Process environment for inorganic resist patterning

Abstract

It has been shown that the processing of radiation-patternable organometallic coatings can be improved by appropriate selection of post-processing conditions between the deposition and development of the pattern. In particular, the coated wafer can be subjected to process delays to allow for aging of the coating at various process points, especially after irradiation. The process delays can be interspersed with heating steps. The atmosphere above the coated wafer during various process steps can be adjusted to obtain desired improvements in pattern development. Reactive gases can be beneficial in connection with improved coating properties.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to co-pending U.S. Provisional Patent Application No. 62 / 984,023, filed March 2, 2020, to Telecky et al., entitled "Process Environment for Inorganic Resist Patterning," which is incorporated herein by reference.

[0002] The present invention relates to the processing of radiation-sensitive organometallic patterning compositions, particularly organotin oxide hydroxide-based compositions, in the context of deposition via pattern development. [Background technology]

[0003] Semiconductor manufacturing requires both high performance and high reproducibility of the materials and processes that comprise the fabrication of semiconductor devices. For example, during high volume manufacturing, it is desirable for lithographic processes to repeatably produce features of the same size and shape across many wafers and over many days; therefore, high patterning stability of lithographic materials is desirable. Summary of the Invention [Problem to be solved by the invention]

[0004] Metal oxide hydroxide photoresists, particularly organo-tin oxide materials, are promising materials for semiconductor patterning and manufacturing due to their high absorbance, high pattern fidelity, and high etch contrast. Despite these advantages, many of these materials are known to be sensitive to environmental factors, such as humidity and composition of the atmosphere to which the wafer is exposed throughout the multi-step manufacturing process. The present invention allows for reduced processing variability and / or improved sensitivity of metal oxide hydroxide photoresists. [Means for solving the problem]

[0005] The methods described herein improve process variability of metal oxide hydroxide photoresists by treating the photoresist in the presence of controlled concentrations of reactive gases throughout wafer processing. The invention further relates to exposing radiation-patterned metal oxide hydroxide photoresist coatings to atmospheres containing controlled and / or targeted concentrations of reactive gases, such as carbon dioxide, carbon monoxide, and water. The reactive gases can be introduced during typical processing or at selected temperatures.

[0006] The present invention further relates to exposing the radiation-patterned metal oxide hydroxide coating to a chemical capable of reacting with the exposed material to convert at least a portion of either the irradiated or unirradiated material to a new composition.

[0007] Specifically, the present invention relates to a method for improving the processing of a radiation-patternable organotin-based coating having a thickness of about 1 nm to about 500 nm on a wafer, the method comprising storing the wafer having the coating for aging in an atmosphere at a pressure of at least about 200 Torr after irradiation and prior to pattern development, the aging being for at least about 20 minutes.

[0008] In a further embodiment, the present invention provides a method for forming a radiation-patternable organotin-based coating on a wafer having an average thickness of from about 1 nm to about 500 nm, the method comprising contacting the wafer having the coating with an atmosphere containing a CO concentration of from about 500 ppm to about 10 mole percent prior to development to form a physical pattern, wherein the coating is formed of an organotin-based compound having the formula RSnO x OH 3-x wherein R is an organic ligand having 1 to 31 carbon atoms, the carbon atoms being bonded to Sn, and one or more carbon atoms optionally being substituted with one or more heteroatom functional groups.

[0009] In another embodiment, the invention relates to a method for improving the processing of a radiation-patternable organotin-based coating comprising an organotin oxide hydroxide having Sn—C bonds, the coating having a thickness of about 1 nm to about 500 nm, the method comprising, after irradiation, contacting a wafer having the organotin oxide hydroxide coating with an atmosphere comprising a reactive gas to alter the tin-bonding ligands in the irradiated areas, the reactive gas comprising SO, H, S, CH, SH, CO, COS, HOOH, NH, H, O, nitric oxide, PH, SiH, CH, ethylene oxide, or a combination thereof.

[0010] In another embodiment, the present invention relates to a method for improving the processing of a radiation-patternable organotin-based coating comprising an organotin oxide hydroxide having Sn—C bonds, the coating having a thickness of from about 1 nm to about 500 nm on a wafer, the method comprising contacting the organotin oxide hydroxide coating with an atmosphere comprising a reactive gas, the reactive gas comprising SO, HS, CH, SH, CO, COS, H, O, nitric oxide, PH, SiH, HOOH, NH, CH, or ethylene oxide, and the reactive gas differentially alters tin-bonding ligands in irradiated and non-irradiated portions of the coating such that a latent image formed by radiation exposure results in greater contrast in development rates between irradiated and non-irradiated portions of the coating. In some embodiments, the increased contrast can result in an increase in the critical dimension of the developed structures of at least about 0.25 nm. [Brief explanation of the drawings]

[0011]

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[0012] The patterning of organotin-based resists can be improved through post-coating treatment of the as-deposited coating, leading to development of the radiation-formed image. Controlling the partial pressure of reactive gases to which metal oxide hydroxide-coated wafers are exposed during processing can reduce material variability and subsequent patterning variability. Additionally or alternatively, aging the wafer after irradiation can enhance the condensation or network formation process of the irradiated material to improve patterning contrast, and the aging atmosphere can also be tailored to improve processing. Part of the improved processing can include aging the wafer after irradiation before development, and some desirable aging can be performed in an inert atmosphere. Specifically, in some embodiments, the present disclosure is directed to methods of exposing metal oxide hydroxide photoresists to specific concentrations of reactive gases. Furthermore, by exposing radiation-patterned metal oxide hydroxide materials to specific reactive gases, the patterned material can react and be converted, at least in part, to a new composition. Alternatively or additionally, unirradiated portions of the metal oxide hydroxide coating can react with the reactive gas and be converted, at least in part, to a new composition. In some embodiments, the resulting new compositions comprised of this modified material may exhibit improved etch selectivity, hardness, stress, and stability, among other properties, compared to unmodified compositions. Additionally or alternatively, exposing the radiation-patterned metal oxide hydroxide photoresist material to a reactive gas may alter the surface of the material, resulting in significantly altered polarity or surface energy differences compared to the initial material surface, and thus significantly different etch selectivity or adhesion.

[0013] Wafer processing generally includes all of the individual processes that a substrate or wafer undergoes, from coating / deposition to removal from the substrate. Additionally, a tone reversal process may be implemented to reverse the tone photoresist pattern. Generally, wafer processing may include coating, baking, a transfer step, backside and edge bead rinsing, radiation exposure, development, annealing, and etching. It has been discovered that it is desirable to control the presence and concentration of reactive gases during wafer processing, as well as the timing of the processes.

[0014] When exposed to appropriate gases or other reactive species, inorganic materials, metal oxides, and metal hydroxides can react to form new compounds that exhibit different properties and / or composition than the starting materials. This is depicted schematically in FIG. 1. Irradiated structure 100 includes irradiated coating material 102 and unirradiated coating material 104 on substrate 106. After post-irradiation treatment 108, treated structure 110 includes converted material 112 adjacent to unirradiated coating material 104 on substrate 106. After etching 118, etched structure 120 has the treated coating material removed.

[0015] For example, many metal oxides can be converted to a lower oxidation state or its elemental form by exposure to hydrogen gas to drive a reduction reaction. In addition, many metals have multiple stable oxidation states, e.g., Fe 2+ / Fe 3+ , Sn 2+ / Sn 4+ , Sb 3+ / Sb 5+ , and their corresponding oxides can exhibit different physical and chemical properties, such as conductivity, solubility, hardness, and density. In some cases, only a portion of the patterned metal oxide material is transformed into a new composition. Ultimately, these different properties may then enable subsequent etching processes, including development processes, that may not otherwise be achievable.

[0016] The present process may be based on the presence of nonvolatile metal ions within metal oxide hydroxide coating materials. In contrast to conventional polymer patterning materials, materials containing metal ions, such as metal oxide hydroxide materials, can undergo chemical changes related to their oxidation state and / or ligand structure when exposed to and reacted with specific reactive compositions, such as gases, liquids, or plasmas. Many metals have multiple stable oxidation states that can be selectively formed by controlling appropriate reaction conditions. Furthermore, metal oxides and hydroxides are also known to incorporate various anions and counterions into their structures, resulting in the formation of new compositions with properties different from those of the starting materials. Organometallic compositions, such as organotin oxide hydroxides and antimony oxide hydroxides, also have the ability to incorporate such counterions due to their metal oxide hydroxide properties, such as the presence of metal-oxygen and metal-hydroxide bonds.

[0017] To select effective processing conditions for a patterning process, empirical evaluation of the properties of the resulting coating material can generally be performed. While heating may not be required for successful application of the process, it may be desirable to heat the coated substrate to accelerate processing and / or improve reproducibility of the process and / or to promote evaporation of volatile by-products. In embodiments where heat is applied to remove solvent in a pre-exposure bake, the coating material can be heated to a temperature of from about 100°C to about 600°C, and in further embodiments, from about 55°C to about 225°C. Heating to remove solvent typically can be carried out for at least about 0.1 minutes, from about 0.5 minutes to about 30 minutes in further embodiments, and from about 0.75 minutes to about 10 minutes in other embodiments. The final film thickness is determined by the bake temperature and time as well as the initial concentration of the precursor. A person of ordinary skill in the art will recognize that additional ranges of heating temperatures and times within the explicit ranges above are contemplated and are within the scope of the present disclosure. As a result of heat treatment, possible hydrolysis, and densification of the coating material, the coating material may exhibit an increase in refractive index and radiation absorption without a significant loss of dissolution rate contrast.

