Patent Application
20250216763
The present disclosure relates generally to methods for forming an anti-spacer patterned mask, and more particularly, photolithography materials and processes in methods for forming an anti-spacer patterned mask during manufacturing of semiconductor devices.
In photolithography for semiconductor manufacturing, a relief pattern can be topographical variation created on a surface of and/or through a photoresist material layer. A relief pattern can be formed when portions of a photoresist material layer are selectively exposed to light and then selectively removed, resulting in regions with different heights or levels, such as trenches and holes formed in and patterned in a layer or film of photoresist material. The photoresist material is a light-sensitive material that undergoes chemical changes when exposed to ultraviolet (UV) light, extreme ultraviolet (EUV) light (e.g., light with a wavelength of 13.5 nm) or an electron beam. The photoresist material is typically exposed to a patterned light through a mask or directly using a laser. The pattern transferred to the photoresist material by exposure to light defines exposed areas and regions of the photoresist material.
In positive photoresists, the exposed regions become soluble and can be removed in a development process by chemicals of a developer solvent. In negative photoresists, the exposed regions become insoluble, and the unexposed areas can be removed in a development process by chemicals of a developer solvent. After exposure and pattern transfer, the wafer can be subjected to a chemical developer that dissolves the soluble parts of the photoresist to create a relief pattern on the surface of and/or through the photoresist material layer, such that the exposed (or unexposed) areas are removed, leaving behind patterned features. Then, this relief pattern can be used as a mask for further processing steps, such as etching or ion implantation, to transfer the pattern (design) into underlying layers and/or a substrate of the wafer.
In material processing methodologies (such as photolithography), creating patterned layers typically involves the application of a thin layer of radiation-sensitive material, such as photoresist, to an upper surface of a substrate. This radiation-sensitive material is transformed into a patterned mask that can be used to etch or transfer a pattern into an underlying layer on a substrate. Patterning of the radiation-sensitive material generally involves exposure by a radiation source through a reticle (and associated optics) onto the radiation-sensitive material using, for example, a photolithographic exposure system.
This exposure creates a latent pattern within the radiation-sensitive material which can then be developed. Developing refers to dissolving and removing a portion of the radiation-sensitive material to yield a relief pattern (topographic pattern). The portion of material removed can be either irradiated regions or non-irradiated regions of the radiation-sensitive material depending on a photoresist tone and/or type of developing solvent used. The relief pattern can then function as a mask layer defining a pattern.
Preparation and development of various films used for patterning can include thermal treatment (e.g. baking). For example, a newly applied film can receive a post-application bake (PAB) to evaporate solvents and/or to increase structural rigidity or etch resistance. Also, a post-exposure bake (PEB) can be executed to set a given pattern to prevent further dissolving. Fabrication tools for coating and developing substrates typically include one or more baking modules. Some photolithography processes include coating a substrate with a thin film of bottom anti-reflective coating (BARC), followed by coating with a resist, and then exposing the substrate to a pattern of light as a process step for creating microchips. A relief pattern created can then be used as a mask or template for additional processing such as transferring the pattern into an underlying layer.
The minimum resolution attainable with a single lithographic exposure is limited, amongst other things, by the wavelength of light used (the so-called diffraction limit). Techniques such as immersion lithography can be utilized to lower the diffraction limit. Multiple patterning processes such as Self-Aligned Double Patterning (SADP) are increasingly being used for scaling semiconductor features below photolithographic limits. Multiple patterning processes can double pitch (for each additional patterning) and thus help to achieve feature sizes that are otherwise unattainable.
However, multiple patterning processes are frequently costly and complex. Additionally, multiple patterning process flows can be incompatible with high volume manufacturing. Further, many multiple patterning techniques require additional process steps such as etching, deposition, development, and treatments which also increase complexity and reduce throughput. Therefore, multiple pattern processes that reduce cost, reduce complexity, and/or increase compatibility are desirable.
In accordance with an embodiment of the present disclosure, a method for forming a patterned mask includes providing a patterned resist layer on a substrate and depositing an overcoat resist layer over the patterned resist layer. The patterned resist layer includes a first material including a first polymer. The overcoat resist layer includes a second material including a second polymer and a solubility shifting agent. The method further includes diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned resist layer and chemically transforming the exterior regions of the patterned resist layer to anti-spacer regions of a third material to a first depth into the patterned resist layer.
In accordance with an embodiment of the present disclosure, a method for forming a patterned mask includes providing a patterned resist layer on a substrate and depositing an overcoat resist layer over the patterned resist layer. The patterned resist layer includes a first material including a first polymer. The first material is soluble in a first solvent system. The first material is insoluble in a developer containing a polar solvent. The overcoat resist layer includes a second material including a solubility shifting agent and a second polymer with a functional group protected by a protecting group. The overcoat resist layer includes an overburden region overlying the patterned resist layer. The second material is soluble in a second solvent system that is less polar than the first solvent system. The second material is insoluble in the developer containing the polar solvent. The method further includes activating the solubility shifting agent to deprotect the functional group of the second polymer and chemically transforming at least the overburden region of the overcoat resist layer to a third material that has a non-zero dissolution rate in the developer containing the polar solvent, and diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned resist layer and chemically transforming the exterior regions of the patterned resist layer to anti-spacer regions of a fourth material to a first depth into the patterned resist layer. The fourth material is soluble in the developer containing the polar solvent. The fourth material has a dissolution rate in the developer that is faster than the non-zero dissolution rate of the third material in the developer.
In accordance with an embodiment of the present disclosure, a method for forming a patterned mask includes providing a patterned photoresist layer on a substrate and depositing an overcoat resist layer over the patterned photoresist layer. The patterned photoresist layer includes a first material including a first polymer. The overcoat resist layer includes a second material including a second polymer and a solubility shifting agent. The method further includes diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned photoresist layer and chemically transforming the exterior regions of the patterned photoresist layer to anti-spacer regions of a third material to a first depth into the patterned photoresist layer and removing the anti-spacer regions using a developer to form an anti-spacer pattern including remaining portions of the patterned photoresist layer and the overcoat resist layer. The anti-spacer pattern has openings to the substrate corresponding to the anti-spacer regions. At least part of the openings has a critical dimension corresponding to the first depth.
For a more complete understanding of example embodiments of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Referring now to the drawings, in which like reference numbers can be used herein to designate like or similar elements throughout the various views, illustrative and example embodiments are shown and described. The figures are not drawn to scale, and in some instances the drawings are exaggerated or simplified in places for illustrative purposes, including relative thicknesses and/or widths of layers and structures shown in the drawings. One of ordinary skill in the art can appreciate many possible applications and variations for other embodiments based on the following illustrative and example embodiments provided in the present disclosure.
In the present disclosure, terms such as “first”, “second”, “third”, “fourth”, and the like, can be used to describe various components, but the components are not necessarily limited by such terms, for example, regarding order, sequence, importance, or number of such components possible in an embodiment. Such terms can be used merely for the purpose of distinguishing one component from other components in a given embodiment or group of embodiments. Because semiconductor geometries and sizes can be so extremely small (e.g., on the order of 1 to 5 nm), the terms “film” and “layer” may be used interchangeably herein.
Ever continuous scaling can require improved patterning resolution. One approach is spacer technology to define a sub-resolution line feature via atomic layer deposition (ALD). One challenge, however, is that if the opposite tone feature is desired, using spacer techniques can involve a complex succession of operations, including over-coating with another material (an “overcoat”), using the spacer features as mandrels, chemical mechanical planarization (CMP), and reactive ion etch (RIE) to exhume the spacer material leaving a narrow trench, which can be costly. In such cases, spacer techniques can involve a complex and costly succession of steps, including over-coating with another material (an “overcoat”) using the spacer features as mandrels, chemical-mechanical planarization (CMP) to reveal the spacer features, and reactive ion etching (RIE) to remove the spacer material, leaving a narrow trench.
Anti-spacer technology is an alternate, self-aligned approach that can use the diffusion length of a reactive species across a boundary between an overcoat and an adjacent layer to define a critical dimension (CD), creating a narrow trench around the features of that adjacent layer after development of the overcoat or creating a narrow trench into the features of that adjacent layer after development of the diffusion changed regions. When generation of the reactive species is controlled spatially via exposure through a mask, finer features can be formed, such as a narrow slot contact. The CD itself can be tuned based on the physical and chemical properties of the reactive species (e.g., its molecular weight and affinity for interactions with the host material) and by modifying the bake temperature and bake time in a post exposure bake (PEB). As a result, anti-spacer techniques can enable patterning narrow slot-contact features at dimensions beyond the reach of advanced lithographic capabilities.
In some methods of forming an anti-spacer mask, an initial material property is being a so-called “protected” polymer that is not soluble in a typically-used developer, such as a quaternary ammonium hydroxide in an aqueous solution, or more specifically such as tetramethylammonium hydroxide (TMAH), for example. And then after a chemical transformation of the initial material to a given depth to form an anti-spacer region of a second material that is soluble in TMAH, such that the second material is a so-called “unprotected” polymer (with respect to TMAH). Next, when the wafer is developed using TMAH, the anti-spacer region can be removed to form openings, such as narrow line cuts, to form an anti-spacer mask. Accordingly, such recent methods of forming an anti-spacer mask typically start with a “protected” polymer (with respect to TMAH) that is converted to an “unprotected” polymer (with respect to TMAH) so that a development operation using TMAH as the developer will remove or etch away the “unprotected” polymer regions.
Recent methods of forming an anti-space mask deposit a separate overcoat containing a solubility shifting agent over a patterned photomask layer. The solubility shifting agent is then diffused into intermediate structures of the patterned photomask layer to form anti-spacer regions. In particular, the separate overcoat is not formulated to be a resist layer (e.g., remain on the substrate as part of a patterned mask, such as an etch mask). Instead, the separate overcoat is removed during a rinse process and a separate second resist layer is deposited over the patterned photomask layer including the anti-spacer regions. These additional steps add complexity to the method of forming the anti-spacer regions and decrease throughput.
In an embodiment of the present disclosure, an overcoat resist layer is used that includes an SSA. The SSA is diffused into an underlying patterned resist layer, such as using a baking process, to form anti-spacer regions in the patterned resist layer. Then, the anti-spacer regions are removed using a developer without removing the overcoat resist layer. That is, the overcoat resist layer that included the SSA remains on the substrate as structures that can be part of a patterned mask.
The formulation solvents used to overcoat the initial patterned layer must not dissolve the first resist. As an example, if the first resist is formulated in a polar solvent system (such as an ester solvent commonly used in resists for 193 nm lithography), the second resist may be formed in a nonpolar solvent system so as not to affect the first resist. Resist polymers commonly used in 248 or 13.5 nm lithography have such soluble characteristics (soluble in nonpolar solvents that will not dissolve thin films of typical 193 nm resists). In some cases, the second resist layer can include an overburden region overlying the “unprotected” polymer regions of the first patterned resist layer. For some solvent systems, this presents a challenge in the final development step to form the anti-spacer mask, such as where a polar developer (such as TMAH) is used to remove the “unprotected” polymer because the second resist is insoluble in the polar developer. That is, the overburden region can prevent the polar developer from reaching the ‘unprotected” polymer regions of the first patterned resist layer and the method of forming the anti-spacer mask can fail.
In an embodiment of the present disclosure, a method of forming an anti-spacer mask use specific formulations of the second polymer in the second resist layer that do not affect the first patterned resist layer, but that can also have a non-zero dissolution rate (e.g., 0<X<10 Å/s, such as preferably between 0.1 and 20 Å/s, more preferably between about 0.5 and 10 Å/s) in a polar developer used during an anti-spacer development step of a method of forming an anti-spacer mask. The second polymer can be deposited in a “protected” state that is soluble (e.g., highly soluble) in a nonpolar solvent system as part of a second resist layer over the first patterned resist layer. The “protected” second polymer can be deprotected using a solubility shifting agent (e.g., that does not affect the first resist) to form an “unprotected” second polymer that is soluble in the polar developer (i.e., has a non-zero dissolution rate).
The second polymer may include one or more types of repeating polymer units. At least one of the repeating polymer units has a functional group that at least partially controls the solubility of the second polymer relative to nonpolar and polar solvents. Particularly this functional group may tune the solubility of the polymer in the developer. The second polymer with the functional group exposed is initially insoluble with respect to nonpolar solvents (i.e., “unprotected” second polymer). A protecting group is attached to the functional group of the “unprotected” second polymer to shift the solubility of the second polymer so that it becomes soluble in nonpolar solvents (i.e., “protected” second polymer). Treatment of the “protected” second polymer with the solubility shifting agent (whether from the anti-spacer regions, included as part of the second resist, or a combination thereof) removes the protecting group (deprotects the second polymer) exposing the functional group and switching the solubility back to the initial state of being insoluble in nonpolar solvent (i.e., “deprotected” second polymer) and slightly soluble in the final developer.
