Methods for manufacturing photoresist patterns through thick film deposition, thick film deposition solutions, and methods for manufacturing processing substrates.

Abstract

[Problem] To provide a method for manufacturing a thickened photoresist pattern. [Solution] A method for manufacturing a thickened photoresist pattern comprises the following steps: (1) applying a photoresist composition onto a substrate to form a photoresist layer; (2a) exposing the photoresist layer; (2b) applying a thickening solution comprising a polymer (A) and a solvent (B) onto the photoresist layer to form a thickened layer; and (3) developing the photoresist layer and the thickened layer.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a photoresist pattern that has been thickened, the thickening solution used therein, and a method for manufacturing a substrate. Prior Technology

[0002] In recent years, the demand for high integration of LSIs has increased, requiring miniaturization of photoresist patterns. To meet this demand, lithography processes using short-wavelength KrF excimer lasers (248nm), ArF excimer lasers (193nm), extreme ultraviolet (EUV: 13nm), X-rays, electron beams, etc., are being put into practical use.

[0003] To obtain finer patterns, one method involves covering a photoresist pattern formed within a range that can be stably obtained using existing methods with a polymer-containing composition, thereby coarsening the photoresist pattern and minimizing the aperture or separation width (e.g., Patent Document 1). This method primarily aims to coarsen the width of the photoresist pattern by applying a polymer-containing composition after developing the photoresist pattern. Furthermore, in the development of photoresist patterns requiring greater thickness and higher aspect ratio, the use of compositions of vinyl resins and amine compounds is also underway (Patent Document 2). [Previous Technical Documents] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2014-170190 [Patent Document 2] Japanese Patent Application Publication No. 2017-165846 Summary of the Invention

[0005] [The problem that the invention aims to solve]

[0006] Regarding the method for manufacturing photoresist patterns, the inventors believe that there are still more than one issues that require improvement. Examples of these issues include: thickening the fine photoresist pattern; obtaining a fine photoresist pattern that can be effectively used as an etching mask; achieving sufficient resolution even when using an exposure machine with increased numerical aperture; obtaining a fine pattern with good shape; obtaining a photoresist pattern with a high aspect ratio; widening the process window; and improving manufacturing yield.

[0007] The inventors conducted their review based on the following considerations. DOF (Depth of Focus) refers to the depth of focus that, when the focus is shifted vertically during exposure at the same exposure level, allows a photoresist pattern to be formed within a predetermined range with a deviation relative to the target size. The DOF series is represented by the following formula. k2×λ / NA 2 (In the formula, k2 represents a constant, λ represents the exposure wavelength, and NA represents the numerical aperture) A larger DOF results in a wider and better process window. However, in high-precision lithography technologies such as ICs, there is a future trend towards increasing the NA (nano) of exposure equipment, which predicts that the DOF will become increasingly narrow.

[0008] EUV exposure, a highly anticipated high-precision technology, is gradually achieving the formation of fine patterns in thin films. The inventors believe that, in order to improve the durability of photoresist patterns used as masks in subsequent steps, it is suitable to thicken the photoresist pattern. If the photoresist pattern is thin, for example, when used as an etching mask, it may not be able to fully utilize its durability as a mask, and the masked object may be chipped away at the final stage of the etching step.

[0009] If the photoresist film is thick, the process window tends to narrow. For example, if the focus changes due to slight variations in substrate thickness, the shape of the resulting photoresist pattern will change, becoming significantly different from a rectangle, and potentially leading to pattern collapse. Furthermore, as another example, variations in exposure (dose) will cause linewidth variations, potentially leading to pattern bridging and pattern collapse. In high-resolution, high-precision technologies, thinner photoresist films are more readily used.

[0010] The present invention is based on the above-described technical background and provides a method for manufacturing a thick-film photoresist pattern and the thick-film solution used therein. [Methods used to solve problems]

[0011] The method for manufacturing a thick-film photoresist pattern according to the present invention comprises the following steps. (1) A photoresist composition is applied over a substrate to form a photoresist layer; (2a) Expose the photoresist layer; (2b) A thick-film solution comprising polymer (A) and solvent (B) is applied to the photoresist layer to form a thick-film layer; and (3) Develop the photoresist layer and the thick film layer.

[0012] The thick film solution according to the present invention comprises a polymer (A) and a solvent (B), and is used to thicken a photoresist layer applied before photoresist development.

