containing EUV resist thin film at block 102 of the process 100. Removal of the metal-containing EUV resist thin film may take place before patterning of the metal-containing EUV resist thin film. Removal of the metal-containing EUV resist thin film may occur in a purely thermal environment or using a wet process. In some embodiments, deposition and removal of the metal-containing EUV resist film may be performed in the same process chamber. However, it will be understood that photoresist rework may be performed in a different process chamber than the deposition operation in some implementations. In fact, the photoresist rework may be performed subsequent to a bevel edge and/or backside clean, bake, exposure, development, or etch operation, which may or may not be the same as the deposition chamber.
It is possible that the deposited EUV resist materials being removed are generally composed of Sn, O, and C, but film strip and photoresist rework can be extended to films of other metal oxide resists and materials.
At block 104, an optional cleaning process is performed to clean a backside and/or bevel edge of the semiconductor substrate. The backside and/or bevel edge clean may non-selectively etch EUV resist film to equally remove film with various levels of oxidation or crosslinking on the substrate backside and bevel edge. During application of the EUV-patternable film, either by wet deposition processing or dry deposition processing, there may be some unintended deposition of resist material on the substrate bevel edge and/or backside. The unintended deposition may lead to undesirable particles later moving to a top surface of the semiconductor substrate and becoming particle defects. Additionally, this bevel edge and backside deposition can cause downstream processing problems, including contamination of the patterning (scanner) and development tools. Removal of this bevel edge and backside deposition can be done by wet cleaning or dry cleaning techniques.
By way of an example, the substrate bevel edge and/or backside clean may be a dry clean process. In some implementations, the dry clean process involves a vapor and/or plasma having one or more of the following gases: HBr, HCl, BC3, SOCl2, Cl2, BBr3, H2, O2, PCl3, CH4, methanol, ammonia, formic acid, NF3, HF. In some implementations, the dry clean process may use the same chemistries as a dry development process. For the bevel edge and/or backside clean process, the vapor and/or the plasma has to be limited to a specific region of the substrate to ensure that only the backside and the bevel are removed, without any film degradation on a frontside of the substrate.
Process conditions may be optimized for bevel edge and/or backside clean. In some implementations, higher temperature, higher pressure, and/or higher reactant flow may lead to increased etch rate. Suitable process conditions for a dry bevel edge and backside clean may be: reactant flow of 100-10000 sccm (e.g., 500 sccm HCl, HBr, HI, or H2 and Cl2 or Br2, BCl3 or H2, or other halogen-containing compound), temperature of 20° C. to 140° C. (e.g., 80° C.), pressure of 20-1000 mTorr (e.g., 100 mTorr) or pressure of 50-765 Torr (e.g., 760 Torr), plasma power of 0 to 500 W at high frequency (e.g., 13.56 MHz), and for a time of about 10 to 20 seconds, dependent on the photoresist film and composition and properties. Bevel and/or backside clean may be accomplished using a Coronus® tool available from Lam Research Corporation, Fremont, CA, though a wider range of process conditions may be used according to the capabilities of the processing reactor.
Bevel edge and/or backside clean may alternatively be extended to a full photoresist removal or photoresist “rework” as described herein where an applied EUV photoresist is removed and the semiconductor substrate prepared for photoresist reapplication, such as when the original photoresist is damaged or otherwise defective. Photoresist rework is typically accomplished without damaging the underlying semiconductor substrate, so an oxygen-based etch is usually avoided. Instead, organic vapor chemistries or variants of halogen-containing chemistries as described herein may be used. It will be understood that the photoresist rework operation may be applied at any stage during the process 100. Thus, the photoresist rework operation may be applied after deposition, after bevel edge and/or backside clean, after PAB treatment, after EUV exposure, after PEB treatment, after development, or after hard bake. In some implementations, the photoresist rework may be performed for non-selective removal of exposed and unexposed regions of the photoresist but selective to an underlayer.
At block 114 of the process 100, a photoresist rework is performed after a bevel edge and/or backside clean at block 104 of the process 100. This allows for bevel edge and/or backside clean and photoresist rework to be performed in the same process chamber. However, it will be understood that the photoresist rework may be performed in a different process chamber than the bevel edge and/or backside clean in some implementations.
At block 106 of the process 100, an optional post-application bake (PAB) is performed after deposition of the metal-containing EUV resist film and prior to EUV exposure. The PAB treatment may involve a combination of thermal treatment, chemical exposure, and moisture to increase the EUV sensitivity of the metal-containing EUV resist film, reducing the EUV dose to develop a pattern in the metal-containing EUV resist film. The PAB treatment temperature may be tuned and optimized for increasing the sensitivity of the metal-containing EUV resist film. For example, the treatment temperature may be between about 90° C. and about 200° C. or between about 150° C. and about 190° C. In some implementations, the PAB treatment may be conducted with a pressure between atmospheric and vacuum, and a treatment duration of about 1 to 15 minutes, for example about 2 minutes. In some implementations, the PAB treatment is conducted at a temperature between about 100° C. to 230° C. for about 1 minute to 2 minutes.
At block 114 of the process 100, a photoresist rework operation may be performed after the PAB treatment at block 106 of the process 100. This allows for bake and photoresist rework to be performed in the same process chamber. However, it will be understood that the photoresist rework may be performed in a different process chamber than the PAB treatment in some implementations.
At block 108 of the process 100, the metal-containing EUV resist film is exposed to EUV radiation to develop a pattern. Generally speaking, the EUV exposure causes a change in the chemical composition and cross-linking in the metal-containing EUV resist film, creating a contrast in etch selectivity that can be exploited for subsequent development.
The metal-containing EUV resist film may then be patterned by exposing a region of the film to EUV light, typically under relatively high vacuum. EUV devices and imaging methods among those useful herein include methods known in the art. In particular, as discussed above, exposed areas of the film are created through EUV patterning that have altered physical or chemical properties relative to unexposed areas. For example, in exposed areas, metal-carbon bond cleavage may occur, as through a beta-hydride elimination, leaving behind reactive and accessible metal hydride functionality that can be converted to hydroxide and cross-linked metal oxide moieties via metal-oxygen bridges during a subsequent post-exposure bake (PEB) step. This process can be used to create chemical contrast for development as a negative tone resist. In general, a greater number of beta-H in the alkyl group results in a more sensitive film. This can also be explained as weaker Sn—C bonding with more branching. Following exposure, the metal-containing EUV resist film may be baked, so as to cause additional cross-linking of the metal oxide film. The difference in properties between exposed and unexposed areas may be exploited in subsequent processing, such as to dissolve unexposed areas or to deposit materials on the exposed areas. For example the pattern can be developed using a suitable method to form a metal oxide-containing mask.
In particular, in various implementations, the hydrocarbyl-terminated tin oxide present on the surface is converted to hydrogen-terminated tin oxide in the exposed region(s) of an imaging layer, particularly when the exposure is performed in a vacuum using EUV. However, removing exposed imaging layers from vacuum into air, or the controlled introduction of oxygen, ozone, H2O2, or water, can result in the oxidation of surface Sn—H into Sn—OH. The difference in properties between exposed and unexposed regions may be exploited in subsequent processing, such as by reacting the irradiated region, the unirradiated region, or both, with one or more reagents to selectively add material to or remove material from the imaging layer.
Without limiting the mechanism, function or utility of present technology, EUV exposure, for example, at doses of from 10 mJ/cm2 to 100 mJ/cm2 results in the cleavage of Sn—C bonds resulting in loss of the alkyl substituent, alleviating steric hindrance and allowing the low-density film to collapse. In addition, reactive metal-H bond generated in the beta-hydride elimination reactions can react with neighboring active groups such as hydroxyls in the film, leading to further cross-linking and densification, and creating chemical contrast between exposed and unexposed region(s).
Following exposure of the metal-containing EUV resist film to EUV light, a photopatterned metal-containing EUV resist is provided. The photopatterned metal-containing EUV resist includes EUV-exposed and unexposed regions.
At block 114 of the process 100, a photoresist rework operation may be performed after the EUV exposure at block 108 of the process 100. This allows for photoresist rework to take place after forming photopatterned metal-containing EUV resist. It will be understood that the photoresist rework may be performed in a different process chamber than EUV exposure in some implementations.
At block 110 of the process 100, an optional post-exposure bake (PEB) is performed to further increase contrast in etch selectivity of the photopatterned metal-containing EUV resist. The photopatterned metal-containing EUV resist can be thermally treated in the presence of various chemical species to facilitate cross-linking of the EUV-exposed regions or simply baked on a hot plate in ambient air, for example between 100° C. and 250° C. for between one and five minutes (e.g., 190° C. for two minutes).