In a method of forming an anti-spacer mask according to an embodiment of the present disclosure, an advantage of deprotecting the second polymer to remove the protecting group and expose the functional group is that the deprotected second polymer also has a non-zero dissolution rate in polar solvents. Specifically, the deprotected second polymer is soluble in a polar developer used to remove or etch away an anti-spacer region, such as a TMAH developer. This can allow an overburden region (e.g., a “thin” overburden layer, such as thinner than the anti-spacer region, for example) of a second resist layer including the second polymer to be dissolved without removing remaining portions of the second resist layer enabling the anti-spacer region to be removed (i.e., developed).
In some embodiments of the present disclosure, a method for forming a patterned mask can include providing a patterned resist layer on a substrate, where the patterned resist layer includes a first material that includes a first polymer, depositing an overcoat resist layer over the patterned resist layer, where the overcoat resist layer comprises a second material comprising a second polymer and a solubility shifting agent, and diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned resist layer and chemically transforming the exterior regions of the patterned resist layer to anti-spacer regions of a third material to a first depth into the patterned resist layer.
In some embodiments of the present disclosure, a method for forming a patterned mask can include providing a patterned resist layer on a substrate, where the patterned resist layer includes a first material that includes a first polymer. The first material is soluble in a first solvent system containing a first nonpolar solvent. However, the first material is insoluble in a developer containing a polar solvent. The method can further include depositing an overcoat resist layer over the patterned resist layer, where the overcoat resist layer comprises a second material comprising a solubility shifting agent and a second polymer with a functional group protected by a protecting group, and where the overcoat resist layer includes an overburden region overlying the patterned resist layer. The second material is soluble in a second solvent system containing a second nonpolar solvent, but the second material is insoluble in the developer containing the polar solvent.
The method for forming a patterned mask can further include activating the solubility shifting agent to deprotect the functional group of the second polymer and chemically transforming at least the overburden region of the overcoat resist layer to a third material that has a non-zero solubility (e.g., 0<X<10 Å/s, such as preferably between 0.1 and 20 Å/s, more preferably between about 0.5 and 10 Å/s) in the developer containing the polar solvent, and diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned resist layer and chemically transforming the exterior regions of the patterned resist layer to anti-spacer regions of a fourth material to a first depth into the patterned resist layer, where the fourth material is soluble (e.g. highly soluble) in the developer containing the polar solvent. The activating and diffusing may be performed concurrently and/or sequentially, and in any order.
In various embodiments, the second polymer can include para-hydroxystyrene, where a hydroxyl group of the para-hydroxystyrene is protected by a vinyl ether protecting group. In some embodiments, the second polymer includes other polymers, such as styrene and/or an acrylate (e.g., tert-butyl acrylate, n-butyl acrylate, a combination thereof, but may include other acrylates). In some embodiments, the polar developer is an aqueous base developer, and is a TMAH developer in one embodiment. In some embodiments, the first intermediate structure can be a patterned photoresist layer (e.g., exposed using EUV radiation and developed using an EUV photoresist developer). In some embodiments, the second intermediate structure can be a second resist layer deposited over the patterned photoresist layer.
The method can further include removing the anti-spacer regions using a developer to form an anti-spacer pattern comprising remaining portions of a first intermediate structure (e.g., a patterned resist layer) and a second intermediate structure (e.g., an overcoat resist layer including the second polymer). The anti-spacer pattern has openings (e.g., mask openings) to the substrate corresponding to the anti-spacer regions, where at least part of the openings has a critical dimension corresponding to the first depth. The method can further include etching the substrate through the mask openings to form openings in the substrate having the substantially the same critical dimension.
Some example embodiments of the present disclosure are described in detail with reference to
Referring to
The second intermediate structure 21 can include an SSA 15 (a solubility shifting agent) therein. The SSA 15 can be selected so that it requires additional activation energy to generate a catalyst portion of the SSA 15 (e.g., thermal energy provided during diffusion or other energy, such as from actinic radiation). The second intermediate structure 21 interfaces with the first intermediate structure 11 at least at an exterior region 31 (at a perimeter region of the first intermediate structure 11). The second intermediate structure 21 has a material overburden 92 that overlies the first intermediate structure 11 so that top surfaces of the first intermediate structure 11 are adjacent to the second intermediate structure 21.
The second intermediate structure 21 can include a second polymer 81 (i.e., a second polymer used as a second resist), which may be any standard polymer used in resist materials (e.g., that also that meets the solubility requirements of a given implementation). The SSA 15 may be selected so that it does not substantially affect the solubility of the second polymer 81 when formulated together with the second polymer 81 or when the SSA 15 is activated (e.g., during diffusion or during a separate activation process). Alternatively, the SSA 15 and the second polymer 81 may be selected so that activation of the SSA 15 also shifts the solubility of the second polymer 81, such as from substantially insoluble in a developer to having a non-zero solubility in the developer.
For example, the first polymer 41 and/or the second polymer 81 of an embodiment of the present disclosure can be composed of monomers including vinyl monomers such as styrene, acrylate, methacrylate, norbornene, or combinations thereof, or other monomers that can be polymerized into a polymer. The first polymer 41 can also include one or more monomers that include reactive functional groups including alcohols or carboxylic acids. In some embodiments, the reactive functional group can include a hydroxy-aryl group. In some embodiments, the first polymer 41 can include para-hydroxystyrene. In some embodiments, a first polymer 41 can include a carboxylic acid functionality, such as acrylic acid or methacrylic acid. In some embodiments, the first polymer 41 can include an alcohol functionality or an acrylate or methacrylate functionalized with a carbohydrate, for example. In some cases, such as the specific example described using
In some embodiments, the SSA 15 can be formed in situ during the deposition of the second intermediate structure 21. In such case, the SSA 15 can be evenly distributed throughout the second intermediate structure 21, for example, but not necessarily. In some embodiments, the second intermediate structure 21 can be deposited without the SSA and the SSA 15 can be put into the second intermediate structure 21 thereafter. For example, in some embodiments, the SSA 15 can be implanted or diffused into the second intermediate structure 21.
The exterior region 31 of the first intermediate structure 11 including the first material can be adjacent and in direct physical contact with the second intermediate structure 21 containing the SSA 15. In some embodiments, there can be one or more intervening layers (not shown in the drawings) between the first intermediate structure 11 and the second intermediate structure 21 at the exterior region 31 provided that certain materials can diffuse through such one or more intervening layers (diffusion discussed next).
In the present disclosure, for an embodiment, the term “substrate” (e.g., substrate 12) can be used generally and as a shorthand description for an underlying structure that can include any combination of layers, materials, structures, devices, and a wafer of any suitable structure. For example, the substrate 12 of an embodiment can include one or more bottom anti-reflective coating (BARC) layers, one or more developable BARC (dBARC) layers, one or more etch stop layers, one or more resist layers, one or more hard mask layers, one or more dielectric layers, one or more intermetal dielectric layers, one or more conductive lines/layers/interconnects, one or more transistor structures, one or more capacitor structures, one or more resistor structures, one or more inductor structures, one or more memory cells, or any combination thereof.
Referring to
In the drawings for the present disclosure (e.g.,
While describing the example embodiments of the present disclosure, the term “solubility shifting agent” or “SSA” can refer to a substance in a general sense that if not already a catalyst agent itself, it can generate and/or can transform (e.g., by heat and/or certain radiation of light) to a catalyst agent and/or constituent parts that includes a catalyst agent that can be used in a chemical reaction to shift or change a solubility property of a material.
In an embodiment, an SSA 15 can include an agent-generating ingredient that, in response to a suitable agent-activation trigger (e.g., heat and/or radiation), generates a solubility-changing chemical (e.g., an acid). Example agent-generating ingredients can include a thermal-acid generator (TAG) that is configured to generate an acid in response to heat or a photo-acid generator (PAG) that is configured to generate an acid in response to actinic radiation. The SSA 15 or a catalyst portion of the SSA 15 can react directly with the polymer 41 to produce the converted region 53.
For example, the chemical transforming of the exterior region 31 of the first intermediate structure 11 can include diffusing acid from the second intermediate structure 21 into the exterior region 31 of the first intermediate structure 11 to increase solubility or change/shift solubility of the exterior region 31 for a given developer (e.g., the developer containing a polar solvent) such that the exterior region 31 of the first intermediate structure 11 becomes the converted region 53 of a second/different material.
For example, the second intermediate structure 21 can include a free acid as an SSA 15. During a baking operation, the free acid (represented as H+ in
As another example, the second intermediate structure 21 can include a TAG as an agent-generating ingredient for the SSA 15. Baking the substrate 12 (e.g., a wafer) can cause the TAG to generate a solubility-changing agent (e.g., acid, represented as H+ in
As another example, the second intermediate structure 21 can include a PAG as an agent-generating ingredient for the SSA 15. The second intermediate structure 21 can be exposed to a radiation (e.g., actinic radiation) that can be performed prior to baking the wafer. Such exposure to radiation can cause the PAG to generate a solubility-changing agent (e.g., acid, represented as H+ in
In an embodiment, a baking process for forming the converted region 53 of the second material can be a thermal process that is performed by heating the substrate 12 in a process chamber to a temperature between 50° C. and 250° C., for example, or between 60° C. and 140° C. in certain embodiments, in vacuum or under a gas flow. In a particular example, the substrate 12 can be baked for a duration in a range from 1 to 3 minutes. The bake conditions can be selected to promote the diffusion of the solubility-changing agent (and possibly generation of the solubility-changing agent from an agent generating ingredient of the SSA 15 in the second intermediate structure 21) and associated change in solubility of the perimeter regions (exterior region 31) of the first intermediate structure 11 to a target first depth FD (see, e.g.,
The first depth FD can be tuned by parameters of the baking process (such as, for example, a bake temperature and a bake duration) and material parameters (such as, for example, a polymer composition of the first intermediate structure 11, and an acid composition and an acid concentration from the SSA 15 in the second intermediate structure 21). Some example materials that can be used for the SSA 15 or generated from the SSA 15 as a catalyst for the chemical reaction to shift/change the solubility of the exterior region 31 to the converted region 53 of the second material in an embodiment will be described later in the present disclosure.
In
In the present disclosure, the terms “soluble” and “insoluble” are used in a relative sense, not in an absolute sense. That is, the term “insoluble” as used herein refers to one subject material being dissolved or removed much faster and much more effectively compared to another adjacent non-subject material, such as an order of magnitude or more faster and more effectively, and not to necessarily be that the other adjacent non-subject material experiences no dissolving or removal, but rather that the subject material is removed so much faster and more effectively that the subject material can be dissolved and removed sufficiently or to its full extent while only a small amount or even only a negligible amount of the other adjacent non-subject material is dissolved and removed, such that most of or almost all of the other adjacent non-subject material at the stopping point of the dissolving and removing of the subject material, as can be apparent to one of ordinary skill in the art pertaining to the present disclosure.
The critical dimension CD is not necessarily equal to the first depth FD in some embodiments, but can be derived from and dependent upon the first depth FD for which most of or all of the catalyst of/from the SSA 15 diffused into the first intermediate structure 11. Thus, a critical dimension CD of the mask openings 62 can be adjusted, tuned, and specified based on parameters (e.g., temperature, bake time, radiation energy, exposure time, etc.) for the process of diffusing the catalyst of/from the SSA 15 and/or the process of causing the chemical reaction to form the second material of the converted region 53, as well as other factors, such as the choice of the substance for the catalyst of/from the SSA 15, the first material of the first intermediate structure 11 (e.g., choice of photoresist material(s) and/or other additives), the choice of the first polymer 41 of the first intermediate structure 11, other additives/substances present also in the first intermediate structure 11, or any suitable combination thereof.
Although only two mask openings 62 are shown in
Referring to
Referring to
The second polymer 81 can also be affected by the SSA 15. For example, during the diffusion process, the catalyst portion of the SSA 15 may deprotect the second polymer (i.e., remove the protecting group from the functional group of the second polymer) and shift the solubility of the second polymer. Alternatively, the SSA 15 may be activated separately from the diffusion process before, during, or after the diffusion, such as by exposing the SSA 15 to actinic radiation. In one embodiment, the substrate is exposed to a flood of actinic radiation to activate the SSA 15.
The deprotection of the second polymer 81 results in a deprotected second polymer 82. In some embodiments, the deprotected second polymer is soluble in a polar solvent (e.g., a developer containing a polar solvent). Specifically, the second polymer 81 can have a substantially zero solubility in a polar solvent (insoluble) and the second polymer 82 can have a nonzero solubility in a polar solvent (soluble). In the specific example shown, the solubility of the entire second intermediate structure is shifted. In other embodiments, substantially only the solubility of the material overburden 92 overlying the converted region 53 is shifted.