[0018] The deposition process determines the wet coating thickness. Typically, the solvent is removed to leave a solid layer as a coating on the substrate for further processing. In suitable embodiments, solution concentration and process conditions influence the dry coating thickness, which can be selected to achieve the desired patternability. Similarly, in vapor-phase coating processes, vapor deposition parameters, such as deposition rate and time, can influence the coating thickness. The average dry coating thickness can be from about 1 nm to about 1000 nm, in some embodiments from about 2 nm to about 300 nm, in further embodiments from about 3 nm to about 200 nm, and in other embodiments from about 3 nm to about 80 nm. Correspondingly, in the vapor deposition described below, the coating thickness can be adjusted via process conditions to achieve the desired layer thickness of the coating. A person of ordinary skill in the art will recognize that additional average thickness ranges within the ranges explicitly stated above are contemplated and are within the scope of the present disclosure.

[0019] For example, water vapor can react with metal oxides and hydroxides to form metal hydroxides, which can then undergo further condensation polymerization reactions depending on the reaction. As the reaction progresses, the resulting metal oxide hydroxide material can form a network through hydrogen bonding or condense with the elimination of water to form a material with a reduced development rate. Therefore, by exposing the photoresist to water vapor, the dose required to pattern the metal oxide hydroxide photoresist can be reduced to produce a desired feature size. Specifically, exposing radiation-patterned materials to water vapor can improve the sensitivity of the photoresist.

[0020] Because the equilibrium vapor pressure of water varies proportionally with temperature, the moisture content of air is typically expressed as a percent relative humidity (RH%). At a given temperature, a higher RH% suggests that more water vapor is present in the air than a lower RH% value. To reduce process variability, each step in the processing of a substrate, from coating to post-development annealing, can be performed in an environment with a constant relative humidity, typically 40%-60%. In other embodiments, the selected RH% can vary for different steps throughout the lithographic process, but within each step, it will generally be desirable to maintain a nearly constant RH%. Typically, the relative humidity (RH) is set to 40%-60% for wafer patterning equipment and maintained near this value. The RH of the atmosphere surrounding the wafer during processing, such as in the coating or bake module within the wafer track, can be set to a different value than in larger equipment. In some embodiments, the RH of the processing atmosphere can be higher than in larger equipment, for example, 60%-80%, in other embodiments 80%-90%, and in further embodiments, greater than 90%. In other embodiments, the RH of the processing atmosphere can be lower than in larger facilities, e.g., 20%-40%, in other embodiments, 10%-20%, and in further embodiments, less than 10%. In some embodiments, the RH of the processing atmosphere can vary to about 10% or less, in other embodiments, about 5% or less, and in further embodiments, about 2% or less. Relative humidity and temperature are related to the partial pressure of water vapor, and one of ordinary skill in the art can interconvert these values. When an inert atmosphere, such as nitrogen or argon, is used for processing, the moisture concentration can be very low, such as 10 ppm or less on a molar basis, and the corresponding RH value is temperature dependent. One of ordinary skill in the art will recognize that additional ranges of relative humidity and variations of relative humidity within the ranges explicitly stated above are contemplated and within the scope of the present disclosure.

[0021] Additionally, in some embodiments, it may be desirable to blanket the coated wafer with an inert atmosphere during at least part of the process. For example, nitrogen (N), Ar, other inert gases, or combinations thereof, can be used. While pressure can be individually adjusted, the use of near-atmospheric pressures allows for simpler equipment with vented flows to the atmosphere. Alternatively, pressure-regulated chambers are readily available for wafer processing using commercially available equipment. Suitable pressure ranges are further described below. An example is presented below in which improved processing results were obtained using N during 254 nm UV irradiation or during a delay after irradiation. The inert gas need not be completely pure to be effective; generally, it is desirable for the inert gas to be at least 95 mol% pure, at least about 98 mol% in further embodiments, at least about 99% pure in other embodiments, and at least about 99.9 mol% pure in other embodiments. A person of ordinary skill in the art will recognize that additional ranges within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0022] The general process flow is shown schematically in FIG. 1. First, a wafer is coated with a radiation-patternable organometallic oxide hydroxide resist. The coated wafer is then dried, which may include a post-apply bake (PAB). While heating may not be required for successful application of the process, it may be desirable to heat the coated substrate to accelerate processing and / or improve reproducibility of the process and / or to promote evaporation of hydrolysis by-products, such as amines and / or alcohols. In embodiments where heat is applied to remove solvent, the coating material can be heated to a temperature of from about 45° C. to about 250° C., and in further embodiments, from about 55° C. to about 225° C. Heating to remove solvent typically can be carried out for at least about 0.1 minute, from about 0.5 minutes to about 30 minutes in further embodiments, and from about 0.75 minutes to about 10 minutes in other embodiments. A person of ordinary skill in the art will recognize that additional ranges of heating temperatures and times within the explicit ranges above are contemplated and are within the present disclosure. As a result of heat treatment, hydrolysis, and densification of the coating material, the coating material may exhibit an increase in refractive index and radiation absorption without a significant loss of contrast.

[0023] After drying and application of any PAB, the coated wafer can be stored for a period of time before irradiation. A particular process track can have a standard amount of time to transfer the coated wafer to the radiation exposure position. A post-coating delay can be introduced to further age the dried coated wafer before radiation exposure for a period of time longer than the normal process time for transferring the wafer to the exposure station of the process track. The post-coating delay can be at least 20 minutes, in further embodiments at least about 1 hour, in further embodiments at least about 13 hours, and in some embodiments from about 2 hours to about 7 days. A person of ordinary skill in the art will recognize that additional ranges within the explicit ranges above are contemplated and are within the scope of the present disclosure. The post-coating delay (PCD) can be performed by blanketing the wafer with a particular atmosphere, such as air, air containing a modifying gas, N, argon, or other inert gas, or vacuum.

[0024] Referring to FIG. 2, after any post-coating delay, the structure is subjected to radiation exposure. Patterned radiation is directed at the radiation-sensitive coating to form a latent image in the organometallic resist. The radiation can generally be directed at the coated substrate through a mask, or the radiation beam can be controllably scanned across the substrate. Generally, the radiation can include electromagnetic radiation, electron beam (beta radiation), or other suitable radiation. Generally, the electromagnetic radiation can have a desired wavelength or range of wavelengths, such as visible radiation, ultraviolet radiation, extreme ultraviolet radiation, or X-ray radiation. The achievable resolution of the radiation pattern generally depends on the radiation wavelength, with higher resolution patterns generally being achievable with shorter wavelength radiation. Therefore, it may be desirable to use ultraviolet radiation, extreme ultraviolet radiation, or X-ray radiation, or electron beam irradiation, to achieve particularly high resolution patterns.

[0025] According to the international standard ISO 21348 (2007) (incorporated herein by reference), ultraviolet light spans wavelengths from 100 nm to less than 400 nm. Krypton fluoride lasers can be used as 248 nm ultraviolet light sources. The ultraviolet range can be subdivided in several ways under accepted standards, such as extreme ultraviolet (EUV) from 10 nm to less than 121 nm and far ultraviolet (FUV) from 122 nm to less than 200 nm. The 193 nm line from an argon fluoride laser can be used as a radiation source for FUV. EUV light at 13.5 nm has been used in lithography, and this light is generated from Xe or Sn plasma sources excited using high-energy lasers or discharge pulses. Soft x-rays can be defined as 0.1 nm to less than 10 nm.

[0026] Electromagnetic dosage can be characterized by fluence or dose, which is defined by the integrated radiant flux over the exposure time. Generally, a suitable EUV radiation fluence is about 1 mJ / cm. 2 ~Approx. 175mJ / cm 2 and in a further embodiment about 2 mJ / cm 2 ~Approx. 150mJ / cm 2 and in a further embodiment about 3 mJ / cm2 ~Approx. 125mJ / cm 2 A person of ordinary skill in the art will recognize that additional ranges of radiation fluence within the explicit ranges above are contemplated and are within the present disclosure.

