Organotin photoresist compositions with enhanced stability - Patents.com

Abstract

Organotin precursor solutions are described that include an organic solvent, optional additives, and an organotin composition represented by one or more organotin compounds of the formula RSnL3, where each R is independently a hydrocarbyl ligand having 1 to 31 carbon atoms and each L is independently a hydrolyzable ligand, where the total concentration of Sn is from about 0.001 M to about 0.5 M. The solvent can include a linear alcohol having 1 to 6 carbon atoms, and the organotin precursor solution can have an initial water content of from about 100 ppm to about 10,000 ppm, where the organotin precursor solution has a reduced rate of water evolution compared to an equivalent organotin precursor solution formed using 4-methyl-2-pentanol. The organic precursor solution can be prepared by selecting an appropriate stabilizing compound, which can be a linear short chain alcohol, and an appropriate additive.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to co-pending U.S. Provisional Patent Application No. 63 / 276,749, filed November 8, 2021, to Jiang et al., entitled "Additive-Enhanced Organotin Photoresist Compositions," which is incorporated herein by reference.

[0002] The present invention relates to organotin precursor solutions suitable for forming radiation patternable materials for lithographic patterning, which solutions contain stabilizing compounds, co-solvents and / or additives to reduce ligand hydrolysis and stabilize the solutions. [Background technology]

[0003] Semiconductor manufacturing processes typically involve the repeated processing and patterning of many different layers of materials to produce devices. The initial patterning of each layer and material is enabled through the use of photolithography, where an initial pattern is formed using a light-sensitive material called photoresist, which is then transferred to the underlying substrate. This process is typically repeated multiple times until the desired device structure is achieved. Photoresist is therefore a key material used in the manufacture of semiconductor devices. [Brief description of the drawings]

[0004] [Figure 1] A series of 119Sn spectra of organotin solutions prepared using 4-methyl-2-pentanol solvent and various proportions of n-propanol co-solvent, each solvent composition normalized to 300 ppm water. [Diagram 2] 2 is a series of 119 spectra of the organotin solutions of FIG. 1 after storage at room temperature for 30 days. [Diagram 3]FIG. 1 is a plot of measured water content versus days after formulation for a set of organotin solutions prepared with 4-methyl-2-pentanol solvent and various percentages of n-propanol co-solvent, each solvent composition normalized to 300 ppm water. [Figure 4] FIG. 1 is a plot of measured water content versus days after formulation for a set of organotin solutions prepared using 4-methyl-2-pentanediol solvent and various proportions of n-propanol co-solvent, with each solvent composition normalized to 1000 ppm water. [Diagram 5] 1 is a plot of measured water content versus days after formulation for a set of organotin solutions prepared with 4-methyl-2-pentanol solvent standardized to 1000 ppm water and various concentrations of ethylene glycol additive. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Additives and / or solvent compositions, e.g., solvents including primary alcohols, optionally with another solvent component, have been discovered that stabilize solutions of organotin compounds to improve shelf life and facilitate consistent use as radiation patterning compositions. The properties of organotin precursor solutions can be evaluated in terms of the change in water content of the solution over time relative to the initial water content, since the water content can indicate the degree of hydrolysis that occurs as a result of trace moisture. Organotin compositions have been demonstrated to function as high resolution patterning compositions, and further improvements in the stability of the patterning compositions promise to further extend the useful range of highly productive compositions. Formation of layers of photopatterning compositions can be formed using a solution coating process that uses an organotin photoresist precursor solution. Both appropriately selected solvents and additives have been found to be useful for improving the shelf life of the desired compositions and for extending the range of practical precursor compositions that can be utilized for photopatterning with sufficient stability. Solvent blends can be particularly desirable to bring out the stabilizing function while having the flexibility to set other solution parameters such as viscosity. As used herein, the co-solvent in the solvent blend is generally a liquid that provides desirable ligands to inhibit cluster formation of the solvated organotin (IV) compound. Unbranched primary alcohols (linear alcohols) have been found to serve this purpose as solvents or co-solvents. The additives are generally added in smaller amounts, e.g., in the same order of moles as the tin ions provided by the organotin precursor, although the additives may be in significantly higher multiples on a per mole basis. The additives may provide alternative ligands that compete with the solvent ligands to stabilize the organotin compound in solution. Proposed mechanisms for the stabilization process are discussed below, but do not wish to be limited by theory. Regardless of the mechanism, the stabilizing compounds, (co)solvents and / or additives may also affect the composition of the processed radiation-sensitive coating, potentially increasing the contrast for patterning between irradiated and non-irradiated portions of the coating, as well as reducing defects.The molecules of the stabilizing compound are believed to coordinate to the tin as ligands. Specifically, the co-solvent and / or additive molecules can coordinate around the tin(IV) ion as ligands to stabilize the compound against hydrolysis. In general, processing and development can be carried out without modification.

[0006] The function of the (co)solvent or additive is believed to be essentially equivalent, but the mechanism is generally not specifically elucidated. The concentration is generally believed to only affect the ligand equilibrium and generally does not change the basic mechanism. +4 ) is believed to be capable of accepting up to six ligands. With one carbon-tin bond and three negatively charged ligands, the basic structure suggests the ability to accept two additional ligands. The solvent may be able to provide some ligand strength to accommodate one or two additional ligands. As described herein, co-solvents to inhibit hydration by trace moisture include linear alcohols, n-HOR (where R = (CH2) n CH3, n=0-5). In the precursor solutions described herein, the linear alcohol can delay or inhibit the binding of water ligands to Sn, which can advantageously delay the hydrolysis of alkoxy ligands to form hydroxide ligands. The linear alcohol can be blended with another solvent, such as a secondary or tertiary alcohol, to provide the desired rheology for processing the solution into a patterning composition on a substrate. In the examples, 4-methyl-2-pentanol (also known as methyl isobutyl carbinol or MIBC) blended with n-propanol is used. 4-methyl-2-pentanol is the solvent of choice in Applicant's organotin product development because of its convenient characteristics for semiconductor processing. For this reason, 4-methyl-2-pentanol is used as a reference solvent for evaluating stabilization-related properties.

[0007] Additives can provide alternative ligands to complete the tin ligand shell and perhaps replace solvent ligands with stronger ligand bond strength. Suitable additives include carboxylic acids and their halogenated derivatives, which have been shown to provide some degree of stabilization. In some embodiments, it may be desirable to add polydentate ligand additives with multiple functional groups. Each polydentate ligand can form multiple bonds with the tin to provide additional stability of the ligand. Bidentate ligands include, for example, diols, triols, diketones, amino alcohols, and amides (e.g., dimethylurea). The results of the examples below demonstrate that these additives can increase the stability of the solution by inhibiting hydrolysis due to trace moisture. Since solvated tin moieties are prone to complex formation, having stronger ligand bonds can limit the likelihood of hydrolysis and the corresponding complex formation and precipitation from complex aggregation.

[0008] However, organotin compositions have a propensity to hydrolyze and condense in solution, which can result in the formation of unwanted particulates in solution and related coating defects over time. For example, hydrolysis of nominally monomeric (solvated) monoorganotin precursors with tetracoordinated Sn atoms generally results in the formation of oxo / hydroxo clusters with pentacoordinated and hexacoordinated Sn atoms, such as those of the formula [(RSn) 12 O 14(OH)6](OH)2. Such clusters can continue to undergo hydrolysis and condensation processes to oligomerize and form large amounts of precipitates and solids. It is therefore desirable to impede the hydrolysis and condensation processes in organotin photoresist solutions. It has been discovered that the hydrolysis of organotin compositions in organic solvents can be impeded in the presence of suitable stabilizing compounds. Reaction with water in solution is generally undesirable as it can cause polymerization of the organotin species to form larger clusters, which can aggregate and / or precipitate in solution, causing solid formation in the wafer track or defects on the wafer or in the resist coating during use of the precursor composition. Particles formed in solution that do not form precipitates (such as suspended particles) can still be transferred to subsequent coatings, which in turn can result in coating and / or patterning defects.

[0009] Without wishing to be limited by theory, it is believed that suitable stabilizing compounds can coordinate and / or complex with Sn atoms to form hydrolysis-resistant species, but the mechanism by which this occurs may vary. Furthermore, it is believed that bidentate additives can inhibit hydrolysis by forming bonds between Sn and two or more reactive groups of the additive molecule (e.g., two -OH groups of a diol), thereby providing both energetic and entropic advantages to hinder hydrolysis. In general, stabilizing compounds can substitute for hydrolyzable ligands and / or form additional ligands to provide penta- or hexa-coordinated Sn.

[0010] The reactivity and propensity of the RSn moiety to form higher coordination numbers can also generally be influenced by the identity of the R ligand. For example, larger and bulkier R groups can sterically hinder bulky alcohols and other species from reacting, complexing, and / or coordinating with the Sn atom. As shown in the examples below, organotin precursors solvated by bulky secondary alcohols such as 4-methyl-2-pentanol generally contain tetracoordinated Sn atoms that are susceptible to reaction and displacement with small molecule reactants such as water, methanol, or n-propanol. However, when molecules other than water cluster to form species with hexacoordinated Sn environments, the resulting species remains soluble. Without wishing to be limited by theory, it is believed that coordination and / or complexation of the RSn moiety with suitable non-water molecules, e.g., those that can satisfy the coordination number of Sn, hinders the propensity of the organotin species to condense and oligomerize. Interfering with the propensity of organotin species to condense can improve the homogeneity of photoresist solutions and resulting coatings.Additives and solvents that can coordinate and / or complex with monomeric organotin precursors to form soluble products with penta- or hexa-coordinate Sn environments would therefore be desirable.

[0011] The overall formulation may generally include a wide range of potential species equilibria that may be differentiated by the identity of the ligands, the arrangement of the ligands, the possibility of some bridging of the ligands, and temporary or non-temporary clustering. In solution, the species at any particular time depend on the balance of various equilibria of the particular species, which may include interconnections resulting in extremely complex relationships. In general, these complexities are not important except with respect to the functionality of the precursor solution for its intended purpose. Thus, the main issue is to keep these moieties in solution, since precipitation of the organotin moieties may make the composition unworkable. As the results show below, there may be measurable signs of the precursor solution changing over time. In particular, some degree of gradual hydration may occur, even if inhibited. Some systems are stable for very long periods, while others may precipitate in shorter periods. The goal of selecting the appropriate solvent and additives is to extend the period of instability far enough into the future to exceed a reasonable commercial shelf life.

