Baking method for enhancing lithographic performance of metal-containing resist

Abstract

SOLUTION: Various embodiments herein relate to methods, apparatus, and systems for baking metal-containing on a semiconductor substrate in the presence of a reactive gas species. For example, the method may include: receiving the substrate in a process chamber, the substrate having a photoresist layer thereon, where the photoresist layer includes a metal-containing photoresist material; causing a reactive gas species to flow from a gas source, through a gas delivery line, into the process chamber; and exposing the substrate to the reactive gas species in the process chamber; and baking the photoresist layer while the substrate is exposed to the reactive gas species.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Incorporation by Reference As part of this application, a PCT application is filed simultaneously with this specification. Each application identified in the PCT application filed simultaneously to which this application claims benefit or priority is hereby incorporated by reference into this specification for all purposes in its entirety.

[0002] The present disclosure generally relates to the field of semiconductor processing. In certain aspects, the present disclosure relates to processes and apparatus for photoresist processing related to lithographic patterning and film development for forming a pattern mask.

Background Art

[0003] As semiconductor manufacturing progresses, feature sizes continue to shrink, requiring new processing methods. One area of advancement relates to patterning using photoresist materials that are patterned by exposure to radiation, for example.

[0004] The description of the background art set forth herein is for the purpose of generally presenting the context of the present disclosure. The inventions of the present inventors, as presently claimed, are not expressly or impliedly admitted as prior art to the present disclosure, either in the context of this background art section or in the context of any description of aspects that do not fall within the prior art at the time of filing.

Summary of the Invention

[0005] Various embodiments herein relate to methods, apparatuses, and systems for baking a photoresist layer on a substrate. In one aspect of embodiments of the present disclosure, a method of baking a photoresist layer on a substrate is provided, the method comprising receiving a substrate in a processing chamber, the substrate having a photoresist layer thereon, the photoresist layer including a metal-containing photoresist material, flowing a reactive gas species from a gas source through a gas supply line into the processing chamber, exposing the substrate in the processing chamber to the reactive gas species, and baking the photoresist layer while the substrate is being exposed to the reactive gas species.

[0006] 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, alcohol, acetylacetone, formic acid, oxalyl chloride, pyridine, carboxylic acid, amine, and combinations thereof. In some cases, the reactive gas species may comprise water. In these or other cases, the reactive gas species may comprise hydrogen. In these or other cases, the reactive gas species may comprise oxygen. In these or other cases, the reactive gas species may comprise ozone. In these or other cases, the reactive gas species may comprise hydrogen peroxide. In these or other cases, the reactive gas species may comprise carbon monoxide. In these or other cases, the reactive gas species may comprise carbon dioxide. In these or other cases, the reactive gas species may comprise ammonia. In some such cases, baking of the photoresist occurs after the photoresist is exposed to EUV light for patterning of the photoresist, and any of the following conditions is satisfied. (i) The processing chamber is maintained at atmospheric pressure during baking of the photoresist, and ammonia is provided at a concentration of about 0.001 - 5 (volume)%, and, (ii) The processing chamber is maintained at sub-atmospheric pressure during baking of the photoresist, and ammonia is provided at a partial pressure of about 1 - 100 mTorr. In these or other cases, the reactive gas species may comprise nitrous oxide and / or nitric oxide. In these or other cases, the reactive gas species may comprise alcohol. In these or other cases, the reactive gas species may comprise acetylacetone. In these or other cases, the reactive gas species may comprise formic acid. In these or other cases, the reactive gas species may comprise oxalyl chloride. In these or other cases, the reactive gas species may comprise carboxylic acid. In these or other cases, the reactive gas species may comprise amine. Examples of amines may, in certain cases, comprise 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.

[0007] In certain embodiments, exposure of the substrate to the reactive gas species may promote crosslinking in the photoresist layer. In these or other embodiments, exposure of the substrate to the reactive gas species may promote removal of low molecular weight species within the photoresist layer. For example, the low molecular weight species may contain zero, one, or two metal atoms per molecule. In some embodiments, exposure of the substrate to the reactive gas species may oxidize metal hydride species within the photoresist layer to metal hydroxide species.

[0008] In certain embodiments, the method may further comprise applying a vacuum to the processing chamber while baking the photoresist layer. In these or other embodiments, the method may further comprise controlling the moisture concentration within the processing chamber to remain within a target moisture concentration range while baking the photoresist layer. Similarly, the method may comprise controlling the oxygen concentration within the processing chamber to remain within a target oxygen concentration range while baking the photoresist layer. In some embodiments, the processing chamber may be maintained below atmospheric pressure while baking the photoresist layer. For example, in some cases, the processing chamber may be maintained below atmospheric pressure while baking the photoresist layer.