[0013] The method for manufacturing a substrate according to the present invention comprises the following steps. Forming the aforementioned thick-film photoresist pattern; and (4) The photoresist pattern that has been thickened is used as a mask for processing. [The effects of the invention]

[0014] According to the present invention, one or more of the following effects can be expected. Thickening of fine photoresist patterns results in fine photoresist patterns that can be effectively used as etching masks; sufficient resolution can be obtained even when using an exposure machine with increased numerical aperture; fine patterns with good shape are obtained; photoresist patterns with high aspect ratio are obtained; the process window is widened; and manufacturing yield is improved. Simple Explanation of the Diagram

[0015] Figure 1 is a conceptual diagram showing one aspect of a method for manufacturing a thick-film photoresist pattern. Implementation

[0016] [The form in which the invention is carried out]

[0017] [definition] Unless otherwise specified and mentioned, the definitions and examples set forth in this paragraph shall prevail in this specification. The singular form contains the plural form, and "a" or "its" means "at least one". The elements of a concept may be represented by a plural number of elements, and when their quantities are recorded (e.g., mass %, moles %), their quantity means the sum of such plural elements. "and / or" includes all combinations of elements, as well as those used as individual elements. When using "~" or "-" to represent a numerical range, this system includes both endpoints, and the units are common. For example, 5~25 mol% means more than 5 mol% and less than 25 mol%. The designations "C x -y", "C x~C y", and "C x" refer to the number of carbons in a molecule or substituent. For example, C 1-6 alkyl means an alkyl chain with one to six carbons (methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.). When a polymer has a plurality of repeating units, these repeating units are copolymerized. These copolymerizations can be any of alternating copolymerization, random copolymerization, block copolymerization, graft copolymerization, or a mixture thereof. When polymers or resins are represented by structural formulas, n, m, etc., as stated in parentheses indicate the number of repeating units. Temperature is measured in Celsius. For example, 20 degrees means 20 degrees Celsius. Additives refer to the compound itself that performs its function (e.g., if it is a base-generating agent, it is the compound itself that generates base). The compound may also be dissolved or dispersed in a solvent and added to the composition. As a form of the invention, such a solvent is preferably included in the relevant composition of the invention in the form of solvent (B) or other components.

[0018] The following describes in detail the embodiments of the present invention.

[0019] <Method for manufacturing photoresist patterns using thick film> The method for manufacturing a thick-film photoresist pattern according to the present invention comprises the following steps. (1) A photoresist composition is applied over a substrate to form a photoresist layer; (2a) Expose the aforementioned photoresist layer; (2b) A thick-film solution comprising polymer (A) and solvent (B) is applied to the aforementioned photoresist layer to form a thick-film layer; and (3) Develop the aforementioned photoresist layer and the aforementioned thick film layer. The following steps are explained using diagrams. For clarity, steps (1) and (2) are performed before step (3). The numbers in the parentheses indicating the steps indicate the order. However, the order of (2a) and (2b) is arbitrary. The same applies below.

[0020] Step (1) In step (1), a photoresist composition system is applied over the substrate to form a photoresist layer. Examples of substrates include silicon / silicon dioxide coated substrates, silicon nitride substrates, silicon wafer substrates, glass substrates, and ITO substrates. The photoresist composition is not particularly limited, but from the viewpoint of forming high-resolution micro-photoresist patterns, a chemically amplified photoresist composition is preferred. For example, a chemically amplified PHS-acrylate hybrid EUV photoresist composition can be cited. The photoresist composition containing a photoacid generator is also preferred. A suitable photoresist composition of the present invention is a positively chemically amplified photoresist composition. Typical high-resolution positive photoresist compositions consist of an alkali-soluble resin with protected side chains and a photoacid generator. When a photoresist layer formed from such a composition is irradiated with ultraviolet light, an electron beam, or extreme ultraviolet light, the photoacid generator releases acid in the irradiated portion (exposed area), which dissociates the protecting groups bonded to the alkali-soluble resin (hereinafter referred to as deprotection). The deprotected alkali-soluble resin is soluble in an alkaline developer and is therefore removed by development. In the case of this application where a thick film layer is formed on top of the photoresist layer, if the underlying photoresist layer is soluble, the mixed layer and the photoresist layer in that region are removed together. (To be discussed later.) The photoresist composition of the present invention can also use a negative photoresist composition. Known negative photoresist compositions and processes can be used. For example, by using a crosslinking agent to make the polymer insoluble, or by using an organic solvent in the developer, the photoresist layer and the mixed layer in the unexposed portion can be removed together.

[0021] A photoresist composition is applied above a substrate using a suitable method. Here, in this invention, "above the substrate" includes both the case where it is applied directly above the substrate and the case where it is applied with other layers in between. For example, a photoresist underlayer film (e.g., SOC (Spin On Carbon) and / or an adhering reinforcement film) can be formed directly above the substrate, and the photoresist composition can be applied directly above it. Suitablely, the photoresist composition is applied directly above the substrate. Furthermore, in another suitable embodiment, an SOC is formed directly above the substrate, an adhering reinforcement film is formed directly above the SOC, and the photoresist composition is applied directly above it. There are no particular limitations on the application method; for example, spin coating can be used. The photoresist layer on the substrate to which the photoresist composition is applied is preferably formed by heating. This heating is also called pre-baking and is performed, for example, by a heating plate. The heating temperature is preferably 100~250°C; more preferably 100~200°C; and even more preferably 100~160°C. The temperature here refers to the temperature of the heated surface of the heating plate. The heating time is preferably 30~300 seconds; more preferably 30~120 seconds; and even more preferably 45~90 seconds. Heating is preferably performed in an atmospheric or nitrogen atmosphere; more preferably in an atmospheric atmosphere. Figure 1(i) is a schematic diagram of a photoresist layer 2 formed on a substrate 1. The thickness of the photoresist layer is selected according to the purpose, preferably 10~100 nm; more preferably 10~40 nm; and even more preferably 10~30 nm.