[0012] Water can result in hydration that destabilizes the precursor solution, and while it is possible to reduce water to low levels, it is not practical to reduce it to a substantially zero amount. Trace amounts of water can be introduced from a variety of potential sources, so an effective way to address the water issue is to control the water to low levels and to make the composition robust to low, non-zero levels of water. It is an object of the present invention to support this robustness to provide a desired shelf life under reasonable commercial use. Applicants have previously considered adjusting the water level for consistent results. This water adjustment is described 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" (hereinafter the '876 patent), which is incorporated herein by reference. In general, it may be desirable to adjust (i.e., standardize) the water content of the solvent used to form the organotin precursor solution enriched with the stabilizing compounds described herein. As described further below, the teachings of the '876 patent can be combined with the use of additives and co-solvents for stability as described herein.

[0013] It is desirable to improve photoresist performance to reduce manufacturing costs and improve yields in semiconductor device manufacturing. Organometallic materials, particularly those based on organotin compositions, have been shown to be high-performance photoresists that enable patterning of high-resolution and high-fidelity patterns. 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" (hereinafter the '684 patent), 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 to Meyers et al., entitled "Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning," all of which are incorporated herein by reference. Typically, 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 formation of an extended dense network, thus maintaining 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, results in scission of the Sn-C bonds, allowing further densification of the exposed regions, thereby increasing the solubility contrast between exposed and unexposed regions. In this way, patterning of the coating can be achieved after development.

[0014] Although a variety of organotin compositions can be effective radiation patterning materials, compounds having a single carbon-tin bond have been found to provide desirable processing for patterning in commercial situations, and the following discussion focuses on these mono-organotin compositions. Thus, the organotin precursor compositions can include a group of compositions (RSnL3) that can be hydrolyzed under appropriate conditions with water or other suitable reagents to form mono-hydrocarbyltin oxo-hydroxo patterning compositions, which, when fully hydrolyzed, have the formula RSnO (1.5-(x / 2)) (OH) x(where 0 < x ≦ 3). Generally, as further described below, R is a hydrocarbyl ligand and L is a hydrolyzable ligand. It may be convenient to perform hydrolysis to form an oxo-hydroxy composition in situ, for example during deposition and / or after the first coating formation. In particular, triamides (L = amide) and trialkoxides (L = alkoxide) can be used under hydrolysis conditions to form radiation-sensitive coatings for patterning, and current commercial products are based on trihydrocarbyloxides such as trialkoxides. The terminology follows the convention of hydrolyzable ligands, but it should be noted that these can include various substituted organic substituents with potential unsaturated bonds or heteroatom substitutions. Various precursor compounds with hydrolyzable ligands generally carry the R ligand to tin through a pre-irradiation process and are synthesized in this regard. Hydrolyzable ligands include, for example, alkoxides (hydrocarbyloxides), acetylides or amide moieties. These compositions can be synthesized using a wide range of R ligands. For example, as described 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. In some embodiments, as described in 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 organotin precursor compound can be purified after synthesis by appropriate techniques such as fractional distillation.

[0015] R forms a carbon-tin bond, where the carbon bonded to tin is sp 3 or sp2 R is a heteroatom that is neither carbon nor hydrogen. As stated above, for convenience and consistency in the art, R can be interchangeably referred to as an alkyl ligand, an organic ligand, or a hydrocarbyl ligand. Based on the nature of the ligand, sp hybridized carbons that bond to tin form acetylide ligands, which are classified as L ligands, but not R hydrocarbyl ligands. In some embodiments, alkyl ligands may be desirable for some patterning compositions, where the compound is generally R 1 R 2 R 3 CSnO (2-(z / 2)-(x / 2)) (OH) x (In the formula, R 1 , R 2 and R 3 are independently hydrogen or an alkyl group having 1 to 10 carbon atoms. Similarly, this representation of an alkyl ligand R can generally be expressed as R 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, or amide moiety. In some embodiments, R 1 and R 2 can form a cyclic alkyl moiety, R 3 may also be linked to other groups on the cyclic moiety. Suitable branched alkyl ligands are, for example, isopropyl (R 1 and R 2 is methyl, R 3 is hydrogen), tert-butyl (R 1 , R 2 and R 3 is methyl), tert-amyl (R 1 and R 2 is methyl, R 3 is -CH2CH3), sec-butyl (R 1 is methyl, R 2 is -CH2CH3, R 3 is hydrogen), neopentyl (R 1 and R 2is hydrogen, and R 3 is -C(CH3)3), cyclohexyl, cyclopentyl, cyclobutyl, and cyclopropyl. Examples of suitable cyclic groups include, for example, 1-adamantyl (-C(CH2)3(CH)3(CH2)3 or tricyclo(3.3.1.13,7)decane attached to the metal at a tertiary carbon) and 2-adamantyl (-CH(CH)2(CH2)4(CH)2(CH2) or tricyclo(3.3.1.13,7)decane attached to the metal at a secondary carbon). In other embodiments, the hydrocarbyl group may include an aryl or alkenyl group, such as benzyl or allyl, or an alkynyl group. In other embodiments, the hydrocarbyl ligand R may include any group consisting of only 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 groups (i-Pr((CH3)2CH-), t-Bu((CH3)3C-), Me(CH3-), n-Bu(CH3CH2CH2CH2-)), cycloalkyl groups (cyclopropyl, cyclobutyl, cyclopentyl), olefinic groups (alkenyl, aryl, allyl), or alkynyl groups, or combinations thereof. In further embodiments, suitable R groups can include hydrocarbyl groups substituted with heteroatom functional groups including cyano, thio, silyl (and germanium analogs), ether, keto, ester, or halogenated groups, or combinations thereof.

[0016] In some embodiments, the organotin composition comprises a mixture of organotin compounds having different R groups and correspondingly the same and / or different L groups attached thereto. In some embodiments, the organotin composition has R ligands comprising a blend of linear alkyl ligands and non-linear alkyl ligands. In some embodiments, the blend of linear alkyl ligands and non-linear alkyl ligands comprises branched alkyl groups, cycloalkyl groups, or aryl groups. In some embodiments, the organotin composition is a mixture of separate organotin compounds having methyl and t-butyl ligands, respectively. In some embodiments, the precursor composition comprises a blend of organotin compounds having the same and / or different L groups. In some embodiments, the organotin composition comprises separate organotin compounds having L ligands comprising dialkylamides, alkylsilylamides, alkyloxides, alkylacetylides, or combinations thereof. In other embodiments, the organotin composition comprises separate organotin compounds having L ligands comprising methoxide, ethoxide, propoxide, isopropoxide, butoxide, isobutoxide, tert-butoxide, tert-amyl oxide, dimethylamide, diethylamide, diisopropylamide, trimethylsilylamide, or combinations thereof. In embodiments in which a blend of different organotin compounds is used, any one of the separate organotin compounds can comprise from about 1 mol % to about 99 mol % of the total organotin moles in some embodiments, from about 5 mol % to about 95 mol % of the total organotin moles in other embodiments, from about 10 mol % to about 90 mol % of the total organotin moles in other embodiments, and from about 15 mol % to about 85 mol % of the total organotin moles in further embodiments. In the examples below, an organotin precursor solution is demonstrated that comprises a mixture of two separate alkyltin tri-tert-amyl alkoxide compounds. As is conventional in the art, hydrocarbyl groups may contain unsaturation, aryl groups, heteroatoms, and the like, but the groups are sometimes referred to as alkyl groups.

[0017] In some embodiments, the precursor composition comprises a mixture of R-Sn moieties having hydrocarbyl ligands and SnL'4 compounds, i.e., tin compounds having no alkyl ligands directly bonded to the metal and L' corresponding to a hydrolyzable ligand. In some embodiments, L' can be the same as L, as described above. The additives and / or solvent blends described herein can also coordinate to the tin(IV) ions of the SnL'4 compounds to stabilize the SnL'4 compounds against hydrolysis. Generally, these mixtures comprise at least about 0.5 mole percent of the SnL'4 component, in some embodiments at least about 1 mole percent, in some embodiments at least about 10 mole percent, and in further embodiments at least about 25 mole percent of the SnL'4 component. In other embodiments, the precursor composition comprises one or more organotin compounds represented by the formula RSnL3 and up to about 30 mole percent, up to about 20 mole percent, up to about 10 mole percent, or up to about 1 mole percent of SnL'4 relative to the total Sn. A person of ordinary skill in the art will recognize that additional ranges of mixture components within the explicit ranges above are contemplated and are within the scope of the present disclosure. In some embodiments, the components of the precursor composition can be combined in solution, e.g., prior to the formation of a coating, and do not have to be formed separately as a solid blend. In other embodiments, the components of the precursor composition can be mixed as solids prior to dissolution to form a precursor solution. In the examples below, an organotin precursor solution is demonstrated that includes a mixture of an alkyltin trialkoxide and a tin tetraalkoxide.

[0018] Most of the organotin precursor compounds of interest are liquids at room temperature, although soluble solids can be processed as well. Upon deposition and removal of the solvent, as described below, the precursor can be hydrolyzed to a dry solid material. The organotin precursor is dissolved in a liquid to form a precursor solution. Generally, the solvent interacts with the solute to keep it in solution, and in the case of ionic metal species, complex interactions are generally available. Tin+4(Sn +4Sn(IV) may be hexadentate for ligand formation. Purified (pure) compounds generally have tetracoordinations, but potentially some ligands can be crosslinked. Without replacing any of the ligands, the precursor compound may have two free ligand binding sites that can be bound to the solvent. If a suitable co-solvent is present, the co-solvent, e.g., linear alcohols, may compete for these ligand binding sites with alternative co-solvents that may not bind as effectively to these ligand sites. Linear alcohols are generally effective at competing with other co-solvents, including water, to provide solution stabilization.

[0019] Also, if bridging ligands are available, the tin moieties can form clusters in solution, and thus complexation can be another complication with respect to solution stability. Some stable trimer clusters are described in U.S. Pat. No. 11,098,070 to Cardineau et al., entitled "Organotin Clusters, Solutions of Organotin Clusters, and Application to High Resolution Patterning," and stable dodecamer clusters are described in U.S. Pat. No. 11,392,028 to Cardineau et al., entitled "Tin Dodecamers and Radiation Patternable Coatings with Strong EUV Absorption," both of which are incorporated herein by reference. These clusters can have oxygen atoms, hydroxide ions, and / or carboxylate ions as bridging ligands. The identification of these and other known stable tin clusters points to the possibility of forming temporary clusters in the precursor solution that can affect solution stability. For example, aggregation of clusters can result in the nucleation of microparticles.

[0020] In general, organometallic solutions are very complex and may involve various equilibria. Some known chemical phenomena can be used to deduce the observed properties. The limited ability to probe the details of the solution structure implies that the depiction is necessarily incomplete. This incompleteness does not impair the ability or success to control the process to a significant degree, achieved using the additives and / or co-solvents described herein to stabilize the precursor solution.

