Method for increasing chemical contrast between exposed and unexposed areas of a metal containing photoresist

Abstract

The various embodiments described herein relate to methods, apparatus, and systems for baking a metal-containing substrate on a semiconductor substrate in the presence of a reactive gas species. For example, the method may include receiving the substrate in a processing chamber, the substrate including a photoresist layer on top, wherein the photoresist layer includes a metal-containing photoresist material; flowing a reactive gas species from a gas source, through a gas delivery line, and into the processing chamber; exposing the substrate to the reactive gas species in the processing chamber; and baking the photoresist layer when the substrate is exposed to the reactive gas species.

Description

[Technical Field]

[0001] This disclosure generally relates to the field of semiconductor processing. In a particular embodiment, this disclosure relates to a process and apparatus for processing photoresist to form a patterned mask in the context of photolithography and film development. [Previous Technology]

[0002] As semiconductor processing continues to advance, feature sizes are constantly shrinking, necessitating new processing methods. One area under development is patterning, for example, using photoresist materials that are patterned by exposure to radiation.

[0003] The prior art description provided herein is for the purpose of generally presenting the background of this disclosure. The work of the inventors listed in this case, the scope of the prior art paragraphs herein, and the embodiments that may not be worthy of being considered prior art at the time of application are not intended or implied as prior art against the content of this disclosure. [Summary of the Invention]

[0004] The various embodiments herein relate to methods, apparatus, and systems for baking a photoresist layer located on a substrate. In one example of the disclosed embodiments, a method for baking a photoresist layer located on a substrate is provided, the method comprising: receiving the substrate in a processing chamber, the substrate including the photoresist layer located above it, wherein the photoresist layer includes a metal-containing photoresist material; flowing a reactive gas species from a gas source, through a gas delivery line, and into the processing chamber; exposing the substrate to the reactive gas species in the processing chamber; and baking the photoresist layer while the substrate is exposed to the reactive gas species.

[0005] In various embodiments, the photoresist layer comprises an extreme ultraviolet (EUV) photoresist material. In some embodiments, the reactive gas species comprises a gas selected from the group consisting of water, hydrogen, oxygen, ozone, hydrogen peroxide, carbon monoxide, carbon dioxide, ammonia, nitrous oxide, nitric oxide, alcohols, acetone, formic acid, oxalic acid, pyridine, carboxylic acids, amines, and combinations thereof. In some cases, the reactive gas species may include water. In these or other cases, the reactive gas species may include hydrogen. In these or other cases, the reactive gas species may include oxygen. In these or other cases, the reactive gas species may include ozone. In these or other cases, the reactive gas species may include hydrogen peroxide. In these or other cases, the reactive gas species may include carbon monoxide. In these or other cases, the reactive gas species may include carbon dioxide. In these or other cases, the reactive gas species may include ammonia. In some such cases, baking the photoresist occurs after the photoresist has been exposed to EUV radiation for patterning, and wherein one of the following conditions is met: (i) when baking the photoresist, the processing chamber is maintained at atmospheric pressure and the ammonia system is provided at a concentration between about 0.001 and 5% (by volume); or (ii) when baking the photoresist, the processing chamber is maintained at subatmospheric pressure and the ammonia system is provided at a partial pressure between about 1 and 100 mTorr. In these or other cases, the reactive gas species may include nitrous oxide and / or nitric oxide. In these or other cases, the reactive gas species may include alcohols. In these or other cases, the reactive gas species may include acetone. In these or other cases, the reactive gas species may include formic acid. In these or other cases, the reactive gas species may include oxalic acid. In these or other cases, the reactive gas species may include carboxylic acids. In these or other cases, the reactive gas species may include amines. In some cases, exemplary amines may include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, and / or triethylamine. In various embodiments, the reactive gas species may be oxidizing. In these or other cases, the reactive gas species may be polar.

[0006] In some embodiments, exposing the substrate to the reactive gas species can promote cross-linking within the photoresist layer. In these or other embodiments, exposing the substrate to the reactive gas species can promote the removal of low molecular weight species in the photoresist layer. For example, each molecule of the low molecular weight species may include 0, 1, or 2 metal atoms. In some embodiments, exposing the substrate to the reactive gas species can oxidize metal hydride species in the photoresist layer into metal hydroxide species.

