Additives for metal oxide photoresists, positive tone development with additives, and double bake double development processes

Abstract

A method for patterning a radiation-sensitive material on a substrate includes developing a material on the substrate based on a latent image in the material having irradiated and unirradiated regions to form a physically patterned material on the substrate, the material including an organotin radiation-sensitive patterning material and an additive. The additive is a photoacid generator, a quencher, or a mixture thereof. Improved patterning can be achieved using a series of baking and developing steps, followed by a second baking at a higher temperature, and a second developing step after the second baking step. A precursor solution for forming an organometallic radiation patterning material can include an organic solvent, a dissolved organotin composition having a C-Sn bond cleavable in response to EUV radiation, and a quencher. The additive can include an onium cation.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to co-pending U.S. Provisional Patent Application No. 63 / 398,723 to Kasahara et al., filed August 17, 2022, entitled "Electron Trapping Agents for Metal Oxide Photoresists," which is incorporated herein by reference.

[0002] The present invention relates to organometallic, particularly organotin, patterning compositions that contain additives such as photoacid generators and / or quenchers to improve development process conditions. Specifically, the additives can improve positive-tone imaging, especially by widening the radiation dose-related process window. Development procedures involving successive bake-develop-bake-develop sequences are described that can benefit from the presence of the additives. [Background technology]

[0003] Semiconductor lithography is a complex and critical technology used to fabricate countless diverse devices that have dominated and transformed the modern world since the early 20th century. Semiconductor lithography processes are typically iterative processes involving repeated deposition, patterning, and etching steps of multiple layers and materials to form the desired device. As technology advances and new demands and requirements are placed on each generation of device, there is an increasing need to develop processes and materials that can meet these demands. One of the key materials used in semiconductor lithography processes is photoresist, where an initial pattern is formed by exposure to radiation and subsequently transferred to the underlying substrate.

[0004] Organometallic photoresists have shown promise for use in current and next-generation semiconductor lithography processes due to their high resolution, high etch resistance, and ability to form high-fidelity patterns. These organometallic systems generally function through the formation of condensed oxide networks mediated by radiation exposure, promoting contrast between irradiated (i.e., exposed) and unirradiated (i.e., non-exposed) regions of the material. A development process can then be used to selectively remove irradiated or unirradiated material, thereby achieving a physical pattern of the material based on the pattern of radiation. Summary of the Invention [Problem to be solved by the invention]

[0005] Due in part to their high absorbance of extreme ultraviolet (EUV) radiation and their tendency to form oxide / hydroxide networks, organometallic resists are able to absorb stray photons in nominally unirradiated (i.e., unexposed) areas from "shot noise" phenomena and the like that can cause unwanted photochemistry in those areas, thus resulting in defects such as scum or microbridging between features. The present invention describes improved organometallic photoresist compositions that include electron scavengers to reduce defect formation and improve patterning performance. [Means for solving the problem]

[0006] One aspect of the present invention relates to a precursor composition that includes one or more organotin compositions, an electron scavenger, and a solvent.

[0007] Another aspect of the present invention relates to a radiation-patternable film comprising an organotin species and an electron scavenger.

[0008] Another aspect of the present invention relates to a structure comprising a patternable radiation-sensitive layer comprising an organotin species and an electron scavenger.

[0009] Another aspect of the present invention relates to a method for patterning a structure comprising a radiation-sensitive layer containing an organotin species and an electron scavenger.

[0010] In certain aspects, the present invention relates to a method for patterning a radiation-sensitive material on a substrate, the method comprising developing the material on the substrate based on a latent image in the material having irradiated and non-irradiated regions to form a physically patterned material on the substrate. Development can include contacting the material with an aqueous alkaline liquid, and the material before irradiation is R n SnO x (OH) 4-n-2x , where 0.5 ≦ n < 3, 0 < x < 1.5 (where R includes a hydrocarbyl ligand having 1 to 31 carbon atoms), and an additive (A) in an A:Sn molar ratio of about 0.002 to about 2. The additive includes a photoacid generator, a quencher, or a mixture thereof, and the additive includes an onium ion or a zwitterion. Development includes selective removal of the irradiated regions.

[0011] In a further aspect, the present invention relates to a method for patterning a radiation-sensitive material on a substrate, the method comprising a) developing the material on the substrate based on a latent image in the material having irradiated and non-irradiated regions to form a physically patterned material on the substrate, wherein development includes contacting the material with a first liquid developer, the material before irradiation is R n SnO x (OH) 4-n-2x , where 0.5 ≦ n < 3, 0 < x < 1.5, the substrate having the latent image is subjected to a post-exposure bake at a first temperature of at least about 45 °C, and development includes selectively removing the irradiated or non-irradiated regions to form a first patterned structure, b) heating the first patterned structure at a second temperature at least about 5 °C higher than the first temperature for at least about 0.1 minutes to form a second baked structure, c) Developing the second bake structure, including contact with a second liquid developer, wherein the second liquid developer contains an acid or a base and includes.

[0012] In another aspect, the present invention relates to a precursor solution for forming an organometallic radiation patterning material, the precursor solution comprising an organic solvent, a dissolved organotin composition having a C-Sn bond that can be cleaved in response to EUV radiation, and a quencher, wherein the precursor solution has a tin concentration of about 0.001M to about 1M and a quencher (A) with an A:Sn molar ratio of about 0.002 to about 2, and the quencher contains an onium cation and an anion that is a conjugate base to a weak acid.

[0013] In another aspect, the present invention relates to a radiation-patternable structure comprising a substrate and a radiation-sensitive material on the substrate. The radiation-sensitive material comprises a composition represented by the formula R n SnO x (OH) 4-n-2x , where 0.5 ≦ n < 3 and 0 < x < 1.5, and a quencher (A) in an A:Sn molar ratio of about 0.002 to about 2. The quencher generally contains an onium cation and an anion that is a conjugate base to a weak acid.

Brief Description of the Drawings

[0014] [Figure 1A] It is a schematic side view of an exposure process using a photomask, and the mask forms an aerial image of photons delivered to the surface of the photoresist. [Figure 1B] It is a top-down schematic diagram of the photon distribution across the surface of the photoresist according to the mask pattern. [Figure 1C] It is a schematic side view of the density distribution of photons of a latent image according to the mask pattern. [Figure 2A] It is a schematic plot of the solubility of the photoresist over the pattern dimensions, juxtaposed on the intended line / space pattern of the mask pattern. [Figure 2B]FIG. 2B is a modified example of the plot of FIG. 2A showing the solubility of photoresist by organic developers across the pattern dimensions juxtaposed on the intended line / space pattern of the mask pattern, highlighting areas of the pattern that may result in unintended insolubility in the dark areas of the pattern. [Figure 2C] FIG. 2B is a modified example of the plot of FIG. 2A showing the solubility of photoresist in alkaline developer across the pattern dimensions juxtaposed on the intended line / space pattern of the mask pattern, highlighting areas of the pattern that may result in unintended insolubility in the exposed areas of the pattern. [Figure 3] FIG. 1 is a schematic diagram of a contrast curve for positive tone patterning showing polarity dominated and density dominated regions. [Figure 4] 1 is a diagram of a first contrast curve (solid line) and a second contrast curve (dashed line), where the second contrast curve has a wider solubility window. [Figure 5] 1 is a diagram of the low-dose region of a first contrast curve (dashed line) and a second contrast curve (solid line), where the second contrast curve shows a shift to lower lytic doses than the first contrast curve, as indicated by the arrows. [Figure 6] 1 is a diagram of the high-dose region of a first contrast curve (dashed line) and a second contrast curve (solid line), where the second contrast curve shows a shift to higher lytic doses than the first contrast curve, as indicated by the arrows. [Figure 7] 1 is a diagram of a first contrast curve (dashed line) and a second contrast curve (solid line), where the second contrast curve has an expanded process window for positive tone patterning. [Figure 8] FIG. 1 is a diagram of the change in contrast curve in low-dose and high-dose regions due to the use of a double-bake-double-develop (DBDD) process. [Figure 9]FIG. 1 shows the high dose region of a first contrast curve after a single bake and single develop, and the high dose region of a second contrast curve after a double bake double develop (DBDD) process. [Figure 10A] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A1 additive, each sample subjected to a 120° C. PEB. [Figure 10B] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A1 additive, each sample subjected to a 140° C. PEB. [Figure 10C] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A1 additive, each sample subjected to a 160° C. PEB. [Figure 10D] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A1 additive, each sample subjected to a 180° C. PEB. [Figure 10E] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A1 additive, each sample subjected to a 200° C. PEB. [Figure 10F] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A1 additive, along with a control sample without additive, each sample subjected to a 180° C. PEB. [Figure 11A] FIG. 10 is a set of contrast curves for photoresist samples prepared with A4 additive and subjected to various PEB temperatures from 120°C to 180°C. [Figure 11B] A4 shows the contrast curves for photoresist samples prepared with and without additives, each subjected to PEB at 140°C. [Figure 11C] A4 shows the contrast curves for photoresist samples prepared with and without additives, each subjected to PEB at 160°C. [Figure 11D] A4 shows the contrast curves of photoresist samples prepared with and without additives, each subjected to PEB at 180°C. [Figure 12] 1 is a plot of normalized alkyl content as a function of dose for two photoresist samples prepared with A4 additive and one photoresist sample prepared without the additive, where the sample in the left plot was subjected to a 160° C. PEB and the sample in the right plot was subjected to a 180° C. PEB. [Figure 13A] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A2 additive, each sample subjected to a 120° C. PEB. [Figure 13B] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A2 additive, each sample subjected to a 140° C. PEB. [Figure 13C] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A2 additive, each sample subjected to a 160° C. PEB. [Figure 13D] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A2 additive, each sample subjected to a 180° C. PEB. [Figure 13E] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A2 additive, each sample subjected to a 200° C. PEB. [Figure 13F] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A2 additive, along with a control sample without additive, each sample subjected to a 180° C. PEB. [Figure 14A] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A3 additive, each sample subjected to a 120° C. PEB. [Figure 14B] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A3 additive, each sample subjected to a 140° C. PEB. [Figure 14C] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A3 additive, each sample subjected to a 160° C. PEB. [Figure 14D] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A3 additive, each sample subjected to a 180° C. PEB. [Figure 14E] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A3 additive, each sample subjected to a 200° C. PEB. [Figure 14F] 1 is a set of contrast curves for photoresist samples prepared with various concentrations of A3 additive, along with a control sample without additive, each sample subjected to a 180° C. PEB. [Figure 15] 1 is a set of contrast curves for photoresist samples prepared without additives and subjected to either a single PEB and develop process or a double bake and double develop (DBDD) process. The DBDD process samples were processed at various first PEB temperatures and a constant second PEB temperature. [Figure 16] 1 is a set of contrast curves for photoresist samples prepared with Additive A2 and subjected to either a single PEB and develop process or a double bake and double develop (DBDD) process. The samples subjected to the DBDD process were processed at the same first PEB temperature and a different second PEB temperature. Also shown is the contrast curve for a photoresist sample prepared without the additive and subjected to a single PEB and develop process. [Figure 17]1 shows a set of CD-SEM images of contact holes patterned in either a photoresist sample without additive or a photoresist sample with additive A2, each sample subjected to either a 160°C PEB or a 180°C PEB. [Figure 18] 1 shows two CD-SEM images of contact hole patterns prepared using photoresist samples containing A2 additive, each sample having undergone a double-bake-double-develop process. [Figure 19] Figure 1 shows a set of CD-SEM images of contact holes patterned in photoresist samples without additive or with additive A2, each sample undergoing either a single PEB and develop process or a double bake and double develop process. [Figure 20] 1 shows a set of CD-SEM images of contact holes patterned in photoresist samples with no additive or with a quencher additive, each sample subjected to either a 160°C PEB or a 180°C PEB. DETAILED DESCRIPTION OF THE INVENTION

[0015] The patterning of organometallic photoresists can be improved in some circumstances by the presence of additives, specifically photoacid generators and / or quenchers, in the photoresist film to reduce blurring of the pattern provided by radiation patterning. The additives can absorb photons and / or photoelectrons (secondary electrons), with or without the release of protons, in the so-called "dark areas" of the film, which are areas not nominally exposed to radiation. In particular, effective exposure in the dark areas can result in a reaction of the organometallic composition that leads to blurring. The improvements obtained from additives are particularly effective in the context of positive-tone patterning. In a typical lithography process, an aerial pattern of radiation is directed at the photoresist through the use of a pattern-providing mask, creating exposed and unexposed regions of the photoresist. However, photons generally follow a distribution that can be approximated by a Poisson distribution across the boundary between the exposed and unexposed regions of the pattern, and the number of photons penetrating the photoresist material in the nominally "unexposed" areas may be non-zero. The broadening of the radiation pattern at the boundary can exacerbate the range of secondary electrons, further blurring the image. Additives blended with radiation-sensitive organometallic compositions can capture, trap, or react with secondary electrons, effectively reducing the likelihood of electrons reacting with the organometallic composition. Additives can be selected to absorb primarily in the UV away from EUV, so these agents can be used for EUV patterning without significantly competing with the organometallic patterning composition for EUV light. Thus, the additive removes secondary electrons and reduces blurring while not reducing the efficiency of EUV patterning. In negative-tone embodiments, both the additive and its product after electron capture can be dissolved in an appropriate solvent, such as a developer and / or rinse composition. Quenching secondary electrons can be useful for reducing line roughness, reducing processing steps, sharpening feature edges, and / or increasing development effectiveness.

[0016] In EUV photolithography, shot noise and secondary electrons can cause significant edge blurring. EUV radiation for photolithography is generated by a plasma source with a three-dimensional spatial distribution that does not result in sharp edges in the pattern. "Masking" is typically performed using appropriately patterned mirrors, which can somewhat sharpen the light output. Although efforts to improve "masking" have been proposed, irradiation with EUV radiation has a radiation distribution at the edges. See, for example, U.S. Pat. No. 10,890,849 to Flagello et al., entitled "EUV Lithograph System for Dense Line Patterning," which is incorporated herein by reference. In addition to direct shot noise from the masking and irradiation process, secondary electrons and redirected light can result in effective irradiation of the material deeper in its "dark regions."

