Vertically phase-separated block copolymer layer

Abstract

The present invention provides: a layer containing a block copolymer in which a microphase-separated structure of the block copolymer has been induced to be perpendicular to a substrate, said process being difficult to perform by means of heating at atmospheric pressure; a method for producing this layer; and a method for producing a semiconductor device in which a vertically phase-separated block copolymer layer is used.　A vertically phase-separated block copolymer layer which is formed by means of heating at a pressure below atmospheric pressure and at a temperature at which induced self-assembly can occur. It is preferable that the vertical phase separation comprises a lamellar portion. It is preferable that the lamellar portion comprises PMMA. It is preferable that the heating temperature is 290°C or higher. It is preferable to additionally have a layer, which neutralizes the surface energy of the block copolymer, beneath the block copolymer layer.

Description

[Technical Field]

[0001] The present invention relates to a vertically phase-separated block copolymer layer (e.g., a diblock copolymer layer, a triblock copolymer layer, or a tetrablock copolymer layer), preferably a vertically phase-separated polystyrene-block (hereinafter abbreviated as "b")-polymethyl methacrylate (PS-b-PMMA), utilizing self-assembly technology for block copolymers in the field of semiconductor lithography, a method for producing the layer, and a method for producing a semiconductor device using the vertically phase-separated block copolymer layer, preferably a PS-b-PMMA layer. [Background technology]

[0002] In recent years, with the further miniaturization of large-scale integrated circuits (LSIs), there has been a demand for technologies to process more delicate structures. To meet this demand, pattern formation technologies that utilize phase separation structures formed by the self-assembly of block copolymers, which are composed of mutually immiscible polymers, are being put into practical use to form finer patterns. For example, a pattern formation method has been proposed in which a self-assembled film containing a block copolymer, in which two or more polymers are bonded, is formed on the surface of a substrate, and the block copolymer in the self-assembled film is phase-separated, selectively removing the phase of at least one polymer constituting the block copolymer. Patent Document 1 discloses a composition for forming an underlayer of a self-assembled film containing a polycyclic aromatic vinyl compound. Non-Patent Document 1 discloses a technology for inducing self-assembly of a self-assembled film by reducing the oxygen concentration of the atmosphere. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2014 / 097993 [Non-patent literature]

[0004] [Non-Patent Document 1] Nathalie Frolet et al., “Expanding DSA process window with atmospheric control”, Proc. of SPIE Vol.11326 113261J-1~J-6(2020) [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a layer containing a block copolymer, preferably PS-b-PMMA, in which a microphase separation structure of the block copolymer, preferably PS-b-PMMA, is induced perpendicularly to the substrate without causing misalignment, a method for producing the same, and a method for producing a semiconductor device using a vertically phase-separated block copolymer (preferably PS-b-PMMA) layer, which is difficult to achieve by heating under atmospheric pressure. [Means for solving the problem]

[0006] This invention encompasses the following: [1] A vertically phase-separated block copolymer layer formed by heating at a temperature at which induced self-assembly can occur under pressures below atmospheric pressure. [2] The vertically phase-separated block copolymer layer according to [1], wherein the block copolymer is PS-b-PMMA. [3] The vertically phase-separated block copolymer layer according to [1] or [2], wherein the vertical phase separation includes a lamellar-shaped portion. [4] A vertically phase-separated block copolymer layer according to any one of [1] to [3], wherein the heating temperature is 290°C or higher. [5] A vertically phase-separated block copolymer layer according to any one of [1] to [4], further comprising a block copolymer layer having a neutralized surface energy layer of the block copolymer below the block copolymer layer. [6] The vertically phase-separated block copolymer layer according to [5], wherein the neutralized layer comprises a polymer having a unit structure derived from an aromatic compound. [7] The vertically phase-separated block copolymer layer according to [6], comprising 50 mol% or more of the unit structure derived from the aromatic compound with respect to the entire polymer. [8] The vertically phase-separated block copolymer layer according to [5], wherein the neutralized layer comprises a polymer having a unit structure in which the aliphatic polycyclic structure of an aliphatic polycyclic compound is included in the main chain. [9] The neutralized layer comprises a vertically phase-separated block copolymer layer as described in [5], wherein the neutralized layer contains a polysiloxane.

[10] The neutralized layer is a vertically phase-separated block copolymer layer according to any one of [5] to [7], comprising a polymer having reactive substituents at its ends.

[11] A vertically phase-separated block copolymer layer formed on a substrate, as described in any one of items [1] to [9].

[12] A method for producing a vertically phase-separated block copolymer layer, A method for producing a vertically phase-separated block copolymer layer, comprising the steps of forming a block copolymer layer on a substrate, and then heating the substrate at a pressure below atmospheric pressure.

[13] A method for manufacturing a semiconductor device, comprising the steps of: forming a block copolymer layer on a substrate; heating the substrate at a pressure below atmospheric pressure; etching the vertically phase-separated block copolymer layer; and etching the substrate. [Effects of the Invention]

[0007] The vertically phase-separated block copolymer layer of the present application, preferably the PS-b-PMMA layer, is obtained by heating the block copolymer layer before phase separation, preferably the PS-b-PMMA layer, under a pressure less than atmospheric pressure, so that the block copolymer, preferably PS-b-PMMA, is induced to self-organize, and a vertically phase-separated block copolymer layer, preferably a PS-b-PMMA layer (which may be a layer containing PS-b-PMMA, but preferably a layer containing only PS-b-PMMA), is induced to have a microphase separation structure perpendicular to the substrate. Preferably, it is a block copolymer layer having at least a lamellar shape (i.e., it may contain one or more lamellar shapes), preferably a PS-b-PMMA layer, preferably a block copolymer layer having a lamellar shape, preferably a PS-b-PMMA layer. By selectively etching the vertically phase-separated block copolymer layer, preferably the layer containing PS-b-PMMA, the semiconductor substrate can be processed to manufacture a semiconductor device.

Brief Description of the Drawings

[0008] [Figure 1] It is a schematic diagram showing the state of PS-b-PMMA induced self-organization. [Figure 2] It is a schematic diagram showing a substrate, a lower layer film layer (the neutralization layer referred to in the present application), and a self-organization layer (the PS-b-PMMA layer referred to in the present application). [Figure 3] It is an electron micrograph exemplifying the "vertical alignment" and "alignment defect" referred to in the present application.

Embodiments for Carrying Out the Invention

[0009] <Vertically Phase-Separated Block Copolymer Layer> The vertically phase-separated block copolymer layer of the present application, preferably the PS-b-PMMA layer, can be formed by coating a known block copolymer layer, preferably a block copolymer layer-forming composition containing PS-b-PMMA, preferably a PS-b-PMMA layer-forming composition, on a substrate and heating it under a pressure less than atmospheric pressure.

[0010] The above-mentioned vertical phase separation may occur in at least a portion of the block copolymer layer, preferably the PS-b-PMMA layer, but preferably, it is preferable that the vertical phase separation occurs throughout the entire block copolymer layer, preferably the PS-b-PMMA layer (the area where vertical phase separation occurs is 80% or more, more preferably 90% or more, even more preferably 95% or more, and most preferably 100% of the entire surface to which the block copolymer layer, preferably the PS-b-PMMA layer, is coated). The area where vertical phase separation occurs can be determined from the average value of the area where vertical phase separation occurs in the observed image obtained by electron microscopy observation from three or more locations on the upper surface of a portion of the substrate surface after the phase separation process. As shown in the example electron micrograph in Figure 3, if there is a misaligned portion in the observed image obtained by electron microscopy observation from the upper surface of a portion of the substrate surface after the phase separation process, it can be determined that there is a misalignment.

[0011] The diblock copolymer PS-b-PMMA can be manufactured by known methods. Commercially available products may also be used.

[0012] Furthermore, the block copolymer may be a block copolymer obtained by bonding a silicon-free polymer or a silicon-free polymer having a structure derived from lactide as a constituent unit, which may be substituted with an organic group, with a silicon-containing polymer having a structure derived from styrene as a constituent unit.

[0013] Among these, a combination of a silylated polystyrene derivative and a polystyrene derivative polymer, or a combination of a silylated polystyrene derivative polymer and polylactide is preferred.

[0014] Among these, a combination of a silylated polystyrene derivative having a substituent at the 4-position and a polystyrene derivative polymer having a substituent at the 4-position, or a combination of a silylated polystyrene derivative polymer having a substituent at the 4-position and polylactide is preferred.

[0015] More preferred specific examples of block copolymers include combinations of poly(trimethylsilylstyrene) and polymethoxystyrene, combinations of polystyrene and poly(trimethylsilylstyrene), and combinations of poly(trimethylsilylstyrene) and poly(D,L-lactide).