[0021] Although undesirable condensation of tin compositions in solution is generally associated with water, water may not be the only cause of instability. Water may be designed to be kept at low levels during processing, but it may be extremely difficult or impossible to completely remove water due to absorption from the surrounding environment, which may include air, equipment, contaminants in the reactants, etc. For consistency in commercial processing, it is advantageous to design a system that is stable within achievable limits at low moisture levels. The presence of some water promotes the tendency to hydrolyze ligands to introduce hydroxide or oxygen ligands that can bridge between tin atoms. The presence of potentially bridging ligands may promote cluster formation and potential condensation due to cluster aggregation. Due to the complex equilibrium in these solutions, as described above, the amount of water present may tend to shift the equilibrium. The additives and / or co-solvents described herein tend to shift the equilibrium from hydrolysis and stabilize the solution. A measure of stability is found in terms of resistance to reaction with water, which can be estimated by the amount of measurable free water remaining in the solution, but due to the complexity of the equilibrium, the details of the species present are not accounted for. The reduction or cessation of measurable free water consumption in solution can be achieved by the use of appropriate solvents and / or additives, and the change in water consumption over time can be evaluated against a 4-methyl-2-pentanol solvent standard with the same composition and concentration of initial tin species.

[0022] As noted above, reaction of monomeric RSnL3 species with water, i.e., hydrolysis, generally leads to oligomeric organotin oxo-hydroxo clusters over time. Thus, while organotin oxo-hydroxo species can be successfully processed in solution to form radiation patterning materials as described in the '684 patent, many oxo-hydroxo organotin clusters have low solubility, and therefore uncontrolled reaction of organotin precursors with water in solution can lead to particulate formation and precipitation / aggregation of insoluble species. Water is generally present in most solvents at some concentration unless great care is taken. Water absorption by the solvent can occur under ambient conditions during manufacturing, filtration and other processing, as well as upon exposure to air during normal use. Water from the ambient air can also permeate container walls, leading to an increase in the water content of the solvent. When installed in a coating apparatus such as a wafer track, the organotin photoresist solution is generally piped through various lines, tubes, tanks, pumps, and other equipment of the materials of construction that may be susceptible to water penetration. It is therefore desirable to formulate organotin photoresist solutions that are resistant or resistant to adverse hydrolysis in solution.

[0023] In order to achieve consistent processing results, it has been found to be beneficial to control the water content of the solvent used in the process, even if the water content is at a relatively low level. In some embodiments, it may be desirable for the organotin resist solution to be water-normalized, e.g., to contain a specific amount of water as described in the above-referenced '876 patent. Common organotin precursors, such as organotin trialkoxides and triamides, readily hydrolyze and react with different amounts of water to yield variable species distributions. Thus, adding a specific concentration of water to the organotin resist solution composition can improve batch-to-batch reproducibility by promoting the formation of a similar distribution of hydrolyzed and non-hydrolyzed species. However, it is desirable to enable and / or enhance the solution stability of such water-normalized organotin resist solutions with respect to precipitation, aggregation, and / or particulate formation. An appropriate stabilizing compound can effectively prevent continued hydrolysis and / or condensation from occurring in the water-normalized organotin resist solution. In the following examples, the addition of appropriate amounts of additives or co-solvents demonstrates improved shelf life of the organotin resist solution and resistance to precipitation at high moisture levels.

[0024] In principle, various methods can be used to assess the water content of a sample, but Karl Fischer titration is an effective and practical approach. Karl Fischer (KF) titrators are commercially available for rapid and automated assessment. KF titrators are commonly available from commercial suppliers such as Mettler-Toledo LLC (OH, USA), Metrohm AG (Switzerland), and CSC Scientific Company (VA, USA). The assessment of free water in a sample can be useful to assess the effectiveness of a given stabilizing compound by comparing the concentration of free water in a composition fortified with the stabilizing compound and a non-stabilized compound fortified composition having a similar organotin concentration. Without wishing to be limited by theory, it is generally believed that for organotin solution compositions containing a suitable stabilizing compound, there is generally more free water in the corresponding stabilized compound fortified composition compared to the non-stabilized compound fortified composition. Since water is consumed during hydrolysis, for a given organotin precursor, a stabilized compound fortified organotin solution with more free water means that less hydrolysis has occurred compared to the non-stabilized compound fortified organotin solution. The concentration of free water in a sample is also referred to as the measured water content. The amount of water consumed during hydrolysis can be calculated as the initial water content minus the measured water content.

[0025] While it is generally desirable to prevent uncontrolled hydrolysis of organotin compositions in solution, it is also generally desirable to allow the organotin compositions to hydrolyze and condense during deposition and / or coating processing. For example, the formation of organotin oxide / hydroxide coatings generally involves the hydrolysis of hydrolyzable organotin compositions, such as RSn(OR)3, RSn(NR2)3, and / or related organotin clusters, during spin-coating and / or deposition processes. During spin-coating, the solvent rapidly evaporates from the substrate and the organotin compositions rapidly hydrolyze to provide an organotin oxo / hydroxo network. Thus, stabilizing compounds that prevent hydrolysis are desirable to allow sufficient hydrolysis and condensation of the organotin precursors to achieve an organotin oxo / hydroxo network. This achievement of solution stability and processability requires a balance of ligand formation and strength to allow hydrolysis at the desired stage without excessive hydrolysis prior to use.

[0026] The rapid deposition process can result in various species trapped and / or entrapped in the organotin oxo / hydroxo network, and undesirable species such as particulates can be entrapped or embedded in the organotin oxo / hydroxo network. The entrapment of particulates can lead to inhomogeneities in the coating and can manifest as coating defects. Such coating defects can affect subsequent processing of the substrate by transferring the defects to additional layers and further propagating to the semiconductor manufacturing process. The inhomogeneities in the coating can also lead to patterning defects. Inhomogeneities such as particulates and other impurities can interfere with pattern formation during exposure to patterned radiation, resulting in poor image conversion. Nanoscale patterning, i.e., patterning of features on the scale of tens of nanometers, requires feature resolution on a similar scale, which may otherwise be disrupted by the presence of smaller inhomogeneities. For example, undesirable particulates can result in various deleterious behaviors such as significantly increased feature roughness, increased microbridging, delamination and / or line wobble, and missing portions of the desired pattern (e.g., missing contacts).

[0027] Filtration can be effective in removing inhomogeneities such as particles from organotin resist solutions, and such methods are 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," incorporated herein by reference. However, through mechanisms such as those described above and reactions with water, formation of further hydrolysis / condensation products and particles may occur after the initial filtration. Thus, prevention of further particle formation is desirable, and organotin photoresist solutions can include suitable stabilizing compounds to impede uncontrolled hydrolysis during aging and handling, as described herein.

[0028] In some embodiments, suitable stabilizing compounds can include molecules that drive the complete displacement of ligands on the organotin precursor species according to the following reaction: RSnL3+3HA → RSnA3+3HL

[0029] In other embodiments, suitable stabilizing compounds can include molecules that partially replace ligands on the organotin precursor species according to the following reaction: RSnL3+nHA → RSnL 3-n (A) n +nHL (0≦n<3)

[0030] Some stabilizing compounds can neutralize the ligand by transferring a hydrogen atom to the L - The electrostatic charge can displace the ligand. - It is likely that the ligands remain primarily in close proximity to the tin cation, but it is suggested that they may be appropriately solvated. The following possibilities are described: RSnL3+nA → RSnL 3-n (A)n +nL - (0≦n<3)

[0031] In a further embodiment, a suitable stabilizing compound can form a ligand to Sn at the fifth and possibly sixth ligand binding positions without displacing the initial ligand: RSnL3+nA → RSnL3(A) n (0 <n≦2)

[0032] Additionally, suitable stabilizing compounds are capable of forming ligands of a blend of these functional groups as determined by the amount of additive added and the equilibrium according to the following reaction: RSnL3+nHA → RSnL 3-m (A) n +mHL(0 <n≦5、0≦m≦3、n≧m)

[0033] In these formulas, n and m are considered to be positive whole numbers rather than integers, even though the species formed for any particular molecule may represent integers. As noted above, in solution, complex equilibria give rise to mixtures of various species.

[0034] Although linear alcohols can be considered HA additives, they are identified separately herein as cosolvents since they are generally present in higher concentrations. Suitable additives include carboxylic acids, polyols, amides, aminoalcohols, diketones, mixtures thereof, and fluorinated derivatives thereof.

[0035] Precursor solution The precursor solution generally comprises one or more solvents, an organotin composition, and optional additives. To avoid ambiguity, the concentration of the tin component is referred to the tin ion, regardless of the bonding structure. The solvent may be a solvent blend with a linear alcohol co-solvent. Generally, for the stabilization solutions described herein, the precursor solution comprises a linear alcohol co-solvent, an additive, or a combination thereof.

[0036] With respect to organotin precursor solutions, reference to composition generally refers to the species that are combined to form the solution. As asserted above, the potential rearrangements resulting from blending generally involve an interrelated equilibrium of complexes that may result in a relatively static steady-state mixture of solvated moieties, or that may change slowly and potentially eventually become destabilized. Thus, the precise characterization of the species in solution is generally not known.

[0037] The concentration of the precursor solution can be conveniently specified based on the molar concentration of tin ions, and the concentration of any other metal can be specified accordingly by the mole fraction value of that metal relative to tin. Generally, the precursor solution contains about 0.0005M to about 1M tin cation, in further embodiments, about 0.001M to about 0.8M, about 0.001M to about 0.5M, about 0.01M to about 0.5M, about 0.025M to about 0.5M tin cation, including ranges and subranges with replaced upper and lower limits. Highly purified precursor solutions with very low metal contaminants are described in 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. A person of ordinary skill in the art will recognize that additional ranges of tin / metal cation concentrations within the explicit ranges above are contemplated and are within the present disclosure.

[0038] Stability can be evaluated by the appearance of the precursor solution. In general, it is desirable for an organotin composition to have sufficient stability over an extended period of time, e.g., in terms of shelf life and performance consistency. As described herein, the stability of the precursor solution can be effectively enhanced by the use of co-solvents and / or additives. Other aspects of the composition, such as the selection of alkyl ligands and / or control of the water content of the solution, can also affect stability. With the establishment of solution stability, a stabilized organotin precursor solution is expected to provide reliable reproducibility of coating processing and patterning results. As described in the examples below, mixing either a linear alcohol or an additive with a solution containing a monoalkyltin trialkoxide has been shown to reduce the impact of aging of the organotin resist precursor solution on the patterning performance of the photoresist. Another way to evaluate cluster formation is to examine the concentration of free water over time. If hydrolysis is slowed down or inhibited, water uptake may be slowed down or inhibited accordingly. The results in the examples below are consistent with this. Thus, the change in free water over time from the initial value at the time of mixing can provide information on cluster formation. This may be a reference to current commercial resists that use 4-methyl-2-pentanol solvent and no stabilizing compounds.

