Organotin clusters, solutions of organotin clusters, and applications to high-resolution pattern formation.

Abstract

The present invention provides crystalline compounds, solutions containing the compounds, methods for synthesizing the compounds, and methods for forming patternable coatings. [Solution] Formula R3Sn3(O2CR') 5-x (OH) 2+x A crystalline compound having (μ3-O) is provided, comprising three tin atoms having a central bridging oxygen atom, three tin-bridging carboxylate ligands, two non-bridging carboxylate ligands bonded to tin, and a tin-bridging OH ligand, wherein R comprises a hydrocarbyl group having 1 to 31 carbon atoms, optionally substituted with a heteroatom functional group.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to the concurrently pending U.S. Provisional Patent Application No. 62 / 588,546 (Cardineau et al.), filed on November 20, 2017, entitled "Organometallic Metal Clusters and Application to High Resolution Patterning," which is incorporated herein by reference.

[0002] The present invention relates to an organometallic radiation-sensitive patterning resist composition and a method for forming a resist pattern using the composition, wherein the composition may contain organometallic clusters. The present invention further relates to a precursor solution containing organometallic clusters and a method for synthesizing organometallic clusters. A coating formed by organometallic clusters can be patterned by radiation at low exposure doses to produce structures. [Background technology]

[0003] The fabrication of semiconductor circuits and devices has been accompanied by a continuous reduction in limiting dimensions across generations. As these dimensions shrink, new materials and methods may be desired to meet the demands for fabricating and patterning increasingly smaller features. Patterning generally involves selectively exposing thin layers of radiosensitive material (resist) to form a pattern, which is then transferred to the next layer or functional material. A promising new type of metal-based radioresist has been discovered that is particularly suitable for providing excellent absorption of extreme ultraviolet (EUV) and electron beam radiation while simultaneously providing very high etching contrast. EUV has been found to be an important tool in semiconductor fabrication for obtaining smaller patterned features, and resist compositions that can take advantage of the benefits of EUV may be a valuable element in this endeavor. [Overview of the project]

Means for Solving the Problem

[0004] In a first aspect, the present invention relates to a composition comprising a molecular cluster represented by the formula R3Sn3(O2CR’) 3+x (L) 2-x (OH)2(μ3-O) (where 0 ≦ x ≦ 2; L is a ligand having the formula OR a or SR a and R a is H or an organic group having 1 to 20 carbon atoms; R is a branched or cycloalkyl having 1 to 31 carbon atoms; R’ is H or an alkyl having 1 to 20 carbon atoms).

[0005] In a further aspect, the present invention relates to a solution comprising an organic solvent and a solvated organometallic cluster having the formula R3Sn3(O2CR’) 5-x (L) 2+x (μ3-O) (where 0 ≦ x < 2; R is a branched or cycloalkyl having 1 to 31 carbon atoms; R’ is H or an alkyl having 1 to 20 carbon atoms, and L is a ligand having the formula -OR” and R” is H, an organic group or a combination thereof).

[0006] In another aspect, the present invention relates to a method for patterning a structure comprising exposing a substrate having a radiation-sensitive coating to patterned radiation to form an exposed coating having a latent image, and developing the exposed coating with a suitable developer to form a patterned coating. The radiation-sensitive coating is generally formed by deposition of a solution comprising a molecular cluster represented by the formula R3Sn3(O2CR’) 5-x (L) 2+x (μ3-O) (where 0 ≦ x < 2; R is a branched or cycloalkyl having 1 to 31 carbon atoms, R’ is H or an alkyl having 1 to 20 carbon atoms, and L is a ligand having the formula -OR” and R” is an organic group).

Brief Description of the Drawings

[0007] [Figure 1] Ball and stick image of the three-dimensional structure of the crystalline stannatrimer, ((CH3)3C)3Sn3(O2CH)5(μ3-O), obtained from X-ray diffraction and analysis of the diffractogram. [Figure 2] Plot showing the thermogravimetric analysis of ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) which shows conversion to SnO2 in air. The plots of weight and heat flow are given as a function of temperature. [Figure 3] Plot showing the thermogravimetric analysis of ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) which shows conversion to SnO in argon. The plots of weight and heat flow are given as a function of temperature. [Figure 4] Plot of a set of 1H and 119Sn NMR spectra of ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) in CDCl3. [Figure 5] Electrospray ionization mass spectrum (ESI-MS) of the Sn3 trimer ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) in tetrahydrofuran-25% formic acid solvent, with an expanded inset plot for the major fragment ions shown. [Figure 6] ESI-MS spectrum of the Sn3 trimer ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) in methanol solvent, with an expanded inset plot for the major fragment ions shown. [Figure 7] Atomic force microscopy scan of the pre-irradiation radiation-sensitive film formed using the ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) precursor solution with pre-irradiation baking at 100 °C, along with evaluation of the root mean square (RMS) surface roughness. [Figure 8] Atomic force microscopy scan of the pre-irradiation radiation-sensitive film formed using the ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) precursor solution with pre-irradiation baking at 120 °C. 150 °C or 180 °C [Figure 9]This involves atomic force microscopy scanning of a pre-irradiation radiation-sensitive film formed using a ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) precursor solution by pre-irradiation baking at 150°C, along with evaluation of the root mean square (RMS) surface roughness. [Figure 10] This involves atomic force microscopy scanning of a pre-irradiation radiation-sensitive film formed using a ((CH3)3C)3Sn3(O2CH)5(OH)2(μ3-O) precursor solution by pre-irradiation baking at 180°C, along with evaluation of the root mean square (RMS) surface roughness. [Figure 11] This is a plot of five contrast curves with normalized film thickness plotted as a function of EUV dose, where the radiosensitive film was exposed to one of five post-irradiation baking temperatures before development. [Figure 12] This is a scanning electron microscope image of a patterned resist with 36 nm pitch lines after irradiation with an EUV dose of 100 mJ / cm2 and development. [Modes for carrying out the invention]

[0008] Organotin clusters have been synthesized that typically contain three tin atoms with alkyl ligands, as well as bridging carboxylate ligands, bridging hydroxo ligands, and bridging oxo ligands, providing alternative processing properties that may be advantageous for radiation-based patterning applications. The cluster has three tin atoms, each with one alkyl ligand. In some embodiments, the cluster has one oxygen atom (μ3-O) bridging the three metal atoms, along with 3-5 carboxylate ligands and 4-2 hydroxo ligands, where two ligands are interchangeable between the carboxylate and hydroxo ligands. The tin-alkyl and tin-carboxylate bonds are sensitive to cleavage, such as by radiation exposure. Breakage of these bonds creates a chemical contrast, enabling desired radiation-based patterning. The synthesis of tin clusters is based on a precursor acetylide ligand, and cluster formation is driven by the reaction with selected amounts of carboxylic acid and water, with corresponding carboxylate, hydroxo, and oxo ligands being formed. The non-aqueous solutions formed by the clusters provide coating compositions that are promising in terms of improved precursor solubility, coating quality, and sensitivity compared to other radiation-based organometallic patterning materials.