[0017] FIG. 1A is a schematic side view of an exposure process, in which a radiation source 102 is directed at a photomask 104. The photomask 104 forms an aerial image of photons that are delivered to the surface of a photoresist 106 on a substrate 108. As shown in FIGS. 1B-1C, the photon density distribution of the line-space pattern is not a square wave, but rather a distribution across exposed and unexposed regions. As an example, FIG. 1B shows a top-down schematic of photons delivered to the surface of the photoresist, in which the majority of photons, photons 156, fall or strike the surface of the photoresist in areas of pattern 154 that follow the pattern of the radiation, while some stray photons 158 (i.e., "shot noise" photons) fall in areas of pattern 152 that are intended to be shielded from the exposure radiation. 1C shows a side view of the distribution of photons 182 across a latent image 184 patterned in photoresist on a substrate 186, where the density of photons impinging on the resist generally follows the mask pattern, although some photon density may reside within the associated dark areas of the mask pattern. These photons can then be absorbed in such areas, causing photochemical reactions that may alter the solubility of species in the unexposed areas, resulting in exposure products similar in nature but different in magnitude from the photochemical reactions occurring in the exposed areas.

[0018] Organotin photoresists are generally known to function by the presence of radiation-sensitive tin-carbon bonds that can stabilize the photoresist film against violent condensation, resulting in a relatively low-density oxide material while imparting hydrophobic properties to the material through the presence of organic groups. Upon exposure to radiation and / or heating at elevated temperatures, the tin-carbon bonds are broken, leading to condensation / densification between adjacent tin centers, resulting in a more oxide-rich material. In this way, a suitable developer can extract the chemical contrast between exposed and unexposed regions of the photoresist film by selectively acting on the exposed or unexposed regions in a negative-tone or positive-tone process. For example, unexposed materials are generally soluble in organic-based solvents, while exposed materials are generally soluble in aqueous, acidic, or alkaline solvents. Other development processes, such as thermal or "dry" development processes, in which plasma or vapor flow may be used, can be used to remove the unexposed material.

[0019] Additives can be introduced into the photoresist composition during formulation of the photoresist precursor solution for introduction into the patterning material on the substrate. Organotin photoresists generally have a structure of the formula R n SnL 4-n where n=0.5-3 (or in further embodiments, n=0.75-2.0, where n is the average of the species present), and L is a ligand that forms a hydrolyzable bond with Sn, such as a dialkylamide (-NR'), an alkoxide (-OR'), an acetylide (-CCR'), a carboxylate (-COOR'), etc. Optionally, the organotin photoresist comprises, for example, a dodecamer "football" cluster [(RSn) 12 O 14 (OH)6] 2+and the hexameric "drum" cluster [RSnOOCR']6. These organotin compositions are generally dissolved in a suitable solvent to form an organotin photoresist solution. Additives generally effective as electron scavengers can be dissolved in these organotin photoresist solutions. In some embodiments, the additives can be added and / or dissolved in the organotin photoresist composition. In other embodiments, the additives can be added and dissolved in a solvent to form an additive solution, which can then be mixed with the organotin photoresist solution.

[0020] Organotin materials are known to exhibit dual-tone patterning behavior, allowing the desired patterning tone to be selected by selecting an appropriate developer. The chemistry of the patterning material results in increased metal oxide properties of the irradiated material, as opposed to the more organic nature of the unirradiated material. For example, organic developers generally result in negative-tone patterning of organotin materials, with unexposed material being removed from the substrate during development. Conversely, positive patterning can be achieved by development with an aqueous developer composition. Negative-tone patterning involves the removal of unirradiated material, and therefore, illumination of dark areas can hinder material removal. Positive-tone patterning involves the removal of irradiated material, and therefore, illumination of dark areas can remove some of the "unirradiated" material. Various effects, including edge blurring and illumination from secondary electrons, make it difficult to obtain sharp pattern edges.

[0021] The dual-tone nature of organotin patterning materials can be understood by the chemical properties of the material before and after exposure to an appropriate radiation source. As described herein and in applicant's earlier patents (Meyers et al.) cited below, photoresist films comprising organotin materials generally have a structure of the formula R n SnL 4-nThese films are prepared from the deposition of one or more organotin precursor compounds generally represented by the formula: where R is a hydrocarbyl ligand, L is a hydrolyzable ligand, and n generally represents the number of hydrocarbyl groups attached to the Sn atom and can be an integer between 0 and 4. Specific choices for the R group are provided below. In general, the overall stoichiometry usually has 0.5≦n<3, with desirable patterning results being obtained with n=1. These organotin precursor compounds can be hydrolyzed during the deposition process, hydrolyzing the hydrolyzable ligands while leaving the R-Sn bonds intact, driving condensation between Sn atoms and forming films containing an organometallic oxide hydroxide network represented by the formula RSnO(OH) (where n=1 for the above general formula).

[0022] Thus, the film contains hydrophobic RSn moieties that can be solubilized by organic developers. During exposure to ionizing radiation, the R-Sn bonds are cleaved, and the cleaved hydrophobic R groups are liberated from the film, leaving behind the more polar and hydrophilic irradiated material, which can then be removed by aqueous base developers. The removal of the R groups can be monitored spectroscopically. Therefore, the polarity difference between the irradiated and non-irradiated material allows for dual-tone patterning with appropriate developer selection. Around the pattern edges, there is an effective gradient of irradiation, which can be thought of as a gradient of dose relative to the dose received at the center of the irradiated area. In this way, the dose-dependent patterning behavior at the center of the pattern provides useful insight into patterning at the edges.

[0023] Referring to FIG. 2A, a plot of solubility versus pattern position (e.g., following an aerial image) illustrates that solubility is generally minimized in illuminated regions (e.g., lines) of pattern 202 and maximized in unilluminated regions (e.g., spaces) of the pattern. Some solubility threshold 204 is generally required to prevent removal of illuminated regions so that a negative-tone pattern can be achieved. However, as noted above, some shot noise photons may be absorbed in dark regions of the pattern, such as region 210, resulting in insoluble photoproducts that can be difficult to remove during the development process and thus remain part of the pattern as defects, as illustrated in FIG. 2B, particularly when the number of photochemical events in the dark regions of the pattern drives a decrease in solubility near or above the solubility threshold. Referring to FIG. 2C, a plot of solubility versus pattern position using a positive-tone developer illustrates that solubility is generally eliminated in unilluminated regions (e.g., lines) of pattern 220 and maximized in illuminated regions (e.g., spaces) of the pattern. To achieve a positive tone pattern, there is generally some solubility threshold 222 to avoid removal of unexposed areas. However, as noted above, some shot noise photons may be absorbed in unexposed areas of the pattern, such as area 224, resulting in soluble photoproducts that may be difficult to distinguish during the development process.

[0024] Absorbed EUV photons can break carbon-tin bonds, resulting in condensation of the material. As suggested above, side effects of EUV irradiation include the generation of high-energy primary photoelectrons, which in turn lead to the generation of lower-energy secondary electrons through scattering and / or ionization mechanisms, in a process commonly referred to as the secondary electron cascade. The secondary electrons can be thought of as radially dispersing around the initial absorption point. Interaction of the secondary electrons with the organotin patterning material can also cause carbon-tin bond scission, and depending on the electron mean free path, the secondary electrons create a blurring of the radiation pattern that can extend farther than the shot noise. This is shown schematically in Figures 2A-2C. To the extent that secondary electrons penetrate deeply (Figure 2A), condensation of unirradiated regions can result in more scum formation in negative patterning and generally a loss of depth of the remaining material in positive patterning. Even when the pattern dimensions are large enough that the secondary electrons do not penetrate the entire pattern (FIG. 2B—negative tone patterning and FIG. 2C—positive tone patterning), the line edges are blurred more than they would be with shot noise alone.

[0025] The additives described herein are photoacid generators and / or quenchers, generally organic, with suitable chemical compositions described further below. While the additives and any reaction products of the additives may be soluble in organic solvents, their presence in the patterning composition may prevent condensation of the irradiated material. Depending on the effective gradient of photon intensity at the pattern edge, the solubility also gradients, resulting in blurring of the edge. In a sense, changes in photon intensity correspond to different physical locations, effectively experiencing different sections of the dose plot, and corresponding blurring is observed.

[0026] In negative-tone patterning, irradiation causes the loss of organic ligands, rendering the irradiated material insoluble in organic solvents. During development, the unirradiated material is removed. Because the additive is an organic composition, its presence tends to facilitate the use of higher radiation doses to achieve the desired degree of condensation of the irradiated material. The inclusion of a PAG in an organotin resist has been described as useful for achieving reduced line edge roughness in negative-tone development. See U.S. Patent Application Publication No. 2021 / 0311387 to Woo et al., entitled "Semiconductor Photoresist Composition and Method of Forming Patterns Using the Composition," which is incorporated herein by reference. However, the presence of an additive presents a tradeoff in negative-tone patterning, and applicants have not found significant and consistent improvement by including a PAG or quencher additive for general negative-tone patterning. However, as described below, additives can effectively improve negative-tone patterning in a double-bake-double-develop process.

[0027] Positive-tone patterning can be achieved using organotin materials, but the window for suitable positive-tone patterning is generally limited by the degree of condensation (i.e., density) of the irradiated material. For illustrative purposes, a schematic contrast curve for positive-tone patterning in aqueous base is shown in Figure 3, plotting the thickness remaining after development against the dose delivered to the photoresist. Because the dose delivered to the wafer is greatest in the irradiated zone, the plot in Figure 3 can be assumed to be the reported dose for the patterning experiment, with the relevant measurements being taken at the center of the pattern. However, because the dose effectively drops off near the pattern boundaries, the dose plot also provides valuable information about the spatial effects of development for material removal based on a virtual image.

[0028] As shown in Figure 3, as the dose delivered to the photoresist increases and dealkylation occurs through cleavage of the R-Sn bond, the irradiated material becomes soluble in a developer, allowing it to be substantially removed from the substrate. Specifically, dealkylation increases the polarity of the irradiated material relative to the unirradiated material, allowing it to be dissolved in an aqueous base developer. However, as the dose continues to increase and the material becomes highly irradiated, density and condensation increase, and the developer can no longer selectively remove the material. Therefore, it is desirable to improve the solubility of the irradiated material in a positive-tone developer, thereby improving the positive-tone process window. A wider process window is generally desirable to provide relaxed dose and temperature requirements, allowing positive-tone patterning to be successfully achieved under a wider range of conditions.

[0029] As described herein, the presence of appropriate additives, including photoacid generators (PAGs) and / or quenchers, can improve the patterning of organotin materials. Improvements are particularly evident in the case of positive-tone patterning, and can be effectively exploited using the double-bake and double-develop process described below. Improvements in positive-tone processing can be achieved by adding additives that can improve the solubility of the irradiated material in aqueous developers (e.g., condensation inhibitors), reduce DO (the minimum dose required to remove the material), and / or improve the contrast of positive-tone development. These changes are evident in the contrast curve.

[0030] Referring to Figure 4, the goal is to steepen the tip of the dose curve so that once the irradiated resist begins to become soluble, further moderate increases in dose can result in complete removal of the irradiated material due to reduced condensation, providing more effective utilization of the solubility change in the developer. See Figure 5. With further increases in dose, the presence of the additive reduces condensation, allowing higher doses to be applied before condensation becomes excessive enough to inhibit development. See Figure 6. The overall effect is summarized in Figure 7. Zone 1 represents the low-dose region where the patterned material is lightly exposed, hydrophobic, and insoluble. Zone 2 represents the process window region where the material is moderately exposed, has a low-density SnOSn network, and is soluble. Zone 3 represents the development of highly exposed, dense SnOSn, and insoluble material.

[0031] In some embodiments, a suitable additive can include a photoacid generator (PAG). Without wishing to be limited by theory, evidence suggests that the presence of a PAG within the organotin matrix can improve the susceptibility of organotin species to dealkylation after EUV exposure and during the post-exposure bake (PEB) step by promoting radiation-induced thermal decomposition. During exposure to radiation, Sn-C bonds are cleaved within the irradiated material. It has been found that the thermal stability of the hydrocarbyl compounds remaining in the material after irradiation is significantly reduced, and that this thermal stability decreases with decreasing Sn-C concentration. In other words, as the concentration of Sn-C bonds in the irradiated material decreases, the thermal stability of the remaining Sn-C bonds in the irradiated material also decreases. Thus, as shown in the examples below, after an initial amount of Sn-C bonds are cleaved upon exposure to radiation, subsequent baking can promote further cleavage of Sn-C bonds via thermal decomposition in a phenomenon known as radiation-induced thermal decomposition. The radiation-induced thermal decomposition phenomenon can enable improved processing methods for the materials described herein, such as processes involving multiple bakes and multiple develops.

[0032] As shown in the examples below, the presence of a PAG in a photoresist can improve the efficiency of the radiation-induced thermal decomposition process by improving the amount of thermal decomposition (i.e., Sn-C bond cleavage due to heating) during the bake process after exposure to radiation. Without wishing to be limited by theory, it is believed that photoacid generation during radiation exposure can facilitate stabilization of fragments resulting from Sn-C bond cleavage during irradiation and / or the subsequent bake process. Thus, organotin compositions including a PAG can provide improved solubility of the exposure products in positive-tone developers.

[0033] In some embodiments, suitable additives can include quenchers capable of neutralizing acidic protons. As described further below, both PAGs and quenchers can act as electron scavengers. Thus, the quenchers and PAGs in the photoresist film can absorb photons and / or secondary electrons to limit the spatial diffusion of C-Sn bond cleavage. Because the quencher neutralizes acidic protons, the quencher produces photoproducts that do not significantly alter the radiolysis of the organotin material in the irradiated areas of the photoresist.