In various implementations, a bake strategy involves careful control of the bake ambient, introduction of reactive gases, and/or careful control of the ramping rate of the bake temperature. Examples of useful reactive gases include e.g., air, H2O, H2O2 vapor, CO2, CO, O2, O3, CH4, CH3OH, N2, H2, NH3, N2O, NO, alcohol, acetyl acetone, formic acid, Ar, He, or their mixtures. The PEB treatment is designed to (1) drive complete evaporation of organic fragments that are generated during EUV exposure and (2) oxidize any Sn—H, Sn—Sn, or Sn radical species generated by EUV exposure into metal hydroxide, and (3) facilitate cross-linking between neighboring Sn—OH groups to form a more densely crosslinked SnO2-like network. The bake temperature is carefully selected to achieve optimal EUV lithographic performance. Too low a PEB temperature would lead to insufficient cross-linking, and consequently less chemical contrast for development at a given dose. Too high a PEB temperature would also have detrimental impacts, including severe oxidation and film shrinkage in the unexposed region (the region that is removed by development of the patterned film to form the mask in this example), as well as, undesired interdiffusion at the interface between the photopatterned metal-containing EUV resist and an underlayer, both of which can contribute to loss of chemical contrast and an increase in defect density due to insoluble scum. The PEB treatment temperature may be between about 100° C. and about 300° C., between about 170° C. and about 290° C., or between about 200° C. and about 240° C. In some implementations, the PEB treatment may be conducted with a pressure between atmospheric and vacuum, and a treatment duration of about 1 to 15 minutes, for example about 2 minutes. In some implementations, PEB thermal treatment may be repeated to further increase etch selectivity.
At block 114 of the process 100, a photoresist rework operation may be performed after the PEB treatment at block 110 of the process 100. This allows for bake and photoresist rework to be performed in the same process chamber. However, it will be understood that the photoresist rework may be performed in a different process chamber than the PEB treatment in some implementations.
At block 112 of the process 100, the photopatterned metal-containing EUV resist is developed to form a resist mask. In various implementations, the exposed regions are removed (positive tone) or the unexposed regions are removed (negative tone). In some implementations, development may include selective deposition on either the exposed or unexposed regions of the photopatterned metal-containing EUV resist, followed by an etching operation. In some implementations, development may be done with exposure to dry chemistries. The development may be done without striking a plasma in some implementations. Or, development may be done with flows of dry chemistries activated in a remote plasma source or activated by exposure to remote UV radiation. The photoresist for development may include an element selected from the group consisting of tin, hafnium, tellurium, bismuth, indium, antimony, iodine, and germanium. The element may have a high patterning radiation-absorption cross-section. In some implementations, the element may have a high EUV-absorption cross-section. In some implementations, the metal-containing EUV resist may have an overall absorption greater than 30%. In an all-dry lithography process, this provides more efficient utilization of EUV photons, enabling development of thicker and more EUV-opaque resists.
Examples of processes for development involve an organotin oxide-containing EUV-sensitive photoresist thin film (e.g., 10-40 nm thick, such as 20 nm), subjected to a EUV exposure dose and post-exposure bake, and then developed. The photoresist film may be, for example, deposited based on a gas phase reaction of an organotin precursor such as isopropyl(tris)(dimethylamino)tin and water vapor, or may be a spin-on film comprising tin clusters in an organic matrix.
At block 114 of the process 100, a photoresist rework operation may be performed after development at block 112 of the process 100. This allows for development and photoresist rework to be performed in the same process chamber. However, it will be understood that the photoresist rework may be performed in a different process chamber than development in some implementations.
At block 202 of the process 200, a metal-containing resist is provided on an underlayer of a semiconductor substrate in a process chamber. The metal-containing resist may be deposited on the surface of the semiconductor substrate. The metal-containing resist is dry or wet deposited on the semiconductor substrate. In some implementations, the metal-containing resist is provided as a photopatterned metal-containing resist after undergoing development. In some implementations, the metal-containing resist is provided as a positive tone or negative tone resist having EUV-exposed and EUV-unexposed regions after EUV exposure. In some implementations, the metal-containing resist is provided as photopatternable metal-containing resist prior to EUV exposure and development. In some implementations, the metal-containing resist is metal-containing EUV resist, where the metal-containing EUV resist may be an organo-metal oxide or organo-metal-containing film. The composition of metal-containing resist material may be described, for example, in International Patent Application No. PCT/US2019/31618, filed May 9, 2019, incorporated by reference herein in its entirety and for all purposes. Methods include those where polymerized organometallic materials are produced in the vapor phase and deposited on the semiconductor substrate. For example, an element in the metal-containing resist material may be selected from a group consisting of: tin, hafnium, tellurium, bismuth, indium, antimony, iodine, germanium, and combinations thereof.
The metal-containing resist is disposed on an underlayer of the substrate. The underlayer may include a device layer to be patterned using the metal-containing resist as a mask. After development of the metal-containing resist, the underlayer may be etched according to a pattern of the metal-containing resist. In some implementations, the underlayer includes spin-on glass (SOG), spin-on carbon (SOC), amorphous or crystalline carbon, or silicon oxynitride (SiON). For example, the underlayer may include carbon such as carbon deposited by plasma-enhanced chemical vapor deposition (PECVD). The metal-containing resist is composed of a different material than the underlayer so that a subsequent photoresist rework may be selective to the metal-containing resist relative to the underlayer.
At block 204 of the process 200, the metal-containing resist is exposed to an etch gas comprising a halide at a first elevated temperature to remove the metal-containing resist. In some embodiments, photoresist rework is performed in a thermal environment without any exposure to plasma. In some alternative embodiments, photoresist rework is performed in a thermal environment with exposure to plasma to accelerate removal of the metal-containing resist. The etch gas for photoresist rework includes a halogen-containing gas. In some embodiments, the metal-containing resist is selectively removed relative to the underlayer. In some other embodiments, the metal-containing resist and the underlayer are removed together with exposure to the etch gas at the first elevated temperature.
Photoresist rework may involve vapors of halogens such as a vapor of boron trichloride (BC3), hydrogen gas (H2) mixed with fluorine gas (F2), chlorine gas (Cl2), bromine gas (Br2), or iodine gas (I2), or a vapor of a hydrogen halide such as hydrogen fluoride (HF), hydrogen chloride (HCl), hydrogen bromide (HBr), or hydrogen iodide (HI). However, such vapors may leave a residue or scum after development. The residue may include residual etch byproduct adsorbed on surfaces of the semiconductor substrate. For example, the vapors of halogens may react with moisture or oxygen to forming residual etch byproducts that are difficult to remove. In some cases, the residue may include high metal concentrations or particles or clusters of metal oxide (e.g., SnOx) that can contaminate downstream processing tools. As photoresist rework proceeds, the clusters of metal oxide may become more concentrated. Clusters of metal oxide are generally difficult to remove. And because the residue may be difficult to remove and not readily volatile, a separate plasma step or separate chamber with plasma capability may be necessary. Otherwise, high temperature swings are performed to cause the residue to volatilize. In some embodiments, the etch gas for photoresist rework includes an organic vapor such as an organic acid. In some implementations, the organic acid includes a carboxylic acid. In some implementations, the organic acid includes trifluoroacetic acid (CF3COOH), hexafluoro-acetylacetone (CF3CCH2CCF3), trifluoroacetic acid anhydride ((CF3CO)2O), acetic acid anhydride ((CH3CO)2O), trichloroacetic acid (CC3COOH), mono-fluoroacetic acid (CFH2COOH), di-fluoroacetic acid (CF2HCOOH), a mixed halide acetic acid such as chloro-difluoro-acetic acid, a sulfur-containing analogue of acetic acid, thioacetic acid (CH3COSH), or thioglycolic acid (HSCH2CO2H).
Photoresist rework of the present disclosure may be performed in a plasma-free thermal process. This means that the process chamber for photoresist rework may be without plasma capability. By eliminating plasma exposure, this avoids plasma damage to the semiconductor substrate and can significantly reduce cost and increase throughput. Furthermore, internal surfaces of the process chamber may be made of materials that do not have to be resistant to plasma as well as resistant to vapors of halogens such as hydrogen halides. By applying a plasma-free thermal approach, productivity can be significantly improved as multiple wafers can be batch developed, at the same time in a low-cost thermal vacuum chamber/oven. However, in some implementations, the thermal photoresist rework process may be followed by exposure to plasma. Subsequent exposure to plasma may occur for desorption, descumming, treatment, or other processing operations. Alternatively, in some implementations, the thermal photoresist rework process may be accompanied by exposure to plasma to accelerate removal of the metal-containing resist.