Because the initial unprotected state of the second polymer 81 is insoluble in nonpolar solvent, the initial state is not suitable for use as the second polymer 81 in a second intermediate structure, such as a second resist layer used to form an anti-spacer mask when the first intermediate structure 11 is a photoresist layer that is patterned (i.e., developed) with certain types of developers. For example, when the first intermediate structure 11 is a photoresist layer patterned using an EUV resist, the first polymer of the first intermediate structure 11 is soluble in nonpolar solvent systems. In order for the third material including the deprotected second polymer 82 to not interfere with the patterned photoresist layer, it can also be selected to be soluble in a nonpolar solvent system. However, the unprotected initial state of the second polymer 81 is insoluble in nonpolar solvent.
Protecting the functional group FG with a protecting group PG shifts the solubility of the second polymer 81. Specifically, the protected second polymer 81 is soluble in nonpolar solvent. For this reason, before including the second polymer 81 in a nonpolar solvent system for deposition as part of the third material of a second intermediate structure 21 (such as a second resist layer), the functional group FG of the second polymer 81 is protected using the protecting group PG. An SSA (such as the SSA 15 included in the second intermediate structure 21) can then be used to cleave the protecting group PG from the functional group FG to form a deprotected second polymer 82 that is soluble in polar solvent. As previously discussed, the solubility of the deprotected second polymer 82 may have relatively weak solubility compared to the solubility of a converted region 53 (e.g., an anti-spacer region) of an adjacent first intermediate structure 11. However, the non-zero dissolution rate (e.g., 0<X<10 Å/s, such as preferably between 0.1 and 20 Å/s, more preferably between about 0.5 and 10 A/s) of the deprotected second polymer 82 in a polar solvent, such as a polar developer like a TMAH developer, is sufficient to allow a material overburden 92 of a second intermediate structure 21 to be removed so that an underlying converted region 53 can be removed with the polar solvent.
As an example, the first material of a first intermediate structure 11 may be a photoresist that includes a polymer (e.g., a first polymer 41), a photoacid generator, and a solvent. In one or more embodiments, the polymer may be any standard polymer typically used with photoresist material and may particularly be a polymer having acid-labile groups. Specifically, the first polymer 41 may be formed from a vinyl aromatic-based polymer, (which may be used for various photoresists, such as for KrF and EUV photoresists), and the resist may be developed as a positive tone development (PTD) resist. In this case a solvent system may be used that includes two or more types of nonpolar solvent. In various embodiments, the solvent system includes one or more nonpolar organic solvents. The term “nonpolar organic-based” may refer to having greater than 50 wt % of combined nonpolar organic solvents based on total solvents of the solubility shifting agent composition, more typically greater than 70 wt %, greater than 85 wt % or 100 wt %, combined nonpolar organic solvents, based on total solvents of the composition of the first material. The nonpolar organic solvents are typically present in the solvent system in a combined amount of from 70 to 98 wt %, preferably 80 to 95 wt %, more preferably from 85 to 98 wt %, based on the solvent system.
So in other words, in order to not affect the first resist, the second resist must also be formulated in a nonpolar solvent. This presents a challenge for the final develop step when the solubility-shifted region (converted region 53) of the first intermediate structure 11 (e.g., of a patterned photoresist layer) is removed. A common developer for the final develop process is an aqueous base developer, one specific example of which is 0.26 N TMAH (other aqueous base developer as also discussed throughout this disclosure). This developer is very polar, and thus opposite of the nonpolar solvent used in the second resist formulation. This presents a major challenge, as the desirable material must have both excellent solubility in a nonpolar solvents but then a low but non-zero dissolution rate in the developer.
In various embodiments, the repeated unit P1 of the second polymer 81 is a standard polymer typically used in photoresist material and is a polymer that includes acid-labile groups in some embodiments. In some embodiments, the repeated unit P1 may be a monomer including para-hydroxystyrene, styrene, tert-butyl acrylate (PHS/S/TBA), and combinations thereof. In another embodiment, the repeated unit P1 may be a monomer including para-hydroxystyrene, styrene, n-butyl acrylate (PHS/S/NBA), and combinations thereof. Some embodiments of the repeated unit P1 may include both tert-butyl acrylate and n-butyl acrylate. In some embodiments, the repeated unit P1 is or includes other monomers, such as other vinyl aromatic monomers, acrylic acid, methacrylic acid, other acrylates or methacrylates such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, another acrylate or methacrylate functionalized with a carbohydrate, norbornene, or any combination thereof.
Functional groups, such as the hydroxyl group (—OH) of para-hydroxystyrene may be protected with a tert-butyloxycarbonyl protecting group or an acetal protecting group. Such protecting group may alter the reactivity and solubility of the polymer included in the second resist. As will be appreciated by one having ordinary skill in the art, various protecting groups may be used for this reason. Acid-labile groups include, for example: tertiary alkyl ester groups, secondary or tertiary aryl ester groups, secondary or tertiary ester groups having a combination of alkyl and aryl groups, tertiary alkoxy groups, acetal groups, or ketal groups. Acid-labile groups are also commonly referred to in the art as “acid-decomposable groups”, “acid-cleavable groups,” “acid-cleavable protecting groups,” “acid-labile protecting groups,” “acid leaving groups,” and “acid-sensitive groups.”
In the unprotected state, the second polymer 81 is again insoluble in nonpolar solvent (rendering it incompatible for use with certain developers, such as EUV developers). Protecting the hydroxyl group with a vinyl ether protecting group shifts the solubility of the second polymer 81 so that it becomes soluble in nonpolar solvent and can be deposited over a patterned photoresist layer, for example. The introduction of an SSA removes the vinyl ether protecting group forming a deprotected second polymer 82 that is soluble in polar solvent by virtue of the hydroxyl group of the para-hydroxystyrene units again being exposed.
The method can further include depositing an overcoat resist layer over the patterned resist layer, where the overcoat resist layer includes a second material that includes a solubility shifting agent and a second polymer with a functional group protected by a protecting group, where the overcoat resist layer includes an overburden region overlying the patterned resist layer, where the second material is soluble in a second solvent system that is less polar than the first solvent system, and where the second material is insoluble in the developer containing the polar solvent (box 702).
The method can further include activating the solubility shifting agent to deprotect the functional group of the second polymer and chemically transforming at least the overburden region of the overcoat resist layer to a third material that has a non-zero dissolution rate in the developer containing the polar solvent (box 703), and diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned resist layer and chemically transforming the exterior regions of the patterned resist layer to anti-spacer regions of a fourth material to a first depth into the patterned resist layer, where the fourth material is soluble in the developer containing the polar solvent, the fourth material having a dissolution rate in the developer that is faster than the non-zero dissolution rate of the third material in the developer (box 704).
The method can further include diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned photoresist layer and chemically transforming the exterior regions of the patterned photoresist layer to anti-spacer regions of a third material to a first depth into the patterned photoresist layer (box 804). Optionally, the solubility shifting agent can be activated before after or during diffusion to deprotect a functional group of the second polymer and chemically transform at least an overburden region of the overcoat resist layer to a third material that has a non-zero dissolution rate in a developer (box 803).
The method can further include removing the anti-spacer regions using a developer to form an anti-spacer pattern comprising remaining portions of the patterned photoresist layer and the overcoat resist layer having openings to the substrate corresponding to the anti-spacer regions, wherein at least part of the openings has a critical dimension corresponding to the first depth (box 805).
For describing some example materials that can be implemented and used in an embodiment of the present disclosure, some example definitions will be provided next. These definitions are intended to supplement and illustrate, not preclude, definitions known to those of skill in the art, as can be apparent to one of ordinary skill in the art to which the present disclosure pertains.
The term “independently selected” as used herein can indicate that the R groups, such as, R1, R2, R3, R4, and R5 can be identical or different (e.g., R1, R2, R3, R4, and R5 may all be substituted alkyls or R1 and R2 may be a substituted alkyl and R3 may be an aryl, etc.). Use of the singular can include use of the plural, and vice versa (e.g., a hexane solvent can include hexanes). A named R group can generally have the structure that is recognized in the art as corresponding to R groups having that name.
The term “aliphatic” can refer to a non-aromatic saturated or unsaturated straight or branched hydrocarbon radical of from 1 to 40 carbon atoms or from 1 to 18 carbon atoms.
By “substituted” as in “substituted aliphatic moiety,” “substituted aryl,” “substituted alkyl,” and “substituted alkenyl,” as alluded to in some of the aforementioned definitions, can be indicate that in the hydrocarbyl, hydrocarbylene, alkyl, alkenyl, aryl or other moiety, at least one hydrogen atom bound to a carbon atom is replaced with one or more substituents that are groups such as hydroxyl, alkoxy, alkylthio, amino, halo, and silyl, to name a few. When the term “substituted” appears prior to a list of possible substituted groups, it can be intended that the term applies to every member of that group. For example, the phrase “substituted alkyl, alkenyl, and alkynyl” can be interpreted as “substituted alkyl, substituted alkenyl, and substituted alkynyl.” Similarly, “optionally substituted alkyl, alkenyl, and alkynyl” can be interpreted as “optionally substituted alkyl, optionally substituted alkenyl, and optionally substituted alkynyl.”
The term “substitution” can indicate each hydrogen atom (H) bonded to a carbon atom or heteroatom of a corresponding unsubstituted compound or functional group is replaced by a substituent (e.g., Rs). The term “polysubstitution” can indicate each of at least two, but not all, hydrogen atoms bonded to carbon atoms or heteroatoms of a corresponding unsubstituted compound or functional group is replaced by a substituent. The (C1-C18)alkylene and (C1-C8)alkylene substituents can be especially useful for forming substituted chemical groups that are bicyclic or tricyclic analogs of corresponding monocyclic or bicyclic unsubstituted chemical groups, for example.
The term “(C1-C40)hydrocarbyl” can refer to a hydrocarbon radical of from 1 to 40 carbon atoms and the term “(C1-C40)hydrocarbylene” can refer to a hydrocarbon diradical of from 1 to 40 carbon atoms, in which each hydrocarbon radical and diradical independently is aromatic (6 carbon atoms or more) or non-aromatic, saturated or unsaturated, straight chain or branched chain, cyclic (including mono- and poly-cyclic, fused and non-fused polycyclic, including bicyclic; 3 carbon atoms or more) or acyclic, or a combination of two or more thereof, and each hydrocarbon radical and diradical independently can be the same as or different from another hydrocarbon radical and diradical, respectively, and independently can be unsubstituted or substituted by one or more Rs.
In the present disclosure, a (C1-C40)hydrocarbyl independently can be an unsubstituted or substituted (C1-C40)alkyl, (C3-C40)cycloalkyl, (C3-C20)cycloalkyl-(C1-C20)alkylene, (C6-C40)aryl, or (C6-C20)aryl-(C1-C20)alkylene. In some embodiments, each of the aforementioned (C1-C40)hydrocarbyl groups independently has a maximum of 20 carbon atoms (i.e., (C1-C20)hydrocarbyl) and in other embodiments, a maximum of 12 carbon atoms, for example.
The terms “(C1-C40)alkyl” and “(C1-C18)alkyl” can refer to a saturated straight or branched hydrocarbon radical of from 1 to 40 carbon atoms or from 1 to 18 carbon atoms, respectively, that is unsubstituted or substituted by one or more Rs. Examples of unsubstituted (C1-C40)alkyl are: unsubstituted (C1-C20)alkyl; unsubstituted (C1-C10)alkyl; unsubstituted (C1-C5)alkyl; methyl; ethyl; 1-propyl; 2-propyl; 1-butyl; 2-butyl; 2-methylpropyl; 1,1-dimethylethyl; 1-pentyl; 1-hexyl; 1-heptyl; 1-nonyl; and 1-decyl. Examples of substituted (C1-C40)alkyl are substituted (C1-C20) alkyl, substituted (C1-C10)alkyl, trifluoromethyl, and (C45)alkyl. The (C45)alkyl is, for example, a (C27-C40)alkyl substituted by one Rs, which is a (C1-C5)alkyl, respectively. In some embodiments, each (C1-C5)alkyl independently is methyl, trifluoromethyl, ethyl, 1-propyl, 1-methylethyl, or 1,1-dimethylethyl, for example.