[0007] In some embodiments, the method may further include applying a vacuum to the processing chamber while the photoresist layer is being baked. In these or other embodiments, the method may further include controlling the water concentration in the processing chamber to maintain it within a target water concentration range while the photoresist layer is being baked. Similarly, the method may include controlling the oxygen concentration in the processing chamber to maintain it within a target oxygen concentration range while the photoresist layer is being baked. In some embodiments, the processing chamber may be maintained at or below atmospheric pressure while the photoresist layer is being baked. For example, in some cases, the processing chamber may be maintained below atmospheric pressure while the photoresist layer is being baked.

[0008] When baking the photoresist layer, the temperature of the support on which the substrate is disposed can be controlled. For example, in some embodiments, the method may further include increasing the temperature of a substrate support, wherein the substrate is disposed on the substrate support, when baking the photoresist layer. In these or other embodiments, the method may further include decreasing the temperature of a substrate support, wherein the substrate is disposed on the substrate support, when baking the photoresist layer. In some cases, the method may include controlling the flow of the reactive species into the processing chamber to achieve a target degree of crosslinking. Various types of heat can be provided. In some embodiments, baking the photoresist layer includes heating the substrate on a heating plate. In some embodiments, baking the photoresist layer includes exposing the substrate to infrared radiation and / or ultraviolet radiation. In some embodiments, baking the photoresist layer may include heating the substrate from above. In these or other embodiments, baking the photoresist layer may include heating the substrate from below.

[0009] The methods described herein can be used in various applications. In some cases, the photoresist layer has been applied to the substrate but has not yet been patterned, and the baking is post-application baking (PAB). In other cases, the photoresist layer has been applied to the substrate and patterned by partial exposure to EUV radiation to create exposed and unexposed portions of the photoresist layer, and the baking is post-exposure baking (PEB). In these or other embodiments, the reactive gas species may include polar and oxidizing molecules. For example, the reactive gas species may include hydrogen peroxide.

[0010] In another embodiment disclosed, an apparatus for baking a photoresist layer on a substrate is provided. The apparatus includes: a processing chamber; an inlet for directing a reactive gas species into the processing chamber; an outlet for removing material from the processing chamber; a substrate support located within the processing chamber; a heater configured to heat the substrate by conduction, convection, and / or radiation; and a controller having at least one processor, wherein the at least one processor is configured to control the apparatus to perform any of the methods claimed herein or otherwise described.

[0011] These and other states are further described below with reference to the diagram.

Implementation Method

[0014] Specific embodiments of this disclosure are referenced in detail herein. Examples of these specific embodiments are illustrated in the accompanying drawings. While this disclosure will be described in conjunction with these specific embodiments, it will be understood that this is not intended to limit the disclosure to these specific embodiments. Rather, it is intended to cover all variations, modifications, and equivalents that may be included within the spirit and scope of this disclosure. In the following description, numerous specific details are set forth to provide a thorough understanding of this disclosure. This disclosure may be practiced without some or all of these specific details. In other instances, conventional processing operations have not been described in detail to avoid unnecessarily obscuring this disclosure.

[0015] Thin film patterning in semiconductor processing is often an important step in semiconductor fabrication. Patterning involves photolithography. In conventional photolithography (e.g., 193 nm photolithography), a pattern is printed on a photosensitive photoresist film. By exposing the photoresist to photons in a selected area defined by a photomask, a chemical reaction is induced in the photoresist, generating a chemical contrast that plays an important role in the development step, thereby removing certain portions of the photoresist to form the pattern. Subsequently, the patterned and developed photoresist film can be used as an etching mask to transfer the pattern to an underlying film composed of metals, oxides, etc.

[0016] Advanced technology nodes, including 22 nm, 16 nm, and lower (as defined in the International Semiconductor Technology Roadmap), require continuous improvement in lithography resolution. For example, in the 16 nm node, the width of vias or lines in the damascene structure is typically no more than about 30 nm, which is impossible for a simple 193 nm photolithography system, otherwise it would involve complex multi-patterning schemes.

[0017] Compared to conventional optical lithography methods, extreme ultraviolet (EUV) lithography can expand lithography techniques by shifting to smaller imaging source wavelengths. EUV light sources with wavelengths of approximately 10-20 nm or 11-14 nm (e.g., 13.5 nm wavelength) can be used in leading-edge lithography tools, also known as scanners. EUV radiation is strongly absorbed by various solid and fluid materials (including quartz and water vapor) and atmospheric pressure gases; therefore, EUV scanners operate in a vacuum.