[0027] Depending on the design of the coating material, it is possible to induce a large contrast in material properties between irradiated and unirradiated regions of the coating material. After irradiation, the irradiated structure can be subjected to a post-exposure treatment prior to development of the latent image (see FIG. 2). Specifically, the post-exposure treatment can include a post-exposure bake and / or a post-exposure delay to age the irradiated structure. In embodiments where a post-exposure bake (PEB) is used, the post-exposure bake can be performed at a temperature of about 45°C to about 250°C, in other embodiments about 50°C to about 225°C, in further embodiments about 60°C to about 200°C, and in other embodiments about 95°C to about 190°C, expressly including any range based on a combination of the lower and upper limits, such as about 95°C to about 250°C, prior to development. The post-exposure bake can generally be performed for at least about 0.1 minutes, in further embodiments about 0.5 minutes to about 30 minutes, and in other embodiments about 0.75 minutes to about 10 minutes. A person of ordinary skill in the art will recognize that additional ranges of post-exposure heating temperatures and times within the explicit ranges above are contemplated and are within the present disclosure. The post-exposure bake (PEB) can be performed by blanketing the wafer in a particular atmosphere, such as air, air containing a modifying gas, N, argon, or other inert gas, or vacuum, as described herein. The high contrast in these material properties further promotes the formation of high-resolution lines with smooth edges in the developed pattern, as described in the following section.

[0028] It may also be desirable to have a post-exposure delay during which the exposed wafer is aged. A post-exposure delay can be used as an alternative to a post-exposure bake (although in some embodiments neither can be used), or the post-exposure delay can be performed before the post-exposure bake, or the post-exposure delay can be performed after the post-exposure bake, or the post-exposure bake can be performed both after the first post-exposure delay and before the second post-exposure bake. If heating is performed during the post-exposure delay, the heating temperature will generally be lower than that of the post-exposure bake, and appropriate temperature ramps will be used to transition between the different heating domains.

[0029] The post-exposure delay can be at least about 10 minutes, in further embodiments at least about 20 minutes, in other embodiments from about 25 minutes to about 7 days, in some embodiments from about 30 minutes to about 3 days, and in other embodiments from about 40 minutes to about 2 days, with additional ranges expressly including any combination of the delay endpoints of these ranges. The post-exposure delay (PED) can be conducted by enclosing the wafer in a specified atmosphere, such as air, air containing a modifying gas, N2, argon, or other inert gas, or vacuum, as described herein. The post-exposure delay can be conducted at ambient temperature or at an elevated temperature, which can accelerate the process time to allow for shorter delays. The temperature during the post-exposure delay, or for selected portions of the post-exposure delay, can be from about 30°C to about 150°C, in other embodiments from about 40°C to about 130°C, in further embodiments from about 50°C to about 120°C, and in some embodiments from about 55°C to about 95°C, as well as expressly including additional ranges based on these temperature endpoints, such as 30°C to 95°C. A person of ordinary skill in the art will recognize that additional ranges of times and temperatures within the explicit ranges above are contemplated and are within the present disclosure. Higher temperatures generally are not maintained for extended periods of time. However, various process parameters can be optimized based on the teachings herein to achieve the desired improvement in patterning.

[0030] Exposure of organometallic resist compositions to radiation generally involves bond cleavage. In resist compositions of particular interest, bond cleavage generally involves the breaking of carbon-metal bonds. Breaking of carbon-metal bonds can liberate reactive species such as radicals and / or metal atoms capable of forming other ligand-metal bonds. Organic species generally form gaseous by-products that are released from the material, and metal oxide-hydroxides condense into more metal oxide-like structures and / or form networks of tightly bonded species that densify, resulting in patterned structures with high etch contrast between irradiated and non-irradiated areas. For example, irradiated and densified coatings become more insoluble in organic solvents used to solubilize the original organometallic composition.

[0031] Post-exposure processing is generally directed to promote and enhance the network formation and densification of the exposed coating. Heating can generally accelerate the solid-state reorganization of the lattice structure, which is generally part of the densification process, and heating can also promote certain reactions. Excessive heating can affect the non-irradiated portions of the coating, thereby reducing development contrast, so heating should be properly controlled. Further aging via a post-exposure delay before development of the latent image can provide additional time for the densification process to occur. During post-coating processing, the atmosphere surrounding the coated wafer can significantly affect the effectiveness of the processing. The atmosphere can be characterized by composition and pressure.

[0032] Because the densification process involves small volume changes, increasing pressure will thermodynamically tend to favor densification. The reverse is generally true, so decreasing pressure will thermodynamically tend to disfavor densification. An example is presented below showing that a vacuum applied during the post-exposure delay results in a decrease in etch contrast. Similarly, the chemistry of the atmosphere can also alter the effectiveness of the post-exposure treatment. Again, suitable gaseous atmospheres include, for example, air, air plus additional gases, nitrogen, argon, and other inert gases, as well as reactive gases. Separately from or in conjunction with a separate post-exposure bake, some heat can be applied during the post-exposure delay, which can be at a higher temperature than the post-exposure delay heating, so as to distinguish the two process regimes.

[0033] In particular, it has also been discovered that it is possible to increase the sensitivity of photoresists by exposing radiation-patterned materials to carbon dioxide. The formation of new compositions resulting from the incorporation of CO into organooxotin hydroxide systems has been described, for example, by Plasseraud et al., J. Organometallic Chem. 2010, Vol. 695, 1618-1626, entitled "Di-n-butyltin oxide as a chemical carbon dioxide capturer," Plasseraud et al., Z. Naturforsch. 2010, Vol. 65b, 1293-1300, entitled "Unprecedented Hexa- and Undecanoclear Frameworks of Two New Tin(IV) Oxo Clusters Resulting from Partial Debenzylation Reactions," and Zheng et al., Chem. Eur. J. 2010, Vol. 10, 3761-3768, entitled "A New System in Organooxotin Cluster Chemistry Incorporating Inorganic and Organic Spacers between Two Ladders Each" No. 4,999,333, issued Dec. 19, 1999, entitled "Containing Five Tin Atoms," all of which are incorporated herein by reference. Without wishing to be bound by theory, the increased speed may occur due to carbonate deficiency or the formation of metal carbonates which have different solubility in the developer solution than carbonate-free materials. For example, metal carbonates and bicarbonates may be reacted by the following reaction: MO + CO2 → MCO3 2M-OH + CO2 → MCO3 + H2O M-OH + CO2 → M-HCO3 2M-OH + CO2 → MO(CO)OM + HO Based on the teachings herein, exposure to CO can occur during one or more process steps between coating deposition and image development, and heat may or may not be applied during exposure to CO.

[0034] The resulting metal carbonate material has lower solubility in the developer solution than virgin material. This results in a lower dose required to pattern the photoresist to the desired feature size. Carbon dioxide is present in air, and its temporal variation over time has been widely discussed in the media recently. The current CO2 content in air is reported to be approximately 415 ppm. During wafer processing, the air can be enriched with an increased CO2 partial pressure (concentration) to favor carbonate formation. Le Châtelier's principle also suggests that reduced humidity favors carbonate formation, but some humidity is desirable for the formation of metal hydroxides, which may enable several carbonate formation pathways. An example using a CO2 concentration of 500 ppm is presented below. Generally, the enhanced CO2 level can be at least about 450 molar ppm, in some embodiments from about 475 ppm to about 10 molar percent, in further embodiments from 500 ppm to about 5 molar percent, and in other embodiments from about 750 molar ppm to about 1 molar percent, as well as any combination of the lower and upper limits of the stated ranges. In some embodiments, the CO2 concentration can range to about 20% or less, in other embodiments, about 10% or less, and in further embodiments, about 5% or less. A person of ordinary skill in the art will recognize that additional ranges of carbon dioxide concentrations within the explicit ranges above are contemplated and are within the present disclosure.

[0035] The above examples using water vapor and carbon dioxide are intended to be illustrative and not limiting. The present invention relates to exposing radiation-patterned materials to reactive gas species to form new non-volatile compositions. Other reactive gases, such as oxygen (O), hydrogen peroxide (H), ozone (O), sulfur dioxide, hydrogen sulfide (HS), carbon monoxide (CO), hydrogen gas (H), nitric oxide (e.g., NO, NO, NO, NO, NO, and NO), methane (CH), ammonia (NH), ethylene oxide (oxirane, cyclic CHO), carbonyl sulfide (OCS), alkyl mercaptans (CHSH), silanes or disilanes (SiH, SiH), and phosphine (PH), are anticipated and contemplated. For processing, these compositions can be diluted with a carrier gas, such as air, dry air, nitrogen, argon, or other inert gases. The overall pressure can fall within the ranges explicitly stated above given for typical processing, e.g., at least about 200 Torr or 600 Torr to 800 Torr, although other pressure ranges herein can be used as well. In terms of the concentration of these reactive gases in the carrier gas, if used, can be from about 100 mole ppm to about 10 mole percent, in further embodiments from about 500 ppm to about 5 mole percent, and in other embodiments from about 0.1 mole percent to about 1 mole percent. A person of ordinary skill in the art will recognize that additional ranges of pressure and concentration within these explicitly stated ranges are contemplated and are within the present disclosure. Examples of organotin oxide hydroxide systems containing other anions are described in Plasseraud et al., Z. Naturforsh. 2011, Vol. 66b, pp. 262-268, entitled "A New Dodecanoclear Organostannoxane," and a review by Chandrasekhar et al., Coord. Chem. Rev. 2002, Vol. 235, pp. 1-52, entitled "Organotin assemblies containing Sn—O bonds," both of which are incorporated herein by reference. Synthetic studies based on alkylstannoic acids do not suggest the methods described herein or the specific scope of the compositions herein.

