WO2020170934A1

WO2020170934A1 - Film-forming composition and method for producing semiconductor substrate

Info

Publication number: WO2020170934A1
Application number: PCT/JP2020/005574
Authority: WO
Inventors: 智昭瀬古; 達也 ▲葛▼西; 智也田路; 博允田中
Original assignee: Jsr株式会社
Priority date: 2019-02-22
Filing date: 2020-02-13
Publication date: 2020-08-27
Also published as: JPWO2020170934A1; KR20210132038A; JP7342939B2; TW202035530A

Abstract

The purpose of the present invention is to provide: a film-forming composition capable of forming a silicon-containing film excellent in terms of filling property, flatness, and resistance to etching with oxygen-containing gases; and a method for producing a semiconductor substrate. The film-forming composition of the present invention comprises a polysilane and a solvent, wherein the polysilane has two or more first structural units, which are represented by formula (1). In formula (1), R¹ is a hydrogen atom or a monovalent organic chain group having 1-20 carbon atoms. R² is a hydrogen atom, a hydroxy group, or a monovalent organic chain group having 1-20 carbon atoms. It is preferable that R² in formula (1) be -OR^A and R^A be a hydrogen atom or a monovalent organic chain group having 1-20 carbon atoms. It is preferable that R^A be a hydrogen atom or a monovalent hydrocarbon chain group having 1-20 carbon atoms.

Description

Film forming composition and method for manufacturing semiconductor substrate

The present invention relates to a film forming composition and a method for manufacturing a semiconductor substrate.

For pattern formation in the manufacture of a semiconductor substrate, patterning is performed, for example, by performing etching using a resist pattern obtained by exposing and developing a resist film laminated on the substrate via an organic lower layer film, a silicon-containing film, etc. as a mask. A semiconductor lithography process or the like for forming the formed substrate is used.

A method for forming a pattern on a substrate using a composition containing a polysilane compound as a composition for forming a silicon-containing film has been studied (see Japanese Patent Application Laid-Open No. 11-256106 and International Publication No. 2009/028511).

Japanese Patent Laid-Open No. 11-256106 International Publication No. 2009/028511

Recently, substrates on which patterns such as trenches and vias are formed are often used, and a film forming composition is required to be able to sufficiently embed these patterns and to have excellent flatness. Has been done. Further, the film-forming composition is also required to have excellent resistance to oxygen-based gas etching. However, the above-mentioned conventional film-forming composition cannot satisfy these requirements.

The present invention has been made based on the above circumstances, and an object thereof is a film-forming composition capable of forming a silicon-containing film excellent in embedding property, flatness, and oxygen-based gas etching resistance, and It is to provide a method for manufacturing a semiconductor substrate.

The invention made to solve the above problems contains polysilane (hereinafter, also referred to as “[A] polysilane”) and a solvent (hereinafter, also referred to as “[B] solvent”), and the above [A] polysilane. Is a film-forming composition having 2 or more first structural units represented by the following formula (1) (hereinafter, also referred to as “structural unit (I)”).

(In the formula (1), R ¹ is a hydrogen atom or a monovalent chain organic group having 1 to 20 carbon atoms. R ² is a hydrogen atom, a hydroxy group or a monovalent chain having 1 to 20 carbon atoms. It is a chain organic group.)

Another invention made to solve the above problems is a method for manufacturing a semiconductor substrate, which comprises a step of directly or indirectly coating the film forming composition on the substrate.

According to the film-forming composition and the method for producing a semiconductor substrate of the present invention, silicon-containing which is excellent in embedding property, flatness and oxygen-based gas etching resistance, and further excellent in organic solvent resistance, acid solution releasability and pattern formability. A film can be formed. Therefore, these can be suitably used for manufacturing semiconductor devices, which are expected to be further miniaturized in the future.

FIG. 1 is a schematic cross-sectional view for explaining the flatness evaluation method.

<Film forming composition>
The film forming composition contains [A] polysilane and a [B] solvent. The film forming composition contains a siloxane compound (hereinafter, also referred to as “[C] siloxane compound”) and/or an acid generator (hereinafter, also referred to as “[D] acid generator”) as suitable components. May be contained, and other optional components may be contained within a range not impairing the effects of the present invention.