[0018] EUV lithography uses EUV photoresist that can be patterned by EUV light to form a mask used in the underlying etch layer. EUV photoresist can be a polymer-based chemically amplified resist (CAR) manufactured through a liquid-based spin coating technique. An alternative to CAR is a metal oxide-based EUV photoresist (PR) film that can be directly patterned by light. Such PR films can be manufactured by (wet) spin coating techniques, such as those obtained from Inpria, Corvallis, OR, and those described in, for example, U.S. Patent Publications US 2017 / 0102612 and US 2016 / 0116839, at least their disclosures of photo-patternable metal oxide films are incorporated herein by reference; or by dry vapor deposition as described in PCT / US19 / 31618, filed May 9, 2019, entitled "METHODS FOR MAKING EUV PATTERNABLE HARD MASKS," which discloses at least the composition and patterning of directly photopatternable metal oxide films to form EUV photoresist masks, are incorporated herein by reference. These directly photopatternable EUV photoresists can be composed of, or contain, metals with high EUV absorbance, and their organometallic oxides / hydroxides and other derivatives. Following EUV exposure, EUV photons and the resulting secondary electrons can induce chemical reactions, such as the β-hydrogen elimination reaction in SnOx-based photoresists (and photoresists based on other metal oxides), and provide chemical functionality to promote cross-linking and other changes in the photoresist film. These chemical changes can then play an important role in the development step to selectively remove exposed or unexposed areas of the photoresist film, forming the etch mask used for the transfer pattern.

[0019] It should also be understood that although this disclosure relates to lithography patterning techniques and materials using EUV lithography as an example, it can also be applied to other next-generation lithography techniques. Besides EUV, which currently includes the standard 13.5 nm EUV wavelength, the most relevant radiation sources for this lithography are DUV (deep UV), which generally refers to excimer laser sources using 248 nm or 193 nm; X-rays, which in turn include EUV in the lower energy range of the X-ray range; and electron beams, which can cover a wide energy range. These specific methods can depend on the specific materials and applications used in the semiconductor substrate and the final semiconductor device. Therefore, the methods described in this application are merely exemplary methods and materials that can be used in this technology.

[0020] Photolithography typically involves one or more baking steps to promote the chemical reactions required to create chemical contrast between exposed and unexposed areas of the photoresist. For high-volume manufacturing (HVM), these baking steps are typically performed on a track, where the wafer is baked on a heated plate at a preset temperature in ambient air (or, in some cases, an N2 gas flow). Careful control of the baking environment during these baking steps, and the introduction of additional reactive gas components from the environment, can help to further reduce dosage requirements and / or improve pattern fidelity.

[0021] This disclosure describes a novel baking strategy involving careful control of the baking environment, the introduction of reactive gases, and, in some cases, careful control of the roasting rate of the baking temperature. This strategy can be particularly useful for metal oxide-based EUV photoresists (PRs). Examples of useful reactive gases include water, hydrogen, oxygen, ozone, hydrogen peroxide, carbon monoxide, carbon dioxide, ammonia, nitrous oxide, nitric oxide, methylamine, dimethylamine, alcohols, acetone, formic acid, oxalic acid chloride, carboxylic acids, other amines, and any substituted forms of these materials. The reactive gas system is provided in gaseous form and can be vaporized before being delivered to the reaction chamber. Various exemplary gas systems are further described below.

[0022] While this disclosure is not limited to any particular theory or operational mechanism, it should be understood that these reactive gas molecules can potentially accelerate the crosslinking behavior of the metal oxide-based EUV photoresist in the EUV-exposed region (in this example, the region retained to form a mask after the development of the patterned film) via oxidation, coordination, or acid / base chemistry, while having a limited impact on the crosslinking in the unexposed region. Alternatively or additionally, in some cases, the reactive gas molecules can promote the removal of volatile species from the metal oxide-based EUV photoresist, thereby further improving the stability of the photoresist.