[0009] Alkyl metal coordination compositions have been found to provide desirable patterning properties when subjected to high-energy radiation, thereby enabling the patterning of very fine features. These compositions are particularly effective for patterning with electron beams or EUV radiation. The use of alkyl-substituted metal coordination compounds in high-performance radiation-based patterning compositions is described, for example, in U.S. Patent No. 9,310,684 (Meyers et al.), entitled "Organometallic Solution Based High Resolution Patterning Compositions," which is incorporated herein by reference. Improvements to these organometallic compositions for pattern formation are described in U.S. Patent Application Publication No. 2016 / 0116839A1, entitled "Organometallic Solution Based High Resolution Patterning Compositions and Corresponding Methods" (Meyers et al.), and U.S. Patent Application Publication No. 2017 / 0102612A1, entitled "Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning" (Meyers et al.), both of which are incorporated herein by reference. The organometallic compositions in these references have a structure based on a single metal part and can be condensed into a metal oxo-hydroxo material during processing.

[0010] The metal clusters having three metal atoms and an organic ligand described herein include a bridging group between two or three metal atoms. The metal cluster compositions are crystalline solids at the time of synthesis, and their structures are determined for each embodiment. The metal cluster compositions are soluble in suitable organic solvents for additional processing. Solutions of metal clusters can be used as radiation resists that can be deposited on a suitable substrate and further processed for patterning. As demonstrated herein, metal cluster-based compositions can be effectively used for patterning and may have processing advantages.

[0011] The tin cluster currently under consideration contains a core of three tin atoms, each having a μ3-center bridging oxygen atom that connects the three tin atoms. Each tin atom has an alkyl ligand. Three bridging (μ2) carboxylate ligands connect each pair of tin atoms. Two additional carboxylate ligands bond to two tin atoms in a non-bridging (Sn-O bond) configuration, and the tin atom without a non-bridging carboxylate ligand bonds to two μ2 hydroxo ligands that bridging that tin atom to each of the other two tin atoms. Therefore, two of the tin atoms have equivalent ligand structures, and the third tin atom has a slightly different ligand structure, but all tin atoms have alkyl ligands (Sn-C bonds) and share two bridging carboxylate ligands. Based on the results of the examples below, it is considered that the two non-crosslinked carboxylate ligands can be readily substituted with non-crosslinked hydroxo ligands and / or alkoxide ligands (Sn-O bonds). As described in detail below, the synthesis involves the reaction of alkyltin tri(alkylacetylide) in a polar organic solvent with a carboxylic acid and water.

[0012] The formation of several tin clusters is described based on the reaction of alkylstanic acid RSn(O)OH. The formation of tin trimers with phosphate ligands is described in Day et al., J.Am.Chem.Soc.1987, Vol.109, 940-941, titled "A New Structural Form of Tin in an Oxygen-Capped Cluster," which is incorporated herein by reference. Other organotin cages are described in Chandrasekhar et al., Organometallics 2005, Vol.24, 4926-4932, titled "Organotin Cages, {[(n-BuSn)3(μ3-O)(OC6H4-4-X)3]2(HPO3)4}, X=H,Cl,Br,and I,in Double O-Capped Structures: Halogen-Bonding-Mediated Supramolecular Formation," which is incorporated herein by reference. Additional synthetic methods based on alkylstanic acids are summarized in the review by Chandrasekhar et al., Coordination Chemistry Reviews, 2002, Vol. 235, 1-52, titled "Organotin assemblies containing Sn-O bonds," which is incorporated herein by reference. This synthetic study based on alkylstanic acids does not imply any specific range of synthetic methods or compositions described herein.

[0013] Metal cluster compounds form crystalline solids after purification by recrystallization or other means. The solid composition can be optionally dissolved at room temperature in a suitable solvent containing a certain amount of carboxylic acid for stabilization, and the resulting solution is suitable as a resist precursor composition. The resist precursor composition may be stable in solution for distribution in patterning applications. As illustrated below, the precursor composition can be used to coat substrates to be patterned. With appropriate processing during and after coating, coated substrates for radiation patterning can be prepared. The following results demonstrate that the resulting coated substrates are suitable for EUV patterning of nanometer-scale features.

[0014] The tin cluster compositions described herein are of the formula R3Sn3(O2CR') 5-x (OH) 2+x The group can be represented as (μ3-O) (where 0 ≤ x < 2; R = branched or cycloalkyl with 1 to 31 carbon atoms; R' = H or alkyl with 1 to 31 carbon atoms). The tin cluster has three tin atoms around a μ3 oxygen atom, where μ3 indicates a configuration bonded to three parts. Three of the five carboxylate ligands are bridged (μ2), and two are not. The μ symbol is not necessarily included in the formula for convenience. The R group can be a linear, branched (including secondary or tertiary at carbon atoms bonded to the metal), or cyclic hydrocarbyl group.