Since the film forming composition contains [A] polysilane and [B] solvent, it has excellent embedding properties, flatness, and oxygen-based gas etching resistance, and further has organic solvent resistance, acid solution peeling property, and pattern formation. It is possible to form a silicon-containing film having excellent properties (hereinafter collectively referred to as “characteristics of silicon-containing film”). The reason why the film-forming composition has the above-mentioned effects to achieve the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, since [A] polysilane has two or more structural units (I) having a specific structure, it has organic solvent resistance, and the Si—Si structure is changed to a Si—O—Si structure by heating in the atmosphere. By doing so, it is considered that thermal contraction is suppressed, and the flatness is improved. Further, the [A] polysilane having the above-mentioned specific structure is considered to be a structure which is hardly decomposed by oxygen plasma, and the oxygen-based gas etching resistance is improved. Furthermore, the [A] polysilane having the above-mentioned specific structure is changed in the Si—Si structure to the Si—O—Si structure by heating in the air, and is excellent in the acid solution peeling property. Since the physical properties of [A] polysilane having the above-mentioned specific structure are changed by exposure to an electron beam or extreme ultraviolet rays, a pattern of a silicon-containing film can be formed by a development treatment.
Hereinafter, each component will be described.

<[A] polysilane>
“Polysilane” refers to a polymer having a Si—Si bond in the main chain. "Polymer" refers to a compound having two or more structural units. [A] Polysilane has two or more structural units (I). That is, [A] polysilane is a compound having the structural unit (I) as a repeating unit.

The lower limit of the number of structural units (I) in [A] polysilane is 2, 5, is preferable, 10 is more preferable, and 15 is particularly preferable. The upper limit of the number is, for example, 50, preferably 40, and more preferably 30.

The [A] polysilane may have a second structural unit represented by the formula (2) described later (hereinafter, also referred to as “structural unit (II)”) in addition to the structural unit (I). It may have a structural unit other than the unit (I) and the structural unit (II). [A] Polysilane may have one kind or two or more kinds of each structural unit.
Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit represented by the following formula (1).

In the above formula (1), R ¹ is a hydrogen atom or a monovalent chain organic group having 1 to 20 carbon atoms. R ² is a hydrogen atom, a hydroxy group or a monovalent chain organic group having 1 to 20 carbon atoms.

“Organic group” means a group containing at least one carbon atom. “Chain” means not containing a ring structure, and includes both linear and branched chains.

The monovalent chain organic group having 1 to 20 carbon atoms represented by R ¹ and R ² includes, for example, monovalent chain hydrocarbon group having 1 to 20 carbon atoms and carbon of the chain hydrocarbon group. -A monovalent group (α1) containing a divalent heteroatom-containing group between carbons, a part or all of the hydrogen atoms contained in the chain hydrocarbon group and the group (α1) is a monovalent heteroatom-containing group Examples thereof include a substituted monovalent group (β1), the chain hydrocarbon group, the group (α1) or a monovalent group (γ1) obtained by combining the group (β1) with a divalent hetero atom-containing group.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include chain chains such as alkanes such as methane, ethane, propane and butane, alkenes such as ethene, propene and butene, and alkynes such as ethyne, propyne and butyne. Examples thereof include groups excluding one hydrogen atom contained in hydrocarbon.

Examples of the hetero atom constituting the divalent or monovalent hetero atom-containing group include oxygen atom, nitrogen atom, sulfur atom, phosphorus atom, silicon atom, halogen atom and the like.

Examples of the divalent hetero atom-containing group include -O-, -CO-, -S-, -CS-, -NR'-, and groups in which two or more of these are combined. R'is a hydrogen atom or a monovalent chain hydrocarbon group. Among these, -O- or -S- is preferable, and -O- is more preferable.

Examples of the monovalent hetero atom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, amino group and sulfanyl group.