[0023] Figure 1 is a flowchart presented according to various embodiments. At operation 101, photoresist is deposited on a substrate. The substrate on which the photoresist is deposited typically includes an underlying material that will eventually be etched after the photoresist is patterned / developed. In various embodiments, the substrate on which the photoresist is deposited may have an exposed layer of amorphous carbon, spin-on carbon (SoC), spin-on glass (SoG), silicon oxide, silicon nitride, silicon nitride, silicon carbide, silicon carbide, etc. In many cases, the exposed layer is an ashable hard mask (AHM). The photoresist deposited in operation 101 is an EUV photoresist based on metal oxides. The deposition may be performed by wet spin-on technology or dry vapor-based technology (e.g., chemical vapor deposition (CVD) and / or atomic layer deposition (ALD)), both of which may be driven by thermal energy, plasma energy, or both. Next, at operation 103, the substrate is exposed to the heat of the first baking step, often referred to as post-application bake (PAB). At operation 105, the substrate is exposed to EUV radiation to pattern the photoresist, thereby forming exposed and unexposed areas of the photoresist. Next, at operation 107, the substrate is exposed to the heat of the second baking step, often referred to as post-exposure bake (PEB). Next, at operation 109, the photoresist is developed to selectively remove the unexposed areas. In various embodiments herein, the atmosphere to which the substrate is exposed can be controlled during the PAB of operation 103 and / or the PEB of operation 107. For example, the substrate can be exposed to one or more reactive gases during these steps. Each baking step is further described below. 1. Post-application bake (PAB)

[0024] Post-baking is performed after the photoresist is deposited on the substrate and before the photoresist is exposed to EUV radiation used for patterning. See operation 103 in Figure 1. PAB can be performed to remove excess solvent (e.g., in the case of photoresist deposited by spin coating), remove other low molecular weight or other volatile species, and promote the desired degree of crosslinking within the photoresist. These features are operated to improve the stability of the photoresist. For example, by removing unbonded or only loosely bonded low molecular weight or other volatile species within the photoresist, outgassing of metal-containing molecules can be reduced to an acceptable level (e.g., <1E10 molecules / (cm2*month)). Removing these materials is advantageous because they may otherwise contaminate downstream processes, equipment, and the substrate. Crosslinking achieved during PAB also improves the stability of the photoresist; however, excessive crosslinking may lead to increased linewidth roughness. Therefore, crosslinking can be controlled to a desired level during PAB.

[0025] In various embodiments herein, the substrate may be exposed to a reactive gas during PAB. This reactive gas facilitates the removal of low molecular weight or other volatile species. In various embodiments, the low molecular weight species removed during PAB may have 0, 1, or 2 metal atoms. In some cases, the removed low molecular weight species may include bimetallic species. Molecules having three or more metal atoms typically have relatively high molecular weights and are relatively non-volatile, and may substantially remain in the photoresist during PAB. In addition to removing low molecular weight species, the reactive gas promotes a desired degree of crosslinking within the photoresist. Due to the effects of these characteristics, the use of a reactive gas during PAB helps stabilize the photoresist.

[0026] Exemplary processing apparatus and reactive gas systems are provided below. In various embodiments, the substrate may be exposed to any one or more of these reactive gases during PAB. In a particular example, the substrate may be exposed to a processing atmosphere accompanied by an inert gas during PAB, the processing atmosphere having a controlled oxygen and / or moisture (e.g., water vapor) content. In some embodiments, suitable gas sensors and feedback mechanisms may be used to ensure that the composition of the processing atmosphere is controlled within a desired range.

[0027] In various embodiments, one or more processing conditions can be controlled during PAB as follows: The substrate can be heated to a high temperature between about 100-170°C, and in some cases, for example, between about 100-130°C. The pressure can be maintained between about 0.1-760 Torr, and in some cases, for example, between about 0.1-1 Torr. The substrate can be exposed to this high temperature for a duration between about 1-10 minutes, for example, between about 2-5 minutes. An inert gas can be flowed into the processing chamber at a rate between about 10-10,000 sccm. In a particular example, the oxygen (e.g., O2) concentration in the processing chamber can be controlled during PAB. In these or other embodiments, the water (e.g., H2O vapor) concentration can be controlled during PAB.

[0028] In some embodiments, PAB may be omitted. When photoresist is deposited using a dry vapor-based technique rather than a wet spin coating technique, PAB may be unnecessary, for example, because there is no need to remove excess solvent used to deposit the photoresist. However, even when photoresist is deposited using a dry vapor-based technique, performing PAB can help promote the desired degree of crosslinking and remove low molecular weight or other volatile species, which may be a greater concern for dry vapor-based deposition techniques compared to wet spin coating. In some embodiments, PAB may be a conventional PAB. In other words, PAB can be performed without exposing the substrate to reactive gas species and / or in an uncontrolled atmosphere. In such embodiments, the substrate may be exposed to reactive gas species during post-exposure baking, as further described below. 2. Post-exposure baking (PEB)

[0029] Post-exposure baking is performed after the photoresist is exposed to EUV radiation used for patterning and before the photoresist is developed to remove the unexposed portions of the photoresist. See operation 107 in Figure 1. PEB can be performed for several purposes, such as: 1) to drive the complete evaporation of organic fragments generated during EUV exposure; 2) to oxidize metal hydride species (other products from the β-hydrogen elimination reaction during EUV exposure) into metal hydroxides; and 3) to promote crosslinking between adjacent OH groups and form a crosslinked metal oxide network structure.