[0015] Each R (alkyl) group is individually bonded to a tin atom and generally has 1 to 31 carbon atoms, 3 to 31 carbon atoms in the case of a secondary-bonded carbon atom, and 4 to 31 carbon atoms in the case of a tertiary-bonded carbon atom. However, in some embodiments, each R group may have 20 or fewer carbon atoms, and in further embodiments, 15 or fewer carbon atoms. As is well known to those skilled in the art, further ranges of carbon number within the ranges expressed above are also conceivable and are included in the disclosure of the present invention. In particular, branched alkyl ligands may be desirable for some pattern-forming compositions, in which case the R-Sn portion of the cluster is R 1 R 2 R 3 It can be expressed as CSn, where R 1 and R 2 R is an alkyl group that independently has 1 to 10 carbon atoms. 3 R is hydrogen or an alkyl group having 1 to 10 carbon atoms. In some embodiments, R 1 and R 2 It can form a cyclic alkyl moiety, R 3 It may be bonded to other groups of the cyclic portion. Suitable branched alkyl ligands include, for example, isopropyl(R 1 and R 2 is methyl, and R 3 (is hydrogen), tert-butyl (R 1 , R 2 and R 3 ( is methyl), tert-amyl (R 1 and R 2 is methyl, and R 3 (is -CH2CH3), sec-butyl (R 1 is methyl, and R 2 is -CH2CH3, and R 3 (is hydrogen), neopentyl (R 1 and R 2 is hydrogen, R 3The cyclic group can be -C(CH3)3, cyclohexyl, cyclopentyl, cyclobutyl, and cyclopropyl. Suitable examples of cyclic groups include, for example, 1-adamantyl (-C(CH2)3(CH)3(CH2)3 or tricyclo(3.3.1.13,7)decane with a metal bond at the tertiary carbon) and 2-adamantyl (-CH(CH)2(CH2)4(CH)2(CH2) or tricyclo(3.3.1.13,7)decane with a metal bond at the 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 only of C and H and containing 1 to 31 carbon atoms. 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), olefin groups (alkenyl, aryl, aryl), or alkynyl groups, or combinations thereof. In further embodiments, suitable R groups may include hydrocarbyl groups substituted with heteroatom functional groups, including cyano, thio, silyl, ether, keto, ester, or halogenated groups, or combinations thereof.

[0016] With respect to the carboxylate ligand O2CR', the formate ligand (O2CH, R'=CH3) is exemplified below. Generally, R' may be linear or branched and have up to 20 carbon atoms, up to 12 carbon atoms in further embodiments, and 10 or fewer carbon atoms in other embodiments. As is well known to those skilled in the art, further ranges of carbon atoms within the ranges expressed above are also conceivable and are included in the disclosure of the present invention. Other particularly suitable carboxylate (or carboxylate) ligands include, for example, the acetate ligand (O2CCH3), the propionate ligand (O2CCH2CH3), the oxalate ligand (O2CCO2H), or combinations thereof.

[0017] Three carboxylate ligands are cross-linked (μ2) and have a Sn-O-CR'-O-Sn structure, which is thought to stabilize the structure. Two carboxylate ligands are not cross-linked and are thought to be interchangeable with, for example, hydroxo(OH) ligands or alkoxide ligands. Therefore, the parameter x in the formula indicates the degree of exchange between the unbranched carboxylate ligands and the hydroxide ligands. The alkoxide ligand is represented by formula OR a It can be expressed by, where R a A group is generally an organic group having 1 to 20 carbon atoms. An organic group refers to an organic moiety such as an alkyl group or cycloalkyl group, which is more generally saturated or unsaturated (alkenyl, alkynyl, or aromatic) and substituted or unsubstituted by a heteroatom. Other low pK groups include ligands for carbonyl amides, carbonyl O in carbamates, or S in thiols. a The ligand may also be suitable for substitution with a non-crosslinked carboxylate ligand. Therefore, the formula for the tin trimer can be generalized based on these substitutions to R3Sn3(O2CR'). 3+x (OH)2(L) 2-x (μ3-O) is obtained, where 0≦x≦2, and L is given by the equation OR a or SR a (In the formula, R a ∫ represents a ligand having 1 to 20 carbon atoms (H or an organic group). The structure of the synthesized cluster is determined by the purified crystalline form, but it may also form an amorphous solid. The core cluster structure is maintained in solution, but the solvent is thought to provide interchangeable ligands such as water or alcohol. When the cluster composition is dissolved in an alcohol solvent, the alkoxide ligands may be substituted, at least to some extent, with non-crosslinked carboxylate ligands and / or hydroxide ligands. If the solution forms a thin coating in the ambient atmosphere, or if the solvent contains a certain amount of water, the carboxylate ligands may be substituted with hydroxide ligands due to exposure to water in the atmosphere or water from the solvent.

[0018] The synthesis of tin clusters can be based on the use of the initial tin reactant alkyltin triacetylide RSn(C≡CR”), where R corresponds to the alkyl group identified above for the alkyl ligand in the cluster. R'' is generally a linear or branched alkyl group and can be cyclic, unsaturated, or aromatic. R'' is a phenyl group in examples. Alkyltin acetylides are acetylide anions (R'C≡C - Alkyl tin triacetides can be synthesized by adding ) to RSnCl3, adding an alkyl anion to Sn(C≡CR”)4, or by the reaction of HC≡CR” with RSn(NR”'2)3. Alkyl tin triacetides are reacted with a carboxylic acid and a small amount of water in a polar solvent. Generally, the solvent may be an alcohol such as ethanol, or another water-miscible organic solvent. The amounts of carboxylic acid and water are selected to provide trimer cluster formation. Generally, the molar ratio of carboxylic acid to water is about 3 to about 18, about 5 to about 15 in further embodiments, and about 7 to about 14 in other embodiments. As is well known to those skilled in the art, further ranges of carboxylic acid-to-water ratios within the ranges expressed above are also conceivable and are included in the disclosure of the present invention.

[0019] To carry out the reaction, heat can be applied to accelerate the dissolution of alkyltin triacetide. In the following examples, the solution is heated at 60°C for 10 minutes to dissolve the reactants. The temperature can be selected to any desired value lower than the boiling point of the solvent, and the time can be selected based on the dissolution of the reactants. The temperature of the heating step does not appear to be important for cluster formation. The reaction for cluster formation can be carried out overnight, but longer or shorter times may be suitable. In general, the reaction for cluster formation can be carried out for at least about 30 minutes, at least about 1 hour in further embodiments, and about 90 minutes to about 2 days in other embodiments. As is well known to those skilled in the art, further ranges within the ranges expressed above are also conceivable and are included in the disclosure of the present invention. The reaction can be carried out at room temperature, but some heating or cooling may be used if desired.