R ¹ is preferably a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or a carbon atom. The alkyl groups of the numbers 1 to 6 are more preferable, and the methyl group or the ethyl group is particularly preferable.

As R ² , —OR ^A is preferable. R ^A is a hydrogen atom or a monovalent chain organic group having 1 to 20 carbon atoms. Examples of the monovalent chain organic group having 1 to 20 carbon atoms represented by R ^A include the same groups as those exemplified as the monovalent chain organic group having 1 to 20 carbon atoms for R ^1. Etc. As R ^A , a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 20 carbon atoms is preferable, a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 6 carbon atoms is more preferable, and a hydrogen atom or carbon atom. The alkyl groups of the numbers 1 to 6 are more preferable, and the methyl group or the ethyl group is particularly preferable.

Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-9) (hereinafter, also referred to as “structural units (I-1) to (I-9)”) and the like. Is mentioned.

The structural unit (I) is preferably the structural unit (I-1), (I-2) or (I-6).

As the lower limit of the content ratio of the structural unit (I), 1 mol% is preferable, 10 mol% is more preferable, 30 mol% is further more preferable, and 50 mol% is all the structural units constituting the [A] polysilane. Is particularly preferred, 70 mol% is even more preferred, and 90 mol% is most preferred. The upper limit of the content ratio may be 100 mol %. By setting the content ratio of the structural unit (I) within the above range, various characteristics of the silicon-containing film can be further improved.

[Structural unit (II)]
The structural unit (II) is a structural unit represented by the following formula (2).

In the above formula (2), R ³ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ⁴ is a monovalent organic group having a ring structure and having 3 to 20 carbon atoms.

The monovalent organic group having 1 to 20 carbon atoms represented by R ³ is, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a divalent hetero atom between carbon and carbon of the hydrocarbon group. A monovalent group (α2) containing a group, a monovalent group (β2) obtained by substituting a part or all of the hydrogen atoms of the hydrocarbon group and the group (α2) with a monovalent hetero atom-containing group, the above carbon Examples thereof include a hydrogen group, a group (α2) or a monovalent group (γ2) obtained by combining a group (β2) and a divalent hetero atom-containing group. Examples of the divalent and monovalent hetero atom-containing groups include the same groups as the groups exemplified as the divalent and monovalent hetero atom-containing groups in the organic groups of R ¹ and R ² .

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 6 carbon atoms. Examples include monovalent aromatic hydrocarbon groups of 20 to 20.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include the same groups as the monovalent chain hydrocarbon group having 1 to 20 carbon atoms exemplified as R ¹ and R ² .

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include cycloalkanes such as cyclopentane and cyclohexane, and alicyclic saturated hydrocarbons such as bridged ring saturated hydrocarbons such as norbornane, adamantane and tricyclodecane. Hydrogen, cyclopentene, cyclohexene and other cycloalkenes, norbornene, tricyclodecene and other bridged ring unsaturated hydrocarbons and other alicyclic unsaturated hydrocarbons and other alicyclic hydrocarbons, excluding one hydrogen atom Groups and the like.

The monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms is, for example, one on the aromatic ring or alkyl group of an arene such as benzene, toluene, ethylbenzene, xylene, naphthalene, methylnaphthalene, anthracene or methylanthracene. Groups excluding the hydrogen atom of

R ³ is preferably a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or 1 to 6 carbon atoms. Is more preferable, and a methyl group or an ethyl group is particularly preferable.

The “ring structure” is a concept including an alicyclic structure, an aromatic carbocyclic structure, an aliphatic heterocyclic structure and an aromatic heterocyclic structure. Examples of the monovalent organic group having 3 to 20 carbon atoms containing a ring structure represented by R ⁴ include monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms and monovalent monovalent groups having 6 to 20 carbon atoms. An aromatic hydrocarbon group, a monovalent group (α3) containing a divalent heteroatom-containing group between carbon and carbon of the alicyclic hydrocarbon group and the aromatic hydrocarbon group, the alicyclic hydrocarbon group, Monovalent group (β3) obtained by substituting a part or all of hydrogen atoms of the aromatic hydrocarbon group and the group (α3) with a monovalent hetero atom-containing group, the alicyclic hydrocarbon group, and aromatic hydrocarbon. Examples thereof include a group, a group (α3) or a monovalent group (γ3) in which a group (β3) and a divalent hetero atom-containing group are combined. Examples of the divalent and monovalent hetero atom-containing groups include the same groups as the groups exemplified as the divalent and monovalent hetero atom-containing groups in the organic groups of R ¹ and R ² .

