Method for manufacturing a thickened resist pattern, a thickening solution, and a method for manufacturing a processed substrate.

Abstract

To provide a method for producing a thick resist pattern. A method for producing a thickened resist pattern comprises the following steps: (1) applying a resist composition over a substrate and forming a resist layer from the resist composition; (2a) exposing the resist layer; (2b) applying a thickening solution comprising a polymer (A) and a solvent (B) to the resist layer to form a thickening layer; and (3) Developing the resist layer and the thickened layer.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a thickened resist pattern, a thickening solution used therefor, and a method for producing a processed substrate. [Background Art]

[0002] In recent years, the demand for higher integration of LSIs has been increasing, and finer resist patterns are required. To meet such demands, lithography processes using short-wavelength light sources such as KrF excimer laser (248 nm), ArF excimer laser (193 nm), extreme ultraviolet (EUV; 13 nm), X-rays, and electron beams are being put into practical use.

[0003] To obtain finer patterns, there is a method in which a resist pattern formed within a range that can be stably obtained by conventional methods is covered with a polymer-containing composition to thicken the resist pattern, thereby reducing the hole diameter or the separation width (for example, Patent Document 1). This method is mainly aimed at increasing the width of the resist pattern, and involves developing the resist pattern once and then applying a polymer-containing composition thereto. Amid the demand for thicker resist patterns with higher aspect ratios, compositions using vinyl resin and an amine compound have also been developed (Patent Document 2) [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-170190 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2017-165846 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] The inventors of this invention believe that there is still one or more issues that need improvement in the method of manufacturing resist patterns. These include, for example: making fine resist patterns thicker; obtaining fine resist patterns useful as etching masks; obtaining sufficient resolution even when using an exposure machine with an increased numerical aperture; obtaining fine patterns with good shape; obtaining resist patterns with a high aspect ratio; widening the process window; and improving the manufacturing yield.

[0006] The inventors considered and investigated the following: DOF (Depth of Focus) refers to the range of depth of field in which, with the same exposure dose, a resist pattern can be formed with dimensions such that the deviation from the target dimensions is within a predetermined range when the focus is shifted vertically during exposure. DOF is expressed by the following formula: k² × λ / NA 2 (In the formula, k² is a constant, λ is the exposure wavelength, and NA is the numerical aperture.) A larger DOF is preferable because it widens the process window. However, in high-precision lithography technologies such as ICs, the numerical aperture (NA) of exposure equipment is expected to increase in the future, and the DOF is likely to become increasingly narrow.

[0007] EUV lithography, a promising high-resolution technology, is achieving the formation of fine patterns in thin films. The inventors of this invention considered that it is preferable to thicken the resist pattern to provide greater durability when using the high-resolution pattern as a mask in subsequent processes. If the resist pattern is thin, for example, when used as an etching mask, it may not be able to perform its function as a mask, and the object being masked may be removed towards the end of the etching process.

[0008] A thicker resist film tends to narrow the process window. For example, even slight variations in substrate thickness can cause the focus to shift, altering the shape of the formed resist pattern, deviating from a rectangle, and potentially leading to pattern distortion. Another example is that variations in exposure dose can cause variations in line width, potentially increasing the likelihood of pattern bridging and distortion. In high-resolution technologies requiring high resolution, thinner resist films are generally preferred.

[0009] This invention is based on the technical background described above and provides a method for manufacturing a thickened resist pattern and a thickening solution used therefor. [Means for solving the problem]

[0010] The method for producing a thickened resist pattern according to the present invention comprises the following steps. (1) Applying a resist composition to a substrate to form a resist layer from the resist composition; (2a) Exposing the resist layer; (2b) Applying a thickening solution comprising polymer (A) and solvent (B) to the resist layer to form a thickened layer; and (3) Develop the resist layer and the thickened layer.

[0011] The thick-film solution according to the present invention comprises a polymer (A) and a solvent (B), and is used to thicken a resist layer that is applied before development of the resist layer.