[0009] The support on which the substrate is placed may be temperature-controlled during baking of the photoresist layer. For example, in some embodiments, the method may further comprise raising the temperature of the substrate support on which the substrate is placed during baking of the photoresist layer. In these or other embodiments, the method may further comprise lowering the temperature of the substrate support on which the substrate is placed during baking of the photoresist layer. In some cases, the method comprises controlling the flow of reactive species into the processing chamber to achieve a target degree of crosslinking. Various different types of heat may be provided. In some embodiments, baking of the photoresist comprises heating the substrate on a hot plate. In some embodiments, baking of the photoresist layer comprises exposing the substrate to infrared and / or ultraviolet light. In some embodiments, baking of the photoresist layer may comprise heating the substrate from above. In these or other embodiments, baking of the photoresist layer may comprise heating the substrate from below.

[0010] The methods described herein may be used for different applications. In some cases, the photoresist layer is applied to the substrate but not yet patterned, and the baking is post-application bake (PAB). In other cases, the photoresist layer is applied to the substrate and patterned by partial exposure to EUV light, resulting in exposed and unexposed portions of the photoresist layer, and the baking is post-exposure bake (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.

[0011] In another aspect of embodiments of the present disclosure, an apparatus for baking a photoresist layer on a substrate is provided. The apparatus includes a processing chamber, an inlet for introducing a reactive gas species into the processing chamber, an outlet for removing materials from the processing chamber, a substrate support 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, the at least one processor being configured to control the apparatus to perform the method of the present application or the method described herein.

[0012] These and other aspects are further described below with reference to the drawings.

Brief Description of the Drawings

[0013]

Figure 1

[0014]

Figure 2

Modes for Carrying Out the Invention

[0015] In this specification, reference is made in detail to specific embodiments of the present disclosure. Examples of specific embodiments are shown in the accompanying drawings. While the present disclosure is described in conjunction with these specific embodiments, it will be understood that the intention is not to limit the present disclosure to such specific embodiments. On the contrary, the present disclosure is intended to cover alternatives, modifications, equivalents that may be included within its spirit and scope. In the following description, some specific details are set forth in order to provide a thorough understanding of the present disclosure. The present disclosure may be practiced without some or all of these specific details. In other instances, well-known process operations are not described in detail so as not to unnecessarily obscure the present disclosure.

[0016] Patterning of thin films in semiconductor processing is often an important step in semiconductor manufacturing. Patterning involves lithography. In conventional photolithography (such as 193nm photolithography), a chemical reaction occurs in the photoresist by exposing the photoresist to photons in a selected area defined by a photomask, a chemical contrast that can be used in the development process is formed, and a pattern is formed by removing specific portions of the photoresist, whereby a pattern is printed on the photosensitive photoresist film. The patterned and developed photoresist film can then be used as an etching mask for transferring the pattern to an underlying film composed of metal, oxide, etc.

[0017] Advanced technology nodes (as defined by the International Technology Roadmap for Semiconductors), including 22nm node, 16nm node, and subsequent nodes, require continuous improvement in lithography resolution. For example, at the 16nm node, the width of vias or lines in a damascene structure is typically about 30nm or less, which is impossible using simple 193nm photolithography or otherwise involves complex multipatterning methods.

[0018] Extreme ultraviolet (EUV) lithography can expand lithography technology by shifting to an image source wavelength shorter than that achievable with conventional photolithography methods. EUV light sources with wavelengths of about 10 - 20nm or 11 - 14nm (e.g., a wavelength of 13.5nm) can be used in state-of-the-art lithography tools (also called scanners). Since EUV light is strongly absorbed by a wide range of solid and liquid materials including quartz, water vapor, and atmospheric pressure gases, EUV scanners operate in a vacuum.

[0019] EUV lithography utilizes an EUV resist that can be patterned using EUV light to form a mask for use in etching an underlying layer. The EUV resist may be a polymer-based chemically amplified resist (CAR) formed by liquid spin-on technology. An alternative to the CAR is a metal oxide-based EUV photoresist (PR) film that can be directly photopatterned. Such a PR film may be formed by (wet) spin-on technology and is available from Inpria of Corvallis, Oregon, and is, for example, the film described in U.S. Patent Application Nos. US2017 / 0102612 and US2016 / 0116839, the disclosure of which is incorporated herein by reference for at least the disclosure of a photo-patternable metal oxide-containing film, or a dry deposition film described in PCT Application No. PCT / US19 / 31618, filed May 9, 2019, entitled METHODS FOR MAKING EUV PATTERNABLE HARD MASKS, the disclosure of which is incorporated herein by reference for at least the composition and patterning of a metal oxide film that can be directly photopatterned to form at least an EUV resist mask. These directly photo-patternable EUV resists may consist of, or include, metals with high EUV absorbance, their organometallic oxides / hydroxides, and other derivatives. Upon EUV exposure, EUV photons and the generated secondary electrons can induce chemical reactions such as the beta-H removal reaction in SnO x -based resists (and other metal oxide-based resists), and can provide a chemical function that promotes crosslinking and other changes in the resist film. These chemical changes can then be utilized in the subsequent development process to selectively remove the exposed or unexposed regions of the resist film and form an etching mask for pattern transfer.