The term “(C6-C40)aryl” can refer to an unsubstituted or substituted (by one or more Rs) mono-, bi-, or tricyclic aromatic hydrocarbon radical of from 6 to 40 carbon atoms, of which at least from 6 to 14 of the carbon atoms are aromatic ring carbon atoms, and the mono-, bi-, or tricyclic radical comprises 1, 2 or 3 rings, respectively; wherein the 1 ring is aromatic and the 2 or 3 rings independently are fused or non-fused and at least one of the 2 or 3 rings is aromatic. Examples of unsubstituted (C6-C40)aryl are: unsubstituted (C6-C20)aryl unsubstituted (C6-C18)aryl; 2-(C1-C5)alkyl-phenyl; 2,4-bis(C1-C5)alkyl-phenyl; phenyl; fluorenyl; tetrahydrofluorenyl; indacenyl; hexahydroindacenyl; indenyl; dihydroindenyl; naphthyl; tetrahydronaphthyl; and phenanthrene. Examples of substituted (C6-C40)aryl are: substituted (C1-C20)aryl; substituted (C6-C18)aryl; 2,4-bis[(C20)alkyl]-phenyl; polyfluorophenyl; pentafluorophenyl; and fluoren-9-one-1-yl.
The term “(C3-C40)cycloalkyl” can refer to a saturated cyclic hydrocarbon radical of from 3 to 40 carbon atoms that is unsubstituted or substituted by one or more Rs. Other cycloalkyl groups (e.g., (C3-C12)alkyl) can be defined in an analogous manner. Examples of unsubstituted (C3-C40)cycloalkyl are: unsubstituted (C3-C20)cycloalkyl, unsubstituted (C3-C10)cycloalkyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl. Examples of substituted (C3-C40)cycloalkyl are: substituted (C3-C20)cycloalkyl, substituted (C3-C10)cycloalkyl, cyclopentanon-2-yl, and 1-fluorocyclohexyl.
Examples of (C1-C40)hydrocarbylene are: unsubstituted or substituted (C6-C40)arylene, (C3-C40)cycloalkylene, and (C1-C40)alkylene (e.g., (C1-C20)alkylene). In some embodiments, the diradicals are a same carbon atom (e.g., —CH2-) or on adjacent carbon atoms (i.e., 1,2-diradicals), or are spaced apart by one, two, or more intervening carbon atoms (e.g., respective 1,3-diradicals, 1,4-diradicals, etc.), for example. Some embodiments incorporate a 1,2-, 1,3-, 1,4-, or an alpha, omega-diradical, and others a 1,2-diradical, for example. The alpha, omega-diradical can be a diradical that has maximum carbon backbone spacing between the radical carbons. Some embodiments can incorporate a 1,2-diradical, 1,3-diradical, or 1,4-diradical version of (C6-C18)arylene, (C3-C20)cycloalkylene, or (C2-C20)alkylene.
The term “(C1-C40)alkylene” can refer to a saturated straight chain or branched chain diradicals (i.e., the radicals are not on ring atoms) of from 1 to 40 carbon atoms that is unsubstituted or substituted by one or more Rs. Examples of unsubstituted (C1-C40)alkylene are: unsubstituted (C1-C20)alkylene, including unsubstituted 1,2-(C2-C10)alkylene; including unsubstituted 1,3-(C3-C10)alkylene; 1,4-(C4-C10)alkylene; —C—, —CH2CH2-, —(CH2)-, —CH2CHCH3, —(CH2)4-, —(CH2)5-, —(CH2)6-, —(CH2)7-, —(CH2)8-, and —(CH2)4C(H)(CH3)-. Examples of substituted (C1-C40)alkylene are: substituted (C1-C20)alkylene, —CF2-, —C(O)—, and —(CH2)14C(CH3)2(CH2)5-(i.e., a 6,6-dimethyl substituted normal-1,20-eicosylene). As mentioned previously two Rs may be taken together to form a (C1-C18)alkylene, examples of substituted (C1-C40)alkylene also include 1,2-bis(methylene)cyclopentane, 1,2-bis(methylene)cyclohexane, 2,3-bis(methylene)-7,7-dimethyl-bicyclo[2.2.1]heptane, and 7,3-bis(methylene)bicyclo[2.2.2]octane.
The term “(C3-C40)cycloalkylene” can refer to a cyclic diradical (i.e., the radicals are on ring atoms) of from 3 to 40 carbon atoms that is unsubstituted or substituted by one or more Rs.
The term “heteroatom,” “heterohydrocarbon’ can refer to a molecule or molecular framework in which one or more carbon atoms are replaced with an atom other than carbon or hydrogen. The term “(C1-C40)heterohydrocarbyl” can refer to a heterohydrocarbon radical of from 1 to 40 carbon atoms and the term “(C1-C40)heterohydrocarbylene” can refer to a heterohydrocarbon diradical of from 1 to 40 carbon atoms, and each heterohydrocarbon independently has one or more heteroatoms, for example O, S, S(O), S(O)2, Si(RC)2, P(RP), and N(RN). Independently each RC is unsubstituted (C1-C18)hydrocarbyl, each RP is unsubstituted (C1-C19)hydrocarbyl, and each RN is unsubstituted (C1-C18)hydrocarbyl or absent. When RN is absent then N comprises —N═. The heterohydrocarbon radical, and each of the heterohydrocarbon diradicals, independently is on a carbon atom or heteroatom thereof, and in most embodiments, it is on a carbon atom when bonded to a heteroatom formula (I) or to a heteroatom of another heterohydrocarbyl or heterohydrocarbylene. Each (C1-C40)heterohydrocarbyl and (C1-C40)heterohydrocarbylene independently is unsubstituted or substituted (by one or more Rs), aromatic or non-aromatic, saturated or unsaturated, straight chain or branched chain, cyclic (including mono- and poly-cyclic, fused and non-fused polycyclic) or acyclic, or a combination of two or more thereof; and each is respectively the same as or different from another.
In some embodiments, the (C1-C40)heterohydrocarbyl independently can be unsubstituted or substituted (C1-C40)heteroalkyl, (C1-C40)hydrocarbyl-O—, (C1-C40)hydrocarbyl-S—, (C1-C40)hydrocarbyl-S(O)—, (C1-C40)hydrocarbyl-S(O)2-, (C1-C40)hydrocarbyl-Si(Rc)2-, (C1-C40)hydrocarbyl-N(RN)—, (C1-C40)hydrocarbyl-P(RP)—, (C2-C40)heterocycloalkyl, (C2-C19)heterocycloalkyl-(C1-C20)alkylene, (C3-C20cycloalkyl-(C1-C19)heteroalkylene, (C2-C19)heterocycloalkyl-(C1-C20)heteroalkylene, (C1-C40)heteroaryl, (C1-C19)heteroaryl-(C1-C20)alkylene, (C6-C20)aryl-(C1-C19)heteroalkylene, or (C1-C19)heteroaryl-(C1-C20)heteroalkylene, for example.
The term “(C4-C40)heteroaryl” can refer to an unsubstituted or substituted (by one or more Rs) mono-, bi-, or tricyclic heteroaromatic hydrocarbon radical of from 1 to 40 total carbon atoms and from 1 to 4 heteroatoms, and the mono-, bi-, or tricyclic radical can include 1, 2, or 3 rings, respectively, wherein the 2 or 3 rings independently can be fused or non-fused and at least one of the 2 or 3 rings can be heteroaromatic. Other heteroaryl groups (e.g., (C4-C12)heteroaryl) can be defined in an analogous manner. The monocyclic heteroaromatic hydrocarbon radical can be a 5-membered or 6-membered ring. The 5-membered ring can have from 2 to 4 carbon atoms and from 3 to 1 heteroatoms, respectively, each heteroatom being 0, S, N, or P. Examples of 5-membered ring heteroaromatic hydrocarbon radical are: pyrrol-1-yl; pyrrol-2-yl; furan-3-yl; thiophen-2-yl; pyrazol-1-yl; isoxazol-2-yl; isothiazol-5-yl; imidazol-2-yl; oxazol-4-yl; thiazol-2-yl; 1,2,4-triazol-1-yl; 1,3,4-oxadiazol-2-yl; 1,3,4-thiadiazol-2-yl; tetrazol-1-yl; tetrazol-2-yl; and tetrazol-5-yl. The 6-membered ring can have 4 or 5 carbon atoms and 2 or 1 heteroatoms, the heteroatoms being N or P. Examples of 6-membered ring heteroaromatic hydrocarbon radical are: pyridine-2-yl; pyrimidin-2-yl; and pyrazin-2-yl. The bicyclic heteroaromatic hydrocarbon radical can be a fused 5,6- or 6,6-ring system. Examples of the fused 5,6-ring system bicyclic heteroaromatic hydrocarbon radical are: indol-1-yl; and benzimidazole-1-yl. Examples of the fused 6,6-ring system bicyclic heteroaromatic hydrocarbon radical are: quinolin-2-yl; and isoquinolin-1-yl. The tricyclic heteroaromatic hydrocarbon radical can be a fused 5,6,5-; 5,6,6-; 6,5,6-; or 6,6,6-ring system. An example of the fused 5,6,5-ring system is 1,7-dihydropyrrolo[3,2-f]indol-1-yl. An example of the fused 5,6,6-ring system is 1H-benzo[f]indol-1-yl. An example of the fused 6,5,6-ring system is 9H-carbazol-9-yl. An example of the fused 6,5,6-ring system is 9H-carbazol-9-yl. An example of the fused 6,6,6-ring system is acrydin-9-yl.
The aforementioned heteroalkyl and heteroalkylene groups can be saturated straight or branched chain radicals or diradicals, respectively, containing (C1-C40) carbon atoms, or fewer carbon atoms and one or more of the heteroatoms Si(Rc)2, P(RP), N(RN), N, O, S, S(O), and S(O)2 as defined above, wherein each of the heteroalkyl and heteroalkylene groups independently can be unsubstituted or substituted by one or more Rs.
Examples of unsubstituted (C2-C40)heterocycloalkyl are: unsubstituted (C2-C20)heterocycloalkyl, unsubstituted (C2-C10)heterocycloalkyl, aziridin-1-yl, oxetan-2-yl, tetrahydrofuran-3-yl, pyrrolidin-1-yl, tetrahydrothiophen-S,S-dioxide-2-yl, morpholin-4-yl, 1,4-dioxan-2-yl, hexahydroazepin-4-yl, 3-oxa-cycloodyl, 5-thio-cyclononyl, and 2-aza-cyclodecyl.
The term “halogen atom” can refer to fluorine (F), chlorine atom (C1), bromine atom (Br), or iodine atom (I) radical. The terms “halide” can refer to fluoride (F—), chloride (Cl—), bromide (Br—), or iodide (I—) anion.
The term “saturated” can refer to lacking carbon-carbon double bonds, carbon-carbon triple bonds, and (in heteroatom-containing groups) carbon-nitrogen, carbon-phosphorous, and carbon-silicon double bonds. Where a saturated chemical group is substituted by one or more substituents Rs, one or more double and/or triple bonds optionally may or may not be present in substituents Rs. The term “unsaturated” can refer to containing one or more carbon-carbon double bonds, carbon-carbon bonds, and (in heteroatom-containing groups) carbon-nitrogen, carbon-phosphorous, and carbon-silicon double bonds, not including any such double bonds that may be present in substituents Rs, if any, or in (hetero) aromatic rings, if any.
In an embodiment of present disclosure, a photoresist composition may be used to form a first intermediate structure 11 and can be a chemically amplified photosensitive composition that can include a first polymer 41, a photoacid generator, a solvent, and may also contain additional, optional components, including a quencher. Using particular photoresist compositions of an embodiment of the present disclosure can achieve notably improved lithographic performance, such as better contrast, higher resolution, and reduced roughness of resolved patterns. For example, the first polymer 41 is an EUV photoresist in one embodiment.
Next, some example materials that can be implemented and used for a first polymer 41 and/or a second polymer 81 referenced above while describing the example embodiments of
A first polymer 41 and/or a second polymer 81 of an embodiment of the present disclosure can be a homopolymer or a copolymer having a plurality of distinct repeat units (also referred to as monomers), for example, two, three, four, or more distinct repeat units. A first polymer 41 and/or a second polymer 81 can be composed of monomers including vinyl monomers such as styrene, acrylate, methacrylate, norbornene, or combinations thereof, or other monomers that can be polymerized into a polymer. The repeat units of a first polymer 41 and/or a second polymer 81 can be all formed from (meth)acrylate monomers, can be all formed from (vinyl) aromatic monomers, or can be all formed from (meth)acrylate monomers and (vinyl) aromatic monomers, for example.
