Organotin patterning materials with silicon / germanium-bearing ligands, precursor compositions and methods of synthesis

Abstract

As described herein, the photosensitive composition comprises RSnL3, where R is a hydrocarbyl ligand having 1-20 carbon atoms and one or more silicon and / or germanium heteroatoms, and L is an acetylide ligand (-C≡CA, where A is a silyl group having 0-6 carbon atoms or an organo group having 1-10 carbon atoms). A method is described in which the photosensitive composition is synthesized by reacting RX, where X is a halide, with MSnL3, where M is an alkali metal, alkaline earth metal, or pseudo-alkaline earth metal, and L is an acetylide or dialkylamide. The radiation sensitive composition is useful for radiation-based patterning, such as with EUV light.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to co-pending U.S. Provisional Patent Application No. 63 / 210,769 to Jilek et al., filed June 15, 2021, entitled "Organotin Patterning Materials: Compositions and Methods," which is incorporated herein by reference, and claims priority to co-pending U.S. Publication No. 17 / 682,639 to Jilek et al., filed February 28, 2022, entitled "Organotin Patterning Materials with Ligands Having Silicon / Germanium; Precursor Compositions; and Synthesis Methods."

[0002] The present invention relates to compositions of monoorganotin triamides, monoorganotin triacetylides or monoorganotin trioxides, in which the organo groups are defined as hydrocarbyls containing Si or Ge heteroatoms. The present invention further relates to hydrolysis products, synthesis of the compositions and methods of performing radiation patterning. [Background technology]

[0003] Organometallic compounds provide metal ions in solution and vapor form for deposition of thin films. Organotin compounds offer high EUV absorption and radiation sensitive tin-ligand bonds that can be used to pattern thin films by lithography. The fabrication of semiconductor devices with ever shrinking dimensions by EUV radiation requires new materials with wide process latitudes to achieve the required patterning resolution and low defect density. Summary of the Invention [Means for solving the problem]

[0004] In a first aspect, the present invention relates to improved photosensitive compositions RSnL3, where R is a hydrocarbyl ligand having 1-20 carbon atoms and one or more silicon or germanium heteroatoms. L forms a hydrolyzable Sn-L bond. In some embodiments, L is an acetylide ligand (-C≡CA, where A is a silyl group having 0-6 carbon atoms or an organo group having 1-10 carbon atoms, such as a phenyl group). In further embodiments, the photosensitive composition comprises (R 4 )3Si(CH2) n CR 5 2- (wherein n is 0 to 8, R 4 and R 5 is independently a hydrogen, a halide, or a hydrocarbyl group having 1 to 4 carbon atoms), and L is a hydrolyzable ligand.

[0005] In a further aspect, the present invention relates to a method for the production of RSnL3, where R is a hydrocarbyl group having 1-20 carbon atoms and one or more silicon or germanium heteroatoms, and L is a hydrolyzable ligand. The method comprises reacting RX, where X is a halide, with MSnL3, where M is an alkali metal, alkaline earth metal, or pseudo-alkaline earth metal. Typically, L is an acetylide (C≡CA, where A is a silyl group having 0-6 carbon atoms or an organo group having 1-10 carbon atoms, such as a phenyl group) or a dialkylamide having 1-10 carbon atoms, and the reaction forms RSnL3 having an Sn-C bond, where R is a hydrocarbyl ligand having 1-20 carbon atoms and one or more silicon and / or germanium heteroatoms.

[0006] In a further aspect, the present invention relates to RSnL3 compositions and formulations thereof as solution-based precursors for the deposition of radiation-sensitive thin film photoresists.

[0007] In a further aspect, the invention relates to a method of forming a coating comprising the photosensitive composition.

[0008] In a further aspect, the present invention relates to a method of irradiating and developing a coated thin film to produce a nanostructured pattern. The method of patterning an organometallic compound comprises forming a coating on a substrate, comprising depositing RSnL3, where R is a hydrocarbyl group having 1-20 carbon atoms and one or more silicon or germanium heteroatoms, and L is a hydrolyzable ligand, irradiating the coating with radiation to form a latent image, and developing the image to form a patterned coating having nanoscale features according to the latent image. [Brief description of the drawings]

[0009] [Figure 1] This is a plot of the 119Sn NMR spectrum of ethyltrimethylsilyltin tris(trimethylsilylacetylide) [(CH3)3SiCH2CH2Sn(TMSA)3]. [Diagram 2] This is a plot of the 1H NMR spectrum of ethyltrimethylsilyltin tris(trimethylsilylacetylide) [(CH3)3SiCH2CH2Sn(TMSA)3]. [Diagram 3] FIG. 1 is a plot of the 119Sn NMR spectrum of ethyltrimethylsilyltin tris(tert-butoxide) (CH3)3SiCH2CH2Sn(OC(CH3)3)3. [Figure 4] 1H NMR spectrum plot of ethyltrimethylsilyltin tris(tert-butoxide) (CH3)3SiCH2CH2Sn(OC(CH3)3)3. [Diagram 5] 1 is a plot of film thickness versus spin speed for an E-TMS resist formulation. [Figure 6] 1 is a plot of the contrast curves for E-TMS resist processed at selected post-exposure bake temperatures. [Figure 7] A set of electron microscope images of line-space patterns of E-TMS resist processed at selected post-exposure bake temperatures. [Figure 8] 1 is a plot comparing normalized FTIR CH absorbance versus bake temperature for films formed with E-TMS resist formulations and reference resist formulations. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Organotin compositions have been synthesized containing organic ligands with silicon / germanium atoms that offer the potential for greater radiation absorption and greater ligand stability prior to irradiation to facilitate radiation-based patterning. The compounds are prepared as precursors containing hydrolyzable ligands that can undergo hydrolysis to form a patternable layer. The precursor compounds generally have a single carbon-tin bond that is susceptible to radiation cleavage upon irradiation to form a fictitious image. Organic ligands that form C-Sn bonds include Si or Ge substituents such as silyl groups, (CH3)3SiCH2CH2SnL3 being illustrative. The suitability of the compounds for EUV patterning is demonstrated in the following examples.

[0011] Organometallic photoresists, especially those based on organotin materials, function as high performance EUV photoresists that can enable the patterning of high resolution, high fidelity patterns. These materials can generally be operated as negative tone photoresists, where the irradiated areas remain after development, or as positive tone photoresists, where the irradiated areas are selectively removed during development.

[0012] Radiation-sensitive organotin compositions useful as high-resolution and high-sensitivity photoresists have been described by Meyers et al. in U.S. Pat. No. 9,310,684, entitled "Organometallic Solution Based High Resolution Patterning Compositions," and U.S. Pat. No. 10,228,618, entitled "Organotin oxide hydroxide patterning compositions, precursors, and patterning" (hereinafter the '618 patent), both of which are incorporated herein by reference. In general, radiation-sensitive organotin compositions include organic ligands bonded to Sn atoms via Sn-C and / or Sn-carboxylate bonds. The present disclosure describes new silicon / germanium-rich organotin compositions that have been discovered, which may exhibit improved patterning and processing over non-rich organotin compositions.

[0013] It is believed that exposure of organotin materials to EUV radiation and subsequent processing can cleave Sn-C bonds and allow the formation of new Sn-O-Sn and Sn-OH bonds in the irradiated areas. After fragmenting the S-C bonds, the increased concentration of Sn-O-Sn and S-OH bonds results in more condensed hydrophilic material compared to the unexposed material, thereby creating a large chemical development contrast between the irradiated and unirradiated areas. To take advantage of this contrast, it is desirable to identify new materials that expand the lithographic process window and improve the fidelity of the patterned structures. This process window can be expanded, for example, by replacing carbon atoms in the organic ligands with high atomic number heteroatoms such as silicon or germanium.

[0014] It has been discovered that the substitution of carbon atoms with silicon or germanium atoms in the hydrocarbyl groups of monoalkyltin photoresists can improve their thermal stability and expand their lithographic process window. The compositions described herein are useful as precursors for forming radiation patternable coatings and for converting the precursors to other useful compositions, such as compositions containing different hydrolyzable ligands or cluster-like compositions having Sn-O-Sn bonds. As noted above, the photosensitivity of organotin materials arises from the nature of the Sn-C bond, and therefore it is generally desirable for the Sn-C bond to remain intact during processing from precursor to coating.

[0015] Hydrolyzable ligands have little effect on photosensitivity since they are generally hydrolyzed prior to irradiation to form oxo-hydroxo rich coatings with Sn-OH and / or Sn-O-Sn bonds. Hydrolyzable ligands are generally selected to provide synthetic advantages and desired processing, such as further purification, deposition mode, stability, handling, etc. Similarly, the availability of convenient synthetic routes is important.

