The present disclosure relates to substrate etching and deposition processes, and more particularly to atomic layer etching and deposition.
The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
During atomic layer etching (ALE) of a substrate, such as a semiconductor wafer, a monolayer of the substrate is removed during each cycle. A reactant gas is introduced into a processing chamber to modify a surface of the substrate. For example, a gas including a halide species is often used during ALE of silicon (Si), germanium (Ge) and metal oxides (MOx) to provide a halide-infused top layer. For example, gas including molecular chlorine species may be introduced to convert a surface layer of a Si substrate from Si to silicon chloride (SiClx), where x is 1, 2, 3, or 4. After surface layer modification, the processing chamber is purged. Plasma is used to remove the modified surface layer followed by purging of by-products.
During metal ALE of a substrate, a metal ligand is introduced using a metal precursor to modify a metal oxide surface of the substrate. Metal ALE is limited in speed and selectivity. Using plasma during ALE can cause structural damage. For example, substrates including magnetic random access memory (MRAM) devices may be damaged. Metal ALE is also limited to removal of certain types of metals.
An ALE system for performing a metal ALE process to etch a surface of a substrate is provided. The ALE system includes a processing chamber, a substrate support, a first heat source, a delivery system, and a controller. The substrate support is disposed in the processing chamber and is configured to support the substrate. The delivery system is configured to supply at least one of a ligand or an organic species to the processing chamber. The controller is configured to control the delivery system and the first heat source to perform an isotropic metal ALE process. The isotropic metal ALE process includes: during an iteration of the isotropic metal ALE process, performing atomistic adsorption and pulsed thermal annealing; during the atomistic adsorption, exposing the surface of the substrate to the at least one of the ligand or the organic species, where the at least one of the ligand or the organic species is void of a metal precursor and is selectively adsorbed to form a metal complex in the surface of the substrate; and during the pulsed thermal annealing, pulsing the first heat source on and off multiple times to remove the metal complex from the substrate.
In other features, the surface includes at least one of a metal, a metal oxide, or a metal nitride. In other features, during the isotropic metal ALE process, the surface of the substrate is not exposed to a metal precursor.
In other features, the isotropic metal ALE process includes preheating the substrate, via a second heat source, prior to performing the atomistic adsorption. In other features, the isotropic metal ALE process includes preheating the substrate to a temperature greater than or equal to an ambient temperature and less than a boiling point temperature of the metal complex.
In other features, the isotropic metal ALE process includes modifying the surface prior to performing the atomistic adsorption. In other features, the modifying of the surface includes supplying a gas to react with the surface of the substrate without striking plasma. In other features, the modifying of the surface includes supplying a gas to react with the surface of the substrate and striking plasma. In other features, the surface includes the metal and the modifying of the surface includes converting the metal to a metal oxide or a metal halide.
In other features, during the atomistic adsorption, the surface of the substrate is exposed to the ligand. The ligand is a reactive free ligand. In other features, the ligand is selected from a group consisting of hexafluroacetylacetone (Hhfac) and acetylacetone (Hacac). In other features, the ligand is selected from a group consisting of molecular chlorine (Cl2), ethanol (EtOH), and an organic vapor.
In other features, the isotropic metal ALE process includes a first modification operation and a second modification operation. The atomistic adsorption corresponds to the second modification operation. The controller is configured to perform a predetermined number of iterations of the isotropic metal ALE process. Each of the predetermined number of iterations includes at least one of (i) supplying a different chemical species during the first modification operation than is supplied during a previous iteration of the isotropic metal ALE process, or (ii) supplying a different chemical species during the second modification operation than is supplied during a previous iteration of the isotropic metal ALE process.
In other features, a metal ALE method for etching a surface of a substrate is provided. The metal ALE method includes: disposing the substrate on a substrate support in a processing chamber; a delivery system configured to supply at least one of a ligand or an organic species to the processing chamber; and performing an isotropic metal ALE process. The isotropic metal ALE process includes: during an iteration of the isotropic metal ALE process, performing atomistic adsorption and pulsed thermal annealing; during the atomistic adsorption, exposing the surface of the substrate to the at least one of the ligand or the organic species, where the at least one of the ligand or the organic species is void of a metal precursor and is selectively adsorbed into the surface of the substrate to form a metal complex; and during the pulsed thermal annealing, pulsing a heat source on and off multiple times to remove the metal complex from the substrate.
In other features, the surface includes at least one of a metal, a metal oxide, or a metal nitride. In other features, during the isotropic metal ALE process, the surface of the substrate is not exposed to a metal precursor. In other features, the isotropic metal ALE process includes preheating the substrate prior to performing the atomistic adsorption to a temperature greater than or equal to an ambient temperature and less than a boiling point temperature of the metal complex.
In other features, the isotropic metal ALE process includes modifying the surface prior to performing the atomistic adsorption. In other features, the modifying of the surface includes supplying a gas to react with the surface of the substrate without striking plasma. In other features, the modifying of the surface includes supplying a gas to react with the surface of the substrate and striking plasma. In other features, the surface includes the metal and the modifying of the surface includes converting the metal to a metal oxide or a metal halide.
In other features, during the atomistic adsorption, the surface of the substrate is exposed to the ligand and the ligand is a reactive free ligand. In other features, the ligand is selected from a group consisting of hexafluroacetylacetone (Hhfac) and acetylacetone (Hacac). In other features, the ligand is a reactive free ligand selected from a group consisting of molecular chlorine (Cl2), ethanol (EtOH), and an organic vapor.
In other features, the isotropic metal ALE process includes a first modification operation and a second modification operation. The atomistic adsorption corresponds to the second modification operation. A predetermined number of iterations of the isotropic metal ALE process are performed. Each of the predetermined number of iterations includes at least one of (i) supplying a different chemical species during the first modification operation than is supplied during a previous iteration of the isotropic metal ALE process, or (ii) supplying a different chemical species during the second modification operation than is supplied during a previous iteration of the isotropic metal ALE process.
In other features, an ALE system for performing a metal ALE process to etch a surface of a substrate is provided. The ALE system includes a processing chamber, a substrate support, a heat source, a delivery system and a controller. The substrate support is disposed in the processing chamber and configured to support the substrate. The heat source is configured to heat at least one of the substrate support or the processing chamber. The delivery system is configured to supply at least one of a ligand or an organic species to the processing chamber. The controller is configured to control the delivery system and the heat source to perform an isotropic metal ALE process including. During an iteration of the isotropic metal ALE process, the surface is modified and atomistic adsorption and thermal annealing are performed. During the modifying of the surface, a gas is supplied to react with the surface of the substrate. During the atomistic adsorption, the surface of the substrate is exposed to the at least one of the ligand or the organic species. The at least one of the ligand or the organic species is void of a metal precursor and is selectively adsorbed to form a metal complex in the surface of the substrate. During the thermal annealing, the heat source is activated to remove the metal complex from the substrate.
In other features, the gas includes oxygen (O2). In other features, the ligand includes chlorine (Cl2). In other features, the thermal annealing includes (i) not pulsing the heat source, or (ii) pulsing the heat source with extended pulses having lengths greater than or equal to a predetermined length.
In other features, an ALE system for performing a metal ALE process to etch a surface of a substrate is provided. The ALE system includes a processing chamber, a substrate support, a heat source, a delivery system, and a controller. The substrate support is disposed in the processing chamber and configured to support the substrate. The heat source is configured to heat at least one of the substrate support or the processing chamber. The delivery system is configured to supply at least one of a ligand or an organic species to the processing chamber. The controller is configured to control the delivery system and the heat source to perform a selective metal ALE process including: during an iteration of the selective metal ALE process, modifying the surface, performing atomistic adsorption and pulsed thermal annealing; and during the modifying of the surface, supplying a gas to react with selective portions of the surface of the substrate. The modifying of the surface includes at least one of (i) biasing the selective portions of the surface, (ii) supplying the gas at a pressure below a predetermined pressure, or (iii) maintaining a pressure within the processing chamber at less than the predetermined pressure. During the atomistic adsorption, the surface of the substrate is exposed to the at least one of the ligand or the organic species. The at least one of the ligand or the organic species is void of a metal precursor and is selectively adsorbed to form a metal complex in the surface of the substrate. During the rapid thermal annealing, the heat source is pulsed on and off multiple times to remove the metal complex from the substrate.
In other features, the gas includes oxygen (O2) or hydrogen (H2). In other features, the ligand includes chlorine (Cl2). In other features, the portions of the surface include (i) a bottom portion of a top layer in a hole of an intermediate layer of the substrate, and (ii) a top portion of the top layer disposed on the intermediate layer. In other features, the portions of the surface do not include a sidewall portion of the top layer disposed on a sidewall of the hole.
Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
In the drawings, reference numbers may be reused to identify similar and/or identical elements.