A first polymer 41 and/or a second polymer 81 can include one or more monomers that include reactive functional groups. In one embodiment, a first polymer 41 and/or a second polymer 81 can include an ester functional group that can react with an acid so that it is converted into a carboxylic acid functional group (e.g., shifting the solubility of the material, such as allowing dissolution in an aqueous base, such as aqueous TMAH, for example). In some embodiments, the reactive functional group can include a hydroxy-aryl group. In some embodiments, a first polymer 41 and/or a second polymer 81 can include para-hydroxystyrene. In some embodiments, a first polymer 41 and/or a second polymer 81 can include a carboxylic acid functionality, such as acrylic acid or methacrylic acid.
A first polymer 41 and/or a second polymer 81 can have a repeating unit having an alicyclic hydrocarbon structure and/or an aromatic ring structure that does not have a reactive functional group. In some embodiments, a first polymer 41 can include one or more monomers of Formula 1:
In Formula 1, R1 can be hydrogen, fluorine, cyano, substituted or unsubstituted C1-10 alkyl, or substituted or unsubstituted C1-10 fluoroalkyl. In Formula 1, R1 can be hydrogen, fluorine, or substituted or unsubstituted C1-5 alkyl, typically methyl. In Formula 1, L1 can be a single bond or a divalent linking group. For example, L1 can be a single bond or a divalent linking group including one or more of substituted or unsubstituted C1-30 alkylene, substituted or unsubstituted C1-30 heteroalkylene, substituted or unsubstituted C3-30 cycloalkylene, substituted or unsubstituted C1-30 heterocycloalkylene, substituted or unsubstituted C6-30 arylene, or substituted or unsubstituted C4-30 heteroarylene, wherein L1 optionally can further include one or more groups chosen, for example, from —O—, —C(O)—, —C(O)—O—, —S—, —S(O)2-, and —N(R3)—S(O)2-, wherein R3 can be hydrogen, substituted or unsubstituted C1-20 alkyl, substituted or unsubstituted C3-20 cycloalkyl, or substituted or unsubstituted C1-20 heterocycloalkyl. In Formula 1, R2 can be a monocyclic, polycyclic, or fused polycyclic C4-20 lactone-containing group, or a monocyclic, polycyclic, or fused polycyclic C4-20 sultone-containing group.
The form of a first polymer 41 and/or a second polymer 81 in an embodiment of the present disclosure can be any form of a random type, a block type, a comb type, and a star type. When a first polymer 41 and/or a second polymer 81 of an embodiment includes more than one type of repeat unit, it typically can take the form of a random copolymer. A first polymer 41 and/or a second polymer 81 of an embodiment can be synthesized, for example, by polymerization of radicals, cations, or anions of an unsaturated monomer, corresponding to each structure. In an embodiment, it can be possible to obtain a target resin by using an unsaturated monomer corresponding to a precursor of each structure to perform polymerization, and then performing a polymer reaction.
A first polymer 41 and/or a second polymer 81 in an embodiment of the present disclosure can be synthesized and purified by a suitable method (e.g., radical polymerization). Example synthesis and purification methods that can be suitable are described in paragraphs 0201 to 0202 of Japanese Patent Application Laid-Open No. 2008-292975, for example. The weight average molecular weight of a first polymer 41 and/or a second polymer 81 in an embodiment of the present disclosure can be 7,000 or more as described above, such as in a range of 7,000 to 200,000, in a range of 7,000 to 50,000, in a range of 7,000 to 40,000, or in a range of 7,000 to 30,000, in terms of polystyrene by a Gel Permeation Chromatography (GPC) method, for example. If the weight average molecular weight is less than 7,000, the solubility in an organic developer can become higher, and thus, there can be a concern that a fine pattern can be not formed or not formed according to a given manufacturing specification.
Usually, the polydispersity (molecular weight distribution) of a first polymer 41 and/or a second polymer 81 in an embodiment can be in a range of 1.0 to 3.0, in a range of 1.0 to 2.6, in a range of 1.0 to 2.0, or in a range of 1.4 to 2.0, for example. Generally, the smaller the molecular weight distribution is, the better the resolution and resist shape can be, and the smoother the side wall of the resist pattern can be, and thus roughness can be excellent in an embodiment of the present disclosure.
A photoresist composition can contain a compound capable of generating an acid upon irradiation with actinic rays or radiation (sometimes referred to as a “photoacid generator” or “PAG”). A photoacid generator which can be used may be appropriately selected from a photoinitiator for photocationic polymerization, a photoinitiator for photoradical polymerization, a photo-decoloring agent for coloring matters, a photo-discoloring agent, a known compound used for microresist, or the like, and capable of generating an acid upon irradiation with actinic rays or radiation, and mixtures thereof, for example.
A choice of PAG can be based upon such factors as acidity, catalytic activity, volatility, diffusivity, and solubility. Examples of embodied photoacid generators can include a diazonium salt, a phosphonium salt, a sulfonium salt, an iodonium salt, an imidosulfonate, an oxime sulfonate, a diazodisulfone, a disulfone, or an o-nitrobenzyl sulfonate, for example.
Suitable classes of PAGs generating sulfonic acids can include, but are not limited to, sulfonium or iodonium salts, oximidosulfonates, bissulfonyldiazomethanes, and nitrobenzylsulfonate esters, for example. A PAG can be in non-polymerized or polymeric form, for example, present in a polymerized repeating unit of the polymer matrix. Suitable photoacid generator compounds are disclosed, for example, in U.S. Pat. Nos. 5,558,978, 5,468,589, 6,844,132, 6,855,476, and 6,911,297, which are incorporated herein by reference in their entireties. In some embodiments, a preferred PAG can include one or more of tris(perfluoroalkylsulfonyl)methides, tris(perfluoroalkylsulfonyl)imides, and those generating perfluoroalkylsulfonic acids, for example.
Additional examples of suitable photoacid generators can include, but are not limited to, triphenylsulfonium perfluorooctanesulfonate, triphenylsulfonium perfluorobutanesulfonate, methylphenyldiphenylsulfonium perfluorooctanesulfonate, 4-n-butoxyphenyldiphenylsulfonium perfluorobutanesulfonate, 2,4,6-trimethylphenyldiphenylsulfonium perfluorobutanesulfonate, 2,4,6-trimethylphenyldiphenylsulfonium benzenesulfonate, 2,4,6-trimethylphenyldiphenylsulfonium 2,4,6-triisopropylbenzenesulfonate, phenylthiophenyldiphenylsulfonium 4-dodecylbenzensulfonic acid, tris(-t-butylphenyl)sulfonium perfluorooctanesulfonate, tris(-t-butylphenyl)sulfonium perfluorobutanesulfonate, tris(-t-butylphenyl)sulfonium 2,4,6-triisopropylbenzenesulfonate, tris(-t-butylphenyl)sulfonium benzenesulfonate, and phenylthiophenyldiphenylsulfonium perfluorooctanesulfonate.
Examples of suitable iodonium salts can include, but are not limited to, diphenyl iodonium perfluorobutanesulfonate, bis-(t-butylphenyl)iodonium perfluorobutanesulfonate, bis-(t-butylphenyl)iodonium, perfluorooctanesulfonate, diphenyl iodonium perfluorooctanesulfonate, bis-(t-butylphenyl)iodonium benzenesulfonate, bis-(t-butylphenyl)iodonium 2,4,6-triisopropylbenzenesulfonate, and diphenyliodonium 4-methoxybenzensulfonate.
Examples of tris(perfluoroalkylsulfonyl)methide and tris(perfluoroalkylsulfonyl)imide PAGs can be found in U.S. Pat. Nos. 5,554,664 and 6,306,555, each of which is incorporated herein in its entirety. For an SSA of an embodiment, additional examples of PAGs of this type can be found in Proceedings of SPIE, Vol. 4690, pp. 817-828 (2002).
Suitable methide and imide PAGs can include, but are not limited to, triphenylsulfonium tris(trifluoromethylsulfonyl)methide, methylphenyldiphenylsulfonium tris(perfluoroethylsulfonyl)methide, triphenylsulfonium tris(perfluorobutylsulfonyl)methide, triphenylsulfonium bis(trifluoromethylsulfonyl)imide, triphenylsulfonium bis(perfluoroethylsulfonyl)imide, and triphenylsulfonium bis(perfluorobutylsulfonyl)imide.
Further examples of suitable photoacid generators can be bis(p-toluenesulfonyl)diazomethane, methylsulfonyl p-toluenesulfonyldiazomethane, 1-cyclo-hexylsulfonyl-1-(1,1-dimethylethylsulfonyl)diazomethane, bis(1,1-dimethylethylsulfonyl)diazomethane, bis(1-methylethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, 1-p-toluenesulfonyl-1-cyclohexylcarbonyldiazomethane, 2-methyl-2-(p-toluenesulfonyl)propiophenone, 2-methanesulfonyl-2-methyl-(4-methylthiopropiophenone, 2,4-methyl-2-(p-toluenesulfonyl)pent-3-one, 1-diazo-1-methylsulfonyl-4-phenyl-2-butanone, 2-(cyclohexylcarbonyl-2-(p-toluenesulfonyl)propane, 1-cyclohexylsulfonyl-1cyclohexylcarbonyldiazomethane, 1-diazo-1-cyclohexylsulfonyl-3,3-dimethyl-2-butanone, 1-diazo-1-(1,1-dimethylethylsulfonyl)-3,3-dimethyl-2-butanone, 1-acetyl-1-(1-methylethylsulfonyl)diazomethane, 1-diazo-1-(p-toluenesulfonyl)-3,3-dimethyl-2-butanone, 1-diazo-1-benzenesulfonyl-3,3-dimethyl-2-butanone, 1-diazo-1-(p-toluenesulfonyl)-3-methyl-2-butanone, cyclohexyl 2-diazo-2-(p-toluenesulfonyl)acetate, tert-butyl 2-diazo-2-benzenesulfonylacetate, isopropyl-2-diazo-2-methanesulfonylacetate, cyclohexyl 2-diazo-2-benzenesulfonylacetate, tert-butyl 2 diazo-2-(p-toluenesulfonyl)acetate, 2-nitrobenzyl p-toluenesulfonate, 2,6-dinitrobenzyl p-toluenesulfonate, and 2,4-dinitrobenzyl p-trifluoromethylbenzenesulfonate.
Some more preferred PAGs can be triarylsulfonium perfluoroalkylsulfonates and triarylsulfonium tris(perfluoroalkylsulfonyl)methides. For an SSA of an embodiment, some more preferred PAGs can include triphenylsulfonium perfluorooctanesulfonate (TPS-PFOS), triphenylsulfonium perfluorobutanesulfonate (TPS-Nonaflate), methyiphenyldiphenylsulfonium perfluorooctanesulfonate (TDPS-PFOS), tris(-t-butylphenyl)sulfonium perfluorobutanesulfonate (TTBPS-Nonaflate), triphenylsulfonium tris(trifluoromethylsulfonyl)methide (TPS-C1), or methylphenyldiphenylsulfonium tris(perfluoroethylsulfonyl)methide.
Additional PAG compounds can include, for example: onium salts, for example, triphenylsulfonium trifluoromethanesulfonate, (p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate, tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate, triphenylsulfonium p-toluenesulfonate; di-t-butyphenyliodonium perfluorobutanesulfonate, or di-t-butyphenyliodonium camphorsulfonate.
Non-ionic sulfonates and sulfonyl compounds can function as photoacid generators, for example: nitrobenzyl derivatives, for example, 2-nitrobenzyl-p-toluenesulfonate, 2,6-dinitrobenzyl-p-toluenesulfonate, and 2,4-dinitrobenzyl-p-toluenesulfonate; sulfonic acid esters, for example, 1,2,3-tris(methanesulfonyloxy)benzene, 1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and 1,2,3-tris(p-toluenesulfonyloxy)benzene; diazomethane derivatives, for example, bis(benzenesulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane; glyoxime derivatives, for example, bis-O-(p-toluenesulfonyl)-α-dimethylglyoxime, and bis-O-(n-butanesulfonyl)-α-dimethylglyoxime; sulfonic acid ester derivatives of an N-hydroxyimide compound, for example, N-hydroxysuccinimide methanesulfonic acid ester, N-hydroxysuccinimide trifluoromethanesulfonic acid ester; or halogen-containing triazine compounds, for example, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, and 2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine.
Suitable non-polymerized photoacid generators that can be used are further described in U.S. Pat. No. 8,431,325 to Hashimoto et al. in column 37, lines 11-47 and columns 41-91. For an SSA of an embodiment, other suitable sulfonate PAGs can include sulfonated esters and sulfonyloxy ketones, nitrobenzyl esters, s-triazine derivatives, benzoin tosylate, t-butylphenyl α-(p-toluenesulfonyloxy)-acetate, and t-butyl α-(p-toluenesulfonyloxy)-acetate; as described in U.S. Pat. Nos. 4,189,323 and 8,431,325. PAGs that are onium salts typically can include an anion having a sulfonate group or a non-sulfonate type group, such as a sulfonamidate group, a sulfonimidate group, a methide group, or a borate group.