[0012] The method for manufacturing a processed substrate according to the present invention comprises the following steps. Forming the above-mentioned thickened resist pattern; and (4) Processing using a thickened resist pattern as a mask. [Effects of the Invention]

[0013] According to the present invention, one or more of the following effects can be desired. To create thicker films from fine resist patterns; to obtain fine resist patterns useful as etching masks; to achieve sufficient resolution even when using exposure machines with increased numerical aperture; to obtain fine patterns with good shape; to obtain resist patterns with a high aspect ratio; to widen the process window; and to improve manufacturing yield. [Brief explanation of the drawing]

[0014] [Figure 1] A conceptual diagram illustrating one method for manufacturing thick-film resist patterns. [Modes for carrying out the invention]

[0015] [Definition] In this specification, unless otherwise specified, the definitions and examples set forth in this paragraph shall prevail. The singular form includes the plural form, and "one" or "that" means "at least one." An element of a certain concept can be expressed by multiple types, and when a quantity (e.g., mass %) is given, that quantity represents the sum of those multiple types. "and / or" includes all combinations of elements, as well as their use individually. When a numerical range is indicated using "~" or "-", it includes both endpoints and has the same unit. For example, 5~25 mol% means between 5 mol% and 25 mol%. "C x-y "C x ~C y " and "C x The notation, such as "...", refers to the number of carbon atoms in the molecule or substituent. For example, C 1-6 Alkyl refers to an alkyl chain having between 1 and 6 carbon atoms (such as methyl, ethyl, propyl, butyl, pentyl, and hexyl). When a polymer has multiple types of repeating units, these repeating units copolymerize. These copolymerizations may be alternating copolymerization, random copolymerization, block copolymerization, graft copolymerization, or a mixture of these. When polymers and resins are shown in structural formulas, the n, m, etc., in parentheses indicate the number of repeating units. The unit of temperature used is Celsius. For example, 20 degrees means 20 degrees Celsius. An additive refers to the compound itself that has the function (for example, in the case of a base generator, it is the compound itself that generates a base). The compound may also be dissolved or dispersed in a solvent and added to the composition. In one embodiment of the present invention, it is preferable that such a solvent is included in the composition according to the present invention as solvent (B) or other component.

[0016] The embodiments of the present invention will be described in detail below.

[0017] <Method for manufacturing thickened resist patterns> The method for producing a thickened resist pattern according to the present invention comprises the following steps. (1) Applying a resist composition to a substrate to form a resist layer from the resist composition; (2a) Exposing the resist layer; (2b) Applying a thickening solution comprising polymer (A) and solvent (B) to the resist layer to form a thickened layer; and (3) Develop the resist layer and the thickened film layer. The following explains each step using diagrams. For clarity, steps (1) and (2) are performed before step (3). The numbers in parentheses indicating the steps indicate the order. However, the order of (2a) and (2b) is arbitrary. The same applies hereafter.

[0018] Step (1) In step (1), the resist composition is applied to the substrate to form a resist layer. Examples of substrates include silicon / silicon dioxide coated substrates, silicon nitride substrates, silicon wafer substrates, glass substrates, and ITO substrates. The resist composition is not particularly limited, but from the viewpoint of forming a fine, high-resolution resist pattern, it is preferably a chemically amplified resist composition, for example, a chemically amplified PHS-acrylate hybrid EUV resist composition. It is also preferable that the resist composition contains a photoacid generator. A preferred resist composition of the present invention is a positive-type chemically amplified resist composition. A typical high-resolution positive resist composition comprises a combination of an alkali-soluble resin, whose side chains are protected by protecting groups, and a photoacid generator. When a resist layer formed from such a composition is irradiated with ultraviolet light, electron beams, extreme ultraviolet light, etc., the photoacid generator releases acid in the irradiated area (exposed area), and this acid 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 the development process. In the case of the present application, where a thickened layer is formed on top of the resist layer, if the region of the underlying resist layer is soluble, both the mixed layer and the resist layer in that region are removed. This will be described later. The resist composition of the present invention can also use a negative-type resist composition. Known negative-type resist compositions and processes can be used. For example, the resist layer and mixed layer in the unexposed areas can be removed together by insolubilizing the polymer with a crosslinking agent or by using an organic solvent in the developer.

[0019] The resist composition is applied to the substrate by an appropriate method. Here, in the present invention, "on top of the substrate" includes application directly on the substrate and application via other layers. For example, a resist underlayer film (e.g., SOC (Spin On Carbon) and / or adhesion-enhancing film) may be formed directly on the substrate, and the resist composition may be applied directly on top of it. Preferably, the resist composition is applied directly on the substrate. In another preferred embodiment, an SOC is formed directly on the substrate, an adhesion-enhancing film is formed directly on top of the SOC, and the resist composition is applied directly on top of them. The application method is not particularly limited, but one example is coating by spin coating. A substrate to which a resist composition has been applied is preferably heated to form a resist layer. This heating is also called pre-baking and is performed, for example, by a hot plate. The heating temperature is preferably 100 to 250°C; more preferably 100 to 200°C; even more preferably 100 to 160°C. Here, the temperature is the heating surface temperature of the hot plate. The heating time is preferably 30 to 300 seconds; more preferably 30 to 120 seconds; even more preferably 45 to 90 seconds. The heating is preferably performed in an atmosphere of air or nitrogen gas; more preferably in an atmosphere of air. Figure 1(i) is a schematic diagram showing a resist layer 2 formed on a substrate 1. The thickness of the resist layer is selected according to the purpose, but is preferably 10 to 100 nm; more preferably 10 to 40 nm; and even more preferably 10 to 30 nm.