In some embodiments, thermal photoresist rework may be integrated in the same platform or even the same process chamber as other photolithography operations. That way, thermal photoresist rework may be performed without introducing a vacuum break in between operations. By way of an example, the process chamber may be a rework chamber for performing photoresist rework, and the rework chamber may also be configured to perform dry development of photoresist and/or dry etch or underlying materials.
Photoresist rework of the metal-containing resist may be combined with other dry processing operations such as dry deposition (e.g., CVD) of the metal-containing resist, dry chamber clean, or dry etch of the underlayer, or dry development. In some implementations, processing of the semiconductor substrate may combine all dry steps including film formation by vapor deposition, EUV lithographic patterning, dry development, and dry photoresist rework. Bake operations, bevel edge and/or backside clean operations, and chamber clean operations may also be dry operations. Such processing operations may avoid material and productivity costs associated with wet processing operations such as wet development. Furthermore, dry processing can provide more tunability and add further critical dimension (CD) control and possible scum removal. Employing all-dry processing operations may facilitate integration within an interconnected vacuum processing chamber without exposure to and contamination by ambient air or trace contaminants contained therein.
In some implementations, the process chamber may include a showerhead for delivery of the etch gas. In some implementations, the process chamber may include gas inlets other than the showerhead for delivery of the etch gas. The gas inlets may be positioned in regions of the process chamber where etch gas is less likely to reach through delivery via a showerhead. In some implementations, the gas inlets may be positioned below the substrate support, positioned in the walls of the process chamber, and/or positioned close to an exhaust of the process chamber. Multiple gas inlets may be used for delivery of the etch gas into the process chamber. This can ensure complete removal of the metal-containing resist from the semiconductor substrate and even throughout the process chamber.
In some implementations, the process chamber may be a thermal process chamber with one or more chamber parts for temperature control. In some embodiments, the thermal process chamber may include a heating assembly positioned underneath the semiconductor substrate. In some embodiments, the heating assembly may include a plurality of independently controllable heating zones. In some embodiments, the heating assembly may include a plurality of heating elements such as light-emitting diodes (LEDs). The LEDs may form part of an LED substrate support or chuck. In some embodiments, the heating assembly may include a radiant heating assembly that may include one or more infrared (IR) lamps.
In some implementations, the thermal process chamber may include a heating assembly positioned above the semiconductor substrate. The heating assembly may face the semiconductor substrate for substrate temperature control. As a result, heat may be directed to a frontside of the semiconductor substrate rather than through a backside. This allows the metal-containing resist to be heated without requiring heat to be transferred from the backside of the semiconductor substrate. In some embodiments, the heating assembly may include a plurality of heating elements such as LEDs. The heating elements may emit radiation from outside the process chamber through a window or port to heat the semiconductor substrate. The heating elements may alternatively emit radiation from inside the process chamber, where the heating elements may be positioned around a showerhead or positioned on the showerhead. In some embodiments, the heating assembly may include a radiant heating assembly that may include one or more IR lamps.
The heating assembly may be employed for heating the semiconductor substrate to the first elevated temperature during removal of the metal-containing resist. The heating assembly may be employed for heating the semiconductor substrate for other operations. For instance, the heating assembly may be employed to heat the semiconductor substrate for dehalogenation (e.g., removal of residual halides) on the semiconductor substrate (e.g., underlayer) or elsewhere in the process chamber (e.g., chamber walls). Additionally or alternatively, the heating assembly may be employed for treating the underlayer and/or promoting volatilization of etch byproducts.
Generally, lower temperatures may increase contrast in etch selectivity while higher temperatures may decrease contrast in etch selectivity. Thus, higher temperatures may increase volatilization of etch byproducts and limit residue formation on the semiconductor substrate. Furthermore, higher temperatures may reduce etch selectivity between the metal-containing resist and the underlayer.
Substrate temperature may be tuned to promote removal of the metal-containing resist with the etch gas. Substrate temperature may influence etch selectivity between the metal-containing resist and the underlayer. The semiconductor substrate may be heated to the first elevated temperature, where the first elevated temperature may be between about 40° C. and about 300° C., between about 60° C. and about 250° C., or between about 80° C. and about 150° C. Preferably, the first elevated temperature may be about 100° C.
Chamber pressure may be tuned, where chamber pressure may influence etch selectivity between the metal-containing resist and the underlayer. Generally, higher pressures reduce etch selectivity including etch selectivity between the metal-containing resist and the underlayer. In some implementations, chamber pressure may be between about 50 mTorr and about 765 Torr (over ambient pressure), between about 100 mTorr and about 760 Torr (ambient pressure), between about 100 mTorr and about 2000 mTorr, or between about 200 mTorr and about 1000 mTorr. Preferably, the chamber pressure may be about 400 mTorr.
Gas flow rate of the etch gas may be tuned, where gas flow may influence etch selectivity between the metal-containing resist and the underlayer during photoresist rework. In some implementations, gas flow may be between about 50 sccm and about 20000 sccm, between about 100 sccm and about 10000 sccm, between about 100 sccm and about 5000 sccm, or between about 200 sccm and about 5000 sccm. Preferably, the gas flow rate of the etch gas (e.g., hydrogen halide) may be about 470 sccm.
Duration of exposure to the etch gas may be tuned in the photoresist rework process, where exposure times may influence etch selectivity between the metal-containing resist and the underlayer. Generally speaking, longer exposure times reduce etch selectivity including etch selectivity between the metal-containing resist and the underlayer. The duration of exposure may depend on the amount of metal-containing resist to be removed, etch gas chemistry, amount of crosslinking in the resist, and composition and properties of the resist, among other factors. In some implementations, duration of exposure may be between about 1 minute and about 30 minutes, between about 2 minutes and about 20 minutes, or between about 3 minutes and about 15 minutes.
As described above, etch selectivity photoresist rework is tunable by controlling process conditions such as temperature, pressure, gas flow, duration, and gas composition, among other tunable process conditions. Tuning etch selectivity in a single step or multiple steps may achieve desired outcomes. More specifically, descumming, smoothing, dehalogenation, treatment, or removal of the underlayer may depend in part on the process conditions during photoresist rework.
Photoresist rework using thermal processes of the present disclosure may effectively remove the metal-containing resist so that there would be little to no trace of defects and residues (e.g., residual halides) remaining on the semiconductor substrate. In some implementations, photoresist rework using thermal processes of the present disclosure may substantially remove the metal-containing resist so that metal atoms (e.g., tin atoms) are present in an amount fewer than about 1×1010 atoms/cm2 on the surface of the semiconductor substrate.
The photoresist rework at block 204 may be accompanied by one or more subsequent operations. Such operations may remove any remaining metal-containing resist on the semiconductor substrate in some implementations. For instance, defectivity may be improved by an additional wet clean step after exposure to the etch gas. Alternatively, the one or more subsequent operations may treat the underlayer or remove the underlayer. The aforementioned operations may utilize plasma or thermal exposure.
At block 206 of the process 200, the underlayer is optionally exposed to removal gas at a second elevated temperature to treat or remove the underlayer. The underlayer may be treated or removed after removal of the metal-containing resist or simultaneous with removal of the metal-containing resist. Treatment of the underlayer may remove residue (e.g., residual halides or clusters of metal oxide) or other contaminants on the surface of the semiconductor substrate. In some implementations, the second elevated temperature may be greater than the first elevated temperature. In some implementations, the second elevated temperature may be between about 120° C. and about 600° C., between about 160° C. and about 500° C., or between about 200° C. and about 400° C. The increased temperature reduces etch selectivity between the metal-containing resist and the underlayer. In some implementations, the removal gas may be different than the etch gas. For example, the removal gas can include an oxidizing chemistry such as oxygen (O2), ozone (O3), or carbon dioxide (CO2). In another example, the removal gas can include a reducing chemistry such as hydrogen (H2) or forming gas (mixture of H2 and N2).