Traditional metal ALE (sometimes referred to as “thermal ALE”) is limited in speed, etch rate, surface adsorption coverage, selectivity and removal of certain metals from a substrate. Traditional metal ALE processes typically include preheating a substrate and introducing a metal precursor along with a ligand to modify a metal oxide surface of a substrate. The introduction of the metal precursor can result in metal contamination of the substrate. In addition, the surface modification performed can result in surface materials having low volatility, which negatively affects removal efficiency. Thus, traditional metal ALE processes have low etch rates (e.g., 0.1 Å/cycle). Also, the ligand may be introduced at temperatures between 300-400° C. At these temperatures, the amount of adsorbed ligand is low.
The examples set forth herein include performing metal ALE processes using organic vapors as ligands without metal precursors to provide metal complex layers. The organic vapors are introduced at low temperature (e.g., temperatures less than a boiling point of the metal complex layers), which increases the amount of organic vapor that is adsorbed. Pulsed thermal heating is used to remove the metal complex layers.
The ALE process allows the ligands to react with surface materials (e.g., metal oxide layers) of a substrate at low temperature to produce volatile materials. The volatile materials are removed using pulsed thermal heating. The metal ALE processes have short cycle times, are depth selective and produce efficient surface modification and removal. In some examples, the metal ALE is up to 100 times faster than traditional metal ALE processes. The metal ALE processes include ligand soaking of exposed surface material at low temperature. The soaked volatile surface material is exposed to high temperature to avoid re-deposition (side reactions).
The examples set forth herein include rapid thermal pulsing (RTP) systems for performing RTP cycles via heat sources to rapidly increase the temperature of upper and/or outer portions of substrates. By rapidly heating the upper and/or outer portions and not heating bases or bulk portions of the substrates, the upper and/or outer portions of the substrates are able to rapidly decrease in temperature after the heat sources are deactivated. Heating and cooling cycles may be performed very quickly as described below. Since the RTP heats a thin outer layer, thermal budget issues are avoided. In other words, thermal heating of a lower bulk portion of a substrate is substantially decreased or avoided. As an example, heating of the thin outer layer may be limited to a few hundred nanometers.
The RTP operations also enable performance of processes that were previously not performed due to sensitivity to thermal budget issues. As an example, isotropic and selective removal of certain upper and/or outer material layers from substrates may be performed. The upper and/or outer material layers may include film materials, which may include metals, metal oxides and/or metal nitrides. Some examples of metals that may be etched are tantalum (Ta), ruthenium (Ru), tungsten (W), cobalt (Co), platinum (Pt), aluminum (Al), barium (Ba), calcium (Ca), chromium (Cr), copper (Cu), erbium (Er), neodymium (Nd, nickel (Ni), palladium (Pd), strontium (Sr), tin (Sn), yttrium (Y), zinc (Zn), zirconium (Zr), hafnium (Hf), and titanium (Ti). Some examples of metal oxides that may be etched are aluminum oxide (Al2O3), hafnium oxide (HfO2), zirconium oxide (ZrO2), yitrium oxide (Y2O3), tin oxide (SnOx), and zinc oxide (ZnO). Some examples of metal nitrides that may be etched are titanium nitride (TiN), tantalum nitride (TaN), and aluminum nitride (AlN).
Referring now to
One or more sensors 119 such as temperature and/or pressure sensors may be arranged in the processing chamber 108 to sense temperature and/or pressure, respectively. A valve 122 and pump 124 may be used to control pressure within the processing chamber 108 and/or to evacuate reactants from the processing chamber 108.
The RTP system 106 includes a heat source 126 that performs rapid thermal annealing of the substrate 112. This includes RTP via flash lamps 128. An example of another RTP system that is laser based is shown in
A temperature control system 150 may be used to control a temperature of the substrate support 110 and the substrate 112. The temperature control system 150 may control supply of a fluid from a fluid source 152 via a pump 154 that is connected to the fluid channels 114. The temperature control system 150 may also control operation of the heaters 116. The temperature control system 150 may include one or more temperature sensors 156 to sense temperatures of one or more locations or zones of the substrate support 110.
A delivery system 160 includes one or more sources 164, one or more valves 106, one or more mass flow controllers 168 and a mixing manifold 170. The delivery system 160 selectively supplies gases, vapors, liquids, chemicals, plasma gas mixtures, carrier and/or inert gases, and/or purge gas mixtures to the processing chamber 108 during pretreatment, doping, passivation, surface modification, atomistic adsorption, annealing and/or purging.
An RF generator 120-1 includes an RF source 123 and a matching network 125 that outputs RF power to a coil 127, which surrounds an outer wall of the processing chamber 108. The RF generator 120-1 creates a magnetic field in the processing chamber 108 that strikes plasma. Another RF generator 120-2 may be used to supply an RF bias to the electrode 118 in the substrate support 110. A controller 180 communicates with the one or more sensors 119, the valve 122 and pump 124, the temperature control system 150, the heat source 126, the RF generators 120-1 and/or 120-2, and the delivery system 160 to control the process being performed.
The controller 180 may include a RTP controller 182, which controls a capacitive discharge circuit 184 to pulse the flash lamps 128. The capacitive discharge circuit 184 may receive power from a power source 186 and a control signal from the RTP controller 182. The capacitive discharge circuit 184 may charge capacitors (represented by box 187) when in an idle mode and may discharge the capacitors upon receiving a discharge signal from the RTP controller 182. The RTP controller 182 may perform RTP operations during metal ALE and/or metal ALD processes.
The lens circuit 206 includes beam shaping optics 212, a Galvano mirror circuit 213 that includes a first mirror 214 and a second mirror 216, and a tele-centric lens assembly 218. The beam shaping optics 212 may include flat-top (or first beam shaping) optics 220 and diffractive (or second beam shaping) optics 222. The flat-top optics 220 are used to convert a laser beam received from the laser 204, where the laser beam has a Gaussian distribution, into a flat-top beam (e.g., a 2 centimeter (cm)×2 cm flat-top beam). A temperature profile of the laser beam is also Gaussian. An example of a flat-top optic is a “flywheel” optic.
The diffractive optics 222 convert the flat-top circular beam out of the flat-top optics 220 to a square beam. The square beam has a corresponding uniform temperature distribution on a substrate. This allows for a uniform thermal reaction and/or etch rate over the portion of a substrate (e.g., substrate 112) exposed to the square beam. Providing a square beam also provides a beam with a shape that matches a shape of a die being heated. The square beam may uniformly heat a surface or an upper portion of a selected die. The substrate 112 may be disposed on the substrate support in the processing chamber 108.
A beam size adjustment device 226 may be disposed between the beam shaping optics 212 and the first mirror 214. The beam size adjustment device 226 may adjust a size of the square beam to be greater than or equal to a size of a die on the substrate 112. The beam size adjustment device 226 may be motorized and include a beam expander 227. The beam expander 227 may perform magnification and increase a size of the laser beam.
The RTP controller 210 and the Galvano mirror circuit 113 may operate as a X-Y galvanometer scanning system. The first mirror 214 may be used to move the laser beam across a surface of the substrate 112 in a first (or X) direction. The second mirror 216 may be used to move the laser beam across the surface of the substrate in a second (or Y) direction. The controller 208 and/or the RTP controller 210 may move the mirrors 214, 216 via motors 230, 232.
The tele-centric lens assembly 218 may be referred to as a collimating assembly and includes a series of plano-convex lenses 240, 242, 244, 246. Although a particular number of plano-convex lenses are shown, a different number of plano-convex lenses may be included. The diameter of the plano-convex lenses 240, 242, 244, 246 increases the closer the plano-convex lens is to the window assembly 130, such that: a diameter of the lens 242 is larger than a diameter of the lens 240; a diameter of the lens 244 is larger than the diameter of the lens 242; and a diameter of the lens 246 is larger than the diameter of the lens 244. The plano-convex lenses 240, 242, 244, 246 are vertically aligned to have a common centerline 248. The plano-convex lenses 240, 242, 244, 246 are held in a fixed relationship within a mold 250. The plano-convex lenses 240, 242, 244, 246 direct the laser beam received from the second mirror 216 to be orthogonal to the surface of the substrate 112. As the laser beam is moved across the surface of the substrate 112, the tele-centric lens assembly 218 maintains the laser beam in an orthogonal relationship with the surface of the substrate 112.
As an example, the laser beam generated by the laser 204 may be 355 nm in diameter and may be pulsed every 80 picoseconds (ps). The RTP controller 210 may move the mirrors 214, 216 to perform 150 Hertz (Hz) scan across the surface of the substrate 112.
The substrate processing system 200 may include the temperature control system 150, which may be used to control a temperature of the substrate support 110 and the substrate 112. The temperature control system 150 may include the one or more temperature sensors 156 to sense temperatures of one or more locations or zones of the substrate support 110.
The Galvano mirror circuit 213 of
A flange focal length (FFL) and a back focal length (BFL) are shown. The FFL may be a distance from (i) an end of a flange 305 and/or a point 307 where the lens 246 begins to curve and protrude outward towards the image plane 304, and (ii) the image plane 304. The BFL may refer to a distance from (i) a point 309 on the lens 246 closest to the image plane 304, and (ii) the image plane 304.