A photoresist composition may optionally include a plurality of PAGs. The plural PAGs can be polymeric, non-polymeric, or can include both polymeric and non-polymeric PAGs. In some embodiments, each of the plurality of PAGs can be non-polymeric. In some embodiments, when a plurality of PAGs are used, a first PAG can include a sulfonate group on the anion and a second PAG can include an anion that is free of sulfonate groups, such anion containing for example, a sulfonamidate group, a sulfonimidate group, a methide group, or a borate group, such as described above, for example.
In some embodiments, the PAG can be a polymeric PAG, wherein the compound capable of generating an acid upon irradiation with actinic rays or radiation is introduced into the main or side chain of the polymer. For an SSA of an embodiment, examples can include, for example, compounds described in U.S. Pat. No. 3,849,137, German Patent 3,914,407, JP-A-63-26653, JP-A-55-164824, JP-A-62-69263, JP-A-63-146038, JP-A-63-163452, JP-A-62-153853, and JP-A-63-146029.
In some embodiments, a photoresist composition can include a non-polymerized photoacid generator in an amount from about 1 to 65 wt %, from about 5 to 55 wt %, or from about 8 to 30 wt %, based on total solids of the photoresist composition, for example. In some embodiments, a photoresist composition can include two or more different non-polymerized photoacid generators in a combined amount from about 1 to 65 wt %, from about 5 to 55 wt %, or from about 8 to 30 wt %, based on total solids of the photoresist composition, for example. In some embodiments, a photoacid generator mixture can include two or three photoacid generators. Such mixtures can be of a same class or different classes. Examples of some preferred mixtures can include sulfonium salts with bis-sulfonyldiazomethane compounds, sulfonium salts and imidosulfonates, and two sulfonium salts, for example.
Before deposition and/or at the time of deposition, a photoresist composition in an embodiment of the present disclosure can further include a solvent for dissolving the components of the composition and facilitating its coating on a substrate, and most of or all of the solvent can be evaporated during the deposition operation, for example. Preferably, the solvent can be an organic solvent conventionally used in the manufacture of electronic devices. Suitable solvents can include, for example: aliphatic hydrocarbons such as hexane and heptane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane and 1-chlorohexane; alcohols such as methanol, ethanol, 1-propanol, iso-propanol, tert-butanol, 2-methyl-2-butanol and 4-methyl-2-pentanol; propylene glycol monomethyl ether (PGME), ethers such as diethyl ether, tetrahydrofuran, 1,4-dioxane and anisole; ketones such as acetone, methyl ethyl ketone, methyl iso-butyl ketone, 2-heptanone and cyclohexanone (CHO); esters such as ethyl acetate, n-butyl acetate, propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate (EL), hydroxyisobutyrate methyl ester (HBM) and ethyl acetoacetate; lactones such as gamma-butyrolactone (GBL) and epsilon-caprolactone; lactams such as N-methyl pyrrolidone; nitriles such as acetonitrile and propionitrile; cyclic or non-cyclic carbonate esters such as propylene carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate, diphenyl carbonate, and propylene carbonate; polar aprotic solvents such as dimethyl sulfoxide and dimethyl formamide; water; or any combination thereof. Of these, preferred solvents can be PGME, PGMEA, EL, GBL, HBM, CHO, or any combination thereof. The total solvent content (i.e., cumulative solvent content for all solvents) in the photoresist compositions is typically from 40 to 99 wt %, more typically from 70 to 99 wt %, and still more typically from 85 to 99 wt %, based on total weight of the photoresist composition, for example. The desired solvent content can depend, for example, on the desired thickness of the coated photoresist layer and coating conditions.
In some embodiments, a quencher base or base generator can be included in the first intermediate structure 11 to help control diffusion of an active material in/of the SSA 15. For an embodiment, suitable quencher base or base generators can include, but are not limited to, hydroxides, carboxylates, amines, imines, amides, or mixtures thereof. Specific examples of bases can include ammonium carbonate, ammonium hydroxide, ammonium hydrogen phosphate, ammonium phosphate, tetramethylammonium carbonate, tetramethylammonium hydroxide, tetramethylammonium hydrogen phosphate, tetramethylammonium phosphate, tetraethylammonium carbonate, tetraethylammonium hydroxide, tetraethylammonium hydrogen phosphate, tetraethylammonium phosphate, or combinations thereof. Amines can include aliphatic amines, cycloaliphatic amines, aromatic amines, or heterocyclic amines. The amine can be a primary, secondary, or tertiary amine. The amine can be a monoamine, diamine, or polyamine. Suitable amines can include Cl-30 organic amines, imines, or amides, or may be a Cl-30 quaternary ammonium salt of a strong base (e.g., a hydroxide or alkoxide) or a weak base (e.g., a carboxylate). In some embodiments, example bases can include amines such as tripropylamine, dodecylamine, tris(2-hydroxypropyl)amine, tetrakis(2-hydroxypropyl)ethylenediamine; aryl amines such as diphenylamine, triphenylamine, aminophenol, and 2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, Troger's base, a hindered amine such as diazabicycloundecene (DBU) or diazabicyclononene (DBN), amides like tert-butyl l,3-dihydroxy-2-(hydroxymethyl)propan-2-ylcarbamate and tert-butyl 4-hydroxypiperidine-l-carboxylateor; or ionic quenchers including quaternary alkyl ammonium salts such as tetrabutylammonium hydroxide (TBAH) or tetrabutylammonium lactate.
In some embodiments, the amine can be a hydroxyamine. Examples of hydroxyamines can include hydroxyamines having one or more hydroxyalkyl groups each having 1 to about 8 carbon atoms, and sometimes preferably 1 to about 5 carbon atoms such as hydroxymethyl, hydroxyethyl and hydroxybutyl groups. Specific examples of hydroxy amines can include mono-, di- and tri-ethanolamine, 3-amino-1-propanol, 2-amino-2-methyl-1-propanol, 2-amino-2-ethyl-1,3-propanediol, tris(hydroxymethyl)aminomethane, N-methylethanolamine, 2-diethylamino-2-methyl-1-propanol, and triethanolamine.
In an embodiment, suitable base generators can be thermal base generators. A thermal base generator (TAG) can form a base upon heating above a first temperature, typically about 140° C. or higher. The thermal base generator can include a functional group such as an amide, sulfonamide, imide, imine, O-acyl oxime, benzoyloxycarbonyl derivative, quarternary ammonium salt, nifedipine, carbamate, or combinations thereof, for example.
In an embodiment, example thermal base generators can include:
A quencher base or base generator can be in non-polymeric or polymer-bound form. When in polymeric form, a quencher can be present in polymerized units on the polymer. The polymerized units containing the quencher can be typically present in an amount of from 0.1 to 30 mole %, preferably from 1 to 10 mole %, and more preferably from 1 to 2 mole %, based on total repeating units of the polymer.
In an embodiment, the photoresist compositions described above may further include one or more additional, optional additives. For example, optional additives may include actinic and contrast dyes, anti-striation agents, plasticizers, speed enhancers, sensitizers, photo-decomposable quenchers (also known as photo-decomposable bases), basic quenchers, surfactants, and the like, or combinations thereof. If present, the optional additives can be typically present in the photoresist compositions in an amount from 0.01 to 10 wt %, based on total solids of the photoresist composition.
Photo-decomposable quenchers can generate a weak acid upon irradiation. The acid generated from a photo-decomposable quencher can be not strong enough to react rapidly with acid-labile groups that are present in the resist matrix. Example photo-decomposable quenchers can include, for example, photo-decomposable cations, and can be preferably those also useful for preparing strong acid generator compounds, paired with an anion of a weak acid (pKa>−1) such as, for example, an anion of a C1-20 carboxylic acid or C1-20 sulfonic acid.
Example carboxylic acids can include formic acid, acetic acid, propionic acid, tartaric acid, succinic acid, cyclohexanecarboxylic acid, benzoic acid, salicylic acid, and the like. Example sulfonic acids can include p-toluene sulfonic acid, camphor sulfonic acid and the like. In some embodiments, the photo-decomposable quencher can be a photo-decomposable organic zwitterion compound such as diphenyliodonium-2-carboxylate.
The photo-decomposable quencher can be in non-polymeric or polymer-bound form. When in polymeric form, the photo-decomposable quencher can be present in polymerized units on the first polymer or second polymer. The polymerized units containing the photo-decomposable quencher can be typically present in an amount from 0.1 to 30 mole %, sometimes preferably from 1 to 10 mole %, and sometimes more preferably from 1 to 2 mole %, based on total repeating units of the polymer.
Example basic quenchers can include, for example: linear aliphatic amines such as tributylamine, trioctylamine, triisopropanolamine, tetrakis(2-hydroxypropyl)ethylenediamine:n-tert-butyldiethanolamine, tris(2-acetoxy-ethyl) amine, 2,2′,2″,2′″-(ethane-1,2-diylbis(azanetriyl))tetraethanol, 2-(dibutylamino)ethanol, and 2,2′,2″-nitrilotriethanol; cyclic aliphatic amines such as 1-(tert-butoxycarbonyl)-4-hydroxypiperidine, tert-butyl 1-pyrrolidinecarboxylate, tert-butyl 2-ethyl-1H-imidazole-1-carboxylate, di-tert-butyl piperazine-1,4-dicarboxylate, and N-(2-acetoxy-ethyl)morpholine; aromatic amines such as pyridine, di-tert-butyl pyridine, and pyridinium; linear and cyclic amides and derivatives thereof such as N,N-bis(2-hydroxyethyl)pivalamide, N,N-diethylacetamide, N1,N1,N3,N3-tetrabutylmalonamide, 1-methylazepan-2-one, 1-allylazepan-2-one, and tert-butyl 1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylcarbamate; ammonium salts such as quaternary ammonium salts of sulfonates, sulfamates, carboxylates, and phosphonates; imines such as primary and secondary aldimines and ketimines; diazines such as optionally substituted pyrazine, piperazine, and phenazine; diazoles such as optionally substituted pyrazole, thiadiazole, and imidazole; or optionally substituted pyrrolidones such as 2-pyrrolidone and cyclohexyl pyrrolidine.
The basic quenchers can be in non-polymeric or polymer-bound form. When in polymeric form, the quencher can be present in polymerized units on the polymer. The polymerized units containing the quencher can be typically present in an amount of from 0.1 to 30 mole %, sometimes preferably from 1 to 10 mole %, and sometimes more preferably from 1 to 2 mole %, based on total repeating units of the polymer.
Example surfactants can include fluorinated and non-fluorinated surfactants and can be ionic or non-ionic, with non-ionic surfactants being sometimes preferable. Example fluorinated non-ionic surfactants can include perfluoro C4 surfactants such as FC-4430 and FC-4432 surfactants, available from 3M Corporation; and fluorodiols such as POLYFOX PF-636, PF-6320, PF-656, and PF-6520 fluorosurfactants from Omnova. In some embodiments, the photoresist composition can further include a surfactant polymer including a fluorine-containing repeating unit.
In an embodiment of present disclosure, an overcoat resist composition may be used to form an overcoat resist layer 21. The overcoat resist composition can include a second polymer 81, a solubility shifting agent, a solvent, and may also contain additional, optional components.
Next, some example materials that can be implemented and used for an SSA 15 (solubility shifting agent) referenced above while describing the example embodiments of
An SSA of an embodiment of the present disclosure can include a thermal-acid generator (TAG) that is configured to generate an acid in response to heat and/or a photo-acid generator (PAG) that is configured to generate an acid in response to actinic radiation, for example. In an embodiment, the SSA can include an acid or an acid generator such as a free acid, TAG or PAG, for example.
In an embodiment, an SSA can include multiple solubility shifting agents combined, such as multiple PAGs, multiple TAGs, or one or more PAGs combined with one or more TAGs, or any combination thereof with an already free acid, for example.
In some embodiments, an SSA can be an acid that is an organic acid, which can include both non-aromatic acids and aromatic acids optionally having fluorine substitution. Suitable organic acids for an SSA of an embodiment can include: carboxylic acids and polycarboxylic acids such as alkanoic acids, including formic acid, acetic acid, propionic acid, butyric acid, dichloroacetic acid, trichloroacetic acid, perfluoroacetic acid, perfluorooctanoic acid, oxalic acid malonic acid and succinic acid; hydroxyalkanoic acids, such as citric acid; aromatic carboxylic acids such as benzoic acid, fluorobenzoic acid, hydroxybenzoic acid, and naphthoic acid; organic phosphorus acids such as dimethylphosphoric acid and dimethylphosphinic acid; and sulfonic acids such as optionally fluorinated alkylsulfonic acids including methanesulfonic acid, trifluoromethanesulfonic acid, ethanesulfonic acid, 1-butanesulfonic acid, 1-perfluorobutanesulfonic acid, 1,1,2,2-tetrafluorobutane-1-sulfonic acid, 1,1,2,2-tetrafluoro-4-hydroxybutane-1-sulfonic acid, 1-pentanesulfonic acid, 1-hexanesulfonic acid, and 1-heptanesulfonic acid; or any combination thereof, for example.