[0036] Furthermore, the same gas need not be present at every processing point. It may be desirable to have a reactive gas present during some processes but absent during others. The absolute concentration of reactive gas required for optimal results can be discovered through routine experimentation. Furthermore, the absolute concentration of reactive gas can vary for different processes within the processing life of a photoresist. For example, the absolute concentration of CO or water vapor that provides optimal results may differ between the coating process and the bake process for the same coating. Optimal results are also subjective in relation to the requirements for forming a desired integrated device. Additionally, supercritical and hydrothermal conditions during one or more processing steps are contemplated and anticipated by the present invention.

[0037] The gas exposed to the wafer surface can be selected at a particular process point. EUV and electron beam exposure typically use a vacuum for the exposure chamber. The vacuum is typically 1×10 -5 This can be considered a pressure below Torr, and even lower partial pressures may be desired for certain gas components. For UV processing, such as at 254 nm, non-absorbing gas atmospheres can be used, and examples are provided using air or nitrogen atmospheres during irradiation. The gaseous atmosphere surrounding the wafer can be adjusted with other process steps performed before development: a pre-exposure bake, a pre-exposure delay, a post-exposure bake, and a post-exposure delay.

[0038] Regardless of the chemical composition of the atmosphere surrounding the wafer at various process times, the pressure can be adjusted accordingly. The atmospheric pressure at the process facility can serve as a baseline. Because most facilities are above sea level, the actual average atmospheric pressure is less than standard atmospheric pressure and is further subject to temporal variations due to weather. Additionally, ventilation systems can be configured to maintain a slight negative pressure relative to the outside pressure to control the relative flow of gases into and out of the facility. A slight overpressure can be maintained within the process chamber to allow for gas turnover within the chamber. Those skilled in the art will recognize that, from a practical standpoint, pressures between about 600 Torr and about 800 Torr can be considered atmospheric pressure, and that in some embodiments, pressures between 800 Torr and 1200 Torr can be of interest in connection with maintaining a positive flow of the atmosphere in contact with the wafer. Other pressure ranges may be useful in processing. Other ranges of interest include pressures of at least about 200 Torr, and for wafer processing, vacuum or low pressure can be considered any pressure below about 1 Torr. A person of ordinary skill in the art will recognize that additional pressure ranges within the explicit ranges above are contemplated and are within the present disclosure.

[0039] Air can generally be provided by adjusting the temperature and relative humidity, and by adding any additional gas, such as a reactive gas. Therefore, air can be used as a carrier gas for the reactive gas. Similarly, dry air can be used as a carrier gas to control its reactive gas content, and dry air can be considered to have about 0.1 mol% or less of water. The external pressure of the atmosphere can vary depending on altitude and weather. The fabrication facility can maintain the pressure within a desired range using a ventilation device, which can also adjust the relative humidity and partial pressure of any additional gases. If the composition of the gas, other than water, varies by 10% or less relative to air, the gaseous atmosphere can be considered modified air. At elevated temperatures, particularly during the calcination process, water vapor can constitute a significant fraction of the gas. The water vapor can generally be adjusted to have a desired relative humidity.

[0040] Desirable ranges of carbon dioxide and other reactive gases are presented below. Metal oxide hydroxide photoresists, such as organotin photoresists, have been shown to have excellent properties as photoresists used in lithographic optical patterning. Examples of metal oxide hydroxide photoresists include hafnium oxyhydroxide and zirconium oxyhydroxide described in U.S. Patent No. 9,176,377 B2, titled "Patterened Inorganic Layers, Radiation-Patterned Compositions, and Corresponding Methods" by Stowers et al., and U.S. Patent No. 9,281,207 B2, titled "Solution-Processable Hard Masks for High-Resolution Lithography" by Stowers et al. (both incorporated herein by reference). In particular, organotin oxide photoresists have been shown to achieve high resolution and high sensitivity. Preferred organotin oxyhydroxide photoresists include U.S. Patent No. 9,310,684 B2, titled "Organometallic Solution-Based High-Resolution Patterning Composition" by Meyers et al. ('684 patent), U.S. Patent Application Publication No. 2016 / 0116839 A1, titled "Organometallic Solution-Based High-Resolution Patterning Composition and Corresponding Method" by Meyers et al., and U.S. Patent No. 10,228,618 B2, titled "Composition, Precursor, and Patterning for Organotin Oxyhydroxide Patterning" (all of which are incorporated herein by reference). Specifically, organometallic radiation-sensitive resists have been developed based on alkyltin compositions, such as alkyltin oxyhydroxide, represented by the formula R z SnO (2-z / 2-x / 2) (OH) x (where 0 < x < 3, 0 < z ≤ 2, x + z ≤ 4, and R is a hydrocarbyl or organo group that forms a carbon bond with the tin atom). A particularly effective form of these compositions is monoalkyltin oxyhydroxide where z = 1 in the above formula.

[0041] Specifically, R can be a moiety having 1 to 31 carbon atoms, one or more of which may be optionally substituted with one or more heteroatom functional groups, such as groups containing O, N, Si, Ge, Sn, Te, and / or halogen atoms, or an alkyl or cycloalkyl group further functionalized with a phenyl or cyano group. In some embodiments, R can contain ≦10 carbon atoms and can be, for example, methyl, ethyl, propyl, isopropyl, butyl, t-butyl, isobutyl, or t-amyl. The R group can be a linear, branched (i.e., the metal-bonded carbon atom is secondary or tertiary), or cyclic hydrocarbyl group. Each R group individually and generally has 1 to 31 carbon atoms, 3 to 31 carbon atoms in groups with secondary bonded carbon atoms, and 4 to 31 carbon atoms in groups with tertiary bonded carbon atoms. Specifically, R 1 R 2 R 3 CSn(NR')3 (where R 1 and R 2 are independently alkyl groups having 1 to 10 carbon atoms, and R 3 Branched alkyl ligands may be desirable in some patterning compositions, where the compound can be represented as R (where R is hydrogen or an alkyl group having 1 to 10 carbon atoms). As discussed below, this representation of the alkyl ligand R is generally 1 R 2 R 3 The same is applicable to other embodiments having CSn(X)3, where X corresponds to a trialkoxide or triamide moiety. In some embodiments, R 1 and R 2 is capable of forming a cyclic alkyl moiety, and R 3 may also be linked to other groups in the cyclic moiety. Suitable branched alkyl ligands include, for example, isopropyl (R 1 and R 2 is methyl and R 3 is hydrogen), tert-butyl (R 1 , R 2 , and R 3 is methyl), tert-amyl (R 1and R 2 is methyl and R 3 is -CH2CH3), sec-butyl (R 1 is methyl and R 2 is -CH2CH3, and R 3 is hydrogen), neopentyl (R 1 and R 2 is hydrogen and R 3 is —C(CH3)3), cyclohexyl, cyclopentyl, cyclobutyl, and cyclopropyl. Examples of suitable cyclic groups include, for example, 1-adamantyl (—C(CH2)3(CH)3(CH2)3 or tricyclo(3.3.1.13,7)decane attached to the metal at a tertiary carbon) and 2-adamantyl (—CH(CH)2(CH2)4(CH)2(CH2) or tricyclo(3.3.1.13,7)decane attached to the metal at a secondary carbon). In other embodiments, the hydrocarbyl group may include an aryl or alkenyl group, such as a benzyl or allyl group, or an alkynyl group. In other embodiments, the hydrocarbyl ligand R may include any group consisting exclusively of C and H and containing 1 to 31 carbon atoms. In summary, some examples of suitable alkyl groups bonded to tin include, for example, linear or branched alkyl groups (i-Pr((CH3)2CH-), t-Bu((CH3)3C-), Me(CH3-)n-Bu(CH3CH2CH2CH2-)), cyclo-alkyl groups (cyclo-propyl, cyclo-butyl, cyclo-pentyl), olefinic groups (alkenyl, aryl, allyl), or alkynyl groups, or combinations thereof. In further embodiments, suitable R groups may include hydrocarbyl groups substituted with heteroatom functional groups, including cyano, thio, silyl, ether, keto, ester, or halogenated groups, or combinations thereof.

[0042] While alkyltin compositions have demonstrated particularly promising results, other organometallic resist compositions have been explored. See, for example, U.S. Pat. No. 9,176,377 to Stowers et al., entitled "Patterned Inorganic Layers, Radiation-Patterned Compositions, and Corresponding Methods," U.S. Patent Application Publication No. 2013 / 0224652 to Bass et al., entitled "Metal Peroxo Compounds with Organic Coligands for Electron Beam, Deep UV, and Extreme UV Photoresist Applications," and U.S. Patent Application Publication No. 2002 / 0076495 to Maloney et al., entitled "Methods for Making Electronic Materials," all of which are incorporated herein by reference. Other organometallic patterning compositions based on various metals are described in U.S. Pat. No. 9,372,402 B2 to Freedman et al., entitled "Molecular Organometallic Resists for EUV Applications," which is incorporated herein by reference.