[0020] Step (2a) In step (2a), the resist layer is exposed, optionally through a mask. The wavelength of the radiation (light) used for exposure is not particularly limited, but exposure with light having a wavelength 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, wavelength 13.5 nm) can be used. EUV light is more preferred. A range of ±1% in these wavelengths is acceptable. After exposure, post-exposure heating (PEB) can be performed as needed. The PEB temperature can be selected from a range of 70 to 150°C, preferably 80 to 120°C. The PEB heating time can be selected from a range of 0.3 to 5 minutes, preferably 0.5 to 2 minutes. Figure 1(ii) is a schematic diagram showing the state of the resist layer 2 in a case using a typical positive-type chemically amplified resist composition after exposure through a mask. Acid is released from the photoacid generator in the exposed area 4, which deprotects the polymer and increases its alkali solubility. The alkali solubility of the polymer in the unexposed area 3 remains unchanged.

[0021] Step (2b) In step (2b), a thickening solution comprising polymer (A) and solvent (B) is applied to the resist layer to form a thickened layer. In the present invention, the thickening solution is not applied between the resist patterns (after the resist layer has been developed). The application method is not particularly limited, but one example is coating by spin coating. A thickened film layer is formed on a substrate to which a thickened film solution has been applied, preferably by heating or spin-drying (more preferably by heating). Heating is performed, for example, on a hot plate. The heating temperature is preferably 45 to 150°C; more preferably 90 to 130°C. The heating time is preferably 30 to 180 seconds; more preferably 45 to 90 seconds. Heating is preferably performed in an atmosphere of air or nitrogen gas; more preferably in an atmosphere of air. The heating in (2b) is also called mixing bake. The order of (2a) and (2b) is arbitrary. The process of performing (2b) after (2a) is more preferable because it is not necessary to expose while transmitting through the thickened film layer. The process of performing (2a) after (2b) is also possible, in which case it is preferable to perform exposure after controlling the effect of transmitting through the thickened film layer. Figure 1(iii) is a schematic diagram showing a state in which a thickened film layer 5 is formed on the resist layer 2.

[0022] In step (2b), preferably, an insolubilized layer is formed in the vicinity of the contact area between the thickened film layer and the resist layer. Although not bound by theory, it is thought that in the area where the thickened film layer and the resist layer are in contact, the polymers of each layer penetrate each other (intermixing), forming a mixed layer. Whether the mixed layer is soluble or insoluble in the developer in the subsequent developing step depends on whether the underlying resist layer is soluble or insoluble in the developer. If the area of ​​the underlying resist layer is insoluble in the developer, the mixed layer becomes an insolubilized layer. If the area of ​​the underlying resist layer is soluble in the developer, the mixed layer also becomes soluble. Let's explain using the example of a positive-type resist layer. Since the exposed portion of the resist layer is soluble in the developer, the resist layer (matrix component, preferably polymer) that has penetrated the mixed layer in that region dissolves, and the mixed layer also dissolves. The exposed portion of the resist layer below the mixed layer also dissolves. On the other hand, the unexposed portion of the resist layer is insoluble in the developer (for example, it is not deprotected). Therefore, the resist layer that has penetrated the mixed layer in that region is insoluble, and the mixed layer does not dissolve. The unexposed portion of the resist layer below the mixed layer also does not dissolve. Figure 1(iv) is a schematic diagram showing the state in which the insolubilized layer 6 is formed. A mixed layer is also formed in the dissolving region (the exposed area in positive film), but it is not shown in (iv) for simplicity because it is dissolved and removed during the development process.

[0023] In step (2b), it is also preferable to rinse after forming the thickened layer to remove the upper part of the thickened layer (the thickened layer above the mixed layer). The rinse can be one which has the same composition as the solvent (B) of the thickening solution, and preferably water (e.g., DIW) can be used. The rinsing in this invention is different from the development described later. That is, the rinsing is not for dissolving the soluble region of the resist layer to form a resist pattern.