R ⁴ is preferably a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and a monovalent alicyclic group having 3 to 20 carbon atoms A saturated hydrocarbon group or an aryl group having 6 to 20 carbon atoms is more preferable, an aryl group having 6 to 20 carbon atoms is further preferable, and a phenyl group or a tolyl group is particularly preferable.

Examples of the structural unit (II) include structural units represented by the following formulas (2-1) to (2-6) (hereinafter, also referred to as “structural units (II-1) to (II-6)”) and the like. Is mentioned.

The structural unit (II) is preferably the structural unit (II-1).

When the [A] polysilane has the structural unit (II), the lower limit of the content ratio of the structural unit (II) is preferably 1 mol% with respect to all the structural units constituting the [A] polysilane, and 2 mol% Is more preferable, 5 mol% is further preferable, and 10 mol% is particularly preferable. The upper limit of the content is preferably 50 mol, more preferably 40 mol%, further preferably 30 mol%, particularly preferably 20 mol%. By setting the content ratio of the structural unit (II) within the above range, various characteristics of the silicon-containing film can be further improved.

[Other structural units]
As the other structural unit, for example, a structural unit represented by (—Si(R) ₂ —) (R is independently a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms) There is) etc.

When [A] polysilane has other structural units, the upper limit of the content of the other structural units is preferably 20 mol%, more preferably 10 mol%. The lower limit of the content ratio is, for example, 0.1 mol %.

The lower limit of the polystyrene-reduced weight average molecular weight (Mw) of [A] polysilane is preferably 300, more preferably 700, further preferably 1,000, and particularly preferably 1,500. As the upper limit of the Mw, 100,000 is preferable, 10,000 is more preferable, 5,000 is further preferable, and 3,000 is particularly preferable.

As the Mw in the present specification, a GPC column (two "G2000HXL", one "G3000HXL" and one "G4000HXL" from Tosoh Corporation) is used, and a flow rate: 1.0 mL/min, an elution solvent: tetrahydrofuran, It is a value measured by gel permeation chromatography (detector: differential refractometer) using monodisperse polystyrene as a standard under analysis conditions of column temperature: 40°C.

The lower limit of the content ratio of [A] polysilane is preferably 30% by mass, more preferably 50% by mass, further preferably 80% by mass, and particularly preferably 90% by mass, based on all components other than the solvent [B]. .. The upper limit of the content ratio may be 100% by mass.

The lower limit of the content ratio of [A] polysilane in the film-forming composition is preferably 0.1% by mass, more preferably 0.5% by mass, further preferably 1% by mass, and particularly preferably 5% by mass. The upper limit of the content ratio is preferably 50% by mass, more preferably 30% by mass, further preferably 20% by mass, and particularly preferably 15% by mass. As the polysilane [A], one type or two or more types can be used.

[[A] Polysilane Synthesis Method]
The [A] polysilane includes, for example, a monomer that provides the structural unit (I) such as trichlorosilane and methyldichlorosilane, and, if necessary, a monomer that provides the structural unit (II) such as phenyldichlorosilane. , In the presence of a base such as triethylamine, after performing a dehydrohalogenation condensation polymerization reaction in a solvent such as tetrahydrofuran, the resulting polymer, in the presence of a base such as triethylamine, in a solvent such as tetrahydrofuran, methanol, ethanol It can be obtained by reacting a compound which gives a monovalent chain organic group (R ¹ ) having 1 to 20 carbon atoms.

<[B] solvent>
The solvent [B] is not particularly limited as long as it is a solvent that can dissolve or disperse the [A] polysilane and optional components contained as necessary.