[0043] Although coatings can be formed using precursors containing RSnX3 (where X is a hydrolyzable group such as a halide, amide, or alkoxide group), alkyl tin oxide hydroxide compositions can be deposited directly. The precursors can be deposited using solution or vapor-phase coating processes. When these precursors have hydrolyzable ligands, in situ hydrolysis can be performed by carrying out the deposition in the presence of water vapor to directly form (organo)alkyl tin oxide hydroxide coatings.

[0044] Specifically, the formation of the photosensitive metal hydroxide oxide coating can be achieved via various means known to those skilled in the art, such as spin-coating. In some embodiments, the photosensitive organotin coating can be formed via vapor deposition techniques, such as atomic layer deposition (ALD) or chemical vapor deposition (CVD) techniques, as described in U.S. Pat. No. 10,228,618 B2 to Meyers et al., entitled "Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning," and U.S. Pat. No. 9,778,561 B2 to Marks et al., both of which are incorporated herein by reference.

[0045] When using spin-coating as a means of depositing metal oxide hydroxide photoresists, it is desirable to control the presence and concentration of reactive gases within the coating chamber. The above references disclose that water vapor from the ambient air may be required to form the coating. The present invention further discloses a method for controlling humidity within the coating chamber to a specific level to improve the reproducibility of the coating process and to optimize coating uniformity. Additionally, the presence and concentration of other reactive gases or solvent vapors can be controlled to enhance coating reproducibility and / or coating uniformity.

[0046] After the coating is formed, the coated substrate typically undergoes several transfer steps within a wafer track or other equipment. During these transfer steps, it is generally desirable to control the presence and concentration of reactive gases to reduce process variability.

[0047] Generally, metal oxide hydroxide photoresists are stabilized by radiation-sensitive ligands that decompose upon exposure to EUV, UV, or electron beam radiation to generate reactive metal sites (i.e., dangling bonds) within the material that can promote condensation and polymerization reactions, such as those described in reactions 1a, 1b, and 1c above, either immediately upon exposure or in a subsequent processing step, such as a post-exposure bake (PEB). Typically, in negative-tone photoresists, the more condensed and polymerized the metal oxide becomes, the less soluble it becomes in the developer, thereby providing the contrast needed to function as a photoresist.

[0048] Photoresist coatings can generally be patterned using radiation from a suitable source, such as extreme ultraviolet (EUV), ultraviolet (UV), or electron beam (EB) radiation. In the fabrication of semiconductor devices, EUV radiation is generally preferred because it provides higher resolution compared to UV radiation and higher throughput compared to EB radiation. Generally, the radiation can be directed through a mask onto the substrate material or a radiation beam can be controllably scanned across the substrate to form a latent image in the resist coating.

[0049] After exposure to radiation to form a material bearing a radiation-patterned latent image, it is generally desirable to perform a post-exposure bake (PEB). The PEB can be performed at a temperature of from about 45°C to about 250°C in some embodiments, from about 50°C to about 190°C in other embodiments, and from about 60°C to about 175°C in further embodiments. The post-exposure bake can generally be performed for at least about 0.1 minutes, from about 0.5 minutes to about 30 minutes in further embodiments, and from about 0.75 minutes to about 10 minutes in other embodiments. A person of ordinary skill in the art will recognize that additional ranges of PEB temperatures and times within the explicit ranges above are contemplated and are within the present disclosure.

[0050] Due to the properties of metal oxide hydroxide materials, we have discovered that exposure to a reactive gas after radiation patterning can have a significantly greater effect on the material than when the reactive gas is introduced before radiation patterning. Without wishing to be limited by theory, we believe that radiation-patterned materials can react rapidly with reactive gases and reactive intermediates (e.g., metal hydrides) due to the presence of dangling bonds and unfilled coordination spheres within the radiation-patterned material. This effect can be illustrated by comparing the consequences of two different processing delays on the ultimate feature size observed after development of a radiation-patterned coating, as shown in Example 2. Furthermore, developer contrast can be further enhanced by exposing radiation-patterned materials to a reactive gas to promote thermolysis induced by radiolysis of other ligands within the material.

[0051] Therefore, it is generally desirable to expose the radiation-patterned metal oxide hydroxide photoresist to a reactive gas during or after radiation patterning to form the latent image. For example, after exposure to radiation to form the latent image, the reactive gas can be present during a subsequent post-exposure bake (PEB) process. The elevated temperature of the PEB increases the reaction rate between the reactive gas and the exposed areas of the photoresist.

[0052] After exposing the radiation-patterned material to a reactive gas, the material can then be developed with an appropriate developer solution. Useful developer compositions for these organo-tin oxide photoresists are described in U.S. Patent Application Publication No. 2020 / 0326627 to Jiang et al., entitled "Organometallic Photoresist Developer Compositions and Processing Methods," which is incorporated herein by reference. These compositions, which contain both metal oxide hydroxides and organic ligands, have been shown to be capable of achieving both positive-tone and negative-tone patterning in organo-tin oxide hydroxide systems. For example, when an organic solvent is used as the developer, the unexposed material is dissolved away, and the exposed material remains, achieving negative-tone patterning. In contrast, when an aqueous acid or base solution, such as one containing tetraalkylammonium hydroxide, is used as the developer, the exposed material is dissolved away, and the unexposed material remains, achieving positive-tone patterning. In practicing the present invention, it is possible to change the solubility of the material in the selected developer compared to when it remains unreacted with the reactive gas.

[0053] In negative tone imaging, the developer may contain an organic solvent, such as the solvent used to form the precursor solution. Generally, the appropriate developer solvent composition selected may be influenced by the solubility parameters of both the irradiated and non-irradiated coating materials, as well as the developer's volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials. Specifically, suitable developer solvents include, for example, aromatic compounds (e.g., benzene, xylene, toluene), esters (e.g., propylene glycol monomethyl ester acetate, ethyl acetate, ethyl lactate, n-butyl acetate, butyrolactone), alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, isopropanol, 1-propanol, methanol), ketones (e.g., methyl ethyl ketone, acetone, cyclohexanone, 2-heptanone, 2-octanone), ethers (e.g., tetrahydrofuran, dioxane, anisole), and the like. Development can be carried out for about 5 seconds to about 30 minutes, in further embodiments from about 8 seconds to about several minutes, and in other embodiments from about 10 seconds to about 10 minutes. A person of ordinary skill in the art will recognize that additional ranges within the explicit ranges above are contemplated and are within the present disclosure.

[0054] For positive-tone imaging, developers generally can include aqueous acids or bases. In some embodiments, aqueous bases can be used to obtain sharper images. To reduce developer contamination, it may be desirable to use developers that do not contain metal atoms. Therefore, quaternary ammonium hydroxide compositions, such as tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or combinations thereof, are desirable developers. Quaternary ammonium hydroxides of particular interest can generally be represented by the formula R4NOH, where R = methyl, ethyl, propyl, butyl, or combinations thereof. The coating materials described herein can generally be developed with the same developers currently commonly used for polymer resists, specifically tetramethylammonium hydroxide (TMAH). Commercially available TMAH is available at 2.38 weight percent, and this concentration can be used in the processes described herein. Additionally, mixed quaternary tetraalkyl-ammonium hydroxides can be used. Generally, the developers may contain from about 0.5 to about 30 weight percent, and in further embodiments from about 1 to about 25 weight percent, and in other embodiments from about 1.25 to about 20 weight percent of the tetra-alkylammonium hydroxide or similar quaternary ammonium hydroxide. A person of ordinary skill in the art will recognize that additional ranges of developer concentrations within the explicit ranges above are contemplated and are within the present disclosure.

[0055] Development can also be carried out using so-called dry processes. Dry development can include, for example, selective removal of irradiated or non-irradiated areas of a photoresist by exposing the material to an appropriate plasma or flowing gas. Dry development of organometallic resists is described in PCT Publication WO 2020 / 132281 A1 by Volosskiy et al., entitled "Dry Development of Resist," which is incorporated herein by reference. In such dry development processes, development can be achieved by exposing the irradiated substrate to a plasma or thermal process while flowing a gas containing a Lewis acid, such as BCl. In such processes, both negative and positive tone behavior can be achieved by appropriate selection of reactant gases.

[0056] After developing the photoresist to form a patterned coating material, a subsequent anneal can be performed to further solidify and stabilize the patterned features. As with other processing steps, this anneal can be performed in an environment with a specific concentration of a specific reactive gas. It may be desirable to have a reactive gas present in this anneal that was not present in the previous step. Because radiation patterning has already been performed, it is not necessary to preserve the photosensitivity of the material; instead, the material can be converted to a new composition to facilitate further processing, such as etching. For example, a reducing reactive gas, such as carbon monoxide, hydrogen gas, methane, etc., and mixtures thereof, can be present during this anneal to convert at least a portion of the material to a new composition. The reactive gas present in this anneal step can convert at least a portion of the patterned material to a new composition, thereby enabling subsequent etching or other processing. Thus, tailoring subsequent etching or other process steps to interact with the composition formed by reacting the patterned material with a reactive gas can enable post-processing techniques that can reduce or mitigate scumming, microbridging, or other defects.