[0016] Silicon and germanium are in the same group of the periodic table as carbon. Therefore, silicon and germanium can have similar chemical structures and other properties, but also differences due to their higher atomic mass. Therefore, silicon and germanium can form alternative hydrocarbon-like structures and corresponding moieties in side groups off carbon-based hydrocarbyl ligands. Here, particularly interesting compounds have one or more silicon / germanium atoms in the hydrocarbyl structure extending from a carbon atom directly bonded to a tin atom.

[0017] As described herein, hydrolyzable ligands can be reacted in the following ideal reaction: RSnL3+2H2O→RSnOOH+3HL (1) to form organotin oxide hydroxide (or organotin oxide hydroxide hydrate) compositions.

[0018] Some examples of suitable hydrolyzable ligands (L) are -NR'2, -OR', or -CCR', where R' is a silyl group or a hydrocarbyl group having up to 12 carbon atoms. Some examples of L include, but are not limited to, -NMe2, -NEt2, -OnPr, -OiPr, -OtBu, -OtAmyl, -CC(Si(CH3)3)[trimethylsilylacetylide] (TMSA), -CC(CH5)[phenylacetylide], and the like. R is R1R2R3C-, where R 1 is a hydrocarbyl group or a silyl group containing at least one silicon atom, and R 2 , R 3 are independently H, X (halides), a silyl group, or a hydrocarbyl group that may or may not contain silicon atoms, where R may contain a total of 1-20 carbon atoms. In precursors incorporating silicon / germanium, particularly interesting embodiments herein include those having the structure: -CR' n (CH2) m (SiR'') o in which o is 1-3, m is 0-2, n is 0-2, n+m+o=3, and R′ and R″ (both independently of each other and the other members of the R′ and R″ moieties) are H or hydrocarbyl groups having 1-3 carbon atoms.

[0019] The applicant has developed several techniques for synthesizing and purifying a series of RSnL3 compounds. The methods offer significant advantages, particularly fewer polyalkyl contaminants, good yields, and the use of more readily available reactants. Desired results have been achieved. In this case, the alkylating agent can be a Grignard reagent, a diorganozinc reagent, or a monoorganozinc amide. Such synthesis can directly produce monoalkyltin triamides with reduced polyalkyl contaminants that can be used to form resists or can be further purified to further reduce contaminant levels. In the synthesis method, the alkylating agent selectively replaces the amide group of the tin tetraamide with an alkyl group. In some embodiments, the reaction selectively produces monoalkyltin triamides with reduced polyalkyltin contaminants, particularly reduced dialkyltin contaminants. The described synthesis method improves the selectivity and yield of monoalkyltin triamides by limiting the formation of dialkyltin by-products. The method is particularly useful for branched alkyl systems. The monoalkyltin triamides with reduced polyalkyl contaminants can then be used to form monoalkyltin trialkoxides with reduced polyalkyl contaminants. Such improved synthesis techniques are described in U.S. Patent Application Publication No. 2019 / 0315781 to Edson et al., entitled "Monoalkyl Tin Compounds With Low Polyalkyl Contamination, Their Compositions and Methods," which is incorporated herein by reference.

[0020] Further synthetic techniques have been developed to obtain the desired yields and purity in practical applications for a broader range of organic ligands forming C-Sn bonds. In these synthetic reactions, hydrocarbyl ligands are generated from organic halide reactants. Organic halide reactants are easily available for a broad range of compounds to provide the ligands. Other synthetic techniques may be generally applicable for the synthesis of a range of hydrocarbyl ligands, but there may be practical constraints regarding reactant composition and yields to introduce the ligand, reaction time, selection of suitable solvents, and possibly other practical constraints. These reactions have been designed to form either trialkylamine hydrolyzable ligands (e.g., RSn(NR'2)3) or triacetylide hydrolyzable ligands (e.g., RSn(CCR')3). The synthesis of alkali metal tin compounds provides effective intermediates that may be useful in other situations. These techniques have been adapted to the synthesis of silicon-containing compounds described herein and are illustrated below. Such synthesis techniques are described in more detail for a range of hydrocarbyl ligands in co-pending U.S. Patent Application Publication No. 17 / 410,316 to Edson et al., entitled "Methods to Produce Organotin Compositions With Convenient Ligand Providing Reactants" (hereinafter the '316 application), which is incorporated herein by reference. For products with significant vapor pressure, it may be desirable to purify the product via vacuum distillation or, optionally, fractional distillation designed to achieve high purity. See U.S. Patent Application Publication No. 2020 / 0241413 to Clark et al., entitled "Monoalkyl Tin Trialkoxides and / or Monoalkyl Tin Triamides With Low Metal Contamination and / or Particulate Contamination and Corresponding Methods," which is incorporated herein by reference.The products may also be reacted to form derivatives such as organotin trialkoxides, which may be further purified by the techniques described above and other means known in the art.

[0021] A somewhat similar but less desirable synthetic approach to that described in the '316 application is described in U.S. Patent Application Publication No. 2022 / 0002323 to Ermert et al., entitled "Process for Preparing Organotin Compounds," which is incorporated herein by reference. In the process of the '323 application, a less than stoichiometric amount of lithium dialkylamide is added. As a result, a dihalo tin dimer with two bridging amide ligands precipitates as a by-product. Based on observed side reactions, the maximum yield based on tin is 0.5. In applicant's method, stoichiometric tin by-products are not formed as contaminants.

[0022] Hydrolysis of the above RSnL3 compositions can result in hydroxide- and oxide-rich products in which two or more RSn moieties are condensed to form Sn-O and Sn-OH bonds, e.g., "football" clusters (RSn). 12 O 14 (OH)8 and related intermediate compositions. As described below, hydrolysis of the present RSnL3 compositions can be used to make radiation patternable coatings that include a network of oxo-hydroxo ligands attached to Sn atoms with Sn-OH and Sn-O-Sn linkages. To form radiation patternable coatings, hydrolysis can occur during or after coating formation, but typically prior to irradiation. Coatings can be deposited using solution or vapor approaches.

[0023] R is the carbon bonded to the tin atom. 3 or sp 2R forms a carbon-tin bond that is hybridized, and R contains at least one silicon atom, and may optionally contain unsaturated or aromatic carbon-carbon moieties and / or other heteroatoms that are neither carbon nor hydrogen. As noted above, for convenience and consistency in the art, R may be referred to interchangeably as an alkyl ligand, an organic ligand, or a hydrocarbyl ligand, including the corresponding substituents and bonding structures.

[0024] In some embodiments, the hydrocarbyl ligand is a aryl group such that (after hydrolysis of the hydrolyzable ligand) the compound is R 1 R 2 R 3 CSnO (2-(z / 2)-(x / 2)) (OH) x (In the formula, R 1 contains silicon / germanium atoms and 0-10 carbon atoms, R 2 and R 3 are independently hydrogen or a hydrocarbyl group having 1 to 10 carbon atoms, and in some embodiments, R 1 R 2 R 3 It may be desirable for some patterning compositions to have a hydrocarbyl ligand R that can be generally represented as R 1 R 2 R 3 It is equally applicable to other embodiments including CSn(L)3, where L corresponds to a hydrolyzable ligand, such as an alkoxide (hydrocarbyl oxide), acetylide, or amide moiety. In some embodiments, R 2 and R 3 is capable of forming a cyclic alkyl moiety, and R 1 may also be attached to other groups in the cyclic moiety. Suitable branched ligands include, for example, (R 2 and R 3 is methyl and R 1 is a silyl group), (R 1 is a silyl group, R 2 is methyl and R 3 is -CH2CH3) and (R 1is silyl, and R 2 is methyl or -CH2CH3, and R 3 is hydrogen). 1 is (CH3)3SiCH2- and R 2 and R 3 is hydrogen, and other related embodiments are described below. In other embodiments, the hydrocarbyl group may include an aryl or alkenyl group, such as a benzyl or allyl or alkynyl group. In further embodiments, suitable R groups may include hydrocarbyl groups substituted with non-silicon / germanium heteroatom functional groups, including cyano, thio, ether, keto, ester, or halogenated groups, or combinations thereof. In accordance with conventions in the art, the hydrocarbyl group may be referred to as an alkyl group even if the group has unsaturated bonds, aryl groups, heteroatoms, and the like.

[0025] In some embodiments, R is (R 4 )3Si(CH2) n CR 5 2- (wherein n is 0 to 8, or in further embodiments, n is 0 to 3 or 0 to 2; R 4 and R 5 are independently hydrogen or a halide (F, Cl, Br, or I) or a hydrocarbyl group having 1 to 4 carbon atoms. In some embodiments, R 4 is hydrogen, a methyl group (-CH), or ethyl (-CHCH). In some embodiments, n is 0 to 2, and R 5 is methyl and R 4 is a methyl group (-CH3) or ethyl (-CH2CH3). In such ligands, R 2 , R 3 (In the above notation) are both R 5 An example has R equal to (CH3)3SiCH2CH2-.