[0020] The product can be collected by evaporation of the solvent, which is generally carried out under reduced pressure to allow for lower temperatures. The collected solid can be recrystallized for purification, generally from an organic solvent, by heating the solvent to dissolve the composition and slowly cooling the solution. Suitable solvents for recrystallization include, for example, toluene, acetonitrile, ethanol, methanol, and acetone. The recrystallized composition can be collected for further use and optionally washed with a suitable solvent. Based on experiments, the exchange of at least some of the non-crosslinked carboxylate ligands may be due to exchange with alkoxy ligands during recrystallization in an alcoholic solvent.

[0021] To form a resist precursor solution, the cluster composition can be dissolved in a suitable organic solvent. Solubility has been found in chloroform, alcohols, and various polar organic solvents using formic acid or other carboxylic acids as stabilizers at concentrations of about 1% to 25% v / v, and in further embodiments, about 5% to 20% v / v (volume added per total volume of mixture). The alcohol may be one or more of 1-methoxy-2-propanol, 4-methyl-2-pentanol, cyclopentanol, methanol, ethanol, n-propanol, or isopropanol, or mixtures thereof. The alkyltin trimer composition is also soluble in a formic acid solution mixed with one or more of polar ethers, such as tert-butyl methyl ether and anisole, ethyl lactate, or cyclic ethers, such as tetrahydrofuran. Other organic solvents based on the solvents identified above may also be suitable. The tin concentration may range from about 0.1 mM to about 1 M, in further embodiments from about 0.5 mM to about 500 mM, and in other embodiments from about 1 mM to about 100 mM (depending on the amount of tin). Generally, the choice of organic solvent may be influenced by solubility parameters, volatility, flammability, toxicity, viscosity, and possible chemical interactions with other processing materials. Generally, the amount of added carboxylic acid may correspond to the acid form of the carboxylate ligand. Thus, in the case of the illustrated cluster, formic acid may be added to the solution. As is well known to those skilled in the art, further ranges of concentrations within the ranges expressed above are also conceivable and are included in the disclosure of the present invention. Generally, the precursor solution can be thoroughly mixed by using a suitable mixing apparatus appropriate to the volume of material to be formed. Contaminants or other components that do not dissolve properly can be removed using suitable filtration.

[0022] In the above solution, the two non-crosslinked carboxylate ligands may be substituted with other ligands such as alkoxides or sulfur analogs. Therefore, the cluster formula is R3Sn3(O2CR'). 3+x (OH)2(L) 2-x (μ3-O)(where 0≦x≦2, L is OR) a or SR a And Ra (as specified above). Substituted tin trimer clusters can form in solution, but the solvent can be removed to form the corresponding solid.

[0023] The coating material can be formed by deposition, and then the precursor solution is treated on a selected substrate. When using the precursor solutions described herein, some hydrolysis and condensation generally occur during coating, but may be completed by subsequent steps, such as heating in air, or further post-coating may be performed. The substrate generally provides a surface on which the coating material can be deposited, and the substrate may consist of multiple layers, where the surface is the uppermost layer. In some embodiments, the substrate surface may be treated to provide a surface for adhesion of the coating material. Furthermore, the surface may be cleaned and / or appropriately smoothed. Suitable substrate surfaces can include any reasonable material. Some substrates of particular interest include, for example: silicon wafers, silica substrates, other inorganic materials, such as ceramic materials, polymer substrates, such as organic polymers, composites thereof, and combinations thereof on the entire surface and / or in layers of the substrate. Wafers, such as relatively thin cylindrical structures, are convenient, but structures of any reasonable shape can also be used. Polymer substrates or substrates having a polymer layer on a non-polymeric structure may be desirable in certain applications because they are low-cost and flexible, and suitable polymers can be selected because they can be used at relatively low processing temperatures for processing the patternable materials described herein. Suitable polymers include, for example, polycarbonates, polyimides, polyesters, polyalkenes, copolymers thereof, and mixtures thereof. Generally, substrates are desirable to have a flat surface, especially in high-resolution applications. However, in certain embodiments, the substrate may have substantially topography, in which case the resist coating is used to fill and planarize features for specific patterning applications.

[0024] In general, any suitable solution coating process can be used to deliver the precursor solution to the substrate. Suitable coating approaches include, for example, spin coating, spray coating, dip coating, knife-edge coating, vapor deposition methods such as chemical vapor deposition (CVD) or atomic layer deposition (ALD), and printing approaches such as inkjet printing and screen printing. In some of these coating approaches, a pattern of the coating material is formed during the coating process, but the resolution that can be obtained from printing and the like is significantly lower than the resolution that can be obtained from radiation-based patterning described herein.

[0025] When pattern formation is performed using radiation, spin coating can be a desirable approach for relatively homogeneous coverage of the substrate, although edge effects may occur. In some embodiments, the wafer is rotated at a speed of about 500 rpm to about 10,000 rpm, in further embodiments about 1,000 rpm to about 7,500 rpm, and in even later embodiments about 2,000 rpm to about 6,000 rpm. By adjusting the spinning speed, the desired coating thickness can be obtained. Spin coating can be carried out over a period of about 5 seconds to about 5 minutes, in further embodiments about 15 seconds to about 2 minutes. Initially, a low-speed spin, for example, 50 rpm to 250 rpm, can be used to perform initial bulk spreading of the composition across the entire substrate. All edge beads can be removed by performing back-side rinsing, edge bead removal steps, etc., using water or other suitable solvents. As is well known to those skilled in the art, further ranges of spin coating parameters within the ranges expressed above are also conceivable and are included in the disclosure of the present invention.