[0016] More preferred specific examples of block copolymers include combinations of poly(4-trimethylsilylstyrene) and poly(4-methoxystyrene), combinations of polystyrene and poly(4-trimethylsilylstyrene), and combinations of poly(4-trimethylsilylstyrene) and poly(D,L-lactide). The most preferred specific examples of block copolymers include poly(4-methoxystyrene) / poly(4-trimethylsilylstyrene) copolymer and polystyrene / poly(4-trimethylsilylstyrene) copolymer. The full disclosure contained in Publication No. WO2018 / 135456 is incorporated herein by reference.

[0017] Furthermore, the block copolymer is a block copolymer formed by bonding a silicon-free polymer with a silicon-containing polymer whose constituent unit is styrene substituted with a silicon-containing group, and the silicon-free polymer may be a block copolymer containing a unit structure represented by the following formula (1-1c) or formula (1-2c). [ka] (In formula (1-1c) or formula (1-2c), R 1 and R 2 Each of these independently represents a hydrogen atom, a halogen atom, and an alkyl group having 1 to 10 carbon atoms, and R 3 ~R 5 Each of these independently represents a hydrogen atom, a hydroxyl group, a halogen atom, a C1-C10 alkyl group, a C1-C10 alkoxy group, a cyano group, an amino group, an amide group, or a carbonyl group.

[0018] The silicon-containing group described above may contain one silicon atom. The silicon-containing polymer described above may include a unit structure represented by the following formula (2c). [ka] (In formula (2c), R 6 ~R 8 Each of these independently represents an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 40 carbon atoms.

[0019] Furthermore, as the block copolymer, a block copolymer described in Japanese Patent Publication 2019-507815, including [BCP1] to [BCP4] below, may be used. [BCP1]5-vinylbenzo[d][1,3]dioxole-containing block copolymer. [BCP2] The block copolymer according to [BCP1], wherein the block copolymer further comprises a block containing silicon. [BCP3] The block copolymer according to [BCP2], further comprising pentamethyldisilylstyrene. [BCP4] The block copolymer according to [BCP3], wherein the block copolymer is poly(5-vinylbenzo[d][1,3]dioxole)-b-poly(pentamethyldisilylstyrene).

[0020] The synthesis of the poly(5-vinylbenzo[d][1,3]dioxol-block-4-pentamethyldisilylstyrene) described above is shown in Scheme 1 below. [ka]

[0021] Preferably, the silicon-containing polymer or silicon-containing block is poly(4-trimethylsilylstyrene) derived from 4-trimethylsilylstyrene. Preferably, the silicon-containing polymer or silicon-containing block is poly(pentamethyldisilylstyrene) derived from pentamethyldisilylstyrene. The aryl group having 6 to 40 carbon atoms means a monovalent group of a monocyclic or polycyclic aromatic hydrocarbon having 6 to 40 carbon atoms, and specific examples include a phenyl group, a naphthyl group, or anthryl group. The full disclosure described in WO2020 / 017494 is incorporated herein by reference.

[0022] In addition, block copolymers consisting of the monomer combinations listed below may be used: styrene, methyl methacrylate, dimethylsiloxane, propylene oxide, ethylene oxide, vinylpyridine, vinylnaphthalene, D,L-lactide, methoxystyrene, methylenedioxystyrene, trimethylsilylstyrene, pentamethyldisilylstyrene.

[0023] Useful block copolymers may be copolymers such as diblocks, triblocks, or tetrablocks having at least two blocks, each of which may be a homopolymer or a random or alternating copolymer.

[0024] Typical block copolymers include polystyrene-β-polyvinylpyridine, polystyrene-β-polybutadiene, polystyrene-β-polyisoprene, polystyrene-β-polymethyl methacrylate, polystyrene-β-polyalkenyl aromatics, polyisoprene-β-polyethylene oxide, polystyrene-β-poly(ethylene-propylene), polyethylene oxide-β-polycaprolactone, polybutadiene-β-polyethylene oxide, polystyrene-β-poly((meth)acrylate t-butyl), polymethyl methacrylate-β-poly(methacrylate t-butyl), polyethylene oxide-β-polypropylene oxide, and polystyrene-β-polytetra Examples include hydrofuran, polystyrene-b-polyisoprene-b-polyethylene oxide, poly(styrene-b-dimethylsiloxane), poly(methyl methacrylate-b-dimethylsiloxane), poly((methyl meth)acrylate-r-styrene)-b-polymethyl methacrylate, poly((methyl meth)acrylate-r-styrene)-b-polystyrene, poly(p-hydroxystyrene-r-styrene)-b-polymethyl methacrylate, poly(p-hydroxystyrene-r-styrene)-b-polyethylene oxide, polyisoprene-b-polystyrene-b-polyferrocenylsilane, or combinations containing at least one of the block copolymers described above.

[0025] Furthermore, block copolymers consisting of combinations of organic polymers and / or metal-containing polymers as described below are also exemplified.

[0026] Typical organic polymers include poly(9,9-bis(6'-N,N,N-trimethylammonium)-hexyl)-fluorenphenylene) (PEP), poly(4-vinylpyridine) (4PVP), hydroxypropyl methylcellulose (HPMC), polyethylene glycol (PEG), poly(ethylene oxide)-poly(propylene oxide) diblock or multiblock copolymer, polyvinyl alcohol (PVA), poly(ethylene-vinyl alcohol) (PEVA), polyacrylic acid (PAA), polylactic acid (PLA), poly(ethyl oxazoline), poly(alkyl acrylate), and polyacrylic acid. This includes, but is not limited to, luamide, poly(N-alkylacrylamide), poly(N,N-dialkylacrylamide), polypropylene glycol (PPG), polypropylene oxide (PPO), partially or entirely hydrogenated poly(vinyl alcohol), dextran, polystyrene (PS), polyethylene (PE), polypropylene (PP), polyisoprene (PI), polychloroprene (CR), polyvinyl ether (PVE), polyvinyl acetate (PVA), polyvinyl chloride (PVC), polyurethane (PU), polyacrylate, polymethacrylate, oligosaccharides, or polysaccharides.

[0027] Metal-containing polymers include, but are not limited to, silicon-containing polymers—for example, polydimethylsiloxane (PDMS), cage-type silsesquiosan (POSS), or poly(trimethylsilistyrene) (PTMSS)—or silicon and iron-containing polymers—for example, poly(ferrocenyldimethylsilane) (PFS)—.

[0028] Typical block copolymers include, but are not limited to, diblock copolymers—for example, polystyrene-b-polydimethylsiloxane (PS-PDMS), poly(2-vinylpropylene)-b-polydimethylsiloxane (P2VP-PDMS), polystyrene-b-poly(ferrocenyldimethylsilane) (PS-PFS), or polystyrene-b-polyDL-lactic acid (PS-PLA)—or triblock copolymers—for example, polystyrene-b-poly(ferrocenyldimethylsilane)-b-poly(2-vinylpyridine) (PS-PFS-P2VP), polyisoprene-b-polystyrene-b-poly(ferrocenyldimethylsilane) (PI-PS-PFS), or polystyrene-b-poly(ferrocenyldimethylsilane)-b-polystyrene (PS-PTMSS-PS)—. In one embodiment, the PS-PTMSS-PS block copolymer comprises a poly(trimethylsilistyrene) polymer block composed of two chains of PTMSS connected by a linker containing four styrene units. Modified forms of the block copolymer are also conceivable, such as those disclosed in U.S. Patent Application Publication No. 2012 / 0046415.

[0029] Other block copolymers include, for example, block copolymers formed by bonding a polymer composed of styrene or its derivatives with a polymer composed of (meth)acrylic acid esters, block copolymers formed by bonding a polymer composed of styrene or its derivatives with a polymer composed of siloxane or its derivatives, and block copolymers formed by bonding an alkylene oxide polymer with a polymer composed of (meth)acrylic acid esters. Note that "(meth)acrylic acid ester" refers to either or both of acrylic acid esters with a hydrogen atom bonded at the α-position and methacrylic acid esters with a methyl group bonded at the α-position.

[0030] Examples of (meth)acrylic acid esters include those in which substituents such as alkyl groups or hydroxyalkyl groups are bonded to the carbon atoms of (meth)acrylic acid. Examples of alkyl groups used as substituents include linear, branched, or cyclic alkyl groups having 1 to 10 carbon atoms. Specific examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, benzyl (meth)acrylate, anthracene (meth)acrylate, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethane (meth)acrylate, and propyltrimethoxysilane (meth)acrylate.