[0057] The annealing temperature is not particularly limited, so long as the auxiliary layer or auxiliary material can retain their respective properties, such as sufficient etch contrast, and the selected reactive gas or gases are sufficiently reactive. In some embodiments, the annealing temperature can be between 100°C and 500°C, in other embodiments between 200°C and 500°C, and in further embodiments between 300°C and 400°C.

[0058] To aid in evaluating development, wafers can be patterned and pattern formation evaluated as a function of EUV dose. First, consider imaging as a step function of illuminated and unilluminated regions. The patterned structures can be evaluated using automated imaging equipment, typically a scanning electron microscope imager. For example, certain commercially available CD-SEM equipment can measure critical line dimensions (linewidths) and also evaluate defects such as microbridging. In some embodiments, the improved processes described herein can result in an increase in critical dimension using equivalent development, coating formation, and irradiation. In some embodiments, the increase in critical dimension can be at least about 0.25 nm, in further embodiments, at least about 0.50 nm, and in further embodiments, at least about 0.75 nm. Those skilled in the art will recognize that additional ranges of critical dimension increase within the ranges explicitly stated above are contemplated and within the scope of the present disclosure. Viewed from another perspective, the concept of critical dimension can be expressed as a dose-to-size value, which is the radiation dose used to achieve a particular feature size. Therefore, an increase in critical dimension corresponds to a decrease in dose-to-size value.

[0059] After forming the patterned coating material, the coating material can be further processed to facilitate the formation of a selected device. Further, additional material deposition, etching, and / or patterning can typically be performed to complete the structure. The coating material may or may not ultimately be removed. In either case, the quality of the patterned coating material can be improved to form improved devices, such as devices with smaller footprints. If a layer is not removed, the patterned coating (resist) material is incorporated into a structure. In embodiments where the patterned coating (resist) material is incorporated into a structure, the properties of the coating (resist) material can be selected to provide the desired patterning properties as well as the properties of the material within the structure. [Example]

[0060] In each of the following examples, the process flow for each example is generally similar, although each example differs in the timing or atmosphere present. The organotin resist film for each example was prepared by spin-coating an organotin solution of a 20 / 80 molar blend of MeSn(OtAm)3 and tBuSn(OtAm)3 in 4-methyl-2-pentanol onto a silicon wafer.

[0061] Example 1: Effect of reactive gas concentration on processing This example illustrates the effect that the concentration of a reactive gas (in this case carbon dioxide) can have on the patterning performance of an organotin photoresist.

[0062] General Coating and Treatment Processes A silicon wafer with a 10 nm spin-on glass (SOG) layer was used as the substrate. The wafer was coated with approximately 20 nm of organotin photoresist. The wafer was then baked at 100 °C for 60 seconds and exposed to 47.1 mJ / cm2 in an ASML NXE3400 exposure tool. 2The film was exposed to EUV radiation at 170° C. for 60 seconds, developed in 2-heptanone, and subjected to a final bake at 150° C. for 60 seconds.

[0063] Reactive gas treatment Three wafers were processed individually in atmospheres with varying CO2 levels, ranging from a low of 354 ppm to a high of 506 ppm. The atmosphere composition remained constant throughout the processing for each individual wafer, except for the exposure period, which was performed under vacuum. Line-and-space patterns with 18 nm feature sizes on a 36 nm pitch were analyzed on a Hitachi CG5000 CD-SEM, which uses image analysis for automated evaluation of critical dimensions.

[0064] Figure 3 shows the difference in feature size, or critical dimension (CD), at different CO concentrations during processing. Low concentrations of CO, approximately 350 ppm to 400 ppm, resulted in smaller CDs than wafers processed in the presence of higher levels of CO, and wafers processed in the presence of moderate concentrations of CO resulted in smaller CDs than wafers processed in the presence of even higher concentrations of CO. This example is illustrative for two reasons: 1) the presence of a sufficient concentration of reactive gas results in larger feature sizes at a given dose (i.e., the presence of a sufficient concentration of reactive gas can result in a lower processing dose for a desired feature size), and 2) it is desirable to control the concentration of reactive gas in the processing atmosphere so that wafer-to-wafer reproducibility is sufficient. Samples were processed at a constant dose of 47 mJ and constant process conditions. The larger CDs obtained at a constant dose suggest that a lower dose may be employed to achieve a particular desired result.

[0065] The results show an inverse correlation between the CO2 concentration during processing and the dose required to image a given feature size. The change in CD was approximately 0.9 nm for an increase of approximately 150 ppm in the average CO2 concentration. These results suggest that controlled increases in the concentration of reactive gases such as CO2 in the processing environment can result in improved patterning performance compared to standard processing.

[0066] Example 2: Effects of processing delays This example illustrates the effect of process delay control on the patterning performance of organotin photoresists.

[0067] Two sets of wafers were coated, each set subjected to a delay at a different point in the process, and processed as described in the general coating and processing steps in Example 1. One set of wafers was processed using various post-coating delays (PCDs), where the substrate was coated and each wafer was held in ambient air for a different amount of time, represented as a delay. The post-coating delay (PCD) samples are shown in Figure 4 with an "X" data label. The second set of wafers was processed normally via radiation patterning using EUV radiation, and then various post-exposure delays (PEDs), where each wafer was held in ambient air for a different amount of time (delay) before post-exposure baking. The post-exposure delay (PED) samples are shown in Figure 4 with a circle data label. Both sets of wafers were finally developed, hard-baked, and analyzed via procedures similar to those described in Example 1.

[0068] It can be seen from Figure 4 that the wafers subjected to PED delay underwent a larger shift in CD in a significantly shorter time than the wafers subjected to PCD. As described herein above, the faster CD response to post-exposure delay is evidence of a higher reaction rate for the coated wafers, which may involve the interaction of the radiation-patterned material with reactive gases in the ambient atmosphere, which may include nitrogen, oxygen, carbon dioxide, water vapor, etc. This result suggests that delay control in the presence of an appropriate processing environment can result in improved patterning performance compared to standard processing, and that this effect is more pronounced with post-exposure delay than with post-coat delay.

[0069] Example 3: Effect of ambient atmosphere during exposure This example illustrates the effect that radiation exposure in a nitrogen atmosphere versus an air atmosphere can have on the patterning performance of organotin photoresist. Thin films for contrast curves were deposited on silicon wafers (150 mm diameter) with native oxide surfaces. Wafer stacks were fabricated by first depositing approximately 60 nm of bottom antireflective coating (BARC) (DUV46M, Brewer Science) by spin-coating at 1300 rpm, followed by approximately 20 nm of organotin photoresist by spin-coating an organotin solution at 1000 rpm. The wafers were then baked at 100°C for 2 minutes. As shown in Figure 5, the patterning performance was measured using an in-house UV exposure system configured for 4.7 mW / cm². 2 The 254 nm radiation exposure was performed for 3 minutes using a UVP UV transluminator operating at a laser power of 1000 Hz. Figure 5 illustrates an in-house UV exposure system 200 with a UV source 202, which is a UVP UV transluminator, on top of which is an absorbing material 204, a 0.03 mm film of polyethylene, on top of which is a fused silica diffuser plate 208, on top of which is a half-tone mask 212. The half-tone mask 212 contained a 10 x 10 array of various transmissive pads capable of delivering a corresponding dose array to the resist. The half-tone mask 212 is separated from the resist 216 by a small air gap of 0.28 mm. In this example, the substrate 220 was a silicon wafer. The UV exposure system 200 was set up in a Cleatech isolation glovebox equipped with an inlet for nitrogen gas, which also allows for air operation. To create a nitrogen atmosphere, the glovebox was purged by flowing enough N until the internal relative humidity was below 5%. The wafers were then loaded into the glove box, and the box was purged again until the relative humidity stabilized at less than 5%. The second purge was approximately 1 hour in duration with the wafers in the glove box. Wafers prepared for exposure in air were similarly delayed in an air atmosphere for approximately 1 hour before exposure.

[0070] After exposure, the wafer was baked at 170° C. for 2 minutes, developed in a 2-heptanone / acetic acid solution, followed by a 2-heptanone / acetic acid rinse, and then subjected to a final bake at 170° C. for 2 minutes.

[0071] A set of three wafers (A2, A3, A4) were exposed to radiation in ambient air. A set of five wafers (A5-A9) were exposed to radiation in the nitrogen atmosphere described above. Contrast curve data for the two sets of wafers is shown in Figure 6. It can be seen that the wafers exposed to radiation in the nitrogen atmosphere exhibited contrast at a lower dose than the wafers exposed to radiation in the air atmosphere. The results suggest increased resist sensitivity for resists exposed under ambient nitrogen compared to resists exposed under ambient air.

[0072] Example 4: Effect of ambient atmosphere on aging This example illustrates the effect that radiation exposure in a nitrogen atmosphere versus an air atmosphere can have on the patterning performance of organotin photoresists after aging.