[0026] The thickness of the coating can generally be a function of the concentration and viscosity of the precursor solution and the spin velocity of the spin coating. In other coating processes as well, the thickness can generally be adjusted by selecting coating parameters. In some embodiments, it is desirable to use a thin coating to facilitate the formation of fine, high-resolution features in the subsequent patterning process. For example, the dried coating material can have the following average thicknesses: about 10 microns or less, about 1 micron or less in other embodiments, about 250 nanometers (nm) or less in further embodiments, about 1 nanometer (nm) to about 50 nm in even later embodiments, about 2 nm to about 40 nm in other embodiments, and about 3 nm to about 35 nm in some embodiments. As is well known to those skilled in the art, further ranges of thickness within the ranges expressed above are also conceivable and are included in the disclosure of this invention. The thickness can be evaluated using non-contact methods, X-ray reflectivity and / or ellipsometry based on the optical properties of the film. Generally, the coating is relatively homogeneous and easy to process. In some embodiments, the variation in coating thickness is less than or equal to ±50% of the average coating thickness, in further embodiments less than or equal to ±40%, and in even later embodiments less than or equal to ±25% of the average coating thickness. For example, in some embodiments such as highly homogeneous coating on a larger substrate, the evaluation of coating homogeneity is often performed by excluding 1 centimeter from the edge, i.e., the homogeneity of the coating is not evaluated in the portion of the coating within 1 centimeter from the edge. As is well known to those skilled in the art, further ranges within the ranges expressed above are also conceivable and are included in the disclosure of the present invention.

[0027] The coating process itself involves the evaporation of some of the solvent because many coating processes form droplets or other shapes of the coating material to obtain a large surface area and / or move the solution to promote evaporation. As the solvent is lost, the concentration of chemical species in the material increases, and the viscosity of the coating material tends to increase. The purpose of the coating process is to remove as much of the solvent as possible and stabilize the coating material for the next processing step. Reactive chemical species condense during coating or subsequent heating, forming hydrolyzed coating materials.

[0028] Generally, coating materials can be exposed to atmospheric moisture before radiation exposure and optionally heated to hydrolyze the hydrolyzable bonds to the metal in their precursor composition and / or further expel the solvent, thereby promoting the densification of the coating material. After in-situ hydrolysis, the coating material can generally form polymeric metal oxo-hydroxo and / or carboxylate networks (in which the metal has several ligands) based on the bonding of oxo-hydroxo and / or carboxylate ligands to the metal, or form molecular solids consisting of polynuclear metal oxo / hydroxo and / or carboxylate species containing alkyl ligands.

[0029] The hydrolysis / solvent removal process may or may not be quantitatively controlled for the precise stoichiometry of the heated coating material and / or for a specific amount of solvent remaining in the coating material. Furthermore, the formulas and compositions expressed herein may include some additional water, either directly bonded to Sn or as hydrogen-bonded components of the network. Generally, experimental evaluation of the properties of the thus obtained coating material is performed to enable the selection of processing conditions effective for the patterning process. While heating is not necessary for the successful application of the process, it is desirable to heat the coated substrate to increase the processing speed and / or improve the reproducibility of the process and / or facilitate the evaporation of reaction products from hydrolysis, such as amines and / or alcohols. In embodiments in which heat is applied in pre-exposure baking for the purpose of removing the solvent, the coating material may be heated to a temperature of about 45°C to about 250°C, and in further embodiments to about 55°C to about 225°C. Heating for solvent removal can generally be carried out for at least about 0.1 minutes, in further embodiments for about 0.5 minutes to about 30 minutes, and in even further embodiments for about 0.75 minutes to about 10 minutes. As is well known to those skilled in the art, further ranges of heating temperatures and times within the ranges expressed above are also conceivable and are included in the disclosure of the present invention. As a result of the heat treatment, hydrolysis, and densification of the coating material, the coating material can exhibit an increase in refractive index and radiation absorption without a significant decrease in contrast.

[0030] Following hydrolysis, condensation, and drying, the coating material can be finely patterned using radiation. As described above, the composition of the precursor solution and the corresponding coating material can be designed to absorb the desired form of radiation sufficiently, taking into account the benefits of EUV radiation in particular. The absorption of radiation provides energy that can break the bonds between the metal and the alkyl ligands, and thus at least some of the alkyl ligands are no longer available for stabilizing the material. Similarly, the absorption of radiation can break the bonds between the metal and the carboxylate ligands and / or decompose the carboxylate ligands. The products of the radiolysis reaction, including alkyl ligands or other fragments, can or cannot diffuse out of the film, depending on the process variables and the identification of such reaction products. Upon absorbing a sufficient amount of radiation, the exposed coating material condenses, i.e., forms a higher-grade metal oxo-hydroxo network, which may contain additional water absorbed from the ambient atmosphere. Radiation can generally be delivered according to a selected pattern. The radiation pattern is converted into a latent image, which corresponds to the irradiated and unirradiated regions within the coating material. The irradiated regions contain chemically altered coating material, while the unirradiated regions generally contain the coating material as it was originally formed. As will be explained below, developing the coating material to remove the unirradiated coating material, or alternatively, selectively remove the irradiated coating material, can create extremely smooth edges.

[0031] Radiation can generally be directly shone onto a coated substrate through a mask, or the radiation beam can be scanned over the substrate in an adjustable manner. Common examples of radiation include electromagnetic radiation beams, electron beams (beta rays), or other suitable radiation. Generally, electromagnetic radiation beams can have a desired wavelength or wavelength range, such as visible light, ultraviolet light, or X-rays. The resolution achievable with a radiation pattern generally depends on the wavelength of the radiation; generally, using shorter wavelengths of radiation yields higher resolution patterns. Therefore, it is preferable to use ultraviolet light, X-rays, or electron beams to obtain particularly high resolution patterns.

[0032] According to the international standard ISO 21348 (2007), which is incorporated herein by reference, ultraviolet light refers to wavelengths between 100 nm and less than 400 nm. A krypton fluoride laser can be used as a light source for 248 nm ultraviolet light. The ultraviolet range can also be further subdivided in several ways in accepted standards; for example, 10 nm to less than 121 nm is extreme ultraviolet (EUV), and 122 nm to less than 200 nm is far ultraviolet (FUV). The 193 nm line from an argon fluoride laser can be used as a radiation source for FUV. 13.5 nm EUV light has been used for lithography, generated from a Xe or Sn plasma source excited using a high-energy laser or discharge pulse. Soft X-rays can be defined as wavelengths between 0.1 nm and less than 10 nm.