[0039] Stability can also be evaluated in terms of the time until visible solids are observed precipitating from the solution. Applicants have developed organotin compositions formulated to be stable for significant periods of time, in some cases exceeding six months or even longer than one year. The additional stabilization approaches described herein allow for the stabilization of organotin compositions with a broader range of ligands, thus improving patterning with a broader range of available ligands for patterning compositions. Using the stabilization compounds described herein can increase the average stability of the stabilized precursor solution in terms of the observation of visible solids. In some embodiments, the stabilized organotin precursor solution can have an average stability of at least one week, and in other embodiments at least one month, when stored in a sealed container, than a comparable organotin precursor solution without the stabilization compound. One of ordinary skill in the art will recognize that additional ranges of stability enhancements within the above explicit ranges are contemplated and are within the scope of the present disclosure.

[0040] The solvent can be selected to support a stable dispersion of the organotin compound. In some embodiments, a solvent including a short chain linear alcohol can be used as a stabilizing compound. The linear alcohol, with or without a stabilizing additive, can be used as the sole solvent if other solution properties are appropriate, or can be used as a co-solvent blended with other solvent components. In addition to stably dispersing the organotin compound, the precursor solution must provide the desired properties for processing the radiation patternable composition. Important properties include, for example, solubility parameter, evaporation, flash point, toxicity, and viscosity. For certain applications, it is desirable for the organic solvent to have a flash point of about 10° C. or more, in further embodiments about 20° C. or more, and in further embodiments about 25° C. or more. Also, for drying purposes, it may be desirable for the solvent to have a boiling point of about 250° C. or less, in further embodiments about 225° C. or less, and in other embodiments about 200° C. or less. Suitable solvents can 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-propanol, t-amyl alcohol, 1-butanol, 1-propanol, ethanol, methanol, isopropyl alcohol), ketones (e.g., diethyl ketone), mixtures thereof, and the like. For clarity, any organic compounds included in the description of additives below are not considered solvents as that term is used herein. For purposes of spin coating and other processing, the precursor solution can have a viscosity of about 0.5 centipoise (cP) to about 50 cP, in further embodiments from about 1 cP to about 35 cP, and in other embodiments from about 1.5 cP to about 25 cP. One of ordinary skill in the art will recognize that additional ranges of flash points, boiling points and viscosities within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0041] Some precursor solutions contain unbranched primary alcohols (linear alcohols) with six or fewer carbon atoms (CH3(CH2) nIt is desirable to use a solvent blend with a co-solvent that is an alcohol, such as tin ion, ... The use of solvent blends provides one or more additional parameters for tailoring the overall solution properties, and the stabilizing effect of the linear alcohol is observed in such blends. One of ordinary skill in the art will recognize that additional ranges of unbranched primary alcohol compositions within the explicit ranges above are contemplated and are within the scope of the present disclosure.

[0042] In some embodiments, unbranched primary alcohols having 6 or fewer carbon atoms may be used in the solvent blend if their viscosity is undesirably low alone for certain applications such as spin coating, to provide a higher flash point, or for other potential practical reasons, but in some embodiments, it may be appropriate to use a linear alcohol alone. In some embodiments, both a linear (carbon number ≦6) alcohol and an additive may be included in the organotin precursor solution as a stabilizing compound. When the precursor solution has both one or more linear (carbon number ≦6) alcohols and an additive, another solvent may or may not be included.

[0043] Additives may be added to provide the desired degree of stability. Unlike co-solvents, the amount of additive is generally relatively low in molar terms, but the upper molar limit of the additive may be about as large as the lower molar limit of the unbranched primary alcohol. As opposed to a reference to the total amount of solvent, the amount of additive is generally referred to in terms of the tin concentration. Additives may be liquids or solids, and potentially dissolved gases. The effectiveness of a particular additive may depend on the properties of the organotin composition.

[0044] In some embodiments, suitable additives include, for example, diols, carboxylic acids, amides (e.g., alkyl ureas, including dimethyl urea), amino alcohols (e.g., (ROH) 3-n NH n , n=0-2, including ethanolamine, diethanolamine, and triethanolamine), diketones (e.g., 1,3-diketones including acetylacetone), formamide / alkylformamides (e.g., N,N-dimethylformamide), or triols (e.g., glycerol), mixtures thereof, fluorinated derivatives thereof, and the like. In general, suitable additives can be characterized by their volatility. For example, some additives are generally sufficiently volatile to evaporate and volatilize during deposition and not be significantly incorporated into the organotin oxo / hydroxo coating. Conversely, in some embodiments, an additive may not be sufficiently volatile and may be incorporated into the organotin oxo / hydroxo coating. In additional embodiments, additive A may form non-volatile and / or sufficiently non-hydrolyzable Sn-A bonds, for example, to be at least partially incorporated into the organotin oxo / hydroxo coating. The additives are generally added in small enough amounts so that any residue of the additive in the deposited radiation-sensitive composition does not significantly interfere with the formation of the oxo-hydroxo network after hydrolysis from available water during processing. In some embodiments, bifunctional additives can participate as bridging ligands, which can bridge between two or more Sn atoms.

[0045] Some suitable examples of diol additives include linear, branched, and cyclic diols having 1 to 6 carbons and their isomers, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-propanediol, 1,4,-butanediol, 1,2-cyclopentanediol, 1,3-cyclopentanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,2-cyclohexanol, 1,3-cyclohexanol, 1,4-cyclohexanol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, and mixtures thereof. Similarly, glycerol is a triol having the formula HOCH2CHOHCH2OH. In some embodiments, the diol or triol additive can include a molar ratio of diol to Sn of from about 0.05 to about 5; in further embodiments, the molar ratio can be from about 0.1 to about 2; and in further embodiments, the molar ratio can be from about 0.5 to about 1.

[0046] In some embodiments, suitable examples of carboxylic acids can include R'COOH, where R' is a linear, branched, or cyclic hydrocarbyl group having 1 to 6 carbon atoms, its fluorinated derivatives, and related isomers. Suitable examples of carboxylic acid additives can include, for example, formic acid, acetic acid, trifluoroacetic acid, propanoic acid, butyric acid, 2,2-dimethylpropanoic acid, isobutyric acid, pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, benzoic acid, cyclohexanoic acid, hexanoic acid, 2-methylpentanoic acid, 3-methylpetanoic acid, 4-methylpentanoic acid, and mixtures thereof. In some embodiments, the carboxylic acid additive can include a molar ratio of carboxylic acid molecules to Sn of about 0.005 to about 10, and in further embodiments, the molar ratio can be about 0.01 to about 6, about 0.01 to about 5, about 0.5 to about 3, about 0.1 to about 2, about 0.5 to about 1, about 1 to about 2, and in further embodiments, the molar ratio can be about 1 to about 3.

[0047] In some embodiments, the additive can include a suitable amino alcohol. In some embodiments, the suitable amino alcohol can include, for example, compounds having both hydroxyl (-OH) and amino (-NH2 groups) and having 1 to 6 carbon atoms. The amino alcohol can include linear, branched, or cyclic hydrocarbyl groups. Some examples of suitable amino alcohol additives can include, for example, ethanolamine, propanolamine (e.g., 1-amino-2-propanol, 3-amino-1-propanol, 2-amino-1-propanol), butanolamine (e.g., 2-amino-2-methyl-1-propanol, 1-amino-2-butanol, 2-amino-1-butanol, 3-amino-1-butanol, 4-amino-1-butanol), pentanolamine (e.g., 5-amino-1-pentanol, 4-amino-1-pentanol, 3-methyl-1-pentanol), diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, and mixtures thereof. In some embodiments, the molar ratio of amino alcohol to Sn can be from about 0.005 to about 10, and in further embodiments, the molar ratio can be from about 0.01 to about 6, from about 0.01 to about 5, from about 0.5 to about 3, from about 0.1 to about 2, from about 0.5 to about 1, from about 1 to about 2, and in further embodiments, the molar ratio can be from about 1 to about 3.

[0048] In some embodiments, the additive can include a dialkyl urea, such as dimethyl urea, diethyl urea, and the like, and the molar ratio of dialkyl urea to Sn can be from about 0.005 to about 10, and in further embodiments, the molar ratio can be from about 0.01 to about 6, from about 0.01 to about 5, from about 0.5 to about 3, from about 0.1 to about 2, from about 0.5 to about 1, from about 1 to about 2, and in further embodiments, the molar ratio can be from about 1 to about 3.

[0049] In some embodiments, the additive can include unsubstituted and fluoro-substituted 1,3-diketones, such as acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, and mixtures thereof, and the molar ratio of 1,3-diketone to Sn can be about 0.005 to about 10, and in further embodiments, the molar ratio can be about 0.01 to about 6, about 0.01 to about 5, about 0.5 to about 3, about 0.1 to about 2, about 0.5 to about 1, about 1 to about 2, and in further embodiments, the molar ratio can be about 1 to about 3.

[0050] In some embodiments, the additive-enhanced photoresist solution can include one or more additives as described above. In some embodiments, the additive-enhanced photoresist solution can include one or more additives as described above and a linear alcohol as described above. Those skilled in the art will recognize that ranges of additive amounts and molar ratios within the above explicit ranges are contemplated and are within the scope of the present disclosure. In general, the desired amount of additive can depend on the specific additive and its properties.

[0051] The stabilizing compounds can generally be introduced into the organotin photoresist solution by any suitable route. In some embodiments, the additives and / or co-solvents can be added in suitable amounts to the formulation solvent prior to the introduction of the organotin precursor. After the additives and / or co-solvents are added to the formulation solvent, the solvents can be appropriately mixed to ensure a homogenous solution. In other embodiments, the additives and / or co-solvents can be added to the organotin precursor prior to the introduction of the precursor into the formulation solvent. In other embodiments, the additives and / or co-solvents can be added to the mixture of the solvent and organotin precursor (i.e., the photoresist solution) and then appropriately mixed.

[0052] The involvement of water in processing has several potential aspects. To promote solution stability, water should generally be limited. As noted above, the water content can be standardized, and standardization processes are described in the above-cited '486 application. The precursor solution may or may not undergo water standardization by adjusting the water content of the solvent, although water standardization can be useful for stability control and consistency. Regardless of whether the water content of the solvent is standardized, the water content of the precursor solution can be monitored as a function of time to better understand possible chemical phenomena occurring in the precursor solution.