[0030] The baking temperature is carefully selected to achieve optimal EUV lithography performance. Too low a PEB temperature will result in incomplete removal of organic fragments and insufficient crosslinking, thus resulting in less chemical contrast for development at a given dose. Too high a PEB temperature will also have adverse effects, including severe oxidation and film shrinkage in unexposed areas (in this example, which would be removed by development of the patterned film to form a mask), and undesirable interdiffusion at the interface between the PR and the underlayer (UL; typically spin-coated carbon material), both of which lead to reduced chemical contrast and increased defect density (due to insoluble scum). Using baking temperature and baking time as the only adjustable parameters (knob) often severely limits tunability and process window.

[0031] As described herein, careful control of the baking environment and the introduction of reactive gas species during PEB processing provides additional chemical modifiers to fine-tune the crosslinking process. For example, due to the reduction of alkyl groups and the formation of hydride / hydroxide components, the exposed area tends to be more polar than the unexposed area. Therefore, the presence of polar, oxidizing molecules such as H2O2 during the baking step can promote the oxidation of metal hydrides in the exposed area. Other gases, such as those described below in the Reactive Gases section, can also alter the kinetics of hydride oxidation and crosslinking reactions with hydroxides through oxidation, acid / base chemistry, coordination chemistry, and combinations thereof. The reactive gases can be provided in a controlled atmosphere, for example using any of the equipment described in the Baking Equipment section below. The reactive gases can be provided in conjunction with non-reactive gases such as N2, Ar, He, Ne, Kr, Xe, etc. In some cases, air or clean dry air can be provided in this atmosphere during PEB.

[0032] The ability to tune the kinetics of crosslinking behavior in metal oxide-based EUV photoresist materials provides a wider process margin, which allows for further optimization of lithography performance by minimizing cross-diffusion and other associated defect formation mechanisms. For example, if the reactive gas can be efficiently reduced to lower the baking temperature requirement, concerns about cross-diffusion at the PR / UL interface can be mitigated, which will help reduce defects.

[0033] In some embodiments, one or more processing conditions may be controlled during PEB as follows: The substrate may be heated to a high temperature between about 100-250°C, and in some cases, for example, between about 120-200°C. The pressure may be maintained between about 0.1-760 Torr, and in some cases, for example, between about 0.1-1 Torr. The substrate may be exposed to this high temperature for a duration between about 1-10 minutes, for example, between about 2-5 minutes. An inert gas may be flowed into the processing chamber at a rate between about 10-10,000 sccm. In a particular example, the oxygen (e.g., O2) concentration in the processing chamber may be controlled during PEB. In these or other embodiments, the water (e.g., H2O vapor) concentration may be controlled during PEB.

[0034] In certain embodiments, the substrate may be exposed to ammonia during PEB. In some cases, ammonia may be the only reactive gas present during PEB; however, in other cases, one or more additional reactive gases may be provided alongside ammonia. In some embodiments, ammonia may be provided at a concentration between about 0.001 and 5.0% (by volume), and in some cases between about 0.001 and 0.5% (by volume), at atmospheric pressure or at a partial pressure between about 1 and 100 mTorr (in some cases between 1 and 10 mTorr) when the processing chamber is under vacuum. The duration of PEB (and / or the duration of substrate exposure to ammonia during PEB) may be between about 5 seconds and about 10 minutes, and in some cases between about 5 seconds and 1 minute. After the substrate is exposed to ammonia, the processing chamber may be purged with an inert gas. In various embodiments, the duration of inert gas purging may be the same as or longer than the duration of substrate exposure to ammonia. These steps promote alkaline catalysis of M-OH condensation / crosslinking, which leads to the formation of relatively high molecular weight, low-volatility species, resulting in a more stable photoresist film as described above. These steps also strengthen and compact film regions exposed to EUV radiation (or other types of lithography patterning radiation), achieving these effects at lower baking temperatures than otherwise required to achieve the same film properties. In some embodiments, these same reaction conditions may be used during PAB. In some cases, these same reaction conditions may be used during PAB and / or PEB, accompanied by alternative or additional reactive gases as described herein, including but not limited to other volatile amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, pyridine, etc.