At block 208 of the process 200, the underlayer is optionally exposed to plasma to treat or remove the underlayer. The underlayer may be treated or removed after removal of the metal-containing resist or simultaneous with removal of the metal-containing resist. The plasma may be useful for desorption, descumming, dehalogenation, and smoothing operations. Plasma treatment of the underlayer may remove residue (e.g., residual halides or clusters of metal oxide) or other contaminants from the surface of the semiconductor substrate. Plasma treatment may reactivate the surface of the semiconductor substrate for subsequent metal-containing resist deposition, which may be referred to as “surface refresh.” In some instances, there may be residue or scum after photoresist rework. Residue or scum may result from slower etching components in less homogeneous EUV resist formulations, including those applied by spin-coating techniques. Such scum may include particles or clusters with high metal concentrations, which may be problematic during subsequent semiconductor processing operations. Accordingly, photoresist rework may be accompanied by treatment such as plasma treatment. During plasma treatment, the plasma power may be relatively low with high ion energy. In some implementations, the plasma power may be between about 50 W and about 1000 W, or between about 100 W and about 300 W. In some implementations, a wafer bias is between about 10 V and about 500 V, or between about 50 V and about 300 V. The duration of exposure to plasma may be relatively short so as to avoid excess plasma. In some implementations, the duration of plasma exposure is between about 0.5 seconds and about 20 seconds, or between about 1 second and about 5 seconds. In some implementations, the plasma may include ions and/or radicals of an oxidizing agent such as oxygen, ozone, or carbon dioxide. In some implementations, the plasma may include ions and/or radicals of a reducing agent such as hydrogen. In some implementations, the plasma may be generated in a plasma-generating chamber such as an inductively-coupled plasma (ICP) reactor, transformer-coupled plasma (TCP) reactor, capacitively-coupled plasma (CCP) reactor, or other reactors known in the art.
In some implementations, the process 200 further includes performing a wet clean on the semiconductor substrate to remove residual metal-containing resist from the semiconductor substrate. The wet clean may be performed after photoresist rework at block 204, after exposure to removal gas at a second elevated temperature at block 206, or after exposure to plasma at block 208. The wet clean may employ one or more inorganic acidic solutions. In some implementations, the semiconductor substrate may be exposed to an aqueous solution of a dilute acid such as dilute hydrofluoric acid (dHF) followed by exposure to another aqueous solution of a dilute acid such as dilute hydrochloric acid (dHCl). Such dilute acids may have a molar ratio (mixing ratio) of about 10:1 or more, 20:1 or more, or 100:1 or more. In some implementations, the semiconductor substrate may be exposed to an aqueous solution of a dilute acid such as dHF followed by exposure to a cleaning solution comprising ammonium hydroxide (NH4OH) and hydrogen peroxide (H2O2). In addition or in the alternative, the semiconductor substrate may be exposed to sulfuric acid (H2SO4) and its mixtures with water, H2O2, and HF, which may also be referred to as DSP (dilute sulfuric peroxide) or DSP+ (dilute sulfuric peroxide-HF). In some implementations, the wet clean may employ one or more organic acids such as acetic acid. In some implementations, the wet clean may employ semi-aqueous solvents.
In some implementations, the process 200 further includes purging and/or pumping the process chamber to remove unwanted particles. A purge gas may be flowed into the process chamber to facilitate removal of unwanted particles such as metal organic precursor and residual halides in the process chamber as well as on the semiconductor substrate. A purge of metal organic precursor and residual halides may be useful to avoid undesired byproducts. The purging and/or pumping may perform dehalogenation of the process chamber and the semiconductor substrate.
Rather than performing photoresist rework in a thermal dry environment, photoresist rework of metal-containing resist can be accomplished using wet chemistries. As such, the wet chemistries may effectively remove metal-containing resist without assistance from dry chemistries such as halogen-containing gases.
At block 302 of the process 300, a metal-containing resist is provided on an underlayer of a semiconductor substrate in a process chamber. The metal-containing resist may be deposited on the surface of the semiconductor substrate. The metal-containing resist is dry or wet deposited on the semiconductor substrate. In some implementations, the metal-containing resist is provided as a photopatterned metal-containing resist after undergoing development. In some implementations, the metal-containing resist is provided as a positive tone or negative tone resist having EUV-exposed and EUV-unexposed regions after EUV exposure. In some implementations, the metal-containing resist is provided as photopatternable metal-containing resist prior to EUV exposure and development. In some implementations, the metal-containing resist is metal-containing EUV resist, where the metal-containing EUV resist may be an organo-metal oxide or organo-metal-containing film.
The metal-containing resist is deposited on an underlayer of the substrate. The underlayer may include a device layer to be patterned using the metal-containing resist as a mask. After development of the metal-containing resist, the underlayer may be etched according to a pattern of the metal-containing resist. In some implementations, the underlayer includes spin-on glass, spin-on carbon, amorphous or crystalline carbon, or silicon oxynitride. For example, the underlayer may include carbon such as carbon deposited by PECVD. The metal-containing resist is composed of a different material than the underlayer so that a subsequent photoresist rework may be selective to the metal-containing resist relative to the underlayer.
At block 304 of the process 300, the metal-containing resist is exposed to at least an inorganic acidic solution to remove the metal-containing resist. In particular, photoresist rework may be performed with a wet clean within a wet clean chamber as the process chamber. Thus, photoresist rework may proceed using wet chemistry without assistance from plasma or dry chemistries. The inorganic acidic solution may include a strong acid having a pKa that is equal to or less than about 3.8. In some embodiments, the metal-containing resist is selectively removed relative to the underlayer. In some other embodiments, the metal-containing resist and the underlayer are removed together with exposure to the wet chemistries. The inorganic acidic solution may be applied on one or both sides of the semiconductor substrate. For instance, exposing the metal-containing resist to the inorganic acidic solution may include exposing a frontside and a backside of the semiconductor substrate to the inorganic acidic solution.
Ordinarily, photoresists are removed using organic solvents rather than inorganic acidic solutions. Inorganic acidic solutions are not typically employed in removal of photoresists. However, the inorganic acidic solutions may be applied to metal-containing resists such as organo-metal oxide photoresists for photoresist rework. Inorganic acidic solutions may include dilute acids such as dHF and dHCl. Such dilute acids may have a molar ratio (mixing ratio) of about 2:1 or more, 5:1 or more, 10:1 or more, or 20:1 or more. Other inorganic acidic solutions may include DSP or DSP+. However, it will be understood that in some other implementations, photoresist rework by wet clean may utilize organic acidic solutions such as acetic acid or semi-aqueous solvents.
Photoresist rework using wet chemistries may proceed in a multi-step sequential manner. In some implementations, an inorganic acidic solution may be initially applied to the semiconductor substrate and followed by another inorganic acidic solution or cleaning solution. In one example, photoresist rework by wet clean may occur by exposing the semiconductor substrate to dHF followed by exposing the semiconductor substrate to dHCl. Exposure to an acidic solution such as dHF may primarily serve to remove the metal-containing resist material of the photoresist. In another example, photoresist rework by wet clean may occur by exposing the semiconductor substrate to dHF followed by exposing the semiconductor substrate to a cleaning solution comprising NH4OH and H2O2. Application of such a cleaning solution may constitute an RCA-1 clean developed by the RCA Corporation, which is also referred to as standard clean-1 (“SC-1”).
Photoresist rework of the metal-containing resist may be combined with other wet processing operations such as wet deposition (e.g., spin-on techniques), wet etch of the underlayer, or wet development. In some implementations, processing of the semiconductor substrate may combine multiple wet steps including film formation by wet deposition, wet development, and wet photoresist rework.
In some implementations, the process chamber may be a wet clean chamber with one or more parts for fluid delivery. In some implementations, the process chamber may be a spin-rinse-drying (SRD) station in a semiconductor processing tool. The wet clean chamber may be equipped with one or more nozzles for discharging fluids such as the inorganic acidic solution. In some embodiments, the one or more nozzles may be movable for positioning over certain locations of the semiconductor substrate. In some embodiments, the wet clean chamber may be equipped with a rotatable substrate support or chuck so that cleaning/acidic solutions may be driven outwardly from the edge of a rotating substrate. In some embodiments, the wet clean chamber may be equipped with one or more heating elements for temperature control during wet photoresist rework. Such heating elements may include a one or more LEDs or IR lamps. In some embodiments, the one or more heating elements may be positioned under the semiconductor substrate and facing a backside of the semiconductor substrate. Heating the semiconductor substrate may promote removal of the metal-containing resist. Additionally or alternatively, heating the semiconductor substrate may promote evaporation of a liquid from the semiconductor substrate. Heating the semiconductor substrate may also promote dehalogenation, desorption, descumming, or smoothing operations. Other conditions that may be tuned to influence wet clean of the metal-containing resist may include spin speed of the rotatable substrate support, where faster spin speeds may promote removal of the metal-containing resist, and boom swing (i.e., dispenser arm location movement over the semiconductor substrate).