[0053] With respect to water normalization, the selected water content can be set to a value selected within a tolerance of about ±15 percent, in some embodiments ±10 percent, in further embodiments ±8%, and in other embodiments ±6%. As used herein, ppm is an abbreviation for μg / ml, which is ppm by weight relative to a solution density of 1 g / ml. The tolerance can be expressed as ±50 ppm, in further embodiments ±40 ppm, and in other embodiments ±25 ppm, with respect to the absolute water content, although the absolute tolerance can be larger from a practical standpoint when the selected water content is greater. With respect to the absolute value of the solvent water content, the solvent can be adjusted to have a water content of about 100 ppm to about 10,000 ppm, in further embodiments about 200 ppm to about 6000 ppm, in other embodiments about 300 ppm to about 5000 ppm by weight, in some embodiments about 300 ppm to about 4000 ppm, and in additional embodiments about 300 ppm to about 2500 ppm. The appropriate water content may depend somewhat on the tin concentration in the prepared precursor solution, such that a 0.5 M tin solution may be stable at a water content greater than a 0.05 M tin concentration in the prepared precursor solution. A person of ordinary skill in the art will recognize that additional ranges of water tolerance or water content within the values ​​set forth above are contemplated and are within the scope of the present disclosure.

[0054] As mentioned above, a suitable additive / co-solvent can generally prevent or retard water from reacting with the organotin species in solution. The reaction of the organotin precursor species with water generally consumes free water to produce organotin oxo / hydroxo species in solution, and thus measuring the difference in free water of a composition containing a stabilizing compound versus a composition without a stabilizing compound can inform the appropriate selection of a suitable stabilizing compound. Free water can generally be measured in an organic solvent by using Karl Fischer titration as described above. Generally, herein, the amount of free water in a solvent prior to combination with an organotin composition, as measured by Karl Fischer titration, can be referred to as the initial water content, and the amount of free water in the precursor solution can be referred to as the measured water content. The water content of an organotin solution immediately after preparation can also be referred to as the initial water content. In some embodiments, the initial water content of an organotin precursor solution can be equivalent to the initial water content of the solvent used to prepare the solution, within the measurement error. As described in the examples below, a suitable stabilizing compound can be selected based on the relative difference in the measured water content of the organotin precursor in a precursor solution containing the stabilizing compound versus an otherwise equivalent non-stabilized compound-containing precursor solution. Alternatively, a suitable stabilizing compound can be selected based on the relative difference between the initial water content and the measured water content of the precursor solution containing the stabilizing compound. Alternatively, a suitable stabilizing compound can be selected based on the measured water content of the precursor solution containing the stabilizing compound evaluated at a certain time period after preparation. In some embodiments, the time period after preparation is less than 1 day, 1 day, 3 days, 7 days, 1 month, more than 1 month, or any other desired time interval. In some embodiments, a suitable stabilizing compound includes a species that reduces the water uptake of the organotin species (i.e., has a higher measured water content after a certain time period) compared to an otherwise non-stabilized compound-containing composition. For reference, an equivalent precursor solution containing 4-methyl-2-pentanol solvent without additives can be used. It is believed that slower water uptake indicates reduced hydrolysis of hydrolyzable ligands, which may correlate with cluster formation and precipitation.

[0055] In some embodiments, the stabilized compound enhanced photoresist solution may be filtered to remove particles or insoluble defects. In general, particulates may not be visible and the composition is unknown for the particulates. Some particulates may be sufficiently large clusters of organotin composition, but particulates may be debris from process equipment or impurities of the composition. Regardless of the identity of the particulates, they can be removed by the indicated treatment. Suitable filtration methods are described in the '498 patent application cited above. The precursor solutions described herein can be treated to be very low in particulate contamination and sealed in containers for storage and transport prior to use.

[0056] Particulate contamination in photoresist solutions can generally adversely affect the performance of integrated devices resulting from lithographic patterning using photoresists. For example, small particles can become embedded in the photoresist pattern and create inhomogeneities that can appear as defects (e.g., scum, microbridges, line breaks, etc.) after development or after etching / pattern transfer, thus reducing device yield. As described herein, particulates can include condensed organotin oxo / hydroxo species resulting from hydrolysis / condensation processes in the solution. The additive compositions described herein can disrupt such hydrolysis / condensation processes and thus disrupt the formation of condensed organotin particulates.

[0057] Treatment with precursor solutions As described above, the radiation patternable organotin oxohydroxo composition can be formed using a stability enhanced photoresist solution, and such coatings can be formed using any suitable method known in the art. Spin coating can be particularly desirable for forming coatings using a stabilized compound enhanced photoresist solution. In a typical spin coating process, a quantity of stabilized compound enhanced photoresist solution is introduced to the substrate surface, and the substrate is spun at high speed to drive a rapid evaporation and condensation process, allowing for 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 performed for about 5 seconds to about 5 minutes, and in further embodiments about 15 seconds to about 2 minutes. An initial low speed spin of, for example, 50 rpm to 250 rpm, can be used to perform an initial bulk application of the composition across the substrate. A backside rinse, edge bead removal step, etc., 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.

[0058] A substrate generally refers to a surface on which a coating material can be deposited, and a 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 necessary. Suitable substrate surfaces may include any reasonable material. Some substrates of interest include, for example, silicon wafers, semiconductor 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 in layers. In some embodiments, the substrate may include patterned structures, 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," which is incorporated herein by reference.

[0059] The thickness of the coating may generally be a function of the concentration, viscosity, and rotation speed of the spin coating of the precursor solution. For other coating processes, the thickness may also generally be adjusted by selection of the coating parameters. In some embodiments, it may be desirable to use a thin coating to facilitate the formation of small and high-resolution features in a subsequent patterning process. For example, the coating material after drying may 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, from about 1 nm to about 40 nm in other embodiments, and from about 3 nm to about 25 nm in further embodiments. One of ordinary skill in the art will recognize that additional ranges of thickness within the explicit ranges above are contemplated and are included within the scope of the present disclosure. The thickness may be assessed using non-contact methods of 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, such as highly uniform coatings on substrates of reasonable size, evaluation of the coating uniformity or flatness can be evaluated, for example, with a 1 centimeter edge exclusion, i.e., the coating uniformity is not evaluated within 1 centimeter of the edge of the coating, although other suitable edge exclusions can be selected.

[0060] While heating may not be required for successful application of the 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 where heating of the coated substrate is performed, 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.

[0061] Generally, photoresist coatings can be patterned using radiation. Suitable radiation sources include extreme ultraviolet (EUV), ultraviolet (UV), or electron beam (EB) radiation. For semiconductor device manufacturing, EUV radiation may be desirable due to its higher resolution compared to UV radiation and higher throughput compared to electron beam (EB) based processes. The radiation can be directed to the substrate material, typically through a mask, or the radiation beam can be controllably scanned across the substrate to form a latent image in the resist coating.

[0062] According to the international standard ISO 21348 (2007), which is incorporated herein by reference, ultraviolet light ranges between wavelengths of 100 nm and less than 400 nm. Krypton fluoride lasers can be used as sources of 248 nm ultraviolet light. The ultraviolet range can be subdivided in several ways according to 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 is used for lithography at 13.5 nm, and the light is generated from Xe or Sn plasma sources excited with 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 0.1 nm to less than 10 nm.

[0063] The amount of electromagnetic radiation can be characterized by a fluence or dose, which is given by the integrated radiative flux over the exposure time. For embodiments in which 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 ~Approx. 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.

[0064] Following 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 about 45° C. to about 250° C., in additional embodiments about 50° C. to about 190° 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 additional embodiments about 0.75 minutes to about 10 minutes. One 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 consolidate the exposed areas without decomposing the unexposed areas into metal oxides.

[0065] Following the implementation of the PEB, developing the image 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 acid or base solutions and insoluble in organic solvents; conversely, the non-irradiated areas are generally hydrophobic and therefore soluble in organic solvents and insoluble in aqueous acid or base solutions. For negative imaging, the developer can be an organic solvent, such as the solvent used to form the precursor solution. In general, the choice of developer can be influenced by the solubility parameters for both the irradiated and non-irradiated coating materials, as well as the volatility, flammability, toxicity, viscosity, and potential chemical interactions of the developer 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.

[0066] It has also been discovered that solventless development, also referred to as dry development, can be used with organotin materials. Dry development can include 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. Provisional Patent Application No. 63 / 247,885 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 facilitates removal of the irradiated or non-irradiated areas. Development can be followed by an optional washing step to further remove undesired materials from the pattern, such methods being 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.

[0067] After completion of the development step, including any optional washing, the coating material may be heat treated to further condense the material and to further dehydrate, densify, or remove residual developer from the material. This heat treatment may be particularly desirable in embodiments where the oxide coating material is incorporated into a final device, but it may be desirable to perform the heat treatment in some embodiments where the coating material is used as a resist and is ultimately removed if stabilization of the coating material is desired to facilitate further patterning. In particular, baking of the patterned coating material may be performed under conditions where the patterned coating material exhibits a desired level of etch selectivity. In some embodiments, the patterned coating material 5 may be heated to a temperature of about 100° C. to about 600° C., in further embodiments about 175° C. to about 500° C., and in additional embodiments about 200° C. to about 400° C. Heating may be performed for at least about 1 minute, in other embodiments about 2 minutes to about 1 hour, and in further embodiments about 2.5 minutes to about 25 minutes. Heating may 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 used for similar purposes.

[0068] Such patterning processes are generally steps in device formation that may involve etching and / or depositing a substrate based on a pattern formed in a resist material. Repeated lithography steps can be performed to create stacks of materials to form the desired device. EXAMPLES

[0069] Example 1: Demonstration of an increase in coordination number (CN) The following example demonstrates that the addition of a linear alcohol co-solvent can increase the Sn coordination number of an organotin precursor.

[0070] A series of organotin solutions were prepared by first preparing solvent compositions having specific volumetric ratios of 4-methyl-2-pentanol to n-propanol according to Table 1 below, with each solvent composition standardized to contain a target initial water content of 300 ppm. As used herein, ppm refers to micrograms per milliliter (μg / ml, which is equivalent to ppm by weight when the solvent density is 1 g / ml). As described in the Jiang et al. '876 patent cited above, water standardization was achieved by mixing appropriate known amounts of 4-methyl-2-pentanol or n-propanol with known concentrations of water.

