Organometallic Metal Chalcogenide Clusters and Applications to Lithography

Abstract

Patterning with UV and EUV light using organotin sulfide (and selenide) clusters is described. These clusters are solid at room temperature and soluble in moderately polar organic solvents. Irradiation can stabilize the irradiated material by either breaking carbon-metal bonds or crosslinking unsaturated organic moieties. The irradiated material then becomes resistant to dissolution in organic solvents, allowing non-irradiated material to be contacted with an organic solvent to develop the radiation-formed latent image. Radiation-patternable layers can be formed through solution coating or vapor deposition. Corresponding precursor solutions, structures, and methods are described.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 62 / 876,842, filed Jul. 22, 2019, by Cardineau et al., entitled "Organometallic Metal Chalcogenide Clusters and Application to Lithography", which is incorporated herein by reference.

[0002] The present invention relates to organometallic photoresist compositions and methods of using these compositions to form photoresist coatings and patterns.

Background Art

[0003] In semiconductor manufacturing, patterning of materials is performed to fabricate devices and circuits. These patterned structures are generally formed by repeated photolithography processes of thin - film deposition, radiation exposure, and etching steps to form a large number of devices in a small area. Technological advancements can be accompanied by an increase in device density, which may be desirable for performance improvements.

[0004] Thin - film coatings of organic and organometallic compositions can be used as radiation - sensitive photoresists. Radiation can change the chemical structure and composition of the photoresist, thereby affecting its dissolution rate in a selected solvent. The pattern of radiation can be replicated as a latent image in the photoresist coating and then as a patterned photoresist structure by selective dissolution of unexposed and exposed regions. This patterned photoresist structure can then be transferred to a substrate, typically an active or passive device layer, by an etching process.

Summary of the Invention

Problems to be Solved by the Invention

[0005] For the development of latent images in a photoresist, a liquid developer can be particularly effective. The substrate can be selectively etched through the resulting windows or gaps in the photoresist layer or a desired material can be deposited within the exposed windows or gaps. Functional materials such as conductors and dopants can be deposited or incorporated using chemical vapor deposition, physical vapor deposition, ion implantation, and other desired methods. Finally, the patterned photoresist, when completely removed. This process is repeated many times to form additional layers of the patterned material. In semiconductor manufacturing, EUV lithography has been introduced to obtain very small feature and device sizes for improving circuit functionality. In this type of lithography, there is a need for a new type of photoresist that effectively absorbs radiation having a wavelength of 13.5 nm.

Means for Solving the Problems

[0006] In a first aspect, the present invention relates to a formulation of (RSn)4X6 (where R is an organic or hydrocarbyl group and X is S or Se) in an organic solvent that can form a continuous and smooth photoresist coating. The formulation can be a pattern-forming precursor solution comprising an organic solvent and an organotin cluster composition represented by the formula (RSn)4X6 (where R is an organic ligand bonded to Sn by a metal-carbon bond and X is S or Se), and the precursor solution has a concentration of about 0.0005 M to about 1 M based on tin.

[0007] In a second aspect, the present invention relates to a coated substrate comprising a radiation-sensitive film of (RSn)4X6 having an average thickness of 1 micron or less and having a thickness variation of 25% or less from the average at any location across the film. This coating comprises a metal sulfide (selenide) network having a metal cation with an organic ligand by a metal-carbon bond or a metal-sulfide-oxide-hydroxide network having a metal cation bonded to an organic ligand via a metal-carbon bond. In some embodiments, this aspect can be described as a structure having a radiation-sensitive pattern-forming layer comprising a substrate and a radiation-sensitive layer comprising an organic tin cluster represented by the formula (RSn)4X6, where R is an organic ligand having 1 to 15 carbon atoms bonded to Sn by a metal-carbon bond, and X is S or Se, and this radiation-sensitive layer has an average thickness of about 2 nm to about 1 micron.

[0008] In a third aspect, the present invention relates to a method of patterning a radiation-sensitive coating of (RSn)4X6, comprising irradiating a coated substrate with radiation along a selected pattern to form a radiation-irradiated structure having a region of the radiation-irradiated coating and a region of the non-radiation-irradiated coating, and selectively developing the radiation-irradiated coating to remove a substantial portion of the non-radiation-irradiated region. The coated substrate generally comprises a coating comprising a metal-sulfide cluster or metal-sulfide network having a metal cation with an organic ligand by a metal-carbon bond, or a metal-sulfide-oxide-hydroxide network having a metal cation bonded to an organic ligand via a metal-carbon bond. In particular, this aspect can be described as a method of patterning a coating, comprising developing a pattern from a virtual image formed by exposing a radiation-sensitive layer to a radiation pattern to form a radiation-irradiated layer. Development of the pattern can include contacting the radiation-irradiated layer with an organic solvent to substantially remove the non-radiation-irradiated portion of the radiation-irradiated layer, the radiation-sensitive layer being formed using an organotin cluster, and the radiation irradiation of the radiation-sensitive layer resulting in a material that is substantially less soluble in the organic solvent.

[0009] In a further aspect, the present invention relates to a method of forming a radiation-sensitive layer suitable for patterning on a substrate surface, comprising depositing a (RSn)4X6 cluster on the substrate, where X is S or Se, and R is a hydrocarbyl group (or organic ligand) bonded to Sn by a metal-carbon bond. The deposition step comprises 1) contacting a solution comprising a (RSn)4S6 cluster and an organic solvent with the substrate surface, and removing the solvent to form a layer of radiation-sensitive coating material, 2) volatilizing the (RSn)4X6 cluster, and collecting the volatilized cluster on the substrate surface, or 3) Performing reactive deposition of (RSn)4X6 using the vapor and gas H2X of (RSn)4Y6, where Y is a halogen atom may be included.

Brief Description of Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

DETAILED DESCRIPTION OF THE INVENTION

[0011] Improved properties are obtained in high-resolution radiation-based patterning with organotin clusters, and the tin tetramers described herein are suitably processable for use in EUV lithography. The clusters are formed as tetrameric species having crosslinkable thio groups and attendant alkyl groups, providing cluster stability. The tin tetramer, which is an amorphous solid at room temperature, is soluble in suitable organic liquids. The patterning formulation is described based on the dissolution of the tin tetramer in an organic solvent and the deposition of a uniform and functional coating on a suitable substrate. EUV patterning with desirable properties is demonstrated.

[0012] The manufacture of semiconductor circuits and devices has been accompanied by a regular decrease in critical dimensions over successive generations. As these dimensions decrease, new materials and methods may be required to meet the requirements for processing and patterning ever smaller feature sizes. Patterning generally involves the selective exposure of a thin layer of radiation-sensitive material (photoresist) to form a pattern and then transfer it to subsequent layers and functional materials. Metal-based resists exhibit good absorption of extreme UV light and electron beam radiation, while at the same time providing a particularly suitable new class of materials for obtaining very high etching contrast.

[0013] The use of alkyl-substituted metal coordination and cluster compounds that form oxohydroxo networks has been found to be a very promising patterning material in high-performance radiation-based patterning, particularly in extreme ultraviolet patterning. Alkyl metal patterning compositions are described, for example, in U.S. Patent No. 9,310,684 to Meyers, entitled "Organometallic Solution Based High Resolution Patterning Compositions", which is incorporated herein by reference. Improvements to these organometallic compositions for patterning are described in U.S. Patent No. 10,642,153 B1 to Meyers, entitled "Organometallic Solution Based High Resolution Patterning Compositions and Corresponding Methods" and U.S. Patent No. 10,228,618 B1 to Meyers, entitled "Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning", both of which are incorporated herein by reference. The organotin clusters described herein involve substitution of oxohydroxo ligands with sulfide ligands, and the results herein indicate that sulfide compositions can provide similarly desirable patterning results in EUV patterning.