[0024] [Thickening solution] The thickening solution according to the present invention comprises a polymer (A) and a solvent (B), and is used for thickening a resist layer applied before development of the resist layer. The thickening solution according to the present invention is not applied between resist patterns after development. However, the term "development" referred to herein does not include development performed when patterning a resist layer that has already been removed. For example, in the case of a design where multiple resist patterning steps are performed consecutively, it is possible to use the thickening solution of the present invention to thicken the resist layer of a subsequent step, even though it is after development of the resist in the previous step.

[0025] (A) Polymer The polymer (A) used in the present invention is not particularly limited as long as it has good affinity with a resist pattern, and examples thereof include polyacrylic acid and vinyl resins. Preferably, the polymer (A) is a polymer comprising an amino group in a repeating unit. Here, the amino group refers to a primary amino group (-NH2), a secondary amino group (-NHR), and a tertiary amino group (-NRR'). Here, the amino group shall also include those in which nitrogen is bonded to an adjacent element via a double bond, such as -N=. These amino groups may be contained in the side chain of a repeating unit, or may be contained in the main chain structure of the polymer.

[0026] The 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). An embodiment in which the polymer (A) comprises the repeating unit (A1) represented by formula (a1) is more preferable.

[0027] The repeating unit (A1) represented by formula (a1) is as follows.

Chemical Formula

[0028] The repeating unit of P1: polyvinylimidazole, described later, is explained by equation (a1). m11=m12=0. R 11 , R 12 and R 13 L is H. 11 It is a single bond. 14 R is methyl. 15 It is a C3 alkyl (n-propyl) molecule, where one of the -CH2- groups is substituted with -NH-. Furthermore, R 14 alkyl and R 15 The alkyl group is bonded to form an unsaturated heterocycle (imidazole). The repeating unit of P2: polyallylamine, described later, is explained by equation (a1). m11=m12=0. 11 , R 12 and R 13 L is H. 11 R is methylene. 14 and R 15 H is H. The repeating unit of P3: vinylpyrrolidone-vinylimidazole copolymer, described below, is explained by formula (a1). A polymer having (A1) has two types of repeating units, each represented by formula (a1). The vinylimidazole portion is the same as that of P1 described above. The vinylpyrrolidone portion is explained below. m11=m12=0. R 11 , R 12 and R 13 L is H. 11 It is a single bond. 14 It is C2 alkyl(ethyl). 15 It is a C2 acyl (CH3-CO-, acetyl). 14alkyl and R 15 The acyl group is bonded, forming a saturated heterocycle (2-pyrrolidone). The repeating units of the vinylimidazole site and the vinylpyrrolidone site are randomly copolymerized in a 4:6 ratio.

[0029] The repeating units of the polydiallylamine below are explained by equation (a1). m11=m12=1. 11 and R 12 L is H. 11 is methylene, and R 13 R is methyl. 14 It is a single bond, R 13 It binds with R to form a saturated heterocycle. 15 H is H. [ka] The repeating units below are explained by equation (a1). m11=m12=0. R 11 , R 12 and R 13 L is H. 11 It is a single bond. 14 It is C4 alkyl(n-butyl). 15 It is a C2 acyl (CH3-CO-, acetyl). 14 alkyl and R 15 The acyl group is bonded, forming a saturated heterocycle. [ka]

[0030] Examples of polymers having (A1) include polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, and vinylpyrrolidone-vinylimidazole copolymer. Polymer (A) may be a copolymer having two or more types of (A1), for example, vinylpyrrolidone-vinylimidazole copolymer or poly(allylamine-co-diallylamine). Preferably, the polymer having (A1) contains one or two types of repeating units; more preferably, one type. When copolymers are used, preferably the polymer having (A1) contains two types of repeating units.

[0031] The repeating unit (A2) represented by formula (a2) is as follows: [ka] Here, R 21 These are H, single bond, and C, each independently. 1-4 It is alkyl or carboxy(-COOH); preferably H, a single bond or methyl; more preferably H or a single bond; even more preferably H. 21 The single bond is used as a repeating unit to another repeating unit (A2). Single bonds not used at the ends of the polymer may be bonded to H, etc. R 22 , R 23 , R 24 , R 25 These are H and C, respectively, independently. 1-4 It is alkyl or carboxyl; preferably H or methyl; more preferably H. m21 is a number between 0 and 3; preferably 0 or 1; more preferably 1.

[0032] An example of a polymer having (A2) is polyethyleneimine. Polyethyleneimine may be linear or branched; linear is more preferred. Let's explain the linear polyethyleneimine using equation (a2). m21=1, and R 21 , R 22, R 23 , R 24 and R 25 are each H. Branched polyethyleneimine is represented by formula (a2). m21 is 1, and R 21 is H or a single bond. R 22 , R 23 , R 24 and R 25 are each H. Polymer (A) may be a copolymer comprising two or more types of (A2). Preferably, the polymer containing (A2) comprises 1 or 2 types of repeating units; more preferably 1 type. Polymer (A) may be a copolymer comprising (A1) and (A2).

