Organometallic metal chalcogenide clusters and their applications in lithography
Organotin clusters in organic solvents form a radiation-sensitive coating that addresses the challenge of high-resolution EUV lithography by providing improved pattern formation and etching contrast, suitable for advanced semiconductor manufacturing.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- INPRIA CORP
- Filing Date
- 2026-03-17
- Publication Date
- 2026-06-23
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Figure 2026102781000002 
Figure 2026102781000003 
Figure 2026102781000004
Abstract
Description
[Technical Field]
[0001] Cross-reference of related applications This application claims priority to Cardineau et al.'s concurrently pending U.S. Provisional Patent Application No. 62 / 876,842, filed on 22 July 2019, 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 for forming photoresist coatings and patterns using these compositions. [Background technology]
[0003] In semiconductor manufacturing, material patterns are formed to manufacture devices and circuits. These patterned structures are generally formed by repeating photolithography processes consisting of thin-film deposition, radiation exposure, and etching steps, in order to form a large number of devices in a small area. Technological advancements can lead to increased device density, which is desirable for improved performance.
[0004] Thin film coatings of organic and organometallic compositions can be used as radiation-sensitive photoresists. Radiation can alter the chemical structure and composition of the photoresist, thereby affecting its dissolution rate in a selected solvent. The radiation pattern can be replicated as a latent image within 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 layer, by an etching process. [Overview of the project] [Problems that the invention aims to solve]
[0005] Liquid developers can be particularly effective for developing latent images in photoresists. 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 is formed when completely removed. This process is repeated many times to form further layers of the patterned material. In semiconductor manufacturing, EUV lithography has been introduced to obtain very small features and device sizes for improved circuit functionality. This type of lithography has created a need for a new type of photoresist that effectively absorbs radiation with a wavelength of 13.5 nm. [Means for solving the problem]
[0006] In a first aspect, the present invention relates to a formulation of (RSn)4X6 (where R is an organic group or a hydrocarbyl group, and X is S or Se) in an organic solvent that can form a continuous and smooth photoresist coating. The formulation may 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), the precursor solution having 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 (RSn)4X6 radiosensitive film having an average thickness of 1 micron or less and a thickness variation of 25% or less from the average at any point across the film. The coating comprises a metal sulfide (selenide) network having metal cations with organic ligands via metal-carbon bonds, or a metal-sulfide-oxide-hydroxide network having metal cations bonded to organic ligands via metal-carbon bonds. In some embodiments, this aspect may be described as a structure having a radiosensitive pattern-forming layer comprising a substrate and a radiosensitive layer comprising an organotin cluster represented by the formula (RSn)4X6 (wherein R is an organic ligand having 1 to 15 carbon atoms bonded to Sn by metal-carbon bonds, and X is S or Se), the radiosensitive layer having 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, the method 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, the method 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, the method 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 the 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 the Drawings
[0010] [Figure 1] Schematic diagram of the (C4H9Sn)4S6 cluster. [Figure 2] 119Sn{1H} NMR spectrum of (C4H9Sn)4S6 in benzene-d6. [Figure 3] 1H NMR spectrum of (C4H9Sn)4S6 in toluene-d8. [Figure 4] 13C NMR spectrum of (C4H9Sn)4S6 in benzene-d6. [Figure 5] 119Sn{1H} NMR spectrum of (C4H7Sn)4S6 in chloroform-d. [Figure 6] 1H NMR spectrum of (C4H7Sn)4S6 in chloroform-d. [Figure 7] 13C NMR spectrum of (C4H7Sn)4S6 in benzene-d6. [Figure 8] Stacked FTIR spectra of R1 in solid (ATR-FTIR) (a) and on Si wafer (Mapper-FTIR) (b). [Figure 9] Stacked FTIR spectra of R2 in solid (ATR-FTIR) (a) and on Si wafer (Mapper-FTIR) (b). [Figure 10] Plot of film thickness against the concentration of (C4H9Sn)4S6 in the precursor solution. The solvent is toluene. [Figure 11] Plot of film thickness against the concentration of (C4H7Sn)4S6. The solvent is toluene. [Figure 12] Plot of the normalized film thickness as a function of the developer composition for the unexposed film of R1 immersed in the developer composition for 30 seconds. [Figure 13]This is a plot of the normalized film thickness as a function of the developer composition of a UV-exposed film R1 immersed in a developer composition for 30 seconds. [Figure 14] This is a plot of the normalized film thickness as a function of developer composition for an unexposed R2 film immersed in a developer composition for 30 seconds. [Figure 15] This is a plot of the normalized film thickness as a function of developer composition for a UV-exposed film of R2 immersed in a developer composition for 30 seconds. [Figure 16] This is a plot of contrast curves obtained using the R1 formulation and various process conditions. [Figure 17] This is a set of contrast curves obtained using R2 formulations and various process conditions. [Modes for carrying out the invention]
[0011] Organotin clusters provide improved properties in high-resolution radiation-based patterning, and the tin tetramers described herein are suitable for use in EUV lithography. Clusters are formed as tetramer species having crosslinkable thio groups and associated alkyl groups to achieve cluster stability. The tin tetramers, which are amorphous solids at room temperature, are soluble in suitable organic liquids. Patterning formulations are described based on the dissolution of the tin tetramers in organic solvents and the deposition of uniform and functional coatings on suitable substrates. EUV patterning with desirable properties is demonstrated.
[0012] The manufacturing of semiconductor circuits and devices involves a periodic decrease in critical dimensions across each successive generation. As these dimensions decrease, new materials and methods may be required to meet the demands for processing and patterning smaller feature sizes. Patterning generally involves the selective exposure of thin layers of radiosensitive 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, providing a particularly suitable new type of material for obtaining very high etching contrast at the same time.