[0014] One of the organometallic precursor solutions desirable for high-resolution EUV lithography exhibits a shelf life that supports the distribution of the product, adheres to the preferred substrates, results in a uniform and smooth thin film coating, and is highly sensitive and responsive to radiation exposure. Desirable compositions of these solutions can include metal sulfides of organometals of the (RSn)4S6 type dissolved in an organic solvent, where R is a hydrocarbyl ligand having 1 to 15 carbon atoms that is bonded to tin via an Sn-C bond. In particularly interesting embodiments, the organotin sulfide can be dissolved in a polar solvent such as tetrahydrofuran (THF) or a combination of THF and anisole that functions as a vehicle for uniformly coating a substrate by spin coating and related methods. In further embodiments, these coatings can be exposed to a pattern of UV light or EUV light to induce a chemical change that makes the exposed regions more resistant to dissolution in an organic developer than the unexposed regions. This behavior, where the photoresist exposed on the substrate remains after development, is characteristic of a negative-type material.

[0015] Tin clusters having alkyl and crosslinkable dianionic chalcogenides (S, Se) for forming adamantane structures have been synthesized to date. Examples of the synthesis and characterization of (RSn)4X6 (X = S or Se) can be found in the following papers, all of which are incorporated herein by reference: R = methyl, n-butyl, t-butyl, phenyl. G. A. Costa, M. C. Silva, G. M. de Lima, R. M. Logo, M. T. C. Sansiviero, Thermal decomposition of sulfur-containing organotin molecular precursors to produce pure-phase SnS. Phys. Chem. Chem. Phys. 2, 5708-5711 (2000). R = (Me3Si)3C. K. Wraage, T. Pape, R. Herbst-Irmer, M. Noltemeyer, H.-G. Schmidt, H. W. Roesky, Synthesis of (RSn)4X6 adamantanes (X = O, S, Se) in liquid ammonia in the two-phase system liquid ammonia / THF. European Journal of Inorganic Chemistry 5, 869 - 872 (1999). R = 4-(CH2=CH)-C6H4. N. Rosemann, J. P. Eussner, A. Beyer, S. W. Koch, K. Volz, S. Dehnnen, S. Chatterjee, A highly efficient directional molecular white-light emitter driven by a continuous-wave laser diode. Science 352, 1301 - 1304 (2016).

[0016] (RSn)4(S,Se)6 clusters have four metal (metalloid) atoms with one organic ligand bonded to the metal (metalloid) via a metal (metalloid)-carbon bond. Figure 1 shows the structure of one embodiment of an organotin sulfide cluster. In some embodiments, the cluster includes a dianionic chalcogen (e.g., thio) ligand shared between two Sn centers. The tin-carbon bond is sensitive to radiation-induced cleavage, which can induce different dissolution rates and enable radiation-based pattern formation as desired. Alternatively, the R group can include an unsaturated alkenyl moiety that is crosslinkable by radiation exposure. It is expected that a negative-tone lithography pattern based on the change in solubility of the radiation-irradiated material will be formed by both the initial bond cleavage and crosslinking processes. The non-aqueous solution formed using the cluster provides a promising coating composition with improved precursor solubility, coating quality, and sensitivity compared to another radiation-based organometallic pattern-forming material.

[0017] Synthesis of clusters and formation of coating solution (RSn)4S6 compositions can be prepared by the direct reaction of mono-organic tin trichloride with sodium sulfide in THF. Examples describe the synthesis of derivatives where R = butyl and butenyl. The following reaction: 4RSnCl3 + 6Na2S = (RSn)4S6 + 12NaCl mixes the reagents in a 4:6 stoichiometric ratio. A solution of RSnCl3 in THF is added to a cooled solution (-78 °C) of Na2S in THF to effect the reaction. Hydrogen sulfide (H2S) can be used in place of sodium sulfide. The precipitated solid NaCl is removed by filtration. Similar reactions can be carried out using Na2Se to form selenide cluster compounds (RSn)4Se6, and the following discussion can be adapted, mutatis mutandis, to the selenides and considered to be correspondingly and explicitly disclosed. Next, the solvent is evaporated to give the solid (RSn)4S6, which can then be dissolved in CH2Cl2 and passed through a silica plug to remove impurities. Subsequently, the solvent is evaporated to give the purified compound, which can be triturated under pentane and recovered by filtration to give a free-flowing white solid. The following examples show the synthesis for the case where R = n-butyl (C4H9) or R =.n-butenyl (C4H7). Some mono-organic tin trichloro precursor compounds are commercially available and others can be synthesized using available protocols, an example of which is discussed in the examples.

[0018] The R (organic) group can be a hydrocarbyl group such as a straight-chain, branched (i.e., secondary or tertiary at the metal-bonded carbon atom) or cyclic hydrocarbyl group. Each R group, individually, generally has from 1 to 31 carbon atoms, in the case of a secondary-bonded carbon atom, from 3 to 31 carbon atoms, and in the case of a tertiary-bonded carbon atom embodiment, from 4 to 31 carbon atoms and has, for example, methyl, ethyl, propyl, butyl and branched alkyl. In particular, R 1 R 2 R 3 CSnX3 where R 1 and R 2is, independently, an alkyl group having 1 to 10 carbon atoms, and R 3 is preferably a branched alkyl ligand capable of representing the compound in another expression (wherein is hydrogen or an alkyl group having 1 to 10 carbon atoms). In some embodiments, R 1 and R 2 can form a cyclic alkyl moiety, and R3 can also be bonded to another group of the cyclic moiety. Suitable branched alkyl ligands are, for example, isopropyl (where R 1 and R 2 are methyl and R 3 is hydrogen), tert-butyl (where R 1 , R 2 and R 3 are methyl), tert-amyl (where R 1 and R 2 are methyl and R 3 is -CHCH3), sec-butyl (where R 1 is methyl, R 2 is -CHCH3 and R 3 is hydrogen), 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 bonded to the metal at the tertiary carbon) and 2-adamantyl (-CH(CH)2(CH2)4(CH)2(CH2) or tricyclo(3.3.1.13,7)decane bonded to the metal at the secondary carbon). In another embodiment, the hydrocarbyl group can include an aryl group or an alkenyl group, such as a benzyl group, an allyl group or an alkynyl group. In another embodiment, the hydrocarbyl ligand R can consist of only C and H and can include any group containing 1 to 31 carbon atoms. For example, linear or branched alkyl ( i Pr, t Bu, Me, n(b) It is a cycloalkyl (cyclopropyl, cyclobutyl, cyclopentyl), olefin (alkenyl, aryl, allyl) or alkynyl group or a combination thereof. In a further embodiment, suitable R groups include hydrocarbon groups substituted with heteroatom functional groups such as cyano group, thio group, silyl group, ether group, keto group, ester group or halogenated group or a combination thereof.