[0031] Examples of styrene derivatives include α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-t-butylstyrene, 4-n-octylstyrene, 2,4,6-trimethylstyrene, 4-methoxystyrene, 4-t-butoxystyrene, 4-hydroxystyrene, 4-nitrostyrene, 3-nitrostyrene, 4-chlorostyrene, 4-fluorostyrene, 4-acetoxyvinylstyrene, vinylcyclohexane, 4-vinylbenzyl chloride, 1-vinylnaphthalene, 4-vinylbiphenyl, 1-vinyl-2-pyrrolidone, 9-vinylanthracene, and vinylpyridine.

[0032] Examples of siloxane derivatives include dimethylsiloxane, diethylsiloxane, diphenylsiloxane, and methylphenylsiloxane. Examples of alkylene oxides include ethylene oxide, propylene oxide, isopropylene oxide, and butylene oxide.

[0033] Examples of the aforementioned block copolymers include styrene-polyethyl methacrylate block copolymer, styrene-(poly-t-butyl methacrylate) block copolymer, styrene-polymethacrylate block copolymer, styrene-polymethyl acrylate block copolymer, styrene-polyethyl acrylate block copolymer, styrene-(poly-t-butyl acrylate) block copolymer, and styrene-polyacrylic acid block copolymer.

[0034] One method for synthesizing block copolymers involves living radical polymerization, living cationic polymerization, or living anionic polymerization, where the polymerization process consists only of an initiation reaction and a growth reaction, without side reactions that deactivate the growth ends. The growth ends can maintain their growth activity during the polymerization reaction. By preventing chain transfer, polymers of uniform length (A) can be obtained. By adding a different monomer (b) using the growth ends of this polymer (A), polymerization can proceed with this monomer (b) to form a block copolymer (AB).

[0035] For example, if there are two types of blocks, A and B, the molar ratio of polymer chain (A) to polymer chain (B) can be 1:9 to 9:1, preferably 3:7 to 7:3.

[0036] The volume ratio of the block copolymer used in the present invention is, for example, 30:70 to 70:30. Homopolymer A or B is a polymerizable compound having at least one radically polymerizable reactive group (vinyl group or vinyl group-containing organic group).

[0037] The weight-average molecular weight Mw of the block copolymer used in the present invention is preferably 1,000 to 100,000, or 5,000 to 100,000. If it is less than 1,000, the coating properties to the substrate may be poor, and if it is 100,000 or more, the solubility in the solvent may be poor.

[0038] The polydispersity (Mw / Mn) of the block copolymer of this application is preferably 1.00 to 1.50, and particularly preferably 1.00 to 1.20.

[0039] In one embodiment of the present invention, the block copolymer is PS-b-PMMA.

[0040] The block copolymer layer-forming composition of this application (preferably the PS-b-PMMA layer-forming composition) may have a solid content of 0.1 to 10% by mass, or 0.1 to 5% by mass, or 0.1 to 3% by mass. The solid content is the proportion remaining after removing the solvent from the block copolymer layer-forming composition (preferably the PS-b-PMMA layer-forming composition).

[0041] The proportion of block copolymer in the solid content can be 30-100% by mass, 50-100% by mass, 50-90% by mass, or 50-80% by mass.

[0042] <Solvent> The solvent contained in the block copolymer layer-forming composition, preferably the PS-b-PMMA layer-forming composition, as referred to in this application is not particularly limited as long as it is a solvent that can dissolve the block copolymer, preferably PS-b-PMMA, but it is preferably an organic solvent used in semiconductor lithography processes. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, and cyclo Examples include loheptanone, 4-methyl-2-pentanol, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, ethyl ethoxyacetate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents can be used individually or in combination of two or more.

[0043] Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, butyl acetate, methyl isobutyl ketone, and cyclohexanone are preferred. Propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate are particularly preferred.

[0044] In addition, the solvent contained in the block copolymer layer-forming composition, preferably the PS-b-PMMA layer-forming composition, may be a combination of a low-boiling-point solvent (A) with a boiling point of 160°C or less and a high-boiling-point solvent (B) with a boiling point of 170°C or more, as described in WO2018 / 135456.

[0045] The above composition may contain 0.3 to 2.0% by weight of the high-boiling point solvent (B) relative to the total amount of solvent.

[0046] As a low-boiling point solvent (A) with a boiling point of 160°C or less, for example, propylene glycol monomethyl ether acetate (boiling point: 146°C), n-butyl acetate (boiling point: 126°C), and methyl isobutyl ketone (boiling point: 116°C) are preferred.

[0047] As a high-boiling point solvent (B) with a boiling point of 170°C or higher, for example, N-methylpyrrolidone (boiling point: 204°C), diethylene glycol monomethyl ether (boiling point: 193°C), N,N-dimethylisobutylamide (boiling point: 175°C), 3-methoxy-N,N-dimethylpropanamide (boiling point: 215°C), and γ-butyrolactone (boiling point: 204°C) are preferred.

[0048] Low-boiling point solvent (A) and high-boiling point solvent (B) can each be selected from two or more types and mixed. In a preferred embodiment, the composition contains 0.3 to 2.0% by weight of the high-boiling point solvent (B) relative to the total amount of solvent in the composition. Most preferably, the composition contains 0.5 to 1.5% by weight of the high-boiling point solvent (B).

[0049] The atmospheric pressure mentioned above is 760,000 mTorr. "Less than atmospheric pressure" is not particularly limited as long as it is less than 760,000 mTorr, but it is preferable that it is, for example, 500,000 mTorr or less, 300,000 mTorr or less, 100,000 mTorr or less, 50,000 mTorr or less, 30,000 mTorr or less, 20,000 mTorr or less, 10,000 mTorr or less, 9,000 mTorr or less, 8,000 mTorr or less, 7,000 mTorr or less, 6,000 mTorr or less, 5,000 mTorr or less, 4,000 mTorr or less, 3,000 mTorr or less, 2,000 mTorr or less, 1,000 mTorr or less, 900 mTorr or less, and 800 mTorr or less. For example, values ​​of 10,000 to 10 mTorr, 1,000 to 50 mTorr, and 800 to 50 mTorr are preferable.

[0050] The gas present in the atmosphere at pressures below atmospheric pressure (the atmosphere during the induced self-assembly of the block copolymer, preferably PS-b-PMMA) is not particularly limited. It may be air, an N2 / O2 mixed gas (the mixing ratio is arbitrary), N2 gas alone, or O2 gas alone. Other gases that do not affect the induced self-assembly (vertical phase separation) of the block copolymer, preferably PS-b-PMMA, may also be present.

[0051] The heating described above is a heat treatment performed on a film formed by coating a block copolymer, preferably PS-b-PMMA, onto the upper surface of a typically flat semiconductor substrate (such as a silicon wafer), as detailed below. The heating is performed at a temperature at which induced self-assembly can occur. The heating temperature is usually between 230°C and 350°C, but 290°C or higher is preferred. In another embodiment, the heating temperature is preferably between 260°C and 340°C, 290°C and 330°C, or 290°C and 320°C. The heating time is usually between 1 minute and 1 hour, but may be between 2 minutes and 30 minutes or between 3 minutes and 10 minutes.

[0052] For example, at high temperatures above 300°C (300°C to 330°C), vertical phase separation can be achieved in relatively short periods of time, such as 1 to 10 minutes, 1 to 5 minutes, or 1 to 3 minutes.

[0053] Preferably, the vertical phase separation includes lamellar-shaped portions. In this specification, lamellar shape is used in the common sense of the art, and for example, in the case of a diblock copolymer AB (where AB represents each block portion), it has a structure in which AB alternately self-assembles (self-assembles) in the form of ...ABBAABBAAB.... The lamellar shape has a structure in which films are stacked in parallel. In some embodiments, the lamellar shape has a so-called fingerprint structure.

[0054] In the above PS-b-PMMA, the weight-average molecular weights of PS and PMMA are, for example, in the range of 10,000 to 100,000 for PS and 10,000 to 100,000 for PMMA. It is preferable to use PS with a larger weight-average molecular weight compared to PMMA. The weight-average molecular weight ratio of PS to PMMA (PS / PMMA ratio) is, for example, 5.0 to 0.1, 3.0 to 0.5, 2.0 to 0.6, 1.5 to 0.7, 1.2 to 0.8, 1.1 to 0.9, and 1.0.

[0055] Figure 1 shows a schematic diagram of the vertical phase separation structure of a block copolymer layer in an example where PS-b-PMMA is used as the block copolymer. The lamellar shape has a structure enclosed by dotted rectangles, and in this example, the PS portion and PMMA portion form layers stacked in parallel.

[0056] It is preferable that the above-mentioned block copolymer layer, preferably the PS-b-PMMA layer, further contains a carbonation layer of the surface energy of the block copolymer layer, preferably the PS-b-PMMA layer.