The above-described examples of
During pretreatment (or a first surface modification operation), molecular oxygen (O2) plasma, ozone (O3), hydrogen peroxide (H2O2), water vapor plasma, molecular hydrogen (H2) plasma, molecular chlorine (Cl2) plasma, ammonia (NH3) plasma, and/or other gas may be supplied. During pretreatment, a plasma may be provided to modify a surface and/or portion of a substrate.
During the second surface modification operation, a metal-free ligand in the form of an organic gas or vapor is introduced. The metal-free ligand may include a reactive free ligand, such as hexafluroacetylacetone (Hhfac) and/or acetylacetone (Hacac), and/or other organic gas, vapor and/or reactant to be adsorbed into the surface and/or portion of the substrate. The metal-free ligand may include molecular chlorine (Cl2), ethanol (EtOH), or other organic vapor. Other example ligands that may be used are trifluroacetic acid, acetic acid, acetonitrile, dimethylformamide, tetramethylethlyenediamine, tert-butyl isocyanide, tert-butylamine, dimethylamine, tert-butyl alcohol, and tert-butylthiol. Different variations of Hacac may be used including, for example, various compounds including two or more of carbon (C), fluorine (F), hydrogen (H), oxygen (O), sulfur (S), nitrogen (N), phosphorus (P), selenium (Se), and arsenic (As) elements. Other examples variations of Hacac that may be used are: acetylacetone; trifluoroacetylacetone; hexafluoroacetylacetone; dipivaloylmethane; pivaloyltrifluoroacetone; dibenzoylmethane; 4, 4, 4-trifluoro-1-phenyl-1,3-butanedione; 4,4-difluoro-1-phenyl-1,3-butanedione; 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione; and 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione.
The portion of the substrate subjected to atomistic adsorption may be formed of a metal, a metal oxide, or a metal nitride. Some examples of metals that may be etched are tantalum (Ta), ruthenium (Ru), tungsten (W), cobalt (Co), platinum (Pt), aluminum (Al), barium (Ba), calcium (Ca), chromium (Cr), copper (Cu), erbium (Er, neodymium (Nd), nickel (Ni), palladium (Pd), strontium (Sr), tin (Sn), yttrium (Y), zinc (Zn), zirconium (Zr), hafnium (Hf), and titanium (Ti). Some examples of metal oxides (MOx) that may be etched are aluminum oxide (Al2O3), hafnium oxide (HfO2), zirconium oxide (ArO2), yitrium oxide (Y2O3), tin oxide (SnOx), and zinc oxide (ZnO). Some examples of metal nitrides that may be etched are titanium nitride (TiN), tantalum nitride (TaN), and aluminum nitride (AlN).
Subsequent to atomistic adsorption, the portion being removed may be a metal complex, for example including: a metal and a ligand, water, hydrogen, trimethylsilyl chloride, and/or other volatile and modified materials and/or substances.
In an embodiment, a predetermined number of cycles are performed to remove a predetermined amount of one or more layers of a substrate. As an example, a monolayer of an uppermost portion of a substrate may be removed per cycle of the metal ALE process. During the rapid thermal operation, a flash lamp assembly or a laser may be used as shown in
The substrates may cool down during the surface refresh operations. The surface refresh operation may include the introduction of argon (Ar) gas. In one embodiment, active cooling is provided to cryogenically cool the substrates. This shortens the amount of time to cool down the substrates and allows for more cycles to be performed in a shortened period of time. Active cooling provides quick recovery without negatively affecting the base (or bulk) portion of the substrates.
As an example, the low temperature pulses may be provided to increase temperatures of a portion of a substrate to 80° C. per cycle. The high temperature pulses may increase temperatures of the portion of the substrate to 600° C. per cycle. In one embodiment, the low temperature pulses increase temperatures of the portion of the substrate to 20-80° C. In one embodiment, the high temperature pulses increase temperatures of the portion of the substrate to 100-600° C. In another embodiment, the low temperature pulses are not provided. The portion of the substrate being heated is cooled down for example to a baseline temperature (e.g., 20° C.) between each consecutive pair of the low temperature pulses and/or the high temperature pulses. Multiple low temperature and/or high temperature pulses may be provided and the portion of the substrate being heated may cool down between sequential ones of the pulses over a predetermined number of seconds (shown as x seconds). As an example, multiple low temperature pulses and high temperature pulses may be provided over a 3-10 second long period.
The RTP described herein allows for heating and controlling substrate surface temperatures. Heating is provided to predetermined depths of a substrate in a controlled and tunable manner while providing atomistic reaction control. This may be accomplished by controlling the number, length, intensity, and frequency of the light (e.g., flash lamp or laser) pulses being generated. In one embodiment, a series of high temperature pulses are provided. In other embodiment, a series of low temperature pulses are provided. In another embodiment, a combination of low temperature and high temperature pulses are provided and the durations, intensities (or power levels) and frequencies of the pulses are controlled to provide a temperature depth profile across at least a portion of a surface of a substrate. By having multiple flash lamps as in the embodiment of
The following examples of
The rows and columns provide cells, where each cell includes 0, 1, 2, or 3 symbols in a particular order. The symbols include a circle, a square and a triangle. The circle refers to introducing molecular oxygen (O2) plasma and the ligand Hhfac followed by flash lamp heating. The triangle refers to introducing ozone O3 gas) followed by flash lamp heating. The square refers to introducing molecular oxygen (O2) plasma and molecular chlorine (Cl2) followed by flash lamp heating. Although
The systems disclosed herein may be operated using numerous methods, example methods are illustrated in
The method may begin at 1100. At 1102, a substrate (e.g., the substrate 112 of
At 1106, a surface of the substrate is cleaned. As an example the substrate may include an upper (or top) layer that is disposed on a base layer. The upper layer may include or consist of a metal, a metal oxide or a metal nitride. The upper surface of the upper layer may be cleaned.
At 1108, pretreatment may be performed including exposing one or more surfaces and/or layers of the substrate that include a metal, a metal oxide or a metal nitride with, for example, molecular oxygen (O2) plasma, ozone (O3), hydrogen peroxide (H2O2), water vapor plasma, hydrogen (H2) plasma, molecular chlorine (Cl2) plasma, hydrazine (N2H4), ammonia (NH3) plasma, and/or other gas. The surface modification may include a non-plasma process, such as flow of chemicals, hydrogen peroxide (H2O2) vapor, water (H2O) vapor, hydrazine (N2H4), and/or other chemical reactant. In another embodiment, the surface modification includes a plasma process, such as flow of molecular oxygen (O2) plasma, molecular hydrogen (H2) plasma, an ammonia (NH3) plasma, a water (H2O) plasma, and/or other plasma. As an example, this may include supplying O2 plasma to convert TiN (Ti3+) to TiO2 (Ti4+), which may occur at room temperature or at other temperatures. Operation 1108 may be performed to convert a metal to a metal oxide or a metal halide. This operation may be performed for de-chlorination and surface activation. As an example, a plasma gas mixture including hydrogen (H2) gas or ammonia (NH3) gas species is supplied to the processing chamber. In one embodiment, surface modification is performed without plasma, but by using gases having a preselected chemistry.
At 1109, the substrate is optionally preheated. This may include increasing temperature of the substrate support and/or temperature within the corresponding processing chamber as described above. As an example, the temperature of the substrate, substrate support, and/or interior of the processing chamber may be increased to a predetermined temperature (e.g., 200° C.). In an embodiment, operation 1109 is not performed and the substrate is maintained at a room temperature. In one embodiment, the temperature of the substrate, substrate support and/or interior of the processing chamber are at temperatures greater than or equal to a room temperature and less than a boiling point of a complex metal to be formed as a result of performing the following operation 1110.
At 1110, atomistic adsorption is performed including introduction of one or more reactive free ligands, such as hexafluroacetylacetone Hhfac and/or acetylacetone Hacac, and/or introduction of one or more other organic gases, vapors and/or reactants to be adsorbed into the substrate. The metal-free ligand may include molecular chlorine (Cl2), ethanol (EtOH), and/or other organic vapor. In an embodiment, the metal-free ligand is Cl2. This operation includes converting one or more upper and/or outer surfaces/layers of the substrate that was modified at 1108 into a layer having a metal complex. Operation 1110 may occur at temperatures, for example, greater than or equal to a room (or ambient) temperature and less than a boiling point of the metal complex. The one or more ligands introduced may be selected based on the metal, metal oxide, and/or metal nitride being etched, the pre-treatment performed, the temperature of the surface/layer being etched, the energy level used for etching, etc. This enables precise and highly selective etching including selective etch depths and etch rates for surfaces having different metals and/or metal compounds.