[0019] The solid (RSn)4S6 product can be dissolved in a suitable solvent at room temperature or by gentle heating (35 - 65 °C) to obtain a coating composition. The clusters are generally soluble in a wide range of organic solvents. These can be dissolved, for example, in organic solvents such as benzene, toluene, chlorotoluene, 1,1,2-trichloroethane, tetrahydrofuran (THF), anisole and THF-anisole mixtures, mixtures thereof, etc. Generally, the choice of organic solvent can be influenced by solubility parameters, volatility, flammability, toxicity, viscosity and chemical interaction with the substrate. In particular, THF and THF-anisole mixtures enable the deposition of smooth and uniform (RSn)4S6 coatings. As a photoresist in the case of radiation-based pattern formation, the precursor solution can generally contain from about 0.0005 M to about 1.0 M of tin atoms, in a further embodiment from about 0.00025 M to about 0.6 M of tin atoms, and in a further embodiment from about 0.01 M to about 0.40 M of tin atoms. This solution can be applied to the substrate by spin coating or other suitable techniques. Those skilled in the art will recognize that further ranges of concentrations within the explicitly stated ranges above are contemplated and that they fall within the scope of the present disclosure. Generally, the precursor solution can be thoroughly mixed using a suitable mixing device to form the appropriate amount of material. Appropriate filtration can be used to remove contaminants, small particles and other components that do not dissolve properly.

[0020] A coating material can be formed by depositing a precursor solution on a selected substrate and performing subsequent processing. The substrate generally provides a surface on which the coating material can be deposited, and the substrate can include a plurality of layers associated with the top layer within the surface. Suitable substrate surfaces can include any suitable material. Some substrates of particular interest include inorganic materials such as silicon wafers, silica substrates, and other ceramics, organic polymers, their composite materials, and combinations thereof, across the surface of the substrate and / or within the layers of the substrate. Wafers such as relatively thin cylindrical structures can be convenient, but any suitable shaped structure can be used. Substrates having a polymer layer on a polymer substrate or non-polymer structure may be desirable for certain applications based on lithography performance or the cost and flexibility of the substrate, and suitable polymers can be selected based on the relatively low processing temperatures that can be used for the processing of the patternable materials described herein. Suitable polymers can include, for example, polycarbonate, polyimide, polyester, polyalkene, their copolymers, or mixtures thereof. Generally, particularly for high-resolution applications, it is desirable for the substrate to have a flat surface. However, in certain embodiments, for certain pattern formation applications, the substrate can have a substantial topography where filling or planarization of features by a resist coating is intended.

[0021] Formation of coating Generally, the precursor can be supplied to the substrate using any suitable solution or vapor-phase coating method. Suitable coating methods include, for example, spin coating, spray or aerosol coating, dip coating, slot die coating, knife edge coating, printing methods such as inkjet printing and screen printing, and deposition of volatile compounds, vapor deposition such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). In some of these coating methods, a pattern of the coating material is formed during the coating process. However, currently, the resolution obtained by printing, etc. is much lower than the resolution obtained by radiation-based patterning as described herein. The thickness of the layer deposited as a result can be adjusted by using coating parameters and adjusting the solution concentration. The dry coating thickness is determined by the undried coating thickness and concentration.

[0022] When pattern formation is performed by radiation-based lithography, spin coating can be a desirable method for uniformly covering a substrate, but this uniformity can be impaired by the formation of beads near the edge of the substrate. In some embodiments, the substrate can be rotated at a speed of about 500 rpm to about 10,000 rpm, in further embodiments about 1000 rpm to about 7500 rpm, and in further embodiments about 2000 rpm to about 6000 rpm. The rotation speed can be adjusted so that a desired coating thickness is obtained. Spin coating can be performed for a time of about 5 seconds to about 5 minutes, and in further embodiments about 15 seconds to about 2 minutes. An initial low-speed rotation of, for example, 50 to 250 rpm can be used to first spread the entire composition across the substrate. A backside rinse, an edge bead removal step, etc. can be performed using a suitable organic solvent to remove the edge beads. Those skilled in the art will contemplate further ranges of spin coating parameters within the stated ranges and will recognize that they are within the scope of the present disclosure. The cleaning of the bead edges of the organometallic pattern-forming material is described in U.S. Patent No. 10,627,719 to Waller et al., entitled "Methods Of Reducing Metal Residue In Edge Bead Region From Metal-Containing Resists", which is incorporated herein by reference.

[0023] Regarding vapor-based deposition, some compounds can be heated in an inert atmosphere to achieve an appropriate vapor pressure for forming a desired thin coating. The substrate surface can be placed at an appropriate close position to receive the vapor of the compound. The heating for forming the volatile compound can exceed 400 °C and can be 450 °C to 1000 °C in some embodiments. Those skilled in the art will recognize that further ranges of temperatures within the explicitly stated ranges above are contemplated and that they fall within the scope of this disclosure. Alternatively or in addition, vapor deposition can be performed using chemical vapor deposition or atomic layer deposition. Atomic layer deposition is basically a stepwise CVD deposition in which a layer of organotin trihalide is deposited and then reacted with a gas of hydrogen sulfide (or selenide), and then this is repeated to obtain the desired coating thickness. These reactive deposition methods can be realized using the vapor of organotin trihalide together with a gaseous hydrogen sulfide (or hydrogen selenide). These deposition methods can be carried out in an appropriate CVD reaction chamber or the like.

[0024] The coating process itself can result in the evaporation of some of the solvent and / or the movement of the solution to stimulate evaporation, since many coating processes form droplets or other forms of the coating material over a larger surface area. As the solvent decreases, the concentration of the chemical species in the material increases, so the viscosity of the coating material tends to increase. One of the purposes during the coating process can be to remove enough solvent to stabilize the coating material for further processing. The coating species can react with air, hydrolyze, or condense during the coating or subsequent heating to form a chemically modified coating material.

[0025] To select processing conditions effective for a pattern formation process, generally, an empirical evaluation of the properties of the resulting coating material can be performed. Although heating may not be necessary for the process to be used without problems, heating of the coated substrate may be desirable to accelerate the process and / or enhance the reproducibility of the process and / or accelerate the vaporization of volatile by-products. In embodiments where heat is applied to evaporate the solvent during the pre-exposure bake, the coating material can be heated to a temperature of about 45°C to about 250°C, and in further embodiments about 55°C to about 225°C. The heating for removing the solvent can generally be carried out over at least about 0.1 minute, and in further embodiments about 0.5 minute to about 30 minutes, and in further embodiments about 0.75 minute to about 10 minutes. The final film thickness is determined by the baking temperature and time and the initial concentration of the precursor. In the example, a linear relationship between the film thickness and the precursor concentration is shown. Those skilled in the art will recognize that further ranges of heating temperature and time within the explicitly stated ranges above are contemplated and that they fall within the scope of the present disclosure. As a result of the heat treatment of the coating material, possible hydrolysis and densification, the coating material can exhibit an increase in refractive index and an increase in radiation absorption without substantially reducing the contrast in dissolution rate.

[0026] The undried coating thickness is determined by the deposition process. For further processing, the solvent is generally removed, leaving a solid layer as the coating on the substrate. The solution concentration and process conditions affect the dried coating thickness, and by selecting this, the desired pattern formation characteristics can be realized. The average dried coating thickness can be about 2 nm to about 1000 nm, and in further embodiments about 3 nm to about 300 nm, and in further embodiments about 3 nm to about 80 nm. In the case of vapor deposition described later, the coating thickness can be adjusted correspondingly according to the process conditions to achieve the desired layer thickness of the coating. Those skilled in the art will recognize that further ranges of average thickness within the explicitly stated ranges above are contemplated and that they fall within the scope of the present disclosure.