[0057] The neutralization of surface energy described above refers to bringing the surface energy of the entire block copolymer, which has a hydrophilic portion (e.g., PMMA) and a hydrophobic portion (e.g., PS), closer to or equal to the surface energy of the substrate surface in contact with the block copolymer, in order to achieve vertical phase separation of the block copolymer. When the surface energies of both are close or the same, a vertical phase separation structure is formed. Therefore, in order to achieve vertical phase separation of the block copolymer layer, preferably the PS-b-PMMA layer, it is common to form a surface energy neutralization layer on the substrate surface (i.e., below the block copolymer layer, preferably the PS-b-PMMA layer), however, this is not the case if the substrate surface already has the same or close surface energy as the entire block copolymer. This theory is described, for example, in Macromolecules 2006, 39, 2449-2451.

[0058] The neutralized layer described above may contain a polymer having a unit structure derived from an aromatic compound.

[0059] The above aromatic compound preferably contains an aryl group having 6 to 40 carbon atoms.

[0060] Examples of the above aryl groups having 6 to 40 carbon atoms include phenyl group, o-methylphenyl group, m-methylphenyl group, p-methylphenyl group, o-chlorophenyl group, m-chlorophenyl group, p-chlorophenyl group, o-fluorophenyl group, p-fluorophenyl group, o-methoxyphenyl group, p-methoxyphenyl group, p-nitrophenyl group, p-cyanophenyl group, α-naphthyl group, β-naphthyl group, o-biphenylyl group, m-biphenylyl group, p-biphenylyl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group, and 9-phenanthryl group. Among these, it is preferable to include a phenyl group, an α-naphthyl group (=1-naphthyl group), or a β-naphthyl group (=2-naphthyl group).

[0061] It is preferable that the polymer contains 40 mol% or more, 45 mol% or more, 50 mol% or more, 60 mol% or more, 70 mol% or more, or 80 mol% or more of the above-mentioned α-naphthyl group (=1-naphthyl group) or β-naphthyl group (=2-naphthyl group) relative to the total polymer. The upper limit is, for example, 95 mol% or 90 mol%.

[0062] The above polymer may be, for example, a polymer derived from 1-vinylnaphthalene, 2-vinylnaphthalene, or benzyl methacrylate. Preferably, it may be a polymer derived from 2-vinylnaphthalene or benzyl methacrylate.

[0063] The polymer preferably contains 50 mol% or more of the unit structure derived from the aromatic compound relative to the entire polymer. It is even more preferable that the polymer contains, relative to the entire polymer, the unit structure derived from the aromatic compound in amounts such as 50 mol% to 99 mol%, 55 mol% to 99 mol%, 60 mol% to 99 mol%, 65 mol% to 99 mol%, 70 mol% to 99 mol%, 75 mol% to 99 mol%, 80 mol% to 99 mol%, 81 mol% to 99 mol%, 82 mol% to 98 mol%, 83 mol% to 97 mol%, 84 mol% to 96 mol%, or 85 mol% to 95 mol%.

[0064] The above-mentioned neutralization layer may be a neutralization layer derived from a self-assembled film underlayer forming composition as described in Specification WO2014 / 097993. The above-mentioned neutralized layer may contain a polymer having a unit structure derived from a polycyclic aromatic vinyl compound. The polymer may contain a polymer having 0.2 mol% or more of the unit structure of a polycyclic aromatic vinyl compound per total unit structure of the polymer.

[0065] The polymer may be a polymer having 20 mol% or more of the unit structure of an aromatic vinyl compound per total unit structure of the polymer, and 1 mol% or more of the unit structure of a polycyclic aromatic vinyl compound per total unit structure of the aromatic vinyl compound.

[0066] The aromatic vinyl compound comprises vinylnaphthalene, acenaphthylene, or vinylcarbazole, each of which may be substituted, and the polycyclic aromatic vinyl compound may be vinylnaphthalene, acenaphthylene, or vinylcarbazole.

[0067] The aromatic vinyl compound comprises optionally substituted styrene and optionally substituted vinylnaphthalene, acenaphthylene, or vinylcarbazole, and the polycyclic aromatic vinyl compound may be vinylnaphthalene, acenaphthylene, or vinylcarbazole.

[0068] The aromatic vinyl compound may be substituted styrene and, respectively, substituted vinylnaphthalene, acenaphthylene, or vinylcarbazole, and the polycyclic aromatic vinyl compound may be substituted vinylnaphthalene, acenaphthylene, or vinylcarbazole.

[0069] The aromatic vinyl compound may consist solely of polycyclic aromatic vinyl compounds, and the aromatic vinyl compounds may be vinylnaphthalene, acenaphthylene, or vinylcarbazole, each of which may be substituted.

[0070] The polymer may have 60 to 95 mol% of aromatic vinyl compound units per total unit structure of the polymer.

[0071] The polymer further has a unit structure having a crosslinking group, and the crosslinking group may be a hydroxyl group, an epoxy group, a protected hydroxyl group, or a protected carboxyl group.

[0072] The above-mentioned neutralization layer may be formed from a neutralization layer-forming composition. The neutralization layer-forming composition may include a polymer having a unit structure derived from the above-mentioned aromatic compound and / or a polymer having a unit structure derived from the above-mentioned polycyclic aromatic vinyl compound, and examples of the embodiments of these polymers are the same as those described for the neutralization layer. In this specification, the terms "underlayer film" and "neutralization layer" may be used synonymously, and the terms "underlayer film-forming composition" may be used synonymously for "neutralization layer-forming composition".

[0073] The neutralization layer-forming composition of this invention may contain a crosslinking agent, an acid, or an acid generator.

[0074] <Crosslinking agent> Examples of crosslinking agents used in the neutralization layer-forming composition of this application include melamine compounds, substituted urea compounds, or polymer compounds thereof. Preferably, the crosslinking agent has at least two crosslinking substituents, and specifically includes compounds such as methoxymethylated glycoluryl, butoxymethylated glycoluryl, methoxymethylated melamine, butoxymethylated melamine, methoxymethylated benzoguanamine, butoxymethylated benzoguanamine, methoxymethylated urea, butoxymethylated urea, methoxymethylated thiourea, or methoxymethylated thiourea. Condensed products of these compounds can also be used.

[0075] Furthermore, the crosslinking agent of this application may be a nitrogen-containing compound having 2 to 6 substituents represented by the following formula (1d) that bond to a nitrogen atom in one molecule, as described in WO2017 / 187969. [ka] (In the formula, R1 represents a methyl group or an ethyl group.)

[0076] A nitrogen-containing compound having 2 to 6 substituents represented by formula (1d) in one molecule may be a glycoluryl derivative represented by the following formula (1E). [ka] (In the formula, each of the four R1s independently represents a methyl group or an ethyl group, and R2 and R3 independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group.)

[0077] Examples of glycoluryl derivatives represented by formula (1E) include the compounds represented by the following formulas (1E-1) to (1E-6). [ka]

[0078] A nitrogen-containing compound having 2 to 6 substituents represented by formula (1d) in one molecule can be obtained by reacting a nitrogen-containing compound having 2 to 6 substituents represented by the following formula (2d) that bond to a nitrogen atom in one molecule with at least one compound represented by the following formula (3d). [ka] (In the formula, R1 represents a methyl group or an ethyl group, and R4 represents an alkyl group having 1 to 4 carbon atoms.)

[0079] The glycoluryl derivative represented by formula (1E) is obtained by reacting a glycoluryl derivative represented by the following formula (2E) with at least one compound represented by formula (3d).

[0080] A nitrogen-containing compound having 2 to 6 substituents represented by formula (2d) in one molecule is, for example, a glycoluryl derivative represented by the following formula (2E). [ka] (In the formula, R2 and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a phenyl group, and R4 each independently represents an alkyl group having 1 to 4 carbon atoms.)

[0081] Examples of glycoluryl derivatives represented by formula (2E) include the compounds represented by formulas (2E-1) to (2E-4) below. Furthermore, examples of compounds represented by formula (3d) include the compounds represented by formulas (3d-1) and (3d-2) below. [ka] [ka]

[0082] With regard to nitrogen-containing compounds having 2 to 6 substituents represented by the following formula (1d) bonded to the above nitrogen atom in one molecule, the content described in Publication WO2017 / 187969 shall be as described.

[0083] The amount of crosslinking agent added to the neutralization layer-forming composition of the present invention is 0.001 to 80% by mass, preferably 0.01 to 50% by mass, and more preferably 0.05 to 40% by mass, relative to the total solid content. These crosslinking agents may undergo crosslinking reactions by self-condensation, but if crosslinkable substituents are present in the polymer of the present invention, they can undergo crosslinking reactions with those crosslinkable substituents.