[0026] For use in patterning compositions, it may be desirable to convert the product containing a trialkamide or triacetylide ligand to an organotin trialkoxide. As described further below, this reaction is generally carried out after purification by distillation via reaction with the corresponding alcohol, although in some embodiments it may be appropriate to form the alkoxide directly without first purifying the triamide or triacetylide. The product organotin trialkoxide is generally an oil or low melting solid that can be purified via distillation. Such steps are described further below and outlined in the examples below for specific products. Although conversion of the precursor composition to a trialkoxide is not required to form a coating precursor, organotin trialkoxides may be convenient precursors for deposition because the products after hydrolysis and coating formation are innocuous, such as alcohols.

[0027] After preparation of the desired organotin precursor, the precursor can be dissolved in a suitable solvent, such as an organic solvent, such as alcohols, aromatic and aliphatic hydrocarbons, esters, or combinations thereof, to prepare a precursor solution. In particular, suitable solvents include, for example, aromatics (e.g., xylene, toluene), ethers (anisole, tetrahydrofuran), esters (propylene glycol monomethyl ether acetate, ethyl acetate, ethyl lactate), alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, methanol, isopropyl alcohol, 1-propanol), ketones (e.g., methyl ethyl ketone), mixtures thereof, and the like. In general, the choice of organic solvent can be influenced by solubility parameters, volatility, flammability, toxicity, viscosity, and potential chemical interactions with other processing materials. After the components of the solution are dissolved and combined, the nature of the species can change as a result of partial in situ hydrolysis, hydration, substitution, and / or condensation.

[0028] The organotin precursor can be dissolved in a solvent at a concentration that provides a suitable concentration of Sn to form a coating of appropriate thickness for processing. The concentration of the species in the precursor solution can be selected to achieve the desired physical properties of the solution. Lower overall concentrations can result in desirable solution properties, especially for certain coating approaches such as spin coating where thinner coatings can be achieved with reasonable coating parameters. It may be desirable to use thinner coatings to achieve ultra-fine patterning and reduce material costs. Generally, the concentration can be selected as appropriate for the selected coating approach. Coating properties are further described below. Generally, the tin concentration includes from about 0.005M to about 1.4M, in further embodiments from about 0.02M to about 1.2M, and in other embodiments from about 0.1M to about 1.0M. A person of ordinary skill in the art will recognize that additional ranges of tin concentrations within the ranges explicitly stated above are contemplated and are within the present disclosure.

[0029] In some embodiments, the improved photosensitive precursor composition comprises R n SnL 4-n and its hydrolysates, where R is selected from the various moieties detailed herein and explicitly detailed above, the various components of the blended precursor composition may or may not be the same. Such blended solutions can be tuned for optimization of various performance requirements such as solution stability, coating uniformity, patterning performance, etc. Blended compositions can be prepared by mixing two or more organotin compositions, e.g., R, with or without the use of a solvent. n SnL 4-nwhere L is a hydrolyzable ligand. For example, neat RSnL3 and neat R'SnL3 can be combined to form a blend precursor. The blend composition can then be diluted in a solvent, if desired. Alternatively, each individual organotin composition can be diluted in a desired solvent to form an identifiable organotin solution, and then each individual organotin solution can be combined to form a blend solution. In general, the hydrolyzable ligand can be the same or different for each individual organotin component throughout the blend composition. In some embodiments, the improved photosensitive composition can include at least 1 mol %. The Sn of the desired component in the blend solution is at least 10 mol % in further embodiments. The Sn of the blend solution is at least 20 mol % in further embodiments. The Sn of the blend solution is at least 50 mol % in further embodiments. The Sn of the specific desired component of the blend solution. Additional ranges of mole % of the improved photosensitive composition within the stated ranges of the blend solution are contemplated and are within the scope of the present disclosure.

[0030] The organotin compositions described herein may be useful as precursors for forming coatings via vapor deposition, generally due to their high vapor pressure. Vapor deposition methods generally include chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), and modifications thereof. In a typical vapor deposition process, the organotin compositions may be reacted with small molecule vapor-phase reagents, such as H2O, O2, H2O2, O3, CH3OH, HCOOH, CH3COOH, and the like, which serve as O and H sources for the production of radiation-sensitive organotin oxide and oxide hydroxide coatings. Organotin compositions that include alkylamides or alkoxides as hydrolyzable ligands may be particularly desirable for use in vapor deposition techniques to form organotin oxide / hydroxide coatings. Gas phase deposition of radiation patternable organotin coatings is described in PCT Application PCT / US2019 / 031618, entitled "Methods for Making EUV Patternable Hard Masks," by Wu et al., incorporated herein by reference, and in the above-cited '618 patent. The production of radiation sensitive organotin coatings can generally be accomplished by reacting a volatile organotin precursor RSnL3 with small gas phase molecules. The reaction can include hydrolysis / condensation of the organotin precursor to hydrolyze hydrolyzable ligands while leaving the Sn-C bonds substantially intact.

[0031] For an overview of a typical process for radiation-based patterning, e.g., extreme ultraviolet (EUV) lithographic processing, a photoresist material is deposited or coated as a thin film on a substrate, pre-exposure baked, exposed to a pattern of radiation to create a latent image, post-exposure baked, and then developed with a liquid, typically an organic solvent, or by dry development techniques to produce a developed pattern of resist. Fewer steps can be used if desired, and additional processes can be used to remove residues and improve pattern fidelity.

[0032] The thickness of the radiation patternable coating may depend on the desired process. For use in single patterning EUV lithography, the coating thickness is generally selected to produce a pattern with low defect rate and patterning repeatability. In some embodiments, a suitable coating thickness may be from 0.5 nm to 100 nm, in further embodiments from about 1 nm to 50 nm, and in further embodiments from about 2 nm to 25 nm. It will be understood by those skilled in the art that additional ranges of coating thickness are contemplated and are within the scope of the present disclosure. The coating thickness of radiation patternable coatings made by vapor deposition techniques is generally controllable through appropriate selection of reaction times or process cycles.

[0033] The substrate generally presents a surface onto which the coating material can be deposited, and may include multiple layers, with the surface being associated with an uppermost layer. The substrate is not particularly limited and may include any reasonable material, such as silicon, silica, other inorganic materials, such as ceramic and polymeric materials. Silicon-containing materials have been observed to have improved stability after application as radiation-sensitive coatings. This stability improvement is further described below.

[0034] Preparation of Improved Compositions Various synthesis embodiments can be adapted for synthesis based on the general concept of first synthesizing an intermediate mixture of formula MSnL3, where M is one or more (+1) or (+2) metal ions and L is a hydrolyzable ligand, specifically a dialkylamide or alkyl acetylide. Typically, the intermediate is formed at a concentration based on the tin content of about 0.005M to about 2M, in further embodiments about 0.01M to about 1.75M, and in other embodiments about 1.5M to about 0.025M. Those of skill in the art will recognize that additional ranges of concentrations within these explicit ranges are contemplated and are within the scope of the present disclosure. Reacting this intermediate with RX, where X is a halide atom, forms RSnL3, which can be further used as desired. In some embodiments, M can be Li. In other embodiments, M can be another alkali metal, such as Na, K, Rb, or Cs. In some embodiments, M may further include an alkaline earth metal, such as Mg, Ca, Sr, or Ba, along with the alkali metal. In further embodiments, M may further include a pseudo-alkaline earth ion, such as Zn, Cd, or Hg, along with the alkali metal. In some embodiments, M may be a mixture of any of the alkali metals, alkaline earth metals, or pseudo-alkaline earth metals described above. The proper selection of M may be driven by thermodynamic and / or kinetic factors, such as the electronegativity difference between M and Sn, that allow the desired alkylation (i.e., Sn-C bond formation) reaction to proceed with suitable yield and purity. An exemplary synthesis is performed with potassium K ion. Other factors that may influence the selection of a suitable M may be physical requirements, such as hazards presented by the reactants / products (e.g., pyrophoricity, toxicity) and physical properties of the reactants / products. In either case, it has been discovered that better yields and purer products can be achieved in some situations by using alternative alkali metal ions in place of or in addition to lithium, or by introducing alkaline earth or pseudo-alkaline earth ions in addition to lithium or other alkali metal ions.Although the intermediates are stable (e.g., no precipitates are formed), due to their reactivity and the resulting difficulty in isolating them, the structures of the intermediates are inferred from available measurements and a review of reasonable alternatives. Thus, the idealized formula MSnL3 can be understood to be more precisely a complex intermediate mixture, where M can include one or more metals as described above.