[0071] [Table 1]

[0072] An organotin precursor R1, comprising a mixture of two separate alkyltin tri-tert-amyl alkoxide compounds (e.g., R1Sn(OtAmyl)3 and R2Sn(OtAmyl)3), was then added to each solvent composition to provide a final Sn concentration of 0.05M and mixed thoroughly to form organotin solutions A, 25P, 50P, 75P, and P. There was no evidence of precipitation in the organotin solutions. Aliquots for NMR analysis were prepared by diluting each organotin solution in a 1:1 ratio with C6D6 and then analyzed on a 400 MHz Bruker NMR spectrometer. Immediately after formulation and again after storage at room temperature for 30 days, aliquots of samples A, 25P, 50P, 75P, and P showed low Sn concentrations. 119 S NMR analysis was performed and the corresponding spectra are shown in Figures 1 and 2, respectively. Sample A shows a Sn peak at about -250 ppm, which is consistent with literature reports for the 4-CNSn environment. Conversely, samples 25P, 50P, 75P, and P show a peak at about -460 ppm, which is consistent with literature reports for the 6-CNSn environment. Thus, these results indicate that n-propanol is a Sn 4+The results demonstrate the addition of the fifth and sixth ligands in combination with the linear alcohol. Solvent alkoxy groups may be expected to substitute for the initial alkoxy groups as the solvent concentration shifts the equilibrium accordingly. The results also show no evidence of the addition of fifth or sixth ligands in organotin solutions with only 4-methyl-2-pentanol as the solvent. The results suggest that the increase in coordination number is due, at least in part, to less steric hindrance of the linear alcohol compared to secondary or tertiary solvents. The results further suggest that blending the linear alcohol with another co-solvent can provide a stabilizing effect for organotin solutions.

[0073] Example 2: Reducing water consumption with co-solvents The following example demonstrates that the addition of a linear alcohol co-solvent can reduce the water consumption of an organotin photoresist over time.

[0074] First, a series of solvent compositions containing different volume ratios of 4-methyl-2-pentanol (4M2P) and n-propanol were prepared. One set of solvent compositions was standardized to contain a target initial water content of 300 ppm, and a second set was standardized to contain a target initial water content of 1000 ppm. Water standardization was described in Example 1. After preparation of each standardized solvent composition, Karl Fischer (KF) titration was performed to evaluate the actual initial water content in each solvent composition after standardization and solvent blending. The results are shown in Table 2 below.

[0075] [Table 2]

[0076] Next, an organotin precursor R1, comprising a mixture of two separate alkyltin tri-tert-amyl alkoxide compounds (e.g., R1Sn(OtAmyl)3 and R2Sn(OtAmyl)3), was added to each solvent composition to provide a final Sn concentration of 0.05 M. The solutions were mixed thoroughly to form organotin solution samples 0P1, 25P1, 50P1, 75P1, 100P1, 0P2, 25P2, 50P2, 75P2, and 100P2, as shown in Table 2. After storage in sealed bottles at room temperature for 1 day, 7 days, and 29 days, KF titrations were performed on each sample to determine how much water had been consumed in each sample over time. The results are plotted in Figure 3 for the sample prepared with an initial moisture content of 300 ppm (the "P1" sample) and in Figure 4 for the sample prepared with an initial moisture content of 1000 ppm (the "P2" sample).

[0077] In both figures, it can be seen that the samples containing n-propanol consume much less water than the samples containing only 4M2P. For samples 25P1, 50P1, 75P1, and 100P1, which initially contained about 300 ppm water, the measured water content after one day only slightly decreased to 250 ppm, 224 ppm, 233 ppm, and 285 ppm for 25P1, 50P1, 75P1, and 100P1, respectively. Conversely, the measured water content of 0P1 (e.g., the sample containing only 4M2P) significantly decreased to about 50 ppm after one day. For samples 25P2, 50P2, 75P2, and 100P2, which initially contained about 1000 ppm water, the measured water content after one day had decreased to 268 ppm, 251 ppm, 261 ppm, and 233 ppm for 25P2, 50P2, 75P2, and 100P2, respectively. Conversely, the measured water content of 0P2 (e.g., a sample containing only 4M2P) had decreased significantly to about 70 ppm after one day. In both data sets, samples containing only 4M2P consumed much more water from the solvent than samples containing n-propanol, indicating that linear alcohol co-solvents such as n-propanol can interfere with the hydrolysis of organotin precursor compounds.

[0078] After aging each sample for 7 days, KF measurements were performed again on each sample to determine how much additional water had been consumed during storage. As previously noted, samples 25P1, 50P1, 75P1, and 100P1, with moisture concentrations of 275 ppm, 245 ppm, 254 ppm, and 297 ppm, respectively, all had significantly more free water than 0P1, which had a measured moisture content of 40 ppm. Similarly, samples 25P2, 50P2, 75P2, and 100P2 had measured moisture contents of 209 ppm, 201 ppm, 191 ppm, and 159 ppm after 7 days, while 0P2 had a measured moisture content of 39 ppm after 7 days.

[0079] Finally, after 29 days of storage at room temperature, each sample was reanalyzed by KF titration for measured water content. Samples 25P1, 50P1, 75P1, and 100P1 showed measured water contents of 318 ppm, 282 ppm, 310 ppm, and 345 ppm, respectively, while the non-co-solvent composition sample 0P1 showed a significantly lower measured water content of 24 ppm. Similarly, samples 25P2, 50P2, 75P2, and 100P2 showed measured water contents of 178 ppm, 174 ppm, 165 ppm, and 131 ppm, respectively, while the non-co-solvent composition sample 0P2 showed a significantly lower measured water content of 20 ppm.

[0080] Additionally, it can be seen that the measured water content of the non-co-solvent composition samples 0P1 and 0P2 continued to decrease with time, indicating that the organotin precursor continues to react with and consume water in the non-co-solvent composition. Additionally, referring to Figures 3 and 4, respectively, it can be seen that the measured water content of co-solvent compositions 25P1, 50P1, 75P1, and 100P1 increased as a function of time, while the measured water content of co-solvent compositions 25P2, 50P2, 75P2, and 100P2 decreased as a function of time. This result suggests that ambient water is taken up into the samples over time, and that the samples with an initial water content of 300 ppm are much more resistant to hydrolysis than the samples with higher initial water content. This result suggests that the combination of minimal and controlled initial water content with a linear alcohol co-solvent can provide a more effective impediment to hydrolysis and therefore consumption of free water, although as noted above, the details of the equilibrium can be complex.

[0081] This behavior indicates that non-cosolvent compositions such as 0P1 and 0P2 consume much more water than compositions in which a linear alcohol cosolvent is present, and is evidence that hydrolysis can be hindered in cosolvent-enhanced compositions.

[0082] Example 3: Shelf Life This example illustrates the improvement of the shelf life of an organotin resist solution with various additives.

[0083] Three organotin precursors R1, R2, R3 were used to prepare various additive-enhanced photoresist solutions. R1 comprises a mixture of two alkyltin tri-tert-amyl alkoxide compounds (e.g., R1Sn(OtAmyl)3 and R2Sn(OtAmyl)3), while R2 and R3 comprise, separately, a single and distinct alkyltin tri-tert-amyl alkoxide compound. Three water-standardized stock solvents with different initial water contents were used as dilution solvents to test the propensity of each additive to improve the shelf life and robustness against precipitation of the organotin composition. Water standardization is described in Example 1. For each combination, samples were prepared by first preparing three stock solutions of 4-methyl-2-pentanol (4M2P) with target initial water contents of 300 ppm, 1000 ppm, and 3000 ppm. Control comparisons prepared with 4M2P only were prepared for each additive / 4M2P combination to measure the improvement of each additive.

[0084] All samples were standardized to provide a final Sn concentration of 0.05M. For samples containing additives, the additives were added to the solvent and mixed prior to the addition of organotin precursors R1, R2, and R3. Additives tested to enhance the shelf life of the organotin solutions included acetic acid (AA), formic acid (FA), triethanolamine (TEA), and trifluoroacetic acid (TFA), all tested at two different additive to Sn molar ratios. For example, 1AA represents a composition of 1 mole acetic acid to 1 mole Sn, and 3AA represents a composition of 3 moles acetic acid to 1 mole Sn. The shelf life stability of each additive composition was performed by monitoring each sample for precipitation over a one month period. The results are shown in the table below, with performance ratings of A, B, C, D, and F given as shown in Table 3 below.

[0085] [Table 3]

[0086] The results in Table 3 above show that at the highest moisture concentrations, the three non-additive control compositions have relatively poor stability, forming precipitates in less than one week (R1) or one day (R2 and R3). Furthermore, the non-additive control composition of R2 showed relatively poor stability at each moisture concentration, which is due in part to the relatively poor solubility of the organotin precursor R2 in organic solvents. This result suggests that additives may improve the stability of the R2 solution, in part, by improving the solubility of R2. All but one of the additive samples at the lowest initial moisture content (300 ppm) was stable for more than one month. At an initial moisture content of 1000 ppm, stability appears to be strongly dependent on the additive composition for R3 and on the molar ratio of AA for R1 and R2. The results show that AA, TEA, FA, and TFA can improve stability with respect to precipitate formation at higher initial moisture levels, indicating that these additives can be used to hinder the formation of insoluble species.

[0087] Example 4: Aging and patterning performance This example demonstrates how the presence of a co-solvent or additive mitigates the effects associated with aging of an organotin resist solution exposed to ambient air, as a means to further evaluate the stability of the precursor solution.

[0088] Organotin resist precursor R4 was used in all cases. R4 contained a mixture of alkyltin trialkoxide and tin tetraalkoxide in 4-methyl-2-pentanol to achieve a total Sn concentration of 0.044M, where the tin tetraalkoxide constituted 1% of the total Sn. These samples were not water normalized. Either dimethylurea, methanol, or triethanolamine was added to the 4-methyl-2-pentanol solvent prior to the addition of the R4 precursor to achieve sample concentrations as shown in Table 4. The concentrations of dimethylurea and triethanolamine were in mole % relative to the total amount of Sn. After preparation of each sample, the volume was divided into two sets: a control set and an aged set. The samples in the control set were stored covered in a drawer at room temperature for 7 days, while the samples in the aged set were stored uncovered in a fume hood and exposed to ambient air for 7 days.

[0089] Each sample was then used to prepare radiation patternable coatings. Silicon wafers (100 mm diameter) with native oxide surfaces were used as substrates for thin film deposition. Prior to resist deposition, the substrates were treated with a vapor prime of hexamethyldisilazane (HMDS). The solution was spin-coated onto the substrates at 900 rpm and baked at 100 °C for 2 min to form alkyltin oxide hydroxide resist coatings.

[0090] A linear array of 50 circular pads, approximately 500 um in diameter, was projected onto the wafer using EUV light (Lawrence Berkeley National Laboratory Micro Exposure Tool, MET). Pad exposure times were adjusted to deliver increasing EUV doses (7% exponential steps) to each pad. The resist and substrate were then post-exposure baked (PEB) on a hotplate at 160°C for 2 minutes. The exposed film was immersed in 2-heptanone for 15 seconds and rinsed with 2-heptanone for an additional 15 seconds to produce a negative image; i.e., the unexposed portions of the coating were removed. The remaining resist thickness of the exposed pads was measured using a JAWoollam M-2000 spectroscopic ellipsometer. The measured thickness was normalized to the maximum measured resist thickness and plotted against the logarithm of the exposure dose to produce a characteristic curve for each resist at a range of PEB temperatures. The maximum slope of the normalized thickness vs. log dose curve is defined as the photoresist contrast (γ), and the dose value at which the tangent line through this point is equal to 1 is defined as the photoresist dose-to-gel (Dg). In this way, common parameters used to characterize photoresists can be approximated according to Mack, C. Fundamental Principles of Optical Lithography, John Wiley & Sons, Chichester, UK; pp 271-272, 2007, which is incorporated herein by reference.