[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 the case of extreme ultraviolet patterning. Alkyl metal patterning compositions are described, for example, in U.S. Patent No. 9,310,684, 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, entitled "Organometallic Solution Based High Resolution Patterning Compositions and Corresponding Methods," and U.S. Patent No. 10,228,618 B1, entitled "Organotin Oxide Hydroxide Patterning Compositions, Precursors, and Patterning," both incorporated herein by reference. The organotin clusters described herein involve substitution of the oxohydroxo ligand with a sulfide ligand, and the results herein demonstrate that the sulfide composition may similarly provide desirable patterning results in EUV pattern formation.
[0014] One of the desirable organometallic precursor solutions for high-resolution EUV lithography exhibits a shelf life that facilitates product distribution, adheres to preferred substrates, results in a uniform and smooth thin-film coating, and responds sensitively to radiation exposure. Desired compositions of these solutions may include a metal sulfide of the (RSn)4S6 type organometallic sulfide dissolved in an organic solvent, where R is a hydrocarbyl ligand having 1 to 15 carbon atoms bonded to tin via a Sn-C bond. In embodiments of particular interest, the organotin sulfide may be dissolved in a polar solvent such as tetrahydrofuran (THF) or a combination of THF and anisole, which serves as a vehicle for uniform coating on the substrate by spin coating and related methods. In further embodiments, these coatings may be exposed to a pattern of UV or EUV light to induce a chemical change in which the exposed areas are more resistant to dissolution in the organic developer than the unexposed areas. This behavior, where the exposed photoresist remains on the substrate after development, characterizes the 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. GACosta, MCSilva, GMde Lima, RMLogo, MTC 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, HWRoesky, Synthesis of (RSn)4X6adamantanes(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, JPEussner, A. Beyer, SWKoch, K. Volz, S. Dehnen, S. Chatterjee, A highly directional molecular white-light emitter driven by a continuous-wave efficient laser diode. Science 352, 1301-1304 (2016).
[0016] The (RSn)4(S,Se)6 cluster has 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 cleavage, which can induce different dissolution rates and allow for desired radiation-based patterning. Alternatively, the R group may contain an unsaturated alkenyl moiety that can be crosslinked by radiation exposure. Both the initial bond cleavage and crosslinking processes are expected to form a negative lithographic pattern based on the change in solubility of the irradiated material. Non-aqueous solutions formed using the cluster yield promising coating compositions with improved precursor solubility, coating quality, and sensitivity compared to other radiation-based organometallic patterning materials.
[0017] Cluster synthesis and formation of coating solution (RSn)4S6 compositions can be prepared by the direct reaction of monoorganotin trichloride in THF with sodium sulfide. Examples describe the synthesis of derivatives where R = butyl and butenyl. The following reaction: 4RSnCl3 + 6Na2S = (RSn)4S6 + 12NaCl The reagents are mixed in a stoichiometric ratio of 4:6. The solution of RSnCl3 in THF is added to a cooled solution of Na2S in THF (-78°C) and reacted. Hydrogen sulfide (H2S) can be used instead of sodium sulfide. The precipitated solid NaCl is removed by filtration. A similar reaction can be carried out using Na2Se to form the selenide cluster compound (RSn)4Se6, and the following discussion can be adapted to and clearly disclosed in correspondence with selenides, as can be said with regard to the discussion of sulfides. Next, the solvent is evaporated to obtain 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 obtain the purified compound, which can be ground under pentane and recovered by filtration to obtain a free-flowing white solid. The following examples show the synthesis for the case of R=n-butyl (C4H9) or R=n-butenyl (C4H7). Some monoorganotintrichloro precursor compounds are commercially available, while others can be synthesized using available protocols, one example of which is discussed in the examples.
[0018] The R (organic) group can be a hydrocarbyl group such as a linear, branched (i.e., secondary or tertiary in a metal bonded to a carbon atom), or cyclic hydrocarbyl group. Each R group individually 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, and includes, for example, methyl, ethyl, propyl, butyl, and branched alkyl groups. In particular, R 1 R 2 R 3 CSnX3(here, 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 by (being 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 (R 1 and R 2 being methyl and R 3 being hydrogen), tert-butyl (R 1 , R 2 and R 3 being methyl), tert-amyl (R 1 and R 2 being methyl and R 3 being -CHCH3), sec-butyl (R 1 being methyl, R 2 being -CHCH3 and R 3 being 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, nThe R group is a cycloalkyl group (cyclopropyl, cyclobutyl, cyclopentyl), an olefin (alkenyl, aryl, allyl), or an alkynyl group, or a combination thereof. In further embodiments, suitable R groups include hydrocarbur groups substituted with heteroatom functional groups, such as cyano, thio, silyl, ether, keto, ester, or halogenated groups, or combinations 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 cluster is generally soluble in a wide range of organic solvents. It can be dissolved in organic solvents such as benzene, toluene, chlorotoluene, 1,1,2-trichloroethane, tetrahydrofuran (THF), anisole, and THF-anisole mixtures, or mixtures thereof. Generally, the choice of organic solvent may depend on solubility parameters, volatility, flammability, toxicity, viscosity, and chemical interaction with the substrate. In particular, THF and THF-anisole mixtures enable the deposition of a smooth and uniform (RSn)4S6 coating. As a photoresist in the case of radiation-based patterning, the precursor solution can generally contain about 0.0005 M to about 1.0 M of tin atoms, in further embodiments about 0.00025 M to about 0.6 M of tin atoms, and in further embodiments about 0.01 M to about 0.40 M of tin atoms. This solution can be applied to a substrate by spin coating or other suitable techniques. Those skilled in the art will recognize that further ranges of concentrations within the explicitly stated range above can be considered and fall within the scope of this disclosure. Generally, the precursor solution can be thoroughly mixed using a suitable mixing apparatus to form that amount of material. Contaminants, small particles, and other components that do not dissolve properly can be removed using appropriate filtration.