At 1112, the corresponding process chamber is purged of gases. At 1114, pulsed rapid thermal annealing is performed using, for example, flash lamps, a laser or other suitable lamps (e.g., infrared lamps) capable of being rapidly pulsed as described herein. In an embodiment, flash lamps are utilized providing a predetermined amount of thermal energy (e.g., 7 Joules (J) or 11 J). In another embodiment, pulsed laser is utilized.
At least operations 1108-1115 may be iteratively performed including modulating surface or upper portion temperatures of the substrate. The temperature of the surface or upper portion may be modulated multiple times in a single second. Pulsed rapid thermal annealing is performed at 1114 for desorption/removal purposes. This may include generating one or more thermal energy pulses to heat the modified portion of the substrate. Temperatures may be increased to evaporate certain molecules. Rapid thermal pulsing enables a clean reaction at surface of substrate, which frees the metal complex from the substrate.
As an example, a substrate may have a metal oxide layer including hafnium oxide, which is to be etched. At 1108, chlorination may be performed including introducing a chloride plasma and/or gas to convert HfO2 to HfCl4. Then at 1110, an organic gas, compound, and/or ligand, such as N, N-dimethytrimethylsilylamine (TMSDMA) or Hhfac may be introduced. At 1114, a metal dimethylamidos (e.g., metal-dimethylamine (Hf(DMA)4)) and a highly volatile liquid (e.g., trimethylsilyl chloride TMSCl) may be removed if TMSDMA or the like was introduced at 1110. Hf(DMA)4 and TMSCl may be removed if TMSDMA was introduced at 1110. Metal dimethylamidos are volatile and may be used as a vapor precursor. The described method may be performed to remove high boiling point halides, such as HfCl4 (or metal chloride), by converting the high boiling point metal halide to a volatile organometallic compounds and an organosilicon compound (or volatile liquid), At 1114, Hf(hfac)4 and HCl may be removed if Hhfac was introduced at 1110.
As another example, a substrate may have a metal layer or a metal oxide layer, such as a layer of hafnium or a layer of hafnium oxide, which is to be etched. At 1108, an oxygen plasma may be introduced followed by at 1110 an introduction of Hhfac. At 1114, Hf(hfac)4 and H2O may be removed.
As yet another example a substrate may have a metal layer or a metal oxide layer, such as a layer of hafnium or a layer of hafnium oxide, which is to be etched. At 1108, hydrogen plasma and optionally oxygen plasma may be introduced followed by at 1110 an introduction of Hhfac. At 1114, Hf(hfac)4, H2O and H2 may be removed.
No inorganic salt or additional metal complex is produced when performing the above stated operations. An additional metal complex can be produced when, for example, a metal precursor is introduced. The above operations do not include introduction of a metal precursor. Incomplete organic residual may be cleaned easily by introducing hydrogen plasma or oxygen plasma in a surface refresh operation, such as at 1115.
A base and/or bulk of the substrate is maintained at or below a predetermined temperature (e.g., less than or equal to 20° C.) during operation 1114. RTP enables one processing chamber configuration to be used with high throughput. Multiple processing operations may be performed in the single processing chamber. As another example, each of the pulses may be 0.1 millisecond (ms) in length and a temperature of a surface and/or a portion of the substrate may be increased up to 1000° C.
In some examples, each of the flash lamp pulses provides 5 J/cm2 (i.e., energy per unit area of the substrate) to 80 J/cm2. In some examples, each of the laser pulses provides 5 mJ/cm2 to 80 mJ/cm2. In some examples, the annealing is performed during a predetermined period in a range from 0.1 ms to 20 ms. In one embodiment, the flash lamp is used with pulse durations of 1 ms or the laser is used with pulse durations of 1 picosecond (ps) to heat the surface or upper portion of the substrate from an initial temperature to greater than 500° C. and then cooled back down to the initial temperature in less than 1 second (s).
Operations 1108, 1110, 1114 allow for controllable atom by atom removal of a surface and/or upper layer of the substrate that was modified during operations 1108 and 1110. The rapid heating performed at 1114 provides an isotropic reaction without use of plasma. In addition, the claimed heating allows for rapid cool down, which also prevents thermal budget issues.
At 1115, the surface of the substrate may be refreshed by purging the process chamber with a purge gas (e.g., argon (Ar) gas) to perform ion bombardment and remove the modified portion(s) of the substrate. In one embodiment, the processing chamber is purged between one or more consecutive pairs of provided rapid thermal pulses. In an embodiment, the gases are purged from the processing chamber between each consecutive pair of pulses. This enables performance of multiple plasma and/or gas phase processes within the processing chamber. In an embodiment, substrate support cooling is provided during and/or subsequent to pulsed rapid thermal annealing to aid in maintaining temperatures of the base and/or bulk of the substrate during pulsed rapid thermal annealing and to aid in rapid cooling of the substrate subsequent to performing pulsed rapid thermal annealing.
At 1116, the controller 180 or 208 and/or rapid thermal pulse controller 182 or 210 determines whether N cycles have been completed, where N is an integer greater than or equal to 1. If N cycles have been completed, operation 1118 is performed, otherwise operation 1108 is performed. At 1118, the controller 180 or 210 may optionally perform a second (or post) annealing operation. At 1119, the controller 180 or 210 may determine, for a current die, whether to perform another process and/or whether to change and/or reiterate a current process. If another process is to be performed, operation 1104 may be performed, otherwise operation 1120 may be performed when a laser and a lens circuit is utilized as in the embodiment of
At 1124, the controller 208 moves the mirrors 214, 216 to change an image plane position of a laser beam to be over a different die of the substrate 112. As an example, a 2 cm×2 cm laser beam may be moved from being over a first die to being over a second die. The described method may be iteratively performed to scan the laser beam over tens to hundreds of dies on the substrate. Movement of the mirrors 214, 216 may be synchronized with a pulsing repetition rate of the laser 204 to provide one or more shots per die.
The above-described operations are meant to be illustrative examples. The operations may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods or in a different order depending upon the application. Also, any of the operations may not be performed or skipped depending on the implementation and/or sequence of events.
Although the method of
The lens circuit 1206 includes beam shaping optics 1212, a Galvano mirror circuit 1213 that includes a first mirror 1214 and a second mirror 1216, and a tele-centric lens assembly 1218. The beam shaping optics 1212 may include flat-top (or first beam shaping) optics 1220 and diffractive (or second beam shaping) optics 1222. The flat-top optics 1220 are used to convert a laser beam received from the laser 1204, where the laser beam has a Gaussian distribution, into a flat-top beam (e.g., a 2 centimeter (cm)×2 cm flat-top beam). A temperature profile of the laser beam is also Gaussian. The diffractive optics 1222 convert the flat-top circular beam out of the flat-top optics 1220 to a square beam. The square beam has a corresponding uniform temperature distribution on a substrate. The substrate 112 may be disposed on a substrate support (e.g., the substrate support 110 of
The laser 1204 may be operated in a pulse mode or a continuous wave (CW) mode. During the pulse mode, the output of the beam shaping optics 1212 may be provided directly to the beam size adjustment device 1226. During the pulse mode, the RTP controller 1210 controls a pulse rate of the laser beam, such that pulse duration is in a pico-second or a nanosecond range. An acousto-optic modulator 1223 may be included when the laser 1204 is being operated in the CW mode and be controlled by the RTP controller 1210. In one embodiment, the RTP controller 1210 generates a radio frequency (RF) control signal, which is provided to the acousto-optic modulator 1223. The RF control signal is provided to control a change in a refractive index of a crystal of the acousto-optic modulator 1223. The refractive index of the crystal changes based on a frequency of the RF control signal. The laser beam provided from the beam shaping optics 1212 to the acousto-optic modulator 1223 is deflected by the crystal based on a frequency of the RF signal. The crystal performs as a laser shutter that permits or prevents passage of the laser beam to the beam size adjustment device 1226 and/or the first mirror 1214. In one embodiment, the RTP controller 1210 controls the frequency of the RF control signal, such that the continuous wave laser beam out of the beam shaping optics 1212 is effectively pulsed (or modulated) by the acousto-optic modulator 1223. The laser beam is pulsed, such that a period of each pulse is in a micro-second or a millisecond range. As a result, use of the acousto-optic modulator 1223 allows for pulsed laser beam generation having longer duration pulses for increased heating per pulse.
The beam size adjustment device 1226 may be disposed between the beam shaping optics 1212 and the first mirror 1214. In an embodiment, the beam size adjustment device 1226 adjusts a size of the square beam to be greater than or equal to a size of a die on the substrate 112. The beam size adjustment device 1226 may be motorized and include a beam expander 1227.
The RTP controller 1210 and the Galvano mirror circuit 1213 may operate as a X-Y galvanometer scanning system. The first mirror 1214 may be used to move the laser beam across a surface of the substrate 112 in a first (or X) direction. The second mirror 1216 may be used to move the laser beam across the surface of the substrate in a second (or Y) direction. The controller 1208 and/or the RTP controller 1210 may move the mirrors 1214, 1216 via motors 1230, 1232.