[0084] <Acid or acid generator> The neutralization layer-forming composition of the present invention may contain an acid and / or an acid generator as a catalyst to promote the crosslinking reaction. Examples of acids include acidic compounds such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonic acid (=pyridinium-p-toluenesulfonate), salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoic acid, and naphthalenecarboxylic acid. Examples of acid generators include thermoacid generators such as 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, and other organic alkyl sulfonates. The amount of these compounds is 0.0001 to 20% by mass, preferably 0.0005 to 10% by mass, and preferably 0.01 to 3% by mass, based on the total solid content of the neutralization layer-forming composition of the present invention.

[0085] In addition to the thermal acid generator, photoacid generators can also be cited as the acid generating agent.

[0086] Examples of photoacid generators included in the neutralization layer-forming composition of the present invention include onium salt compounds, sulfonimide compounds, and disulfonyl diazomethane compounds.

[0087] Examples of iodonium salt compounds include iodonium salt compounds such as diphenyliodonium hexafluorophosphonate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoron-butanesulfonate, diphenyliodonium perfluoron-octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate, and sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoron-butanesulfonate, triphenylsulfonium camphorsulfonate and triphenylsulfonium trifluoromethanesulfonate.

[0088] Examples of sulfonimide compounds include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoron-butanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0089] Examples of disulfonyl diazomethane compounds include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

[0090] Only one type of photoacid generator may be used, or two or more types may be used in combination.

[0091] When a photoacid generator is used, the ratio is 0.01 to 5 parts by mass, or 0.1 to 3 parts by mass, or 0.5 to 1 part by mass, per 100 parts by mass of the solid content of the neutralization layer-forming composition of the present invention.

[0092] Further details regarding the neutralization layer-forming composition for forming the neutralization layer, which includes a polymer having a unit structure derived from the above-mentioned polycyclic aromatic vinyl compound, are as described in the WO2014 / 097993 specification, except for those described herein.

[0093] Other neutralizing layers include underlayer film-forming compositions used to phase-separate layers containing block copolymers formed on a substrate, as described in WO2018 / 135455, wherein the composition is a copolymer represented as follows: (A) Unit structure derived from a styrene compound containing a tert-butyl group, (B) A unit structure derived from an aromatic vinyl compound that does not contain a hydroxyl group, other than the unit structure in (A) above. (C) A unit structure derived from a compound containing a (meth)acryloyl group but not a hydroxyl group, (D) Includes a unit structure derived from a crosslinking group-containing compound, The underlying film may be formed by an underlying film-forming composition in which the copolymerization ratio to the entire copolymer is (A) 25-90 mol%, (B) 0-65 mol%, (C) 0-65 mol%, and (D) 10-20 mol%, and of (A)+(B)+(C), the unit structure containing aromatics is 81-90 mol%.

[0094] The unit structure (A) derived from the styrene compound containing the tert-butyl group described above may be represented by formula (1). [ka] (In formula (1), R 1 From R 3 One or two of these are tert-butyl groups.

[0095] The unit structure (D) derived from the above-mentioned crosslinking group-containing compound may be represented by formula (2-1), (2-2), (3-1), or (3-2). [ka] [ka] (In formulas (2-1) and (2-2), each of the n X's independently represents a hydroxyl group, a halogen atom, an alkyl group, an alkoxy group, a cyano group, an amide group, an alkoxycarbonyl group, or a thioalkyl group, and n represents an integer from 1 to 7.) [ka] [ka] (In equations (3-1) and (3-2), R 4 represents a hydrogen atom or a methyl group, R 5 represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may have a hydroxy group and may be substituted with a halogen atom, or a hydroxyphenyl group.)

[0096] A unit structure derived from an aromatic vinyl compound not containing the above hydroxy group, wherein the unit structure (B) other than the above (A) may be represented by the formula (4-1) or (4-2). [Chemical formula] [Chemical formula] (In the formulas (4-1) and (4-2), n Ys each independently represent a halogen atom, an alkyl group, an alkoxy group, a cyano group, an amide group, an alkoxycarbonyl group, or a thioalkyl group, and n represents an integer of 0 to 7.)

[0097] A unit structure (C) derived from a compound containing the above (meth)acryloyl group and not containing a hydroxy group may be represented by the formula (5-1) or (5-2). [Chemical formula] [Chemical formula] (In the formulas (5-1) and (5-2), R 9 represents a hydrogen atom or a methyl group, and R 10 each independently represents a hydrogen atom, an alkoxy group having 1 to 5 carbon atoms, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, a benzyl group, or an anthrylmethyl group.)

[0098] The above-mentioned unit structure is derived from an aromatic vinyl compound that does not contain a hydroxyl group, and the unit structure (B) other than (A) may be a unit structure derived from vinylnaphthalene.

[0099] Further details regarding the underlying film-forming composition of the present invention, other than those described herein, are as described in Specification WO2018 / 135455.

[0100] Other neutralization layers may be formed from a primer used to separate phases of a layer containing a block copolymer formed on a substrate by bonding multiple types of polymers, as described in Japanese Patent Application Publication No. 2012-062365, which contains a resin component, and is characterized in that 20 mol% to 80 mol% of the total constituent units of the resin component are constituent units derived from aromatic ring-containing monomers.

[0101] The resin component may contain structural units derived from non-aromatic ring-containing monomers.

[0102] The non-aromatic ring-containing monomer may be a vinyl compound or (meth)acrylic acid compound containing at least one atom selected from the group consisting of N, O, Si, P, and S.

[0103] The aromatic ring-containing monomer may be selected from the group consisting of aromatic compounds having 6 to 18 carbon atoms and having a vinyl group, aromatic compounds having 6 to 18 carbon atoms and having a (meth)acryloyl group, and phenols that are components of novolac resins. Furthermore, the polymerizable monomer may be present, or the resin component may contain a polymerizable group.

[0104] The term "(meth)acrylic acid" above refers to either or both of the following: acrylic acid with a hydrogen atom bonded at the α-position, and methacrylic acid with a methyl group bonded at the α-position. The same applies to "(meth)acrylic acid ester," "(meth)acrylate," and "(meth)acryloyl."

[0105] Aromatic compounds having 6 to 18 carbon atoms and containing a vinyl group include groups in which a hydrogen atom of the aromatic ring is substituted with a vinyl group, such as a phenyl group, biphenyl group, fluorenyl group, naphthyl group, anthryl group, and phenanthryl group, as well as monomers having heteroaryl groups in which some of the carbon atoms constituting the ring of these groups are substituted with heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. These may also have substituents other than the vinyl group.

[0106] Examples include α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-t-butylstyrene, 4-n-octylstyrene, 2,4,6-trimethylstyrene, 4-methoxystyrene, 4-t-butoxystyrene, 4-hydroxystyrene, 4-nitrostyrene, 3-nitrostyrene, 4-chlorostyrene, 4-fluorostyrene, 4-acetoxyvinylstyrene, vinylcyclohexane, 4-vinylbenzyl chloride, 1-vinylnaphthalene, 4-vinylbiphenyl, 1-vinyl-2-pyrrolidone, 9-vinylanthracene, vinylpyridine, and the like.

[0107] Aromatic compounds having 6 to 18 carbon atoms and containing a (meth)acryloyl group include groups in which a hydrogen atom of the aromatic ring is substituted with a (meth)acryloyl group, such as a phenyl group, biphenyl group, fluorenyl group, naphthyl group, anthryl group, and phenanthryl group, as well as monomers having heteroaryl groups in which some of the carbon atoms constituting the ring of these groups are substituted with heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. These may also have substituents other than the (meth)acryloyl group.

[0108] Examples include benzyl methacrylate, 1-(meth)acrylate-naphthalene, 4-methoxynaphthalene (meth)acrylate, 9-anthracene (meth)acrylate, and phenoxyethyl (meth)acrylate. For further details on the above primers, anything not described herein shall be in accordance with the contents of Japanese Patent Application Publication No. 2012-062365.

[0109] The weight-average molecular weight of the polymer contained in the neutralization layer of this invention is, for example, 1,000 to 50,000 or 2,000 to 30,000.

[0110] The neutralization layer-forming composition of the present invention preferably contains a polymer used for the neutralization layer and a solvent. Specific examples of preferred solvents are the same as those contained in the block copolymer layer-forming composition (preferably the PS-b-PMMA layer-forming composition) described above.

[0111] In one embodiment of the present invention, the neutralization layer may include a polymer having a unit structure in which the aliphatic polycyclic structure of an aliphatic polycyclic compound is included in the main chain.

[0112] The above polymer may be a polymer having a unit structure that includes the aliphatic polycyclic structure of an aliphatic polycyclic compound and the aromatic ring structure of an aromatic ring-containing compound in its main chain.

[0113] The above polymer may be a polymer having a unit structure in which the main chain includes the aliphatic polycyclic structure of an aliphatic polycyclic compound and a polymerization chain derived from the vinyl group of a vinyl group-containing compound.