[0020] A coating material can be formed by depositing a precursor solution onto a selected substrate and performing subsequent processing. The substrate generally provides a surface on which a coating material can be deposited, and the substrate may contain multiple layers within its surface, related to the top layer. A suitable substrate surface can contain any suitable material. Some substrates of particular interest include, across the substrate surface and / or within layers of the substrate, inorganic materials such as silicon wafers, silica substrates, and other ceramics, organic polymers, composites thereof, and combinations thereof. While wafers such as relatively thin cylindrical structures may be advantageous, any suitable molded structure can be used. Polymer substrates or substrates having polymer layers on non-polymer structures may be desirable for specific applications based on lithography performance or substrate cost and flexibility, and suitable polymers can be selected based on the relatively low processing temperature that can be used for processing the patternable materials described herein. Suitable polymers include, for example, polycarbonates, polyimides, polyesters, polyalkenes, copolymers thereof, or mixtures thereof. Generally, especially for high-resolution applications, it is desirable for the substrate to have a flat surface. However, in certain embodiments, for specific patterning applications, the substrate may have substantial topography in which features are intended to be filled or planarized by a resist coating.
[0021] A coating is formed. Generally, precursors can be supplied to a substrate using any suitable solution or gas-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 methods such as deposition of volatile compounds, 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, but currently, the resolution obtained by printing and the like is much lower than the resolution obtained by radiation-based pattern formation as described herein. The thickness of the resulting deposited layer can be adjusted by adjusting the solution concentration using coating parameters. 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 the substrate, although this uniformity can be compromised by the formation of beads near the edges of the substrate. In some embodiments, the substrate can be rotated at speeds of about 500 rpm to about 10,000 rpm, in further embodiments about 1,000 rpm to about 7,500 rpm, and in even further embodiments about 2,000 rpm to about 6,000 rpm. The rotation speed can be adjusted to obtain the desired coating thickness. Spin coating can be performed in a time of about 5 seconds to about 5 minutes, 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 initially spread the entire composition across the substrate. Edge beads can be removed by backside rinsing, edge bead removal steps, etc., using a suitable organic solvent. Those skilled in the art will recognize that further ranges of spin coating parameters within the expressed range will be considered and that they will fall within the scope of this disclosure. The cleaning of bead edges of organometallic patterning materials is described in U.S. Patent No. 10,627,719, entitled “Methods Of Reducing Metal Residue In Edge Bead Region From Metal-Containing Resists,” granted to Waller et al., which is incorporated herein by reference.
[0023] With respect to vapor-based deposition, several compounds can be heated in an inert atmosphere to achieve a suitable vapor pressure for forming a desired thin coating. The substrate surface can be positioned in a suitable close proximity to receive the vapor of the compound. Heating for forming volatile compounds can exceed 400°C, and in some embodiments, may be between 450°C and 1000°C. Those skilled in the art will recognize that further ranges of temperatures within the explicitly stated range above can be considered and that they fall within the scope of this disclosure. Alternatively or in addition, deposition can be carried out using chemical vapor deposition or atomic layer deposition. Atomic layer deposition is essentially stepwise CVD deposition in which a layer of organotin trihalide is deposited, then reacted with hydrogen sulfide (or selenide) gas, and then this is repeated to obtain the desired coating thickness. These reactive deposition methods can be achieved using the vapor of organotin trihalide together with gaseous hydrogen sulfide (or selenide). These deposition methods can be carried out in a suitable CVD reaction chamber, etc.
[0024] The coating process itself can lead to the evaporation of some of the solvent and / or the movement of the solution that stimulates evaporation, as many coating processes form droplets or other forms of the coating material over a larger surface area. As the solvent decreases, the concentration of chemical species in the material increases, and therefore the viscosity of the coating material tends to increase. One objective during the coating process may be to remove enough solvent to stabilize the coating material for further processing. During coating or subsequent heating, the coating species can react with air, hydrolyze, or condense to form a chemically modified coating material.
[0025] To select effective processing conditions for the pattern formation process, empirical evaluation of the properties of the resulting coating material can generally be performed. While heating may not be necessary for the process to function without problems, heating the coated substrate may be desirable to accelerate the process, / or improve process reproducibility, and / or promote the vaporization of volatile by-products. In embodiments where heat is applied to evaporate the solvent during pre-exposure baking, 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. Heating to remove the solvent can generally be performed for at least about 0.1 minutes, in further embodiments, about 0.5 minutes to about 30 minutes, and in further embodiments, about 0.75 minutes 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 film thickness and precursor concentration is shown. Those skilled in the art will recognize that further ranges of heating temperatures and times within the explicitly stated ranges above will be considered and will fall within the scope of this disclosure. As a result of 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 rates.
[0026] The deposition process determines the thickness of the undried coating. For further processing, the solvent is generally removed, leaving a solid layer as a coating on the substrate. The solution concentration and process conditions affect the dry coating thickness, and selecting these allows for the achievement of desired pattern formation characteristics. The average dry coating thickness can be approximately 2 nm to 1000 nm, in further embodiments approximately 3 nm to 300 nm, and in even further embodiments approximately 3 nm to 80 nm. In the case of deposition described later, the coating thickness can be adjusted accordingly by process conditions to achieve the desired layer thickness of the coating. Those skilled in the art will recognize that further average thickness ranges within the explicitly stated ranges above are considered and fall within the scope of this disclosure.