[0022] Step (2a) In step (2a), the photoresist layer is exposed through the mask as desired. There is no particular limitation on the wavelength of the radiation (light) used for exposure, but exposure with wavelengths of 13.5 to 248 nm is preferred. Specifically, KrF excimer lasers (wavelength 248 nm), ArF excimer lasers (wavelength 193 nm), and EUV (extreme ultraviolet light, wavelength 13.5 nm) can be used. EUV light is preferred. These wavelengths are permissible within a range of ±1%. After exposure, post-exposure heating (PEB) can be performed as needed. The PEB temperature can be selected from 70 to 150°C, preferably 80 to 120°C. The PEB heating time can be selected from 0.3 to 5 minutes, preferably 0.5 to 2 minutes. Figure 1(ii) is a schematic diagram showing the exposure of photoresist layer 2, which uses a typical positive chemical amplification photoresist composition, through a mask. In the exposed section 4, acid is released from the photoacid generator, thereby deprotecting the polymer and increasing its alkali solubility. In the unexposed section 3, the alkali solubility of the polymer remains unchanged.

[0023] Step (2b) In step (2b), a thickening solution comprising polymer (A) and solvent (B) is applied to the photoresist layer to form a thickening layer. In this invention, the thickening solution is not applied between the photoresist patterns (after the photoresist layer has been developed). There are no particular limitations on the application method; for example, spin coating can be used. The substrate to which the thickening solution has been applied is preferably formed into a thick film layer by heating or spin drying (more preferably by heating). Heating is performed, for example, by a heating plate. The heating temperature is preferably 45~150°C; more preferably 90~130°C. The heating time is preferably 30~180 seconds; more preferably 45~90 seconds. Heating is preferably performed in an atmospheric or nitrogen atmosphere; more preferably in an atmospheric atmosphere. The heating in (2b) is also referred to as mixing bake. The order of (2a) and (2b) is arbitrary. Since the thick film layer can be transmitted without exposure, it is more suitable to perform step (2b) after (2a). Alternatively, step (2a) can be performed after (2b). In this case, it is more suitable to control the influence of the thick film layer before exposure. Figure 1(iii) is a schematic diagram of a state in which a thick film layer 5 is formed on the photoresist layer 2.

[0024] In step (2b), it is preferable to form an insoluble layer in the vicinity of the junction between the thickened layer and the photoresist layer. While not theoretically limited, it is generally accepted that the polymers in the junction of the thickened layer and the photoresist layer permeate (mix) to form a mixed layer. Whether the mixed layer is soluble or insoluble in the developing solution of the subsequent developing step depends on whether the underlying photoresist layer is soluble or insoluble in the developing solution. If the area of ​​the underlying photoresist layer is insoluble in the developing solution, the mixed layer becomes an insoluble layer. If the area of ​​the underlying photoresist layer is soluble in the developing solution, the mixed layer also becomes soluble. Let's take a positive photoresist layer as an example. Since the exposed portion of the aforementioned photoresist layer is soluble in the developer, the photoresist layer (matrix component, preferably a polymer) penetrating the same area of ​​the mixed layer will dissolve, and the mixed layer will also dissolve. Furthermore, the exposed portion of the photoresist layer beneath the mixed layer will also dissolve. On the other hand, the unexposed portion of the aforementioned photoresist layer is insoluble in the developer (e.g., no deprotection has been performed). Therefore, the photoresist layer penetrating the same area of ​​the mixed layer is insoluble, and the mixed layer will not dissolve. Furthermore, the unexposed portion of the photoresist layer beneath the mixed layer will not dissolve. Figure 1(iv) is a schematic diagram showing the state in which the insoluble layer 6 is formed. Although a mixed layer is also formed in the dissolved area (the exposed area in the positive aspect), it is dissolved and removed during the development step, so it is not shown in (iv) for the sake of simplicity.

[0025] In step (2b), it is also suitable to perform rinsing after the formation of the thickened layer to remove the upper part of the thickened layer (the thickened layer above the mixing layer). Rinsing can be performed using a substance with the same composition as the solvent (B) of the thickening solution; water (e.g., DIW) is suitable. The rinsing system in this invention differs from the development described later. That is, rinsing is not for dissolving soluble areas of the photoresist layer to form a photoresist pattern.

[0026] [Thick film solution] The thickening solution according to the present invention comprises a polymer (A) and a solvent (B), and is used to thicken a photoresist layer applied before photoresist development. The thickening solution according to the present invention is not applied between photoresist patterns after development. However, the term "development after development" here does not include the development during the patterning of the removed photoresist layer. For example, in the case of a design that involves multiple consecutive photoresist patterning steps, the thickening solution of the present invention can still be used to thicken the photoresist layer in subsequent steps, even after the development of the photoresist in the preceding steps.