[0114] The above polymer is of the following formula (1a): [ka] The unit structure may be represented by (formula (1a)), where X is a divalent group whose polymerization chain is a vinyl structure derived from a single bond or vinyl group-containing compound, or a divalent group whose polymerization chain is an aromatic ring-containing structure derived from an aromatic ring-containing compound, and Y is a divalent group whose polymerization chain is an aliphatic polycyclic structure derived from an aliphatic polycyclic compound. The aliphatic polycyclic compound may be a diene compound with 2 to 6 rings. The aliphatic polycyclic compound may be dicyclopentadiene or norbornadiene. The vinyl group-containing compound may be an alkene, acrylate, or methacrylate. The aromatic ring-containing compound may be a monocyclic or heterocyclic compound. The benzene may be substituted with a monocyclic compound, or the naphthalene may be substituted. The heterocyclic compound may be a substituted carbazole or a substituted phenothiazine.

[0115] The polymer represented by formula (1a) above has, for example, a unit structure represented by the following formulas (3-1a) to (3-12a). [ka]

[0116] Details regarding the neutralization layer containing a polymer having a unit structure that includes the aliphatic polycyclic structure of the above aliphatic polycyclic compound in its main chain are as described in WO2015 / 041208.

[0117] The neutralization layer of this invention may contain polysiloxane.

[0118] The polysiloxane may be a hydrolysis condensate of a silane containing a phenyl group.

[0119] The polysiloxane is given by formula (1b): [ka] (In the formula, R 1 R represents an alkoxy group, an acyloxy group, or a halogen atom. 2 The hydrolysis condensate of silane may contain 10 to 100 mol% of a silane represented by (where is an organic group containing a benzene ring which may have substituents and is bonded to a silicon atom by a Si-C bond) in total silane, but this proportion is preferably 60 to 100 mol%.

[0120] The polysiloxane may be a hydrolysis condensate of silanes containing the silane represented by formula (1b), the silane represented by formula (2b), and the silane represented by formula (3b) in a molar ratio of 10-100:0-90:0-50 in the total silane. [ka] (In the formula, R 3 and R 5 R represents an alkoxy group, an acyloxy group, or a halogen atom. 4 (This represents an organic group containing hydrocarbons, which may have substituents, and which is bonded to a silicon atom by a Si-C bond.)

[0121] The polysiloxane may be a hydrolysis condensate of silanes containing a silane represented by formula (1b) and a silane represented by formula (2b) in a ratio of 10 to 100:0 to 90 mole percent in the total silane. The polysiloxane may be a hydrolysis condensate of silanes containing a silane represented by formula (1b) and a silane represented by formula (3b) in a ratio of 10 to 100:0 to 90 mole percent in the total silane. In the above equation (1b), R 2 R may be a phenyl group. In the above formula (2b), 4 R may be a methyl group or a vinyl group. In the above formula (3b), 5 It may be an ethyl group.

[0122] Details regarding the neutralization layer containing the polysiloxane described above are in accordance with the information provided in WO2013 / 146600.

[0123] A block copolymer layer, preferably a PS-b-PMMA layer, may be formed as the neutralization layer by vertical phase separation using a brushing agent.

[0124] For example, in the polymer brush method described in Japanese Patent Application Publication No. 2016-160431, a lower layer (neutralized layer) of a block copolymer may be formed by placing a composition on a substrate, comprising: a block copolymer comprising a first polymer and a second polymer, wherein the first polymer and the second polymer of the block copolymer are different from each other, and the block copolymer forms a layer separation structure; an addition polymer comprising a bottle brush polymer, wherein the bottle brush polymer comprises a polymer having a lower or higher surface energy than the block copolymer; and a solvent.

[0125] Alternatively, the method using a brush agent as described in Science 07 Mar 1997: Vol. 275, Issue 5305, pp. 1458-1460 may also be used.

[0126] Preferred brushing agents of the present invention include polymers having reactive substituents at their ends. That is, in one embodiment of the present invention, the neutralization layer includes a polymer having reactive substituents at its ends.

[0127] Reactive substituents are substituents that can bond to silicon, SiN, SiON, silicon hard masks, etc., and contribute to the block copolymer arrangement as so-called brushing agents. Examples of such reactive substituents include hydroxyl groups, 1,2-ethanediol groups, carboxyl groups, amino groups, thiol groups, phosphate groups, and methine groups.

[0128] Specific examples of polymers having reactive substituents at their ends include, for example, polystyrene / poly(methyl methacrylate) random copolymers having hydroxyl groups at their ends. It is preferable that the molar ratio of polystyrene to the entire random copolymer is 60 mol% or more, 65 mol% or more, 70 mol% or more, 80 mol% or more, 81 mol% or more, 85 mol or more, or 90 mol or more. The weight-average molecular weight of the polymer forming the brush agent is, for example, in the range of 5,000 to 50,000. The polydispersity (Mw / Mn) is preferably 1.10 to 2.00.

[0129] The silicon hard mask may be a known silicon hard mask (also called a silicon-containing resist underlayer), for example, silicon hard masks (silicon-containing resist underlayers) described in WO2019 / 181873, WO2019 / 124514, WO2019 / 082934, WO2019 / 009413, WO2018 / 181989, WO2018 / 079599, WO2017 / 145809, WO2017 / 145808, WO2016 / 031563, etc.

[0130] <Circuit board> A vertically phase-separated block copolymer layer, preferably a PS-b-PMMA layer, is preferably formed on the substrate. The above-mentioned substrate may be a so-called semiconductor substrate, and examples include silicon wafers, germanium wafers, and compound semiconductor wafers such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride.

[0131] When using a semiconductor substrate with an inorganic film formed on its surface, the inorganic film is formed by, for example, ALD (atomic layer deposition), CVD (chemical vapor deposition), reactive sputtering, ion plating, vacuum deposition, or spin coating (spin-on-glass: SOG). Examples of the inorganic film include polysilicon films, silicon oxide films, silicon nitride films, BPSG (Boro-Phospho-Silicate Glass) films, titanium nitride films, titanium oxide nitride films, tungsten films, gallium nitride films, and gallium arsenide films.

[0132] A neutralization layer-forming composition is applied to such a semiconductor substrate using an appropriate coating method such as a spinner or coater. Subsequently, a neutralization layer is formed by baking using a heating means such as a hot plate. The baking conditions are appropriately selected from a baking temperature of 100°C to 400°C and a baking time of 0.3 minutes to 60 minutes. Preferably, the baking temperature is 120°C to 350°C and the baking time is 0.5 minutes to 30 minutes, and more preferably, the baking temperature is 150°C to 300°C and the baking time is 0.8 minutes to 10 minutes.

[0133] The thickness of the neutralized layer formed can be, for example, 0.001 μm (1 nm) to 10 μm, 0.002 μm (2 nm) to 1 μm, 0.005 μm (5 nm) to 0.5 μm (500 nm), 0.001 μm (1 nm) to 0.05 μm (50 nm), 0.002 μm (2 nm) to 0.05 μm (50 nm), 0.003 μm (3 nm) to The nanoscale ranges are 0.05 μm (50 nm), 0.004 μm (4 nm) to 0.05 μm (50 nm), 0.005 μm (5 nm) to 0.05 μm (50 nm), 0.003 μm (3 nm) to 0.03 μm (30 nm), 0.003 μm (3 nm) to 0.02 μm (20 nm), and 0.005 μm (5 nm) to 0.02 μm (20 nm).

[0134] Phase separation of block copolymer layers can be achieved in the presence of an upper film by treatments that result in the rearrangement of the block copolymer material, such as sonication, solvent treatment, or thermal annealing. In many applications, it is desirable to achieve phase separation of block copolymer layers simply by heating or so-called thermal annealing. Thermal annealing can be performed in air or in an inert gas under atmospheric pressure, reduced pressure, or pressurized conditions.

[0135] <Method for producing vertically phase-separated block copolymer layers> The present invention relates to a method for producing a vertically phase-separated block copolymer layer, preferably a PS-b-PMMA layer, which includes the steps of forming a block copolymer layer, preferably a PS-b-PMMA layer, on a substrate, and then heating the substrate at a pressure below atmospheric pressure. The details of the above conditions are the same as those described above for the vertically phase-separated block copolymer layer, preferably a PS-b-PMMA layer.

[0136] Phase separation of a block copolymer layer, preferably a PS-b-PMMA layer, forms block copolymer domains oriented substantially perpendicular to the substrate or neutralized layer surface. The morphology of the domains can be, for example, lamellar, spherical, or cylindrical. The domain spacing can be, for example, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. According to the method of the present invention, it is possible to form a vertically phase-separated block copolymer layer, preferably a PS-b-PMMA layer, having a desired size, shape, orientation, and periodicity.