[0020] This disclosure relates to lithographic patterning techniques and materials exemplified by EUV lithography, but it should be understood that it is also applicable to other next-generation lithography techniques. Currently, in addition to EUV with the standard 13.5 nm EUV wavelength in use and development, the radiation sources most relevant to such lithography are DUV (deep ultraviolet), generally referring to the use of excimer laser sources at 248 nm or 193 nm, X-rays (formally including EUV of X-rays in the low-energy range), and electron beams (which can include a wide range of energies). The specific method may depend on the specific materials and applications used in semiconductor substrates and final semiconductive devices. Thus, the methods described in this application are merely examples of methods and materials that can be used in this technology.

[0021] The photolithography process typically includes one or more baking steps to facilitate the chemical reactions necessary to create a chemical contrast between the exposed and unexposed regions of the photoresist. Such baking steps are typically carried out based on tracks for high-volume manufacturing (HVM), and the wafers are baked on a hot plate at a predetermined temperature under an atmosphere or, in some cases, under a N2 flow. During these baking steps, not only the baking atmosphere but also the introduction of additional reactive gas components into the atmosphere can be more thoroughly controlled to help further reduce the dose requirements and / or improve pattern fidelity.

[0022] This disclosure describes a new baking method that includes thorough control of the baking atmosphere and reactive gas introduction, and in some cases, thorough control of the heating rate of the baking temperature. Such a method may be particularly effective for metal oxide-based EUV photoresists (PR). Examples of effective reactive gases include water, hydrogen, oxygen, ozone, hydrogen peroxide, carbon monoxide, carbon dioxide, ammonia, nitrous oxide, nitric oxide, methylamine, dimethylamine, alcohol, acetylacetone, formic acid, oxalyl chloride, carboxylic acids, other amines, substituents of these materials, etc. The reactive gas is provided in the gas phase and may be vaporized before being supplied to the reaction chamber. Various exemplary gases are further described below.

[0023] Although the present disclosure is not limited to a specific logic or mechanism of operation, it is understood that these reactive gas molecules can accelerate the crosslinking reaction of the metal oxide-based EUV photoresist in the EUV exposure region (in this example, the region remaining for mask formation following development of the pattern film) by oxidation, coordination, or acid-base chemistry, while having a limited effect on crosslinking in the non-exposed regions. Alternatively, or in addition, in some cases the reactive gas molecules may further enhance the stability of the resist by promoting the removal of volatile species from the metal oxide-based EUV photoresist.

[0024] Figure 1 shows flowcharts according to various embodiments. In operation 101, a resist is deposited on a substrate. The substrate on which the resist is deposited typically includes an underlying material that will ultimately be etched after the resist is patterned / developed. In various embodiments, the substrate on which the resist is deposited may have an exposure layer such as amorphous carbon, spin-on carbon (SoC), spin-on glass (SoG), silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon oxycarbide. In many cases, the exposure layer is an ashing-capable hard mask (AHM). The resist deposited in operation 101 is a metal oxide-based EUV photoresist. This deposition may occur by wet spin-on techniques or dry vapor-based techniques such as chemical vapor deposition (CVD) and / or atomic layer deposition (ALD), which may be operated by thermal energy, plasma energy, or both. Next, in operation 103, the substrate is exposed to heat in a first baking process often referred to as a post-application bake (PAB). In operation 105, the substrate is exposed to EUV light to pattern the resist, thereby forming exposed and unexposed regions of the resist. Next, in operation 107, the substrate is exposed to heat in a second baking process often referred to as a post-exposure bake (PEB). Next, in operation 109, the resist is developed to selectively remove the unexposed regions. In various embodiments herein, the atmosphere to which the substrate is exposed may be controlled during the PAB of operation 103 and / or during the PEB of operation 107. For example, the substrate may be exposed to one or more reactive gases during these processes. Each baking process will be further described below. 1. Post-application bake (PAB)

[0025] Post-application bake is performed after the resist has been deposited on the substrate and before the resist is exposed to EUV light for patterning. Refer to operation 103 in FIG. 1. PAB may be performed to remove excess solvent (e.g., if the resist was deposited by spin-on method), to remove other low molecular weight species or volatile species, and to promote the desired degree of crosslinking in the resist. These features act to enhance the stability of the resist. For example, by removing non-bonded or loosely bonded low molecular weight or volatile species within the resist, the gas evolution of metal-containing molecules can be reduced to an acceptable amount (e.g., <1E10 molecules / (cm 2 ×month)). Since these materials can contaminate downstream processes, equipment, and substrates if not removed, removing them is an advantage. The crosslinking achieved during PAB also enhances the stability of the resist, but too much crosslinking can lead to an increase in line width roughness. Therefore, the crosslinking may be controlled to the desired degree during PAB.