[0033] Polymer (A) can be appropriately selected from the above-described options from the viewpoints of the type of resist composition to be applied, the availability of the polymer, and the like, and is preferably selected from the group consisting of polyvinylimidazole, polyvinylamine, polyallylamine, polydiallylamine, polyethyleneimine, vinylpyrrolidone-vinylimidazole copolymer, and poly(allylamine-co-diallylamine).

[0034] Polymer (A) may be a copolymer comprising repeating units that do not contain an amino group, within a range that does not impair the scope of the present invention. Examples include copolymers containing polyacrylic acid, polymethacrylic acid, polyvinyl alcohol, and the like as copolymerized units.

[0035] Considering the affinity with the polymer in the resist, the content of repeating units not containing an amino group is preferably 50 mol% or less based on the total repeating units constituting Polymer (A); more preferably 30 mol% or less; still more preferably 5 mol% or less. It is also a preferred embodiment of the present invention that the content of repeating units not containing an amino group is 0 mol% (i.e., no such repeating units are contained).

[0036] The mass-average molecular weight of polymer (A) is preferably 5,000 to 200,000; more preferably 5,000 to 150,000; and even more preferably 6,000 to 10,000. In this invention, mass-average molecular weight (Mw) refers to the polystyrene-represented average mass molecular weight measured using gel permeation chromatography.

[0037] The polymer (A) content is preferably 1 to 30% by mass; more preferably 1 to 20% by mass; and even more preferably 2 to 10% by mass, based on the total mass of the thick-film solution. The thick-film forming solution contains polymer (A), but may also contain polymers other than polymer (A) (preferably polymers having repeating units that do not contain amino groups). The content of polymers other than polymer (A) is 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 (no polymer present), based on the total mass of the thick-film forming solution.

[0038] (B) Solvent Solvent (B) is for dissolving polymer (A) and other components as needed. Such a solvent must not dissolve the resist layer. Solvent (B) preferably comprises water. The water is preferably deionized water (DIW). Since it is used to form fine resist patterns, solvent (B) is preferably low in impurities. A preferred solvent (B) has impurities of 1 ppm or less; more preferably 100 ppb or less; and even more preferably 10 ppb or less. Another preferred aspect of the present invention is to prepare a thick-film solution by filtration of the solute solution for use in fine processes. The water content is preferably 80-100% by mass, more preferably 90-100% by mass, even more preferably 98-100% by mass, and even more preferably 100% by mass, based on the total mass of solvent (B). In a preferred embodiment of the present invention, solvent (B) consists substantially of water alone. However, an embodiment in which an additive is dissolved and / or dispersed in a solvent other than water (e.g., a surfactant) and contained in the thick-film forming solution according to the present invention is also acceptable as a preferred embodiment of the present invention.

[0039] Specific examples of solvents (B) other than water include, for example, 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 are preferred in terms of the storage stability of the solution. Two or more of these solvents can be used in combination.

[0040] The content of solvent (B) is preferably 70 to 99% by mass; more preferably 80 to 99% by mass; and even more preferably 90 to 98% by mass, based on the total mass of the thick-film forming solution. The overall pH of the thick-film formation solution is preferably 5 to 12; more preferably 7 to 12; and even more preferably 9 to 12.

[0041] (C) Acid The thick-film solution according to the present invention may further contain an acid (C). Although not bound by theory, it is thought that including an acid (C) makes it possible to adjust the pH of the thick-film solution, which tends to become basic due to the polymer (A). It is thought that this can suppress the dissolution of the polymer in the partially deprotected resist layer present on the surface of the resist layer. Examples of acid (C) include sulfonic acid, carboxylic acid, sulfuric acid, nitric acid, or a mixture of at least two of these; preferably sulfonic acid, sulfuric acid, or nitric acid; more preferably sulfonic acid or nitric acid. Examples of sulfonic acid include p-toluenesulfonic acid, benzenesulfonic acid, p-dodecylbenzenesulfonic acid, 1,4-naphthalenedisulfonic acid, and methanesulfonic acid; preferably p-toluenesulfonic acid. Examples of carboxylic acid include acetic acid, formic acid, oxalic acid, maleic acid, fumaric acid, o-phthalic acid, and succinic acid. The overall pH can be controlled by the amount of acid (C) added. It is preferable not to use strong acids that would denature the resist film as acid (C). For example, it is preferable that the resist film is not deprotected by acid (C).