[0091] Dose vs. gel values ​​were measured for each set of control and aged samples. The differences in Dg between the control and aged compositions are shown in Table 4 below.

[0092] [Table 4]

[0093] For compositions with co-solvents or additives in Table 4, the dose-to-gel value between the control and aged samples is less than 2%. Conversely, compositions without additives (dimethylurea or triethanolamine) or co-solvents (methanol) showed more than 30% increase in Dg of the aged samples. In other words, these results indicate that the presence of additives or co-solvents, even at low concentrations relative to Sn, can mitigate the aging effect caused by exposure to ambient atmosphere for 7 days, thereby significantly maintaining the reproducibility of patterning performance.

[0094] Example 5: Reducing water consumption with additives The following examples demonstrate that the addition of a diol additive can reduce the water consumption of an organotin photoresist over time.

[0095] A series of additive-enhanced solvent solutions were prepared by dissolving an appropriate mass of ethylene glycol (EG) in 4-methyl-2-pentanol to form 0.05M, 0.1M, and 0.15M solutions, respectively. Prior to adding EG, water was added to the 4-methyl-2-pentanol solvent to obtain a water-normalized 4-methyl-2-pentanol with an initial water content of approximately 1000 ppm as measured by KF titration. After the additive-enhanced solvent solutions were prepared, organotin precursor R1 was then added to each sample and mixed thoroughly to obtain a final Sn concentration of 0.05M in each solution. Samples A1, A2, and A3 had additive to Sn molar ratios of 1.0, 2.0, and 3.0, respectively. A control sample without additive was also prepared to have a Sn concentration of 0.05M in 4-methyl-2-pentanol containing 1000 ppm water. The samples are summarized in Table 5 below.

[0096] [Table 5]

[0097] The organotin precursor R1 comprised a mixture of two alkyltin tri-tert-amyl alkoxide compounds (e.g., R1Sn(OtAmyl)3 and R2Sn(OtAmyl)3). Samples A1, A2, A3, and the control, as described in Table 5 above, were each stored in a sealed bottle at room temperature and KF titrations were performed on each sample at various time points to determine the measured water content at various time points. Samples were measured on the day of compounding, 4 days after compounding, and 13 days after compounding. The amount of water consumed was calculated as the difference between the initial water content (e.g., 1000 ppm) and the measured water content, and the percentage of water consumed was calculated as the amount of water consumed divided by the initial water content. The measured water content and percentage of water consumed for each sample 0 days after compounding, 4 days after compounding, and 13 days after compounding are summarized in Table 6 and displayed graphically in FIG. 5.

[0098] [Table 6]

[0099] The measured water content of A3 and the control was 886 ppm and 378 ppm, respectively, on the day of compounding. The control consumed 62.2% of the 1000 ppm initial water, while A3 consumed only 11.4% of the initial water. Measured water content data was collected for all additive-enhanced samples and controls 4 days after compounding and 13 days after compounding. The results show that less water was consumed in the additive-enhanced solutions than the control solutions at each time period. Additionally, the results show that the percent of water consumed for each sample increased over time, but that the ethylene glycol additive may help slow the process. The results further show that the percent of water consumed decreased as the molar ratio of ethylene glycol to tin increased from 1.0 (A1) to 3.0M (A3), thus adjusting the additive molar ratio can be used to control the hydrolysis of organotin species.

[0100] FIG. 5 graphically illustrates that the measured moisture content of each sample decreased over time, but that at each time period, additive-containing samples A1, A2, and A3 had a higher measured moisture content (e.g., amount of free water) than the control sample.

[0101] The results suggest that the control solution without additives does not interfere relatively with the reaction between the hydrolytically sensitive organotin species and water. In contrast, the ethylene glycol additive competes with water for Sn-binding sites, thereby effectively impeding the hydrolysis of the organotin solution.

[0102] The above embodiments are illustrative and are not intended to be limiting. Additional embodiments are within the scope of the claims. Moreover, 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 herein. Unless otherwise specifically indicated, to the extent that a particular structure, composition and / or process is described herein with components, elements, ingredients, or other categories, the disclosure herein should be understood to encompass the specific embodiment, an embodiment that includes the specific components, elements, ingredients, other categories, or combinations thereof, as well as an embodiment that consists essentially of such specific components, ingredients, or other categories, or combinations thereof, which may include additional features that do not change the basic nature of the subject matter as proposed in this discussion.

Claims

1. an organic solvent and a compound of formula RSnL ３ and an organotin composition represented by one or more organotin compounds represented by the formula: wherein each R is independently a hydrocarbyl ligand having 1 to 31 carbon atoms and each L is independently a hydrolyzable ligand, wherein the total concentration of Sn is from about 0.001 M to about 0.5 M, the solvent comprises a straight-chain alcohol having 1 to 6 carbon atoms, the organotin precursor solution has an initial water content of from about 100 ppm to about 10,000 ppm, and the organotin precursor solution has a reduced rate of water evolution compared to an equivalent organotin precursor solution formed using 4-methyl-2-pentanol.

2. 10. The organotin precursor solution of claim 1, wherein the organic solvent comprises a solvent blend, the linear alcohol is a co-solvent present in a concentration of about 5 vol% to about 75 vol% of the total solvent, and the solution has a room temperature viscosity of about 0.5 cP to about 20 cP.

3. The organotin precursor solution of claim 2 , wherein the co-solvent comprises methanol, ethanol, n-propanol, n-butanol, 1-pentanol, or a mixture thereof.

4. 3. The organotin precursor solution of claim 2, wherein the co-solvent is present in a concentration of about 25% to 55% by volume of the total solvent.

5. At least a portion of the cosolvent contains RSnL as a ligand. ３ The organotin precursor solution of claim 2 , wherein the organotin precursor is coordinated to

6. The solvent comprises a primary alcohol of the formula R'OH, where R' comprises a hydrocarbyl ligand having 1 to 10 carbon atoms, and the solution comprises a hydrocarbyl ligand of the formula RSnL ｙ ([H]OR') ｘ 6. The organotin precursor solution of claim 5, comprising a composition represented by the formula: wherein x is 1 or 2 or a combination thereof, OR′ may or may not be deprotonated, and y is determined according to charge balance.

7. 10. The organotin precursor solution of claim 1, wherein the initial water content is normalized to about 100 ppm to about 5,000 ppm.

8. 10. The organotin precursor solution of claim 1, wherein one week after preparation, the measurable water content is at least about 100 ppm.

9. 10. The organotin precursor solution of claim 1, wherein the organic solvent comprises a secondary or tertiary alcohol or a combination thereof.

10. The organotin precursor solution of claim 1 , wherein the organic solvent comprises 4-methyl-2-pentanol.

11. 10. The organotin precursor solution of claim 1, wherein the organic solvent comprises a blend of two primary alcohols.

12. 10. The organotin precursor solution of claim 1, wherein the organotin precursor solution has no observable precipitation for at least one week when stored in a sealed container.

13. 10. The organotin precursor solution of claim 1, wherein the hydrocarbyl ligand comprises a straight chain alkyl group, a branched alkyl group, a cycloalkyl group, an aryl group, an alkenyl group, an alkynyl group, heteroatom derivatives thereof, or combinations thereof.

14. 10. The organotin precursor solution of claim 1, wherein the organotin composition comprises one or more R ligands selected from t-amyl, t-butyl, isopropyl, n-butyl, methyl, or combinations thereof.

15. 10. The organotin precursor solution of claim 1, wherein the organotin composition has R ligands comprising a blend of linear alkyl ligands and non-linear alkyl ligands.

16. 16. The organotin precursor solution of claim 15, wherein the non-linear alkyl ligand comprises a branched alkyl group, a cycloalkyl group, or an aryl group.

17. 10. The organotin precursor solution of claim 1, wherein the organotin composition has R ligands comprising methyl and t-butyl ligands.

18. 10. The organotin precursor solution of claim 1, wherein the organotin composition has an L ligand comprising a dialkylamide, an alkylsilylamide, an alkoxide, an alkylacetylide, or a combination thereof.

19. 10. The organotin precursor solution of claim 1, wherein the organotin composition has an L ligand comprising methoxide, ethoxide, propoxide, isopropoxide, butoxide, isobutoxide, tert-butoxide, tert-amyloxide, or a combination thereof.

20. SnL' ４ wherein L' is a hydrolyzable ligand that is the same as or different from L, ４ 10. The organotin precursor solution of claim 1, wherein the concentration of is up to 20 mol % of total Sn.

21. 10. The organotin precursor solution of claim 1, further comprising an additive, said additive being present in a concentration of about 0.01 moles to about 3 moles per mole of Sn.

22. 22. The organotin precursor solution of claim 21, wherein the additive comprises a diol, triol, aminoalcohol, amide, or 1,3-diketone.

23. 22. The organotin precursor solution of claim 21, wherein the additive comprises ethylene glycol, propylene glycol, 1,2-butanediol, glycerol, ethanolamine, diethanolamine, triethanolamine, dimethylformamide, dimethylurea, or acetylacetone.

24. 22. The organotin precursor solution of claim 21 , wherein the additive comprises a carboxylic acid represented by the formula R″COOH.

25. The precursor solution has the formula (RSn) １２ O １４ (OH) ８－ｎ (O ２ CR”) ｎ 25. The organotin precursor solution of claim 24, comprising a soluble composition represented by

26. 10. A radiation-patternable film comprising an organotin composition having an oxo-hydroxo network formed from the organotin precursor solution of claim 1 under conditions that allow hydrolysis of the hydrolyzable ligands.

27. The film, when fully hydrolyzed, has the formula RSnO （１．５－（ｘ／２）） (OH) ｘ 27. The film of claim 26, which can be represented by the formula: where 0<x≦3.

28. 22. A radiation-patternable film formed from the organotin precursor solution of claim 21, wherein the radiation-patternable film comprises an additive ligand.

29. an organic solvent, an additive, and a solvent of the formula RSnL ３ wherein each R is independently a hydrocarbyl ligand having 1 to 31 carbon atoms and each L is a hydrolyzable ligand, and an organotin composition represented by one or more organotin compounds represented by the formula: wherein the total concentration of Sn is from about 0.001 M to about 0.5 M, and the additive is present in a concentration of from about 0.01 moles to about 6 moles per mole of Sn, and is not a monofunctional alcohol, and ＋４ An organotin precursor solution that coordinates to

30. 30. The organotin precursor solution of claim 29, wherein the initial water content is about 10,000 ppm or less.