The tele-centric lens assembly 1218 may include a series of plano-convex lenses 1240, 1242, 1244, 1246. Although a particular number of plano-convex lenses are shown, a different number of plano-convex lenses may be included. The diameter of the plano-convex lenses 1240, 1242, 1244, 1246 increases the closer the plano-convex lens is to the window assembly 130, such that: a diameter of the lens 1242 is larger than a diameter of the lens 1240; a diameter of the lens 1244 is larger than the diameter of the lens 1242; and a diameter of the lens 1246 is larger than the diameter of the lens 1244. The plano-convex lenses 1240, 1242, 1244, 1246 are vertically aligned to have a common centerline 1248. The plano-convex lenses 1240, 1242, 1244, 1246 are held in a fixed relationship within a mold 1250. The plano-convex lenses 1240, 1242, 1244, 1246 direct the laser beam received from the second mirror 1216 to be orthogonal to the surface of the substrate 112. As the laser beam is moved across the surface of the substrate 112, the tele-centric lens assembly 1218 maintains the laser beam in an orthogonal relationship with the surface of the substrate 112.
As an example, a laser beam out of the beam shaping optics 1212, the acousto-optic modulator 1223 and/or the beam size adjustment device 1226 may be focused at the a center 1252 of the second mirror 1216 and then be directed through the tele-centric lens assembly 1218, where the laser beam is collimated and provided to the substrate 112. Focusing the laser at an input pupil of the second mirror (or lens) 1216 aids in providing a collimated beam at an upward facing surface of the substrate 112.
As an example, the laser beam generated by the laser 1204 may be 355 nm in diameter. The laser 1204 may operate in the pulse mode or the CW mode. The beam shaping optics 1212, the beam size adjustment device 1227, and the tele-centric lens assembly 1218 may generate a 2 centimeter by 2 centimeter square beam that is received at the substrate 112. The RTP controller 1210 may move the mirrors 1214, 1216 to perform a 200 Hz scan across a surface of the substrate 112. The RTP controller 1210 may scan over all dies and/or an upward facing surface area (e.g., for a 300 mm diameter substrate, the 2.83×105 mm upward facing surface area of the substrate) within a 1 second period of time. This may include scanning over, for example, 160 dies of the substrate within 1 second. The scanning includes moving the laser beam from die-to-die and heating each die for a predetermined period of time (e.g., an overall period of one or more pulses of the laser beam).
The substrate processing system 1200 may include the temperature control system 150, which may be used to control a temperature of the substrate support 110 and the substrate 112. The temperature control system 150 may include the one or more temperature sensors 156 to sense temperatures of one or more locations or zones of the substrate support 110.
A tele-centric lens assembly, as shown in
In order to reduce the distance between the mirror 216 and at the same time collimate the laser beam, an optical beam folding assembly may be incorporated between the mirror 216 and the image plane 304. The optical beam folding assembly improves tele-centricity. An example of this is shown in
The lens circuit 1406 includes beam shaping optics 1412, a Galvano mirror circuit 1413 that includes a first mirror 1414 and a second mirror 1416, and an optical beam folding assembly 1418. The beam shaping optics 1412 may include flat-top (or first beam shaping) optics 1420 and diffractive (or second beam shaping) optics 1422. The flat-top optics 1420 are used to convert a laser beam received from the laser 1404, where the laser beam has a Gaussian distribution, into a flat-top beam (e.g., a 2 centimeter (cm)×2 cm flat-top beam). A temperature profile of the laser beam is also Gaussian. The diffractive optics 1422 convert the flat-top circular beam out of the flat-top optics 1420 to a square beam. The square beam has a corresponding uniform temperature distribution on a substrate 112. The substrate 112 may be disposed on the substrate support in the processing chamber 108.
The laser 1404 may be operated in a pulse mode or a continuous wave (CW) mode. During the pulse mode, the output of the beam shaping optics 1412 may be provided directly to the beam size adjustment device 1426. During the pulse mode, the RTP controller 1410 may control a pulse rate of the laser beam, such that pulse duration is in a pico-second or a nanosecond range. An acousto-optic modulator 1423 may be included when the laser 1404 is being operated in the CW mode. The acousto-optic modulator 1423 may be controlled by the RTP controller 1410. In one embodiment, the RTP controller 1410 generates a RF control signal, which is provided to the acousto-optic modulator 1423. The RF control signal is provided to control a change in a refractive index of a crystal of the acousto-optic modulator 1423. The refractive index of the crystal changes based on a frequency of the RF control signal. The laser beam provided from the beam shaping optics 1412 to the acousto-optic modulator 1423 is deflected by the crystal based on a frequency of the RF signal. The crystal performs as a laser shutter that permits or prevents passage of the laser beam to the beam size adjustment device 1426 and/or the first mirror 1414. In one embodiment, the RTP controller 1410 controls the frequency of the RF control signal, such that the continuous wave laser beam out of the beam shaping optics 1412 is effectively pulsed (or modulated) by the acousto-optic modulator 1423. The laser beam is pulsed, such that a period of each pulse is in a micro-second or a millisecond range. As a result, use of the acousto-optic modulator 1423 allows for pulsed laser beam generation having longer duration pulses for increased heating per pulse.
The beam size adjustment device 1426 may be disposed between the beam shaping optics 1412 and the first mirror 1414. The beam size adjustment device 1426 may adjust a size of the square beam to be greater than or equal to a size of a die on the substrate 112. The beam size adjustment device 1426 may be motorized and include a beam expander 1427.
The RTP controller 1410 and the Galvano mirror circuit 1413 may operate as a X-Y galvanometer scanning system. The first mirror 1414 may be used to move the laser beam across a surface of the substrate 112 in a first (or X) direction. The second mirror 1416 may be used to move the laser beam across the surface of the substrate in a second (or Y) direction. The controller 1408 and/or the RTP controller 1410 may move the mirrors 1414, 1416 via motors 1430, 1432.
The optical beam folding assembly 1418 may include a set of mirrors for reflecting a received laser beam. The optical beam folding assembly 1418 may include any number of mirrors. As an example, 4 mirrors 1452, 1454, 1456, 1458 are shown. The mirrors may have different sizes, be positioned at different angles, and be positioned in different locations within a housing 1459. The housing 1459 may have a first (or input) window 1460 and a second (or output) window 1461 through which a laser beam is passed. In the example shown, three laser beams 1462, 1464, 1466 are shown; each of which having respective light rays. The three laser beams are provided at respective times and by moving the mirrors 1414, 1416 to respective positions. Any number of laser beams may be generated. In one embodiment, the Galvano mirror circuit is included in the housing 1459. The Galvano mirror circuit 1413 in combination with the optical beam folding assembly 1418 or the optical beam folding assembly 1418 alone may be referred to as a collimating assembly.
The optical beam folding assembly 1418 increases the distance that the laser beam travels from the second mirror 1416 to the substrate 112 while minimizing distance between the second mirror 1416 and the substrate 112. The increased travel distance collimates the laser beam prior to being received at the substrate. This provides a compact design. The optical beam folding assembly 1418 is also less expensive to manufacture than a tele-centric lens assembly.
The set of mirrors of the optical beam folding assembly 1418 are positioned and oriented to direct the laser beam received from the second mirror 1416 to be orthogonal (or within a predetermined angle of 90° relative) to the surface of the substrate 112. As the laser beam is moved across the surface of the substrate 112, the optical beam folding assembly 1418 maintains the laser beam in this orthogonal or semi-orthogonal relationship with the surface of the substrate 112.
As an example, a laser beam out of the beam shaping optics 1412, the acousto-optic modulator 1423 and/or the beam size adjustment device 1426 may be focused at the a center of the second mirror 1416 and then be directed through optical beam folding assembly 1418, where the laser beam is collimated and provided to the substrate 112. Focusing the laser at an input pupil of the second mirror (or lens) 1416 aids in providing a collimated beam at an upward facing surface of the substrate 112.
As an example, the laser beam generated by the laser 1404 may be 355 nm in diameter. The laser 1404 may operate in the pulse mode or the CW mode. The beam shaping optics 1412, the beam size adjustment device 1427, and the optical beam folding assembly 1418 may generate a 2 centimeter by 2 centimeter square beam that is received at the substrate 112. The RTP controller 1410 may move the mirrors 1414, 1416 to perform a 200 Hz scan across a surface of the substrate 112. The RTP controller 1410 may scan over all dies and/or an upward facing surface area (e.g., for a 300 mm diameter substrate, the 2.83×105 mm upward facing surface area of the substrate) within a 1 second period of time. This may include scanning over, for example, 160 dies of the substrate within 1 second. The scanning includes moving the laser beam from die-to-die and heating each die for a predetermined period of time (e.g., an overall period of one or more pulses of the laser beam).
The substrate processing system 1400 may include the temperature control system 150, which may be used to control a temperature of the substrate support 110 and the substrate 112. The temperature control system 150 may include the one or more temperature sensors 156 to sense temperatures of one or more locations or zones of the substrate support 110.