Photoresist rework using wet chemistries may not only remove metal-containing resist, but may also treat or remove the underlayer. In some embodiments, application of at least the inorganic acidic solution selectively removes the metal-containing resist relative to the underlayer. In other words, the inorganic acidic solution may remove the metal-containing resist while substantially preserving the underlayer. In some embodiments, the wet clean may treat the surface of the underlayer. The wet clean treatment of the underlayer may involve a dilute inorganic acidic solution or cleaning solution such as SC-1. The wet clean treatment may remove residues and various contaminants so that the surface may be reactivated for subsequent deposition of photoresist. That way, lithographic processes may be repeated on the underlayer with negligible or no significant impact after the photoresist rework using wet chemistries.
Photoresist rework using wet chemistries of the present disclosure may effectively remove the metal-containing resist so that there would be little to no trace of defects and residues remaining on the semiconductor substrate. In some implementations, photoresist rework using wet chemistries of the present disclosure may substantially remove the metal-containing resist so that metal atoms (e.g., tin atoms) are present at an amount fewer than about 1×1010 atoms/cm2 on the surface of the semiconductor substrate.
In some implementations, the process 300 may further include exposure to a thermal processor plasma process as described in the present disclosure. The thermal processor plasma process may be employed to remove the underlayer or treat the underlayer for improved defectivity.
In
In
While this disclosure frequently refers to the removal of EUV-sensitive films that have been exposed and/or developed, the removal processes described can be extended to films of similar composition (e.g., other MOxRy-based films), for example, other films containing a metal oxide or organometallic film. In some implementations, films other than EUV resists can be removed by this method, for example hard masks, UV resists or films of similar composition having other applications; in this respect, the described removal process relates to the film's chemical composition, as opposed to its function.
An apparatus of the present disclosure is configured for photoresist rework of metal-containing photoresist. The apparatus may be configured for other processing operations such as deposition, bevel and backside cleaning, post-application baking, EUV scanning, post-exposure baking, development, descum, smoothing, curing, and other operations. In some implementations, the apparatus is configured to perform multiple dry operations. In some implementations, the apparatus is configured to perform a combination of wet and dry operations. The apparatus may include a single wafer chamber or multiple stations in the same process chamber. With multiple stations in the same process chamber, various processing operations such as those described in the present disclosure may be performed in different stations in the same process chamber.
The apparatus configured for photoresist rework of metal-containing photoresist includes a process chamber with a substrate support. The apparatus may include an etch gas line coupled to the process chamber for delivery of etch gas. In some implementations, the etch gas includes a halide such as a hydrogen halide. The apparatus may include one or more heaters for temperature control. Such heaters may be provided in the process chamber and/or in the substrate support. Or, such heaters may be provided outside the process chamber. The apparatus may further include one or more sensors for sensing particle count, wafer count, thickness count, or other parameters for triggering an endpoint of the photoresist rework.
In some implementations, the process chamber is made of an inexpensive material such as plastic. In some other implementations, the process chamber is made of a metal such as anodized aluminum or a ceramic such as aluminum oxide.
A process station may be configured as a module in a cluster tool.
Returning to
Showerhead 706 distributes process gases toward substrate 712. In the implementation shown in
In some implementations, pedestal 708 may be raised or lowered to expose substrate 712 to a volume between the substrate 712 and the showerhead 706. It will be appreciated that, in some implementations, pedestal height may be adjusted programmatically by a suitable computer controller 750. In some implementations, the showerhead 706 may have multiple plenum volumes with multiple temperature controls.
In some implementations, pedestal 708 may be temperature controlled via heater 710. In some implementations, the pedestal 708 may be heated to a temperature of greater than 0° C. and up to 300° C., for example 60° C. to 250° C., such as about 80° C. to 200° C., during non-plasma thermal exposure of a metal-containing resist to halide or organic vapor chemistry, as described in disclosed implementations. In some implementations, the heater 710 of the pedestal 708 may include a plurality of independently controllable temperature control zones.
Further, in some implementations, pressure control for process station 700 may be provided by a butterfly valve 718. As shown in the implementation of
In some implementations, a position of showerhead 706 may be adjusted relative to pedestal 708 to vary a volume between the substrate 712 and the showerhead 706. Further, it will be appreciated that a vertical position of pedestal 708 and/or showerhead 706 may be varied by any suitable mechanism within the scope of the present disclosure. In some implementations, pedestal 708 may include a rotational axis for rotating an orientation of substrate 712. It will be appreciated that, in some implementations, one or more of these example adjustments may be performed programmatically by one or more suitable computer controllers 750.
Where plasma may be used, for example in descumming, treatment, or smoothing operations, showerhead 706 and pedestal 708 electrically communicate with a radio frequency (RF) power supply 714 and matching network 716 for powering a plasma. In some implementations, the plasma energy may be controlled by controlling one or more of a process station pressure, a gas concentration, an RF source power, an RF source frequency, and a plasma power pulse timing. For example, RF power supply 714 and matching network 716 may be operated at any suitable power to form a plasma having a desired composition of radical species. Examples of suitable powers are up to about 500 W.
In some implementations, instructions for a controller 750 may be provided via input/output control (IOC) sequencing instructions. In one example, the instructions for setting conditions for a process phase may be included in a corresponding recipe phase of a process recipe. In some cases, process recipe phases may be sequentially arranged, so that all instructions for a process phase are executed concurrently with that process phase. In some implementations, instructions for setting one or more reactor parameters may be included in a recipe phase. For example, a recipe phase may include instructions for setting a flow rate of an etch gas, such as a hydrogen halide, and time delay instructions for the recipe phase. In some implementations, the controller 750 may include any of the features described below with respect to system controller 850 of
As described above, one or more process stations may be included in a multi-station processing tool.
Where the inbound load lock 802 includes a remote plasma source, the wafer may be exposed to a remote plasma treatment to treat the substrate surface in the load lock prior to being introduced into a processing chamber 814. Further, the wafer also may be heated in the inbound load lock 802 as well, for example, to remove moisture and adsorbed gases. Next, a chamber transport port 816 to processing chamber 814 is opened, and another robot (not shown) places the wafer into the reactor on a pedestal of a first station shown in the reactor for processing. While the implementation depicted in
The depicted processing chamber 814 includes four process stations, numbered from 1 to 4 in the implementation shown in
In some implementations, system controller 850 controls all of the activities of process tool 800. System controller 850 executes system control software 858 stored in mass storage device 854, loaded into memory device 856, and executed on processor 852. Alternatively, the control logic may be hard coded in the controller 850. Applications Specific Integrated Circuits, Programmable Logic Devices (e.g., field-programmable gate arrays, or FPGAs) and the like may be used for these purposes. In the following discussion, wherever “software” or “code” is used, functionally comparable hard coded logic may be used in its place. System control software 858 may include instructions for controlling the timing, mixture of gases, gas flow rates, chamber and/or station pressure, chamber and/or station temperature, wafer temperature, target power levels, RF power levels, substrate pedestal, chuck and/or susceptor position, and other parameters of a particular process performed by process tool 800. System control software 858 may be configured in any suitable way. For example, various process tool component subroutines or control objects may be written to control operation of the process tool components used to carry out various process tool processes. System control software 858 may be coded in any suitable computer readable programming language.
In some implementations, system control software 858 may include input/output control (IOC) sequencing instructions for controlling the various parameters described above. Other computer software and/or programs stored on mass storage device 854 and/or memory device 856 associated with system controller 850 may be employed in some implementations. Examples of programs or sections of programs for this purpose include a substrate positioning program, a process gas control program, a pressure control program, a heater control program, and a plasma control program.
A substrate positioning program may include program code for process tool components that are used to load the substrate onto pedestal 818 and to control the spacing between the substrate and other parts of process tool 800.
A process gas control program may include code for controlling organic vapor composition (e.g., trifluoroacetic acid as described herein) and flow rates and optionally for flowing gas into one or more process stations prior to deposition in order to stabilize the pressure in the process station. A pressure control program may include code for controlling the pressure in the process station by regulating, for example, a throttle valve in the exhaust system of the process station, a gas flow into the process station, etc.
A heater control program may include code for controlling the current to a heating unit that is used to heat the substrate. Alternatively, the heater control program may control delivery of a heat transfer gas (such as helium) to the substrate.
A plasma control program may include code for setting RF power levels applied to the process electrodes in one or more process stations in accordance with the implementations herein.
A pressure control program may include code for maintaining the pressure in the reaction chamber in accordance with the implementations herein.
In some implementations, there may be a user interface associated with system controller 850. The user interface may include a display screen, graphical software displays of the apparatus and/or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.
In some implementations, parameters adjusted by system controller 850 may relate to process conditions. Non-limiting examples include process gas composition and flow rates, temperature, pressure, plasma conditions (such as RF bias power levels), etc. These parameters may be provided to the user in the form of a recipe, which may be entered utilizing the user interface.