[0026] In various embodiments of the present specification, the substrate may be exposed to a reactive gas during PAB. The reactive gas may facilitate the removal of low molecular weight species or volatile species. In various embodiments, the low molecular weight species removed during PAB may have zero metal atoms, one metal atom, or two metal atoms. In some cases, the low molecular weight species removed may include bimetallic species. Molecules having three or more metal atoms typically have a relatively heavy molecular weight, are relatively less volatile, and may substantially remain in the resist during PAB. In addition to promoting the removal of low molecular weight species, the reactive gas may promote the desired degree of crosslinking within the resist. As a result of these features, the use of a reactive gas during PAB may help to stabilize the resist.

[0027] The following provides exemplary processing apparatuses and reactive gases. In various embodiments, the substrate may be exposed to one or more of these reactive gases between PABs. In certain examples, the substrate may be exposed to a processing atmosphere having a controlled amount of oxygen and / or moisture (e.g., water vapor) along with an inert gas between PABs. In some embodiments, suitable gas sensors and feedback mechanisms may be used to ensure that the components of the processing atmosphere are controlled within a desired range.

[0028] In various embodiments, one or more processing conditions may be controlled as follows between PABs. The substrate may be heated to a high temperature of about 100 - 170 °C (e.g., in some cases about 100 - 130 °C). The pressure may be maintained at about 0.1 - 760 Torr (e.g., in some cases about 0.1 - 1 Torr). The substrate may be exposed to the high temperature for about 1 - 10 minutes (e.g., about 2 - 5 minutes). The inert gas may be flowed into the processing chamber at a rate of about 10 - 10,000 sccm. In a specific example, the oxygen (e.g., O2) concentration in the processing chamber may be controlled during PAB. In these or other embodiments, the moisture (e.g., H2O vapor) concentration may be controlled during PAB.

[0029] In some embodiments, PAB may be omitted. For example, when the resist is deposited using a dry vapor - based technique rather than a wet spin - on technique, PAB may not be necessary because there is no need to remove the excess solvent used to deposit the resist. However, even when the resist is deposited using a dry vapor - based technique, performing PAB may be advantageous to promote the desired degree of cross - linking and remove low - molecular - weight species or non - volatile species that may be a greater concern with dry vapor - based deposition techniques than with wet spin - on techniques. In some embodiments, PAB may be a conventional PAB. That is, PAB may occur 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 the post - exposure bake described further below. 2. Post-Exposure Bake (PEB)

[0030] Post-exposure bake is performed after the resist has been exposed to EUV light for patterning and before the resist is developed to remove its unexposed portions. Refer to operation 107 in FIG. 1. PEB may be performed, for example, for several purposes: 1) to facilitate the complete evaporation of organic fragments generated during EUV exposure, 2) to oxidize metal hydride species (other products from the beta-H removal reaction during EUV exposure) to metal hydroxides, and 3) to promote cross-linking between adjacent -OH groups to form a cross-linked metal oxide network.

[0031] The baking temperature is carefully selected to achieve optimal EUV lithography performance. If the PEB temperature is too low, not only will the removal of organic fragments be incomplete, but cross-linking will also be insufficient, resulting in insufficient chemical contrast for development at a given dose. If the PEB temperature is too high, it will cause adverse effects including severe oxidation and film shrinkage in the unexposed regions (in this example, the regions to be removed by development of the pattern film for mask formation), as well as undesirable interdiffusion at the interface between the PR and the underlayer (UL) (usually a spin-on carbon material), both of which will lead to a decrease in chemical contrast and an increase in the defect density due to insoluble residues. If the baking temperature and baking time are the only knobs, the adjustability and process window are often extremely limited.

[0032] As described herein, thoroughly controlling the introduction of the baking atmosphere and reactive gas species during the PEB process provides an additional chemical knob for fine-tuning the crosslinking process. For example, since the exposed area tends to be more polar than the unexposed area due to the loss of alkyl groups and the formation of hydride / hydroxide components, having polar and oxidizing molecules such as H2O2 present during the baking step can promote the oxidation of metal hydrides in the exposed area. Similarly, other gases as described in the following reactive gas column can vary the rate of hydride oxidation and hydroxide crosslinking reaction by oxidation, acid-base chemistry, coordination chemistry, and combinations thereof. The reactive gas may be provided in a controlled atmosphere using, for example, any of the apparatuses described in the following baking apparatus column. The reactive gas may be provided together with non-reactive gases such as N2, Ar, He, Ne, Kr, Xe. In some cases, air or clean dry air may be provided to the atmosphere during PEB.