[0034] In irradiated areas of the photoresist, many photons are absorbed, forming a cascade of secondary electrons, which can cause tin-carbon bond breakage within the material. However, in non-irradiated areas, fewer photons impinge on the material, and the presence of an electron scavenger significantly "quenches" the secondary electrons that are generated, thereby reducing the number of tin-carbon bond scission events that would otherwise result in defect-causing irradiation products in the dark areas. The use of an organotin photoresist composition containing an electron scavenger can change the solubility profile of the photoresist so that the dark areas of the nominally unirradiated pattern exhibit increased solubility. In other words, an organotin photoresist composition containing an electron scavenger can reduce the number of photochemical events that lead to insoluble species caused by the absorption of shot noise photons.

[0035] Furthermore, the additive compositions described herein can be useful for improving the positive-tone process window of organotin photoresists. After radiation exposure and subsequent baking, the radiation-sensitive hydrocarbyl ligands are cleaved and removed from the film, resulting in irradiated areas containing a condensed oxide-hydroxide network. As the radiation dose and / or PEB temperature increase, more hydrocarbyl ligands are removed from the film, increasing the degree of condensation and / or density of the oxide-hydroxide network. In conventional patterned-tone processing of organotin materials, at high doses and / or PEB temperatures, the resulting oxide-hydroxide network can condense / densify to the point where it becomes insoluble in aqueous base developers. The use of the additive compositions described herein can inhibit the condensation process that occurs at higher doses and improve the solubility of irradiated areas in aqueous base developers.

[0036] Positive-tone patterning of organotin materials is made possible by radiation-induced polarity changes in the photoresist film. The inclusion of organic hydrophobic additives in organotin photoresist compositions can be useful for improving the solubility of radiation-exposed products without significantly increasing the solubility of unexposed and / or lightly exposed materials. Conversely, the presence of such additives in organotin photoresist films can prevent condensation and oxide-hydroxide network formation after irradiation and / or baking, thus improving the solubility of the photoresist at higher doses. In this way, the process window for positive-tone patterning (i.e., the dose at which the photoresist dissolves) can be improved.

[0037] The effect of the additive can be utilized in the context of sequential development, where a first PEB is performed with development, followed by a second PEB at a higher temperature, followed by a second development step. This double bake-double develop (DBDD) procedure can be effectively applied to either positive-tone or negative-tone processes. It is believed that the second bake step after the first development step results in further release of organic species from the irradiated material, which can then further condense the material.

[0038] For positive-tone development, the additive-induced reduction in condensation provides a broader, higher-dose edge of the process window, which can be particularly advantageous for DBDD processes. For example, if a somewhat lower temperature is used for the first PEB, the irradiated material will not condense as much and can be substantially removed by aqueous base in the first development. If the second PEB is performed at a higher temperature, the high-dose exposed material will already be substantially removed, so further condensation provided by the second PEB will not be detrimental to the process window. However, the second PEB can promote dealkylation and condensation of material near DO, increasing the solubility of this material in aqueous base developer, thus broadening the process window and improving positive-tone contrast. Thus, overall, the DBDD process enables a broadening of the process window for positive development by lowering the dose required to dissolve the material in aqueous base developer (e.g., as shown in Figure 5 ), while also increasing the dose required for solubility loss behavior observed at sufficiently high doses (e.g., as shown in Figure 6 ).

[0039] The DBDD process can exhibit improved positive-tone patterning compared to the single PEB and single develop process and compared to the double PEB and single develop process, leveraging the effects of both processes as shown in FIG. 8 . The single PEB and develop (PEB1 / Dev1) process (252) generally targets the dose of the high-dose transition in the aqueous base developer, which is generally desired to be as high as possible for optimal positive-tone processing. A lower PEB temperature can increase the dose in this high-dose transition region. However, lower PEB temperatures also result in less radiation-induced thermal decomposition of the partially irradiated material, which generally leads to higher positive-tone D values. A PEB process sequence 254 (PEB1 / PEB2 / Dev1) of a first low-temperature PEB and a second high-temperature PEB with a single develop can be used to drive more radiation-induced thermal decomposition in the partially irradiated material and increase its solubility in the aqueous base developer. However, widespread condensation and densification in the fully irradiated areas also occurs, resulting in greater insolubility in aqueous base developers and an overall narrower positive tone process window. By implementing a DBDD process, the benefits of both single development processes can be realized, where a first, low-temperature PEB and development process can remove a significant amount of the irradiated material, and a second, high-temperature PEB and development process can promote increased solubility of the partially irradiated material.

[0040] Regarding the impact of the behavior seen in the contrast curve on the actual effect of patterning properties, if patterning is performed at a dose corresponding to the solubility window in the developer, the low-dose side of the process curve corresponds to a physical location near the pattern edge, so a wider process window may correspond to less residue at the pattern edge for a cleaner pattern. Suitable developers for positive tone development are aqueous weak acids or bases, such as tetramethylammonium hydroxide (TMAH), and the first and second developers can be the same or different.

[0041] For negative-tone development, the irradiation only serves to prevent material removal during development, so there is no low-dose end to the process curve. The material to be removed is either not irradiated or is irradiated at a dose insufficient to render it insoluble. The second bake step again induces further condensation of the irradiated material. For negative-tone development, the effect of the second bake-develop step is not related to the process window of the process curve; edge effects are related to the shape of the process curve as the dose increases. By limiting condensation, the process curve slopes more gently at lower doses. Further condensation occurs during the second bake. Second developers for negative-tone development can generally be more effective at removing hydrophilic materials. Therefore, the second developer can be a blend of TMAH, an organic developer, and an acid (e.g., heptanone and acetic acid). The second development step must be effective to modify the process curve so that it rises more steeply. This is shown in Figure 9. A sharper process curve can result in less residue along the pattern edges when performing negative tone patterning with a DBDD process as described herein.

[0042] For high-volume semiconductor manufacturing, it is generally desirable for photoresists to have high sensitivity to radiation so that a lower energy dose is required to pattern features of a desired size. The ongoing demand for improved efficiency and throughput generally necessitates improvements in the semiconductor lithography ecosystem, particularly the need for improved photoresist sensitivity to exposure radiation. Increasing photoresist sensitivity reduces the number of photochemical reactions required to cause a solubility change in the photoresist. Because the energy density of EUV photons is significantly higher than that of ultraviolet or visible photons, the number of photons required to deliver a given dose is significantly lower than that of longer wavelength photons. In other words, compared to longer wavelength photons, such as ultraviolet or visible photons, generating a latent image pattern in a photoresist does not require as many EUV photons. Therefore, as the dose requirements for patterning photoresists decrease, it is desirable to mitigate the photochemical effects of photons delivered to unexposed areas of the pattern.

[0043] Organotin materials are particularly useful as organometallic photoresists for semiconductor lithography. Organotin photoresists are extensively described in U.S. Pat. No. 9,310,684 B2 to Meyers et al., entitled "Organometallic Solution Based High Resolution Patterning Compositions," U.S. Pat. No. 10,642,153 B2 to Meyers et al., entitled "Organometallic Solution Based High Resolution Patterning Compositions and Corresponding Methods," and U.S. Pat. No. 10,228,618 B2 (the '618 patent) entitled "Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning," all of which are incorporated herein by reference. Generally, these organotin photoresist materials are deposited as coatings in which Sn atoms are linked into an oxo-hydroxo network via Sn-OH and Sn-O-Sn bonds, along with intact Sn-C bonds. The intact Sn-C bonds prevent the expansion of high-density networks, thus maintaining the film's adequate solubility in the developer. Exposure of the organotin coating to a suitable radiation source, such as extreme ultraviolet (EUV), ultraviolet (UV), or electron beam, breaks the Sn-C bonds, allowing further densification of the exposed areas, thereby increasing the solubility contrast between the exposed and unexposed areas. In this way, patterning of the coating can be achieved after development. Organotin photoresists are currently commercially available from the applicant, Inpria Corporation.

[0044] Organotin resists can be useful for either negative-tone or positive-tone patterning. Patterns formed using organotin resists are not particularly limited and can generally include complex layouts based on various mask patterns for device fabrication. For testing photoresist performance, masks containing line / space and / or contact hole patterns can be particularly useful. In some embodiments, the patterns can be based on regularly spaced lines and patterned gaps between them (i.e., line / space patterns) or holes on a lattice (i.e., contact hole patterns). Forming holes on a lattice is particularly suitable for positive-tone patterning. In the case of negative patterning of holes, the area around the holes can be irradiated, but in this case, the holes are subject to secondary electrons and shot noise from all directions, which can easily leave a large amount of residue in the holes. As demonstrated below, positive-tone patterning of holes can be effectively performed using the methods described herein.

[0045] The additive can be dissolved in the solvent used to deliver the organotin patterning precursor to the substrate. As mentioned below, the solvent can be selected to achieve appropriate solubility of all relevant species. Processing can continue with deposition and irradiation. After irradiation, development can be adjusted as described above to take advantage of the presence of the additive. Overall, processing with the additive can be effectively used for patterning that benefits from positive tone patterning, such as hole formation, or when a double development approach is desired to improve pattern quality.

[0046] Precursor solutions, organotin precursor compositions and additives The additive is mixed with the precursor in a solvent to form a precursor solution of the organotin patterning composition for delivery to the substrate. The solvent for the organotin precursor is generally suitable for dissolving the additive, or can be selected depending on the situation. The additive is generally present in a molar ratio of less than 2 to tin atoms. As mentioned above, the additive can be a PAG, a quencher, or a combination thereof.

[0047] The precursor solution generally comprises an organometallic precursor composition, an additive, and an organic solvent. Resist precursor compositions can be conveniently specified based on the molar concentration of tin ions. In general, resist precursor solutions generally comprise about 0.0025M to about 1M tin cations, in some embodiments about 0.004M to about 0.9M, in further embodiments about 0.005M to about 0.75M, and in some embodiments about 0.01M to about 1M, and in additional embodiments about 0.01M to about 0.5M tin cations. With respect to additives, these can be specified as a molar ratio or molar concentration relative to tin. The additive may be present in the solution in a molar ratio relative to tin of 0.002 to 0.5, in further embodiments about 0.0035 to about 0.45, in additional embodiments about 0.005 to about 0.4, and in some embodiments about 0.0075 to about 0.3 (moles additive / moles tin). Similarly, the precursor solution can include an additive at a concentration from about 0.000025 M to about 0.4 M, in further embodiments from about 0.00005 M to about 0.35 M, and in additional embodiments from about 0.0001 M to about 0.2 M. A person of ordinary skill in the art will recognize that additional concentration ranges and values ​​within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0048] Suitable organic solvents include, for example, alcohols or blends thereof. Generally, the solvent is at least 50 weight percent alcohol, with any remaining organic solvents, such as alkanes (e.g., pentane or hexane), aromatic hydrocarbons (e.g., toluene), ethers (e.g., diethyl ether, C2H5OC2H5), or mixtures thereof, being soluble in the alcohol. As shown in the examples below, the solvent can be adjusted to ensure adequate solubility of the organotin precursor and any additives. In some embodiments, the solvent is at least 90 weight percent alcohol, and the solvent can effectively be alcohol containing trace impurities of other compounds. Suitable alcohols are typically monomeric alcohols with melting points of about 10°C or less, such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, branched versions thereof, and mixtures thereof. It has been found that controlling the water level can result in consistent and stable precursor solutions. In particular, the water level can be adjusted, typically by adding small amounts of water to the solvent, to achieve a target water level of about 10,000 ppm by weight or less, and in additional embodiments, about 300 ppm to about 2500 ppm by weight. 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 use of water content adjustment is further discussed in U.S. Pat. No. 11,300,876 to Jiang et al., entitled "Stable Solutions of Monoalkyl Tin Alkoxides and Their Hydrolysis and Condensation Products" (the '876 patent), which is incorporated herein by reference.

[0049] The organotin compositions can be alkyltin compositions, including a group of compositions (RSnL3) that can be hydrolyzed under appropriate conditions with water or other suitable reagents to form monohydrocarbyltin oxo-hydroxo patterning compositions, which, when fully hydrolyzed, have the formula RSnO (1.5-(x / 2)) (OH)x It can be represented by (where 0 < x ≤ 3). It can be convenient to perform hydrolysis to form an oxo-hydroxy composition in situ, such as during deposition and / or after initial coating formation. In particular, triamides and trialkoxides can be used under hydrolysis conditions to form radiation-sensitive coatings for patterning, and current commercial products are based on trihydrocarbyloxides such as trialkoxides. Various precursor compounds having hydrolyzable ligands generally direct the R ligand towards tin through the process and are synthesized from this perspective. Hydrolyzable ligands include, for example, alkoxides (hydrocarbyloxides), acetylides, carboxylates, or amide moieties. These compositions can be synthesized using a wide range of R ligands, where R is a hydrocarbyl ligand having 1 to 31 carbon atoms, with optional heteroatoms and / or optional unsaturated or aromatic functionality while maintaining a carbon-tin bond. Various synthetic approaches are available based on methods known in the art or developed by the applicant, and a particularly versatile approach that can provide good yields for a wide range of ligands can be found in U.S. Patent Application Publication No. 2022 / 0064192 to Edson et al. entitled "Methods to Produce Organotin Compositions with Convenient Ligand Providing Reactants", which is incorporated herein by reference.