Signals for monitoring the process may be provided by analog and/or digital input connections of system controller 850 from various process tool sensors. The signals for controlling the process may be output on the analog and digital output connections of process tool 800. Non-limiting examples of process tool sensors that may be monitored include mass flow controllers, pressure sensors (such as manometers), thermocouples, etc. Appropriately programmed feedback and control algorithms may be used with data from these sensors to maintain process conditions.
System controller 850 may provide program instructions for implementing the above-described deposition processes. The program instructions may control a variety of process parameters, such as DC power level, RF bias power level, pressure, temperature, etc. The instructions may control the parameters to operate development, clean, and/or etch processes according to various implementations described herein.
The system controller 850 will typically include one or more memory devices and one or more processors configured to execute the instructions so that the apparatus will perform a method in accordance with disclosed implementations. Machine-readable media containing instructions for controlling process operations in accordance with disclosed implementations may be coupled to the system controller 850.
In some implementations, the system controller 850 is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The system controller 850, depending on the processing conditions and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.
Broadly speaking, the system controller 850 may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the system controller 850 in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some implementations, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.
The system controller 850, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the system controller 850 may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the system controller 850 receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the system controller 850 is configured to interface with or control. Thus as described above, the system controller 850 may be distributed, such as by including one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.
Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an ALD chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, an EUV lithography chamber (scanner) or module, a development chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.
As noted above, depending on the process step or steps to be performed by the tool, the system controller 850 might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.
ICP reactors which, in certain implementations, may be suitable for etch operations suitable for implementation of some implementations, are now described. Although ICP reactors are described herein, in some implementations, it should be understood that capacitively coupled plasma reactors may also be used.
The inductively coupled plasma apparatus 900 includes an overall process chamber 924 structurally defined by chamber walls 901 and a window 911. The chamber walls 901 may be fabricated from stainless steel, aluminum, or plastic. The window 911 may be fabricated from quartz or other dielectric material. An optional internal plasma grid 950 divides the overall process chamber into an upper sub-chamber 902 and a lower sub chamber 903. In most implementations, plasma grid 950 may be removed, thereby utilizing a chamber space made of sub chambers 902 and 903. A chuck 917 is positioned within the lower sub-chamber 903 near the bottom inner surface. The chuck 917 is configured to receive and hold a semiconductor wafer 919 upon which the etching and deposition processes are performed. The chuck 917 can be an electrostatic chuck for supporting the wafer 919 when present. In some implementations, an edge ring (not shown) surrounds chuck 917, and has an upper surface that is approximately planar with atop surface of the wafer 919, when present over chuck 917. The chuck 917 also includes electrostatic electrodes for chucking and dechucking the wafer 919. A filter and DC clamp power supply (not shown) may be provided for this purpose. Other control systems for lifting the wafer 919 off the chuck 917 can also be provided. The chuck 917 can be electrically charged using an RF power supply 923. The RF power supply 923 is connected to matching circuitry 921 through a connection 927. The matching circuitry 921 is connected to the chuck 917 through a connection 925. In this manner, the RF power supply 923 is connected to the chuck 917. In various implementations, a bias power of the electrostatic chuck may be set at about 50 V or may be set at a different bias power depending on the process performed in accordance with disclosed implementations. For example, the bias power may be between about 20 Vb and about 100 V, or between about 30 V and about 150 V.
Elements for plasma generation include a coil 933 is positioned above window 911. In some implementations, a coil is not used in disclosed implementations. The coil 933 is fabricated from an electrically conductive material and includes at least one complete turn. The example of a coil 933 shown in
Process gases may be flowed into the process chamber through one or more main gas flow inlets 960 positioned in the upper sub-chamber 902 and/or through one or more side gas flow inlets 970. Likewise, though not explicitly shown, similar gas flow inlets may be used to supply process gases to a capacitively coupled plasma processing chamber. A vacuum pump, e.g., a one or two stage mechanical dry pump and/or turbomolecular pump 940, may be used to draw process gases out of the process chamber 924 and to maintain a pressure within the process chamber 924. For example, the vacuum pump may be used to evacuate the lower sub-chamber 903 during a purge operation. A valve-controlled conduit may be used to fluidically connect the vacuum pump to the process chamber 924 so as to selectively control application of the vacuum environment provided by the vacuum pump. This may be done employing a closed loop-controlled flow restriction device, such as a throttle valve (not shown) or a pendulum valve (not shown), during operational plasma processing. Likewise, a vacuum pump and valve controlled fluidic connection to the capacitively coupled plasma processing chamber may also be employed.
During operation of the apparatus 900, one or more process gases may be supplied through the gas flow inlets 960 and/or 970. In certain implementations, process gas may be supplied only through the main gas flow inlet 960, or only through the side gas flow inlet 970. In some cases, the gas flow inlets shown in the figure may be replaced by more complex gas flow inlets, one or more showerheads, for example. The Faraday shield 949a and/or optional grid 950 may include internal channels and holes that allow delivery of process gases to the process chamber 924. Either or both of Faraday shield 949a and optional grid 950 may serve as a showerhead for delivery of process gases. In some implementations, a liquid vaporization and delivery system may be situated upstream of the process chamber 924, such that once a liquid reactant or precursor is vaporized, the vaporized reactant or precursor is introduced into the process chamber 924 via a gas flow inlet 960 and/or 970.
Radio frequency power is supplied from the RF power supply 941 to the coil 933 to cause an RF current to flow through the coil 933. The RF current flowing through the coil 533 generates an electromagnetic field about the coil 933. The electromagnetic field generates an inductive current within the upper sub-chamber 902. The physical and chemical interactions of various generated ions and radicals with the wafer 919 etch features of and selectively deposit layers on the wafer 919.
If the plasma grid 950 is used such that there is both an upper sub-chamber 902 and a lower sub-chamber 903, the inductive current acts on the gas present in the upper sub-chamber 902 to generate an electron-ion plasma in the upper sub-chamber 902. The optional internal plasma grid 950 limits the amount of hot electrons in the lower sub-chamber 903. In some implementations, the apparatus 900 is designed and operated such that the plasma present in the lower sub-chamber 903 is an ion-ion plasma.
Both the upper electron-ion plasma and the lower ion-ion plasma may contain positive and negative ions, though the ion-ion plasma will have a greater ratio of negative ions to positive ions. Volatile etching and/or deposition byproducts may be removed from the lower sub-chamber 903 through port 922. The chuck 917 disclosed herein may operate at elevated temperatures ranging between about 10° C. and about 250° C. The temperature will depend on the process operation and specific recipe.
Apparatus 900 may be coupled to facilities (not shown) when installed in a clean room or a fabrication facility. Facilities include plumbing that provide processing gases, vacuum, temperature control, and environmental particle control. These facilities are coupled to apparatus 900, when installed in the target fabrication facility. Additionally, apparatus 900 may be coupled to a transfer chamber that allows robotics to transfer semiconductor wafers into and out of apparatus 900 using typical automation.
In some implementations, a system controller 930 (which may include one or more physical or logical controllers) controls some or all of the operations of a process chamber 924. The system controller 930 may include one or more memory devices and one or more processors. In some implementations, the apparatus 900 includes a switching system for controlling flow rates and durations when disclosed implementations are performed. In some implementations, the apparatus 900 may have a switching time of up to about 500 ms, or up to about 750 ms. Switching time may depend on the flow chemistry, recipe chosen, reactor architecture, and other factors.
In some implementations, the system controller 930 is part of a system, which may be part of the above-described examples. Such systems can include semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be integrated into the system controller 930, which may control various components or subparts of the system or systems. The system controller 930, depending on the processing parameters and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.
Broadly speaking, the system controller 930 may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some implementations, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication or removal of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.
The system controller 930, in some implementations, may be a part of or coupled to a computer that is integrated with, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the system controller 930 receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the system controller 930 may be distributed, such as by including one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.
Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an ALD chamber or module, an ALE chamber or module, an ion implantation chamber or module, a track chamber or module, an EUV lithography chamber (scanner) or module, a dry development chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.
As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.
EUVL patterning may be conducted using any suitable tool, often referred to as a scanner, for example the TWINSCAN NXE: 3300B® platform supplied by ASML of Veldhoven, NL). The EUVL patterning tool may be a standalone device from which the substrate is moved into and out of for deposition and etching as described herein. Or, as described below, the EUVL patterning tool may be a module on a larger multi-component tool.