[0033] The ability to adjust the rate of the crosslinking reaction in metal oxide-based EUV photoresist materials provides a wider process window that enables further optimization of lithography performance by minimizing interdiffusion and other related defect formation mechanisms. For example, if the reactive gas can efficiently lower the baking temperature requirements, concerns about interdiffusion at the PR / UL interface can be alleviated, which would be beneficial for defect reduction.

[0034] In certain embodiments, one or more processing conditions between PEBs may be controlled as follows. The substrate may be heated to a high temperature of about 100 - 250 °C (for example, in some cases about 120 - 200 °C). The pressure may be maintained at about 0.1 - 760 Torr (for example, in some cases about 0.1 - 1 Torr). The substrate may be exposed to the high temperature for about 1 - 10 minutes (for example, about 2 - 5 minutes). An inert gas may be flowed into the processing chamber at a rate of about 10 - 10,000 sccm. In certain examples, the oxygen (e.g., O2) concentration in the processing chamber may be controlled during PEB. In these or other embodiments, the moisture (e.g., H2O vapor) concentration may be controlled during PEB.

[0035] 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, and in other cases, one or more additional reactive gases may be provided along with ammonia. In some embodiments, ammonia may be provided at a concentration of about 0.001 to 5.0 (vol)%, and in some cases, at atmospheric pressure, or at a partial pressure of about 1 to 100 mTorr, or about 1 to 10 mTorr if the processing chamber is under vacuum, at a concentration of about 0.001 to 0.5 (vol)%. The duration of PEB (and / or the duration of substrate exposure to ammonia during PEB) may be from about 5 seconds to about 10 minutes, and in some cases, from about 5 seconds to 1 minute. After the substrate has been exposed to ammonia, the processing chamber may be purged with an inert gas. In various embodiments, the purge period of the inert gas may be the same length as, or longer than, the period during which the substrate is exposed to ammonia. These steps may promote the alkali-catalyzed reaction of M-OH condensation / crosslinking to form relatively high molecular weight low-volatile species, resulting in a more stable photoresist film as described above. These steps may cure and densify the film region exposed to EUV light (or other types of lithographic patterning radiation), and may enable these effects at a baking temperature lower than the baking temperature 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 using alternative or additional reactive gases described herein, including but not limited to other volatile amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, pyridine, etc.

[0036] In some embodiments, PEB may be a conventional PEB. That is, PEB may be performed without providing a reactive gas to the substrate and / or in an uncontrolled atmosphere. In such cases, one or more reactive gases may be provided to the substrate during PAB. 3. Reactive Gas

[0037] In various embodiments of the present specification, the substrate may be exposed to one or more reaction gases during the photoresist baking operation. As described above, the reaction gas may promote the desired degree of crosslinking, promote the removal of low molecular weight species or volatile species, and / or stabilize the photoresist.

[0038] Several different reaction gases may be used. Examples of effective reaction 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), alcohol (C n H 2n+1 OH (including but not limited to methanol, ethanol, propanol, and butanol)), acetylacetone (CH3COCH2COCH3), formic acid (HCOOH), oxalyl chloride ((COCl)2), carboxylic acid (C n H 2n+1 COOH), and other small molecule amines (NR 1 R 2 R 3 (R 1 、R 2 、R 3 are each independently selected from hydrogen, hydroxyl, aliphatic, haloaliphatic, haloheteroaliphatic, heteroaliphatic, aromatic, aliphatic aromatic, heteroaliphatic aromatic, or combinations thereof)), etc. Substituted forms of these reaction gases may be used. In some cases, the substrate may be exposed to two or more reaction gases during the photoresist baking operation.

[0039] The reactive gas may interact with the photoresist by oxidation, coordination, or acid-base chemistry. When the reactive gas is supplied during the PEB operation, the reactive gas may preferentially interact with the photoresist in the region exposed to EUV light. This preferential interaction may result from chemical changes that occur during EUV exposure (e.g., loss of alkyl groups in the photoresist).

[0040] Following exposure of the substrate 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 purge period of the inert gas may be at least as long as the period during which the substrate is exposed to the reactive gas. 4. Temperature Gradient

[0041] In some embodiments, the rate at which the substrate temperature changes may be controlled during the baking process. In some cases, rapid heating and rapid cooling can be problematic. By controlling the rate at which the substrate temperature rises and falls, problems associated with rapid heating and rapid cooling are avoided. Additionally, the rate at which the baking temperature rises and / or falls may be controlled to finely tune the crosslinking reaction in the resist. 5. Baking Apparatus

[0042] The baking operations described herein may occur in a variety of different types of processing apparatuses. In some cases, the processing apparatus may have a sealed chamber that is sealed from the ambient environment. In other cases, the processing apparatus may have an open chamber that is not sealed from the surroundings. In certain cases where an open chamber is used, the substrate may be processed based on tracks that can operate continuously or discontinuously. Generally, a sealed chamber provides better control over the processing atmosphere and additional safety against potentially harmful reactive chemicals. However, for example, in high-volume production where non-hazardous chemicals are used, an open chamber may be preferred.