[0027] Pattern formation After drying and possible hydrolysis, a fine pattern can be formed in the coating material using radiation. As described above, the composition of the precursor solution and thus the corresponding composition of the coating material can be designed so that the desired form of radiation (EUV radiation is of particular interest) is sufficiently absorbed. Absorption of the radiation provides energy that can break the bonds between the metal and the alkyl ligands, such that at least some of the alkyl ligands are no longer available to stabilize the material so that tin sulfide / selenide is formed. Instead, absorption of the high-energy radiation can initiate a coupling (polymerization) reaction between the unsaturated centers in the R ligands bonded to adjacent tin sulfide / selenide clusters. Having alkyltin ligands in the sulfide clusters may make the radiation-induced modification less distinct, but the composition is confirmed to provide good pattern formation properties. Radiation decomposition products such as alkyl ligands or other fragments may or may not diffuse out of the film, depending on the process variables and the nature of such products. When a sufficient amount of radiation is absorbed, the exposed coating material condenses, i.e., forms a network with increased cross-linking, which may contain additional water absorbed from the surrounding atmosphere. The radiation can generally be supplied by a selected pattern. The radiation pattern is transferred into a corresponding pattern or latent image of irradiated and non-irradiated regions in the coating material. The irradiated regions contain the chemically changed coating material, and the non-irradiated regions generally contain the coating material as formed. The coating material can be developed to remove the non-irradiated coating material or selectively remove the irradiated coating material to form very smooth edges.

[0028] Radiation can generally be directed at a substrate coated through a mask or the radiation beam can be controllably scanned across the substrate. Generally, radiation can include electromagnetic radiation, an electron beam (beta rays) or other suitable radiation. Generally, electromagnetic radiation can have a desired wavelength or wavelength range such as visible light, ultraviolet light, extreme ultraviolet light or X-ray radiation. The resolution achievable with a radiation pattern generally depends on the radiation wavelength, and higher resolution patterns can generally be achieved using shorter wavelength radiation. Thus, it may be desirable to use ultraviolet light, extreme ultraviolet light or X-ray radiation or electron beam irradiation, particularly to achieve particularly high resolution patterns.

[0029] According to international standard ISO 21348 (2007), which is incorporated herein by reference, ultraviolet light extends over wavelengths of 100 nm or more and less than 400 nm. A krypton fluoride laser can be used as a source of 248 nm ultraviolet light. The ultraviolet range can be further divided in several ways based on approved standards, such as extreme ultraviolet (EUV) from 10 nm or more to less than 121 nm and far ultraviolet (FUV) from 122 nm or more to less than 200 nm. The 193 nm line from an argon fluoride laser can be used as a radiation source for FUV. 13.5 nm EUV light is used in lithography and this light is generated from a Xe or Sn plasma source excited using a high energy laser or a discharge pulse. Soft X-rays can be defined from 0.1 nm or more to less than 10 nm.

[0030] The amount of electromagnetic radiation can be characterized by the fluence or dose defined by the radiation flux integrated over the exposure time. Generally, a suitable EUV radiation fluence is from about 1 mJ / cm 2 to about 175 mJ / cm 2 , in a further embodiment from about 2 mJ / cm 2 to about 150 mJ / cm 2 , in a further embodiment from about 3 mJ / cm 2 to about 125 mJ / cm 2It is possible. Those skilled in the art will consider further ranges of radiation fluence within the above-specified ranges and will recognize that they are within the scope of the present disclosure.

[0031] Based on the design of the coating material, a large contrast in the properties of the material can be induced between the radiation-irradiated region and the non-radiation-irradiated region of the coating material. In embodiments where post-radiation heat treatment is used, the post-radiation heat treatment can be carried out at a temperature of about 45°C to about 250°C, in a further embodiment about 50°C to about 190°C, and in a further embodiment about 60°C to about 175°C. The heating after exposure can generally be carried out for at least about 0.1 minute, in a further embodiment about 0.5 minute to about 30 minutes, and in a further embodiment about 0.75 minute to about 10 minutes. Those skilled in the art will consider further ranges of the heating temperature and time after radiation within the above-specified ranges and will recognize that they are within the scope of the present disclosure. Due to this high contrast in the properties of the material, as described in the following section, the formation of high-resolution lines with smooth edges in the developed pattern becomes even easier.

[0032] In the case of negative image formation, the developer can be an organic solvent such as the solvent used for the formation of the precursor solution. Generally, the choice of the developer can be affected by the solubility parameters for both the radiation-irradiated and non-radiation-irradiated coating materials, as well as the volatility, flammability, toxicity, viscosity of the developer, and potential chemical interactions with other process materials. In particular, suitable developers include, for example, ethyl lactate, ethers (e.g., tetrahydrofuran (THF), dioxane, anisole), ketones (e.g., 2-pentanone, 3-pentanone, hexanone, 2-heptanone, octanone), etc. It is demonstrated in the examples that THF and THF-anisole mixtures are preferred developers. The development can be carried out for about 5 seconds to about 30 minutes, in a further embodiment about 8 seconds to about 15 minutes, and in a further embodiment about 10 seconds to about 10 minutes. Those skilled in the art will consider further ranges within the above-specified ranges and will recognize that they are within the scope of the present disclosure.

[0033] In addition to the main developer composition, the developer can include additives to facilitate the development process. Suitable additives can include, for example, viscosity modifiers, solubilizing aids, or other processing aids. If optional additives are present, the developer can include up to about 20 weight percent of additives, in a further embodiment up to about 10 weight percent of additives, and in a further embodiment up to about 5 weight percent of additives. Those skilled in the art will recognize that further ranges of additive concentrations within the ranges specified above are contemplated and that they fall within the scope of this disclosure.

[0034] When using a weaker developer with a slower development rate for the coating, a higher temperature development process can be used to increase the speed of the process. When using a stronger developer, the temperature of the development process can be decreased to reduce the rate of development and / or control the reaction rate. Generally, the development temperature can be adjusted between appropriate values compatible with the volatility of the solvent. Additionally, a developer having dissolved coating material near the developer-coating interface can be dispersed using sonication during development.

[0035] The developer can be applied to the patterned coating material using any suitable method. For example, the developer can be sprayed onto the patterned coating material. Spin coating can also be used. In the case of automated processing, in a stationary mode, a paddle method involving pouring the developer onto the coating material can be used. Optionally, spin rinsing and / or drying can be used to complete the development process. Suitable rinse solutions can include, for example, ultrapure water, aqueous tetraalkylammonium hydroxide, methyl alcohol, ethyl alcohol, propyl alcohol, and combinations thereof. After development of the image, the coating material is disposed on the substrate as a pattern.

[0036] After the development step, the coating material can be heat-treated to effect further condensation and further dehydration of the material, densification, or removal of residual developer from the coating. This heat treatment may be particularly desirable in embodiments where the coating material is incorporated into the final device, but may also be desirable in cases where stabilization of the coating material is desired to facilitate further patterning, in some embodiments where the coating material is used as a resist and is ultimately removed. 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 from about 80° C. to about 600° C., in further embodiments from about 175° C. to about 500° C., and in further embodiments from about 200° C. to about 400° C. The heating can be carried out for at least about 1 minute, in another embodiment from about 2 minutes to about 1 hour, and in further embodiments from about 2.5 minutes to about 25 minutes. The heating can be carried out in air, in vacuo, or in an inert gas environment such as Ar or N2. Those skilled in the art will recognize that further ranges of heat treatment temperature and time within the ranges explicitly recited above are contemplated and are within the scope of the present disclosure. Similarly, non-thermal treatments such as blanket UV exposure or exposure to an oxidative plasma such as O2 can be used for similar purposes.