[0027] (A) Polymer The polymer (A) used in this invention is not particularly limited as long as it has good affinity with the photoresist pattern. Examples include polyacrylic acid and vinyl resin. Preferably, polymer (A) is a polymer in which amine groups are included in the repeating unit. Here, amine groups refer to primary amine groups (-NH₂), secondary amine groups (-NHR), and tertiary amine groups (-NRR'). Here, amine groups are also provided that allow nitrogen to bond to adjacent elements through a double bond, such as -N=. These amine groups can be included in the side chain of the repeating unit or in the main chain structure of the polymer.

[0028] Polymer (A) is preferably a polymer comprising at least one of a repeating unit (A1) represented by formula (a1) and a repeating unit (A2) represented by formula (a2). More preferably, polymer (A) is a state comprising a repeating unit (A1) represented by formula (a1).

[0029] The repeating unit (A1) represented by equation (a1) is as follows. R11, R12, and R13 are each independently H, C1-4 alkyl, or carboxyl. R11 and R12 are preferably H. R13 is preferably H or methyl; more preferably H. L 11 is a single bond or a C1-4 alkyl group; preferably a single bond or a methylene group; more preferably a single bond. R14 is a single bond, H, or C1-5 alkyl; preferably a single bond, H, methyl, n-ethyl, n-propyl, or n-butyl; more preferably a single bond, H, or methyl. When R14 is a single bond, it is bonded to R13. R 15 is H, C1-5 alkyl, C1-5 acetyl, or methyl (-CHO); preferably H, methyl, ethyl, n-propyl, n-butyl, acetyl, or methyl; more preferably H, methyl, n-ethyl, or n-propyl; and even more preferably H or n-propyl. At least one of the -CH2- groups in the alkyl group of L11, the alkyl group of R14, and the alkyl or acetyl group of R15 may be independently substituted with -NH-. Preferably, one of the -CH2- groups in the alkyl or acetyl group of R15 is substituted with -NH-. The state in which no such substitution with -NH- occurs is also suitable. The single bond or alkyl group of R14 and the alkyl group of R13 can bond together to form a saturated or unsaturated heterocycle. Preferably, the single bond of R14 and the alkyl group of R13 bond together to form a saturated heterocycle. States that do not form the aforementioned heterocycles are also suitable. The alkyl group of R14 and the alkyl, acetyl, or methyl group of R15 can be bonded together to form a saturated or unsaturated heterocycle. Preferably, the alkyl group of R14 and the alkyl group of R15 are bonded to form an unsaturated heterocycle. The -CH2- in R14 and / or R15 used for the aforementioned bonding can be substituted with the aforementioned -NH-. States that do not form the aforementioned heterocycle are also suitable. m11 and m12 are each independently a number from 0 to 1; preferably 0 or 1; even more preferably 0.

[0030] The repeating unit of P1, polyvinylimidazole, described later, is illustrated by formula (a1). m11=m12=0. R11, R12, and R13 are H. L11 is a single bond. R14 is methyl. R15 is a C3 alkyl (n-propyl), with one of the -CH2- groups substituted with -NH-. Furthermore, the alkyl groups of R14 and R15 are bonded together to form an unsaturated heterocycle (imidazole). The repeating unit P2, polyallylamine, described later, is illustrated by formula (a1). m11 = m12 = 0. R11, R12, and R13 are H. L11 is methylene. R14 and R15 are H. The repeating unit of P3, the vinylpyrrolidone-vinylimidazolium copolymer described later, is illustrated by formula (a1). The polymer having (A1) has two repeating units, each represented by formula (a1). The vinylimidazolium site is the same as that of P1 described above. The vinylpyrrolidone site will be explained. m11=m12=0. R11, R12, and R13 are H. L11 is a single bond. R14 is a C2 alkyl (ethyl). R15 is a C2 acetyl (CH3-CO-, acetyl). The alkyl group of R14 and the acetyl group of R15 are bonded to form a saturated heterocycle (2-pyrrolidone). The repeating units belonging to the vinylimidazolium and vinylpyrrolidone sites are randomly copolymerized in a 4:6 ratio.

[0031] The repeating unit of the following polydiallylamine is illustrated by formula (a1). m11=m12=1. R11 and R12 are H. L11 is methylene, and R13 is methyl. R14 is a single bond, bonded to R13 to form a saturated heterocycle. R15 is H. The following repeating unit is illustrated by formula (a1). m11=m12=0. R11, R12, and R13 are H. L11 is a single bond. R14 is a C4 alkyl (n-butyl). R15 is a C2 acetyl (CH3-CO-, acetyl). The alkyl group of R14 and the acetyl group of R15 are bonded together to form a saturated heterocycle.

[0032] Examples of polymers having (A1) include: polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, and vinylpyrrolidone-vinylimidazole copolymers. Polymer (A) can be a copolymer having two or more (A1) units; for example, vinylpyrrolidone-vinylimidazole copolymers or poly(allylamine-co-diallylamine) can be examples. The repeating units contained in a polymer having (A1) are preferably one or two types; more preferably one type. When using copolymers, the repeating units contained in a polymer having (A1) are preferably two types.