[0043] This chamber may comprise one or more inlets for providing a desired processing atmosphere. The desired processing atmosphere may include one or more reaction gases as described above. Therefore, the inlets may be in fluid connection with a reaction gas source. The reaction gas may flow from the reaction gas source through a gas supply line and into the chamber through the inlets. If the reaction gas is a liquid at an appropriate temperature, it may be stored as a liquid and vaporized prior to supply to the gas supply line / inlet / chamber. Also, in certain embodiments, air and / or an inert gas (e.g., N2, Ar, He, Ne, Kr, Xe, etc.) may be provided to the processing atmosphere. These may likewise flow from a gas source through a gas supply line and into the chamber through the inlets. In some cases, the processing atmosphere may not include air.

[0044] The chamber may also comprise one or more outlets for removing material from the chamber. The outlets may be in fluid connection with a vacuum source to enable active removal of gas species from the chamber. The vacuum connection outlets may be used in both sealed and open chambers. When used in a sealed chamber, the vacuum connection outlets may be capable of processing at near atmospheric pressure. In the case of an open chamber where the processing chamber is not sealed from the surroundings, the outlet may be a path through which gas can passively escape from the chamber.

[0045] As described above, in certain embodiments, the atmosphere within the chamber may be controlled during a baking process. In some cases, the concentration of a reaction gas (e.g., oxygen and / or water and / or other reaction gases described herein) may be actively controlled during the baking process. In addition to the inlets and outlets described above, the chamber may further comprise sensors (e.g., residual gas analyzers, Fourier transform infrared spectroscopy sensors, etc.) for monitoring the components of its atmosphere. These sensors may be used to provide feedback for actively controlling the components of the baking atmosphere.

[0046] To bake the photoresist, the chamber comprises one or more heating elements configured to heat the substrate. The heating elements may heat the substrate from above and / or below. The heating elements may heat the front side of the substrate (e.g., where the semiconductor device / structure is formed) and / or the back side of the substrate. Various different types of heating elements may be used singly or in combination with each other. Examples of heating elements may include a heated substrate support (e.g., pedestal, chuck, etc.), as well as radiation sources such as infrared lamps and / or ultraviolet lamps.

[0047] In some embodiments, the chamber may comprise one or more cooling elements configured to cool the substrate. For example, the substrate support may be configured to cool the substrate. In one embodiment, the substrate support may comprise a cooling channel through which a heat exchange fluid flows to cool the substrate. For specific applications, other heat exchange devices may be used as needed. The cooling elements may be particularly effective in controlling the rate at which the substrate cools after the baking operation.

[0048] The chamber may also comprise a temperature sensor for monitoring the temperature of the substrate and / or the substrate support during the baking operation. In one example, the chamber comprises a pyrometer for measuring the temperature of the substrate surface during baking. The temperature measurements from the pyrometer or other temperature sensors may be used as feedback to actively control the substrate temperature during baking.

[0049] Figure 2 shows a schematic diagram of a processing chamber 200 according to an embodiment. In this example, the processing chamber 200 is a sealed chamber having a controllable atmosphere. The substrate 201 may be placed on a substrate support 202 that can also heat and / or cool the substrate. In some cases, alternative or additional heating and cooling elements may be provided. The processing gas enters the processing chamber 200 through the inlet 203. Materials are removed from the processing chamber 200 through an outlet 204 that 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 further described below. Additionally, a sensor 205 may be provided, for example, to monitor the temperature and / or composition of the atmosphere in the processing chamber 200. The values from the sensor 205 may be used by the controller 206 in an active feedback loop.

[0050] The chamber in which baking is performed may be configured in several forms. In some embodiments, this chamber is the same as the chamber used to deposit photoresist and / or the same as the chamber used to expose photoresist to EUV light and / or the same as the chamber used to develop photoresist. In some embodiments, this chamber is a dedicated baking chamber not used for other processes such as deposition, etching, EUV exposure, or photoresist development. This chamber may be a stand-alone chamber or may be integrated with a larger processing tool such as a deposition tool used to deposit photoresist, an EUV exposure tool used to expose photoresist to EUV light, and / or a development tool used to develop photoresist. The chamber used for baking may be combined with one or more of these tools as needed for a particular application.