In some embodiments, an SSA can be an aromatic sulfonic acid. For example, an aromatic sulfonic acid can be of general Formula 4:
In Formula 4, Ar1 can represent an aromatic group, which can be carbocyclic, heterocyclic, or a combination thereof. The aromatic group can be monocyclic, for example, phenyl or pyridyl, or polycyclic, for example biphenyl, and can include: plural fused aromatic rings such as naphthyl, anthracenyl, pyrenyl, or quinolinyl; or fused ring systems having both aromatic and non-aromatic rings such as 1,2,3,4-tetrahydronaphthalene, 9,10-dihydroanthracene or fluorene. A wide variety of aromatic groups may be used for Ar1. The aromatic group typically can have from 5 to 40 carbons, preferably from 6 to 35 carbons, and more preferably from 6 to 30 carbons. Suitable aromatic groups can include, but are not limited to: phenyl, biphenyl, naphthalenyl, anthracenyl, phenanthrenyl, pyrenyl, tetracenyl, triphenylenyl, tetraphenyl, benzo[f]tetraphenyl, benzo[m]tetraphenyl, benzo[k]tetraphenyl, pentacenyl, perylenyl, benzo[a]pyrenyl, benzo[e]pyrenyl, benzo[ghi]perylenyl, coronenyl, quinolonyl, 7,8-benzoquinolinyl, fluorenyl, and 12H-dibenzo[b,h]fluorenyl. Of these, phenyl can be particularly preferred.
In Formula 4, R1 independently can represent a halogen atom, hydroxy, substituted or unsubstituted alkyl, substituted or unsubstituted heteroalkyl, substituted or unsubstituted carbocyclic aryl, substituted or unsubstituted heterocyclic aryl, substituted or unsubstituted alkoxy, or a combination thereof. R1 can also include one or more groups such as ester, carboxy, ether, or a combination thereof.
In Formula 4, “a” can represent an integer of 0 or more and “b” can represent an integer of 1 or more, provided that a+b is not greater than the total number of available aromatic carbon atoms of Ar1. Preferably, two or more of R1 can be independently a fluorine atom or a fluoroalkyl group bonded directly to an aromatic ring carbon atom.
The aromatic acid can be a sulfonic acid including a phenyl, biphenyl, naphthyl, anthracenyl, thiophene or furan group. The aromatic acid can be chosen from one or more aromatic sulfonic acids of the following general Formulas 5-10:
In Formula 5, R1 can independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C20 aryl group, or a combination thereof, optionally containing one or more group chosen from carbonyl, carbonyloxy, sulfonamido, ether, thioether, a substituted or unsubstituted alkylene group, or a combination thereof.
In Formula 5, Z1 can independently represent a group chosen from carboxyl, hydroxy, nitro, cyano, C1 to C5 alkoxy, formyl and sulfonic acid. In Formula 5, “a” and “b” can be independently an integer from 0 to 5, and a+b can be 5 or less.
In Formula 6, R2 and R3 each can independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C16 aryl group, or a combination thereof, optionally containing one or more group chosen from carbonyl, carbonyloxy, sulfonamido, ether, thioether, a substituted or unsubstituted alkylene group, or a combination thereof.
In Formula 6, Z2 and Z3 each can independently represent a group chosen from carboxyl, hydroxy, nitro, cyano, C1 to C5 alkoxy, formyl and sulfonic acid. In Formula 6, “c” and “d” can be independently an integer from 0 to 4, c+d can be 4 or less, “e” and “f” can be independently an integer from 0 to 3, and e+f can be 3 or less.
In Formula 7, R4, R5 and R6 each can independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C12 aryl group, or a combination thereof, optionally containing one or more group chosen from carbonyl, carbonyloxy, sulfonamido, ether, thioether, a substituted or unsubstituted alkylene group, or a combination thereof
In Formula 7, Z4, Z5 and Z6 each can independently represent a group chosen from carboxyl, hydroxy, nitro, cyano, C1 to C5 alkoxy, formyl and sulfonic acid. In Formula 7, “g” and “h” can be independently an integer from 0 to 4, g+h can be 4 or less, “i” and “j” can be independently an integer from 0 to 2, i+j can be 2 or less, “k” and “1” can be independently an integer from 0 to 3, and k+l can be 3 or less.
In Formula 8, R4, R5 and R6 each can independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C12 aryl group, or a combination thereof, optionally containing one or more group chosen from carbonyl, carbonyloxy, sulfonamido, ether, thioether, a substituted or unsubstituted alkylene group, or a combination thereof.
In Formula 8, Z4, Z5 and Z6 each can independently represent a group chosen from carboxyl, hydroxy, nitro, cyano, C1 to C5 alkoxy, formyl and sulfonic acid. In Formula 8, “g” and “h” can be independently an integer from 0 to 4, g+h can be 4 or less, “i” and “j” can be independently an integer from 0 to 1, i+j can be 1 or less, “k” and “1” can be independently an integer from 0 to 4, and k+l can be 4 or less.
In Formula 9, R7 and R8 each can independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C14 aryl group, or a combination thereof, optionally containing one or more group chosen from carboxyl, carbonyl, carbonyloxy, sulfonamido, ether, thioether, a substituted or unsubstituted alkylene group, or a combination thereof
In Formula 9, Z7 and Z8 each can independently represent a group chosen from hydroxy, nitro, cyano, C1 to C5 alkoxy, formyl and sulfonic acid. In Formula 9, “m” and “n” can be independently an integer from 0 to 5, m+n can be 5 or less, “o” and “p” can be independently an integer from 0 to 4, and o+p can be 4 or less.
In Formula 10, X can be O or S. In Formula 10, R9 can independently represent a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C20 aryl group, or a combination thereof, optionally containing one or more group chosen from carbonyl, carbonyloxy, sulfonamido, ether, thioether, a substituted or unsubstituted alkylene group, or a combination thereof.
In Formula 10, Z9 can independently represent a group chosen from carboxyl, hydroxy, nitro, cyano, C1 to C5 alkoxy, formyl and sulfonic acid. In Formula 10, “q” and “r” can be independently an integer from 0 to 3, and q+r can be 3 or less.
For each of the structures of Formulas 5-10, the R1-R9 groups can optionally form a fused structure together with their respective associated rings, for example.
For an SSA of an embodiment, example aromatic sulfonic acids can include, without limitation, the following:
For an SSA of an embodiment, example non-aromatic sulfonic acids can include, without limitation, the following:
For an SSA of an embodiment, suitable thermal acid generators can include those capable of generating the acids described above. The thermal acid generator (TAG) can be non-ionic or ionic.
For an SSA of an embodiment, suitable nonionic thermal acid generators can include, for example, cyclohexyl trifluoromethyl sulfonate, methyl trifluoromethyl sulfonate, cyclohexyl p-toluenesulfonate, methyl p-toluenesulfonate, cyclohexyl 2,4,6-triisopropylbenzene sulfonate, nitrobenzyl esters, benzoin tosylate, 2-nitrobenzyl tosylate, tris(2,3-dibromopropyl)-l, 3, 5-triazine-2, 4, 6-trione, alkyl esters of organic sulfonic acids, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, oxalic acid, phthalic acid, phosphoric acid, camphorsulfonic acid, 2,4,6-trimethylbenzene sulfonic acid, triisopropylnaphthalene sulfonic acid, 5-nitro-0-toluene sulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzene sulfonic acid, 2-nitrobenzene sulfonic acid, 3-chlorobenzene sulfonic acid, 3-bromobenzene sulfonic acid, 2-fluorocaprylnaphthalene sulfonic acid, dodecylbenzene sulfonic acid, 1-naphthol-5-sulfonic acid, 2-methoxy-4-hydroxy-5-benzoyl-benzene sulfonic acid, or their salts, or combinations thereof.
For an SSA of an embodiment, suitable ionic thermal acid generators can include, for example, dodecylbenzenesulfonic acid triethylamine salts, dodecylbenzenedisulfonic acid triethylamine salts, p-toluene sulfonic acid-ammonium salts, p-toluene sulfonic acid-pyridinium salts, sulfonate salts, such as carbocyclic aryl and heteroaryl sulfonate salts, aliphatic sulfonate salts, or benzenesulfonate salts, or combinations thereof. Compounds that can generate a sulfonic acid upon activation can be generally suitable as a TAG for an SSA of an embodiment, for example. For an SSA of an embodiment, some preferred thermal acid generators can include p-toluenesulfonic acid ammonium salts and heteroaryl sulfonate salts, for example.
For example, for an SSA of an embodiment, the TAG can be preferably ionic with a reaction scheme for generation of a sulfonic acid as shown below:
(BH)+ Formula 11
Formula 11 can be the monoprotonated form of a nitrogen-containing base B. In Formula 11, suitable nitrogen-containing bases B can include, for example: optionally substituted amines such as ammonia, difluoromethylammonia, C1-20 alkyl amines, and C3-30 aryl amines, for example, nitrogen-containing heteroaromatic bases such as pyridine or substituted pyridine (e.g., 3-fluoropyridine), pyrimidine and pyrazine; and nitrogen-containing heterocyclic groups, for example, oxazole, oxazoline, or thiazoline. The foregoing nitrogen-containing bases B can be optionally substituted, for example, with one or more group chosen from alkyl, aryl, halogen atom (preferably fluorine), cyano, nitro and alkoxy. Of these, base B can be preferably a heteroaromatic base.
Base B typically can have a pKa from 0 to 5.0, or between 0 and 4.0, or between 0 and 3.0, or between 1.0 and 3.0. As used herein, the term “pKa” is used in accordance with its art-recognized meaning, that is, pKa can be the negative log (to the base 10) of the dissociation constant of the conjugate acid (BH)+ of the basic moiety (B) in aqueous solution at about room temperature. In certain embodiments, base B can have a boiling point less than about 170° C., or less than about 160° C., 150° C., 140° C., 130° C., 120° C., 110° C., 100° C., or 90° C.
For an SSA of an embodiment, example suitable nitrogen-containing cations (BH)+ can include NH4+, CF2HNH2+, CF3CH2NH3+, (CH3)3NH+, (C2H5)3NH+, (CH3)2(C2H5)NH+ and the following in which Y is alkyl, preferably, methyl or ethyl:
Other suitable cations can include onium cations. Suitable onium cations can include, for example, sulfonium and iodonium cations, for example, those of the following general Formula 12:
+X—(R10)s Formula 12
In Formula 12, X can be S or I, wherein when X is I then “a” can be 2, and when X is S then “a” can be 3. In Formula 12, R10 can be independently chosen from organic groups such as optionally substituted C1-30 alkyl, polycyclic or monocyclic C3-30 cycloalkyl, polycyclic or monocyclic C6-30 aryl, or a combination thereof, wherein when X is S, two of the R groups together optionally form a ring.
For an SSA of an embodiment, example suitable sulfonium and iodonium cations include the following:
For an SSA of an embodiment, suitable photoacid generators can include those described above in the photoresist description.
In an embodiment of the present disclosure, the overcoat resist composition contains an organic solvent that can include an organic solvent conventionally used in the manufacture of electronic devices.
For an embodiment, a solvent can be any suitable solvent provided that it does not dissolve a first intermediate structure 11 intended to remain (e.g., for an anti-spacer pattern). For an embodiment, a solvent can be typically chosen from water, organic solvents, and mixtures thereof. In some embodiments, a solvent can include an organic-based solvent system including one or more organic solvents. The term “organic-based” can indicate that the solvent system includes greater than 50 wt % organic solvent based on total solvents of a given composition, more typically greater than 90 wt %, greater than 95 wt %, greater than 99 wt % or 100 wt % organic solvents, based on total solvents of the compositions. In an embodiment, a solvent component can be typically present in an amount of from 90 to 99 wt % based on the composition.