[0137] <Manufacturing method for semiconductor devices> The block copolymer layer, preferably a PS-b-PMMA layer, that has been vertically phase-separated by the above method can be further subjected to an etching process. Typically, a portion of the phase-separated block copolymer layer, preferably a PS-b-PMMA layer, is removed before etching. Etching can be carried out by known means. This method can be used for the manufacture of semiconductor substrates.

[0138] In other words, the method for manufacturing a semiconductor device according to the present invention includes (1) the step of forming a neutralized layer on a substrate using a neutralized layer forming composition according to the present invention; (2) the step of forming a block copolymer layer, preferably a PS-b-PMMA layer, on the neutralized layer; (3) the step of phase-separating the block copolymer layer, preferably a PS-b-PMMA layer, formed on the neutralized layer; (4) the step of etching the phase-separated block copolymer layer, preferably a PS-b-PMMA layer; and (5) the step of etching the substrate.

[0139] For etching, gases such as tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride and chlorine trifluoride, chlorine, trichloroborane and dichloroborane can be used.

[0140] By utilizing the pattern of a vertically phase-separated block copolymer layer, preferably a PS-b-PMMA layer, according to the present invention, it is possible to impart a desired shape to a substrate to be processed by etching and to fabricate a suitable semiconductor device. [Examples]

[0141] The present invention will be described more specifically below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0142] [Example 1] (Preparation of Block Copolymer 1) 0.5 g of polystyrene / poly(methyl methacrylate) copolymer (manufactured by POLYMER SOURCE INC., PS(Mw:22,000, Mn:21,000)-b-PMMA(Mw:22,900, Mn:21,000), polydispersity = 1.07), a block copolymer, was dissolved in 24.5 g of propylene glycol monomethyl ether acetate to prepare a 2% by mass solution. This solution was then filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a solution of self-assembling film-forming composition 1 containing block copolymer 1.

[0143] The weight-average molecular weight (Mw) of the polymers shown in the synthesis examples below was measured using gel permeation chromatography (GPC). A GPC instrument manufactured by Tosoh Corporation was used for the measurement, and the measurement conditions were as follows. Measuring device: HLC-8020GPC [product name] (manufactured by Tosoh Corporation) GPC columns: TSKgel G2000HXL (product name): 2 tubes, G3000HXL (product name): 1 tube, G4000HXL (product name): 1 tube (all manufactured by Tosoh Corporation) Column temperature: 40℃ Solvent: Tetrahydrofuran (THF) Flow rate: 1.0ml / min Standard sample: Polystyrene (manufactured by Tosoh Corporation)

[0144] (Preparation of Block Copolymer 2) A solution of block copolymer 2 was prepared in the same manner as the preparation of block copolymer 1, except that polystyrene / poly(methyl methacrylate) copolymer (manufactured by POLYMER SOURCE INC., PS(Mw:22,000, Mn:21,000)-b-PMMA(Mw:22,900, Mn:21,000), polydispersity=1.09) was used instead of polystyrene / poly(methyl methacrylate) copolymer (manufactured by POLYMER SOURCE INC., PS(Mw:35,500, Mn:33,000)-b-PMMA(Mw:36,400, Mn:37).

[0145] [Synthesis Example 1] Synthesis of Polymer 1 6.23 g of 2-vinylnaphthalene (85% molar ratio to the total polymer 1), 0.93 g of hydroxyethyl methacrylate (15% molar ratio to the total polymer 1), and 0.36 g of 2,2'-azobisisobutyronitrile were dissolved in 22.50 g of propylene glycol monomethyl ether acetate. This solution was then heated and stirred at 85°C for approximately 24 hours. The reaction mixture was added dropwise to methanol, and the precipitate was collected by suction filtration. Polymer 1 was then recovered by drying under reduced pressure at 60°C. The weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 6,000.

[0146] [Synthesis Example 2] Synthesis of Polymer 2 4.77 g of 2-vinylnaphthalene (60% molar ratio of polymer 2), 1.34 g of hydroxyethyl methacrylate (20% molar ratio of polymer 2), 1.03 g of methyl methacrylate (20% molar ratio of polymer 2), and 0.36 g of 2,2'-azobisisobutyronitrile were dissolved in 22.50 g of propylene glycol monomethyl ether acetate. This solution was then heated and stirred at 85°C for approximately 24 hours. The reaction mixture was added dropwise to methanol, and the precipitate was collected by suction filtration. Polymer 2 was then recovered by drying under reduced pressure at 60°C. The weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 6,000.

[0147] [Synthesis Example 3] Synthesis of Polymer 3 2.57 g of 2-vinylnaphthalene (50% molar ratio of polymer 3), 2.06 g of benzyl methacrylate (35% molar ratio of polymer 3), 0.72 g of hydroxyethyl methacrylate (15% molar ratio of polymer 3), and 0.33 g of 2,2'-azobisisobutyronitrile were dissolved in 22.50 g of propylene glycol monomethyl ether acetate. This solution was then heated and stirred at 85°C for approximately 24 hours. The reaction mixture was added dropwise to methanol, and the precipitate was collected by suction filtration. Polymer 3 was then recovered by drying under reduced pressure at 60°C. The weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 5900.

[0148] [Synthesis Example 4] Synthesis of Polymer 4 6.13 g of 2-vinylnaphthalene (85% molar ratio of the total polymer 4), 1.01 g of hydroxypropyl methacrylate (15% molar ratio of the total polymer 4), and 0.36 g of 2,2'-azobisisobutyronitrile were dissolved in 22.50 g of propylene glycol monomethyl ether acetate. This solution was then heated and stirred at 85°C for approximately 24 hours. The reaction mixture was added dropwise to methanol, and the precipitate was collected by suction filtration. Polymer 4 was then recovered by drying under reduced pressure at 60°C. The weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 6,200.

[0149] [Synthesis Example 5] Synthesis of Polymer 5 11.00 g of vinylcarbazole (80% molar ratio to the total polymer 5), 1.85 g of hydroxyethyl methacrylate (20% molar ratio to the total polymer 5), and 0.39 g of 2,2'-azobisisobutyronitrile were dissolved in 30.89 g of propylene glycol monomethyl ether acetate. This solution was then heated and stirred at 85°C for approximately 19 hours. The weight-average molecular weight (Mw) of the resulting polymer 5, measured in polystyrene equivalent by GPC, was 6,950.

[0150] [Synthesis Example 6] Synthesis of Polymer 6 5.00 g of dicyclopentadiene-type epoxy resin (product name: EPICLON HP-7200H, manufactured by DIC Corporation), 3.58 g of 4-phenylbenzoic acid, and 0.17 g of ethyltriphenylphosphonium bromide were mixed with 34.98 g of propylene glycol monomethyl ether, and the mixture was heated under a nitrogen atmosphere under reflux for 16 hours. The weight-average molecular weight Mw of the resulting polymer 6, measured in polystyrene equivalent by GPC, was 1,800.

[0151] [Synthesis Example 7] Synthesis of Polymer 7 5.50 g of dicyclopentadiene-type epoxy resin (product name: EPICLON HP-7200H, manufactured by DIC Corporation), 3.54 g of 4-tert-butylbenzoic acid, and 0.18 g of ethyltriphenylphosphonium bromide were added to 36.89 g of propylene glycol monomethyl ether, and the mixture was heated under a nitrogen atmosphere under reflux for 15 hours. The weight-average molecular weight Mw of the resulting polymer 7, measured in polystyrene equivalent by GPC, was 2,000.

[0152] [Synthesis Example 8] Synthesis of Polymer 8 13.88 g of phenyltrimethoxysilane (containing 70 mol% of the total silane), 5.35 g of tetraethoxysilane (containing 30 mol% of the total silane), and 28.84 g of acetone were placed in a 100 ml flask. While stirring the mixture with a magnetic stirrer, 5.41 g of 0.01 mol / l hydrochloric acid was added dropwise to the mixture. After the addition, the flask was transferred to an oil bath adjusted to 85°C and reacted under heated reflux for 4 hours. The reaction solution was then cooled to room temperature, and 75 g of propylene glycol monomethyl ether acetate was added to the reaction solution. The reaction by-products methanol, ethanol, water, and hydrochloric acid were removed by distillation under reduced pressure, and the solution was concentrated to obtain a polymer solution. Propylene glycol monoethyl ether was added to this solution, and the solvent ratio was adjusted to propylene glycol monomethyl ether acetate / propylene glycol monoethyl ether = 20 / 80. The weight-average molecular weight Mw of the obtained polymer 8, measured in polystyrene equivalent by GPC, was 1,200.