[0037] The throughput of wafers is a substantial limiting factor for implementing EUV lithography in high-volume semiconductor manufacturing, which is directly related to the dose required for patterning a given feature. However, while there are chemical strategies for reducing the imaging dose, in the case of EUV photoresists at <50 nm feature sizes and pitches, a negative correlation is generally observed between the imaging dose required to print the target feature and feature size uniformity (such as LWR), thereby limiting the operability of the final device and wafer yield. The patterning ability can be represented by the dose-to-gel value. The required imaging dose can be evaluated by forming a number of exposed pads with the exposure time varying stepwise between pads to vary the exposure dose. Next, the film can be developed, and the remaining resist thickness of all pads can be evaluated, for example, using spectroscopic ellipsometry. The measured thickness can be normalized against the maximum measured resist thickness and plotted against the logarithm of the exposure dose to form a characteristic curve. The maximum slope of the normalized thickness vs. log dose curve is defined as the photoresist contrast (γ), and the dose value at which the tangent drawn through this point becomes 1 is defined as the photoresist dose-to-gel (Dg). D0 corresponds to the starting dose for the initial increase in the film thickness of a negative resist. Such common parameters used for the characterization of photoresists can be estimated according to Mack, C. (Fundamental Principles of Optical Lithography, John Wiley & Sons, Chichester, U.K; pp271 - 272, 2007, incorporated herein by reference).

Example

[0038] Example 1. Preparation of the precursor (C4H9Sn)4S6 This example shows the synthesis of an n-butyltin sulfide cluster composition.

[0039] Sodium sulfide (17.9 g, 230 mmol, Alfa Aesar, 95%) was added to a round-bottom flask (500 mL) equipped with a magnetic stirrer. Next, THF (150 mL, Aldrich) was added to this flask to dissolve the sodium sulfide. The resulting solution was cooled to -78 °C, and then a solution of n-butyltin trichloride (38.1 g, 135.0 mmol, Aldrich, 95%) in THF (60 mL) was added dropwise thereto. The mixed solution formed a slurry, which was stirred at room temperature for 16 hours and then filtered through a short plug of Celite®. The resulting filtrate was dried under reduced pressure and subsequently dissolved in dichloromethane. The solution was filtered through a silica plug and further eluted with dichloromethane. Removal of the solvent and other volatile components under reduced pressure yielded an amorphous solid, which was triturated with pentane, collected by filtration, and dried under reduced pressure to give (C4H9)4Sn4S6 (21.02 g, 69.5%) as a white amorphous solid.

[0040] Figure 2 shows the 119 Sn{ 1 H} NMR spectrum of (C4H9Sn)4S6 in benzene-d6. This spectrum shows one peak at -144.3 ppm due to the four tin atoms in an equivalent bonding environment. The benzene-d6 solvent had a resonance at -149 MHz.

[0041] Figure 3 shows the 1The \(^1H\) NMR spectrum is shown. This spectrum shows a resonance at -1.63 ppm (\(J = 7.6\) Hz) and a septet at -1.29 ppm (\(J = 7.2\) Hz). The integration ratio is 1:1, and each resonance pattern corresponds to the eight - \(CH_2\) - hydrogens of the butyl ligand. The spectrum shows a triplet at -1.46 ppm (\(J = 7.8\) Hz), which corresponds to the - \(CH_2\) - proton closest to the tin atom, and a triplet at -0.80 ppm (\(J = 7.3\) Hz), which corresponds to the - \(CH_3\) proton. The integration ratio is 1:1.5, corresponding to a total of eight \(\alpha\) - \(CH_2\) - protons and a total of twelve - \(CH_3\) protons. The toluene - \(d_8\) solvent had resonances at -500 MHz.

[0042] Figure 4 shows the \(^{13}C\) NMR spectrum of \((C_4H_9Sn)_4S_6\) in benzene - \(d_6\). 13 The \(^{13}C\) NMR spectrum is shown. This spectrum shows singlets at -29.80 ppm, -27.43 ppm, and -26.13 ppm, corresponding to the - \(CH_2\) - carbons in the butyl ligand, respectively. This spectrum shows a singlet at -13.64 ppm, which corresponds to the - \(CH_3\) carbon. The benzene - \(d_6\) solvent had resonances at -101 MHz.

[0043] This characterization confirmed the synthesis of the purified n - butyltin cluster - composition product R1.

[0044] Example 2: Preparation of the precursor \((C_4H_7Sn)_4S_6\) This example shows the synthesis of an n - butenyltin cluster composition.

[0045] n - Butenyltin trichloride was prepared by reacting 1 part of \((C_4H_7)_4Sn\) with 3 parts of \(SnCl_4\). These procedures were adapted from the method of U.S. Patent No. 2,873,288 and Schumann, Herbert; Aksu, Yilmaz; Wassermann, Birgit C. Journal of Organometallic Chemistry 691(8), 1703 - 1712(2006).

[0046] (C 4 H 7 ) 4 Synthesis of Sn 。A reflux condenser and a nitrogen inlet were attached, and THF (500 mL) was added to a three-necked flask equipped with a large magnetic stir bar and containing freshly cut magnesium turnings (42.8 g, 1.7 mol). The solution was heated to reflux and stirred for 15 minutes. The heat source was removed, and upon addition of a small amount (ca. 5 mL) of 3-butenyl bromide, the mixture refluxed. Further, 3-butenyl bromide (125 g, 0.93 mol) was added dropwise to maintain gentle reflux. After the addition was complete, the resulting 3-butenyl Grignard solution was heated at reflux for 1 hour. The solution was cooled and then stirred at room temperature for 12 hours. Instead, a solution of SnCl4 (5.4 g, 0.22 mol) in THF (400 mL) was carefully prepared by adding SnCl4 dropwise to a cooled (-78 °C) solution of THF. (Note: A large amount of gas evolution, presumably due to the formation of HCl(g) by hydrolysis of SnCl4, can occur when SnCl4 is added to THF). The previously prepared 3-butenyl Grignard solution was added dropwise to the cooled solution of SnCl4. After the addition was complete, the solution was warmed to room temperature and stirred for 12 hours. Next, the solution was concentrated to half its volume and pentane (200 mL) was added. The resulting slurry was filtered through Celite® and concentrated under reduced pressure. The residue was placed on a short plug of silica gel (200 g) and eluted with pentane. Removal of volatiles under reduced pressure gave the desired product (C4H7)4Sn (49 g, 51%) as a colorless liquid and was confirmed by NMR as follows. 119 Sn NMR (186 MHz, chloroform-d) δ -5.64 (s, 1Sn). 1 H NMR (500 MHz, chloroform-d) δ 5.87 (ddt, J = 16.6, 10.1, 6.3 Hz, 4H, Sn-butenyl=CH), 5.01 (dq, J = 17.1, 1.8 Hz, 4H, Sn-butenyl=CH), 4.93 (dq, J = 10.1, 1.5 Hz, 4H, Sn-butenyl=CH), 2.37 - 2.18 (m, 8H, Sn-butenyl-CH2), 1.04 - 0.87 (m, 8H, Sn-butenyl-CH2).