[0027] Pattern formation After drying and possible hydrolysis, fine patterns can be formed on the coating material using radiation. As mentioned above, the composition of the precursor solution and, consequently, the composition of the corresponding coating material can be planned so that the desired form of radiation (EUV radiation of particular interest) is sufficiently absorbed. The absorption of radiation provides enough energy to break the bonds between the metal and the alkyl ligands, thereby preventing at least some of the alkyl ligands from being used to stabilize the material so that tin sulfide / selenide can be formed. Instead, the absorption of high-energy radiation can initiate a coupling (polymerization) reaction between the unsaturated centers in the R ligands bonded to adjacent tin sulfide / selenide clusters. Although the radiation-induced modification may not be very clear in the case of alkyltin ligands in sulfide clusters, the composition is found to provide good pattern-forming properties. Radiolysis products, such as alkyl ligands or other fragments, may or may not diffuse from the film, depending on the process variables and the nature of such products. Upon absorbing a sufficient amount of radiation, the exposed coating material condenses, i.e., forms a network with increased crosslinking, which may contain further water absorbed from the ambient atmosphere. Radiation can generally be supplied by a selected pattern. The radiation pattern is transferred to the coating material in corresponding patterns or latent images of irradiated and unirradiated areas. The irradiated areas contain chemically altered coating material, while the unirradiated areas generally contain the as-formed coating material. The coating material can be developed to remove the unirradiated coating material or selectively remove the irradiated coating material to form very smooth edges.
[0028] Radiation can generally be directed onto a coated substrate via a mask, or the radiation beam can be controlledly scanned across the substrate. Generally, the radiation can include electromagnetic radiation, electron beams (beta rays), or other suitable radiation. Generally, electromagnetic radiation can have a desired wavelength or wavelength range, such as visible rays, ultraviolet rays, extreme ultraviolet rays, 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. Therefore, it may be desirable to use ultraviolet, extreme ultraviolet, or X-ray radiation or electron beam irradiation, especially to achieve high resolution patterns.
[0029] According to the international standard ISO 21348 (2007), incorporated herein by reference, ultraviolet light extends to wavelengths between 100 nm and less than 400 nm. Krypton fluoride lasers can be used as a light source for 248 nm ultraviolet light. The ultraviolet range can be further subdivided in several ways based on approved standards, including extreme ultraviolet (EUV) from 10 nm to less than 121 nm and far ultraviolet (FUV) from 122 nm to less than 200 nm. The 193 nm light from argon fluoride lasers can be used as a radiation source for FUV. 13.5 nm EUV light is used in lithography and is generated from Xe or Sn plasma sources excited using high-energy lasers or discharge pulses. Soft X-rays can be defined as wavelengths between 0.1 nm and less than 10 nm.
[0030] The amount of electromagnetic radiation can be characterized by its fluence or dose, which is defined by the radiation flux integrated over the exposure time. Generally, a suitable EUV radiation 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. Those skilled in the art will recognize that further ranges of radiation fluence within the explicitly stated range above will be considered and that they fall within the scope of this disclosure.
[0031] Based on the design of the coating material, a high contrast in material properties can be induced between the irradiated and unirradiated areas of the coating material. In embodiments where post-irradiation heat treatment is used, the post-irradiation heat treatment can be performed at temperatures of approximately 45°C to approximately 250°C, in further embodiments approximately 50°C to approximately 190°C, and in further embodiments approximately 60°C to approximately 175°C. Post-exposure heating can generally be performed for at least approximately 0.1 minutes, in further embodiments approximately 0.5 minutes to approximately 30 minutes, and in further embodiments approximately 0.75 minutes to approximately 10 minutes. Those skilled in the art will recognize that further ranges of post-irradiation heating temperatures and times within the above-expressed ranges can be considered and that they fall within the scope of this disclosure. This high contrast in material properties further facilitates the formation of high-resolution lines with smooth edges in the developed pattern, as described in the following sections.
[0032] In the case of negative image formation, the developer may be an organic solvent, such as the solvent used to form the precursor solution. Generally, the choice of developer may be influenced by the solubility parameters for both irradiated and non-irradiated coating materials, as well as the developer's volatility, flammability, toxicity, viscosity, and potential chemical interactions with other process materials. Suitable developers include, for example, ethyl lactate, ethers (e.g., tetrahydrofuran (THF), dioxane, anisole), and ketones (e.g., 2-pentanone, 3-pentanone, hexanone, 2-heptanone, octanone). Examples demonstrate that THF and THF-anisole mixtures are preferred developers. Development can be carried out over a period of about 5 seconds to about 30 minutes, in further embodiments about 8 seconds to about 15 minutes, and in further embodiments about 10 seconds to about 10 minutes. Those skilled in the art will recognize that further ranges within the explicitly stated range above will be considered and that they fall within the scope of this disclosure.
[0033] In addition to the main developer composition, the developer may include additives to facilitate the development process. Suitable additives 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 20% by weight or less, in a further embodiment about 10% by weight or less, and in a further embodiment about 5% by weight or less. Those skilled in the art will recognize that further ranges of additive concentrations within the explicitly stated range above will be considered and that they will fall within the scope of this disclosure.
[0034] When using a weaker developer with a slower development rate, a higher temperature development process can be used to increase the process speed. When using a stronger developer, the development rate can be reduced and / or the temperature of the development process can be lowered to control the reaction rate. In general, the development temperature can be adjusted between appropriate values that are compatible with the volatility of the solvent. Furthermore, developers with 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 by any suitable method. For example, the developer can be sprayed onto the patterned coating material. Spin coating can also be used. In automated processing, a paddle method can be used in a stationary manner, involving pouring the developer onto the coating material. If necessary, spin rinsing and / or drying can be used to complete the development process. Suitable rinsing solutions include, for example, ultrapure water, aqueous tetraalkylammonium hydroxide solution, methyl alcohol, ethyl alcohol, propyl alcohol, and combinations thereof. After image development, the coating material is arranged on the substrate as a pattern.