[0050] For an organotin RSnL3 composition (or more generally, R n SnL 4-n , where 0.5 < n < 3), R can form a carbon-tin bond and can contain heteroatoms that are not carbon or hydrogen. As described above, for convenience and to maintain technical consistency, R may also be interchangeably referred to as an alkyl ligand, an organic ligand, or a hydrocarbyl ligand. In some embodiments, branched alkyl ligands are such that the compound is generally R 1 R 2 R 3 CSnO<00000​x (In the formula, R 1 , R 2 and R 3 It may be desirable for some patterning compositions to have the alkyl ligand R represented as: 1 R 2 R 3 It is equally applicable to other embodiments having CSn(L)3, where L corresponds to a hydrolyzable ligand such as an alkoxide (hydrocarbyloxide), acetylide, carboxylate, or amide moiety. In some embodiments, R 1 and R 2 can form a cyclic alkyl moiety, and R 3 can be linked to other groups on 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 1 and 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 3is -C(CH3)3), cyclohexyl, cyclopentyl, cyclobutyl, and cyclopropyl. Examples of suitable cyclic groups include, for example, 1-adamantyl (bonded to the metal at a tertiary carbon, -C(CH2)3(CH)3(CH2)3 or tricyclo(3.3.1.13,7)decane) and 2-adamantyl (bonded to the metal at a secondary carbon, -CH(CH)2(CH2)4(CH)2(CH2) or tricyclo(3.3.1.13,7)decane). In other embodiments, the hydrocarbyl group can comprise an aryl or alkenyl group, such as benzyl or allyl, or an alkynyl group. In other embodiments, the hydrocarbyl ligand R can comprise any group consisting exclusively of C and H and containing 1 to 31 carbon atoms. In summary, some examples of suitable alkyl groups attached to tin include, for example, linear or branched alkyl (i-Pr((CH3)2CH-), t-Bu((CH3)3C-), Me(CH3-), n-Bu(CH3CH2CH2CH2-)), cycloalkyl (cyclopropyl, cyclobutyl, cyclopentyl), olefin (alkenyl, aryl, allyl), or alkynyl groups, or combinations thereof. In further embodiments, suitable R groups can include hydrocarbyl groups substituted with cyano, thio, silyl (and germanium analogs), ether, keto, ester, or halogenated groups, or combinations thereof, such as heteroatom functional groups containing one or more fluorine atoms and / or one or more iodine atoms. As is conventional in the art, hydrocarbyl groups are sometimes referred to as alkyl groups, even though they may have unsaturated bonds, aryl groups, heteroatoms, etc.

[0051] As mentioned above, suitable additives can be photoacid generators (PAGs), quenchers, or a combination thereof. These compositions are generally ionic or zwitterionic. In some embodiments, suitable PAGs and quenchers can be based on a common cation, with the compositions differing by the nature of the anion. PAGs generally have anions that are the conjugate base of a strong acid so as not to be significantly alkaline, while quenchers have anions that are alkaline so as to neutralize or buffer released or otherwise present protons. As their names suggest, quenchers can remove or neutralize acid and limit its spatial extent. Generally, either compound absorbs secondary electrons or UV light to generate acid (PAGs) or not (quenchers). Acid generation has been shown to facilitate the removal of cleaved R groups from the patterning composition, and in either case, removing secondary electrons and limiting their extent can be beneficial. The use of PAGs to absorb secondary electrons is described in U.S. Patent Application Publication No. 2018 / 0173096 to Zi et al., entitled "Extreme Ultraviolet Photolithography Method With Developer Composition," which is incorporated herein by reference.

[0052] In some embodiments, the electron scavenger of the additive can be a compound capable of absorbing photons or electrons (e.g., secondary electrons and / or photoelectrons) to generate a soluble reaction product. In some embodiments, the electron scavenger can be a compound capable of absorbing photons or electrons to generate a product that can react with the organotin matrix to generate a soluble reaction product. The additive in the photoresist film can absorb photons and / or secondary electrons to generate a photoproduct, which does not significantly alter the radiolysis of the organotin material in the irradiated areas of the photoresist during EUV patterning due to the generally weak absorption of EUV by the additive. In the irradiated areas of the photoresist, many photons are absorbed to form a cascade of secondary electrons, which can cause tin-carbon bond breakage within the material. However, in the non-irradiated areas, fewer photons strike the material, and the presence of the additive, which can function as an electron scavenger, significantly "quenches" the generated secondary electrons, thereby reducing the number of tin-carbon bond scission events that would otherwise result in insoluble products (i.e., defects). As mentioned above, the absorption of electrons by the additive may or may not result in the release of acid. As mentioned above, the use of an organotin photoresist composition containing an additive can modify the solubility profile of the photoresist so that the dark areas of the pattern that are not nominally irradiated exhibit increased solubility in negative tone developers while maintaining low solubility in positive tone developers. In other words, an organotin photoresist composition containing an additive as an electron scavenger can reduce the number of photochemical events that lead to insoluble species caused by the absorption of shot noise photons or secondary electrons.

[0053] Without wishing to be bound by theory, it is believed that the additive acts similarly to a competitive inhibitor or quencher with respect to the photochemical reactions of the organotin matrix, particularly those occurring in non-irradiated areas due to stray radiation. It is generally believed that radiation decomposition occurs when a photon is absorbed by the photoresist film composition, producing ionized products and secondary electrons (i.e., photoelectrons) within the photoresist film. These secondary electrons can then travel through the film and drive further ionization events. These secondary electrons can drive photochemical reactions, such as dealkylation of organotin species (e.g., R-Sn bonds) within the organotin photoresist film. While dealkylation is generally desirable in nominally irradiated areas of the photoresist, it is generally undesirable for dealkylation to occur in non-irradiated areas of the photoresist. Thus, the additive compositions described herein can be used to mitigate undesired dealkylation events in non-irradiated areas of the photoresist. In this manner, the additive compositions can improve the performance of organotin photoresists.

[0054] As mentioned above, the additive can be a photoacid generator (PAG), a quencher, or a mixture thereof. PAGs, which generate acid in response to light and / or heat absorption, are known in the photolithography field. While PAGs generally can absorb at UV and EUV wavelengths, the presence of the PAG in a Sn-based matrix, which already has high EUV absorbance, means that the EUV light available to the organotin patterning composition is not significantly attenuated by the presence of the PAG. PAGs can also generate acidic protons in response to secondary electrons generated from EUV absorption. Evidence herein suggests that PAGs facilitate the removal of organic species from the irradiated patterning composition, presumably related to the release of cleaved R groups from their bonds to tin.

[0055] PAGs generally have an anion and a cation, but may also be zwitterionic. PAGs known in the art are generally onium compounds with a cation formed from a core atom from Groups 15 to 17, such as iodonium, sulfonium, ammonium, or phosphonium. Particularly effective PAGs have aromatic substituents and their derivatives.

[0056] The anion counterion of PAG is generally a conjugate base of a strong acid, so the anion does not neutralize the acid released from the cation. However, the anion must be appropriately selected to maintain solubility in organic solvents. Therefore, various anions are common in the art based on appropriate solubility and availability. Specifically, aromatic sulfonates are effective anions. Suitable anions generally include, for example, naphthalene-1-sulfonate, naphthalene-2-sulfonate, 2-t-butyl-naphthalene-2-sulfonate, etc.; anthracene derivatives, for example, anthracene-1-sulfonate, anthracene-2-sulfonate, 9-nitroanthracene-1-sulfonate, 5,6-dichloroanthracene-3-sulfonate, 9,10-dichloroanthracene-2-sulfonate, 9,10-dimethoxyanthracene-2-sulfonate, 9,10- diethoxyanthracene-2-sulfonate, benz(a)anthracene-4-sulfonate, etc.; other types of anions having polycyclic structures, such as phenanthrene-2-sulfonate, pyrene-sulfonate, triphenylene-2-sulfonate, chrysene-2-sulfonate, anthraquinone-sulfonate, etc.; trifluoromethanesulfonate; hexafluoroantimonate; tetrafluoroborate; hexafluorophosphate; benzenesulfonate, etc.

[0057] Desirable quenchers can have the same cation as PAG to provide secondary electron reaction, but have an anion that is alkaline to neutralize or buffer the acidic protons. The anion can be a hydroxide, which neutralizes the acidic protons, or a weak base, such as a carbonate or sulfate, that can still be effective in binding the acidic hydrogen.

[0058] Onium salt-based quenchers are described in U.S. Patent Application Publication No. 2023 / 0161254 to Fukushima et al., entitled "Chemically Amplified Resist Composition and Patterning Process," (hereinafter the '254 Application), which is incorporated herein by reference. The '254 Application teaches a range of onium cations and lists certain aromatic species that are desirable from a solubility standpoint and from a secondary electron quenching standpoint, although aromatic compounds with smaller steric bulk may be desirable to avoid excessive inhibition of condensation of the irradiated material. The '254 Application uses RCO2 as the anion. - are mentioned, where R is a hydrocarbyl group, possibly heteroatom-substituted. R in these anions can be H or a hydrocarbyl group having 1 to 40 carbon atoms and optional heteroatoms. The R group can be selected for desired solubility characteristics and process convenience and can include aromatic groups. PAG anions can include sulfonate or phosphonate groups with organic functional groups that can include 1 to 40 carbon atoms, along with optional heteroatoms. In the case of quenchers and / or PAG anions, it may be desirable to have aromatic groups for solubility.

[0059] As mentioned above, onium ions are similar to ammonium and can have core atoms from various groups in the periodic table. Onium ions of particular interest have core atoms from Group 15 (N, P, As, Sb, or Bi), Group 16 (O, S, Se, Te, or Po), or Group 17 (I, F, Cl, or Br), although ions are known for boron, Group 14 atoms, and the noble gases. Onium ions are usually AR n + where "A" represents the core atom of the ion, R represents a ligand of A, and n is the number of ligands. R is generally a hydrocarbyl group having 1 to 20 carbon atoms and optional heteroatoms. R may desirably include an aromatic group such as a benzyl group, and fluorine or other halogen substitution may be desirable, such as a fluorobenzyl group. Sulfonium ions and iodonium ions are exemplified herein. Some specific species are shown below.

[0060] Some suitable examples of quenchers include organic iodonium hydroxides such as diphenyliodonium hydroxide and bis(3-tert-butylphenyl)iodonium hydroxide, and organic sulfonium hydroxide compounds such as triphenylsulfonium hydroxide, tris(4-fluorophenyl)sulfonium hydroxide, and diphenyl(4-cyclohexylphenyl)sulfonium hydroxide. [ka]

[0061] When an electron scavenger is included in the organotin composition, the agent may be reacted with the organotin compound according to the following reaction scheme: [ka] As shown in Figure 1, electron capture can mitigate undesired Sn-C bond scission in the unirradiated areas of the photoresist film, resulting in soluble products.

[0062] In some embodiments, the electron scavenger can first be dissolved in a solvent different from that containing the organotin photoresist solution and then combined with the organotin photoresist solution to form the additive-modified organotin photoresist solution. Generally, it is desirable for the electron scavenger additive to be dissolved in a solvent that is conducive to processing of the resulting additive-modified organotin photoresist solution.

[0063] Photoelectron absorbers for organic photoresists, including chemically amplified photoresists, are described in U.S. Patent Application Publication No. 2009 / 0317742 to Toriumi et al., which is incorporated herein by reference. The photoelectron absorbers described by Toriumi et al. are described as being suitable for photosensitive resin compounds composed primarily of hydrogen, carbon, and oxygen. Toriumi et al. does not consider organotin photoresist compositions or the problem of off-target tin-carbon bond cleavage. In general, it is desirable to use metal-free compounds herein to avoid metal contamination. Additionally, hydroxide anions are desirable to avoid the formation of photoacid generators.

[0064] After forming the organotin photoresist solution containing the electron scavenger, the solution can be further processed, such as by filtration, to properly prepare the solution for use. Filtration can be effective in removing inhomogeneities, such as undesired particles, from the organotin resist solution. Such a method is described by Clark et al. in U.S. Patent Application Publication No. 2020 / 0239498, entitled "Monoalkyl Tin Trialkoxides And / Or Monoalkyl Tin Triamides With Particulate Contamination And Corresponding Methods," which is incorporated herein by reference.

[0065] Patterning of the composition As described above, a photoresist precursor solution containing an organotin composition and an additive (additive-augmented photoresist precursor solution) can be used to form a radiation-patternable organotin oxohydroxo material incorporating an additive, and such coatings can be formed using any suitable method known in the art. Spin coating can be particularly desirable for forming coatings using an additive-augmented photoresist precursor solution. In a typical spin coating process, a volume of the additive-augmented photoresist solution is introduced to the surface of a substrate, and the substrate is spun at a high speed to promote a rapid evaporation and hydrolysis process, enabling the formation of a radiation-patternable coating. In some embodiments, the substrate can be spun at a speed (i.e., spin speed) of about 500 rpm to about 10,000 rpm, in further embodiments about 1000 rpm to about 7500 rpm, and in additional embodiments about 2000 rpm to about 6000 rpm. The spin speed can be adjusted to obtain a desired coating thickness. Spin coating can be carried out for about 5 seconds to about 5 minutes, and in further embodiments about 15 seconds to about 2 minutes. An initial slow spin speed, e.g., 50 rpm to 250 rpm, can be used to achieve initial bulk spreading of the composition across the substrate. A backside rinse, edge bead removal step, or the like, can be performed with water or other suitable solvent to remove any edge bead. A person of ordinary skill in the art will recognize that additional ranges of spin-coating parameters within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0066] A substrate generally presents a surface onto which a coating material may be deposited, and the substrate may include multiple layers, with the surface being associated with a top layer. The substrate surface may be treated to prepare the surface for adhesion of the coating material. Prior to surface preparation, the surface may be cleaned and / or smoothed, as needed. Suitable substrate surfaces may comprise any suitable material. Substrates of interest include, for example, silicon wafers, silica substrates, other inorganic materials, polymeric substrates such as organic polymers, composites thereof, and combinations thereof across the surface of the substrate and / or within layers. In some embodiments, the substrate may include a patterned structure, such as those described by Stowers et al. in U.S. Pat. No. 10,649,328, entitled "Pre-Patterned Lithography Templates, Process Based on Radiation Patterning Using The Templates And Processes To Form The Templates," incorporated herein by reference.