[0073] Thin films for contrast curves were deposited on lightly doped silicon wafers (150 mm diameter). Approximately 22 nm films of organotin photoresist were deposited on the wafers. The wafers were then subjected to a post-application bake (PAB) at 100°C for 2 minutes and exposed to 254 nm radiation for 3 minutes, as described in Example 3. The irradiated wafers were not subjected to further processing, such as post-exposure baking, development, or soft baking.

[0074] As shown in Table 1, two wafers (F2 and F3) were coated in air, then transferred to a nitrogen-filled glove box as described in Example 3, held for a selected delay time before exposure after a post-application bake (PAB), and then exposed to 254 nm radiation in a nitrogen atmosphere below 5% RH. Two wafers (F4 and F5) were held in ambient air for a selected delay time after PAB and then exposed to 254 nm radiation in ambient air. Each sample was analyzed by FTIR after a first delay time (t=1) between radiation exposure and FTIR analysis. Samples F2 and F4 were further analyzed by FTIR after a second and third delay time (t=2 and t=3), respectively, between radiation exposure and FTIR analysis. All delays between radiation exposure and FTIR were performed in ambient air.

[0075] [Table 1]

[0076] Figure 7 shows the CH absorbance area measured from the FTIR spectrum of each sample after a delay of t=1 as a function of pad number. Dose increases with pad number. The results indicate that wafers exposed to radiation in ambient air required a higher radiation dose to exhibit the same CH area reduction as wafers exposed to radiation in a nitrogen atmosphere. In other words, exposure in a nitrogen atmosphere resulted in a greater reduction in the alkyl ligand signal than exposure in an air atmosphere. Varying delay times between PAB and exposure did not significantly affect the measured CH area. The results are consistent with the contrast curve results in Example 3, which showed the effect of nitrogen atmosphere on dose versus gel. The results suggest increased resist sensitivity for resists exposed to radiation in a nitrogen atmosphere compared to resists exposed to radiation in ambient air. The increased sensitivity is likely related to faster dealkylation of the resist exposed in nitrogen.

[0077] Figure 8 shows the CH peak area measured from the FTIR spectra of samples F2 and F4 as a function of pad number and delay (aging) time (t=1, t=2, or t=3) between radiation exposure and FTIR analysis. All samples were subjected to a post-exposure delay in air. The results show that the CH area of ​​both samples further decreased after delays t=2 and t=3. For a given pad number, the F4 sample exposed in ambient air showed a similar magnitude of change in CH area due to aging in air compared to the F2 sample exposed under nitrogen. This indicates that aging each sample in air resulted in a reduction of alkyl ligands. The results demonstrate the effect of radiation atmosphere on the aging of photoresist coatings and suggest that more sensitive resists may result from radiation exposure in a nitrogen atmosphere.

[0078] Example 5: Effect of ambient atmosphere after radiation exposure This example illustrates the effect that retardation control in air versus vacuum atmosphere can have on the patterning performance of organotin photoresists after EUV exposure.

[0079] Thin films for contrast curves were deposited on a set of silicon wafers with native oxide surfaces. Approximately 22 nm of organotin photoresist coating was deposited on the wafers. The wafers were then subjected to a post-application bake (PAB) at 100°C for 60 seconds and exposed to EUV radiation using an Energetiq Electrodeless Z-Pinch™ EUV Light Source EQ-10R. One wafer was subjected to a post-exposure delay (PED) in air for 24 hours, another to PED in vacuum for 24 hours, and one was processed without PED. The samples were then baked at 170°C for 60 seconds, developed in 2-heptanone, and finally baked at 250°C for 60 seconds.

[0080] One wafer was subjected to a post-exposure delay by holding the wafer in an ambient air atmosphere for 24 hours after EUV exposure and before subsequent baking. This sample is shown as the leftmost curve in Figure 9 (24 hr PED in air). Another wafer was subjected to a post-exposure delay for 24 hours in vacuum. This sample is shown as the middle curve in Figure 9 (24 hr PED in vacuum). Finally, one wafer was not subjected to a post-exposure delay. This sample is shown as the rightmost curve in Figure 9 (no PED).

[0081] The contrast curve data in Figure 9 show that a post-exposure delay generally reduces dose-to-gel. The results also show that the atmosphere in which PED is performed also affects dose-to-gel. Wafers subjected to a post-exposure delay in air exhibited higher radiation sensitivity.

[0082] FTIR analysis was also performed on these wafers, measuring the region centered at 3220 cm-1, corresponding to OH absorption. The results are presented in Figure 10. OH absorption is normalized to the OH absorption of the as-deposited film before exposure (dose = 0). The data clearly show that significantly more OH is present in the wafers subjected to PED in air. The samples held in air or vacuum for 1 day show higher normalized OH absorbance in the pre-exposure data, suggesting the presence of water absorbed during the delay. The data further show that the exposed material has increased OH absorbance after the air delay compared to the samples held in vacuum or without the delay. The data suggest that the irradiated material, after the air delay, can absorb relatively more HO from the ambient environment to form interstitial water and / or hydroxide ligands, resulting in insolubility of the irradiated regions and thus reducing the dose required to pattern the material, as shown in the contrast curves in Figure 9.

[0083] The results suggest that patterning of lines with the desired CD can be achieved at a given dose in the absence of an air delay, or alternatively at a lower dose with an air delay. In other words, an air delay before exposure can result in a reduction in dose versus size for the desired CD.

[0084] Example 6: Effect of retardation control after radiation exposure This example illustrates the effect that a controlled post-exposure retardation in an air atmosphere can have on the patterning performance of organotin photoresists.

[0085] Thin films for contrast curves were deposited on three silicon wafers (300 mm diameter) with native oxide surfaces. Approximately 22 nm of organotin photoresist coating was deposited on the wafers. The wafers were then subjected to a post-application bake (PAB) at 100°C for 60 seconds and then exposed in an ASML NXE3400 exposure tool for contrast curves. Each of the three wafers was subjected to the post-exposure delay and bake protocol shown in Table 2. The post-exposure delay was performed in air. The samples were then developed in 2-heptanone.

[0086] [Table 2]

[0087] Figure 11 shows the contrast curves for wafers a-c. Comparing the dose-to-gel ratio for wafer c to that for wafer a shows that the PED sample had a lower dose-to-gel ratio, suggesting that significant reaction with atmospheric HO and / or CO occurred, rendering the irradiated areas more insoluble. Comparing the dose-to-gel ratio for wafer b to that for wafer a shows that the 3-day PED sample had a lower dose-to-gel ratio than the 160°C PEB sample. The results suggest that a post-exposure delay can be used to increase resist speed and, in some cases, to replace a post-exposure bake.