Examples of the [B] solvent include alcohol solvents, ketone solvents, ether solvents, ester solvents, nitrogen-containing solvents, water and the like. As the solvent [B], one type or two or more types can be used.

Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, and iso-butanol, ethylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, etc. Examples thereof include polyhydric alcohol solvents.

Examples of the ketone-based solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-iso-butyl ketone, cyclohexanone and the like.

Examples of ether solvents include ethyl ether, iso-propyl ether, ethylene glycol dibutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, Tetrahydrofuran etc. are mentioned.

Examples of ester solvents include ethyl acetate, γ-butyrolactone, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and acetic acid. Examples include propylene glycol monoethyl ether, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, ethyl propionate, n-butyl propionate, methyl lactate, ethyl lactate and the like.

Examples of the nitrogen-containing solvent include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and the like.

Among these, ether-based solvents and/or ester-based solvents are preferable, and ether-based solvents and/or ester-based solvents having a glycol structure are more preferable because they have excellent film-forming properties.

Examples of the ether solvent and ester solvent having a glycol structure include propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol monopropyl acetate. Examples include ether and the like. Of these, propylene glycol monomethyl ether acetate is particularly preferable.

The lower limit of the content of the glycol-structured ether solvent and ester solvent in the solvent [B] is preferably 20% by mass, more preferably 60% by mass, further preferably 90% by mass, and particularly preferably 100% by mass. ..

The lower limit of the content of the [B] solvent is preferably 100 parts by mass, more preferably 200 parts by mass, further preferably 500 parts by mass, and particularly preferably 1,000 parts by mass with respect to 100 parts by mass of [A] polysilane. preferable. The upper limit of the content is preferably 100,000 parts by mass, more preferably 50,000 parts by mass, further preferably 20,000 parts by mass, particularly preferably 10,000 parts by mass.

The lower limit of the content ratio of the [B] solvent in the film-forming composition is preferably 50% by mass, more preferably 70% by mass, and further preferably 80% by mass. As a maximum of the above-mentioned content rate, 99.9 mass% is preferred and 99.5 mass% is more preferred.

<[C] siloxane compound>
The [C] siloxane compound is a compound having a Si—O bond.

Examples of the [C] siloxane compound include polysiloxane (hereinafter, also referred to as “[C1] polysiloxane”), siloxane monomer (hereinafter, also referred to as “[C2] siloxane monomer”), and the like. “Polysiloxane” refers to a polymer having a Si—O—Si bond in the main chain. “Siloxane monomer” refers to a monomer having a Si—O bond.

As the [C1] polysiloxane, for example, a structural unit represented by the following formula (3) (hereinafter, also referred to as “structural unit (A)”) and/or a structural unit represented by the following formula (4) (hereinafter, And a compound having a “structural unit (B)”.

In the above formula (3), R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 1 to 3. When m is 2 or more, R ^A's are the same or different from each other.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ^A include the same groups as those exemplified as the monovalent organic group having 1 to 20 carbon atoms for R ³ .

As R ^A , a monovalent hydrocarbon group having 1 to 20 carbon atoms is preferable, and a monovalent chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms is used. More preferably, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms is more preferable, and a methyl group or a phenyl group is particularly preferable.

As m, 1 or 2 is preferable, and 1 is more preferable.

As the lower limit of the content ratio of the structural unit (A), 1 mol% is preferable, 10 mol% is more preferable, 20 mol% is further preferable, and 30 mol% with respect to all the structural units constituting [C1] polysiloxane. % Is particularly preferred. The upper limit of the content ratio is preferably 99 mol%, more preferably 90 mol%, further preferably 80 mol%, particularly preferably 70 mol%.

As the lower limit of the content ratio of the structural unit (B), 1 mol% is preferable, 10 mol% is more preferable, 20 mol% is further preferable, and 30 mol% is based on all the structural units constituting the [C1] polysiloxane. % Is particularly preferred. The upper limit of the content ratio is preferably 99 mol%, more preferably 90 mol%, further preferably 80 mol%, particularly preferably 70 mol%.