[0033] The amount of electromagnetic irradiation can be characterized by fluence or dose, which is defined by the integrated radiant flux during the exposure time. A suitable radiant fluence is about 1 mJ / cm². 2 ~Approx. 175mJ / cm 2 In further embodiments, approximately 2 mJ / cm² 2 ~Approx. 150mJ / cm 2 In further embodiments, approximately 3 mJ / cm² 2 ~Approx. 125mJ / cm 2This is possible. As is well known to those skilled in the art, further ranges of radiant fluence within the ranges expressed above are also conceivable and are included in the disclosure of this invention.

[0034] Based on the design of the coating material, a large contrast in the properties of the material can be made between the irradiated area (where the coating material is condensed) and the unirradiated area (where the coating material is substantially unchanged in terms of organic or carboxylate ligands). In embodiments using post-irradiation heat treatment, the post-irradiation heat treatment can be carried out at temperatures of about 45°C to about 250°C, in further embodiments about 50°C to about 190°C, and in even later embodiments about 60°C to about 175°C. Post-exposure heating can generally be carried out for at least about 0.1 minutes, in further embodiments about 0.5 minutes to about 30 minutes, and in even later embodiments about 0.75 minutes to about 10 minutes. As is well known to those skilled in the art, further ranges of post-irradiation heating temperatures and times within the ranges specified above are also conceivable and are included in the disclosure of the present invention. The high contrast performance in this material makes it easy to form high-resolution lines with smooth edges in its patterns, which will be discussed in the next section.

[0035] In the case of negative-toned image formation, the developer may be an organic solvent, such as the solvent used to form the precursor solution. Generally, the following factors influence the selection of the developer: solubility parameters with respect to the coating material, both when irradiated and when not irradiated, as well as the developer's volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials. Particularly suitable developers include, for example, alcohols (e.g., 4-methyl-2-pentanol, 1-butanol, isopropanol, 1-propanol, methanol), ethyl lactate, ethers (e.g., tetrahydrofuran, dioxane, anisole), etc. Development can be carried out for about 5 seconds to about 30 minutes, in further embodiments about 8 seconds to about 15 minutes, and in subsequent embodiments about 10 seconds to about 10 minutes. As is well known to those skilled in the art, further ranges within the ranges expressed above are also conceivable and are included in the disclosure of the present invention.

[0036] In addition to the main developer composition, the developer may include additional compositions to facilitate the developing process. Suitable additives may include, for example, viscosity modifiers, solubilizing agents, or other processing aids. If optional additives are present, the developer may contain additives in a range of about 10% by weight or less, and in further embodiments, about 5% by weight or less. As is well known to those skilled in the art, further ranges of additive concentrations within the ranges expressed above are also conceivable and are included in the disclosure of this invention.

[0037] When using weaker developers, such as low-concentration aqueous developers, diluted organic developers, or compositions with slower coating development speeds, a higher temperature development process can be used to increase the processing speed. With stronger developers, the speed can be reduced and / or the dynamics of development can be adjusted by lowering the temperature of the development process. Generally, the development temperature should be adjusted within a range appropriate to the volatility of the solvent. Furthermore, developers that dissolve the coating material near the developer-coating interface can be dispersed using ultrasound during development.

[0038] Developers can be applied to patterned coating materials using various rational approaches. For example, the developer can be sprayed onto the patterned coating material. Spin coating can also be used. In automated processing, the paddle method can be used, in which the developer is poured onto a certain form of coating material. If necessary, the development process can be completed using spin rinsing and / or drying. Suitable rinsing solutions include, for example, ultrapure water, methyl alcohol, ethyl alcohol, propyl alcohol, and combinations thereof. After the image has been developed, the coating material is arranged as a pattern on the substrate.

[0039] After the development process is complete, the coating material can be heat-treated to further condense, dehydrate, and densify the material, or to remove any remaining developer. This heat treatment may be particularly desirable in embodiments where the oxide coating material is incorporated into the final device, but it is also 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 pattern formation. In particular, baking of the patterned coating material can be performed under conditions where the patterned coating material exhibits a desired level of etch selectivity. In some embodiments, the patterned coating material can be heated to a temperature of about 100°C to about 600°C, in further embodiments about 175°C to about 500°C, and in even later embodiments about 200°C to about 400°C. Heating can 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 is preferably performed in air, vacuum, or in an inert gas atmosphere, such as Ar or N2. As is well known to those skilled in the art, further ranges of temperatures and times for heat treatment within the ranges specified above are also conceivable and are included in the disclosure of the present invention. Similarly, non-heat treatments, such as blanket UV exposure or exposure to an oxidizing plasma such as O2, may also be employed in the same process.

[0040] In some embodiments, adjacent linear segments of a closely spaced structure may have an average pitch (half-pitch) of about 60 nm or less (30 nm or less in half-pitch), in some embodiments about 50 nm or less (25 nm or less in half-pitch), and in further embodiments about 34 nm or less (17 nm or less in half-pitch). The pitch can be evaluated from the design and confirmed using scanning electron microscopy (SEM), for example, top-down imaging. As used herein, “pitch” refers to the spatial period or center-to-center distance of repeating structural elements, and “half-pitch” is half the pitch, as commonly used in the art. Feature dimensions of a pattern can also be described in relation to the average width of the features, which is generally evaluated from corners, etc. Furthermore, “feature” can refer to gaps between and / or to material elements. The average width can be about 25 nm or less in some embodiments, about 20 nm or less in further embodiments, and about 15 nm or less in even further embodiments. As is well known to those skilled in the art, further ranges of pitch and average width within the ranges expressed above are also conceivable and are also included in the disclosure of the present invention. Based on these processes, pattern formation can generally be adapted through a repetitive pattern formation process to form appropriately layered structures, such as transistors or other elements, thereby forming various devices, such as electronic integrated circuits.