[0051] This chamber may include a controller. In some embodiments, the controller may be part of a system that may be part of the above example. Such a system may include a semiconductor processing apparatus including a processing tool, a chamber, a processing platform, and / or certain processing components (such as a wafer pedestal, a gas flow system, etc.). These systems may be integrated with electronics for controlling the operation of the semiconductor wafer or substrate before, during, and after processing. These electronics may be referred to as a “controller” and may control various components or sub-components of the system. The controller may be programmed to control any process disclosed herein, including the supply of process gases, temperature setting (e.g., heating and / or cooling), pressure setting, vacuum setting, power setting, radio frequency (RF) generator setting, RF matching circuit setting, frequency setting, flow rate setting, fluid supply setting, position movement setting, tools connected or coupled to a particular system and other transfer tools, and / or wafer loading and unloading to / from a load lock, depending on the processing requirements and / or the type of system.

[0052] Generally, a controller may be defined as an electronic device having various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. The integrated circuit may include a chip in the form of firmware that stores program instructions, a digital signal processor (DSP), a chip defined as an application specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). The program instructions are instructions transmitted to the controller in the form of various individual settings (or program files) that may define operating parameters for performing a particular process on or for a semiconductor wafer or for a system. In some embodiments, the operating parameters may be part of a recipe defined by a process engineer to implement one or more processing steps during the manufacture of one or more layers, materials, metals, oxides, silicon, silicon dioxide, surfaces, circuits, and / or wafer dies.

[0053] In some embodiments, the controller may be part of a computer that is integrated or coupled with the system, or otherwise network-connected to the system, or a combination thereof, or may be coupled to such computer. For example, the controller may be within a "cloud" that enables remote access to wafer processing, or may be all or part of a fab host computer system. The computer enables remote access to the system, monitors the progress of manufacturing operations, examines the history of past manufacturing operations, examines trends or implementation criteria from multiple manufacturing operations to change the parameters of the current process, set the processing steps following the current process, or initiate a new process. In some examples, a remote computer (e.g., a server) can provide a process recipe to the system through a network that can 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 transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data that specify the parameters of each processing step performed during one or more operations. It should be understood that the parameters may be specific to the type of process being performed and the type of tool configured to be coupled to or controlled by the controller. Thus, as described above, the controller may be distributed, for example, by including one or more separate controllers network-connected to each other and cooperating towards a common purpose such as the processes and controls described herein. An example of a controller distributed for such a purpose would be one or more integrated circuits on a chamber that are located remotely (e.g., at the platform level or as part of a remote computer) and communicate with one or more integrated circuits to cooperate in controlling the process of the chamber.

[0054] Rather than being limiting, the exemplary systems may include a plasma etching chamber or module, a deposition chamber or module, a spin rinse chamber or module, a metal plating chamber or module, a cleaning chamber or module, a bevel edge etching 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 etching (ALE) chamber or module, an ion implantation chamber or module, a track chamber or module, and other semiconductor processing systems that may be relevant or used in the fabrication and / or manufacture of semiconductor wafers.

[0055] As described above, the controller may communicate with one or more of other tool circuits or modules, other tool components, cluster tools, other tool interfaces, adjacent tools, proximate tools, tools installed throughout the factory, a main computer, another controller, or a tool used for material transport to and from a wafer container with respect to a tool location and / or load port in a semiconductor manufacturing facility, depending on the processing steps performed by the tool. Conclusion

[0056] A baking method for improving EUV lithography performance of a metal-containing EUV resist is disclosed.

[0057] The examples and embodiments described herein are for illustrative purposes, and it is understood that various modifications or changes from that perspective will be suggested to those skilled in the art. Various details have been omitted for clarity, but various conceptual changes may be made. Thus, this example should be considered illustrative rather than limiting, and the present disclosure should not be limited to the details described herein, but may be modified within the scope of the present disclosure.

Claims

1. A method of baking a photoresist layer on a substrate, comprising: receiving the substrate in a processing chamber, the substrate having thereon the photoresist layer, the photoresist layer including a metal-containing photoresist material; flowing a reactive gas species from a gas source through a gas supply line into the processing chamber and exposing the substrate in the processing chamber to the reactive gas species; baking the photoresist layer while the substrate is being exposed to the reactive gas species. A method as described above.

2. The method according to claim 1, wherein the photoresist layer includes an extreme ultraviolet (EUV) photoresist material.

3. The method according to claim 2, wherein the reactive gas species includes a gas selected from the group consisting of water, hydrogen, oxygen, ozone, hydrogen peroxide, carbon monoxide, carbon dioxide, ammonia, nitrous oxide, nitric oxide, alcohol, acetylacetone, formic acid, oxalyl chloride, pyridine, carboxylic acid, amine, and combinations thereof.