[0067] The thickness of the coating can generally be a function of the concentration and viscosity of the precursor solution and the spin-coating rotation speed. For other coating processes, the thickness can also generally be adjusted by selecting coating parameters. In some embodiments, it may be desirable to use a thin coating to facilitate the formation of small, high-resolution features in a subsequent patterning process. For example, the coating material after drying can have an average thickness of greater than about 250 nanometers (nm), from about 1 nm to about 50 nm in additional embodiments, from about 2 nm to about 40 nm in other embodiments, and from about 3 nm to about 25 nm in further embodiments. Those skilled in the art will recognize that additional ranges of thickness within the explicit ranges above are contemplated and are within the scope of the present disclosure. Thickness can be assessed using non-contact methods such as x-ray reflectivity and / or ellipsometry based on the optical properties of the film. Generally, the coating is relatively uniform to facilitate processing. In some embodiments, for example, for highly uniform coatings on moderately sized substrates, assessment of the coating uniformity or flatness can be assessed with, for example, a one-centimeter edge exclusion. That is, the coating uniformity is not evaluated within 1 centimeter of the edge of the coating, although other suitable edge exclusions may be selected.

[0068] While heating may not be required for successful application of the deposition process, it may be desirable to heat the coated substrate to densify the coating material, accelerate processing, increase process reproducibility, and / or promote evaporation of hydrolysis by-products such as alcohols and / or amines. In embodiments in which heating of the coated substrate is performed before irradiation, the coated substrate may 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 may generally be performed for at least about 0.1 minutes, in further embodiments from about 0.5 minutes to about 30 minutes, and in additional embodiments, from about 0.75 minutes to about 10 minutes. 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.

[0069] Generally, photoresist coatings can be patterned using radiation. Suitable radiation sources include extreme ultraviolet (EUV), ultraviolet (UV), or electron beam (EB) radiation. In semiconductor device manufacturing, EUV radiation can be desirable due to its higher resolution compared to UV radiation and higher throughput compared to electron beam (EB)-based processes. The effectiveness of additives can be particularly pronounced when using EUV radiation, because additives generally do not strongly absorb EUV radiation and therefore do not reduce the effective light intensity of the organotin material. Typically, radiation is directed at the substrate material through a mask, or a radiation beam can be controllably scanned across the substrate to form a latent image in the resist coating. As mentioned above, in the case of EUV "masking," patterns are formed using mirrors to reflect and direct light from a plasma source.

[0070] According to International Standard ISO 21348 (2007), incorporated herein by reference, ultraviolet light spans the wavelength range between 100 nm and less than 400 nm. Krypton fluoride lasers can be used as a source of ultraviolet light at 248 nm. The ultraviolet range can be subdivided in several ways under accepted standards, including 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 source of FUV radiation. EUV light has been used for lithography at 13.5 nm, and this light is generated from Xe or Sn plasma sources excited using high-energy lasers or discharge pulses. Commercial sources of EUV photons include scanners manufactured by ASML Holding NVNetherlands. Soft x-rays can be defined as from 0.1 nm to less than 10 nm.

[0071] The amount of electromagnetic radiation can be characterized by a fluence or a dose, which is obtained by integrating the radiative flux with respect to exposure time. In embodiments where EUV radiation is used, a suitable radiation dose is about 1 mJ / cm. 2 ~Approx. 150mJ / cm 2 and in a further embodiment about 2 mJ / cm 2 ~about 100mJ / cm 2 and in a further embodiment about 3 mJ / cm 2 ~about 50mJ / 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.

[0072] After exposure to radiation and formation of the latent image, a subsequent post-exposure bake (PEB) is typically performed. In some embodiments, the PEB can be performed at a temperature of from about 45°C to about 250°C, in additional embodiments from about 50°C to about 190°C, and in further embodiments from about 90°C to about 185°C. The post-exposure bake typically can be performed for at least about 0.1 minutes, in further embodiments from about 0.5 minutes to about 30 minutes, and in additional embodiments from about 0.75 minutes to about 10 minutes. 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 scope of the present disclosure. The PEB can be designed to further strengthen the exposed areas without decomposing the unexposed areas into metal oxides.

[0073] Applicants have found that PEB can significantly contribute to radiation-induced pyrolysis. In other words, irradiated structures can initially undergo radiolysis, whereby irradiation induces cleavage of hydrocarbyl ligands and removal of product species formed from the cleaved ligands. However, PEB has also been found to result in the loss of additional organic moieties from the irradiated material, which can be referred to as radiation-induced pyrolysis, since neither treatment individually results in the same degree of organic species loss from the material. The loss of organics from the material can be measured using infrared spectroscopy tuned to organic frequencies, as further described in the Examples. PAG has been found to improve the effectiveness of radiation-induced pyrolysis. Furthermore, increasing the PEB temperature above 160°C has also been found to improve radiation-induced pyrolysis. The PEB temperature can also be controlled to achieve the desired results from a bake-develop-bake-develop (double bake-double develop or DBDD) protocol, as further described below.

[0074] After PEB, image development involves contacting the patterned coating material containing the latent image with a developer composition to either remove the non-irradiated coating material to form a negative image or remove the irradiated coating to form a positive image. The irradiated areas of the organotin oxide hydroxide coating are generally hydrophilic and therefore soluble in aqueous bases and insoluble in organic solvents. Conversely, the non-irradiated areas are generally hydrophobic and therefore soluble in organic solvents and insoluble in aqueous bases. For negative-tone imaging, the developer can be an organic solvent, such as the solvent used to form the precursor solution.

[0075] Specifically, for positive-tone imaging, a suitable developer can generally be an aqueous base. In some embodiments, using an aqueous base can result in a clearer image. To reduce contamination from the developer, it may be desirable to use a developer that does not contain metal atoms. Therefore, quaternary ammonium hydroxide compositions, such as tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or combinations thereof, are desirable positive-tone developers. In general, quaternary ammonium hydroxides of particular interest can be represented by the formula R4NOH, where R = methyl, ethyl, propyl, butyl, or combinations thereof. The coating materials described herein can generally be developed using the same developers currently commonly used for polymer resists, specifically tetramethylammonium hydroxide (TMAH). Commercially available TMAH is available at 2.38 weight percent. Additionally, mixed quaternary tetraalkylammonium hydroxides can be used. Generally, the developer may comprise from about 0.5 to about 30 weight percent, 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 a tetraalkylammonium 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 scope of the present disclosure. For positive tone developers, it may be desirable to dissolve densified material with a relatively high radiation dose, provided that unirradiated material is not significantly removed. This further widens the process window.

[0076] For negative-tone imaging, the developer can be an organic solvent, such as the solvent used to form the precursor solution. Generally, the choice of developer can be influenced by the solubility parameters of both irradiated and non-irradiated coating materials, as well as the developer's volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials. In particular, suitable developers include, for example, aromatic compounds (e.g., benzene, xylene, toluene), esters (e.g., propylene glycol monomethyl ester acetate (PGMEA), 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. Improved developer compositions 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. The improved developer solutions generally include a standard organic solvent composition and an additive composition having higher polarity and / or hydrogen bonding properties than the standard solvent composition. In one example, the improved developer composition can include PGMEA and acetic acid. Development can be carried out for about 5 seconds to about 30 minutes, in further embodiments from about 8 seconds to about 15 minutes, and in additional 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 scope of the present disclosure.

[0077] For negative tone development, developer selection can be effectively influenced by solubility parameters for both irradiated and non-irradiated coating materials, as well as the developer's volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials. Some useful developer compositions for these organotin 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. In particular, developers can have different amounts of high-polarity or low-polarity components, which can be more specifically defined by solubility parameters. In some embodiments, the solvent blend can include at least two solvents, at least 55% by volume of one or more solvents, each independently, having a Hansen solubility parameter, δH + δP, of about 16 (J / cm). 3 ) 1 / 2 and about 0.25% by volume to about 45% by volume of one or more solvents each independently has a sum of Hansen solubility parameters ΔH+ΔP of at least about 16 (J / cm 3 ) 1 / 2 As will be described later, in the case of double bake-double development processing, the second development is performed so that the sum of the Hansen solubility parameters δH+δP is at least about 16 (J / cm 3 ) 1 / 2 The developer for negative tone patterns may contain all or a greater proportion of solvents that are, or a positive tone developer may be used in the second step of negative tone patterning.

[0078] It has also been discovered that solventless development, also known as dry development, can be used with organotin materials. Dry development can involve selective removal of irradiated or non-irradiated areas of a photoresist, for example, by exposing the material to a suitable plasma or a suitable flowing gas. Dry development of organotin resists is described in PCT Publication No. 2020 / 132281A1 to Volosskiy et al., entitled "Dry Development of Resists," and U.S. Patent Application Publication No. 2023 / 0100995 to Cardineau et al., entitled "High Resolution Latent Image Processing and Thermal Development," both of which are 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 small molecule reactant that promotes removal of the irradiated or non-irradiated areas. Development can be followed by an optional rinsing step to further remove unwanted material from the pattern; such methods are described in U.S. Patent Application Publication No. 2020 / 0124970 to Kocsis et al., entitled "Patterned Organometallic Photoresists and Methods of Patterning," which is incorporated herein by reference. In the context of DBDD, dry development can be used for one (first or second) development step or both development steps.

[0079] The potential effects of additives on solubility are discussed above. These effects can be further exploited using DBDD processes for either negative or positive tone patterning. In the context of positive tone patterning, at least a significant portion of the irradiated additive-containing material can be removed by the developer during the first development step. A second bake step can be performed at a higher temperature to promote further dealkylation in the partially irradiated areas, increasing the polarity of the material and therefore its solubility in the developer used in the second development step.

[0080] As mentioned above, the additive can be a photoacid generator (PAG), a quencher, or a mixture thereof. PAGs, which generate acid in response to light adsorption, are known in the photolithography field. While PAGs generally can absorb at UV and EUV wavelengths, the presence of the PAG in a Sn-based matrix, which already has high EUV absorbance, means that the EUV light available to the organotin patterning composition is not significantly attenuated by the presence of the PAG. PAGs can also generate acidic protons in response to secondary electrons generated from EUV absorption. Evidence herein suggests that the released acidic protons facilitate the removal of organic species from the irradiated patterning composition, presumably related to the release of cleaved R groups from their bonds with tin. Meanwhile, quenchers neutralize the acidic protons. Although quenchers can also release acidic protons, these can be effectively neutralized by the quencher alkali anion.

[0081] After completion of the development step, including optional rinsing, the coating material can be heat-treated to further condense, dehydrate, densify, or remove residual developer from the material. While this heat treatment may be particularly desirable for embodiments in which the oxide coating material is incorporated into a final device, it may also be desirable to perform the heat treatment for some embodiments in which the coating material is used as a resist and ultimately removed, if stabilization of the coating material is desired to facilitate further patterning. In particular, baking the patterned coating material can be performed under conditions that result in the patterned coating material exhibiting a desired level of etch selectivity. In some embodiments, the patterned coating material can be heated to a temperature of about 100°C to about 600°C, in further embodiments from about 175°C to about 500°C, and in additional embodiments from about 200°C to about 400°C. Heating can be performed for at least about 1 minute, in other embodiments from about 2 minutes to about 1 hour, and in further embodiments from about 2.5 minutes to about 25 minutes. Heating can be performed in air, vacuum, or an inert gas atmosphere such as Ar or N2. A person of ordinary skill in the art will recognize that additional ranges of thermal treatment temperature and time within the explicit ranges above are contemplated and are within the present disclosure. Similarly, non-thermal treatments, including blanket UV exposure or exposure to oxidizing plasmas, such as O, can also be used for similar purposes.

[0082] In the context of DBDD, PEB is, in some sense, divided into two process steps: a first bake step and a second bake step after the first development. In the context of DBDD, the first PEB can be performed at a temperature of about 45°C to about 200°C, in additional embodiments about 60°C to about 175°C, and in further embodiments about 85°C to about 150°C. The second PEB after the first development can be performed at a temperature of about 145°C to about 250°C, in further embodiments about 150°C to about 225°C, and in other embodiments about 160°C to about 200°C. In addition, the second PEB step is generally performed at a temperature at least about 5°C higher than the first PEB temperature, in further embodiments about 10°C to about 100°C higher than the first PEB temperature, and in some embodiments about 15°C to about 85°C higher than the first PEB temperature. The PEB temperature should be selected low enough to avoid thermal decomposition unrelated to irradiation, which can result in loss of contrast. Generally, any post-exposure bake can be independently carried out for at least about 0.1 minute, and in further embodiments from about 0.5 minutes to about 30 minutes, and in additional embodiments from about 0.75 minutes to about 10 minutes. 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. Additional bake-develop cycles can be included, if desired.

[0083] To further improve the positive-tone patterning performance of the compositions described herein, a double-bake, double-develop (DBDD) process can be used. In such a DBDD process, a first PEB is performed after EUV irradiation to stabilize and lightly densify the material. The first PEB can be followed by a first development with aqueous base to remove the irradiated material. The first PEB promotes the formation of highly polar and low-density dealkylated Sn species in the irradiated areas of the film, which can improve the removal of material in such areas in an aqueous base developer. A second bake can then be performed at the same or higher temperature as the first PEB, followed by a second development with aqueous base. The second bake can further promote the radiolysis-induced thermal decomposition (i.e., dealkylation) of lightly exposed materials, such as those near feature edges that receive intermediate doses, to form more polar but lightly condensed Sn species that can be better removed during the second development with aqueous base.

[0084] The DBDD process can enable the initial removal of irradiated materials with high solubility in aqueous developers. During EUV exposure and the first PEB, Sn-C bonds are broken and associated organic groups are liberated from the film (i.e., dealkylated), driving a polarity change in the material. Initially, the organotin material is relatively non-polar and hydrophobic due to the presence of organic groups in the film. After EUV exposure, the first bake, and the liberation of the organic groups, the irradiated material is converted to a more polar, hydrophilic material. In intermediate dose regions, such as near feature edges where the aerial image of the radiation is blurred, incomplete dealkylation and / or condensation can occur, generating partially soluble species. Therefore, a second PEB may be desirable to further dealkylate the material in the partially soluble regions and increase its polarity, thereby enhancing its solubility in aqueous base in the second development step. In other words, the second PEB and second development can improve the positive tone contrast of the pattern. The second developer may be the same or a different positive tone developer relative to the first positive tone developer. As noted above, positive tone developers are generally aqueous alkaline (base) solutions.