[0041] Wafer throughput is a substantial limiting factor in the implementation of EUV lithography in mass-production semiconductor manufacturing, directly related to the dose required to pattern a given feature. However, despite the existence of chemical strategies to reduce imaging dose, a negative correlation between the imaging dose required to print the target feature and feature size homogeneity (e.g., LWR) is commonly observed in EUV photoresists with feature sizes and pitches less than 50 nm, thereby limiting the availability of the final device and wafer yield. Patterning capability can be expressed in terms of dose versus gel value. The imaging dose requirement can be evaluated by forming an array of exposed pads, where the exposure time is stepped for each pad to vary the amount of exposure. The film is then developed, and the thickness of the remaining resist for all pads can be evaluated, for example, using spectroscopic ellipsometry. The measured thicknesses can then be normalized against the maximum measured resist thickness and plotted against the logarithm of the exposure dose to create a characteristic curve. The maximum slope of the logarithmic dose curve for normalized thickness is defined as the photoresist contrast (γ), and the dose value at which the tangent line drawn through this point is equal to 1 is the photoresist dose versus gel value (D). g ) is defined as follows. In this way, the 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. [Examples]

[0042] Example 1. Preparation of the trimmer (t-Bu)3Sn3(O2CH)5(OH)2O This example demonstrates the synthesis of a tin cluster composition.

[0043] First, the reactants for cluster formation were synthesized. A 3 L round-bottom flask was equipped with a magnetic stirrer and a thermometer and purged with nitrogen. An aqueous acetic acid bubbler was attached to the flask to collect the released dimethylamine. Next, 505 g of phenylacetylene and 1 L of hexane were added to the flask. While stirring vigorously, 462 g of tert-butylsutris(dimethylamide) was added, maintaining the temperature below 50°C. Rapid release of the amine occurred through the addition. Once complete, stirring was stopped, and the flask was left overnight to crystallize. The crystals of tert-butylsutris(phenylacetylide) were collected and recrystallized in hexane (698.6 g / yield 97.2%).

[0044] 50 g of synthesized tert-butyltin tri(phenylacetylide), 375 mL of anhydrous ethanol, 125 mL of 92% formic acid (8% water), and an additional 5 mL of deionized water were placed in a 500 mL round-bottom flask equipped with a magnetic stirrer. The solution in the round-bottom flask was heated at 60°C for 10 minutes, or until the acetylide dissolved, and then stirred overnight at room temperature. After the overnight reaction, the solvent was distilled under vacuum. Following the removal of the solvent, the recovered solid was dissolved in 500 mL of hot toluene (80°C), and the solid was recrystallized by slowly cooling the solution to 25°C. Colorless crystals were collected by filtration (yield 82%).

[0045] The colorless crystals were characterized using X-ray diffraction, differential scanning calorimetry, NMR, and electrospray ionization mass spectrometry. The characterization of the composition is shown in Figures 1-6. Figure 1 is Bruker TMThis is the predicted crystal structure of the crystalline product obtained by X-ray diffraction using the SHELXL-2014 package (Bruker Corporaton) (see Sheldrik, GM (2008) Acta.Crst.A64, 112-122). The structure shows a μ3-O atom bridging three tin atoms. Each tin atom has a t-butyl ligand, and the three bridging formate ions bond each pair of tin atoms. Two OH groups bridge one tin atom with the other, resulting in two equivalent tin atoms and one identifiable tin atom. The two unbridging formate ions are ligands for the two equivalent tin atoms. The following NMR results are consistent with the fact that in the crystalline environment, two tin atoms are equivalent and one tin atom is distinctly different.

[0046] Figures 2 and 3 show differential scanning calorimetry of the crystals. The thermogravimetric analysis in Figure 2 was obtained in an ambient air atmosphere, and the thermogravimetric analysis in Figure 3 was obtained in argon gas. Figure 2 demonstrates the formation of the final SnO2, and Figure 3 demonstrates the formation of the final SnO, which are evaluated according to their final weight. The results also provide heat flow results that indicate several thermal steps in the process to reach the final product.

[0047] The NMR spectrum in Figure 4 was obtained using a 500 MHz Bruker-Ascend NMR spectrometer with a 5 mm BBOF probe. 1 H and 119 A Sn channel was used. Data were analyzed using MestReNova v.12 NMR software. The tin spectrum shows two resonances with integral values ​​of 1:2 at -550 and -571 ppm, indicating two tin environments and a total of three tin (or 3x) environments. The proton NMR spectrum shows a broad hump for the formate proton at 8.44 ppm and another broad hump for the hydroxyl proton at 6.11 ppm. The peaks at 1.6 and 1.1 ppm correspond to the tert-butyl peak at 1.4 ppm. 119 / 117 These are Sn satellites. The precise shift of these peaks is sensitive to the water content in the solvent, suggesting interaction with water.

[0048] Figures 5 and 6 are the electrospray ionization mass spectra of the product tin trimer obtained from solution. Figure 5 was obtained from a solution of 1 mM tin tetrahydrofuran in 25% formic acid solvent, and Figure 6 was obtained from a solution of 1 mM tin in methanol. Both drawings were collected in an Agilent 1200LC liquid chromatograph configured with an autoinjector and flowed directly into an Agilent ESI-QTOF 6510. Both spectra suggest rapid exchange between the two uncrosslinked formates and either water or methanol.

[0049] Example 2. Preparation of coated wafers This example describes the preparation of a coated wafer for EUV pattern formation.

[0050] Crystalline tin trimers from Example 1 were dissolved in a mixed solvent of 95% anhydrous anisole and 5% formic acid (99% formic acid containing 1% water) at concentrations ranging from 1.9 to 9.4 mM. The molar concentration refers to the number of tin atoms, not the number of moles of trimer, which is customary in this field.

[0051] A radiation-sensitive film was deposited on a silicon wafer to a thickness of 25 nm by spin-coating a tin trimer solution in 5% formic acid / anisole with an 8.6 mM tin concentration in air at 1500 rpm for 45 seconds. Four coated wafers were pre-baked for 60 seconds at either 100°C, 120°C, 150°C, or 180°C. After baking, the films were examined using atomic force microscopy (AFM), and the root mean square surface roughness values ​​were found to be between 0.16 nm and 12 nm. The AFM results for the four baking temperatures described above are shown in Figures 7-10. At baking temperatures of 100°C or 120°C, the films were atomically smoothed. At higher temperatures, grain growth was observed, resulting in surface roughness.

[0052] Example 3. Film exposure and EUV contrast This example relates to the evaluation of the contrast curve of a prepared radiosensitive film.