The processes of ALD and ALE depend on iteratively performing a first operation A followed by a second operation B with a pump/purge operation being performed between operations A and B. This is true independent of the type of heat source utilized. For example, a full wafer surface may be dosed with a first gas to form a saturated monolayer. Any residual amount of the first gas may then be pumped out of a corresponding process chamber. The full wafer surface may then be exposed to second gas and/or an energy source (e.g. energetic ions or ultra-violet photons) followed by a pumping out of product (or remaining) gases. These operations may then be repeated until a predetermined deposited film thickness is obtained or a predetermined etched depth is reached.
For laser-based substrate processing, a laser beam is focused to an area much smaller than that of an upward facing surface area of a substrate (e.g., a 300 mm in diameter substrate having a upward facing surface area of approximately 2800 cm2) in order to heat the surface to a predetermined temperature. In addition, an amount of time to perform pulsed laser annealing (a predetermined number of picoseconds or nanoseconds) is several orders of magnitude smaller than the few seconds typically needed to (i) dose one or more upper and/or outer surfaces of a wafer the full wafer, or (ii) pump out gases in the processing chamber.
Thus, by using the implementations disclosed above, a laser beam may be focused to a size of a chip (or die) of a substrate and the laser beam is then stepped over a surface of the substrate and pulse synchronized with an amount of time involved to reposition the laser beam. Thus, the laser beam is ON when over a chip and is OFF while being transitioned to a next chip.
For example, if a chip has an upward facing surface area of 1 cm×1 cm, then the size of the generated laser beam is also 1 cm×1 cm. As an example, the surface area of a substrate may be dosed followed by pumping out gases and then the laser beam may be stepped from one chip to the next using one of the substrate processing systems disclosed herein. The laser beam may be pulsed ON over each of the chips in succession. Subsequent to pulsing the laser ON over each of the chips of the substrate, the substrate may then be dosed again and this process may be repeated until a predetermined etch depth or a predetermined deposited thickness has been reached for each die. The laser beam may be stepped over all of the chips of a substrate in less than 1-3 seconds, which is similar to an amount of time associated with gas dosing and gas purging operations. Thus, laser annealing time is reduced and substrate throughput is high and inexpensive. This also decreases ON time of the laser and the ratio of time to perform an annealing process on the chips of a substrate relative to the amount of time associated with corresponding dosing and purging.
In one embodiment, a duty cycle of a laser is synchronized with time to steer the associated laser beam from die to die. For example, if there are 160 2 cm-by-2 cm dies on a substrate, then a center of the laser beam is repositioned a distance of a little more than approximately 2 cm (or width of a die plus a gap between adjacent dies) between each laser pulse. If the whole substrate is scanned in a 1 second period of time, then the time associated with each laser pulse cycle is 1/160 seconds.
As an example, an entire substrate may be dosed, gases are pumped out of a corresponding processing chamber, and the laser is stepped from one die to the next pulsing ON over each die in succession. The substrate may then be dosed again and the process is repeated. This provides a quick annealing process. If laser annealing of a full substrate surface took a long time (e.g. 10 minutes), then substrate throughput would be low and expensive. By providing a laser annealing process where a full substrate surface is scanned in a short period of time (e.g., 1 second), the time gating items are substrate dosing and gas purging rather than laser annealing.
The lens circuit 1506 includes beam shaping optics 1512 and at least one of a mirror 1514 and a polygon scanner 1516. In one embodiment, the mirror 1514 is included and the polygon scanner 1516 is not included. In another embodiment, the mirror 1514 is implemented as one side of the polygon scanner 1516. The polygon scanner 1516 may have one or more mirrors. In one embodiment each side surface of the polygon scanner 1516 has a mirror. In the example shown, the polygon scanner has 6 side surfaces and two end surfaces. The polygon scanner may have any number of sides. In one embodiment, the mirror 1514 is rotated via a motor, such as one of the motors of
The motor may be unidirectional or bi-directional, such that a shaft of the motor may be driven in forward and reverse directions. The motor may rotate the mirror and/or polygon scanner, such that a laser beam is no longer being reflected off a first portion of a first mirror, but rather is reflected off a second portion of the first mirror. The shaft of the motor may then be returned to the initial position, such that the laser beam is reflected off the first portion of the first mirror, or may be rotated such that the laser beam is reflected off a different mirror. In one embodiment, the motor is uni-directional and thus the shaft of the motor is rotated in a same direction. Instead of rotating the shaft in a reverse direction and returning to an initial position when rescanning a substrate, the polygon scanner may be rotated such that the laser beam is reflected off of the next adjacent mirror on the polygon scanner. This can have a same effect as returning to the initial position.
The beam shaping optics 1512 may include flat-top (or first beam shaping) optics 1520 and second beam shaping optics 1522. The flat-top optics 1520 are used to convert a laser beam received from the laser 1504, where the laser beam has a Gaussian distribution, into a flat-top beam. A temperature profile of the laser beam is also Gaussian. The second beam shaping optics 1522 convert the flat-top circular beam out of the flat-top optics 1520 to a line beam 1524 having an oval-shaped cross section, as shown in
In the example shown in
The laser 1504 may be operated in a pulse mode or a continuous wave (CW) mode. During the pulse mode, the output of the beam shaping optics 1512 may be provided directly to a beam size adjustment device 1526. During the pulse mode, the RTP controller 1510 may control a pulse rate of the laser beam, such that pulse duration is in a pico-second or a nanosecond range. An acousto-optic modulator 1523 may be included when the laser 1504 is being operated in the CW mode. The acousto-optic modulator 1523 may be controlled by the RTP controller 1510. In one embodiment, the RTP controller 1510 generates a RF control signal, which is provided to the acousto-optic modulator 1523. The RF control signal is provided to control a change in a refractive index of a crystal of the acousto-optic modulator 1523. The refractive index of the crystal changes based on a frequency of the RF control signal. The laser beam provided from the beam shaping optics 1512 to the acousto-optic modulator 1523 is deflected by the crystal based on a frequency of the RF signal. The crystal performs as a laser shutter that permits or prevents passage of the laser beam to the beam size adjustment device 1526, the mirror 1514 and/or the polygon scanner 1516. In one embodiment, the RTP controller 1510 controls the frequency of the RF control signal, such that the continuous wave laser beam out of the beam shaping optics 1512 is effectively pulsed (or modulated) by the acousto-optic modulator 1523. The laser beam is pulsed, such that a period of each pulse is in a micro-second or a millisecond range. As a result, use of the acousto-optic modulator 1523 allows for pulsed laser beam generation having longer duration pulses for increased heating per pulse.
The beam size adjustment device 1526 may be disposed between the beam shaping optics 1512 and the mirror 1514 and/or the polygon scanner 1516. The beam size adjustment device 1526 may adjust a size of the line beam to be greater than a diameter of the substrate 112. The beam size adjustment device 1526 may be motorized and include a beam expander 1527.
The RTP controller 1510, the mirror 1514 and/or the polygon scanner 1516 may operate as a uni-dimensional scanning system. The mirror 1514 and/or the polygon scanner 1516 may be rotated to move the laser/line beam 1524 across the surface of the substrate 112 in, for example, a first (or X) direction. The controller 1508 and/or the RTP controller 1510 may rotate the mirror 1514 and/or the polygon scanner 1516 via a corresponding motor, as described above to scan across the surface of the substrate 112. In each position of the line beam on the surface of the substrate, the line beam heats portions of the dies of the substrate 112 in a y-direction. One or more pulses may be generated at each position of the line beam. The line beam may be cycled across the surface multiple times to remove a predetermined thickness (or thicknesses) of material from the substrate 112.
The method may begin at 1700. At 1702, a substrate (e.g., the substrate 112 of
At 1706, a surface of the substrate is cleaned. As an example the substrate may include an upper (or top) layer that is disposed on a base layer. The upper layer may include or consist of a metal, a metal oxide or a metal nitride. The upper surface of the upper layer may be cleaned.
At 1708, pretreatment is performed including exposing one or more surfaces and/or layers of the substrate that include a metal, a metal oxide or a metal nitride with, for example, molecular oxygen (O2) plasma, ozone (O3), hydrogen peroxide (H2O2), water vapor plasma, hydrogen (H2) plasma, molecular chlorine (Cl2) plasma, hydrazine (N2H4), ammonia (NH3) plasma, and/or other gas. The surface modification may include a non-plasma process, such as flow of chemicals, hydrogen peroxide (H2O2) vapor, water (H2O) vapor, hydrazine (N2H4), and/or other chemical reactant. In another embodiment, the surface modification includes a plasma process, such as flow of molecular oxygen (O2) plasma, molecular hydrogen (H2) plasma, an ammonia (NH3) plasma, a water (H2O) plasma, and/or other plasma. Operation 1708 may be performed to convert a metal to a metal oxide or a metal halide. As an example, this may include supplying O2 plasma to convert TiN (Ti3+) to TiO2 (Ti4+), which may occur at room temperature or at other temperatures. This operation may be performed for de-chlorination and surface activation. As an example, a plasma gas mixture including hydrogen (H2) gas or ammonia (NH3) gas species is supplied to the processing chamber. In one embodiment, surface modification is performed without plasma, but by using gases having a preselected chemistry.