[0085] For negative-tone patterning, the first development removes the unirradiated material. A second bake step at a higher temperature promotes further condensation via radiation-induced thermal decomposition of the unsolubilized but partially irradiated material to form a partially condensed, soluble material. As a result, the second development step can be carried out using a developer containing an acid or a base. Suitable second acidic developers can include aqueous or organic solvents. Developers containing an organic solvent and an organic acid, such as acetic acid, formic acid, or other carboxylic acid, are described in the above-cited '627 application. Aqueous developers containing an acid or a base generally include positive-tone developers, such as TMAH, which do not strip the patterned material due to the strengthening of the irradiated material after the second bake step. The expected sharpening of the pattern edges is reflected in Figure 9, further described above. For negative development using DBDD, the second developer generally differs from the first developer and can include an acid or a base in the Bronsted sense in an aqueous or non-aqueous solvent.

[0086] EUV lithography typically utilizes short wavelength light and is used for very small resolution features. Patterning for device formation typically leverages an initial pattern that can be effectively formed on a substrate. The pattern can include a variety of features, such as stripes, posts, or holes. While negative tone patterning has proven most effective so far for very small, high-resolution stripes (i.e., line / space patterns) using organotin resists, negative tone patterning of holes is more challenging. In particular, for negative tone patterning of holes, the area around the hole is inevitably irradiated so that the hole is surrounded by irradiated material. Therefore, the material within the hole may be exposed to shot noise photons and / or secondary electrons emitted from the irradiated material surrounding the hole, which can lead to problems with residue in the hole after negative tone development. As disclosed in the examples below, organotin patterning materials can be used with the improved positive tone imaging disclosed herein to effectively pattern holes with low residue.

[0087] In some embodiments including stripes, adjacent linear segments of adjacent structures can have an average pitch (half pitch) of about 60 nm or less (30 nm half pitch), in some embodiments about 50 nm or less (25 nm half pitch), and in further embodiments about 34 nm or less (17 nm half pitch). Pitch can be assessed by design and confirmed by scanning electron microscopy (SEM), such as top-down imaging. Patterns can be assessed using, for example, a Hitachi CG5000 CD-SEM instrument. As used herein, pitch refers to the spatial period, or the center-to-center distance between repeating structural elements; as commonly used in the art, half pitch is half the pitch. Feature dimensions of a pattern can also be described in terms of the average width of the features, which are generally assessed away from corners, etc. Linewidths are also referred to as critical dimensions (CDs), and the critical dimensions can be used to assess the available feature size for a particular dose. In the case of holes on a grating, the corresponding critical dimension is the hole diameter. Features can also refer to gaps between material elements and / or material elements. In some embodiments, the average width may be about 25 nm or less, in further embodiments about 20 nm or less, and in additional embodiments about 15 nm. A person of ordinary skill in the art will recognize that additional ranges of pitch and average width within the explicit ranges above are contemplated and are within the scope of the present disclosure. Based on these processes, patterning can generally be adapted to form various devices, such as electronic integrated circuits, through repeated patterning processes to form appropriate layered structures, such as transistors or other components.

[0088] Wafer throughput is a substantial limiting factor in the implementation of EUV lithography in high-volume semiconductor manufacturing and is directly related to the dose required to pattern a given feature. However, while chemical strategies exist to reduce imaging dose, a negative correlation between the imaging dose required to print a target feature and feature size uniformity (e.g., LWR) is typically observed for EUV photoresists at feature sizes and pitches below 50 nm, thereby limiting final device operability and wafer yield. Photoresist sensitivity can be expressed by its dose-to-gel value, and imaging dose requirements can be evaluated by creating an array of exposed pads where the exposure time is stepped from pad to pad to vary the exposure dose. The film can then be developed, and the remaining resist thickness can be evaluated for all pads, for example, using spectroscopic ellipsometry. Measured thicknesses can be normalized to the maximum measured resist thickness and plotted against the logarithm of the exposure dose to form a characteristic contrast curve. The maximum slope of the normalized thickness vs. log dose curve is defined as the photoresist contrast (γ), and the dose value at which a tangent drawn through this point equals 1 is the photoresist gel dose (D g ) for positive tone development, the contrast curve typically shows a decrease in thickness after development with increasing dose. However, as the dose is further increased, the oxide-hydroxide network further condenses and becomes insoluble, resulting in an increase in thickness after development. Thus, in positive tone patterning of organotin photoresist compositions, there are two transition regions, the first region showing a decrease in thickness and the second region showing an increase in thickness. Each transition region is characterized by a function of γ and D. gThe slopes of the curves can be characterized by values ​​of σ, where the slopes change sign relative to each other. Therefore, these terms can be defined equivalently for the two parts of the curve. In this way, common parameters used to characterize photoresists can be estimated according to Mack, C. Fundamental Principles of Optical Lithography, John Wiley & Sons, Chichester, UK; pp. 271-272, 2007. EUV image analysis is further described in P. De Bisschop and E. Hendrickx, "Stochastic effects in EUV lithography," Proc. SPIE 10583, Extreme Ultraviolet (EUV) Lithography IX, 105831K (19 March 2018); https: / / doi.org / 10.1117 / 12.2300541, which is incorporated herein by reference. [Example]

[0089] General photoresist preparation: All photoresist solutions described in the following examples were prepared by dissolving and mixing appropriate masses of tBuSn(OtAm)3 precursor and MeSn(OtAm)3 precursor in the solvent system described in Table 1 to achieve a molar ratio of 80% tBuSn:20% MeSn for all photoresist solutions. Prior to adding the organotin precursors, the solvent system was further mixed with a water source to contain approximately 300 ppm water using the method described in the '876 patent. Appropriate masses of additives described in Table 2 were then added and thoroughly mixed to form photoresist solutions with an Sn concentration of approximately 0.04 M.

[0090] [Table 1]

[0091] [Table 2]

[0092] Additive-enhanced solution compositions were prepared by adding the appropriate mass of each additive to form precursor coating samples with desired additive to Sn (A:Sn) molar ratios of 0.01, 0.02, and 0.05 (i.e., 1 mol%, 2 mol%, and 5 mol%, respectively). The target concentrations are summarized in Table 3 below.

[0093] [Table 3]

[0094] Common coatings and treatments: Silicon wafers with a 10 nm thick spin-on-glass (SOG) layer were used as substrates. Each photoresist sample was deposited using spin coating, resulting in a 20 nm thick photoresist film. After deposition, the wafers underwent a post-application bake (PAB) on a hotplate at various temperatures before EUV exposure.

[0095] To generate contrast curves, patterned exposures to EUV radiation were performed in an ASML NXE3400C EUV scanner operating in an open frame (i.e., no patterning within the pads) to generate arrays of pads exposed at different doses. The exposed wafers then underwent a post-exposure bake (PEB) at selected temperatures between 100°C and 200°C. The exposed film was then developed for 30 seconds in a 2.38 wt% TMAH (aqueous) solvent to develop the latent image into a positive-tone pattern. That is, the exposed portion of the coating was removed using a developer solvent. The film was then rinsed with HO and spin-dried. A final post-development hotplate bake at 250°C in air for 1 minute was performed to densify the pattern. The remaining thickness of each exposed pad was measured by ellipsometry, and the values ​​were plotted against the logarithm of the exposure dose to generate a characteristic contrast curve for each film sample.

[0096] Example 1: Additive A1 Film, Patterning, and Contrast Curve This example presents contrast curves for organotin oxide hydroxide photoresist compositions and shows the effect of inclusion of a PAG additive (A1) and the effect of PAG additive concentration and post-exposure bake (PEB) temperature on the processing window for positive tone development of the photoresist composition.

[0097] A series of photoresist films (1, 2, 3, and C) were prepared from precursor-coated samples 1, 2, 3, and C, respectively. After deposition, the films underwent PAB at 100°C for 60 seconds. After EUV exposure, films 1, 2, and 3 were each subjected to PEB at 120°C, 140°C, 160°C, 180°C, or 200°C for 60 seconds. Film C underwent PEB at 180°C for 60 seconds. Contrast curves were generated for each sample according to the above method and are plotted in Figures 10A-10F.

[0098] Figures 10A-10E show the contrast curves for additive-containing films prepared from Samples 1, 2, and 3 at PEB temperatures of 120°C, 140°C, 160°C, 180°C, and 200°C, respectively. Considering the results for each PEB temperature, it can be seen that the width of the low-film-thickness region of the contrast curve generally increases with increasing concentration of Additive A1. This indicates increased solubility of the exposed film and an expanded processing window for positive-tone patterning. In general, the presence of the additive increases the positive-tone process window by pushing the negative-tone transition region toward higher doses and the positive-tone transition region toward lower doses.

[0099] Figure 10F shows the contrast curves for film samples 1, 2, and 3, alongside control sample C, which contained no additive. All film samples depicted in Figure 10F were subjected to PEB at 180°C. An expansion of the processing window was observed with increasing the additive molar ratio (PAG:Sn) from 0 to 0.05. The arrows in Figure 10F indicate increasing additive concentration. As explained in the detailed description above and shown in Figure 7, this example shows that the presence of the A1 additive provided an increase in the upper limit of the dose range capable of clearing exposed resist, even at the lowest concentration ratio. This increase in the upper limit of the dose range was most pronounced for film sample 3, the sample with the highest PAG additive molar ratio. When considering the lower limit of the dose range capable of clearing exposed resist, the additive concentration effect is similarly evident, although less pronounced than at higher dose ranges.

[0100] This study demonstrates a clear positive correlation between increasing PAG additive concentration in organometallic photoresist compositions and widening the positive tone processing window. This study also demonstrates that the processing window for A1 additive-containing compositions can be tailored by adjusting the PEB temperature.

[0101] Example 2: Additive A4 Film, Patterning, Contrast Curve, and Improvement of Radiation-Induced Thermal Decomposition This example demonstrates the effect of post-exposure bake conditions on the processing window for positive tone development of organometallic photoresist compositions containing PAG additive A4.

[0102] A series of photoresist films were prepared from precursor-coated Sample 10. After deposition, the films underwent PAB at 100°C for 60 seconds. After EUV exposure, each film underwent PEB at 120°C (Sample 10A), 140°C (Sample 10B), 160°C (Sample 10C), or 180°C (Sample 10D) for 60 seconds. Control Film C was prepared from precursor-coated Sample C as described above and underwent PEB at 180°C. Contrast curves were generated for Samples 10A-10D according to the method described above and are plotted in Figure 11A.

[0103] Figure 11A shows the contrast curves corresponding to Samples 10A-10D. The arrows in Figure 11A indicate the direction of increasing PEB temperature for the samples. Figure 11A shows the generally expected effect of PEB temperature on the gel dose, D0, and the curve corresponding to the film's contrast increases at higher doses. The PAG additive-containing films also showed other PEB temperature effects. In particular, as the PEB temperature increased, the dose associated with the transition of the exposed material from soluble to insoluble (to the right of the contrast curve) decreased. The transition from soluble to insoluble material is thought to be associated with condensation of the exposed material at a given dose. After the transition, condensation of the exposed material inhibits removal by a positive-tone developer. The contrast curves for Samples 10A-10D show that increasing the PEB temperature not only lowers the upper dose limit of the solubility window, but also lowers the lower dose limit of the solubility window. The increase in the lower solubility dose limit is thought to be associated with radiolytically induced thermal decomposition, as discussed below. At 180°C PEB (sample 10D), both ends of the contrast curve shift significantly to lower doses. Figure 11A also shows that PEB temperature affects the field thickness of the exposed film, with higher PEB temperatures reducing film thickness loss ("top loss") in the lower dose region.

[0104] Figures 11B-11D compare the contrast curves of Samples 10B-10D with those of Control Film C, respectively. The comparisons in Figures 11B-11D show that when the PEB temperature is lower than 180°C, the A4 additive increases the process window (the dose range below the contrast curve) on the high-dose side of the contrast curve. This suggests that the additive functions as a condensation inhibitor. Referring to Figure 11D, at a PEB temperature of 180°C, the presence of Additive A4 shifts the entire curve to lower doses. Importantly, the transition region on the low-dose side of the contrast curve is shifted to lower doses while still exhibiting similar contrast to the non-additive Composition C. These effects of the additive enable high-contrast positive-tone processing at lower doses than the control.

[0105] To understand the effect of Additive A4 on the patterning behavior of the resist compositions, Fourier transform infrared (FTIR) spectroscopy was used to analyze the CH absorption of the films as a function of EUV dose and PEB. Resist precursor coating samples 10, 11, and C were individually spin-coated onto silicon wafers under conditions that resulted in approximately 20 nm thick films. After deposition, each wafer underwent a post-deposition bake at 100 °C for 60 seconds to complete drying of the samples. The wafers were then exposed using an ASML TwinScan NXE 3400 exposure tool by creating an array of open-frame exposure pads at different doses across the wafer. The wafers then underwent a post-exposure bake at either 160 °C or 180 °C for 60 seconds. After the post-exposure bake, each pad on each wafer was analyzed using FTIR spectroscopy to determine the peak area (2800 cm) corresponding to the absorbance of the CH stretch. -1 ~3000cm -1 The area of ​​the exposed area (area of ​​the exposed area) was measured to determine the amount of carbon remaining in each pad. The measured peak area was then normalized to the peak area of ​​an unexposed area on the same wafer to calculate the relative peak area (i.e., normalized alkyl content). The normalized alkyl content for each sample was plotted against dose, as shown in Figure 12.