[0042] The acid (C) content is preferably 0 to 20% by mass; more preferably 0 to 15% by mass; even more preferably 0.1 to 10% by mass; and even more preferably 0.1 to 5% by mass, based on the total mass of the thick-film forming solution. A preferred embodiment of the present invention is that the thick-film forming solution does not contain acid (C) (0% by mass).

[0043] (D) Surfactants The thick-film forming solution according to the present invention may further contain a surfactant (D). Including surfactant (D) can improve the coatability. Examples of surfactants that can be used in the present invention include (I) anionic surfactants, (II) cationic surfactants, or (III) nonionic surfactants, more specifically (I) alkyl sulfonates, alkylbenzene sulfonic acid, and alkylbenzene sulfonates, (II) laurylpyridinium chloride and laurylmethylammonium chloride, and (III) polyoxyethylene octyl ether, polyoxyethylene lauryl ether, polyoxyethylene acetylene glycol ether, fluorine-containing surfactants (e.g., Florard (3M), Megafac (DIC), Sulfuron (Asahi Glass), and organosiloxane surfactants (e.g., KF-53, KP341 (Shin-Etsu Chemical Co., Ltd.)). These surfactants can be used individually or in combination of two or more.

[0044] The content of surfactant (D) is preferably 0 to 5% by mass; more preferably 0.001 to 2% by mass; and even more preferably 0.01 to 1% by mass, based on the total mass of the thick-film-forming solution. The absence of surfactant (D) (0% by mass) is also an embodiment of the present invention.

[0045] (E) Additives The thick-film forming solution according to the present invention may further contain an additive (E) in addition to the components (A) to (D) described above. The additive (E) is preferably a plasticizer, a crosslinking agent, an antibacterial agent, a bactericide, a preservative, an antifungal agent, a base, or a mixture of at least one of these. Preferably, the additive (E) comprises a base; more preferably, it consists of a base. Unlike polymer (A) which contains an amino group, the base 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 having a cage-like three-dimensional structure. 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-propylenediamine, N,N,N',N'-tetraethyl-1,2-propylenediamine, and N,N,N',N'-tetramethyl-1,2-propylenediamine. Trapropyl-1,2-propylenediamine, N,N,N',N'-tetraisopropyl-1,2-propylenediamine, N,N,N',N'-tetramethyl-1,3-propylenediamine, N,N,N',N'-tetraethyl-1,3-propylenediamine, N,N,N',N'-tetrapropyl-1,3-propylenediamine, N,N,N',N'-tetraisopropyl-1,3-propylenediamine, N,N,N ',N'-tetramethyl-1,2-butylenediamine, N,N,N',N'-tetraethyl-1,2-butylenediamine, N,N,N',N'-tetrapropyl-1,2-butylenediamine, N,N,N',N'-tetraisopropyl-1,2-butylenediamine, N,N,N',N'-tetramethyl-1,3-butylenediamine, N,N,N',N'-tetraethyl-1,3-butylenediamine, N,N,N',N' Examples include N,N,N',N'-tetraisopropyl-1,3-butylenediamine, N,N,N',N'-tetramethyl-1,4-butylenediamine, N,N,N',N'-tetraethyl-1,4-butylenediamine, N,N,N',N'-tetrapropyl-1,4-butylenediamine, and N,N,N',N'-tetraisopropyl-1,4-butylenediamine. Examples of amine compounds having a cage-like three-dimensional structure include 1,4-diazabicyclo[2.2.2]octane, 2-methyl-1,4-diazabicyclo[2.2.2]octane, 1,4-diazabicyclo[2.2.2]octan-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. In a preferred embodiment of the present invention, the base of additive (E) is 1,4-diazabicyclo[2.2.2]octane. Although not bound by theory, it is thought that the inclusion of the base of additive (E) promotes the penetration of the thick-film solution into the resist layer, causing the underlying resist layer to expand further.

[0046] The content of additive (E) is preferably 0 to 10% by mass; more preferably 0.001 to 5% by mass; even more preferably 0.01 to 4% by mass; and even more preferably 0.1 to 3% by mass, based on the total mass of the thick-film-forming solution. A preferred embodiment of the present invention is that the thick-film-forming solution according to the present invention does not contain additive (E) (0% by mass).