[0047] (C 4 H 7 ) 4 Sn and SnCl 4 Synthesis of n-butenyltin trichloride by reaction of 。(C4H7)4Sn (10 g, 29.5 mmol) was added to a Schlenk flask and dissolved by dropwise addition of toluene (25 ml). SnCl4 (25.13 g, 96.5 mmol) was added dropwise. The resulting mixture was stirred at room temperature for 2 h, then Cl2Pt(PPh3)2 (0.01 g, 0.013 mmol) was added. Next, the mixture was heated at 110 °C for about 12 h until complete conversion to the desired product was shown by Sn NMR spectroscopy. The mixture was cooled to room temperature and filtered through a short plug of silica, which was washed three times with 20 mL portions of toluene. The filtrate was collected and the volatiles were removed under reduced pressure. Distillation of the product gave a colorless oil with a boiling point of 40 - 75 °C and a vapor pressure of 1 - 0.3 torr, which corresponded to the desired product (C4H7)SnCl3 (24.71 g, 88.2 mmol, 68.5% yield) and was confirmed by NMR as follows. 119 Sn NMR (149 MHz, chloroform-d δ 2.71 (s, 1Sn). 119 H NMR (400 MHz, chloroform-d) δ 5.92 (ddt, J = 16.7, 10.1, 6.4 Hz, 1H, Sn-butenyl=CH2), 5.27 (q, J = 1.4 Hz, 1H, Sn-butenyl=CH), 5.25 - 5.20 (m, 1H, Sn-butenyl-CH), 2.67 (qt, J = 6.8, 1.4 Hz, 2H, Sn-butenyl-CH2), 2.45 (t, J = 7.2 Hz, 2H, Sn-butenyl-CH2). 1

[0048] (C H 4 Sn) 7 S 4 S 6 SynthesisSodium sulfide (17.9 g, 230 mmol, Alfa Aesar, 95%) was added to a round-bottom flask (500 mL) equipped with a magnetic stirrer. Next, THF (150 mL) was added to this flask, and the resulting solution was cooled to -78 °C. A solution of (C4H7)SnCl3 (37.8 g, 135.0 mmol) in THF (60 mL) was added dropwise to the cooled sodium sulfide solution described above. The resulting slurry was stirred at room temperature for 16 hours and filtered through a short plug of Celite®. The filtrate was dried under reduced pressure and dissolved in dichloromethane. The resulting solution was filtered through a silica plug. This silica plug was washed with additional dichloromethane, and the resulting dichloromethane solution was mixed with the original filtrate. Removal of the solvent and volatile components under reduced pressure gave an amorphous solid, which was triturated with pentane, collected by filtration, and dried under reduced pressure to give (C4H7Sn)4S6 (18.0 g, 60.1%) as a white solid.

[0049] Figure 5 shows the 119 119Sn NMR spectrum of (C4H7Sn)4S6 in chloroform-d. This spectrum shows one peak corresponding to four tin atoms in an equivalent bonding environment at -141.64 ppm. The chloroform-d solvent had a resonance at -149 MHz.

[0050] Figure 6 shows the 1The ¹H NMR spectrum is shown. This spectrum shows a ddt pattern (J = 16.6, 10.1, 6.3 Hz) at -5.89 ppm corresponding to one of the =CH₂ hydrogens of each of the four butenyl ligands. This spectrum also shows a multiplet at -5.12 to -5.04 ppm corresponding to another =CH₂ hydrogen of each of the four butenyl ligands. This spectrum shows a quartet (J = 1.6 Hz) at -5.15 ppm corresponding to the four =CH hydrogens. This spectrum shows a multiplet and a triplet (J = 7.8 Hz) at -2.79 to -2.32 ppm where each pattern corresponds to eight -CH₂- hydrogens and shows an integration of 1:1. The chloroform-d solvent had a resonance at -400 MHz.

[0051] Figure 7 shows the 13 ¹³C NMR spectrum of (C₄H₇Sn)₄S₆ in benzene-d₆. This spectrum shows a singlet at -138.40 ppm corresponding to the =CH carbon of the butenyl ligand. The singlet at -116.05 ppm corresponds to the =CH₂ carbon. The singlets at -29.02 ppm and -28.70 ppm correspond to the bonding environments of the two -CH₂- carbons. The benzene-d₆ solvent had a resonance at -101 MHz.

[0052] This characterization confirmed the synthesis of the purified n-butenyltin cluster composition product R₂.

[0053] Example 3. Preparation of Precursor Solutions of (C₄H₉Sn)₄S₆ and (C₄H₇Sn)₄S₆ This example shows the preparation of precursor solutions having either an n-butyltin cluster composition or an n-butenyltin cluster composition. These solutions were prepared using one of six solvents and a range of tin concentrations.

[0054] A photoresist precursor solution was prepared by adding 0.17 g of (C₄H₉Sn)₄S₆ of Example 1 to 20 mL of toluene. This mixture was gently heated to form a visually clear, transparent, stable, and homogeneous solution. Diagnosis 1 H and119 Sn NMR resonance indicates that this solution contains the tetramer (n-butylSn)4S6. Further toluene solutions with tin concentrations of 64 - 288 mM were readily prepared by this method. Solutions using the solvents THF, chlorobenzene, 1,1,2-trichloroethane, perfluorobenzene and pentafluorobenzene were also prepared in a similar manner. The tin concentrations in these solutions range from 1 - 150 mM.

[0055] A photoresist precursor solution was prepared by adding 0.17 g of (C4H7Sn)4S6 of Example 2 to 20 mL of toluene. This mixture was gently heated to form a clear solution. Throughout all periods of the film deposition described above, the solution remained clear. Diagnosis 1 H and 119 Sn NMR resonance indicates that this solution contains the tetramer (n-butenylSn)4S6. Further toluene solutions with tin concentrations of 64 - 288 mM were readily prepared by this method. Solutions using the solvents THF, chlorobenzene, 1,1,2-trichloroethane, perfluorobenzene and pentafluorobenzene were also prepared in a similar manner. The tin concentrations in these solutions range from 1 - 150 mM.

[0056] Example 4. Wafer Coated with a Film This example shows the production of a wafer coated with a film, demonstrating that thin and smooth films can be deposited with cluster compositions of both n-butyltin and n-butenyltin.

[0057] A silicon wafer (10.2 cm in diameter) having a natural oxide surface was used as a substrate for thin film deposition. Unless otherwise indicated, a toluene-based precursor solution prepared as described in Example 3 was spin-coated onto the untreated wafer at 1500 rpm for 30 seconds to deposit a film on the untreated wafer. In some cases, the wafer was pretreated by wetting it with a casting solvent if it was useful to obtain a good coating. In particular, a precursor solution of (C4H9Sn)4S6(R1) in toluene having a tin concentration of 75 mM was spin-coated onto the wafer at 1500 rpm for 30 seconds to produce a film sample (F1) having a film thickness of 176 nm. A second precursor solution of (C4H7Sn)4S6(R2) in toluene having a tin concentration of 75 mM was spin-coated onto the wafer at 1500 rpm for 30 seconds to produce a film sample having a film sample (F2) with a thickness of 188 nm. Figure 8 shows curve a of the FTIR spectrum of the powder of R1 and curve b of the FTIR spectrum of the film sample F1. The results show that the characteristic alkane C-H stretching absorption at 3000~2850 cm -1 and the deformation angle absorption at 1470~1450 cm-1 are maintained. However, the film shows different absorption in the range of 1600~500 cm -1 , suggesting a spatial change in the structure of the Sn-S cage. Figure 9 shows curve a of the FTIR spectrum of the powder of R2 and curve b of the FTIR spectrum of the film sample F2. These results show that the characteristic alkane and alkene C-H stretching absorptions at 3100~2850 cm -1 are maintained.