[0033] The repeating unit (A2) represented by equation (a2) is as follows. Here, R 21 is independently H, a single bond, a C1-4 alkyl group, or a carboxyl group (-COOH); preferably H, a single bond, or a methyl group; more preferably H or a single bond; and even more preferably H. The single bond of R 21 is used in the repeating unit leading to another repeating unit (A2). Unused single bonds at the ends of the polymer may be bonded with H, etc. R22, R23, R24, and R25 are each independently H, C1-4 alkyl, or carboxyl; preferably H or methyl; more preferably H. m21 is a number from 0 to 3; preferably 0 or 1; even more preferably 1.

[0034] As an example of a polymer having (A2), polyethylene imine can be cited. Polyethylene imine can be linear or branched; linear is more suitable. The linear poly(ethylene imine) is illustrated by equation (a2). m21=1, R21, R22, R23, R24 and R25 are H. Branched poly(ethylene imine) is described by equation (a2). m21=1, R21 is H or a single bond. R22, R23, R24 and R25 are H. Polymer (A) can be a copolymer having two or more (A2) units. The repeating units contained in a polymer having (A2) are preferably one or two types; more preferably one type. Polymer (A) can be a copolymer having (A1) and (A2).

[0035] The polymer (A) can be suitably selected from the above-mentioned sources from the viewpoint of the type of photoresist composition applied and the ease of obtaining the polymer, and is preferably selected from the group comprising polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, polyvinyl ethylimide, vinylpyrrolidone-vinylimidazole copolymer and poly(allylamine-co-diallylamine).

[0036] Polymer (A) may be a copolymer comprising repeating units without amine groups, within the scope of this invention. Examples include copolymers comprising polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, etc., as copolymerizing units.

[0037] Considering the affinity with the polymer in the photoresist, the amino-free repeating units, based on the total repeating units constituting polymer (A), are preferably 50 mol% or less; more preferably 30 mol% or less; and even more preferably 5 mol% or less. An amino-free repeating unit content of 0 mol% (excluding) is also a suitable aspect of the present invention.

[0038] The polymer (A) preferably has a mass-average molecular weight of 5,000 to 200,000; more preferably 5,000 to 150,000; and even more preferably 6,000 to 10,000. In this invention, the mass-average molecular weight (Mw) refers to the converted mass-average molecular weight of polystyrene determined using gel permeation chromatography.

[0039] The content of polymer (A) is based on the total mass of the thick film solution, preferably 1 to 30% by mass; more preferably 1 to 20% by mass; and even more preferably 2 to 10% by mass. The thick film forming solution contains polymer (A), but may also contain polymers other than polymer (A) (preferably polymers with repeating units that do not contain amine groups). The content of polymers other than polymer (A) is based on the total mass of the thick film forming solution, preferably 0 to 20% by mass; more preferably 0 to 10% by mass; even more preferably 0 to 5% by mass; and even more preferably 0% by mass (excluding the form).

[0040] (B)solvent Solvent (B) is used to dissolve polymer (A) and other components as needed. Such solvent must not dissolve the photoresist layer. Solvent (B) is preferably composed of water. Deionized water (DIW) is suitable. For forming fine photoresist patterns, solvent (B) is preferably low in impurities. Preferably, solvent (B) has impurities of 1 ppm or less; more preferably 100 ppb or less; and even more preferably 10 ppb or less. Filtering the solution containing the solute to prepare a thick-film solution for use in fine processes is also a suitable aspect of this invention. The water content, based on the total mass of solvent (B), is preferably 80-100% by mass, more preferably 90-100% by mass, even more preferably 98-100% by mass, and still more preferably 100% by mass. As a suitable embodiment of the invention, solvent (B) substantially contains only water. However, additives in a solvent other than water (e.g., surfactants), contained in the thick-film solution according to the invention, are permissible as a suitable embodiment of the invention.

[0041] Specific examples of solvents other than water (B) include: cyclohexanone, cyclopentanone, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol-1-monomethyl ether-2-acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, γ-butyrolactone, ethyl lactate, or mixtures thereof. These exhibit better stability in solution. Two or more of these solvents can also be mixed for use.

[0042] The content of solvent (B) is based on the total mass of the thick film solution, preferably 70-99% by mass; more preferably 80-99% by mass; and even more preferably 90-98% by mass. The optimal pH of the thick film solution is 5-12; better is 7-12; and even better is 9-12.