[0035] Without wishing to be limited by theory, it is believed that the proper selection of M may be influenced by the reactivity of the alkylation reaction between the MSnL3 intermediate (nucleophile) and RX (electrophile). For more reactive R groups, such as those with low C-Sn bond dissociation energy and / or high electrophilicity, the release of energy from the alkylation reaction is believed to contribute to the decomposition of the Sn-C bond, resulting in poor product yield. Therefore, it may be preferable for M to include a metal with higher electronegativity (i.e., lower electropositivity) to reduce the energy released when the electrophilic alkyl halide reacts with the nucleophilic MSnL3 intermediate. Conversely, for less reactive R groups, it may be desirable to select a metal with lower electronegativity (i.e., higher electropositivity) to increase the yield of the desired RSn bond.

[0036] Based on this principle, the photosensitive composition is prepared by the following reaction: RX+MSnL3→RSnL3+MX (2) RSnL3 + excess R a OH→RSn(OR a )3 where M is a metal ion (alkali, alkaline earth or pseudo-alkaline earth), X is a halide (F, Cl, Br or I) and the hydrolyzable ligand L is a dihydrocarbyl amide or an organic (hydrocarbyl or silyl) acetylide. In an illustrative embodiment, the reaction involves M=K and L=TMSA, where the reaction is RX+KSn(TMSA)3→RSn(TMSA)3+KX (3) R(TMSA)3 + excess R a OH→RSn(OR a )3 where R is a hydrocarbyl group containing one or more silicon or germanium heteroatoms as described above, X is a halide, and R a is a hydrocarbyl group having ≦12 carbon atoms (CH3)3SiCH2CH2- is a representative R group, and methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, sec-butyl, amyl and tert-amyl are R a The wide availability of R X compounds as reactants and the broad range of reactivities of the compounds in the corresponding reactions provides the ability to introduce a wide range of R ligands into the product for the formation of many monoorganotin compositions.

[0037] In general terms, heavy atom (silicon / germanium) enriched monohydrocarbyltin triamides and monohydrocarbyltin triacetylides can be prepared by the following general reaction: 3HNR'2+3MR''(+M'Z)+SnX2+RX'→RSn(NR'2)3+by-product, or 3R'CCH+3MR''(+M'Z)+SnX2+RX'→RSn(CCR')3+by-products (4) where X, X' are independently halides and R'' is generally a hydrocarbyl group having ≦10 carbon atoms. R″ becomes incorporated into a by-product, typically HR″, where its identity is generally not particularly limited or significant, and it can be selected for general availability, low cost, ease of by-product removal, and good reactivity. Some suitable examples of R″ are methyl, ethyl, propyl, n-butyl, and tert-butyl. The R′ group provides a substituent for the corresponding hydrolyzable ligand of the product composition, as described above. In such reactions, M is typically lithium, but lithium can be replaced by other alkali metals, namely, sodium, potassium, rubidium, and cesium. The M′Z in parentheses is any reactant M″OR″ or M′″X2, where M″ represents an alkali metal ion, OR″ is an alkoxide that maintains passivity, and M′″ is an alkaline earth / pseudo-alkaline earth metal ion provided as a halide, and X is a halide ion. Such reactions are further described in the '316 application cited above.

[0038] From a practical standpoint for some target products, alkali metal alkoxides (MORs) 0 ) is added to the first step of the reaction, the reaction achieves better yields and rates for the reaction. In addition, desirable reactants are those that are more readily available for such processing. Nevertheless, for some organic ligands, better yields can be obtained with the introduction of a non-lithium alkali metal compound. Thus, a further illustrative embodiment involving potassium is shown in the following general reaction: 3HNR'2+3LiR''+KOR 0 + SnX2 + RX' → RSn(NR'2)3 + by-product, or 3R'CCH+3LiR''+KOR 0 +SnX2+RX'→RSn(CCR')3+byproducts (5) In the reactions represented by these equations, potassium (K) can be replaced with other non-Li alkali metal ions. The preparation of KSn(TMSA)3 is taken from the '316 application.

[0039] At present, isolation of alkali metal tin triamides or alkali metal tin triacetylides has not been achieved. Improved synthetic techniques do not depend on the precise identity of intermediates, and the general discussion herein focuses on the total starting material and final products that can be isolated and characterized. Nevertheless, the assumed identity of the intermediates, e.g., KSn(TMSA)3, is based on strong assumptions made from the species present. In the particular solvent used, the metal ions are not expected to be fully solvated. Nevertheless, the compositions remain in solution, where large cluster formation and gelation are not observed. Without wishing to be limited by theory, organometallic reagents, e.g., alkyllithiums, alkylmagnesiums (Grignard reagents), and potassium tert-butoxide, are known to form clusters with metal-metal bonds, e.g., tetramers, hexamers, and cubanes, and therefore it is reasonable to assume that similar species form in solution, possibly complex equilibrium mixtures that have been neglected to characterize so far. In these cases, the relative stabilities of the known species suggest that it is possible to predict which intermediate species are present, but precise structural characterization is not necessary to understand their fundamental chemical participation in the reaction. The reactivity of the species appears to be consistent with the inability to isolate them by removing the solvent.

[0040] Although a general reaction is presented above, such a reaction can be carried out in multiple steps. Since one of the reactants is a tin dihalide, such as tin dichloride, the requirement for the solvent selection may involve the appropriate solubility of the tin dihalide. The other initial reactants, such as dihydrocarbylamine and monoalkyllithium (or generally monoalkylalkali metal), may be soluble in different solvents. In some embodiments, the reactants may be initially in a slurry form due to the partial solubility of the reactants. The reaction is generally carried out in an anhydrous (i.e., substantially water-free) organic solvent under an oxygen-free or depleted atmosphere, such as a nitrogen purged atmosphere, argon or other inert atmosphere. The solvent can be selected to effect the solubility of the various components. Due to the interaction of the solvent with the metal ion, the selection of the solvent may be based at least in part on the reaction rate in the selected solvent, which can be evaluated empirically. When different solvents are selected, they are generally miscible. Aprotic polar solvents such as ethers (e.g., dimethyl ether, diethyl ether), tetrahydrofuran (THF), acetone, and mixtures thereof are generally useful. Solvents should generally be selected to be inert to the reactants, intermediates, and products. For example, when multiple solvents are used to introduce distinguishable reactants, the solvents should generally be miscible with each other. The first reaction can be considered as the synthesis of the MSnL3 intermediate (wherein L is a dialkylamide (dihydrocarbylamide) or alkyl acetylide (hydrocarbyl acetylide)), but the specific structure has not been verified. From the reactants and reaction conditions, evidence suggests the formation of a tin-ligand bond, where the presence of the moiety SnL3 seems likely and the metal cation seems likely to associate with the tin moiety for stabilization, but the specific structure may exist in a complex equilibrium mixture. This first reaction can be considered, if desired, as two separate reactions, including a first sub-reaction directed to the formation of a metal-ligand composition (ML) and a subsequent sub-reaction with SnCl2 or other tin dihalide. As described in detail, M can be an alkali metal as well as an alkaline earth metal and / or a pseudo-alkaline earth metal.In general, in the first reaction, the solution is generally cooled to less than 10° C., in some embodiments to 0° C., which may be a convenient temperature for the use of an ice bath, but for non-aqueous solutions, this temperature is not unusual. The cooling allows for the desired reaction control while maintaining a reasonable reaction rate, but the cooling temperature does not have to be maintained for the entire time of the reaction. The first sub-reaction is not particularly limited and can be carried out for any practical length of time. The first sub-reaction can continue for at least about 30 seconds, in other embodiments for at least about 2 minutes, in some embodiments for 1 minute to 5 hours, in some embodiments for about 2 minutes to about 3 hours. In some embodiments, the two sub-reactions can be combined and proceed essentially as a single reaction, which is effectively a zero time first sub-reaction or a short first sub-reaction. When a non-lithium alkali metal alkoxide and / or alkaline earth (or pseudo-alkaline earth) dihalide is introduced as a reactant, this compound can conceptually be added as part of the first sub-reaction or the second sub-reaction, or optionally in connection with a third sub-reaction between the first and second sub-reactions. A person of ordinary skill in the art will recognize that additional ranges of times and temperatures within the explicit ranges above are contemplated and are within the present disclosure.

[0041] Generally, the alkyllithium reactant and the amine / acetylene reactant are approximately stoichiometric, but generally a small to medium excess of the amine / acetylene reactant is used, for example, about 1 mole percent (mol%) to about 50 mole% of the amine / acetylene reactant can be used. When a non-lithium alkyl alkali metal compound is used, a similar stoichiometric amount or ligand precursor (dialkylamine or alkylacetylene / silylacetylene) can be used. Generally, it is desirable to have the ML composition in a 3:1 ratio to the molar amount of Sn to add three ligands for each tin. When a non-lithium metal alkoxy alkali metal compound is used with an alkyllithium, the alkyllithium can have an amount based on molar equivalents to the amine / acetylene reactant and the non-alkali metal compound can have an equivalent molar amount to the tin compound added, but if desired, a larger amount of metal (alkali metal or alkaline earth metal or pseudo-alkaline earth metal) can be used as long as additional amounts of ML are not formed. The tin reactant can be added in approximately molar equivalents (1:3) to the ML ligands contributing to the reactant to form three ligand-tin bonds for each tin atom in the corresponding embodiment. The low amount of contaminants from tin by-products containing one, two, or four ligands confirms the effectiveness of the tin to ML reactant molar ratio control. The metal concentration in the reactant solution is generally about 0.025M to about 2M, and in further embodiments, about 0.5 to about 1.5M. One of ordinary skill in the art will recognize that concentration ranges and permissible stoichiometric ratios within the ranges set forth above are contemplated and are within the scope of the present disclosure.