[0058] The wafer coated with a 23.68 nm thick film of (C4H9Sn)4S6 showed a root mean square surface roughness of 0.7 nm as measured by atomic force microscopy. Similarly, the wafer coated with a 21.1 nm thick film of (C4H7Sn)4S6 showed a surface roughness of 0.4 nm. These results show that a tin cluster composition can be deposited as a relatively smooth film.

[0059] Precursor solutions of toluene and (C4H9Sn)4S6 cluster compositions at various concentrations were used to fabricate sets of film samples. Figure 10 shows the linear dependence of film thickness on the concentration of R1. Precursor solutions of toluene and (C4H7Sn)4S6 cluster compositions at various concentrations were used to fabricate a second set of film samples. Figure 11 shows the linear dependence of film thickness on the concentration of R2. These results indicate that tin cluster compositions can be deposited with a well-controlled thickness on the nanometer scale.

[0060] Example 5. Negative Image Formation Using UV Exposure This example shows that UV radiation can induce negative dissolution contrast in films made from cluster compositions of n-butyltin and n-butenyltin.

[0061] The film samples F1 and F2 prepared as described in Example 4 were placed in a box lined with aluminum foil in a glove box filled with argon. The compartments of the film samples F1 and F2 were exposed to laboratory UV light, and radiation with a wavelength of approximately 354 nm was uniformly supplied to all samples for several minutes to obtain an appropriate dose, yielding film samples F1 and F2 with exposed and unexposed regions of the film. Next, the film samples were developed by immersing them in a mixture of anisole and THF for 30 seconds. For each anisole:THF mixture, the film thicknesses of the exposed and unexposed compartments of each film sample were measured using a J.A.Woollam M-2000 spectroscopic ellipsometer. The normalized film thickness was calculated by dividing the thickness of the developed compartment by the average thickness of the film before the development step.

[0062] Figure 12 shows the normalized film thickness of the unexposed section of film F1 as a function of the volume fraction of anisole in THF. This plot shows that the unexposed film of (C4H9Sn)4S6 completely dissolves in each developer composition after 30 seconds. Figure 13 shows the normalized film thickness of the UV-exposed section of film F1 as a function of the volume fraction of anisole in THF. This plot shows that more than 70% of the film thickness is maintained after 30 seconds of development. These data indicate that a change in the dissolution rate occurs after UV exposure, that is, a chemical change is induced by UV exposure and a latent image is formed.

[0063] Figure 14 shows the normalized film thickness of the unexposed section of film F2 as a function of the volume fraction of anisole in THF. This plot shows that the unexposed film of (C4H7Sn)4S6 dissolves in anisole in THF from 0 to 40%. In anisole from 60 to 100 volume%, the dissolution of the unexposed R2 composition decreases with an increase in the volume percentage of anisole. Figure 15 shows the normalized film thickness of the UV-exposed section of film F2 as a function of the volume fraction of anisole in THF. This plot shows that the exposed film of (C4H7Sn)4S6 maintains 97 - 99% of its original thickness in all developer compositions tested.

[0064] All of these data indicate that chemical changes that alter the dissolution rate occur upon UV exposure of the films of (C4H9Sn)4S6 and (C4H7Sn)4S6. Exposure and subsequent dissolution in a mixed solution of anisole and THF reveal that these films are negative photoresists.

[0065] Example 6. Solubility Contrast by EUV Exposure This example shows the solubility contrast of the film of Example 3 after exposure to EUV radiation.

[0066] On a silicon wafer with a diameter of 10.2 cm having a natural oxide surface, a film was deposited as described in Example 4. Precursor solutions of (C4H9Sn)4S6 and (C4H7Sn)4S6 were prepared at appropriate concentrations for the deposition of the R1 and R2 films, each with a thickness of approximately 20 nm. In the contrast curves shown in FIGS. 16 and 17, the film thickness was in the range of 20.6 nm to 22.9 nm.

[0067] The film was exposed on an EUV Direct Contrast Tool at Lawrence Berkeley National Laboratory. Before exposure, the film was baked at 100 °C for 2 minutes. A linear array of 50 circular exposure regions with a diameter of approximately 500 μm was projected onto the wafer using increasing UV exposure doses. After exposure, the film was developed with 2-heptanone, THF, a 20% (v / v) mixture of anisole in THF, or a 40% (v / v) mixture of anisole in THF. The film was developed either with or without a post-exposure bake at 100 °C for 2 minutes. The thickness of each exposed pad was evaluated with a J.A.Woollam M-2000 spectroscopic ellipsometer. The normalized thickness of each pad as a function of EUV dose is plotted in FIGS. 16 and 17 for various process conditions (curves a - k). In the unexposed and low-dose regions, the normalized film thickness is approximately 0. When each film shows the combined effect of exposure dose and developer composition on solubility contrast, the curve rises to a maximum value (dose-to-gel, D -2 exceeding 7 mJ / cm g ).

[0068] Table 1 summarizes the process conditions, developer composition, and induced results (D o , Dg, and contrast) for each composition, (C4H9Sn)4S6 (R1) and (C4H7Sn)4S6 (R2). Curves a - k are shown in FIGS. 16 and 17.

[0069]

Table 1

[0070] The results show that EUV exposure of the films of (C4H9Sn)4S6 and (C4H7Sn)4S6 causes chemical changes that alter the dissolution rate. The exposure and subsequent processing demonstrate that good solubility contrast can be achieved for compositions R1 and R2. Under the tested process conditions, the maximum contrast was achieved by developing in THF after the bake step. Without the bake step, for the R1 composition, better contrast was obtained with 20% (v / v) anisole in THF than with THF. For the R2 composition without the bake step, better contrast was obtained with a THF developer.