[0053] A set of coated wafers with radiosensitive films was prepared as described above. The films were exposed to an EUV Direct Contrast Tool (13.5 nm) at Lawrence Berkeley National Laboratory, and the contrast was assessed. Prior to exposure, the films were baked at 80°C for 60 seconds. Selected areas of each wafer were exposed with increasing doses. In particular, the pad arrays had exposure times adjusted to stepwise deliver the EUV dose to each pad along the array. After exposure, the films on various wafers were baked (post-exposure baking) at a temperature selected between 80°C and 150°C, and then the exposed wafers were developed with 2-heptanone after baking. The remaining thickness of each exposed pad on the developed wafer was assessed by spectroscopic ellipsometry. The measured thicknesses were normalized against the maximum measured resist thickness and plotted against the logarithm of the exposure dose to create characteristic curves for each resist at a series of post-exposure baking temperatures. Figure 8 shows the contrast curves obtained for each post-exposure baking temperature.

[0054] Example 4. Negative image formation by EUV exposure This example demonstrates the ability to form high-resolution patterns using tin cluster precursors.

[0055] The 5% formic acid / anisole resist precursor solutions described in Examples 2 and 3 were dispensed onto a silicon substrate having a native oxide surface, spin-coated at 1500 rpm for 45 seconds, and then baked on a hot plate at 100°C for 120 seconds. The coated substrate was exposed using a Berkeley Microfield Exposure Tool with 13.5 nm wavelength radiation, dipole illumination, and a numerical aperture of 0.3. The exposed resist and substrate were then post-exposure baked on a hot plate at 170°C for 120 seconds. The exposed wafer was immersed in 2-heptanone for 15 seconds to remove unexposed areas of the resist, and then dried. Figure 9 shows an SEM image of the resulting 36 nm pitch line / space pattern. Thus, the cluster-based resist material is demonstrated to be suitable for nanometer-scale EUV pattern formation.

[0056] The embodiments described above are for illustrative purposes only and do not limit this specification. Additional embodiments exist in the claims. In addition, while the present invention has been described in relation to specific embodiments, variations in form and detail can be made without departing from the spirit and scope of the invention, as will be readily apparent to those skilled in the art. Any incorporation of the references above is limited and does not incorporate any subject matter contrary to the express disclosure herein. To the extent that a particular structure, composition and / or process is described herein using components, elements, components or other partitions, unless otherwise specifically stated, the disclosure herein is understood to encompass embodiments that include specific embodiments, specific components, elements, components, other partitions or combinations thereof, and embodiments that substantially consist of such specific components, components, other partitions or combinations thereof, including additional features that do not alter the fundamental essence of the subject matter as suggested in the description.

Claims

1. Formula R ３ Sn ３ (O ２ CR') ３＋ｘ (L) ２－ｘ (OH) ２ (μ ３ -O)(where 0 ≤ x ≤ 2; L is a ligand having the formula OR ａ or SR ａ ; R ａ is H or an organic group having 1 to 20 carbon atoms; R = branched or cycloalkyl having 1 to 31 carbon atoms; R' = H or alkyl having 1 to 20 carbon atoms) A composition containing a molecular cluster represented by.

2. The composition according to claim 1, wherein the composition is crystalline.

3. The composition according to claim 2, wherein x = 2.

4. The composition according to any one of claims 1 to 3, wherein R comprises a branched alkyl group, a cycloalkyl group, or a mixture thereof.

5. The composition according to any one of claims 1 to 3, wherein R is a methyl, ethyl, i-propyl, n-butyl, s-butyl, or t-butyl group, t-amyl, neopentyl, or a combination thereof.

6. The composition according to any one of claims 1 to 5, wherein R' comprises H, an alkyl group having 1 to 10 carbon atoms, or a combination thereof, and L is OH.

7. A method for synthesizing the composition according to any one of claims 1 to 6, A method comprising reacting an alkyltin trialkyl acetylide with a carboxylic acid and water in an organic solvent.

8. Organic solvent and formula R ３ Sn ３ (O ２ CR') ５－ｘ (L) ２＋ｘ (μ ３ A solution comprising a solvated organometallic cluster having the formula -OR'' (where 0 ≤ x ≤ 2; R = branched or cycloalkyl having 1 to 31 carbon atoms; R' = H or alkyl having 1 to 20 carbon atoms, and L is a ligand having the formula -OR'', where R'' is H, an organic group or a combination thereof).

9. The solution according to claim 8, wherein the organic solvent comprises an alcohol, an ether, an ester, or a mixture thereof.

10. The solution according to claim 9, wherein the organic solvent further comprises about 5 v / v% to about 25 v / v% of a carboxylic acid.

11. The solution according to any one of claims 8 to 10, having a cluster concentration of approximately 1.9 mM to approximately 9.4 mM based on the amount of tin.

12. The solution according to any one of claims 8 to 11, wherein R comprises a methyl, ethyl, i-propyl, n-butyl, s-butyl, or t-butyl group, t-amyl, neopentyl, or a combination thereof.

13. The solution according to any one of claims 8 to 12, wherein R' comprises H, an alkyl group having 1 to 10 carbon atoms, or a combination thereof, and L is OH.

14. R" is -R ０ OHR １ The solution according to any one of claims 8 to 13, comprising an alkyl group having 1 to 10 carbon atoms or a combination thereof.

15. A method for patterning structures, A step of exposing a substrate having a radiosensitive coating to patterned radiation to form an exposure coating having a latent image, wherein the radiosensitive coating is of formula R ３ Sn ３ (O ２ CR') ３＋ｘ (L) ２－ｘ (OH) ２ (μ ３ Step and The exposed coating is developed with an appropriate developer to form a patterned coating, and A method that includes this.

16. The method according to claim 15, wherein the radiation is EUV radiation.

17. The method according to claim 15 or 16, wherein R comprises a methyl, ethyl, i-propyl, n-butyl, s-butyl, or t-butyl group, t-amyl, neopentyl, or a combination thereof.

18. The method according to any one of claims 15 to 17, wherein R' comprises H, an alkyl group having 1 to 10 carbon atoms, or a combination thereof, and L is OH.

19. R" is -R ０ OHR １ The method according to any one of claims 15 to 18, comprising an alkyl group having 1 to 10 carbon atoms or a combination thereof.

20. The method according to any one of claims 15 to 19, wherein the developer comprises an organic solvent for forming a negative pattern.

Images