[0042] The second reaction involves the introduction of a carbon-tin bond with the formation of an organic ligand bonded to the tin. The carbon-tin bond conceptually replaces the metal-tin bond, the metal being an alkali metal, an alkaline earth metal and / or a pseudo-alkaline earth metal. The organic ligand bonded to the tin results from reaction with an organic halide RX. Generally, at least about a stoichiometric amount of organic halide is introduced to form the carbon-tin bond, but excess organic halide can be introduced. In some embodiments, up to a three-fold molar excess of organic halide can be used in the reaction, and in further embodiments, about 1 to about 2 molar equivalents of RX per mole of Sn can be used. The solvent can be the same as that used in the first reaction, or can be selected from the same available solvents and mixtures thereof. The product of the first reaction is generally not purified before carrying out the second reaction, but by-products can be removed if convenient. The metal concentration is generally similar to that of the first reaction step, but is usually slightly lower due to dilution. Given the exothermic nature of the reaction, the second reaction is typically, but not necessarily, initiated at a lower temperature, such as about 0° C. or more typically about −78.5° C. to about 10° C., although in some embodiments, the reactants can be combined at room temperature. After mixing the reactants for the second reaction, the reaction can be allowed to continue at the same temperature or can be gradually warmed to a temperature of about 20° C. to about 50° C. or room temperature (20-24° C.). The reaction can be carried out for at least about 15 minutes, in some embodiments about 15 minutes to about 24 hours, and in some embodiments about 30 minutes to about 15 hours, although longer reaction times can be used if desired. A person of ordinary skill in the art will recognize that additional ranges of concentrations, molar ratios, temperatures and times given above for the second reaction are contemplated and are within the scope of the present disclosure.

[0043] Due to the exothermic nature of the reactions described herein, it may be beneficial to modify various parameters of the synthesis, such as reactant amounts, reaction temperature, reagent addition times, reaction time, etc. Such requirements are known to those of skill in the art. A useful analytical technique for analyzing reactions and informing the practitioner of suitable process conditions is reaction calorimetry. Calorimetry data can provide useful thermodynamic variables for a given reaction. In particular, scale-dependent variables (e.g., enthalpy heat) can be measured for a desired reaction and used to properly perform the reaction on a larger scale. Thus, process variables can be suitably controlled for reactions at different scales. Reaction calorimetry data is included in some examples of the '316 application. Within the guidelines provided above with the guidance of the examples below, those of skill in the art will know that the specific parameters for a particular reaction can be adjusted to provide the desired results. Optimization using routine experimentation can be performed by those of skill in the art based on these teachings for a wide range of product compositions. The illustrated reactions provide good yields and high specificity for the product compositions.

[0044] Once the product is formed, the organotin tri(dihydrocarbylamide / hydrocarbyl acetylide) can be purified. Purification depends on the nature of the product, but generally involves separation of the desired product from by-products and optionally any unreacted reagents. Purification may also include removing any volatile compounds, including solvents, from the product mixture by drying or exposure to vacuum. For products with significant vapor pressure, it may be desirable to purify the product via vacuum distillation or, optionally, fractional distillation designed to achieve high purity. See U.S. Patent Application Publication No. 2020 / 0241413 to Clark et al., entitled "Monoalkyl Tin Trialkoxides and / or Monoalkyl Tin Triamides With Low Metal Contamination and / or Particulate Contamination and Corresponding Methods," incorporated herein by reference. The product may also be reacted to form derivatives such as organotin trialkoxides, which may be further purified by the above techniques and other means known in the art. Purification may or may not be performed prior to forming the trialkoxide.

[0045] In some embodiments, the hydrolyzable ligand is an alkoxide. Alkoxides are particularly suitable as hydrolyzable ligands for solution processing of hydroxide oxide coatings due to their storage stability, hydrolytic sensitivity, and relatively harmless hydrolysis products, i.e., alcohols. Conversion of organotin amides and acetylides to organotin alkoxides can be accomplished by the following reaction: RSn(CCR')3+3R''OH+3NR3'''→RSn(OR'')3 where R is a hydrocarbyl group containing 1 to 10 carbon atoms and one or more silicon or germanium atoms, and R', R'' and R''' are the same or different and are generally alkyl groups containing ≦12 carbon atoms. Particularly preferred groups are methyl, ethyl, propyl, butyl, pentyl (amyl) and, where applicable, their respective isomers such as tert-butyl and tert-amyl.

[0046] In some embodiments, the photosensitive composition can be dissolved in a solvent to prepare an improved photoresist solution. Suitable solvents, of course, must include those in which the improved photosensitive composition is suitably soluble, but can be selected based on their physical properties, such as flammability, viscosity, toxicity, volatility, etc. Other requirements for a suitable solvent can be cost and potential interactions with other processing materials. Some examples of suitable solvents include alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, cyclohexanol), esters (e.g., ethyl acetate, propylene glycol monomethyl ether acetate, ethyl lactate), ethers (e.g., propylene glycol monomethyl ether), ketones (e.g., 2-heptanone, cyclopentanone, cyclohexanone, 1-butanone, 4-methyl-2-pentanone), mixtures thereof, and the like. It will be understood by those skilled in the art that other suitable solvents not explicitly listed are contemplated. The improved photoresist solution can be used to form radiation patternable coatings as described below.

[0047] In some embodiments, the improved photosensitive compositions can be partially or completely hydrolyzed prior to dissolution in a suitable solvent as described above, in which the hydrolyzable ligands of the improved photosensitive compositions are partially or completely replaced by O or OH ligands in condensed clusters containing Sn-C and Sn-O and / or Sn-OH bonds.

[0048] Radiation Patternable Coatings Radiation-patternable coatings can be formed through deposition and subsequent processing of a photosensitive composition on a selected substrate. Deposition of radiation-patternable coatings can be accomplished through a variety of means known to those skilled in the art. Particularly useful deposition techniques employing organotin materials are described in U.S. Pat. No. 10,228,618 to Meyers et al., entitled "Organotin oxide hydroxide patterning compositions, precursors, and patterning," and PCT patent application PCT / US2019 / 031618 to Wu et al., entitled "Methods for Making EUV Patternable Hard Masks," both of which are incorporated herein by reference.

[0049] When solution deposition is desired, a particularly useful solution deposition method is spin coating. Spin coating is well known in the art and can be particularly useful for photoresist processing during semiconductor manufacturing. In a typical spin coating process, a photoresist solution is delivered to the surface of a substrate, such as a Si wafer, and the substrate is rapidly spun to form a coating. During the spin coating process, the hydrolyzable tin-ligand bonds of the organotin composition can react with atmospheric water to undergo significant hydrolysis and condensation to form a coating on the substrate that includes Sn-O-Sn and Sn-OH networks along with radiation sensitive Sn-C bonds and potential interstitial water. In some embodiments, the improved photoresist solution is spin coated at a spin speed of 500 to 3000 rpm. The spin speed is not particularly limited, but is generally adjusted to produce a desired coating thickness. Generally, a slower spin speed produces a thicker coating than a faster spin speed for a given photoresist solution. The relationship between spin speed and coating thickness will be understood by those skilled in the art.

[0050] The coating thickness may also depend on the concentration of Sn in the photoresist solution. In some embodiments, the [Sn] concentration in a suitable solvent is from 0.005 to about 1.0 M, in further embodiments from about 0.01 M to about 0.5 M, and in further embodiments from about 0.05 M to about 0.1 M. It will be understood by one of ordinary skill in the art that additional ranges of [Sn] concentrations are contemplated and are within the scope of the present disclosure.

[0051] The thickness of the radiation patternable coating may depend on the desired process. For use in single patterning EUV lithography, the coating thickness is generally selected to produce a pattern with low defect rate and patterning repeatability. In some embodiments, a suitable coating thickness may be from 0.5 nm to 100 nm, in further embodiments from about 1 nm to 50 nm, and in further embodiments from about 2 nm to 25 nm. It will be understood by one of ordinary skill in the art that additional ranges of coating thickness are contemplated and are within the scope of the present disclosure.