A vacuum transport module (VTM) 1038 interfaces with four processing modules 1020a-1020d, which may be individually optimized to perform various fabrication processes. By way of example, processing modules 1020a-1020d may be implemented to perform deposition, evaporation, ELD, dry development, clean, etch, strip, and/or other semiconductor processes. For example, module 1020a may be an ALD reactor that may be operated to perform in a non-plasma, thermal atomic layer depositions as described herein, such as Vector tool, available from Lam Research Corporation, Fremont, CA. And module 1020b may be a PECVD tool, such as the Lam Vector®. It should be understood that the figure is not necessarily drawn to scale.
Airlocks 1042 and 1046, also known as a loadlocks or transfer modules, interface with the VTM 1038 and a patterning module 1040. For example, as noted above, a suitable patterning module may be the TWINSCAN NXE: 3300B® platform supplied by ASML of Veldhoven, NL). This tool architecture allows for work pieces, such as semiconductor substrates or wafers, to be transferred under vacuum so as not to react before exposure. Integration of the deposition modules with the lithography tool is facilitated by the fact that EUVL also requires a greatly reduced pressure given the strong optical absorption of the incident photons by ambient gases such as H2O, O2, etc.
As noted above, this integrated architecture is just one possible implementation of a tool for implementation of the described processes. The processes may also be implemented with a more conventional stand-alone EUVL scanner and a deposition reactor, such as a Lam Vector tool, either stand alone or integrated in a cluster architecture with other tools, such as etch, strip etc. (e.g., Lam Kiyo or Gamma tools), as modules, for example as described with reference to
Airlock 1042 may be an “outgoing” loadlock, referring to the transfer of a substrate out from the VTM 1038 serving a deposition module 1020a to the patterning module 1040, and airlock 1046 may be an “ingoing” loadlock, referring to the transfer of a substrate from the patterning module 1040 back in to the VTM 1038. The ingoing loadlock 1046 may also provide an interface to the exterior of the tool for access and egress of substrates. Each process module has a facet that interfaces the module to VTM 1038. For example, deposition process module 1020a has facet 1036. Inside each facet, sensors, for example, sensors 1-18 as shown, are used to detect the passing of wafer 1026 when moved between respective stations. Patterning module 1040 and airlocks 1042 and 1046 may be similarly equipped with additional facets and sensors, not shown.
Main VTM robot 1022 transfers wafer 1026 between modules, including airlocks 1042 and 1046. In one implementation, robot 1022 has one arm, and in another implementation, robot 1022 has two arms, where each arm has an end effector 1024 to pick wafers such as wafer 1026 for transport. Front-end robot 1044, in is used to transfer wafers 1026 from outgoing airlock 1042 into the patterning module 1040, from the patterning module 1040 into ingoing airlock 1046. Front-end robot 1044 may also transport wafers 1026 between the ingoing loadlock and the exterior of the tool for access and egress of substrates. Because ingoing airlock module 1046 has the ability to match the environment between atmospheric and vacuum, the wafer 1026 is able to move between the two pressure environments without being damaged.
It should be noted that an EUVL tool typically operates at a higher vacuum than a deposition tool. If this is the case, it is desirable to increase the vacuum environment of the substrate during the transfer between the deposition to the EUVL tool to allow the substrate to degas prior to entry into the patterning tool. Outgoing airlock 1042 may provide this function by holding the transferred wafers at a lower pressure, no higher than the pressure in the patterning module 1040, for a period of time and exhausting any off-gassing, so that the optics of the patterning module 1040 are not contaminated by off-gassing from the substrate. A suitable pressure for the outgoing, off-gassing airlock is no more than 1E−8 Torr.
In some implementations, a system controller 1050 (which may include one or more physical or logical controllers) controls some or all of the operations of the cluster tool and/or its separate modules. It should be noted that the controller can be local to the cluster architecture, or can be located external to the cluster architecture in the manufacturing floor, or in a remote location and connected to the cluster architecture via a network. The system controller 1050 may include one or more memory devices and one or more processors. The processor may include a central processing unit (CPU) or computer, analog and/or digital input/output connections, stepper motor controller boards, and other like components. Instructions for implementing appropriate control operations are executed on the processor. These instructions may be stored on the memory devices associated with the controller or they may be provided over a network. In certain implementations, the system controller executes system control software.
The system control software may include instructions for controlling the timing of application and/or magnitude of any aspect of tool or module operation. System control software may be configured in any suitable way. For example, various process tool component subroutines or control objects may be written to control operations of the process tool components necessary to carry out various process tool processes. System control software may be coded in any suitable compute readable programming language. In some implementations, system control software includes input/output control (IOC) sequencing instructions for controlling the various parameters described above. For example, each phase of a semiconductor fabrication process may include one or more instructions for execution by the system controller. The instructions for setting process conditions for condensation, deposition, evaporation, patterning and/or etching phase may be included in a corresponding recipe phase, for example.
In various implementations, an apparatus for forming a negative pattern mask is provided. The apparatus may include a processing chamber for patterning, deposition and etch, and a controller including instructions for forming a negative pattern mask. The instructions may include code for, in the processing chamber, patterning a feature in a chemically amplified (CAR) resist on a semiconductor substrate by EUV exposure to expose a surface of the substrate, developing the photopatterned resist, and etching the underlying layer or layer stack using the patterned resist as a mask. Development may be performed using an organic vapor such as an organic acid.
It should be noted that the computer controlling the wafer movement can be local to the cluster architecture, or can be located external to the cluster architecture in the manufacturing floor, or in a remote location and connected to the cluster architecture via a network. A controller as described above with respect to any of
The wafer support 1124 may, for example, include an electrostatic chuck (ESC) 1126, which may be used to provide a wafer support surface for supporting the substrate 1122. The ESC 1126 may include, for example, a base plate 1134 that is bonded to a top plate 1128 that is placed atop the base plate 1134. The top plate 1128 may, for example, be made of a ceramic material and may have embedded within it several other components. In the depicted example, the top plate 1128 has two separate electrical systems embedded within it. One such system is an electrostatic clamping electrode system, which may have one or more clamping electrodes 1132 that may be used to generate an electric charge within the substrate 1122 that causes the substrate 1122 to be drawn against the wafer support surface of the top plate 1128. In the implementation of
The other system is a thermal control system that may be used to control the temperature of the substrate 1122 during processing conditions. In
In some implementations, of, for example, temperature control mechanisms discussed above, heat pumps may be used instead of resistance heating traces. For example, in some implementations, the resistance heater traces may be replaced by, or augmented by, Peltier junctions or other, similar devices that may be controlled to “pump” heat from one side thereof to another. Such mechanisms may be used, for example, to draw heat from the top plate 1128 (and thus the substrate 1122) and direct it into the base plate 1134 and the heat exchange passages 1136, thereby allowing the substrate 1122 to be cooled more rapidly and more effectively, if desired.
The ESC 1126 may also include, for example, a base plate 1134 that may be used to provide structural support to the underside of the top plate 1128 and which may also act as a heat dispersion system. For example, the base plate 1134 may include one or more heat exchange passages 1136 that are arranged in a generally distributed fashion throughout the base plate 1134, e.g., the heat exchange passages 1136 may follow a serpentine, circular switchback, or spiral pattern around the center of the base plate 1134. A heat exchange medium, e.g., water or inert fluorinated liquid, may be circulated through the heat exchange passages 1136 during use. The flow rate and temperature of the heat exchange medium may be externally controlled so as to result in a particular heating or cooling behavior in the base plate 1134.
The ESC 1126 may, for example, be supported by a wafer support housing 1142 that is connected with, and supported by, a wafer support column 1144. The wafer support column 1144 may, for example, have a routing passage 1148 other pass-throughs for routing cabling, fluid flow conduits, and other equipment to the underside of the base plate 1134 and/or the top plate 1128. For example, while not shown in
The apparatus 1100 of
The wafer support 1124 may also include, in some implementations, one or more edge rings that may be used to control and/or fine-tune various process conditions. In
The apparatus 1100 may also include a system for removing process gases from the process chamber 1102 during and after processing concludes. For example, the process chamber 1102 may include an annular plenum 1156 that encircles the wafer support column 1144. The annular plenum 1156 may, in turn, be fluidically connected with a vacuum foreline 1152 that may be connected with a vacuum pump, e.g., such as may be located beneath a subfloor below the apparatus 1100. A regulator valve 1154 may be provided in between the vacuum foreline 1152 and the process chamber 1102 and actuated to control the flow into the vacuum foreline 1152. In some implementations, a baffle 1150, e.g., an annular plate or other structure that may serve to make the flow into the annular plenum 1156 more evenly distributed about the circumference of the wafer support column 1144, may be provided to reduce the chances of flow non-uniformities developing in reactants flowed across the substrate 1122.