[0047] Step (3) In step (3), the resist layer and the thickened layer are developed. Methods for applying the developer include, for example, the paddle method, the dip method, and the spray method. The developer temperature is preferably 5 to 50°C; more preferably 25 to 40°C, and the development time is preferably 15 to 120 seconds; more preferably 30 to 60 seconds. After application of the developer, it is removed. The resist pattern after development can also be rinsed. Rinsing can preferably be done with water (DIW). The developing solution is preferably an alkaline aqueous solution or an organic solvent; more preferably an alkaline aqueous solution. Examples of alkaline aqueous solutions include aqueous solutions containing inorganic alkalis 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 an aqueous TMAH solution; and even more preferably a 2.38% by mass TMAH aqueous solution. The developer can also be further enriched by adding the surfactants mentioned above.

[0048] Figure 1(v) shows the state in which the developer solution has been applied to the resist layer and the thickened layer, the developer solution has been removed, and the thickened resist pattern 7 has been formed. If the amount of thickening is defined as (height of the thickened resist pattern) - (height of a resist pattern formed similarly except that the thickening solution is not applied), then the amount of thickening is preferably 2 to 20 nm; more preferably 2 to 15 nm; even more preferably 3 to 10 nm; and even more preferably 3 to 8 nm. Although not bound by theory, in high-resolution lithography techniques such as EUV exposure, the thickness of the resist film is generally thin. However, by thickening the film according to the present invention, it is considered possible to ensure durability as a mask when used in a later process, for example, as an etching mask.

[0049] <Manufacturing methods for processed substrates and devices> The method for manufacturing a processed substrate according to the present invention comprises the following steps. Forming the thickened resist pattern described above; and (4) Processing using a thickened resist pattern as a mask.

[0050] Step (4) In step (4), the thickened resist pattern is used as a mask for processing. The thickened resist pattern is preferably used for processing the resist underlayer or substrate (more preferably the substrate). Specifically, the resist pattern can be used as a mask to process various substrates using methods such as dry etching, wet etching, ion implantation, and metal plating. Because the resist pattern is thickened, it can function as a mask even under more stringent conditions, making it suitable for processing by dry etching. When processing the resist underlayer using a thickened resist pattern, the processing may be carried out in steps. For example, the resist pattern may be used to process the adhesion-enhancing film and the SOC, and the SOC pattern may be used to process the substrate. For example, SiARC (Si anti-reflective coating) can be used as the adhesion-enhancing film.

[0051] A method for manufacturing a 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 processing methods can be performed using known methods. Subsequently, the substrate is cut into chips as needed, connected to a lead frame, and packaged with resin. In the present invention, this packaged product 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. The device is preferably a semiconductor element. [Examples]

[0052] The present invention will be described below with reference to various examples. However, the embodiments of the present invention are not limited to these examples.

[0053] [Preparation of thick-film forming solutions 1-3] The polymer (A), surfactant (D), and base (E) listed in Table 1 are dissolved in solvent (B). The respective amounts are as shown in Table 1. The values ​​in Table 1 represent the content (mass%) of each component relative to the total mass of the thick-film solution. The obtained solution is stirred at room temperature for 60 minutes. After visually confirming that the solute is completely dissolved, the solution is filtered through a 0.2 μm fluorine resin filter to obtain thick-film solutions 1 to 3. [Table 1] In the table, P1: Polyvinylimidazole (Mw 30,000) [ka] • P2: Polyallylamine (Mw 8,000) [ka] P3: Vinylpyrrolidone, vinylimidazole, random copolymer (m:n=4:6, Mw 25,000) [ka] • S1: An acetylene-based diol polyoxyalkylene ether having the following structure. [ka]

[0054] [Example 1] A silicon substrate is treated with HMDS (hexamethyldisilazane) at 90°C for 30 seconds. A chemically amplified PHS-acrylate hybrid resist composition (positive type) is applied to the HMDS-treated substrate by spin coating and heated on a hot plate at 110°C for 60 seconds to form a resist layer with a thickness of 35 nm. The resist layer is exposed using an EUV lithography apparatus (NXE:3300B, ASML) through an 18 nm (line:space = 1:1) mask while varying the exposure amount. After that, post-exposure heating (PEB) is performed at 100°C for 60 seconds. Then, thickening solution 1 is applied on top of the resist layer by spin coating to form a thickened layer and heated at 130°C for 60 seconds. After that, paddle development is performed for 30 seconds using a 2.38 mass% TMAH aqueous solution as the developer. Water is then added dropwise while the developer is paddled on the substrate, and the water is added dropwise while rotating the substrate to replace the developer with water. Afterward, the substrate is rotated at high speed to dry the thickened resist pattern of Example 1.

[0055] For comparison, a resist pattern is formed without the application of the thickening solution. Specifically, the resist pattern is formed in the same manner as in Example 1, except that the thickening solution is not applied and the subsequent heating is not performed. This is called the comparative resist pattern.