[0052] In other embodiments, the radiation-patternable coatings can be formed via various vapor deposition methods, such as atomic layer deposition (ALD), chemical vapor deposition (CVD), physical vapor deposition (PVD), etc. Typical vapor deposition techniques generally involve reacting one or more metal-containing precursors with one or more small molecule vapor-phase reagents, such as HO, HO, O, O, or CHOH, which act as O and H sources for the generation of oxides and oxide hydroxides. Thus, hydrolyzable compounds can be directly deposited via vapor-phase hydrolysis as the corresponding alkyltin oxide hydroxide coatings, which can then be appropriately patterned.

[0053] In CVD processes, two or more reactant gases are generally mixed in the chamber near the substrate surface. Thus, sufficient stability can be designed and introduced into the reaction conditions to control undesired gas-phase reactions and nucleation. ALD precursors, which are separately and sequentially introduced into the reaction chamber, typically react with chemisorbed co-precursors or decomposition products to saturate the substrate surface. Desirable characteristics of RSnX3 precursors include, for example, sufficient volatility for gas-phase transport in the system, thermal stability to prevent premature decomposition, and suitable reactivity with co-precursors to produce the target products under the specified process conditions. Pressure and temperature in the reaction chamber can be selected to control the reaction process.

[0054] The coating thickness of radiation patternable coatings made by vapor deposition techniques is generally controllable through appropriate selection of reaction time or process cycle. The thickness of the radiation patternable coating may depend on the desired process. For use in single patterning EUV lithography, the coating thickness is generally selected to produce a pattern with low defect rate and pattern fidelity repeatability. In some embodiments, a suitable coating thickness may be from 0.5 nm to 100 nm, in further embodiments from about 1 nm to 50 nm, and in further embodiments from about 2 nm to 25 nm. It will be understood by one of ordinary skill in the art that additional ranges of coating thickness are contemplated and are within the scope of the present disclosure.

[0055] The substrate generally presents a surface onto which a coating material can be deposited, and may include multiple layers, with the surface being associated with an uppermost layer. The substrate is not particularly limited and may include any reasonable material, such as silicon, silica, other inorganic materials, such as ceramic and polymeric materials.

[0056] After deposition and formation of the radiation sensitive coating, further processing can be employed prior to exposure to radiation. In some embodiments, the coating can be heated at 30° C. to 300° C., in further embodiments at 50° C. to 200° C., and in further embodiments at 80° C. to 150° C. Heating can be carried out in some embodiments for about 10 seconds to about 10 minutes, in further embodiments for about 30 seconds to about 5 minutes, and in further embodiments for about 45 seconds to about 2 minutes. Additional ranges of temperatures and heating durations within the above explicit ranges are anticipated and contemplated. Such heating processes can be carried out under atmospheric conditions or under controlled partial pressures of gases such as H2O, CO2, CO, H2, N2, H2S, HCl, Ar, and the like, which affect the defectivity and reproducibility of the patterned structures.

[0057] The stability of radiation-sensitive coating materials can be evaluated in coatings. In particular, the thermal stability of specific R groups can be evaluated spectroscopically during a heating step prior to irradiation. The stability can be evaluated by spectroscopically measuring CH vibrations (e.g., CH stretching and bending modes (2957, 2924, 2858, 1391 and 1331 cm)) as a function of heating temperature from 50°C to 250°C, with heating carried out for 120 seconds. -1 This can be conveniently tracked using FTIR spectroscopy by summing the magnitude of the absorption associated with the 3005 cm-1 to 2765 cm -1 The stability test is estimated by calculating the area under the range of IR absorption. The decrease in infrared intensity corresponds to the loss of R groups in the coating. In general, it is desirable for the R groups to remain relatively constant in the coating up to a certain temperature above which they rapidly leave the film (i.e., decompose) giving a steep negative slope on a plot of CH absorption versus bake temperature. To evaluate films in this stability test, the temperature at which the infrared absorption falls below 95% is chosen, if an initial value is available to compare the films.

[0058] Patterning of the composition The radiation can generally be directed to the coated substrate through a mask, or the radiation beam can be controllably scanned across the substrate. Generally, the radiation can include electromagnetic radiation, electron beam (beta radiation), or other suitable radiation. Generally, the electromagnetic radiation can have a desired wavelength or range of wavelengths, such as visible radiation, ultraviolet radiation, X-ray radiation, etc. The achievable resolution of the radiation pattern generally depends on the radiation wavelength, with higher resolution patterns generally being achievable with shorter wavelength radiation. Therefore, it may be desirable to use ultraviolet light, X-ray radiation, or electron beam radiation to achieve particularly high resolution patterns.

[0059] According to the international standard ISO 21348 (2007) (incorporated herein by reference), ultraviolet light spans wavelengths from 100 nm to less than 400 30 nm. Krypton fluoride lasers can be used as 248 nm ultraviolet sources. The ultraviolet range can be subdivided in several ways under accepted standards, such as extreme ultraviolet (EUV) from 10 nm to less than 121 nm, and far ultraviolet (FUV) from 122 nm to less than 200 nm. The 193 nm line from an argon fluoride laser can be used as a radiation source for FUV. EUV light at 13.5 nm has been used for lithography, and this light is generated from Xe or Sn plasma sources excited using high energy lasers or discharge pulses. Soft x-rays can be defined as 0.1 nm to less than 5 10 nm.

[0060] Electromagnetic dosage can be characterized by a fluence or dose, which is given by the integrated radiative flux over exposure time. In some embodiments, a suitable radiation fluence is about 1 mJ / cm 2 ~about 200mJ / cm 2 and in a further embodiment about 2 mJ / cm 2 ~Approx. 150mJ / cm 2 and in a further embodiment about 3 mJ / cm 2 ~about 100mJ / cm 2 In an embodiment, the EUV radiation may be about 150 mJ / cm 2 It is possible to perform this with a dose of approximately 2 mC / cm at 30 kV.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.

[0061] Based on the design of the coating material, there may be a large contrast in material properties between the irradiated areas with condensed coating material and the unirradiated coating material with substantially intact Sn-C bonds. In embodiments where a post-irradiation heat treatment is used, the post-irradiation heat treatment can be performed at a temperature of about 45°C to about 300°C, in other embodiments about 50°C to about 225°C, and in further embodiments about 60°C to about 175°C. The post-exposure bake can generally be performed for at least about 0.1 minutes, in further embodiments about 0.5 minutes to about 30 minutes, and in other embodiments about 0.75 minutes to about 10 minutes. Those of ordinary skill in the art will recognize that additional ranges of post-irradiation bake temperatures and times within the ranges set forth above are contemplated and are within the scope of the present disclosure. Such high contrast in material properties further promotes the formation of high resolution lines with smooth edges in the developed pattern, as described in the following section.

[0062] In negative tone imaging, the developer may be an organic solvent, such as the solvent used to form the precursor solution. In general, the choice of developer may be influenced by the solubility parameters for both irradiated and unirradiated coating materials, as well as the volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials of the developer. In particular, suitable developers include, for example, alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, isopropanol, 1-propanol, methanol), ethyl lactate, ethers (e.g., tetrahydrofuran, dioxane, anisole), ketones (pentanone, hexanone, 2-heptanone, octanone), and the like. Development may be carried out for about 5 seconds to about 30 minutes, in further embodiments from about 8 seconds to about 15 minutes, and in other embodiments from about 10 seconds to about 10 minutes. One of ordinary skill in the art will recognize that additional ranges within the above explicit ranges are contemplated and are within the scope of the present disclosure. In addition to the main developer composition, the developer may include additives that aid in the development process. Suitable additives may include, for example, viscosity modifiers, solubility enhancers, or other processing aids. If any additives are present, the developer may contain up to about 10 weight percent of the additives, and in further embodiments up to about 5 weight percent of the additives. A person of ordinary skill in the art will recognize that additional ranges of additive concentrations within the explicit ranges above are contemplated and are within the present disclosure.

[0063] For weaker developers, such as dilute organic developers or compositions in which the coating has a lower development rate, a higher temperature of the development process can be used to increase the dissolution rate. For stronger developers, the temperature of the development process can be lower to reduce the development rate and control its kinetics. In general, the development temperature can be adjusted between appropriate values ​​that match the volatility of the solvent. In addition, the developer containing the dissolved coating material near the developer-coating interface can be dispersed by ultrasonic treatment during development. The developer can be applied to the patterned coating material using any reasonable approach. For example, the developer can be sprayed onto the patterned coating material. Spin coating can also be used. In automated processing, a puddle method can be used that involves pouring the developer onto the coating material in a stationary format. If desired, spin rinsing and / or drying can be used to complete the development process. Suitable rinsing solutions include, for example, ultrapure water, aqueous tetraalkylammonium hydroxide, methyl alcohol, ethyl alcohol, propyl alcohol, and combinations thereof. After developing the image, the coating material is disposed on the substrate as a pattern.