[0106] As shown in Figure 12, at both PEB temperature conditions, the resist compositions containing Additive A4 (films a and b) exhibit lower normalized alkyl content at all doses compared to the control film (c). In other words, after exposure to EUV radiation and subsequent baking, the photoresist films containing Additive A4 lose more carbon at a given dose than the photoresist films without the additive. The results show that at a PEB temperature of 180°C, the normalized alkyl content of the additive-containing films (a and b) is approximately 30 mJ / cm. 2 At a PEB temperature of 160°C, a more gradual decrease in normalized alkyl content occurs for the additive-containing films (a and b), reaching an asymptotic level at a dose of approximately twice that of the comparative film exposed to a PEB of 180°C (approximately 60 mJ / cm). 2 ) reaches an asymptotic level. Figure 12 shows that the normalized alkyl content of the photoresist film prepared without the additive (film c) was less sensitive to PEB temperature and also reached the asymptotic level of normalized alkyl content more slowly compared to films a and b containing the PAG additive. Further considering sample 10D, the leftward shift in the contrast curve (Figure 11D) seems to suggest that significant dealkylation promotes resist condensation at lower doses. This effect does not appear to be completely offset by the presence of the additive. The results of this study suggest that Additive A4 enhances the radiation-induced thermal decomposition behavior of organotin photoresists, potentially resulting in more hydrocarbon emissions during post-exposure thermal processing compared to additive-free compositions. Therefore, improved radiation-induced thermal decomposition may lead to higher resist sensitivity, corresponding to the potential for lower-dose processing.

[0107] The data presented in this example demonstrate that the presence of a PAG additive in a photoresist can improve the efficiency of the radiation-induced thermal decomposition process by improving the amount of thermal decomposition (i.e., the release of organic moieties from the material) during the post-exposure bake (PEB) process. For example, the combination of a PAG additive with a sufficiently high PEB temperature can achieve improved positive-tone patterning at lower doses, while at sufficiently high temperatures, thermal decomposition can occur independently of radiation, resulting in thickness loss at low doses. For this resist composition containing PAG additive A4, positive-tone patterning can be achieved at a lower dose and a PEB temperature of 180°C compared to a resist composition without the additive at the same temperature. The presence of a PAG additive in an organometallic resist composition has been shown to contribute to various positive-tone patterning improvements across a range of processing conditions.

[0108] Example 3: Additive A2 and A3 Films, Patterning, and Contrast Curves This example presents contrast curves for organotin oxide hydroxide photoresist compositions and shows the effect of including a quencher additive (A2 or A3) and the effect of additive concentration and post-exposure bake (PEB) temperature on the processing window for positive tone development of the photoresist composition.

[0109] A series of photoresist films (Films 4-9 and C) were prepared from Samples 4-9 and C, respectively. After deposition, the films underwent PAB at 100°C for 60 seconds. After EUV exposure, each of Films 4-9 underwent PEB at 120°C, 140°C, 160°C, 180°C, or 200°C for 60 seconds. Film C underwent PEB at 180°C for 60 seconds. Contrast curves were generated for each sample according to the method described above and are plotted in Figures 13A-13F (Additive A2) and 14A-14F (Additive A3).

[0110] Figures 13A-13E show the contrast curves for films prepared from Samples 4, 5, and 6 at PEB temperatures of 120°C, 140°C, 160°C, 180°C, and 200°C, respectively. Figures 14A-14E show the contrast curves for films prepared from Samples 7, 8, and 9 at PEB temperatures of 120°C, 140°C, 160°C, 180°C, and 200°C, respectively. Considering the results for each PEB temperature, it can be seen that the width of the low-film-thickness region of the contrast curves generally increases with increasing additive concentration. This indicates an increase in the solubility of the exposed film and an expansion of the processing window for positive-tone patterning. Note the logarithmic scale on the x-axis and refer to Figure 13D. The processing window expanded approximately threefold when the additive molar ratio increased from 0.01 (Film 4) to 0.05 (Film 6). In general, the presence of the additive increases the positive tone process window by pushing the negative tone transition region to higher doses and the positive tone transition region to lower doses.

[0111] Figure 13F shows the contrast curves for film samples 4, 5, and 6, along with the additive-free control sample C. All film samples depicted in Figure 13F were subjected to PEB at 180 °C. An expansion of the processing window was observed with increasing the molar concentration ratio of the A2 additive (additive:Sn) from 0 to 0.05. The arrows in Figure 13F indicate increasing additive concentration. This example demonstrates that the presence of the A2 additive, even at the lowest concentration ratio, provided an increase in the upper dose range (higher doses in the curve) at which exposed resist could be removed. The improvement in processing window with the addition of the quencher additive is believed to be related to the quencher preventing resist condensation, resulting in the resist maintaining solubility at higher doses. This increase in the higher-dose processing window for positive-tone patterning was most pronounced for film sample 6, the sample with the highest quencher-additive concentration ratio. Film Sample 6 showed some reduction in contrast and some increase in top loss, but the additive facilitated a much wider dose window than the control Film C, which contained no additive.

[0112] Referring to Figure 14F, an expansion of the processing window was observed with increasing the concentration ratio of the A3 additive (additive:Sn) from 0 (Film C) to 0.05 (Film 9). The arrows in Figure 14F indicate increasing additive concentration. Notably, this example shows that the presence of the A3 additive, even at the lowest concentration ratio, provided an increase in the upper limit of the dose range capable of removing exposed resist (high dose increase in the curve). Importantly, the A3 additive was shown to provide a wider process window (especially at the highest additive concentration ratio) while exhibiting contrast comparable to that of Film C without the additive. Note the logarithmic scale of the x-axis; the process window for Film 9 was approximately 2.5 times wider than that of Film C without the additive.

[0113] Comparing the patterning performance of films containing the A2 additive (Figures 13A-13F) and the A3 additive (Figures 14A-14F), the results suggest that films containing the A3 additive reduce top loss more than films containing the A2 additive. This difference is most evident at higher additive concentrations and / or lower PEB temperatures. Top loss is related to the (unintended) solubility of unexposed regions in positive-tone developers. The A3 additive contains fluorinated phenyl groups, whereas the A2 additive does not. The results suggest that the fluorinated phenyl groups in the A3 additive contribute to reducing top loss.

[0114] This study shows a clear positive correlation between increasing quencher additive concentration and expanding the high-dose processing region. The results suggest that quenchers can be used to expand the dose window for positive-tone development while maintaining high photoresist contrast. The results also suggest that fluorinated quenchers may be particularly useful.

[0115] Example 4: Double bake double develop (DBDD) processing This example describes an improved method for positive-tone processing of additive-free organotin photoresists. The improved method uses two PEBs at two different temperatures and two development steps.

[0116] A series of photoresist films was prepared from precursor-coated Sample C. Each photoresist sample was deposited using spin coating, as described above, to yield a photoresist film approximately 20 nm thick. After deposition, each wafer underwent a post-apply bake at 100 °C for 60 seconds to complete drying of the sample. The wafers were exposed using an ASML TwinScan NXE 3400 exposure tool by creating an array of open-frame exposure pads at different doses across the wafer. The samples then underwent a first PEB for 60 seconds at a selected temperature between 100 °C and 180 °C, followed by a first development with 2.38% TMAH (aqueous). The samples then underwent a second PEB for 60 seconds at a selected temperature between 100 °C and 180 °C, followed by a second development with 2.38% TMAH (aqueous). Finally, the wafers were baked at 250 °C for 1 minute to densify the pattern.

[0117] Figure 15 shows the contrast curves for control samples (Films C1–C4) processed by the DBDD process at a first PEB temperature of 100°C (Film C1), 140°C (Film C2), or 160°C (Film C3) and a second PEB temperature of 180°C. Additionally, the contrast curve for the control sample (Film C) processed with a single PEB and development at 180°C is also plotted in Figure 15. The samples processed according to the DBDD process (Films C1–C3) exhibited a wider process window than the sample processed using a single PEB and a single PEB temperature (Film C). Due to the hydrophobicity of the unexposed resist film and its insolubility in aqueous developers, the first PEB temperature can effectively set the dose for the negative-tone transition region (the right side of the contrast curve). Higher PEB temperatures and radiation doses correspond to increased condensation and densification of the oxide-hydroxide network in the irradiated areas of the photoresist. Referring again to Figure 15, Film C1 processed with a first PEB temperature of 100°C and a second PEB of 180°C exhibits a wide process window, as significantly more irradiated material is removable by the first development than samples processed with higher first PEB temperatures. Figure 15 also shows that PEB temperature affects the field thickness of the exposed film, with higher PEB temperatures resulting in less film thickness loss in the lower dose region ("top loss") compared to Film C1.

[0118] This study shows that a double bake double develop process can lead to an improvement in the positive tone process window.

[0119] Example 5: DBDD Treatment with Additive Composition This example describes an improved method for positive-tone processing of organotin photoresists. The improved method combines the use of an additive-containing photoresist composition with the use of a double-bake, double-develop (DBDD) process. The DBDD process includes two post-exposure bake (PEB) steps at different temperatures and a development step after each PEB bake.

[0120] A series of photoresist films was prepared from precursor coating sample 5 (corresponding to additive-containing film samples S1–S3) and control precursor coating sample C (corresponding to additive-free film sample S). Each coating sample was deposited using spin coating, as described above, to obtain a photoresist film approximately 20 nm thick. After deposition, each wafer underwent a post-apply bake at 100°C for 60 seconds to complete drying of the sample. The wafers were then exposed using an ASML TwinScan NXE 3400 exposure tool by creating an array of open-frame exposure pads at different doses across the wafer. Film samples S2 and S3 then underwent a first PEB at 160°C for 60 seconds, followed by a first development with 2.38% TMAH (aqueous). Film samples S2 and S3 then underwent a second PEB at either 180°C (S2) or 200°C (S3) for 60 seconds, followed by a second development with 2.38% TMAH (aqueous). Film samples S and S1 were subjected to a single PEB at 180°C for 60 seconds, followed by a first development with 2.38% TMAH (aqueous). Finally, the wafers were baked at 250°C for 1 minute to densify the pattern by thermally driven condensation.

[0121] FIG. 16 shows the contrast curves of additive-containing film samples processed using the DBDD process with a first PEB temperature of 160°C and a second PEB temperature of 180°C (S2) or 200°C (S3). FIG. 16 also shows the contrast curve of additive-containing film sample S1 processed with a single bake at 180°C and a single develop. FIG. 16 also shows the contrast curve of additive-free film S processed with a single bake at 180°C and a single develop. As shown in FIG. 16, the additive-containing film samples exhibit an improved positive tone process window when processed using the DBDD process (S2 and S3) compared to additive-free film sample S and additive-containing film sample S1 processed using the single PEB and single develop process. The results indicate that the process window can be expanded for films prepared from precursor coating sample 5 using the DBDD process and a second PEB at a higher temperature.

[0122] These results suggest that the first PEB at 160°C determines the solubility of the exposed material in the high-dose region of the contrast curve, allowing for significant removal of the irradiated material during the subsequent first development step. Furthermore, the results suggest that by performing the second PEB at a higher temperature than the first PEB, the second PEB can promote further dealkylation of the exposed resist material in the lightly exposed regions. The second PEB can then promote further removal of such material in the second development process, thereby lowering the dose at which the exposed material transitions from insoluble to soluble (left side of the contrast curve). The DBDD process demonstrates an improved positive-tone process window for additive-enhanced compositions compared to when samples were processed with a single PEB and single development process.

[0123] This study demonstrates that a double-bake, double-develop process can be effectively used to improve the positive tone processing window for additive-enhanced organometallic photoresist compositions.

[0124] Example 6: Positive-tone contact hole patterning This example demonstrates the use of an additive-containing organometallic photoresist composition to enhance contact hole patterning. The additive in this example is quencher-type Additive A2.

[0125] A series of photoresist films were prepared from precursor coating samples 4 and 5 and control precursor coating sample C. Each coating sample was deposited using spin coating, resulting in a photoresist film approximately 20 nm thick. After deposition, each wafer underwent a post-apply bake at 100°C for 60 seconds to complete drying of the sample. The wafers were then exposed using an ASML TwinScan NXE 3400 exposure tool to form a hexagonal array of holes with a vertical pitch of 38 nm and a horizontal pitch of 66 nm. The film samples then underwent a PEB at 160°C or 180°C for 60 seconds, followed by development with 2.38% TMAH (aqueous). Finally, to densify the patterns, the wafers were baked at 250°C for 1 minute. CD-SEM images were then collected and analyzed for each patterned film to determine the dose, critical dimension (CD), and LCDU (local critical dimension uniformity) values ​​of each contact hole pattern. In this context, the CD value is the average diameter of the holes, and LCDU is the standard deviation of the average diameter. The EUV dose for each contact hole pattern is shown as the first number in the inset of each image.

[0126] FIG. 17 shows CD-SEM images of contact hole patterns prepared as described above. Referring to FIG. 17, contact hole patterns under the column header "Control" were prepared from control precursor coated Sample C. Contact hole patterns under the column headers "Sample 4" and "Sample 5" were prepared from precursor coated Samples 4 and 5, respectively. The results show that improvements in sensitivity and LCDU were obtained for Samples 4 and 5 compared to the control sample. For PEB at 180°C, the dose for Samples 4 and 5 was 53 mJ / cm for the control sample. 2compared with 51 mJ / cm 2 and 46 mJ / cm 2 Similarly, the LCDU values ​​obtained with the 180°C PEB for the contact hole patterns created with precursor-coated Samples 4 and 5 (4.4 nm and 4.1 nm, respectively) were lower than the control (5.7 nm). The results suggest that the wider positive-tone process window of the additive sample allows for improved contact hole patterning with positive-tone development. Comparing the results for Samples 4 and 5, which underwent a 160°C PEB versus a 180°C PEB, it is observed that the 160°C PEB bake dose was higher for both Samples 4 and 5, but the LCDU values ​​were lower. The LCDU of Sample 4 decreased from 4.4 nm to 3.3 nm when processed at the lower PEB temperature. Similarly, the LCDU of Sample 5 decreased from 4.1 nm to 3.6 nm when processed at the lower PEB temperature.

[0127] This example demonstrates that the inclusion of a quencher in an organometallic resist composition can improve positive tone patterning of contact holes.

[0128] Example 7: Patterning of positive-tone contact holes by DBDD process This example demonstrates the use of an additive-containing organometallic photoresist composition and a double bake-double develop (DBDD) process to enhance contact hole patterning. The additive in this example is quencher-type Additive A2.