[0036] After the development step is complete, the coating material may be heat-treated for further condensation of the material and further dehydration, densification, or removal of residual developer from the coating. This heat treatment may be particularly desirable in embodiments in which the coating material is incorporated into a final device, but may also be desirable in some embodiments in which the coating material is used as a resist and is eventually removed, if stabilization of the coating material is desired to facilitate further pattern formation. In particular, the baking of the patterned coating material can be carried out under conditions in which the patterned coating material exhibits a desired level of etching selectivity. In some embodiments, the patterned coating material can be heated to a temperature of about 80°C to about 600°C, in further embodiments about 175°C to about 500°C, and in further embodiments about 200°C to about 400°C. The heating can be carried out for at least about 1 minute, in another embodiment about 2 minutes to about 1 hour, and in further embodiments about 2.5 minutes to about 25 minutes. The heating can be carried out in air, in a vacuum, or in an inert gas environment such as Ar or N2. Those skilled in the art will recognize that further ranges of temperatures and times for heat treatment within the explicitly stated range above will be considered and will fall within the scope of this disclosure. Similarly, non-thermal treatments such as blanket UV exposure or exposure to oxidizing plasmas like O2 can also be used for the same purpose.
[0037] Wafer throughput is a substantial limiting factor for implementing EUV lithography in high-volume semiconductor manufacturing, and this is directly related to the dose required to pattern a given feature. Although chemical strategies exist to reduce the imaging dose, for EUV photoresists with feature sizes and pitches <50 nm, a negative correlation is generally observed between the imaging dose required to print the target feature and feature size uniformity (LWR, etc.), thereby limiting the operability of the final device and wafer yield. Patterning capability can be expressed as a dose-versus-gel value. The required imaging dose can be evaluated by forming a number of exposed pads, with exposure times stepped between pads to vary the exposure dose. The film can then be developed, and the thickness of the remaining resist on all pads can be evaluated, for example, using spectroscopic polarization analysis. 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-to-log dose curve is defined as the photoresist contrast (γ), and the dose value at which the tangent line drawn through this point is 1 is defined as the photoresist dose-to-gel (Dg). D0 corresponds to the starting dose for the initial increase in film thickness of the negative-type resist. Common parameters used for characterizing such photoresists can be estimated according to Mack, C. (Fundamental Principles of Optical Lithography, John Wiley & Sons, Chichester, UK; pp. 271-272, 2007, incorporated herein by reference). [Examples]
[0038] Example 1. Preparation of the precursor (C4H9Sn)4S6 This example demonstrates 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) fitted with a magnetic stirrer. Next, THF (150 mL, Aldrich) was added to the 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. The mixed solution formed a slurry, which was stirred at room temperature for 16 hours and then filtered through a Celite® short plug. 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. When the solvent and other volatile components were removed under reduced pressure, an amorphous solid was formed. This was pulverized with pentane, collected by filtration, and dried under reduced pressure to obtain (C4H9)4Sn4S6 (21.02 g, 69.5%) as a white amorphous solid.
[0040] Figure 2 shows the (C4H9Sn)4S6 in benzene-d6. 119 Sn{ 1 The ¹H NMR spectrum is shown. This spectrum shows one peak at -144.3 ppm due to the four tin atoms in a homogeneous binding environment. The benzene-d6 solvent had resonance at -149 MHz.
[0041] Figure 3 shows (C4H9Sn)4S6 in toluene-d8. 1The 1H NMR spectrum is shown. This spectrum shows resonance at -1.63 ppm (J=7.6 Hz) and a seven-blind line at -1.29 ppm (J=7.2 Hz). The integration ratio is 1:1, and each resonance pattern corresponds to the eight -CH2- hydrogen atoms of the butyl ligand. The spectrum shows a triple line at -1.46 ppm (J=7.8 Hz), which corresponds to the -CH2- proton closest to the tin atom, and a triple line at -0.80 ppm (J=7.3 Hz), which corresponds to the -CH3 proton. The integration ratio is 1:1.5, corresponding to a total of eight α-CH2- protons and a total of twelve -CH3 protons. The toluene-d8 solvent had a resonance at -500 MHz.
[0042] Figure 4 shows the (C4H9Sn)4S6 in benzene-d6. 13 The 13C NMR spectra are shown. These spectra show singlelines at -29.80 ppm, -27.43 ppm, and -26.13 ppm, corresponding to the -CH2- carbon in the butyl ligand, respectively. This spectrum also shows a singleline at -13.64 ppm, corresponding to the -CH3 carbon. The benzene-d6 solvent exhibited resonance 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 (C4H7Sn)4S6 This example demonstrates the synthesis of an n-butenyltin cluster composition.
[0045] n-butenyl tin trichloride was prepared by the reaction of 1 part (C4H7)4Sn with 3 parts SnCl4. These procedures were adapted from U.S. Patent No. 2,873,288 and the Journal of Organometallic Chemistry 691(8), 1703-1712 (2006) by Schumann, Herbert; Aksu, Yilmaz; and Wassermann, Birgit C.