[0043] (C) acid The thick-film solution according to the present invention can further contain acid (C). While not theoretically limited, it is considered that the pH of the thick-film solution, which tends to become alkaline due to the polymer (A), can be adjusted by containing acid (C). It is believed that this can inhibit the dissolution of the polymer present on the surface of the photoresist layer, which is intended to protect the photoresist layer. Examples of acids (C) include: sulfonic acids, carboxylic acids, sulfuric acid, nitric acid, or mixtures of at least two of these; sulfonic acids, sulfuric acid, or nitric acid are suitable; more suitable are sulfonic acids or nitric acid. Examples of sulfonic acids include, for example: p-toluenesulfonic acid, benzenesulfonic acid, p-dodecylbenzenesulfonic acid, 1,4-naphthalenedisulfonic acid, methanesulfonic acid; p-toluenesulfonic acid is suitable. Examples of carboxylic acids include, for example: acetic acid, formic acid, oxalic acid, maleic acid, fumaric acid, phthalic acid, succinic acid. The overall pH can be controlled by the amount of acid (C) added. It is preferable to avoid using strong acids (C) that would modify the photoresist film. For example, it is suitable that the photoresist film is not deprotected by the acid (C).

[0044] The acid (C) content, based on the total mass of the thick film solution, is preferably 0-20% by mass; more preferably 0-15% by mass; even more preferably 0.1-10% by mass; and still more preferably 0.1-5% by mass. A preferred form of the invention is that the thick film solution contains no acid (C) (0% by mass).

[0045] (D) Surfactants The thick film solution according to the present invention can further include a surfactant (D). By including the surfactant (D), the coatability can be improved. Examples of surfactants that can be used in the present invention include: (I) anionic surfactants, (II) cationic surfactants, or (III) nonionic surfactants. More specifically, examples include: (I) alkyl sulfonates, alkylbenzene sulfonic acids, and alkylbenzene sulfonates; (II) laurylpyridinium chloride and laurylmethylammonium chloride; and (III) polyoxyethylene acetylenic glycol ether, polyoxyethylene lauryl ether, polyoxyethylene acetylenic glycol ether, fluorinated surfactants (e.g., Fluorad (3M), Megafac (DIC), Surflon (Asahi Glass)), and organosiloxane surfactants (e.g., KF-53, KP341 (Shin-Etsu Chemical Industry)). These surfactants can be used alone or in combination of two or more.

[0046] The content of surfactant (D) is based on the total mass of the thick film solution, preferably 0-5% by mass; more preferably 0.001-2% by mass; and even more preferably 0.01-1% by mass. The absence of surfactant (D) (0% by mass) is also a form of the present invention.

[0047] (E) Additives The thick-film solution according to the present invention can further contain additive (E) in addition to the components (A) to (D) described above. Additive (E) is preferably a plasticizer, crosslinking agent, antibacterial agent, bactericide, preservative, antifungal agent, alkali, or a mixture of at least any of these. Additive (E) is suitable to contain an alkali; more preferably, it is composed of an alkali. The alkali system differs from the amine-containing polymer (A) in that it is a low-molecular-weight compound. The molecular weight of the low-molecular-weight compound is 50 to 200; preferably 70 to 150; more preferably 100 to 125. Examples of such bases include tertiary amines, diamines, and amine compounds with cage-like stereostructures. Examples of diamine compounds include: N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N',N'-tetrapropylethylenediamine, N,N,N',N'-tetraisopropylethylenediamine, N,N,N',N'-tetramethyl-1,2-propanediamine, N,N,N',N'-tetraethyl-1,2-propanediamine, and N,N,N' N'-Tetrapropyl-1,2-propanediamine, N,N,N',N'-Tetraisopropyl-1,2-propanediamine, N,N,N',N'-Tetramethyl-1,3-propanediamine, N,N,N',N'-Tetraethyl-1,3-propanediamine, N,N,N',N'-Tetrapropyl-1,3-propanediamine, N,N,N',N'-Tetraisopropyl-1,3-propanediamine, N,N, N',N'-Tetramethyl-1,2-Butanediamine, N,N,N',N'-Tetraethyl-1,2-Butanediamine, N,N,N',N'-Tetrapropyl-1,2-Butanediamine, N,N,N',N'-Tetraisopropyl-1,2-Butanediamine, N,N,N',N'-Tetramethyl-1,3-Butanediamine, N,N,N',N'-Tetraethyl-1,3-Butanediamine, N,N N',N'-Tetrapropyl-1,3-Butanediamine, N,N,N',N'-Tetraisopropyl-1,3-Butanediamine, N,N,N',N'-Tetramethyl-1,4-Butanediamine, N,N,N',N'-Tetraethyl-1,4-Butanediamine, N,N,N',N'-Tetrapropyl-1,4-Butanediamine, and N,N,N',N'-Tetraisopropyl-1,4-Butanediamine. Examples of amine compounds with a cage-like stereostructure include: 1,4-diazabicyclo[2.2.2]octane, 2-methyl-1,4-diazabicyclo[2.2.2]octane, 1,4-diazabicyclo[2.2.2]octane-2-one, 1,4-diaza-2-oxabicyclo[2.2.2]octane, 1,5-diazabicyclo[3.2.2]nonane, 1,5-diazabicyclo[3.3.2]decane, and 1,5-diazabicyclo[3.3.3]undecane. The base of additive (E) being 1,4-diazabicyclo[2.2.2]octane is a suitable embodiment of the present invention. While not theoretically limited, it is considered that the base containing additive (E) promotes the penetration of the thick-film solution into the photoresist layer, resulting in greater expansion of the underlying photoresist layer.