[0056] [evaluation] For the thickened resist pattern of Example 1 and the comparison resist pattern, substrate sections were prepared, and the cross-sectional shapes were observed using a SEM (SU8230, Hitachi High-Tech Fieldings), and the pattern heights were measured. The amount of thickening was calculated as (height of thickened resist pattern) - (height of comparison resist pattern). The obtained results are shown in Table 2. Examples 2 and 3 are conducted in the same manner as in Example 1, except that the type of thickening solution is changed to one of those listed in Table 2, and the amount of thickened film is calculated. The results obtained are shown in Table 2. [Table 2] [Explanation of Symbols]

[0057] 1. Circuit board 2. Resist layer 3. Unexposed areas 4. Exposure area 5.Thickened layer 6. Immobilization layer 7. Thickened resist pattern 8. Height of the thickened resist pattern

Claims

1. A method for producing a thickened resist pattern, comprising the following steps. (1) Applying a resist composition to a substrate to form a resist layer from the resist composition; (2a) Exposing the resist layer; (2b) Applying a thickening solution comprising polymer (A) and solvent (B) to the resist layer to form a thickened layer, and rinsing after the formation of the thickened layer to remove the upper part of the thickened layer; and (3) Developing the resist layer and the thickened layer; In step (2b), an insolubilization layer is formed in the vicinity of the area where the thickened film layer and the resist layer are in contact.

2. The method according to claim 1, wherein the upper part of the thickened film layer is a thickened film layer above the insolubilized layer.

3. The method according to claim 1 or 2, wherein the polymer (A) is a polymer containing amino groups in repeating units.

4. The method according to 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). 【Chemistry 1】 Here, R １１ , R １２ and R １３ These are H and C, respectively, independently. １－４ Alkyl or carboxyl, L １１ is a single bond or C １－４ It is alkylene, R １４ These are single bonds, H or C １－５ It is alkyl, R １５ represents H, C １－５ alkyl, C １－５ acyl, or formyl, wherein L １１ 's alkyl, R １４ 's alkyl, and R １５ 's -CH in alkyl or acyl ２ - at least one of which may each independently be substituted with -NH-, R １４ 's single bond or alkyl and R １３ 's alkyl may be bonded together to form a saturated or unsaturated heterocyclic ring, R １４ Alkyl and R １５ The alkyl, acyl, or formyl may be bonded together to form a saturated or unsaturated heterocycle. m11 and m12 are independently numbers between 0 and 1. 【Chemistry 2】 Here, R ２１ These are H, single bond, and C, each independently. １－４ Alkyl or carboxyl, R ２２ , R ２３ , R ２４ , R ２５ These are H and C, respectively, independently. １－４ Alkyl or carboxyl, m21 is a number between 0 and 3.

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

6. The solvent (B) comprises water, The water content is 80 to 100% by mass, based on the total mass of the solvent (B); The content of the polymer (A) is 1 to 30% by mass, based on the total mass of the thick-film solution; or The method according to claim 1 or 2, wherein the content of the solvent (B) is 70 to 99% by mass, based on the total mass of the thick-film solution.

7. The aforementioned thick-film forming solution further comprises an acid (C), The method according to claim 1 or 2, wherein the content of the acid (C) is 0 to 20% by mass, based on the total mass of the thick-film solution.

8. The method according to claim 7, wherein the pH of the entire thick-film-forming solution is 5 to 12.

9. The method according to claim 7, wherein the acid (C) is a sulfonic acid, a carboxylic acid, sulfuric acid, nitric acid, or a mixture of at least two of these.

10. The aforementioned thick-film-forming solution further comprises a surfactant (D), The method according to claim 1 or 2, wherein the content of the surfactant (D) is 0 to 5% by mass based on the total mass of the thick-film-forming solution.

11. The aforementioned thick-film solution further comprises an additive (E), The method according to claim 1 or 2, wherein the additive (E) is a plasticizer, a crosslinking agent, an antibacterial agent, a bactericide, a preservative, an antifungal agent, a base, or a mixture of at least some of these.

12. The method according to claim 11, wherein the content of the additive (E) is 0 to 10% by mass based on the total mass of the thickening solution.

13. The method according to claim 1 or 2, wherein the resist composition is a chemically amplified resist composition.

14. The method according to claim 13, wherein the resist composition further comprises a photoacid generator.

15. A method for manufacturing a processed substrate, comprising the following steps. To form a thickened resist pattern according to claim 1 or 2; and (4) Processing using the thickened resist pattern as a mask.

16. A method for manufacturing a device comprising the method of claim 15, further comprising the step of forming wiring on a processed substrate.

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