[0129] A series of photoresist films were prepared from precursor coating sample 5. Each coating sample was deposited using spin coating, resulting in a photoresist film approximately 20 nm thick. After deposition, each wafer underwent a post-apply bake at 100°C for 60 seconds to complete drying of the sample. The wafers were then exposed using an ASML TwinScan NXE 3400 exposure tool to form a hexagonal array of holes with a vertical pitch of 38 nm and a horizontal pitch of 66 nm. The samples then underwent a first PEB at 160°C for 60 seconds, followed by a development with 2.38% TMAH (aqueous). The samples then underwent a second PEB at 180°C or 200°C for 60 seconds, followed by a second development with 2.38% TMAH (aqueous). Finally, the wafers were baked at 250°C for 1 minute to densify the pattern. CD-SEM images were then collected for each patterned film to determine the dose, critical dimension (CD) and LCDU values ​​at different doses.

[0130] Figure 18 shows CD-SEM images of contact hole patterns obtained using the DBDD process and additive-containing photoresist film, along with the associated dose, CD, and LCDU values. The results show that a lower dose was required to form the contact hole pattern using the additive-containing photoresist film and DBDD process compared to the conventional single PEB / single develop process. For example, returning to Figure 17, the control contact hole pattern (first column) was obtained using a precursor coating sample without additives, a single 180°C PEB, and a dose of 53 mJ / cm. 2 Conversely, as shown in Figure 18, when additive-containing precursor coating Sample 5 was used in the DBDD process, the second PEB at 180 °C yielded 44 mJ / cm 2 , and 39 mJ / cm for the second PEB at 200 °C. 2Furthermore, when additive-containing precursor coating sample 5 is used in a DBDD process, contact hole patterns with improved or comparable LCDU values ​​(4.1 nm and 5.8 nm) are obtained compared to the control sample (5.7 nm) using a single PEB and single development.

[0131] This study demonstrates that a double-bake-double-develop process can be effectively used to improve the positive-tone contact hole patterning of additive-enhanced organometallic photoresist compositions.

[0132] Example 8. Patterning of positive tone contact holes This example demonstrates the use of an additive-containing organometallic photoresist composition to enhance contact hole patterning.

[0133] A series of photoresist films were prepared from the precursor coating samples according to Table 4. Each coating sample was deposited using spin coating, resulting in a photoresist film approximately 20 nm thick. After deposition, each wafer underwent a post-apply bake at 100°C for 60 seconds to complete drying of the sample. The wafers were then exposed using an ASML TwinScan NXE 3400 exposure tool to form a hexagonal array of holes with a vertical pitch of 38 nm and a horizontal pitch of 66 nm. The film samples then underwent a PEB at 160°C or 180°C for 60 seconds, as shown in Table 5, followed by development with 2.38% TMAH (aqueous). Film samples D1 and D2 further underwent a second PEB at 180°C and 200°C for 60 seconds, respectively, followed by a second development with 2.38% TMAH (aqueous). Finally, the wafers were baked at 250°C for 1 minute to densify the pattern. CD-SEM images were then collected and analyzed for each patterned film to determine the critical dimension (CD) of each contact hole pattern. Film samples A and E were prepared without additive. Film samples B1-D1 and H1-H2 contained additive A2. Film samples F1-G2 contained additive A3.

[0134] [Table 4]

[0135] Figures 19 and 20 show CD-SEM images of the final patterned film products, and Table 5 summarizes the dose and measured CD values ​​for each patterned film. The additive-containing films generally yield contact holes with increased clearing in the holes and no shrinkage compared to the additive-free films (A and E). In particular, images of samples B1 and H1 show a combination of improved hole clearing, lower dose, and lower linewidth roughness compared to the respective additive-free control samples (A and E) processed under the same conditions. D1 and D2 (Figure 15) show CD-SEM images of patterns formed using a second bake and second development after a first bake and first development. In both cases, the second bake was at a higher temperature than the first bake. Both samples received a dose of 36 mJ / cm. 2 Comparing C1 (PEB 180°C) and D1 (PEB 160°C / PEB 180°C) exposed at 1000 W / cm², the increase in CD from 23.28 nm to 24.99 nm and the decrease in LCDU from 5.85 nm to 4.98 nm indicate that the double bake-double develop process may lower the patterning dose and aid in contact hole clearing. This result suggests that the first, lower temperature PEB lightly condenses the exposed material, which is then removed in the first development step, while the second, higher temperature PEB further condenses the remaining exposed material, which is then removed in the second development step. This double bake-double develop process appears to render more exposed material soluble, as evidenced by the improved hole clearing in D1 compared to C1.

[0136] [Table 5]

[0137] The results of this study are particularly noteworthy because they demonstrate that quenchers can be used to effectively realize the process advantages inherent in contact hole patterning using positive tone development: development of a latent contact hole image with positive tone patterning involves exposure of a regular hole pattern and clearing of exposed material from the regular hole pattern, which makes it less prone to defects than negative tone patterning of contact holes.

[0138] This example demonstrates that the inclusion of a quencher in an organometallic resist composition can improve positive tone patterning of contact holes.

[0139] It should be understood that in the above disclosure, certain terms are used interchangeably. For example, one skilled in the art would understand that the terms "coating," "layer," and "film" are intended to convey the same idea unless expressly stated otherwise.

[0140] The above-described embodiments are intended to be illustrative and not limiting. Additional embodiments are within the scope of the following claims. In addition, while the present invention has been described with reference to specific embodiments, those skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present invention. Any incorporation by reference of the above documents is limited so as not to incorporate subject matter contrary to the explicit disclosure herein. To the extent that particular structures, compositions, and / or processes are described herein with components, elements, ingredients, or other classes, the disclosure herein should be understood to extend to particular embodiments that may include additional features that do not alter the basic nature of the subject matter, as suggested in the discussion, and to embodiments that include particular components, elements, ingredients, other classes, or combinations thereof, as well as embodiments that consist essentially of such particular components, ingredients, ingredients, other classes, or combinations thereof, unless otherwise specifically stated. As will be understood by those skilled in the art, the use of the term "about" herein refers to the degree of error in measurement of the particular parameter, unless expressly stated otherwise.

Claims

1. A method for patterning a radiation-sensitive material on a substrate, Developing a material on a substrate based on a latent image in the material having an irradiated region and a non-irradiated region to form a physically patterned material on the substrate, wherein the development includes contacting the material with an aqueous alkaline liquid, and the material before irradiation is R ｎ SnO ｘ (OH) ４－ｎ－２ｘ The development comprises an organotin composition represented by 0.5 ≤ n < 3, 0 < x < 1.5 (wherein R comprises a hydrocarbyl ligand having 1 to 31 carbon atoms) and an additive (A) in a molar ratio of A:Sn of about 0.002 to about 2, wherein the additive comprises a photoacid generator, a quencher, or a mixture thereof, the additive comprises an onium ion or a zwitterion, and the development comprises selective removal of the irradiated area. Methods that include...

2. The method according to claim 1, wherein the additive comprises an electron capture agent.

3. The method according to claim 1 or 2, wherein the additive comprises an aromatic group.

4. The method according to claim 1, wherein the additive comprises a fluorinating group.

5. The method according to claim 1, wherein the onium ion comprises a cation formed from a core atom of Group 15 to Group 17.

6. The method according to claim 1, wherein the onium ion comprises an iodonium cation, a sulfonium cation, an ammonium cation, a phosphonium cation, or a mixture thereof.

7. The method according to claim 1, wherein the additive comprises an organic iodonium hydroxide compound, an organic sulfonium hydroxide compound, or a mixture thereof.

8. The method according to claim 1, wherein the additive can absorb secondary electrons and / or UV radiation to produce a soluble reaction product.

9. The method according to claim 1, wherein the additive does not significantly reduce the absorption of EUV radiation by the organotin composition.

10. The method according to claim 1, wherein the additive has an organic functional group and the additive is hydrophobic.

11. The method according to claim 1, wherein the additive is soluble in at least several organic solvents.

12. The aforementioned additive is given by formula: 【Chemistry 1】 The method according to claim 1, comprising a composition represented by the following:

13. The aforementioned additive is given by formula: 【Chemistry 2】 The method according to claim 1, comprising a composition represented by the following:

14. The aforementioned additive is given by formula: 【Transformation 3】 The method according to claim 1, comprising a composition represented by the following:

15. The aforementioned additive is given by formula: 【Chemistry 4】 The method according to claim 1, comprising a composition represented by the following:

16. The method according to claim 1, wherein the aqueous alkaline liquid comprises a quaternary ammonium hydroxide composition.

17. The method according to claim 16, wherein the aqueous alkaline liquid comprises about 0.5 to about 30 weight percent of the quaternary ammonium hydroxide composition.

18. The method according to claim 1, wherein the aqueous alkaline liquid comprises tetramethylammonium hydroxide (TMAH).

19. The method according to claim 1, wherein the contact between the material and the aqueous alkaline liquid is carried out for about 5 seconds to about 30 minutes.

20. The method according to claim 1, wherein R comprises a methyl ligand, an i-propyl ligand, a t-butyl ligand, a t-amyl ligand, or a combination thereof.

21. The method according to claim 1, wherein the hydrocarbyl ligand is branched and / or comprises an unsaturated bond, an aryl group, and / or a heteroatom.

22. The method according to claim 1, wherein the hydrocarbyl ligand is substituted with one or more fluorine atoms and / or iodine atoms.

23. The method according to claim 1, wherein 0.75 < n < 2, and R comprises a mixture of different hydrocarbyl ligands each independently having 1 to 31 carbon atoms.

24. The method according to claim 1, wherein the material in the non-irradiated region includes an organotin hydroxide network.

25. The aforementioned material is of the formula RSnO ｘ (OH) ３－２ｘ The method according to claim 1, comprising a composition represented by the formula 0 < x < 1.

5.

26. A: The method according to claim 1, wherein Sn is approximately 0.005 to approximately 0.

4.

27. The method according to claim 1, wherein the material is exposed to and baked at a temperature of at least about 80°C before development.

28. The method according to claim 1, further comprising heating the material on a substrate to a temperature of about 120°C to about 225°C based on a latent image in the material before development.

29. The method according to claim 1, further comprising exposing the radiation-sensitive material on a substrate to a pattern of EUV radiation before development to form the latent image within the material.

30. The aforementioned radiation is approximately 1 mJ / cm². ２ ~Approx. 100mJ / cm ２ The method according to claim 29, having a dose of the above.

31. The method according to claim 1, wherein the physically patterned material on the substrate comprises a line / space pattern having a half-pitch of less than about 25 nm, or a pattern of holes on a grid having a CD of less than about 35 nm, and the substrate comprises a silicon wafer.

32. The method according to claim 1, wherein the additive includes a photoacid generator.

33. The method according to claim 1, wherein the additive includes a quencher.

34. The method according to claim 1, wherein the additive comprises a photoacid generator and a quencher.

35. A radiation-patternable structure comprising a substrate and a radiation-sensitive material on the substrate, wherein the radiation-sensitive material comprises a composition represented by the formula R ｎ SnO ｘ (OH) ４－ｎ－２ｘ , where 0.5 ≦ n < 3 and 0 < x < 1.5, and a quencher (A) in a molar ratio of A:Sn of about 0.002 to about 2, the quencher comprising an onium cation and an anion which is a conjugate base for a weak acid, the radiation-patternable structure.

36. The quencher comprises an electron capture agent, and the radiation-patternable structure is as described in claim 35.

37. The quencher is a radiation-patternable structure according to claim 35 or 36, comprising an aromatic group.

38. The quencher is a radiation-patternable structure according to claim 35, comprising a fluorinating group.

39. The radiation-patternable structure according to claim 35, wherein the radiation-sensitive material further comprises a photoacid generator.

40. The radiation-patternable structure according to claim 35, wherein the onium cation comprises a cation formed from core atoms of Groups 15 to 17.

41. The radiation-patternable structure according to claim 35, wherein the onium cation includes iodonium cation, sulfonium cation, ammonium cation, phosphonium cation, or a combination thereof.

42. The radiation-patternable structure according to claim 35, wherein the quencher can absorb secondary electrons and / or UV radiation to produce a soluble reaction product.

43. The radiation-patternable structure according to claim 35, wherein the quencher does not significantly reduce the absorption of EUV radiation by the organotin composition.

44. The radiation-patternable structure according to claim 35, wherein the quencher has an organic functional group and the quencher is hydrophobic.

45. The quencher is a radiation-patternable structure according to claim 35, which is soluble in at least some organic solvents.

46. The aforementioned quencher is given by the formula: 【Transformation 5】 A radiation-patternable structure according to claim 35, comprising a composition represented by .

47. The aforementioned quencher is given by the formula: 【Transformation 6】 A radiation-patternable structure according to claim 35, comprising a composition represented by .

48. The radiation-patternable structure according to claim 35, wherein R comprises a hydrocarbyl ligand having 1 to 32 carbon atoms.

49. The radiation-patternable structure according to claim 35, wherein R comprises a methyl ligand, an i-propyl ligand, a t-butyl ligand, a t-amyl ligand, or a combination thereof.

50. The radiation-patternable structure according to claim 48, wherein the hydrocarbyl ligand is branched and / or comprises an unsaturated bond, an aryl group, and / or a heteroatom.

51. The radiation-patternable structure according to claim 48, wherein the hydrocarbyl ligand is substituted with one or more fluorine atoms and / or iodine atoms.

52. The radiation-patternable structure according to claim 48, wherein R comprises a mixture of different hydrocarbyl ligands each independently having 1 to 31 carbon atoms.

53. The radiation-patternable structure according to claim 35, wherein the radiation-sensitive material comprises an organotin hydroxide network.

54. The radiation-sensitive material on the substrate is of the formula RSnO ｘ (OH) ３－２ｘ The radiation-patternable structure according to claim 35, comprising a composition represented by the formula (wherein 0 < x < 1.5).

55. A: The radiation-patternable structure according to claim 35, wherein Sn is approximately 0.005 to approximately 0.

5.

56. The radiation-patternable structure according to claim 35, wherein the radiation-sensitive material on the substrate has an average thickness of about 1 nm to about 50 nm, and the substrate includes a silicon wafer.

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