[0046] (C 4 H 7 ) 4 Sn synthesis A reflux condenser and nitrogen inlet were fitted into a three-necked flask containing a large magnetic stirring bar and freshly cut magnesium shavings (42.8 g, 1.7 mol), to which THF (500 ml) was added. The solution was heated under reflux and stirred for 15 minutes. The heat source was removed, and a small amount of 3-butenyl bromide (approximately 5 mL) was added, causing the mixture to reflux. Further addition of 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 under reflux for 1 hour. The solution was cooled and then stirred at room temperature for 12 hours. Alternatively, 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 may be generated when SnCl4 is added to THF, likely due to the formation of HCl(g) by hydrolysis of SnCl4). The previously prepared 3-butenyl Grignard solution was added dropwise to the cooled SnCl4 solution. 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 silica gel short plug (200 g) and eluted with pentane. After removing volatile components under reduced pressure, the desired product (C4H7)4Sn (49 g, 51%) was obtained as a colorless liquid and confirmed by NMR as follows. 119 Sn NMR (186 MHz, chloroform-d) δ -5.64 (s, 1Sn). 1 ¹H NMR (500MHz, chloroform-d) δ 5.87 (ddt, J=16.6, 10.1, 6.3Hz, 4H, Sn-butenyl=CH), 5.01 (dq, J=17.1, 1.8Hz, 4H, Sn-butenyl=CH), 4.93 (dq, J=10.1, 1.5Hz, 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 the reaction (C4H7)4Sn (10g, 29.5 mmol) was added to a Schlenk flask and dissolved by adding toluene (25 ml) dropwise. SnCl4 (25.13g, 96.5 mmol) was added dropwise. The resulting mixture was stirred at room temperature for 2 hours, and then Cl2Pt(PPh3)2 (0.01g, 0.013 mmol) was added. Next, the mixture was... 119 The mixture was heated at 110°C for approximately 12 hours until complete conversion to the desired product was demonstrated by Sn NMR spectroscopy. The mixture was cooled to room temperature, filtered through a silica short plug, and washed three times with 20 mL of toluene. The filtrate was collected, and volatile components were removed under reduced pressure. Distillation of the product yielded a colorless oil with a boiling point of 40–75°C and a vapor pressure of 1–0.3 torr, which corresponds to the desired product (C4H7)SnCl3 (24.71 g, 88.2 mmol, yield 68.5%), and was confirmed by NMR as follows. 119 Sn NMR (149 MHz, chloroform-d δ 2.71 (s, 1Sn)). 1 ¹H NMR (400MHz, chloroform-d) δ 5.92 (ddt, J=16.7, 10.1, 6.4Hz, 1H, Sn-butenyl=CH2), 5.27 (q, J=1.4Hz, 1H, Sn-butenyl=CH), 5.25-5.20 (m, 1H, Sn-butenyl-CH), 2.67 (qt, J=6.8, 1.4Hz, 2H, Sn-butenyl-CH2), 2.45 (t, J=7.2Hz, 2H, Sn-butenyl-CH2).
[0048] (C 4 H 7 Sn) 4 S 6 synthesisSodium sulfide (17.9 g, 230 mmol, Alfa Aesar, 95%) was added to a round-bottom flask (500 mL) fitted with a magnetic stirrer. Next, THF (150 mL) was added to this flask, and the resulting solution was cooled to -78°C. The solution of (C4H7)SnCl3 (37.8 g, 135.0 mmol) in THF (60 mL) was added dropwise to the cooled sodium sulfide solution. The resulting slurry was stirred at room temperature for 16 hours and filtered through a Celite® short plug. 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 further dichloromethane, and the resulting dichloromethane solution was mixed with the first filtrate. When the solvent and volatile components were removed under reduced pressure, an amorphous solid was obtained. This was pulverized with pentane, collected by filtration, and dried under reduced pressure to obtain (C4H7Sn)4S6 (18.0 g, 60.1%) as a white solid.
[0049] Figure 5 shows (C4H7Sn)4S6 in chloroform-d. 119 The Sn NMR spectrum is shown. This spectrum shows one peak at -141.64 ppm corresponding to four tin atoms in a homogeneous binding environment. The chloroform-d solvent had a resonance at -149 MHz.
[0050] Figure 6 shows (C4H7Sn)4S6 in chloroform-d. 1The 1H NMR spectrum is shown. This spectrum shows a ddt pattern at -5.89 ppm (J=16.6, 10.1, 6.3 Hz) corresponding to one of the =CH2 hydrogens of each of the four butenyl ligands. This spectrum also shows a multiline at -5.12 to -5.04 ppm corresponding to another =CH2 hydrogen of each of the four butenyl ligands. This spectrum shows a quadruplet at -5.15 ppm (J=1.6 Hz) corresponding to four =CH hydrogens. This spectrum shows multiline and triplelines at -2.79 to -2.32 ppm (J=7.8 Hz), each pattern corresponding to eight -CH2- hydrogens, with a 1:1 integral. The chloroform-d solvent had resonance at -400 MHz.
[0051] Figure 7 shows the (C4H7Sn)4S6 in benzene-d6. 13 The 13C NMR spectrum is shown. This spectrum shows a single line at -138.40 ppm corresponding to the =CH carbon of the butenyl ligand. The single line at -116.05 ppm corresponds to the =CH2 carbon. The single lines at -29.02 ppm and -28.70 ppm correspond to the bonding environment 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 for (C4H9Sn)4S6 and (C4H7Sn)4S6 This example demonstrates the preparation of precursor solutions containing 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 from 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 ranging from 64 to 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 to 150 mM.
[0055] A photoresist precursor solution was prepared by adding 0.17 g of (C4H7Sn)4S6 from Example 2 to 20 mL of toluene. This mixture was gently heated to form a clear solution. The solution remained clear throughout the entire film deposition period. Diagnosis 1 H and 119 Sn NMR resonance indicates that this solution contains the tetramer (n-butenylSn)4S6. Further toluene solutions with tin concentrations ranging from 64 to 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 to 150 mM.