31. 30. The organotin precursor solution of claim 29, wherein the initial water content is from about 100 ppm to about 10,000 ppm, and wherein the organotin precursor solution has an average stability when stored in a sealed container of at least one week longer than a comparable organotin precursor solution without the additive.

32. 30. The organotin precursor solution of claim 29, wherein one week after preparation, the measurable water content is at least about 100 ppm.

33. 30. The organotin precursor solution of claim 29, wherein the organic solvent comprises a primary alcohol, a secondary alcohol, a tertiary alcohol, or a combination thereof.

34. 30. The organotin precursor solution of claim 29, wherein the organic solvent comprises a straight chain alcohol.

35. 30. The organotin precursor solution of claim 29, wherein the additive is present in a concentration of about 0.01 moles to about 0.5 moles per mole of Sn.

36. 30. The organotin precursor solution of claim 29, wherein the additive is present in a concentration of about 0.5 moles to about 6 moles per mole of Sn.

37. At least a part of the additive contains RSnL as a ligand. ３ 30. The organotin precursor solution of claim 29, wherein the organotin precursor is coordinated to

38. 30. The organotin precursor solution of claim 29, wherein the additive comprises a diol, a triol, an aminoalcohol, a diketone, or a mixture thereof.

39. 30. The organotin precursor solution of claim 29, wherein the additive is a linear, branched, or cyclic compound having 1 to 6 carbon atoms.

40. 30. The organotin precursor solution of claim 29, wherein the additive comprises acetic acid, formic acid, trifluoroacetic acid, or a combination thereof.

41. 30. The organotin precursor solution of claim 29, wherein the additive comprises ethylene glycol, propylene glycol, 1,2-butanediol, glycerol, triethanolamine, dimethylformamide, dimethylurea, or acetylacetone.

42. 30. The organotin precursor solution of claim 29, wherein the hydrocarbyl ligand comprises a straight chain alkyl group, a branched alkyl group, a cycloalkyl group, an aryl group, an alkenyl group, an alkynyl group, heteroatom derivatives thereof, or combinations thereof.

43. 30. The organotin precursor solution of claim 29, wherein the organotin composition comprises R ligands selected from t-amyl, t-butyl, isopropyl, n-butyl, methyl, or combinations thereof.

44. 30. The organotin precursor solution of claim 29, wherein the organotin composition has R ligands comprising a blend of linear alkyl ligands and non-linear alkyl ligands.

45. 45. The organotin precursor solution of claim 44, wherein the non-linear alkyl ligand comprises a branched alkyl group, a cycloalkyl group, or an aryl group.

46. 30. The organotin precursor solution of claim 29, wherein the organotin composition has R ligands comprising a blend of methyl and t-butyl ligands.

47. 30. The organotin precursor solution of claim 29, wherein the organotin composition has an L ligand comprising a dialkylamide, an alkylsilylamide, an alkyloxide, an alkylacetylide, or a combination thereof.

48. 30. The organotin precursor solution of claim 29, wherein the organotin composition has an L ligand comprising methoxide, ethoxide, propoxide, isopropoxide, butoxide, isobutoxide, tert-butoxide, tert-amyloxide, or a combination thereof.

49. SnL' ４ wherein L' is a hydrolyzable ligand that is the same as or different from L, ４ 30. The organotin precursor solution of claim 29, wherein the concentration of is up to 20 mol% of total Sn.

50. 30. A radiation patternable film formed from the organotin precursor solution of claim 29, wherein the radiation patternable film comprises an oxo-hydroxo network.

51. 51. The film of claim 50, wherein the oxo-hydroxo network is formed by hydrolysis.

52. The film, when fully hydrolyzed, has the formula RSnO （１．５－（ｘ／２）） (OH) ｘ 51. The film of claim 50, which can be represented by the formula: where 0<x≦3.

53. 1. A method for preparing a stabilized organotin precursor solution, comprising mixing an organotin precursor composition with an organic solvent and a stabilizing compound to form an organotin precursor solution having a tin concentration of about 0.001 M to about 0.5 M, wherein the organotin precursor composition has the formula RSnL ３ wherein each R is independently a hydrocarbyl ligand having 1 to 31 carbon atoms and each L is a hydrolyzable ligand, the organic solvent comprises an organic compound and has a water content of about 10,000 ppm or less before mixing, the stabilizing compound comprises a linear alcohol having 1 to 6 carbon atoms at a concentration of at least about 5 vol. % based on the total solvent, and a stabilizing compound that is not a monofunctional alcohol and is a tin or tin compound. ＋４ and / or a combination thereof.

54. 54. The method of claim 53, wherein the stabilizing compound results in a slower rate of water consumption compared to an equivalent solution formed using 4-methyl-2-pentanol solvent without the stabilizing compound.

55. 54. The method of claim 53, wherein the organic solvent comprises a secondary or tertiary alcohol or a combination thereof.

56. 54. The method of claim 53, wherein the stabilizing compound comprises a diol, triol, aminoalcohol, amide, or 1,3-diketone.

57. 54. The method of claim 53, wherein the additive comprises ethylene glycol, propylene glycol, 1,2-butanediol, glycerol, ethanolamine, diethanolamine, triethanolamine, dimethylformamide, dimethylurea, or acetylacetone.

58. 54. The method of claim 53, wherein the additive comprises a carboxylic acid.

59. 54. The method of claim 53, wherein the hydrocarbyl ligand comprises a straight chain alkyl group, a branched alkyl group, a cycloalkyl group, an aryl group, an alkenyl group, an alkynyl group, heteroatom derivatives thereof, or combinations thereof.

60. 54. The method of claim 53, wherein the organotin precursor composition comprises R ligands selected from t-amyl, t-butyl, isopropyl, n-butyl, methyl, or combinations thereof.

61. 54. The method of claim 53, wherein the organotin precursor composition has R ligands comprising a blend of linear alkyl ligands and non-linear alkyl ligands.

62. 54. The method of claim 53, wherein the organotin precursor composition has an L ligand comprising methoxide, ethoxide, propoxide, isopropoxide, butoxide, isobutoxide, tert-butoxide, tert-amyloxide, or a combination thereof.

63. 54. The method of claim 53, further comprising purifying the organotin precursor composition prior to mixing.

64. 64. The method of claim 63, wherein the purification comprises fractional distillation and / or ultrafiltration.

65. 54. The method of claim 53, further comprising standardizing the water content of the organic solvent to about 10,000 ppm or less prior to mixing.

66. 66. The method of claim 65, wherein the organic solvent has a normalized water content of from about 100 ppm to about 5000 ppm.

67. 66. The method of claim 65, wherein the organic solvent has a normalized water content of from about 100 ppm to about 1000 ppm.

68. 54. The method of claim 53, wherein the stabilized organotin precursor solution has a measurable water content of at least about 100 ppm one week after mixing.

69. 54. The method of claim 53, wherein the stabilized organotin precursor solution has a room temperature viscosity of about 0.5 cP to about 50 cP.

70. 54. The method of claim 53, wherein the stabilized organotin precursor solution has an average stability when stored in a sealed container that is at least one week longer than an equivalent organotin precursor solution without the stabilizing compound.

71. 1. A method for forming an organotin precursor solution, comprising: a solvent composition; and a compound of the formula RSnL ３ wherein each R is independently a hydrocarbyl ligand having 1 to 31 carbon atoms and each L is independently a hydrolyzable ligand, and an organotin composition represented by one or more organotin compounds represented by the formula: ＋４ The method is selected to reduce hydrolysis from trace moisture compared to an equivalent organotin precursor solution formed using 4-methyl-2-pentanol solvent due to more effective ligand formation with 4-methyl-2-pentanol.

72. The slower water consumption rate is ＋４ 72. The method of claim 71, wherein the cation exchange is due to more efficient ligand formation with the cation exchange.

73. 72. The method of claim 71, wherein the organotin precursor solution has an initial water content of from about 100 ppm to about 10,000 ppm.

74. 74. The method of claim 73, wherein the initial moisture content is normalized.

75. 72. The method of claim 71, wherein the selected solvent composition further comprises a secondary or tertiary alcohol or a combination thereof.

76. 76. The method of claim 75, wherein the combining comprises combining the secondary or tertiary alcohol, or a combination thereof, with the organotin composition to form a first mixture, and subsequently combining the first mixture with a linear alcohol, an additive, or both.

77. 72. The method of claim 71, wherein the additive comprises a diol, triol, aminoalcohol, amide, or 1,3-diketone.

78. 72. The method of claim 71, wherein the additive comprises ethylene glycol, propylene glycol, 1,2-butanediol, glycerol, ethanolamine, diethanolamine, triethanolamine, dimethylformamide, dimethylurea, or acetylacetone.

79. 72. The method of claim 71, wherein the additive comprises a carboxylic acid.

80. 72. The method of claim 71, wherein the hydrocarbyl ligand comprises a straight chain alkyl group, a branched alkyl group, a cycloalkyl group, an aryl group, an alkenyl group, an alkynyl group, heteroatom derivatives thereof, or combinations thereof.

81. 72. The method of claim 71, wherein the organotin composition comprises R ligands selected from t-amyl, t-butyl, isopropyl, n-butyl, methyl, or combinations thereof.

82. 72. The method of claim 71, wherein the organotin composition has R ligands comprising a blend of linear alkyl ligands and non-linear alkyl ligands.

83. 72. The method of claim 71, wherein the organotin composition has an L ligand comprising methoxide, ethoxide, propoxide, isopropoxide, butoxide, isobutoxide, tert-butoxide, tert-amyloxide, or a combination thereof.

84. 72. The method of claim 71, further comprising purifying the organotin composition prior to mixing.

85. 85. The method of claim 84, wherein the purification comprises fractional distillation and / or ultrafiltration.

86. 72. The method of claim 71, further comprising standardizing the water content of the selected solvent composition to about 10,000 ppm or less prior to mixing.

87. 87. The method of claim 86, wherein the selected solvent composition has a normalized water content of from about 100 ppm to about 5000 ppm.

88. 87. The method of claim 86, wherein the selected solvent composition has a normalized water content of from about 100 ppm to about 1000 ppm.

89. 72. The method of claim 71, wherein the organotin precursor solution has a measurable water content of at least about 100 ppm one week after mixing.

90. 72. The method of claim 71, wherein the organotin precursor solution has a room temperature viscosity of about 0.5 cP to about 50 cP.

91. 72. The method of claim 71, wherein the organotin precursor solution, when stored in a sealed container, has an average stability of at least one week longer than an equivalent organotin precursor solution without the stabilizing compound.

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