At 1709, the substrate is optionally preheated. This may include increasing temperature of the substrate support (or a plate thereof) and/or temperature within the corresponding processing chamber as described above. As an example, the temperature of the substrate, substrate support, and/or interior of the processing chamber may be increased to a predetermined temperature (e.g., 200° C.). In an embodiment, operation 1709 is not performed and the substrate is maintained at a room temperature. In one embodiment, the temperature of the substrate, substrate support and/or interior of the processing chamber are at temperatures greater than or equal to a room temperature and less than a boiling point of a complex metal to be formed as a result of performing the following operation 1710.
At 1710, atomistic adsorption is performed including introduction of one or more reactive free ligands, such as hexafluroacetylacetone Hhfac and/or acetylacetone Hacac, and/or introduction of one or more other organic gases, vapors and/or reactants to be adsorbed into the substrate. The metal-free ligand may include molecular chlorine (Cl2), ethanol (EtOH), and/or other organic vapor. In an embodiment, the metal-free ligand is Cl2. This operation includes converting one or more upper and/or outer surfaces/layers of the substrate that was modified at 1708 into a layer having a metal complex. Operation 1710 may occur at temperatures, for example, greater than or equal to a room (or ambient) temperature and less than a boiling point of the metal complex. The one or more ligands introduced may be selected based on the metal, metal oxide, and/or metal nitride being etched, the pre-treatment performed, the temperature of the surface/layer being etched, the energy level used for etching, etc. This enables precise and highly selective etching including selective etch depths and etch rates for surfaces having different metals and/or metal compounds.
At 1712, the corresponding process chamber is purged of gases. At 1714, extended (or long) pulsed or non-pulsed thermal annealing is performed. This may include, for example, heating the substrate support and/or using flash lamps, a laser or other suitable lamps (e.g., infrared lamps) capable of providing extended length heating pulses. The substrate support may be heated, for example, to temperatures between 250° C. to 400° C. Cl2 may not react with a surface of the substrate at temperatures greater than 400° C. The extended length heating pulses are longer than a predetermined length, for example, the pulses may each be longer than 20 ms when a flash lamp is used and longer than 20 ps when a laser is used. The heating may be provided for a predetermined period of time and then removed. In one embodiment, heating pulses are not provided and the substrate support and/or the processing chamber is heated.
At least operations 1708-1715 may be iteratively performed including modulating surface or upper portion temperatures of the substrate. Thermal annealing is performed at 1714 for desorption/removal purposes. Temperatures may be increased to evaporate certain molecules.
No inorganic salt or additional metal complex is produced when performing the above stated operations. An additional metal complex can be produced when, for example, a metal precursor is introduced. The above operations do not include introduction of a metal precursor. Incomplete organic residual may be cleaned easily by introducing hydrogen plasma or oxygen plasma in a surface refresh operation, such as at 1715.
At 1715, the surface of the substrate may be refreshed by purging the process chamber with a purge gas (e.g., argon (Ar) gas) to perform ion bombardment and remove the modified portion(s) of the substrate. In one embodiment, the processing chamber is purged between one or more consecutive pairs of provided rapid thermal pulses. In an embodiment, the gases are purged from the processing chamber between each consecutive pair of pulses. This enables performance of multiple plasma and/or gas phase processes within the processing chamber. In an embodiment, substrate support cooling is provided during and/or subsequent to pulsed rapid thermal annealing to aid in maintaining temperatures of the base and/or bulk of the substrate during pulsed rapid thermal annealing and to aid in rapid cooling of the substrate subsequent to performing pulsed rapid thermal annealing.
At 1716, the controller 180 or 208 determines whether N cycles have been completed, where N is an integer greater than or equal to 1. If N cycles have been completed, operation 1718 is performed, otherwise operation 1708 is performed. At 1718, the controller 180 or 210 may optionally perform a second (or post) annealing operation. At 1719, the controller 180 or 210 may determine, for a current die, whether to perform another process and/or whether to change and/or reiterate a current process. If another process is to be performed, operation 1704 may be performed, otherwise operation 1720 may be performed when a laser and a lens circuit is utilized as in the embodiment of
At 1724, the controller 208 moves the mirrors 214, 216 to change an image plane position of a laser beam to be over a different die of the substrate 112. As an example, a 2 cm×2 cm laser beam may be moved from being over a first die to being over a second die. The described method may be iteratively performed to scan the laser beam over tens to hundreds of dies on the substrate. Movement of the mirrors 214, 216 may be synchronized with a pulsing repetition rate of the laser 204 to provide one or more shots per die.
The above-described operations are meant to be illustrative examples. The operations may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods or in a different order depending upon the application. Also, any of the operations may not be performed or skipped depending on the implementation and/or sequence of events.
The above-described method provides highly selective ALE with high throughput with improved ALE thickness control over that provided during plasma etching. The examples include introducing CL2, which attacks TiO2 and does not react with TiN, which provides a self-limiting process. The introduction of O2 plasma to convert Ti to an oxidized state is an effective and fast process and the introduction of Cl2 to remove TiO2 leaves no residual. Also, Cl2 does not react with SiO2.
A fill portion of a via can contribute most of the resistance in a back-end-of-line (BEOL) process. To reduce this resistance, a bottom portion of the via may be removed using the following method of
The method may begin at 1800. At 1802, a substrate (e.g., the substrate 112 of
At 1806, a surface of the substrate is cleaned. As an example the substrate may include an upper (or top) layer that is disposed on a base layer. The upper layer may include or consist of a metal, a metal oxide or a metal nitride. The upper surface of the upper layer may be cleaned.
At 1808, pretreatment is performed including exposing one or more surfaces and/or layers of the substrate that include a metal, a metal oxide or a metal nitride with, for example, molecular oxygen (O2) plasma, ozone (O3), hydrogen peroxide (H2O2), water vapor plasma, hydrogen (H2) plasma, molecular chlorine (Cl2) plasma, hydrazine (N2H4), ammonia (NH3) plasma, and/or other gas. In one embodiment, O2 pmasa is introduced. In another embodiment H2 plasma is introduced. The surface modification may include a non-plasma process, such as flow of chemicals, hydrogen peroxide (H2O2) vapor, water (H2O) vapor, hydrazine (N2H4), and/or other chemical reactant. In another embodiment, the surface modification includes a plasma process, such as flow of molecular oxygen (O2) plasma, molecular hydrogen (H2) plasma, an ammonia (NH3) plasma, a water (H2O) plasma, and/or other plasma.
During this operation, plasma chamber pressure and/or pressure of plasma included therein is maintained at a low pressure (e.g., a pressure less than a predetermined pressure). A bias power (bias current and/or voltage) is supplied via, for example, the RF generator 120-2 of
During operation 1808, a portion 1920 of the top layer 1908 that are in contact with the top surface of the intermediate layer 1906 and a portion 1922 of the top surface of the conductive underlayer 1904 that is in the hole 1910 is modified for removal during operation 1814. Sidewall portion 1930 of the top layer 1908 remains in the hole 1910. A result of operations 1808 and 1814 is shown in
During operation 1808 and in an embodiment, an 02 plasma may be provided, with bias power supplied to the substrate and a low process chamber pressure. Oxidizing ions from the plasma may be extracted and the substrate may be biased to a sufficiently high voltage to provide directional bombardment of the oxidizing ions. In another embodiment, hydrogen peroxide (H2O2) and/or ozone (O3) is provided at low pressure. O2 may provide an increased etch rate as compared to O3. In another embodiment, the provided plasma, the process chamber, and/or the supplied one or more gases are at a low pressure. In one embodiment, bias power is not provided. In an embodiment, the bottom portion 1922 is oxidized or hydrogenated and the sidewall portion 1930 is not oxidized or hydrogenated. The oxidized or hydrogenated areas are reactive towards Cl2 and/or metal free ligands and are able to be converted to a volatile species to be removed by rapid thermal pulsing.
At 1809, the substrate is optionally preheated. This may include increasing temperature of the substrate support and/or temperature within the corresponding processing chamber as described above. As an example, the temperature of the substrate, substrate support, and/or interior of the processing chamber may be increased to a predetermined temperature (e.g., 200° C.). In an embodiment, operation 1809 is not performed and the substrate is maintained at a room temperature. In one embodiment, the temperature of the substrate, substrate support and/or interior of the processing chamber are at temperatures greater than or equal to a room temperature and less than a boiling point of a complex metal to be formed as a result of performing the following operation 1810.