[0035] In some embodiments, PEB may be conventional PEB. In other words, PEB can be performed without providing any reactive gas to the substrate and / or in an uncontrolled atmosphere. In this case, one or more reactive gases may be provided to the substrate during PEB. 3. Reactive Gas

[0036] In various embodiments herein, the substrate may be exposed to one or more reactive gases during the photoresist baking operation. As described above, the reactive gases may promote a desired degree of crosslinking, facilitate the removal of low molecular weight or other volatile species, and / or stabilize the photoresist.

[0037] Several different reactive gases can be used. Examples of practical reactive gases include water (H2O), hydrogen (H2), oxygen (O2), ozone (O3), hydrogen peroxide (H2O2), carbon monoxide (CO), carbon dioxide (CO2), ammonia (NH3), nitrous oxide (N2O), nitric oxide (NO), methylamine (CH3NH2), dimethylamine ((CH3)2NH), trimethylamine (N(CH3)3), ethylamine (CH3CH2NH2), diethylamine ((CH₃CH₂)₂NH), triethylamine (N(CH2CH3)3), alcohols (CnH2n+1OH, including but not limited to methanol, ethanol, propanol, and butanol), and acetone (CH₃COCH₂COCH₃). Formic acid (HCOOH), oxalic acid ((COCl)2), carboxylic acid (CnH2n+1COOH), and other small molecule amines (NR1R2R3, where each of R1, R2, and R3 is independently selected from hydrogen, hydroxyl, aliphatic, haloaliphatic, haloheteroaliphatic, heteroaliphatic, aromatic, aliphatic-aromatic, heteroaliphatic-aromatic, or any combination thereof). Substituted forms of these reactive gases may also be used. In some cases, the substrate may be exposed to two or more reactive gases during the photoresist baking process.

[0038] Reactive gases can interact with photoresist via oxidation, coordination, or acid / base chemistry. In some cases where reactive gases are transported during PEB operation, the reactive gases may preferentially interact with photoresist in areas already exposed to EUV radiation. This preferential interaction may be due to chemical changes that occur during EUV exposure (e.g., a reduction in alkyl groups in the photoresist).

[0039] After the substrate is exposed to the reactive gas during PAB and / or PEB, the chamber in which the substrate is processed may be evacuated and / or purged, for example, with an inert gas. In some cases, the duration of inert gas purging may be at least as long as the duration of exposure of the substrate to the reactive gas. 4. Temperature rise and fall

[0040] In some embodiments, the temperature change of the substrate can be controlled at a certain rate during the baking step. In some cases, rapid heating and cooling may cause problems. By controlling the rise or fall of the substrate temperature at a certain rate, problems associated with rapid heating and cooling can be avoided. Furthermore, the rate at which the baking temperature rises and / or falls can be controlled to fine-tune the crosslinking behavior in the photoresist. 5. Baking Equipment

[0041] The baking operations described herein can be performed on various types of processing equipment. In some cases, the processing equipment may have a closed chamber isolated from the surrounding environment. In other cases, the processing equipment may have an open chamber that is not isolated from the surrounding environment. In some cases using an open chamber, the substrate can be processed on a track, which can be operated continuously or discontinuously. Generally, closed chambers provide better control over the processing atmosphere and provide additional safety associated with potentially hazardous reactive chemicals. However, open chambers may be preferred in some cases, for example, in large-scale production and in the use of non-hazardous chemicals.

[0042] The chamber may be equipped with one or more inlets for providing the required treated atmosphere. The required treated atmosphere may include one or more reactive gases as described above. The inlets may then be fluidly connected to a reactive gas source. The reactive gas may flow from the reactive gas source, through a gas delivery line, through the inlets, and into the chamber. If the reactive gas is liquid at the relevant temperature, the reactive gas may be stored as a liquid and then vaporized before being delivered to the gas delivery line / inlet / chamber. In addition, in some embodiments, air and / or inert gases (e.g., N2, Ar, He, Ne, Kr, Xe, etc.) may be provided to the treated atmosphere. These air and / or inert gases may similarly flow from the gas source, through a gas delivery line, through the inlets, and into the chamber. In some cases, the treated atmosphere may be air-free.

[0043] The chamber may also be equipped with one or more outlets for removing material from the chamber. These outlets may be fluidly connected to a vacuum source to allow active removal of gaseous species from the chamber. Vacuum-connected outlets can be used in both closed and open chambers. When used in a closed chamber, the vacuum-connected outlets can be processed at sub-atmospheric pressure. In the case where the processing chamber is an open chamber (not isolated from the surroundings), the outlets can be any path through which gas can passively escape from the chamber.