[0088] The foregoing embodiments are intended to be illustrative and not limiting. Other embodiments are within the scope of the following claims. Additionally, while the present invention has been described with reference to specific embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the spirit and scope of the present invention. Any incorporation by reference of the foregoing documents is limited to not incorporating subject matter contrary to the explicit disclosure herein. Unless otherwise expressly stated, to the extent that specific structures, compositions, and / or processes are described herein with components, elements, ingredients, or other moieties, the disclosure herein should be understood to cover specific embodiments, embodiments that include specific components, elements, ingredients, other moieties, or combinations thereof, as well as embodiments that consist essentially of such specific components, elements, ingredients, or other moieties, or combinations thereof, which may include additional features that do not alter the fundamental nature of the subject matter proposed in the discussion. The use of the term "about" herein refers to the degree of error of measurement for a particular parameter, unless expressly indicated otherwise. (Aspect 1) A method for improving the processing of an organotin-based coating that can be patterned with radiation having a thickness of about 1 nm to about 500 nm on a wafer, the method comprising: After irradiation and before pattern development, storing the wafer having the coating in an atmosphere at a pressure of at least about 200 Torr for aging, the aging being at least about 20 minutes. (Aspect 2) The organotin-based coating that can be patterned with the radiation comprises a composition represented by the formula RSnO (1.5-(x / 2)) (OH) x (where 0 < x ≦ 3), R is an organic ligand having 1 to 31 carbon atoms, the carbon atoms being bonded to Sn, and one or more carbon atoms being optionally substituted with one or more heteroatom functional groups. The method according to Aspect 1. (Aspect 3) The method according to Aspect 1 or Aspect 2, wherein the atmosphere contains nitrogen and the pressure is at least about 600 Torr. (Aspect 4) The method according to Aspect 1 or Aspect 2, wherein the atmosphere contains air, carbon dioxide, or a combination thereof, and the air has a relative humidity of about 40% to 90%. (Aspect 5) The method according to Aspect 4, wherein the relative humidity varies at about 10% or less. (Aspect 6) The method according to any one of Aspects 1 to 5, wherein storing is carried out to age the wafer for at least about 40 minutes at a pressure of at least about 600 Torr. (Aspect 7) The method according to any one of Aspects 1 to 6, wherein the wafer is heated at a temperature of about 30 °C to about 150 °C during aging. (Aspect 8) The method according to any one of Aspects 1 to 7, wherein the wafer is heated at a temperature of about 95 °C to about 250 °C for 0.1 minute to 10 minutes before aging. (Aspect 9) The method according to any one of Aspects 1 to 8, wherein the wafer is heated at a temperature of about 95 °C to about 250 °C for 0.1 minute to 10 minutes after aging. (Aspect 10) The method according to Aspect 9, wherein the wafer is heated at a temperature of about 45 °C to about 150 °C during aging. (Aspect 11) A method for forming an organotin-based coating that can be patterned with radiation having an average thickness of about 1 nm to about 500 nm on a wafer, the method comprising: Before development of forming a physical pattern, the wafer having the coating and about 500 ppm to about 10 mole percent of CO 2 comprising contacting with an atmosphere containing a concentration, wherein the coating is of the formula RSnO x OH 3-x (where R is an organic ligand having 1 to 31 carbon atoms, the carbon atoms being bonded to Sn, and one or more of the carbon atoms being optionally substituted with one or more heteroatom functional groups), a method. (Aspect 12) The method according to aspect 11, further comprising irradiating the coating with radiation having a pattern corresponding to the physical pattern before contacting the wafer having the coating. (Aspect 13) The method according to aspect 12, further comprising heating the wafer at a temperature of about 45°C to 250°C after irradiation and before development. (Aspect 14) The method according to aspect 13, wherein the heating is carried out after aging and in an atmosphere containing air, carbon dioxide, nitrogen, other reactive gases, or a combination thereof. (Aspect 15) The method according to aspect 13, wherein the heating is carried out before aging and in an atmosphere containing air, carbon dioxide, nitrogen, other reactive gases, or a combination thereof. (Aspect 16) The method according to any one of aspects 11 to 15, wherein the atmosphere is at a temperature of about 45°C to about 150°C during the contacting step. (Aspect 17) The method according to any one of aspects 11 to 16, wherein contacting the wafer with the coating has a duration of at least 20 minutes. (Aspect 18) The method according to any one of aspects 11 to 17, wherein contacting the wafer with the coating is under an atmosphere having a CO 2 concentration of about 600 ppm to about 1 mole percent. (Aspect 19) The organotin-based coating that can be patterned with the radiation comprises a composition represented by the formula RSnO (1.5-(x / 2)) (OH) x (where 0 < x ≦ 3), R is an organic ligand having 1 to 31 carbon atoms, the carbon atoms being bonded to Sn, and one or more of the carbon atoms being optionally substituted with one or more heteroatom functional groups, the method according to any one of aspects 11 to 18. (Aspect 20) The method according to any one of aspects 11 to 19, wherein contacting the wafer with the coating has a duration of at least about 40 minutes at a pressure of at least about 600 Torr. (Aspect 21) A method for improving the processing of a radiation-patternable organotin-based coating comprising organotin oxyhydroxide having Sn-C bonds, wherein the coating has a thickness of about 1 nm to about 500 nm, and the method comprises after irradiation, contacting the wafer having the organotin oxyhydroxide coating with an atmosphere containing a reactive gas to change the tin-binding ligand in the irradiated area, wherein the reactive gas is SO 2 、H 2 S, CH 3 SH, CO, COS, HOOH, NH 3 、H 2 、O 3 , nitrogen oxides, PH 3, SiH 4 , CH 4 , ethylene oxide, or a combination thereof. (Aspect 22) The radiation-patternable organotin oxyhydroxide coating comprises a composition represented by the formula RSnO (1.5-(x / 2)) (OH) x (where 0 < x ≦ 3), R is an organic ligand having 1 to 31 carbon atoms, the carbon atoms are bonded to Sn, and one or more carbon atoms are optionally substituted with one or more heteroatom functional groups, according to the method of Aspect 21. (Aspect 23) The contacting step is carried out at a temperature of about 45 °C to about 250 °C after irradiation and before development, according to the method of Aspect 21 or Aspect 22. (Aspect 24) The contacting step is carried out at a temperature of about 45 °C to about 150 °C for at least about 20 minutes, according to the method of any one of Aspects 21 to 23. (Aspect 25) The contacting step results in an increase in the critical dimension of the developed structure of at least about 0.25 nm, according to the method of any one of Aspects 21 to 24. (Aspect 26) The atmosphere contains a reactive gas at a concentration of about 500 ppm to about 5 mol%, and the pressure of the atmosphere is at least about 600 Torr, according to the method of any one of Aspects 21 to 25. (Aspect 27) The remainder of the atmosphere is air having a relative humidity of 40% to 60%, according to the method of Aspect 26. (Aspect 28) The remainder of the atmosphere is nitrogen, according to the method of Aspect 26. (Aspect 29) A method for improving the processing of a radiation-patternable organotin-based coating comprising organotin oxyhydroxide having Sn-C bonds, wherein the coating has a thickness of about 1 nm to about 500 nm on a wafer, and the method comprises contacting the organotin oxyhydroxide coating with an atmosphere containing a reactive gas, wherein the reactive gas is SO 2 、H 2 S, CH 3 SH, CO, COS, H 2 、O 3 , nitrogen oxides, PH 3 , SiH 4 , HOOH, NH 3 , CH 4 or contains ethylene oxide, and the reactive gas differentially changes the tin-binding ligands of the irradiated and non-irradiated portions of the coating such that a latent image formed by radiation exposure results in a greater contrast in development rate between the irradiated and non-irradiated portions of the coating, method. (Aspect 30) The radiation-patternable organo-tin oxyhydroxide coating contains a composition represented by the formula RSnO (1.5-(x / 2)) (OH) x (where 0 < x ≦ 3), R is an organic ligand having 1 to 31 carbon atoms, the carbon atoms being bonded to Sn, and one or more of the carbon atoms being optionally substituted with one or more heteroatom functional groups, the method according to aspect 29. (Aspect 31) The contacting step is carried out at a temperature of from about 45 °C to about 250 °C after irradiation and before development, the method according to aspect 29. (Aspect 32) The contacting step is carried out at a temperature of from about 45 °C to about 150 °C for at least about 20 minutes, the method according to aspect 29 or aspect 30. (Aspect 33) The contacting step results in an increase in the critical dimension of the developed structure of at least about 0.25 nm, the method according to any one of aspects 29 to 32. (Aspect 34) The atmosphere contains a reactive gas at a concentration of from about 500 mol ppm to about 5 mol percent, and the pressure of the atmosphere is at least about 600 Torr, the method according to any one of aspects 29 to 33. (Aspect 35) The balance of the atmosphere is air having a relative humidity of 40% to 60%, the method according to aspect 34. (Aspect 36) The balance of the atmosphere is nitrogen, the method according to aspect 34.

Claims

1. 1. A method for improving the processing of a radiation-patternable organotin-based coating on a wafer, the coating having an average thickness of 1 nm to 500 nm, the method comprising: holding the wafer with the coating for a predetermined time after irradiation and before pattern development for aging, the holding being carried out in an atmosphere at a pressure of 200 Torr or more for 20 minutes or more; before or after said holding, a post-exposure bake is carried out at a temperature higher than the temperature selected for said holding; and The method wherein the radiation-patternable organotin-based coating comprises an organotin oxide hydroxide having Sn—C bonds.

2. The radiation-patternable organotin-based coating has the formula RSnO （１．５－（ｘ／２）） (OH) ｘ wherein 0<x≦3, 2. The method of claim 1, wherein R is an organic ligand having 1 to 31 carbon atoms, the carbon atoms being bonded to Sn, and one or more carbon atoms optionally being substituted with one or more heteroatom functional groups.

3. 3. The method of claim 1, wherein the atmosphere comprises nitrogen and the pressure is 600 Torr or greater.

4. 3. The method of claim 1 or claim 2, wherein the atmosphere comprises air, carbon dioxide, or a combination thereof, and the air has a relative humidity of 40% to 90%.

5. 5. The method of claim 4, wherein the relative humidity fluctuates by no more than 10%.

6. The method of any one of claims 1 to 5, wherein the holding is carried out at a pressure of 600 Torr or more for 40 minutes or more.

7. The method of any one of claims 1 to 6, wherein the wafer is heated at a temperature between 30°C and 150°C during said holding.

8. The method of any one of claims 1 to 7, wherein the post-exposure bake is carried out at a temperature of from 95°C to 250°C for from 0.1 minutes to 10 minutes before the hold.

9. The method of any one of claims 1 to 8, wherein the post-exposure bake is carried out after the hold at a temperature of from 95°C to 250°C for from 0.1 minutes to 10 minutes.

10. 10. The method of claim 9, wherein the wafer is heated at a temperature between 45°C and 150°C during the holding.

11. 11. The method according to any one of claims 1 to 10, wherein the atmosphere has a carbon dioxide concentration that varies by no more than 20%.

12. 12. The method of any one of claims 1 to 11, wherein the atmosphere comprises from 475 ppm to 10 mole percent carbon dioxide.

13. The method according to any one of claims 1 to 11, wherein said keeping is carried out in an ambient air atmosphere for a period of between 30 minutes and 3 days.

14. 14. The method of any one of claims 1 to 13, wherein said holding forms a physical pattern after said pattern development having increased critical dimensions at a given exposure dose compared to a corresponding wafer not subjected to a holding step.

15. 15. The method of claim 14, wherein the increased critical dimension is 0.25 nm or greater.

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