4. The method according to claim 3, wherein the reactive gas species includes the water.

5. The method according to claim 3, wherein the reactive gas species includes the hydrogen.

6. The method according to claim 3, wherein the reactive gas species includes the oxygen.

7. The method according to claim 3, wherein the reactive gas species includes the ozone.

8. The method according to claim 3, wherein the reactive gas species includes the hydrogen peroxide.

9. The method according to claim 3, wherein the reactive gas species includes the carbon monoxide.

10. The method according to claim 3, wherein the reactive gas species includes the carbon dioxide.

11. The method according to claim 3, wherein the reactive gas species includes the ammonia.

12. The method according to claim 11, wherein the baking of the photoresist occurs after the photoresist has been exposed to EUV light for patterning of the photoresist, and any of the following conditions is satisfied: (i) the processing chamber is maintained at atmospheric pressure while baking the photoresist, and the ammonia is provided at a concentration of about 0.001 to 5 (vol) %. (ii) The method wherein the processing chamber is maintained at a near-atmospheric pressure while baking the photoresist, and the ammonia is provided at a partial pressure of about 1 to 100 mTorr.

13. The method according to claim 3, wherein the reaction gas species includes the nitrous oxide and / or the nitric oxide.

14. The method according to claim 3, wherein the reaction gas species includes the alcohol.

15. The method according to claim 3, wherein the reaction gas species includes the acetylacetone.

16. The method according to claim 3, wherein the reaction gas species includes the formic acid.

17. The method according to claim 3, wherein the reaction gas species includes the oxalyl chloride.

18. The method according to claim 3, wherein the reaction gas species includes the carboxylic acid.

19. The method according to claim 3, wherein the reaction gas species includes the amine.

20. The method according to claim 19, wherein the amine includes methylamine, dimethylamine, and / or trimethylamine.

21. The method according to claim 19, wherein the amine includes ethylamine, diethylamine, and / or triethylamine.

22. The method according to any one of claims 2 to 21, wherein the reaction gas species has oxidizing properties.

23. The method according to any one of claims 2 to 22, wherein the reaction gas species has polarity.

24. The method according to any one of claims 2 to 23, wherein exposing the substrate to the reaction gas species promotes crosslinking in the photoresist layer.

25. The method according to any one of claims 2 to 24, wherein exposing the substrate to the reaction gas species enhances the stability of the photoresist layer.

26. The method according to any one of claims 2 to 25, wherein exposing the substrate to the reaction gas species promotes the removal of low molecular weight species within the photoresist layer.

27. The method according to claim 26, wherein the low molecular weight species comprises zero, one, or two metal atoms per molecule.

28. The method according to any one of claims 2 to 27, Exposing the substrate to the reaction gas species is a method of oxidizing the metal hydride species of the photoresist layer to metal hydroxide species.

29. The method according to any one of claims 2 to 28, further comprising: applying a vacuum to the processing chamber while baking the photoresist layer.

30. The method according to any one of claims 2 to 29, further comprising: controlling the moisture concentration in the processing chamber to remain within a target moisture concentration range while baking the photoresist layer.

31. The method according to any one of claims 2 to 30, further comprising: controlling the oxygen concentration in the processing chamber to remain within a target oxygen concentration range while baking the photoresist layer.

32. The method according to any one of claims 2 to 31, wherein the processing chamber is maintained at a pressure below atmospheric pressure while baking the photoresist layer.

33. The method according to claim 32, wherein the processing chamber is maintained at a pressure below atmospheric pressure while baking the photoresist layer.

34. The method according to any one of claims 2 to 33, further comprising: raising the temperature of the substrate support on which the substrate is placed while baking the photoresist layer.

35. The method according to any one of claims 2 to 34, further comprising: lowering the temperature of the substrate support on which the substrate is placed while baking the photoresist layer.

36. The method according to any one of claims 2 to 35, further comprising: controlling the flow of the reaction species into the processing chamber to achieve a target degree of crosslinking.

37. The method according to any one of claims 2 to 36, wherein baking the photoresist layer comprises heating the substrate on a hot plate.

38. The method according to any one of claims 2 to 37, wherein baking the photoresist layer comprises exposing the substrate to infrared and / or ultraviolet light.

39. The method according to any one of claims 2 to 38, wherein baking the photoresist layer comprises heating the substrate from above.

40. The method according to any one of claims 2 to 39, wherein baking the photoresist layer comprises heating the substrate from below.

41. The method according to any one of claims 2 to 40, wherein the photoresist layer is applied to the substrate but not yet patterned, and the baking is post-application bake (PAB).

42. The method according to any one of claims 2 to 41, wherein the photoresist layer is applied to the substrate and patterned by partial exposure to EUV light, resulting in exposed and unexposed portions of the photoresist layer, and the baking is post-exposure bake (PEB).

43. The method according to claim 42, wherein the reaction gas species comprises polar and oxidizing molecules.

44. The method according to claim 43, wherein the reaction gas species comprises hydrogen peroxide.

45. An apparatus for baking a photoresist layer on a substrate, comprising: a processing chamber; an inlet for introducing a reaction gas species into the processing chamber; an outlet for removing materials from the processing chamber; a substrate support 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, the at least one processor being configured to control the apparatus to perform any of the methods of claims 1 to 44. An apparatus.

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