The showerhead 1110, as shown, is a dual-plenum showerhead 1110 and includes a first plenum 1112 that is provided process gas via a first inlet 1116 and a second plenum 1114 that is provided process gas via a second inlet 1118. Generally, two plenums can be employed to maintain separation between the precursor(s) and the counter-reactant(s) prior to release of the precursor and the counter-reactant. The showerhead 1110 may, in some implementations, have more than two plenums. In some instances, a single plenum is used to deliver the precursor(s) into the reaction space 1120 of the processing chamber 1102. Each plenum may have a corresponding set of gas distribution ports that fluidically connect the respective plenum with the reaction space 1120 through the faceplate of the showerhead 1110 (the faceplate being the portion of the showerhead 1110 that is interposed between the lowermost plenum and the reaction space 1120).
The first inlet 1116 and the second inlet 1118 of the showerhead 1110 may be provided processing gases via a gas supply system, which may be configured to provide one or more precursor(s) and/or counter-reactant(s), as discussed herein. The depicted apparatus 1100 is configured to provide multiple precursors and multiple counter-reactants. For example, a first valve manifold 1168a may be configured to provide precursor(s) to the first inlet 1116, while a second valve manifold 1168b may be configured to provide other precursor(s) or other counter-reactants to the second inlet 1118.
A first valve manifold 1168a may be configured to provide one or more precursor(s) to the first inlet 1116, while a second valve manifold 1168b may be configured to provide other precursor(s) or other reactant to the second inlet 1118. In this example, the first valve manifold 1168a, for example, includes multiple valves A1-A5. Valve A2 may, for example, be a three-way valve that has one port fluidically connected with a first vaporizer 1172a, another port fluidically connected with a bypass line 1170a, and a third port fluidically connected with a port on another 3-way valve A3. Similarly, valve A4 may be another three-way valve that has one port fluidically connected with a second vaporizer 1172b, another port fluidically connected with the bypass line 1170a, and a third port fluidically connected with a port on another 3-way valve A5. One of the other ports on valve A5 may be fluidically connected with the first inlet 1116 while the remaining port on valve A5 may be fluidically connected with one of the remaining ports on the valve A3. The remaining port on the valve A3 may, in turn, be fluidically connected with the valve A1 which may be fluidically interposed between the valve A3 and a purge gas source 1174, e.g., nitrogen, argon, or other suitably inert gas (with respect to precursor(s) and/or counter-reactant(s)). In some implementations, only the first valve manifold is employed.
For the purposes of this disclosure, the term “fluidically connected” is used with respect to volumes, plenums, holes, etc., that may be connected with one another in order to form a fluidic connection, similar to how the term “electrically connected” is used with respect to components that are connected together to form an electric connection. The term “fluidically interposed,” if used, may be used to refer to a component, volume, plenum, or hole that is fluidically connected with at least two other components, volumes, plenums, or holes such that fluid flowing from one of those other components, volumes, plenums, or holes to the other or another of those components, volumes, plenums, or holes would first flow through the “fluidically interposed” component before reaching that other or another of those components, volumes, plenums, or holes. For example, if a pump is fluidically interposed between a reservoir and an outlet, fluid that flowed from the reservoir to the outlet would first flow through the pump before reaching the outlet.
The first valve manifold 1168a may, for example, be controllable to cause vapors from one or both of the vaporizers 1172a and 1172b to be flowed either to the process chamber 1102 or through the first bypass line 1170a and into the vacuum foreline 1152. The first valve manifold 1168a may also be controllable to cause a purge gas to be flowed from the purge gas source 1174 and into the first inlet 1116.
For example, to flow vapor from the first vaporizer 1172a into the reaction space 1120, the valve A2 may be actuated to cause the vapor from the first vaporizer 1172a to first flow into the first bypass line 1170a. This flow may be maintained for a period of time sufficient to allow the flow of the vapor to reach steady state flow conditions. After sufficient time has passed (or after a flow meter, if used, indicates that the flow rate is stable), valves A2, A3, and A5 may be actuated to cause the vapor flow from the first vaporizer 1172a to be directed to the first inlet. Similar operations with valves A4 and A5 may be performed to deliver vapor from the second vaporizer 1172b to the first inlet 1116. In some instances, it may be desirable to purge one of the vapors from the first plenum 1112 by actuating the valves A1, A3, and A5 so as to cause the purge gas from the purge gas source 1174 to be flowed into the first inlet 1116. In some additional implementations, it may be desirable to simultaneously flow vapor from one of the vaporizers 1172a or 1172b in tandem with flowing gas from the purge gas into the first inlet 1116. Such implementations may be used to dilute the concentration of the reactant(s) contained in such vapor(s).
It will be appreciated that the second valve manifold 1168b may be controlled in a similar manner, e.g., by controlling valves B1-B5, to provide vapors from vaporizers 1172c and 1172d to the second inlet 1118 or to the second bypass line 1170b. It will be further appreciated that different manifold arrangements may be utilized as well, including a single unitary manifold that includes valves for controlling flow of the precursor(s), counter-reactant(s), or other reactants to the first inlet 1116 and the second inlet 1118.
As mentioned earlier, some apparatuses 1100 may feature a lesser number of vapor sources, e.g., only two vaporizers 1172, in which case the valve manifold(s) 1168 may be modified to have a lesser number of valves, e.g., only valves A1-A3.]
As discussed above, apparatuses such as apparatus 1100, which may be used to provide for dry deposition of films, may be configured to maintain particular temperature profiles within the process chamber 1102. In particular, such apparatuses 1100 may be configured to maintain the substrate 1122 at a lower temperature, e.g., at least 25° C. to 50° C. lower, than most of the equipment of the apparatus 1100 that comes into direct contact with the precursor(s) and/or counter-reactant(s). Additionally, the temperature of the equipment of the apparatus 1100 that comes into direct contact with the precursor(s) and/or counter-reactant(s) may be kept to an elevated level that is sufficiently high that condensation of the vaporized reactants on the surfaces of such equipment is discouraged. At the same time, the substrate 1122 temperature may be controlled to a level that promotes condensation, or at least deposition, of the reactants on the substrate 1122.
To provide for such temperature control, various heating systems may be included in the apparatus 1100. For example, the process chamber 1102 may have receptacles for receiving cartridge heaters 1158, e.g., for a process chamber 1102 that has a generally cylindrical interior volume but a square or rectangular external shape, vertical holes for receiving cartridge heaters 1158 may be bored into the four corners of the chamber 1102 housing. In some implementations, the showerhead 1110 may be covered with heater blankets 1160, which may be used to apply heat across the exposed upper surface of the showerhead 1110 to keep the showerhead temperature elevated. It may also be beneficial to heat various gas lines that are used to conduct the vaporized reactants from the vaporizers 1172 to the showerhead 1110. For example, resistive heater tape may be wound around such gas lines and used to heat them to an elevated temperature. As shown in
The various operational systems of the apparatus 1100 may be controlled by a controller 1184, which may include one or more processors 1186 and one or more memory devices 1188 that are operatively connected with each other and that are communicatively connected with various systems and subsystems of the apparatus 1100 so as to provide for control functionality for those systems. For example, the controller 1184 may be configured to control the valves A1-A5 and B1-B5, the various heaters 1158, 1160, the vaporizers 1172, the regulator valve 1154, the gate valve 1106, the wafer support z-actuator, and so forth.
The controller 1184 may be configured, e.g., via execution of computer-executable instructions, to cause the apparatus 1100 to perform various operations consistent with the disclosure provided above.
Once the metal-containing resist film has been deposited on the substrate 1122, the substrate 1122 may, as noted above, be transferred to one or more subsequent process chambers or tool for additional operations (e.g., any described herein). Further deposition apparatuses are described in International Patent Application No. PCT/US2020/038968, filed Jun. 22, 2020, titled “APPARATUS FOR PHOTORESIST DRY DEPOSITION,” which is herein incorporated by reference in its entirety.
Process and apparatus for dry development of metal and/or metal oxide photoresists, for example to form a patterning mask in the context of EUV patterning is disclosed.
It is understood that the examples and implementations described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art. Although various details have been omitted for clarity's sake, various design alternatives may be implemented. Therefore, the present examples are to be considered as illustrative and not restrictive, and the disclosure is not to be limited to the details given herein, but may be modified within the scope of the disclosure.
A PCT Request Form is filed concurrently with this specification as part of the present application. Each application that the present application claims benefit of or priority to as identified in the concurrently filed PCT Request Form is incorporated by reference herein in its entirety and for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2022/037733 | 7/20/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63203715 | Jul 2021 | US |