[0071] The above embodiments are intended to be illustrative and not limiting. Further embodiments are within the scope of the claims. Additionally, while the invention has been described with reference to specific embodiments, those skilled in the art will recognize that modifications in form and detail can be made without departing from the spirit and scope of the invention. Any incorporation by reference of the above documents is limited so that no subject matter contrary to the disclosed disclosure is incorporated. Within the scope described herein for a particular structure, composition, and / or process with components, elements, ingredients, or other divisions, unless specifically stated otherwise, the disclosure can include embodiments that include the particular embodiments, the particular components, elements, ingredients, other divisions, or combinations thereof described above, as well as further features that do not change the basic nature of the subject matter as suggested in the discussion. It should be understood to include embodiments that consist essentially of such particular components, ingredients, or other divisions, or combinations thereof. It should be confirmatively stated that the present invention described above includes the following aspects. First aspect: A structure having a radiation-sensitive pattern-forming layer including a substrate and a radiation-sensitive layer containing an organotin cluster represented by the formula (RSn) 4 X 6 (wherein R is an organic ligand having 1 to 15 carbon atoms bonded to Sn by a metal-carbon bond, and X is S or Se), and the radiation-sensitive layer has an average thickness of about 2 nm to about 1 micron. Second aspect: The structure according to the first aspect, wherein R is an alkyl group, an alkenyl group, an aryl group, or a combination thereof. Third aspect: The structure according to the first aspect, wherein the organotin cluster includes n-butyltin sulfide, n-butenyltin sulfide, or a combination thereof. Fourth aspect: The structure according to any one of the first to third aspects, wherein the radiation-sensitive layer has an average thickness of 2 nm to 200 nm. Fifth aspect: The structure according to any one of the first to fourth aspects, wherein the thickness of the layer at any location across the structure varies by 25% or less from the average thickness of the layer. Sixth aspect: The structure according to any one of the first to fifth aspects, wherein the radiation-sensitive pattern-forming layer includes a material having a virtual image corresponding to a selected pattern of radiation, and the virtual image has regions having different solubilities in an organic solvent. Seventh aspect: The structure according to any one of the first to sixth aspects, wherein the radiation-sensitive layer includes a patterned layer including a radiation-irradiated material having low solubility in an organic solvent. Eighth aspect: The structure according to any one of the first to seventh aspects, wherein the radiation-irradiated coating material includes a crosslinked organotin cluster. Ninth aspect: The structure according to any one of the first to eighth aspects, wherein the substrate includes a silicon wafer. Tenth aspect: A pattern-forming precursor solution, an organic solvent, and the formula (RSn) 4 X 6 (Here, R is an organic ligand bonded to Sn by a metal-carbon bond, and X is S or Se) and an organotin cluster composition represented by A pattern-forming precursor solution containing the above and having a concentration of about 0.0005 M to about 1 M based on tin. Aspect 11: The pattern-forming precursor solution according to Aspect 10, having a concentration of about 0.0025 M to about 0.4 M based on tin. Aspect 12: The pattern-forming precursor solution according to Aspect 10 or 11, wherein the organotin cluster composition contains n-butyltin sulfide, n-butenyltin sulfide, or a combination thereof. Aspect 13: The pattern-forming precursor solution according to any one of Aspects 10 to 12, wherein the organic solvent contains benzene, toluene, 1,1,2-trichloroethane, chloroform, tetrahydrofuran (THF), anisole, their derivatives, or a combination thereof. Aspect 14: A method for forming a radiation-sensitive layer suitable for pattern formation on a substrate surface, (RSn) 4 X 6 Depositing clusters on the substrate, where X is S or Se, and R is a hydrocarbyl group (or organic ligand) bonded to Sn by a metal-carbon bond, the depositing including, and the depositing 1) Contacting a solution containing (RSn) 4 S 6 clusters and an organic solvent with the substrate surface, and Removing the solvent to form a radiation-sensitive coating material, 2) Volatilizing the (RSn) 4 X 6 clusters, and Collecting the volatilized clusters on the substrate surface, or 3) Using the vapor of (RSn) 4 Y 6 (where Y is a halogen atom) and the gas H 2 X to perform reactive deposition of (RSn) 4 X 6 including, the method. Aspect 15: The method according to Aspect 14, wherein the organic solvent contains benzene, toluene, 1,1,2-trichloroethane, chloroform, tetrahydrofuran (THF), anisole, their derivatives, or a combination thereof. Aspect 16: The method according to Aspect 14, wherein the depositing includes vapor deposition or spin coating. Aspect 17: The method according to Aspect 14, wherein the depositing includes disposing a solution, and the solution has a concentration of tin atoms of about 0.0005 M to about 1 M. ​ Aspect 18: A method of forming a coated pattern, comprising developing a pattern from a virtual image formed by exposing a radiation-sensitive layer to a radiation pattern to form an irradiated layer, wherein the developing of the pattern comprises contacting the irradiated layer with an organic solvent to substantially remove a non-irradiated portion of the irradiated layer, the radiation-sensitive layer being formed using an organic tin cluster, and the irradiation of the radiation-sensitive layer resulting in a material having substantially lower solubility in the organic solvent. Aspect 19: The method according to aspect 18, wherein the radiation pattern comprises a pattern of UV or EUV radiation. Aspect 20: The method according to aspect 19, wherein the EUV radiation has a dose of about 1 mJ / cm 2 to about 175 mJ / cm 2 . Aspect 21: The method according to any one of aspects 18 to 20, wherein the organic solvent comprises ethyl lactate, an ether such as tetrahydrofuran (THF), dioxane or anisole, a ketone such as 2-pentanone, 3-pentanone, hexanone, 2-heptanone or octanone, or a combination thereof. Aspect 22: The method according to any one of aspects 18 to 21, wherein the contacting with the organic solvent is carried out over a period of about 5 seconds to about 30 minutes.

Claims

1. A substrate and an EUV radiation-sensitive layer formed from an organotin cluster represented by the formula (RSn) ４ ４ X ６ (wherein R is an organic ligand having 1 to 15 carbon atoms bonded to Sn by a metal-carbon bond, selected from the group consisting of an alkyl group, an alkenyl group, an aryl group, and combinations thereof, and X is S or Se), the radiation-sensitive pattern-forming layer having a structure including the EUV radiation-sensitive layer having an average thickness of 2 nm to 1 micron.

2. The organic tin cluster contains tin n-butyl sulfide, tin n-butenyl sulfide or a combination thereof, and the structure according to claim 1.

3. The EUV radiation-sensitive layer has an average thickness of 2 nm to 200 nm, and the structure according to claim 1 or 2.

4. The thickness of the layer at any location across the structure varies by 25% or less from the average thickness of the layer, and the structure according to any one of claims 1 to 3.

5. The radiation-sensitive pattern-forming layer contains a material having a virtual image corresponding to a selected pattern of radiation, and the virtual image has regions having different solubilities in an organic solvent, and the structure according to any one of claims 1 to 4.

6. A negative image can be formed by developing the virtual image with the organic solvent, and the structure according to claim 5.

7. The radiation-sensitive pattern-forming layer contains a non-radiation-irradiated coating material and a radiation-irradiated coating material, and the radiation-irradiated coating material contains a crosslinked organic tin cluster, and X is S, and the structure according to any one of claims 1 to 6.

8. The substrate includes a silicon wafer, and the structure according to any one of claims 1 to 7.

9. The EUV radiation-sensitive layer is sensitive to EUV irradiation at a dose of 1 mJ / cm ２ to 175 mJ / cm ２ The structure according to claim 1.

10. A method of forming a coating pattern, comprising developing a pattern from a virtual image formed by exposing a radiation-sensitive layer to a radiation pattern including EUV radiation to form a radiation-exposed layer, wherein said developing of said pattern comprises contacting said radiation-exposed layer with an organic solvent to substantially remove a non-radiation-exposed portion of said radiation-exposed layer, said radiation-sensitive layer being formed using an organotin cluster, said organotin cluster being represented by the formula (RSn) ４ X ６ wherein R is an organic ligand bonded to Sn by a metal-carbon bond, selected from the group consisting of an alkyl group, an alkenyl group, an aryl group and combinations thereof, and X is S or Se), and wherein irradiation of said radiation-sensitive layer results in a material that is substantially less soluble in an organic solvent.

11. The EUV radiation has a dose of 1 mJ / cm ２ to 175 mJ / cm ２ The method according to claim 10, having a dose of

12. The organic solvent contains ethyl lactate, ether, ketone or a combination thereof, and the method according to claim 10 or 11.

13. Contacting with the organic solvent is performed over 5 seconds to 30 minutes, and the method according to any one of claims 10 to 12.

14. Before development, further including forming the radiation-irradiated layer by irradiating the radiation-sensitive layer with EUV radiation along a selected pattern, and the method according to any one of claims 10 to 13.

Images