[0064] In some embodiments, a solvent-free (dry) development process may be performed through the use of a suitable thermal or plasma development process, such as that described by Tan et al. in PCT Patent Application PCT / US2020 / 039615, entitled "Photoresist Development With Halide Chemistries," incorporated herein by reference. For organotin photoresist coatings, dry development can be performed using halogen-containing plasmas and gases, such as HBr and BCl3. In some cases, dry development may offer advantages over wet development, such as reduced pattern collapse, reduced scum, and finer control over development conditions and compositions, i.e., plasma and / or etching gases.

[0065] After completion of the development step, the coating material can be heated to further dehydrate and condense the material, remove residual developer, or both. The development process generally results in the formation of nanoscale features having at least one dimension with a size below a micron and often nanoscale thickness and width. While this heat treatment can 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 in some embodiments in which the coating material is used as a resist and is ultimately removed. In particular, the step of baking the patterned coating material can be performed under conditions that produce 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 other 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, in vacuum, or in 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 temperatures and times 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 O2, can also be utilized for similar purposes. EXAMPLES

[0066] Example 1. (1) A method for preparing ethyltrimethylsilyltin tris(trimethylsilylacetylide) and (2) converting it to an alkoxide. This example relates to a synthesis based on the following two reactions to form silicon-containing alkyl ligands attached to tin via a C-Sn bond. All of the experiments described in the examples are carried out under an oxygen-depleted inert atmosphere, such as nitrogen, argon or other inert atmosphere. (1)(CH3)3SiCH2CH2Br+KSn(TMSA)3→(CH3)3SiCH2CH2Sn(TMSA)3 (2) (CH3)3SiCH2CH2Sn(TMSA)3 + excess TEA + excess t-BuOH → (CH3)3SiCH2CH2Sn(OtBu)3

[0067] (1) n-Butyllithium (2.6M in hexanes) was added to a cold (-50°C) solution of trimethylsilylacetylene in diethyl ether. After a few minutes, a slurry of SnCl2 and KOtBu in THF was added. The contents were stirred for at least 2 hours while warming to room temperature. The newly formed KSn(TMSA)3 was cooled to -50°C and a solution of bromoethyltrimethylsilane in diethyl ether was added slowly. After stirring for 16 hours, the solvent was removed in vacuo. The product was extracted with pentane and filtered to remove precipitated salts. The pentane was removed to give ethyltrimethylsilyltintris(trimethylsilylacetylide) as a waxy, low melting solid.

[0068] (2) The product from (1) was dissolved in a solution of triethylamine (TEA) and t-butanol and heated at 80 °C for 40 h. Unreacted TEA and tBuOH were removed in vacuo, and ethyltrimethylsilyltin tris(tert-butoxide) [(CH3)3SiC2H4Sn(OC4H9)3] was isolated as a liquid by distillation.

[0069] Figure 1 shows the following chemical shifts: 119 Sn NMR (149MHz, C6D6) δ-269.25ppm (CH3)3SiCH2CH2Sn(TMSA)3 119 This is the Sn NMR spectrum.

[0070] Figure 2 shows the following chemical shifts: 1 H NMR (400MHz, C6D6) δ-0.17(s,9H), 0.06(s,27H), 0.87(m,2H), 1.05(m,2H) ppm for (CH3)3SiCH2CH2Sn(TMSA)3. 1 1 H NMR spectrum.

[0071] Figure 3 shows the chemical shifts of: 119Sn NMR (149MHz, neat) δ-202.71ppm for (CH3)3SiCH2CH2Sn(Ot-Bu)3 119 This is the Sn NMR spectrum.

[0072] Figure 4 shows the chemical shifts of: 1 H NMR (400 MHz, neat) δ-0.23 (s, 9H), 0.65 (m, 2H), 1.03 (s, 27H, m, 2H) ppm for (CH3)3SiCH2CH2Sn(Ot-Bu)3 1 1 H NMR spectrum.

[0073] Example 2. Precursor Formulation To prepare 100 mL of resist solution, 1.45 mL of (CH3)3SiC2H4Sn(OC4H9)3 (FW = 439.29, ρ = 1.06 g / cm 3 ) (synthesized according to Example 1) was added to a glass container in a glove box. 4-Methyl-2-pentanol was then added to the container to produce a final Sn concentration of 0.035 M. This formulation and the coating derived therefrom described in Example 3 are referred to as E-TMS.

[0074] Example 3. Deposition of a resist coating This example describes the formation of a patterning coating based on the precursor solution of Example 2.

[0075] Circular silicon wafers with a diameter of 10.2 cm with a native oxide surface were used as substrates for film deposition. The precursors were spin-coated onto the Si wafer at 1500 RPM for 45 seconds. The wafers were then baked at selected temperatures between 100 and 180 °C for times up to 120 seconds. Film thickness after coating and baking was measured via spectroscopic ellipsometry to be approximately 20 nm. All films exhibit root-mean-square surface roughness less than 0.5 nm as measured by atomic force microscopy.

[0076] The precursors were also coated on 300 mm Si wafers at selected spin speeds on a Lithius PROZ track at the Interuniversity Microelectronics Centre (IMEC). Film thickness was measured by spectroscopic ellipsometry. Figure 5 illustrates the relationship between film thickness and spin speed.

[0077] Example 4. Contrast and Patterning contrast A 25.9±0.3 nm film of E-TMS was coated onto a SOG ("spin-on-glass", approximately 8.5 nm thick) underlayer on a silicon wafer. This film and a commercial grade Inpria reference material (YATU1011™) were exposed in an open frame, i.e., without a mask, using an EUV NXE3400C scanner operating at a wavelength of 13.5 nm. The scanner exposed an array of pads on each wafer. The wafer was baked at a selected temperature, developed with an organic solvent, and then baked at 250° C. to remove any developer residue. The thickness of each pad was then measured via ellipsometry.

[0078] FIG. 6 shows the derived contrast curves for the reference material and the E-TMS material at 140, 160 and 180° C. The following table summarizes the relevant parameters extracted from these curves. g or Dose vs. gel is the dose at which sufficient film thickness is achieved, D0 is the highest dose at thickness 0, and contrast is the ratio of D0 to D g The E-TMS material achieves sufficient thickness at a significantly higher dose than the reference material.

[0079] [Table 1]

[0080] Patterning A series of E-TMS films were deposited with a thickness of 25.6±0.3 nm on SOG-coated silicon wafers. A mask designed to print a 16P32 (16 nm line width at 32 nm pitch) pattern was employed to expose the sample films and the Inpria reference film described above on a NXE3400C EUV scanner. The exposed films were baked at various temperatures and then developed with an organic solvent. Following development, the films were baked at 250° C. to remove developer residues.

[0081] The resulting patterns were imaged on a Hitachi CG5000 CD-SEM (critical dimension scanning electron microscope) at a beam voltage of 800 V and a beam current of 8.0 pA. Figure 7 shows selected images and plots the dose (mJ / cm) for each pattern. 2 ), linewidth (CD, nm) and linewidth roughness (LWR, nm). The caption at the top of each image defines the post-exposure bake temperature. Each pattern represents the CD closest to the target linewidth (16 nm). The highest CD is shown with LWR<10 nm since the target CD was not present in the developed structures on the wafers baked at 220 and 240°C.

[0082] Example 5. Evaluation of thermal stability This example compares the thermal stability of organotin compositions with Si-substituted ligands and unsubstituted ligand compositions.

[0083] E-TMS was coated onto a group of silicon wafers according to the method of Example 3. Inpria reference material with unsubstituted hydrocarbon ligands bonded to Sn was coated onto a second group of silicon wafers. The wafers were then baked for 120 seconds at selected temperatures between 50 and 240°C. Fourier transform infrared (FTIR) transmission spectra of each film were collected on a Nicolet 6700 spectrometer using the bare substrate as background. Several hydrocarbon C-H stretching and bending modes (2957, 2924, 2858 cm) were analyzed for each spectrum. -1 ) belongs to 2765 cm -1 ~3005cm -1The CH absorbance peak areas were summed and normalized by thickness and plotted as a function of bake temperature as shown in FIG. 8. At bake temperatures above approximately 110-120°C, the CH absorbance peak area of ​​the reference film was lower than that of the E-TMS film. With increasing bake temperature, the percent difference between the peak areas increased. At 200°C, the normalized peak area of ​​the E-TMS film was about 93% and that of the reference film was about 70%. The reference film had a normalized absorbance that dropped below 95% at approximately 125°C, and the E-TMS film had a normalized absorbance that dropped below 95% at approximately 175°C. The results show that the E-TMS film is more thermally stable than the reference film. This example provides evidence of the higher thermal stability provided by organic ligands with high atomic number heteroatoms. The results suggest that the heteroatoms in the ligands stabilize the C-Sn bonds between the ligands and the Sn atoms.