[0048] The content of additive (E) is based on the total mass of the thick film solution, preferably 0-10% by mass; more preferably 0.001-5% by mass; even more preferably 0.01-4% by mass; and still more preferably 0.1-3% by mass. A preferred form of the present invention is a thick film solution that does not contain additive (E) (0% by mass).

[0049] Step (3) In step (3), the photoresist layer and the thickened film layer are developed. Methods of applying the developer include, for example, immersion, dipping, and spraying. The preferred developing temperature is 5–50°C; more preferably 25–40°C. The preferred developing time is 15–120 seconds; more preferably 30–60 seconds. After application, the developer is removed. The developed photoresist pattern can also be rinsed. Rinsing can be performed with water (DIW). The developer is preferably an alkaline aqueous solution or an organic solvent; more preferably, it is an alkaline aqueous solution. Examples of alkaline aqueous solutions include: aqueous solutions containing inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium silicate; organic amines such as ammonia, ethylamine, propylamine, diethylamine, diethylaminoethanol, and triethylamine; and quaternary amines such as tetramethylammonium hydroxide (TMAH); more preferably, it is an aqueous solution of TMAH; and even more preferably, it is an aqueous solution of 2.38% by mass of TMAH. The aforementioned surfactants can also be further added to the developer.

[0050] Figure 1(v) shows the state of the photoresist pattern 7 formed by applying developer to the photoresist layer and the thickened layer, removing the developer, and forming the thickened photoresist pattern 7. If the thickness of the photoresist is defined as (height of the photoresist pattern after thickening) - (height of the photoresist pattern formed similarly without the application of a thickening solution), then the thickness is preferably 2~20 nm; more preferably 2~15 nm; even more preferably 3~10 nm; and even more preferably 3~8 nm. While not theoretically limited, it is considered that in high-precision lithography techniques such as EUV exposure, the photoresist film is generally thin; however, by using this invention to thicken it, it is possible to ensure the durability of the mask when used in subsequent steps, such as as an etching mask.

[0051] <Manufacturing Method of Processing Substrates and Devices> The method for manufacturing a substrate according to the present invention comprises the following steps. Forming the thick-film photoresist pattern described above; and (4) The photoresist pattern that has been thickened is used as a mask for processing.

[0052] Step (4) In step (4), the photoresist pattern that has been thickened is used as a mask for processing. Thickened photoresist patterns are preferably used for processing photoresist underlayers or substrates (more preferably substrates). Specifically, the photoresist pattern can be used as a mask to process various substrates that will become the substrate using dry etching, wet etching, ion implantation, metal plating, and other methods. Because the photoresist pattern is thickened, it can function as a mask even under more demanding conditions, making it suitable for dry etching-based processing. When using thickened photoresist patterns to fabricate the photoresist underlayer, the processing can be performed in stages. For example, a photoresist pattern can be used to fabricate a bonding reinforcement film and a SOC, and a SOC pattern can be used to fabricate the substrate. The bonding reinforcement film can use, for example, SiARC (Si antireflective film).

[0053] The method for manufacturing the device according to the present invention comprises the above-described method, and preferably further comprises the step of forming wiring on a processed substrate. These processes can be performed using known methods. Then, as needed, the substrate is cut into wafers, connected to a lead frame, and encapsulated with resin. In the present invention, this encapsulated device is referred to as a device. Examples of devices include: semiconductor elements, liquid crystal display elements, organic EL display elements, plasma display elements, and solar cell elements. A preferred device is a semiconductor element. [Example]

[0054] The present invention will be illustrated below using various examples. However, the nature of the present invention is not limited to these examples.

[0055] [Preparation of Thick Film Forming Solutions 1-3] The polymer (A), surfactant (D), and alkali (E) listed in Table 1 are dissolved in solvent (B). The respective blending amounts are shown in Table 1. The values ​​in Table 1 are the content (mass %) of each component based on the total mass of the thick film solution. The obtained solution was stirred at room temperature for 60 minutes. After visually confirming that the solute was completely dissolved, the solution was filtered through a 0.2 μm fluorinated resin filter to obtain thick film solutions 1-3. [Table 1] Table 1 Polymer (A) Solvent(B) Surfactants (D) Alkali (E) Thick film solution 1 P1 5.0% DIW 93.45% S1 0.05% 1,4-Diazabicyclo[2.2.2]octane 1.5% Thick film solution 2 P2 5.0% DIW 92.95% S1 0.05% 1,4-Diazabicyclo[2.2.2]octane 2.0% Thick film solution 3 P3 5.0% DIW 92.95% S1 0.05% 1,4-Diazabicyclo[2.2.2]octane 2.0% In the table, P1: Polyvinylimidazolium (Mw 30,000), P2: Polyallylamine (Mw 8,000), P3: Vinylpyrrolidone, vinylimidazole, random copolymer (m:n=4:6, Mw 25,000), S1: An acetylene diol polyoxyalkylene ether having the following structure.