[0056] Example 4. Wafer coated with a film This example demonstrates the fabrication of a film-coated wafer and shows that thin, smooth films can be deposited using both n-butyltin and n-butenyltin cluster compositions.
[0057] A silicon wafer (10.2 cm in diameter) with a native oxide surface was used as a substrate for thin film deposition. Unless otherwise specified, films were deposited on untreated wafers by spin-coating them with a toluene-based precursor solution prepared as described in Example 3 at 1500 rpm for 30 seconds. In some cases, wafers were pre-treated by wetting with a casting solvent if useful for obtaining a good coating. In particular, a film sample (F1) with a thickness of 176 nm was prepared by spin-coating a precursor solution of (C4H9Sn)4S6(R1) in toluene with a tin concentration of 75 mM onto a wafer at 1500 rpm for 30 seconds. A film sample (F2) with a thickness of 188 nm was prepared by spin-coating a second precursor solution of (C4H7Sn)4S6(R2) in toluene with a tin concentration of 75 mM onto a wafer at 1500 rpm for 30 seconds. Figure 8 shows curve a of the FTIR spectrum of powder R1 and curve b of the FTIR spectrum of film sample F1. The results are from 3000 to 2850 cm⁻¹. -1 This indicates that the characteristic alkane CH stretch absorption and angular bending absorption at 1470-1450 cm⁻¹ are maintained. However, the membrane is maintained at 1600-500 cm⁻¹. -1 The different absorptions within this range suggest a spatial change in the structure of the Sn-S cage. Figure 9 shows curve a of the FTIR spectrum of powder R2 and curve b of the FTIR spectrum of film sample F2. These results are observed in the range 3100–2850 cm⁻¹. -1 This demonstrates that the characteristic CH stretching absorption of alkanes and alkenes is maintained.
[0058] A 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, a wafer coated with a 21.1 nm thick film of (C4H7Sn)4S6 showed a surface roughness of 0.4 nm. These results indicate that tin cluster compositions can be deposited as relatively smooth films.
[0059] A set of film samples was prepared from precursor solutions of toluene and (C4H9Sn)4S6 cluster compositions at various concentrations. Figure 10 shows the linear dependence of film thickness on the concentration of R1. A second set of film samples was prepared from precursor solutions of toluene and (C4H7Sn)4S6 cluster compositions at various concentrations. Figure 11 shows the linear dependence of film thickness on the concentration of R2. These results demonstrate that tin cluster compositions can be deposited with well-controlled thicknesses on the nanometer scale.
[0060] Example 5. Negative image formation using UV exposure This example demonstrates that UV radiation can induce negative dissolution contrast in films made from n-butyltin and n-butenyltin cluster compositions.
[0061] The film samples F1 and F2, prepared as described in Example 4, were placed in aluminum foil-lined boxes in a glove box filled with argon. The sections of film samples F1 and F2 were exposed to laboratory UV light, uniformly supplying radiation at a wavelength of approximately 354 nm to all samples for several minutes to obtain an appropriate dose, thereby obtaining film samples F1 and F2, each with exposed and unexposed film regions. 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 thickness of the exposed and unexposed sections of each film sample was measured using a JAWoollam M-2000 spectrophotometer. The normalized film thickness was calculated by dividing the thickness of the developed section by the average film thickness 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 (C4H9Sn)4S6 film completely dissolves after 30 seconds in each developer composition. 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 dissolution rate occurs after UV exposure, i.e., that UV exposure induces a chemical change and forms a latent image.
[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 0–40% anisole in THF. At 60–100% volume anisole, the dissolution of the unexposed R2 composition decreases with increasing 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 retains 97–99% of its original thickness in all tested developer compositions.
[0064] All of this data indicates that UV exposure of (C4H9Sn)4S6 and (C4H7Sn)4S6 films induces chemical changes that alter their dissolution rate. Exposure and subsequent dissolution in a mixed solution of anisole and THF reveal that these films are negative-type photoresists.
[0065] Example 6. Solubility contrast by EUV exposure This example shows the solubility contrast of the film from Example 3 after exposure to EUV radiation.
[0066] A film was deposited on a 10.2 cm diameter silicon wafer having a native oxide surface, as described in Example 4. Precursor solutions of (C4H9Sn)4S6 and (C4H7Sn)4S6 were prepared at concentrations appropriate for the deposition of R1 and R2 films of each film, with a thickness of approximately 20 nm. In the contrast curves shown in Figures 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, each approximately 500 μm in diameter, was projected onto the wafer using increasing UV exposure doses. After exposure, the film was developed with a 20% (v / v) mixture of 2-heptanone, THF, and anisole in THF, or a 40% (v / v) mixture of anisole in THF. The film was developed with or without a post-exposure bake at 100°C for 2 minutes. The thickness of each exposed pad was evaluated using a JAWoollam M-2000 spectrophotometer. The normalized thickness of each pad under various process conditions is plotted as a function of EUV dose in Figures 16 and 17 (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 is 7 mJ cm -2 The maximum value exceeding (dose versus gel, D g It rises up to ).
[0068] Table 1 shows the process conditions, developer composition, and derived results for each composition (C4H9Sn)4S6(R1) and (C4H7Sn)4S6(R2) (D o The curves a-k (Dg and contrast) are summarized. The curves a-k are shown in Figures 16 and 17.