[0044] As described above, in some embodiments, the atmosphere within the chamber can be controlled during the baking step. In some cases, the concentration of reactive gases (e.g., oxygen, and / or water, and / or any other reactive gases described herein) can be actively controlled during the baking step. In addition to the aforementioned inlet and outlet, the chamber may be further equipped with sensors (e.g., residual gas analyzers, Fourier transform infrared spectroscopy sensors, etc.) to monitor the atmospheric composition within the chamber. These sensors can be used to provide feedback to actively control the composition of the baking atmosphere.

[0045] To bake the photoresist, the chamber is equipped with one or more heating elements configured to heat the substrate. The heating elements can heat the substrate from above and / or from below. The heating elements can heat the front side of the substrate (e.g., where semiconductor devices / structures are formed) and / or the back side of the substrate. Various types of heating elements can be used independently or in combination with each other. Exemplary heating elements may include heated substrate supports (e.g., bases, chucks, etc.) and radiation sources such as infrared and / or ultraviolet lamps.

[0046] In some embodiments, the chamber may be equipped with one or more cooling elements configured to cool the substrate. For example, a substrate support may be configured to cool the substrate. In one embodiment, the substrate support may include cooling channels through which a heat exchange flow system flows to cool the substrate. Other heat exchange hardware may be used as required by a particular application. After a baking operation, the cooling elements can be particularly useful for controlling the rate of substrate cooling.

[0047] The chamber may also be equipped with a temperature sensor to monitor the temperature of the substrate and / or substrate support during the baking operation. In one example, the chamber includes a pyrometer for measuring the temperature of the substrate surface during baking. Temperature measurements from the pyrometer or other temperature sensor can be used as feedback to actively control the substrate temperature during baking.

[0048] Figure 2 is a simplified view of a processing chamber 200 according to one embodiment. In this example, the processing chamber 200 is a closed chamber with a controllable atmosphere. A substrate 201 may be disposed on a substrate support 202, which may also heat and / or cool the substrate. In some cases, alternative or additional heating and cooling elements may be provided. A processing gas system enters the processing chamber 200 through an inlet 203. Material is removed from the processing chamber 200 through an outlet 204, which may be connected to a vacuum source (not shown). The operation of the processing chamber 200 may be controlled by a controller 206, which is discussed further below. In addition, a sensor 205 may be provided, for example, to monitor the temperature and / or atmospheric composition within the processing chamber 200. The readings obtained from the sensor 205 may be used in an active feedback loop via the controller 206.

[0049] The baking chamber therein can be configured in several ways. In some embodiments, the chamber is the same chamber used for depositing photoresist, and / or the same chamber used for exposing photoresist to EUV radiation, and / or the same chamber used for developing photoresist. In some embodiments, the chamber is a dedicated baking chamber and is not used for other processes such as deposition, etching, EUV exposure, or photoresist development. The chamber can be a stand-alone chamber or can be integrated into larger processing tools, such as deposition tools used for depositing photoresist, EUV exposure tools used for exposing photoresist to EUV radiation, and / or developing tools used for developing photoresist. Depending on the requirements of a particular application, the baking chamber can be combined with any one or more of these tools.

[0050] The chamber may also be equipped with a controller. In some embodiments, the controller is part of a system that may be part of the examples described above. Such a system may include a semiconductor processing apparatus that includes one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, airflow systems, etc.). These systems may be integrated with electronic components to control their operation before, during, and after the processing of semiconductor wafers or substrates. The electronic components may be referred to as "controllers" and may control various components or sub-components of one or more systems. Depending on the processing requirements and / or system type, the controller may be programmed to control any of the processes disclosed herein, including the transport 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 transport settings, position and operation settings, and wafer transport in and out of a tool, other transport tools, and / or transport chambers connected to or interconnected with a specific system.

[0051] Broadly speaking, a controller can be defined as an electronic component having various integrated circuits, logic, memory, and / or software to receive instructions, send instructions, control operations, initiate clear operations, initiate endpoint measurements, etc. The integrated circuits may include a chip storing program instructions in firmware, a digital signal processor (DSP), a chip defined as an application-specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers executing program instructions (e.g., software). Program instructions may be instructions communicated to the controller in various independent settings (or program files) to define operating parameters for performing specific processes on, or for, a semiconductor substrate or a system. In some embodiments, the operating parameters may be part of a recipe defined by a process engineer to complete 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.