[0056] [Example 1] A silicon substrate was treated with HMDS (hexamethyldisilazane) at 90°C for 30 seconds. A chemically amplified PHS-acrylate mixed photoresist composition (positive type) was then spin-coated onto the HMDS-treated substrate and heated at 110°C for 60 seconds to form a 35nm thick photoresist layer. Using an EUV exposure apparatus (NXE:3300B, ASML), the photoresist layer was exposed by varying the exposure amount through an 18nm (line:space = 1:1) mask. Afterwards, post-exposure heating (PEB) was performed at 100°C for 60 seconds. Subsequently, a thickening solution 1 was spin-coated onto the photoresist layer to form a thickened layer, which was then heated at 130°C for 60 seconds. Next, a 2.38% (w / w) TMAH aqueous solution was used as the developer, and the substrate was immersed for 30 seconds. While the developer was immersed in the substrate, water was dripped on it, and the substrate was rotated while the water dripped, replacing the developer with water. Then, the substrate was rotated at high speed to dry the photoresist pattern of Example 1 after thickening.

[0057] For comparison, a photoresist pattern was formed without the application of a thick-film solution. Specifically, except for the application of the thick-film solution and subsequent heating, the photoresist pattern was formed in the same manner as in Example 1. This is referred to as the comparative photoresist pattern.

[0058] [evaluate] The photoresist pattern of Example 1 after thickening and the comparison photoresist pattern were respectively made into substrate slices. The cross-sectional shape was observed using SEM (SU8230, Hitachi High Tech Fielding), and the height of the pattern was measured. The thickness was calculated as (height of the photoresist pattern after thickening) - (height of the comparison photoresist pattern). The results are recorded in Table 2. Examples 2 and 3 were performed in the same manner as in Example 1, except that the type of thick-film solution was changed to that listed in Table 2, and the amount of thick film was calculated. The results are recorded in Table 2. [Table 2] Table 2 Thick film thickness (nm) Example 1 Thick film solution 1 5 Example 2 Thick film solution 2 4 Example 3 Thick film solution 3 4

[0059] 1:Substrate 2: Photoresist layer 3: Unexposed Department 4: Exposure Department 5: Thick film layer 6: Insoluble layer 7: Photoresist pattern formed by thick film 8: Height of the photoresist pattern after thick film formation

Claims

1. A method for manufacturing a photoresist pattern with thick film, comprising the following steps: (1) applying a photoresist composition onto a substrate to form a photoresist layer; (2a) exposing the photoresist layer; (2b) applying a thick film solution comprising a polymer (A) and a solvent (B) onto the photoresist layer to form a thick film layer, and rinsing after forming the thick film layer to remove the upper part of the thick film layer; and (3) developing the photoresist layer and the thick film layer.

2. The method of claim 1, wherein in step (2b), an insoluble layer is formed in the vicinity of the thick film layer and the photoresist layer.

3. The method of claim 1 or 2, wherein the polymer (A) is a polymer comprising an amino group in a repeating unit.

4. The method of claim 1 or 2, wherein the polymer (A) is a polymer comprising at least one of a repeating unit (A1) represented by formula (a1) and a repeating unit (A2) represented by formula (a2).

4. Here, R11, R12, and R13 are each independently H, C1-4 alkyl, or carboxyl; L11 is a single bond or C1-4 alkyl; R14 is a single bond, H, or C1-5 alkyl; and R15 is H, C1-5 alkyl, C1-5 acetyl, or methylamide. Here, at least one of the -CH2- groups in the alkyl group of L11, the alkyl group of R14, and the alkyl or acetyl group of R15 can be independently substituted with -NH-. The single bond or alkyl group of R14 and the alkyl group of R13 can be bonded together to form a saturated or unsaturated heterocycle. The alkyl group of R14 and the alkyl group, acetyl, or methylamide group of R15 can be bonded together to form a saturated or unsaturated heterocycle. m11 and m12 are each independently numbered from 0 to 1.

4. Here, R21 is independently H, a single bond, a C1-4 alkyl group or a carboxyl group, R22, R23, R24 and R25 are independently H, a C1-4 alkyl group or a carboxyl group, and m21 is 0 to 3.

5. The method of claim 1 or 2, wherein the polymer (A) is selected from the group consisting of polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, polyvinyl ethylimide, vinylpyrrolidone-vinylimidazole copolymer, and poly(allylamine-co-diallylamine).

6. The method of claim 1 or 2, wherein the solvent (B) comprises water.

7. The method of claim 1 or 2, wherein the thick film solution further comprises an acid (C).

8. The method of claim 1 or 2, wherein the thick film solution further comprises a surfactant (D).

9. The method of claim 1 or 2, wherein the photoresist composition is a chemically amplified photoresist composition.

10. The method of claim 9, wherein the photoresist composition further comprises a photoacid generator.

11. A method for manufacturing a substrate comprising the steps of: forming a thickened photoresist pattern by any one of claims 1 to 10; and (4) processing the thickened photoresist pattern as a mask.

12. A method for manufacturing an apparatus comprising the method of claim 11.

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