[0069] [Table 1]
[0070] The results indicate that EUV exposure of (C4H9Sn)4S6 and (C4H7Sn)4S6 films induces chemical changes that alter the dissolution rate. Exposure and subsequent processing demonstrate that good solubility contrast can be achieved for compositions R1 and R2. Under the tested process conditions, maximum contrast was achieved by developing in THF after the bake step. Without the bake step, composition R1 yielded better contrast with 20% (v / v) anisole in THF than with THF alone. For composition R2 without the bake step, better contrast was obtained with the THF developer.
[0071] The embodiments described above are intended to be descriptive and not limiting. Further embodiments are within the scope of the claims. Furthermore, although 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 references to the above-mentioned documents are limited so as not to incorporate subject matter contrary to the express disclosure. To the extent that a particular structure, composition and / or process is described herein together with a part, element, component or other subdivision, unless otherwise specifically stated, this disclosure should be understood to include embodiments that consist of a particular part, element or other subdivision or combination thereof, and embodiments that include a particular embodiment, an embodiment that includes the particular part, element or component or other subdivision or combination thereof, and which may include further features that do not alter the fundamental nature of the subject matter as suggested in the discussion.
Claims
1. Substrate and formula (RSn) ４ X ６ A structure having a radiosensitive pattern-forming layer, which includes a radiosensitive layer containing an organotin cluster represented by (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), wherein the radiosensitive layer has an average thickness of about 2 nm to about 1 micron.
2. The structure according to claim 1, wherein R is an alkyl group, an alkenyl group, an aryl group, or a combination thereof.
3. The structure according to claim 1, wherein the organotin cluster comprises n-butyltin sulfide, n-butenyltin sulfide, or a combination thereof.
4. The radiation-sensitive layer has an average thickness of 2 nm to 200 nm, according to any one of claims 1 to 3.
5. The structure according to any one of claims 1 to 4, wherein the thickness of the layer at any location across the structure varies by 25% or less from the average thickness of the layer.
6. The structure according to any one of claims 1 to 5, wherein the radiation-sensitive pattern-forming layer comprises a material having a virtual image corresponding to a selected pattern of radiation, and the virtual image has regions having different solubility in organic solvents.
7. The structure according to any one of claims 1 to 6, wherein the radiation-sensitive layer includes a patterned layer containing a radiation-irradiated material having low solubility in an organic solvent.
8. The irradiated coating material comprises a crosslinked organotin cluster, according to any one of claims 1 to 7.
9. The substrate has the structure according to any one of claims 1 to 8, comprising a silicon wafer.
10. A pattern-forming precursor solution, Organic solvents and Formula (RSn) ４ X ６ An organotin cluster composition represented by (where R is an organic ligand bonded to Sn by a metal-carbon bond, and X is S or Se) and A pattern-forming precursor solution containing [a certain substance] and having a concentration of approximately 0.0005 M to approximately 1 M based on tin.
11. The pattern-forming precursor solution according to claim 10, having a concentration of approximately 0.0025 M to approximately 0.4 M based on tin.
12. The pattern-forming precursor solution according to claim 10 or 11, wherein the organotin cluster composition comprises n-butyltin sulfide, n-butenyltin sulfide, or a combination thereof.
13. The pattern-forming precursor solution according to any one of claims 10 to 12, wherein the organic solvent comprises benzene, toluene, 1,1,2-trichloroethane, chloroform, tetrahydrofuran (THF), anisole, derivatives thereof, or combinations thereof.
14. A method for forming a radiation-sensitive layer suitable for pattern formation on a substrate surface, (RSn) ４ X ６ The method involves depositing clusters onto a substrate, where X is S or Se, and R is a hydrocarbyl group (or organic ligand) bonded to Sn by a metal-carbon bond. Including the above, the deposition is 1) (RSn) ４ S ６ Bringing a solution containing clusters and an organic solvent into contact with the substrate surface, and The solvent is removed to form a layer of radiation-sensitive coating material. 2) the (RSn) ４ X ６ volatilizing the cluster, and Collecting the volatile clusters on the substrate surface, or 3) (RSn) ４ Y ６ (Here, Y is a halogen atom) vapor and gas H ２ Using X, (RSn) ４ X ６ Perform reactive deposition Methods that include...
15. The method according to claim 14, wherein the organic solvent includes benzene, toluene, 1,1,2-trichloroethane, chloroform, tetrahydrofuran (THF), anisole, derivatives thereof, or combinations thereof.
16. The method according to claim 14, wherein the deposition includes vapor deposition or spin coating.
17. The method according to claim 14, wherein the deposition includes the arrangement of a solution, the solution having a concentration of tin atoms of about 0.0005 M to about 1 M.
18. A method for patterning a coating, comprising exposing a radiosensitive layer to a radiation pattern to form a radiation-irradiated layer, thereby developing the pattern from a virtual image formed by the radiation-irradiated layer, wherein the development of the pattern comprises contacting the radiation-irradiated layer with an organic solvent to substantially remove the non-radiation portions of the radiation-irradiated layer, wherein the radiosensitive layer is formed using organotin clusters, and the radiation-irradiation of the radiosensitive layer results in a material that is substantially less soluble in organic solvents.
19. The method according to claim 18, wherein the radiation pattern includes a pattern of UV or EUV radiation.
20. The aforementioned EUV radiation is approximately 1 mJ / cm². ２ ~Approx. 175mJ / cm ２ The method according to claim 19, having a dose of the above.
21. The method according to any one of claims 18 to 20, wherein the organic solvent includes ethyl lactate, ethers such as tetrahydrofuran (THF), dioxane, or anisole, ketones such as 2-pentanone, 3-pentanone, hexanone, 2-heptanone, or octanone, or a combination thereof.
22. The method according to any one of claims 18 to 21, wherein contact with the organic solvent is performed for a period of about 5 seconds to about 30 minutes.