[0052] In some embodiments, the controller may be part of a computer, or coupled to a computer that is integrated into and coupled to the system, or otherwise networked to the system, or a combination thereof. For example, the controller may reside in the "cloud," or be all or part of the FAB host computer system, allowing remote access to the substrate processing. The computer may enable remote access to the system to monitor the current progress of the processing operation, examine the history of past processing operations, examine trends or performance metrics from multiple processing operations, change parameters of the current processing, set processing steps after the current processing, or start a new processing. In some examples, the remote computer (e.g., a server) may provide processing recipes to the system via a network, which may include a local area network or the Internet. The remote computer may include a user interface that allows input or programming of parameters and / or settings, which are then transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data, which are specified parameters for each processing step to be performed during one or more operations. It should be understood that the parameters may be specific to the type of processing to be executed and the type of tool the controller is configured to connect to or control. Therefore, as described above, the controller may be distributed, for example, by comprising one or more discrete controllers that are networked together and operate for a common purpose (e.g., the processing and control described herein). An example of a controller distributed for this purpose would be one or more integrated circuits located on a chamber that are connected to one or more integrated circuits located at a remote location (e.g., on a platform layer or as part of a remote computer) and combined to control the processing on the chamber.

[0053] Without limitation, exemplary systems may include plasma etching chambers or modules, deposition chambers or modules, spin-clean chambers or modules, metal plating chambers or modules, cleaning chambers or modules, edge etching chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, orbital chambers or modules, or other semiconductor processing systems that may be related to or used in the processing and / or manufacturing of semiconductor wafers.

[0054] As described above, depending on one or more processing steps to be performed by the tool, the controller may be connected to one or more other tool circuits or modules, other tool components, clustered tools, other tool interfaces, adjacent tools, neighboring tools, tools distributed throughout the plant, a mainframe computer, another controller, or tools used in material handling to bring the substrate container into and out of the tool location and / or loading port of the semiconductor manufacturing plant. Conclusion

[0055] A baking strategy for enhancing the EUV lithography performance of metal-containing EUV photoresist was disclosed.

[0056] It should be understood that the examples and embodiments described herein are for illustrative purposes only, and various modifications or variations based on these examples and embodiments are suggested to those skilled in the art. Although various details have been omitted for clarity, various design alternatives may be implemented. Therefore, the examples presented are to be regarded as illustrative rather than restrictive, and this disclosure is not limited to the details given herein, but modifications may be made within the scope of this disclosure. [Simplified Explanation of the Diagram]

[0012] Figure 1 is a flowchart illustrating the photolithography process according to various embodiments.

[0013] Figure 2 is a simplified view of the processing chamber according to certain embodiments.

Claims

1. A method for increasing the chemical contrast between an exposed and unexposed area of ​​a metal-containing photoresist, the method comprising: contacting the metal-containing photoresist with a reactive gas in a processing chamber, wherein the reactive gas comprises an alcohol, a carboxylic acid, an amine, or a combination thereof, wherein the reactive gas is configured to remove low molecular weight species or volatile species to increase the chemical contrast between the exposed and unexposed areas of the metal-containing photoresist for use in dry development.

2. The method of claim 1, wherein the reactive gas comprises an alcohol.

3. As requested in item 1, wherein the reactive gas contains carboxylic acid.

4. As requested in item 1, wherein the reactive gas contains an amine.

5. The method of claim 4, wherein the reactive gas comprises methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, pyridine, or combinations thereof.

6. The method of claim 1, wherein the contact between the metal-containing photoresist and the reactive gas occurs at a temperature between about 100°C and about 250°C.

7. The method of claim 1, wherein contact between the metal-containing photoresist and the reactive gas occurs before development.

8. The method of claim 1, wherein the metal-containing photoresist comprises a photopatterned metal oxide EUV photoresist.

9. The method of claim 8, wherein the optically patterned metal oxide EUV photoresist comprises tin oxide.

10. The method of claim 1, wherein the reactive gas is transported together with an inert gas.

11. The method of claim 1 further comprises: dry developing the metal-containing photoresist after contacting it with the reactive gas.

12. The method of claim 1, wherein the dry development selectively removes the unexposed area relative to the exposed area containing the metal photoresist to form a photoresist mask.

13. The method of claim 1, wherein the reactive gas is transported together with water.

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