At 1810, atomistic adsorption is performed including introduction of one or more reactive free ligands, such as hexafluroacetylacetone Hhfac and/or acetylacetone Hacac, and/or introduction of one or more other organic gases, vapors and/or reactants to be adsorbed into the substrate. The metal-free ligand may include molecular chlorine (Cl2), ethanol (EtOH), and/or other organic vapor. In an embodiment, the metal-free ligand is Cl2. This operation includes converting one or more upper and/or outer surfaces/layers of the substrate that was modified at 1808 into a layer having a metal complex. Operation 1810 may occur at temperatures, for example, greater than or equal to a room (or ambient) temperature and less than a boiling point of the metal complex. The one or more ligands introduced may be selected based on the metal, metal oxide, and/or metal nitride being etched, the pre-treatment performed, the temperature of the surface/layer being etched, the energy level used for etching, etc. This enables precise and highly selective etching away of the portions 1920, 1922.
At 1812, the corresponding process chamber is purged of gases. At 1814, pulsed rapid thermal annealing is performed using, for example, flash lamps, a laser or other suitable lamps (e.g., infrared lamps) capable of being rapidly pulsed as described herein. In an embodiment, flash lamps are utilized providing a predetermined amount of thermal energy (e.g., 7 Joules (J) or 11 J). In another embodiment, pulsed laser is utilized.
At least operations 1808-1815 may be iteratively performed including modulating surface or upper portion temperatures of the substrate. The temperature of the surface or upper portion may be modulated multiple times in a single second. Pulsed rapid thermal annealing is performed at 1814 for desorption/removal purposes. This may include generating one or more thermal energy pulses to heat the modified portion of the substrate. Temperatures may be increased to evaporate certain molecules. Rapid thermal pulsing enables a clean reaction at surface of substrate, which frees the metal complex from the substrate.
No inorganic salt or additional metal complex is produced when performing the above stated operations. An additional metal complex can be produced when, for example, a metal precursor is introduced. The above operations do not include introduction of a metal precursor. Incomplete organic residual may be cleaned easily by introducing hydrogen plasma or oxygen plasma in a surface refresh operation, such as at 1815.
A base and/or bulk of the substrate is maintained at or below a predetermined temperature (e.g., less than or equal to 20° C.) during operation 1814. RTP enables one processing chamber configuration to be used with high throughput. Multiple processing operations may be performed in the single processing chamber. As another example, each of the pulses may be 0.1 millisecond (ms) in length and a temperature of a surface and/or a portion of the substrate may be increased up to 1000° C.
In some examples, each of the flash lamp pulses provides 5 J/cm2 (i.e., energy per unit area of the substrate) to 80 J/cm2. In some examples, each of the laser pulses provides 5 mJ/cm2 to 80 mJ/cm2. In some examples, the annealing is performed during a predetermined period in a range from 0.1 ms to 20 ms. In one embodiment, the flash lamp is used with pulse durations of 1 ms or the laser is used with pulse durations of 1 picosecond (ps) to heat the surface or upper portion of the substrate from an initial temperature to greater than 500° C. and then cooled back down to the initial temperature in less than 1 second (s).
Operations 1808, 1810, 1814 allow for controllable atom by atom removal of selective portions of a surface and/or upper layer of the substrate that was modified during operations 1808 and 1810. The rapid heating performed at 1814 provides an isotropic reaction without use of plasma. In addition, the claimed heating allows for rapid cool down, which also prevents thermal budget issues.
At 1815, the surface of the substrate may be refreshed by purging the process chamber with a purge gas (e.g., argon (Ar) gas) to perform ion bombardment and remove the modified portion(s) of the substrate. In one embodiment, the processing chamber is purged between one or more consecutive pairs of provided rapid thermal pulses. In an embodiment, the gases are purged from the processing chamber between each consecutive pair of pulses. This enables performance of multiple plasma and/or gas phase processes within the processing chamber. In an embodiment, substrate support cooling is provided during and/or subsequent to pulsed rapid thermal annealing to aid in maintaining temperatures of the base and/or bulk of the substrate during pulsed rapid thermal annealing and to aid in rapid cooling of the substrate subsequent to performing pulsed rapid thermal annealing.
At 1816, the controller 180 or 208 and/or rapid thermal pulse controller 182 or 210 determines whether N cycles have been completed, where N is an integer greater than or equal to 1. If N cycles have been completed, operation 1818 is performed, otherwise operation 1808 is performed. At 1818, the controller 180 or 210 may optionally perform a second (or post) annealing operation. At 1819, the controller 180 or 210 may determine, for a current die, whether to perform another process and/or whether to change and/or reiterate a current process. If another process is to be performed, operation 1804 may be performed, otherwise operation 1820 may be performed when a laser and a lens circuit is utilized as in the embodiment of
At 1824, the controller 208 moves the mirrors 214, 216 to change an image plane position of a laser beam to be over a different die of the substrate 112. As an example, a 2 cm×2 cm laser beam may be moved from being over a first die to being over a second die. The described method may be iteratively performed to scan the laser beam over tens to hundreds of dies on the substrate. Movement of the mirrors 214, 216 may be synchronized with a pulsing repetition rate of the laser 204 to provide one or more shots per die.
The above-described operations are meant to be illustrative examples. The operations may be performed sequentially, synchronously, simultaneously, continuously, during overlapping time periods or in a different order depending upon the application. Also, any of the operations may not be performed or skipped depending on the implementation and/or sequence of events.
The above-described method of
The method of
The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.
Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”
In some implementations, a controller is part of a system, which may be part of the above-described examples. Such systems can comprise semiconductor processing equipment, including a processing tool or tools, chamber or chambers, a platform or platforms for processing, and/or specific processing components (a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling their operation before, during, and after processing of a semiconductor wafer or substrate. The electronics may be referred to as the “controller,” which may control various components or subparts of the system or systems. The controller, depending on the processing requirements and/or the type of system, may be programmed to control any of the processes disclosed herein, including the delivery of processing gases, temperature settings (e.g., heating and/or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, positional and operation settings, wafer transfers into and out of a tool and other transfer tools and/or load locks connected to or interfaced with a specific system.
Broadly speaking, the controller may be defined as electronics having various integrated circuits, logic, memory, and/or software that receive instructions, issue instructions, control operation, enable cleaning operations, enable endpoint measurements, and the like. The integrated circuits may include chips in the form of firmware that store program instructions, digital signal processors (DSPs), chips defined as application specific integrated circuits (ASICs), and/or one or more microprocessors, or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions communicated to the controller in the form of various individual settings (or program files), defining operational parameters for carrying out a particular process on or for a semiconductor wafer or to a system. The operational parameters may, in some embodiments, be part of a recipe defined by process engineers to accomplish one or more processing steps during the fabrication of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and/or dies of a wafer.
The controller, in some implementations, may be a part of or coupled to a computer that is integrated with the system, coupled to the system, otherwise networked to the system, or a combination thereof. For example, the controller may be in the “cloud” or all or a part of a fab host computer system, which can allow for remote access of the wafer processing. The computer may enable remote access to the system to monitor current progress of fabrication operations, examine a history of past fabrication operations, examine trends or performance metrics from a plurality of fabrication operations, to change parameters of current processing, to set processing steps to follow a current processing, or to start a new process. In some examples, a remote computer (e.g. a server) can provide process recipes to a system over a network, which may include a local network or the Internet. The remote computer may include a user interface that enables entry or programming of parameters and/or settings, which are then communicated to the system from the remote computer. In some examples, the controller receives instructions in the form of data, which specify parameters for each of the processing steps to be performed during one or more operations. It should be understood that the parameters may be specific to the type of process to be performed and the type of tool that the controller is configured to interface with or control. Thus as described above, the controller may be distributed, such as by comprising one or more discrete controllers that are networked together and working towards a common purpose, such as the processes and controls described herein. An example of a distributed controller for such purposes would be one or more integrated circuits on a chamber in communication with one or more integrated circuits located remotely (such as at the platform level or as part of a remote computer) that combine to control a process on the chamber.
Without limitation, example systems may include a plasma etch chamber or module, a deposition chamber or module, a spin-rinse chamber or module, a metal plating chamber or module, a clean chamber or module, a bevel edge etch chamber or module, a physical vapor deposition (PVD) chamber or module, a chemical vapor deposition (CVD) chamber or module, an atomic layer deposition (ALD) chamber or module, an atomic layer etch (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and any other semiconductor processing systems that may be associated or used in the fabrication and/or manufacturing of semiconductor wafers.
As noted above, depending on the process step or steps to be performed by the tool, the controller might communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout a factory, a main computer, another controller, or tools used in material transport that bring containers of wafers to and from tool locations and/or load ports in a semiconductor manufacturing factory.
The present disclosure claims the benefit of U.S. Provisional Patent Application Nos. 62/832,932, filed on Apr. 12, 2019 and 62/792,519, filed on Jan. 15, 2019. The entire disclosures of the applications referenced above are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/US2020/012518 | 1/7/2020 | WO | 00 |
Number | Date | Country | |
---|---|---|---|
62832932 | Apr 2019 | US | |
62792519 | Jan 2019 | US |