[0084] The above embodiments are intended to be illustrative and not limiting. Additional embodiments are within the scope of the claims. In addition, although the present invention has been described with reference to specific embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the spirit and scope of the present invention. Any incorporation by reference of the above documents is limited to not incorporating subject matter contrary to the explicit disclosure of the present specification. Unless otherwise specified, to the extent that specific structures, compositions and / or processes are described herein with components, elements, ingredients or other parts, the disclosure of the present specification should be understood to be directed to specific embodiments, embodiments that include specific components, elements, ingredients, other parts or combinations thereof, and embodiments that consist essentially of such specific components, ingredients or other parts or combinations thereof, which may include additional features that do not change the fundamental nature of the subject matter proposed in the discussion.

Claims

1. RSnL ３ wherein R is a hydrocarbyl ligand having 1 to 20 carbon atoms and one or more silicon and / or germanium heteroatoms, and L is an acetylide ligand (-C≡CA, where A is a silyl group having 0 to 6 carbon atoms or an organo group having 1 to 10 carbon atoms).

2. 10. The photosensitive composition of claim 1, wherein the one or more silicon or germanium heteroatoms are bonded to a carbon atom that is directly bonded to a tin atom.

3. The hydrocarbyl ligand has the formula R １ R ２ R ３ C-(wherein, R １ contains a silicon or germanium atom and 0 to 10 carbon atoms; R ２ and R ３ 3. The photosensitive composition of claim 1, wherein:

4. R １ The photosensitive composition of claim 3 , wherein comprises a silyl group.

5. R ２ and R ３ The photosensitive composition of claim 3 , wherein is a methyl group.

6. 3. The photosensitive composition of claim 1 or 2, wherein R comprises a cyano, thio, ether, keto, ester, halogenated group, or a combination thereof.

7. The photosensitive composition of claim 1 or 2, wherein L comprises TMSA.

8. RSnL ３ 2. The photosensitive composition of claim 1, wherein comprises ethyltrimethylsilyltintris(trimethylsilylacetylide).

9. The RSnL ３ is the RSnL on the wafer ３ 3. The photosensitive composition of claim 1, wherein the photosensitive composition is thermally stable, retaining at least 90% of the normalized CH peak area as measured by FTIR analysis after heating at 200° C. for 120 seconds, as determined by coating with

10. A solution comprising an organic solvent and the photosensitive composition according to claim 1 or 2.

11. 11. The solution of claim 10, wherein the organic solvent comprises an alcohol, an aromatic hydrocarbon, an aliphatic hydrocarbon, an ester, an ether, a ketone, or a combination thereof, and the solution has a concentration based on stannous concentration of about 0.005 M to about 1.4 M.

12. The solution of claim 11 , wherein the organic solvent comprises 4-methyl-2-pentanol.

13. RSnL ３ (Wherein, R is (R ４ ) ３ Si(CH ２ ) ｎ CR ５ ２ - (wherein n is 0 to 8; R ４ and R ５ are independently hydrogen, a halide, or a hydrocarbyl group having 1 to 4 carbon atoms; and L is a hydrolyzable ligand.

14. n=0 to 2, and R ４ is a methyl group (CH ３ 14. The photosensitive composition of claim 13, wherein

15. 15. The photosensitive composition of claim 13 or 14, wherein L comprises an alkoxide, acetylide, amide moiety, or a combination thereof.

16. L is -NR' ２ , -OR', -CCR'', or combinations thereof, where R' is a hydrocarbyl group having up to 12 carbon atoms, and R'' is a silyl group or a hydrocarbyl group having up to 12 carbon atoms.

17. L is -NMe ２ , -NEt ２ , -OiPr, -OtBu, -OtAmyl, -CC(Si(CH ３ ) ３ 15. The photosensitive composition of claim 13 or 14, comprising:

18. R''SnL' ３ (wherein, R'' is a hydrocarbyl ligand different from R and having 1 to 20 carbon atoms, and L' is a hydrolyzable ligand the same as or different from L), the photosensitive composition according to claim 13 or 14, further comprising the same.

19. A precursor solution comprising an organic solvent and the photosensitive composition according to claim 13 or 14.

20. 20. The solution of claim 19, wherein the organic solvent comprises an alcohol, an aromatic hydrocarbon, an aliphatic hydrocarbon, an ester, an ether, a ketone, or a combination thereof, and the solution has a concentration based on stannous concentration of about 0.005 M to about 1.4 M.

21. 20. The solution of claim 19, wherein the organic solvent comprises 4-methyl-2-pentanol.

22. R''SnL'' ３ 20. The solution of claim 19, further comprising: wherein R″ is a hydrocarbyl ligand different from R and having 1 to 20 carbon atoms, and L′ is a hydrolyzable ligand that is the same as or different from L.

23. RSnL ３ wherein R is a hydrocarbyl group having 1 to 20 carbon atoms and one or more silicon or germanium heteroatoms, and L is a hydrolyzable ligand, comprising the steps of: RX (wherein X is a halide) and MSnL ３ wherein M is an alkali metal, an alkaline earth metal, or a pseudo-alkaline earth metal, and L is an acetylide (C≡CA, where A is a silyl group having 0 to 6 carbon atoms or an alkyl group having 1 to 10 carbon atoms) or a dialkylamide having 1 to 10 carbon atoms, the reaction being carried out to form an RSnL having a Sn-C bond. ３ wherein R is a hydrocarbyl ligand having 1 to 20 carbon atoms and one or more silicon and / or germanium heteroatoms. The method includes:

24. The RSnL ３ is reacted with alcohol HOR' to give RSn(OR') ３ 24. The method of claim 23, further comprising forming:

25. RX to MSnL ３ React with RSnL ３ 25. The method of claim 23 or 24, wherein forming comprises reacting at a temperature of about -78.5°C to about 10°C.

26. M=K, and the RX and the KSnL ３ The method of claim 23 or 24, wherein is provided in a molar ratio of about 1:1 to about 3:

1.

27. 25. The method of claim 23 or 24, wherein the R moiety is ethyltrimethylsilyl.

28. MSnL ３ is KSn(TMSA) ３ The method according to claim 23 or 24, wherein

29. The RSnL ３ Before forming the MSnL ３ wherein the preparing further comprises preparing an alkyl lithium having the formula R″Li and an alkyl lithium having the formula SnX′ ２ with a reactant having the formula KZ and a reactant having the formula HL to form the KSnL ３ 25. The method of claim 23 or 24, comprising forming:

30. 30. The method of claim 29, wherein the alkyllithium and the alkyl / silylacetylene are provided in stoichiometric amounts or the alkylacetylene is provided in about 1 mol % to about 50 mol % excess over the stoichiometric amount.

31. The tin dihalide is SnCl ２ and the reactant having the formula KZ comprises potassium t-butoxide, and the reaction is carried out in an anhydrous organic solvent at a temperature below 0° C.

32. 1. A method for patterning an organometallic compound, comprising the steps of: forming a coating on a substrate, the coating comprising RSnL ３ where R is a hydrocarbyl group having 1 to 20 carbon atoms and one or more silicon or germanium heteroatoms, and L is a hydrolyzable ligand; exposing the coating to radiation to form a latent image; developing the image to form a patterned coating having nanoscale features in accordance with the latent image; The method includes:

33. 33. The method of claim 32, wherein the hydrolyzable ligand comprises an alkoxide, a dialkylamide, or an alkyl / silyl acetylide.

34. 34. The method of claim 32 or 33, wherein the substrate comprises silicon.

35. 34. The method of claim 32 or 33, wherein the depositing comprises vapor deposition, spin coating, spray coating or dip coating.

36. The method of claim 32 or 33, wherein the coating has an average thickness of 0.5 nm to 100 nm.

37. 34. The method of claim 32 or 33, wherein the coating has a root-mean-square surface roughness of less than 0.5 nm as measured by atomic force microscopy.

38. 34. The method of claim 32 or 33, further comprising heating the coating to a temperature of about 30° C. to 300° C. for a period of about 10 seconds to about 10 minutes prior to irradiating the coating.

39. The heating is carried out under a controlled partial pressure of a gas, the gas being H ２ O, CO ２ , CO, H ２ , N ２ , H ２ 39. The method of claim 38, comprising S, HCl, an inert gas, or a combination thereof.

40. The irradiating is about 1 mJ / cm ２ ~Approx. 200mJ / cm ２ or about 2 mC / cm at 30 kV. ２ 34. The method of claim 32 or 33, comprising an electron beam at a dose equal to or less than 100 nm.

41. 34. The method of claim 32 or 33, further comprising heating the coating to a temperature of from 45° C. to about 300° C. for a period of at least about 0.1 minutes to about 30 minutes after irradiating the coating.

42. 34. The method of claim 32 or 33, wherein the developing comprises an organic solvent or the developing comprises a solventless process.

Images