[0153] (Preparation of Underlayer Film Forming Composition 1) 0.39 g of the polymer obtained in Synthesis Example 1 was mixed with 0.10 g of tetramethoxymethyl glycoluryl and 0.05 g of pyridinium-p-toluenesulfonate. 69.65 g of propylene glycol monomethyl ether acetate and 29.37 g of propylene glycol monomethyl ether were added and dissolved. The mixture was then filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a solution of the self-assembling film-forming composition 1.

[0154] (Preparation of lower layer film-forming compositions 2-5) The underlying film-forming compositions 2 to 5 were prepared in the same manner as the preparation of underlying film-forming composition 1, except that the polymers obtained in Synthesis Examples 2 to 5 were used instead of the polymer obtained in Synthesis Example 1.

[0155] (Preparation of the lower layer film-forming composition 6) 0.26 g of the polymer obtained in Synthesis Example 6 was mixed with 0.07 g of tetramethoxymethyl glycoluryl and 0.007 g of pyridinium-p-toluenesulfonate. 8.90 g of propylene glycol monomethyl ether acetate and 20.76 g of propylene glycol monomethyl ether were added and dissolved. The mixture was then filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a solution of the self-assembling film-forming composition 6.

[0156] (Preparation of the lower layer film-forming composition 7) The underlying film-forming composition 7 was prepared in the same manner as the preparation of the underlying film-forming composition 6, except that the polymer obtained in synthesis example 7 was used instead of the polymer obtained in synthesis example 6.

[0157] (Preparation of the lower layer film-forming composition 8) To 1.33 g of the polymer obtained in Synthesis Example 8, 0.006 g of maleic acid and 0.0012 g of benzyltriethylammonium chloride were mixed. Then, 0.68 g of propylene glycol monomethyl ether acetate, 0.79 g of propylene glycol monomethyl ether, 9.10 g of 1-ethoxy-2-propanol, and 1.30 g of ultrapure water were added and dissolved. The mixture was then filtered using a fluororesin microfilter with a pore size of 0.1 μm to prepare a solution of the self-assembling film underlayer forming composition 8.

[0158] (Preparation of the underlayer film-forming composition 9 using brush material) 0.3 g of polystyrene / poly(methyl methacrylate) random copolymer (manufactured by POLYMER SOURCE INC., with hydroxyl groups at the ends, 72% molar ratio of polystyrene, 28% molar ratio of poly(methyl methacrylate), Mw=8,120, polydispersity=1.16) was dissolved in 29.7 g of propylene glycol monomethyl ether acetate to prepare a 1% by mass solution. This solution was then filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a solution of the lower film-forming composition 9 using a brush material.

[0159] [Example 2] (Evaluation of self-assembly of block copolymers) The self-assembled film base layer formation composition 1 obtained above was applied to a silicon wafer and heated on a hot plate at 240°C for 1 minute to obtain a base layer (layer A) with a thickness of 5-10 nm. A self-assembled film formation composition containing block copolymer 1 was applied on top of this using a spin coater and heated on a hot plate at 100°C for 1 minute to form a self-assembled film (layer B) with a thickness of 40 nm. The wafer coated with this self-assembled film was heated at 290°C for 15 minutes using a Lam Research etching system (Lam 2300 MWS) at a pressure of 1,000 mTorr and in an O2 / N2 mixed gas atmosphere (mixing ratio: O2:N2=2:8 (flow rate ratio)) to induce a microphase separation structure of the self-assembled film.

[0160] (Observation of microphase separation structure) A silicon wafer in which a microphase separation structure was induced was etched using a Lam Research etching system (Lam 2300 Versys Kiyo45) with O2 / N2 gas as the etching gas for 3 seconds, preferentially etching the poly(methyl methacrylate) region. Subsequently, the shape was observed using an electron microscope (S-4800, Hitachi High-Technologies).

[0161] [Examples 3-9] The microphase separation structure was observed in the same manner as in Example 2, except that underlayer film-forming compositions 2 to 8 were used instead of underlayer film-forming composition 1.

[0162] [Examples 10-11] The microphase separation structure was observed in the same manner as in Example 2, except that heating was performed in N2 or O2 gas instead of under an O2 / N2 mixed gas atmosphere.

[0163] [Example 12] The microphase separation structure was observed in the same manner as in Example 2, except that instead of heating at 290°C for 15 minutes at a pressure below atmospheric pressure and in an O2 / N2 mixed gas atmosphere (mixing ratio: O2:N2=2:8 (flow rate ratio)) using an etching apparatus manufactured by Lam Research, Inc. (Lam 2300 MWS), the sample was heated at 290°C for 15 minutes under conditions of 1,000 mTorr and in a nitrogen atmosphere using a vacuum heating apparatus manufactured by Ayumi Industries, Inc. (VJ-300-S).

[0164] [Examples 13-19] The microphase separation structure was observed in the same manner as in Example 12, except that underlayer film-forming compositions 2 to 8 were used instead of underlayer film-forming composition 1.

[0165] [Examples 20-23] The microphase separation structure was observed in the same manner as in Example 12, except that instead of heating at 290°C, the samples were heated at 240°C, 260°C, 270°C, or 300°C, respectively.

[0166] [Example 24] The microphase separation structure was observed in the same manner as in Example 12, except that instead of heating at 290°C for 15 minutes, it was heated at 320°C for 5 minutes.

[0167] [Examples 25-27] The microphase separation structure was observed in the same manner as in Example 12, except that heating was performed at 500 mTorr, 5,000 mTorr, and 10,000 mTorr instead of heating at a pressure of 1,000 mTorr.

[0168] [Example 28] The microphase separation structure was observed in the same manner as in Example 12, except that a solution of block copolymer 2 was used instead of a solution of block copolymer 1.

[0169] [Example 29] The microphase separation structure was observed in the same manner as in Example 12, except that instead of applying underlayer film-forming composition 1 to a silicon wafer and heating it on a hot plate at 240°C for 1 minute, underlayer film-forming composition 9 was applied to a silicon wafer, heated on a hot plate at 200°C for 2 minutes, and then immersed in propylene glycol monomethyl ether acetate to remove any polymer that was not adhering to the silicon wafer, and the resulting underlayer film was used.

[0170] [Comparative Example 1] The microphase separation structure was observed in the same manner as in Example 2, except that instead of heating at 290°C for 15 minutes at a pressure below atmospheric pressure and in an O2 / N2 mixed gas atmosphere using a Lam Research etching apparatus (Lam 2300 MWS), the sample was heated on a hot plate at atmospheric pressure (760,000 mTorr) and in an air atmosphere for 15 minutes.

[0171] (Confirmation of block copolymer arrangement) The arrangement properties of the block copolymers prepared in Examples 2-29 and Comparative Example 1 were confirmed. The results are shown in Table 1, and Figure 3 shows examples of vertical arrangement (vertically arranged lamellar structure) and poor arrangement based on electron microscope observations (magnification: 200K). In Table 1, "vertical arrangement" refers to "vertically arranged lamellar structure." [Table 1]

[0172] As shown in Table 1, the method of inducing microphase separation by heating at a pressure below atmospheric pressure according to the present invention makes it possible to induce vertical alignment of block copolymers, particularly PS-b-PMMA block copolymers, in a temperature range in which induced self-assembly can occur, preferably in a high-temperature range (290°C or higher). [Industrial applicability]

[0173] According to the invention, it is possible to induce a microphase separation structure of the block copolymer layer perpendicular to the substrate across the entire coated film without causing poor alignment of the microphase separation of the block copolymer, which is extremely useful in industry.

[0174] The disclosure of Japanese Patent Application No. 2020-138906 (filing date: August 19, 2020) is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A method for manufacturing a vertically phase-separated block copolymer layer for semiconductor device manufacturing, The process includes the steps of forming a block copolymer layer on a substrate, and then heating the substrate at a pressure below atmospheric pressure, wherein the heating is performed at a temperature of 290°C or higher. The aforementioned block copolymer is PS-b-PMMA, The aforementioned block copolymer layer further comprises a neutralization layer of the surface energy of the block copolymer, The neutralized layer comprises (a) a polymer having a unit structure derived from a polycyclic aromatic vinyl compound, (b) a polymer having a unit structure containing an aliphatic polycyclic structure of an aliphatic polycyclic compound in its main chain, (c) a polysiloxane, or (d) a polymer having a reactive substituent at its terminus. A method for manufacturing vertically phase-separated block copolymer layers for semiconductor device manufacturing.

2. The method for producing a vertically phase-separated block copolymer layer according to Claim 1, wherein the vertical phase separation includes a lamellar-shaped portion.

3. A method for manufacturing a semiconductor device, comprising the steps of: forming a vertically phase-separated block copolymer layer on a substrate using the method for manufacturing a vertically phase-separated block copolymer layer described in Claim 1 or 2; etching the vertically phase-separated block copolymer layer; and etching the substrate.

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