In an embodiment, suitable organic solvents can include, for example: alkyl esters such as alkyl propionates such as n-butyl propionate, n-pentyl propionate, n-hexyl propionate and n-heptyl propionate, and alkyl butyrates such as n-butyl butyrate, isobutyl butyrate and isobutyl isobutyrate; ketones such as 2,5-dimethyl-4-hexanone and 2,6-dimethyl-4-heptanone; aliphatic hydrocarbons such as n-heptane, n-nonane, n-octane, n-decane, 2-methylheptane, 3-methylheptane, 3,3-dimethylhexane and 2,3,4-trimethylpentane, and fluorinated aliphatic hydrocarbons such as perfluoroheptane; alcohols such as straight, branched or cyclic C4-C9 monohydric alcohol such as 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 3-methyl-1-butanol, 1-pentanol, 2-pentanol, 4-methyl-2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol and 4-octanol; 2,2,3,3,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-l-pentanol and 2,2,3,3,4,4,5,5,6,6-decafluoro-1-hexanol, and C5-C9 fluorinated diols such as 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol and 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol; ethers such as isopentyl ether and dipropylene glycol monomethyl ether; or mixtures containing one or more of these solvents, for example.
In an embodiment, a solvent included in a developer may depend on a composition and tone of a first intermediate structure 11. When a first intermediate structure 11 is formed from a (meth)acrylate polymer, as is typical for ArF resists, and the resist can be developed as a PTD resist, and the solvent system can include one or more polar organic solvents. For example, a polar solvent can include methyl isobutyl carbinol (MIBC). A developer containing an organic solvent can also include aliphatic hydrocarbons, esters, and ethers as cosolvents such as, for example, decane, isobutyl isobutyrate, isoamyl ether, and combinations thereof. In some embodiments, an organic solvent can include MIBC and a cosolvent. In such embodiments, the MIBC can be included in the solvent in an amount ranging from 60 to 99%, based on the total volume of solvent. Accordingly, the cosolvent can be included in amount ranging from 1 to 40%, based on the total volume of solvent.
When a first intermediate structure 11 is formed from a vinyl aromatic-based polymer, as is typical for KrF and EUV photoresists, and the resist can be developed as a PTD resist, and developer can contain a solvent system including one or more nonpolar organic solvents. The term “nonpolar organic-based” can indicate that the solvent system includes greater than 50 wt % of combined nonpolar organic solvents based on total solvents of the composition, more typically greater than 70 wt %, greater than 85 wt % or 100 wt %, combined nonpolar organic solvents, based on total solvents of the composition. The nonpolar organic solvents can be typically present in the solvent system in a combined amount of from 70 to 98 wt %, preferably 80 to 95 wt %, more preferably from 85 to 98 wt %, based on the solvent system, for example.
In an embodiment, suitable nonpolar solvents can include, for example, ethers, hydrocarbons, and combinations thereof, with ethers being sometimes preferred. In an embodiment, suitable ether solvents can include, for example, alkyl monoethers and aromatic monoethers, particularly preferred of which can be those having a total carbon number of from 6 to 16. In an embodiment, suitable alkyl monoethers can include, for example, 1,4-cineole, 1,8-cineole, pinene oxide, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, di-n-pentyl ether, diisoamyl ether, dihexyl ether, diheptyl ether, and dioctyl ether, with diisoamyl ether being preferred. In an embodiment, suitable aromatic monoethers can include, for example, anisole, ethylbenzyl ether, diphenyl ether, dibenzyl ether and phenetole, with anisole being preferred. In an embodiment, suitable aliphatic hydrocarbons can include, for example, n-heptane, 2-methylheptane, 3-methylheptane, 3, 3-dimethylhexane, 2,3,4-trimethylpentane, n-octane, n-nonane, n-decane, and fluorinated compounds such as perfluoroheptane. In an embodiment, suitable aromatic hydrocarbons can include, for example, benzene, toluene, and xylene.
In some embodiments, the solvent system can further include one or more alcohol and/or ester solvents. For certain compositions, an alcohol and/or ester solvent can provide enhanced solubility with respect to the solid components of the composition. In an embodiment, suitable alcohol solvents can include, for example: straight, branched or cyclic C4-9 monohydric alcohol such as 1-butanol, 2-butanol, isobutyl alcohol, tert-butyl alcohol, 3-methyl-1-butanol, 1-pentanol, 2-pentanol, 4-methyl-2-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, 2,2,3,3,4,4-hexafluoro-1-butanol, 2,2,3,3,4,4,5,5-octafluoro-l-pentanol, and 2,2,3,3,4,4,5,5,6,6-decafluoro-1-hexanol; and C5-9 fluorinated diols such as 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, 2,2,3,3,4,4,5,5-octafluoro-1,6-hexanediol, or 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro-1,8-octanediol. In an embodiment, an alcohol solvent can be preferably a C4-9 monohydric alcohol, with 4-methyl-2-pentanol being preferred. In an embodiment, suitable ester solvents can include, for example, alkyl esters having a total carbon number of from 4 to 10, for example, alkyl propionates such as n-butyl propionate, n-pentyl propionate, n-hexyl propionate, and n-heptyl propionate, and alkyl butyrates such as n-butyl butyrate, isobutyl butyrate, and isobutyl isobutyrate. The one or more alcohol and/or ester solvents if used in a solvent system of an embodiment, can be typically present in a combined amount of from 2 to 50 wt %, more typically in an amount of from 2 to 30 wt %, based on the solvent system, for example.
In an embodiment, a solvent system can also include one or more additional solvents chosen, for example, from one or more of: ketones such as 2,5-dimethyl-4-hexanone and 2,6-dimethyl-4-heptanone; and polyethers such as dipropylene glycol monomethyl ether and tripropylene glycol monomethyl ether. Such additional solvents, if used, can be typically present in a combined amount of from 1 to 20 wt % based on the solvent system.
In an embodiment, when a first intermediate structure 11 is formed from a vinyl aromatic-based polymer, a particularly preferred organic-based solvent system can include one or more monoether solvents in a combined amount of from 70 to 98 wt % based on the solvent system, and one or more alcohol and/or ester solvents in a combined amount of from 2 to 30 wt % based on the solvent system. The solvent system can be typically present in a developer in an amount of from 90 to 99 wt %, preferably from 95 to 99 wt %, based on the developer composition, for example. In an embodiment in which a first intermediate structure 11 is a NTD resist, a suitable organic solvent can include, but is not limit to, n-butyl acetate, 2-heptanone, propylene glycol methyl ether, propylene glycol methyl ether acetate, and combinations thereof, for example.
In an embodiment of present disclosure, the overcoat resist composition may include optional components selected from the list of quenchers and optional components described above.
More example embodiments of the present disclosure are summarized here. Other embodiments can also be understood from the entirety of the specification as well as the claims filed herein.
Example 1. A method for forming a patterned mask, the method including: providing a patterned resist layer on a substrate, where the patterned resist layer includes a first material including a first polymer; depositing an overcoat resist layer over the patterned resist layer, where the overcoat resist layer includes a second material including a second polymer and a solubility shifting agent; and diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned resist layer and chemically transforming the exterior regions of the patterned resist layer to anti-spacer regions of a third material to a first depth into the patterned resist layer.
Example 2. The method of example 1, further including: removing the exterior regions using a developer to form an anti-spacer pattern including remaining portions of the patterned resist layer and the overcoat resist layer having openings to the substrate corresponding to the exterior regions, where at least part of the openings has a critical dimension corresponding to the first depth.
Example 3. The method of one of examples 1 and 2, where the second polymer includes a functional group protected by a protecting group, where the overcoat resist layer includes an overburden region overlying the patterned resist layer, where the third material is soluble in a developer, and where the method further includes: activating the solubility shifting agent to deprotect the functional group of the second polymer and chemically transforming at least the overburden region of the overcoat resist layer to a fourth material that has a non-zero dissolution rate in the developer that is slower than a dissolution rate of the third material in the developer.
Example 4. The method of example 3, where activating the solubility shifting agent includes exposing at least the overburden region with actinic radiation.
Example 5. The method of example 4, where exposing at least the overburden region includes a flood exposure of the substrate with the actinic radiation.
Example 6. The method of one of examples 1 to 5, where diffusing at least the catalyst portion includes baking the substrate to diffuse at least the catalyst portion of the solubility shifting agent.
Example 7. The method of example 6, further including: exposing the substrate to a flood of actinic radiation to generate the catalyst portion of the solubility shifting agent in the overcoat resist layer before diffusing at least the catalyst portion from the overcoat resist layer into the exterior regions of the patterned resist layer.
Example 8. A method for forming a patterned mask, the method including: providing a patterned resist layer on a substrate, where the patterned resist layer includes a first material including a first polymer, where the first material is soluble in a first solvent system, where the first material is insoluble in a developer containing a polar solvent; depositing an overcoat resist layer over the patterned resist layer, where the overcoat resist layer includes a second material including a solubility shifting agent and a second polymer with a functional group protected by a protecting group, where the overcoat resist layer includes an overburden region overlying the patterned resist layer, where the second material is soluble in a second solvent system that is less polar than the first solvent system, and where the second material is insoluble in the developer containing the polar solvent; activating the solubility shifting agent to deprotect the functional group of the second polymer and chemically transforming at least the overburden region of the overcoat resist layer to a third material that has a non-zero dissolution rate in the developer containing the polar solvent; and diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned resist layer and chemically transforming the exterior regions of the patterned resist layer to anti-spacer regions of a fourth material to a first depth into the patterned resist layer, where the fourth material is soluble in the developer containing the polar solvent, the fourth material having a dissolution rate in the developer that is faster than the non-zero dissolution rate of the third material in the developer.
Example 9. The method of example 8, further including: removing the exterior regions and the overburden region using a developer to form an anti-spacer pattern including remaining portions of the patterned resist layer and the overcoat resist layer having openings to the substrate corresponding to the exterior regions, where at least part of the openings has a critical dimension corresponding to the first depth.
Example 10. The method of one of examples 8 and 9, where the patterned resist layer is a patterned extreme ultraviolet (EUV) photoresist layer.
Example 11. The method of one of examples 8 to 10, where the developer is an aqueous base.
Example 12. The method of example 11, where the developer is a tetramethylammonium hydroxide (TMAH) developer.
Example 13. The method of one of examples 8 to 12, where the protecting group is a vinyl ether protecting group.
Example 14. The method of one of examples 8 to 13, where the functional group is a hydroxyl group.
Example 15. The method of one of examples 8 to 14, where the second polymer includes styrene, para-hydroxystyrene, an acrylate, a methacrylate, norbornene, or any combination thereof.
Example 16. The method of example 15, where the second polymer includes para-hydroxystyrene.
Example 17. The method of example 16, where the second polymer further includes styrene and n-butyl acrylate, tert-butyl acrylate or combinations thereof.
Example 18. A method for forming a patterned mask, the method including: providing a patterned photoresist layer on a substrate, where the patterned photoresist layer includes a first material including a first polymer; depositing an overcoat resist layer over the patterned photoresist layer, where the overcoat resist layer includes a second material including a second polymer and a solubility shifting agent; diffusing at least a catalyst portion of the solubility shifting agent from the overcoat resist layer into exterior regions of the patterned photoresist layer and chemically transforming the exterior regions of the patterned photoresist layer to anti-spacer regions of a third material to a first depth into the patterned photoresist layer; and removing the anti-spacer regions using a developer to form an anti-spacer pattern including remaining portions of the patterned photoresist layer and the overcoat resist layer having openings to the substrate corresponding to the anti-spacer regions, where at least part of the openings has a critical dimension corresponding to the first depth.
Example 19. The method of example 18, where the patterned photoresist layer is an extreme ultraviolet (EUV) photoresist layer, where the developer contains a polar solvent, where the second polymer includes a functional group protected by a protecting group, where the overcoat resist layer includes an overburden region overlying the patterned resist layer, and where the method further includes: activating the solubility shifting agent to deprotect the functional group of the second polymer and chemically transforming at least the overburden region of the overcoat resist layer to a fourth material that has a non-zero dissolution rate in the developer that is slower than a dissolution rate of the third material in the developer.
Example 20. The method of example 19, where the second polymer includes para-hydroxystyrene, styrene, and an alkyl acrylate, where the protecting group is a vinyl ether protecting group including an isobutyl group, a 2-ethylheptyl group, or a combination thereof, where the developer is a tetramethylammonium hydroxide (TMAH) developer.
Example 21. The method of one of examples 19 and 20, where the alkyl acrylate is n-butyl acrylate, tert-butyl acrylate or combinations thereof.
While illustrative and example embodiments have been described with reference to illustrative drawings, this description is not intended to be construed in a necessarily limiting sense. Various modifications and combinations of the illustrative and example embodiments, as well as other embodiments, can be apparent to persons skilled in the pertinent art upon referencing the present disclosure. It is therefore intended that the appended claims encompass any and all of such modifications, equivalents, or embodiments.
This application claims the priority and benefit of U.S. Provisional Application No. 63/616,080, filed on Dec. 29, 2023, which application is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63616080 | Dec 2023 | US |