Examples of the [C2] siloxane monomer include alkyltrialkoxysilanes such as dodecyltrimethoxysilane and hexyltriethoxysilane, and dialkyldialkoxysilanes such as didodecyldimethoxysilane and dihexyldiethoxysilane.

The lower limit of the content of the [C] siloxane compound is preferably 0.1 parts by mass, more preferably 1 part by mass, further preferably 3 parts by mass, and 10 parts by mass with respect to 100 parts by mass of the [A] polysilane. Particularly preferred. As a maximum of the above-mentioned content, 100 mass parts is preferred, 30 mass parts is more preferred, 20 mass parts is still more preferred, and 10 mass parts is especially preferred. By setting the content of the [C] siloxane compound within the above range, various characteristics of the silicon-containing film can be further improved.

<[D] acid generator>
The acid generator [D] is a component that generates an acid upon exposure or heating. When the film-forming composition contains the [D] acid generator, the condensation reaction of the [A] polysilane can be promoted even at a relatively low temperature (including normal temperature).

Examples of the acid generator [D] that generates an acid upon exposure (hereinafter, also referred to as “photo-acid generator”) include, for example, the acid generators described in paragraphs [0077] to [0081] of JP-A-2004-168748. Etc.

Further, as the [D] acid generator that generates an acid by heating (hereinafter, also referred to as “thermal acid generator”), an onium salt-based acid generator exemplified as a photoacid generator in the above patent documents, Examples include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, and alkyl sulfonates.

When the film-forming composition contains the [D] acid generator, the lower limit of the content of the [D] acid generator is preferably 0.1 part by mass relative to 100 parts by mass of the [A] polysilane. , 0.5 part by mass is more preferable, and 1 part by mass is further preferable. The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass, further preferably 5 parts by mass.

<Other optional ingredients>
Other optional components include, for example, basic compounds (including base generators), radical generators, surfactants, colloidal silica, colloidal alumina, organic polymers and the like. Each of the other optional components may be used alone or in combination of two or more.

[Basic compound]
The basic compound accelerates the curing reaction of the film forming composition, and as a result, improves the strength and the like of the formed silicon-containing film. Further, the basic compound improves the releasability of the silicon-containing film with the acidic liquid. Examples of the basic compound include a compound having a basic amino group, a base generator which generates a compound having a basic amino group by the action of an acid or the action of heat, and the like. Examples of the compound having a basic amino group include amine compounds. Examples of the base generator include amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like. Specific examples of the amine compound, the amide group-containing compound, the urea compound and the nitrogen-containing heterocyclic compound include the compounds described in paragraphs [0079] to [0082] of JP-A-2016-27370. ..

When the film-forming composition contains a basic compound, the upper limit of the content of the basic compound is preferably 50 parts by mass with respect to 100 parts by mass of [A] polysilane. The lower limit of the content is, for example, 1 part by mass.

When the film-forming composition contains a surfactant, colloidal silica, colloidal alumina and/or organic polymer, the upper limit of the content of each of these components is 100 parts by mass of [A] polysilane. On the other hand, 2 parts by mass is preferable, and 1 part by mass is more preferable. The lower limit of the content is, for example, 0.1 part by mass.

[Method for preparing film-forming composition]
As a method for preparing the film-forming composition, for example, a solution of [A] polysilane and a solvent of [B], and optional components are mixed at a predetermined ratio, and the resulting mixed solution is preferably used for the pore size. It can be prepared by filtering with a filter of 0.2 μm or less.

<Method of manufacturing semiconductor substrate>
The method for producing a semiconductor substrate includes a step of applying the film forming composition directly or indirectly to the substrate (hereinafter, also referred to as “application step”).

According to the method for manufacturing a semiconductor substrate, since the film forming composition described above is used, the embedding property, the flatness and the oxygen-based gas etching resistance are excellent, and further, the organic solvent resistance, the acid solution peeling property and the pattern formability are improved. It is possible to form an excellent silicon-containing film.

The method for manufacturing the semiconductor substrate can further include a step of etching at least a part of the silicon-containing film formed by the coating step (hereinafter, also referred to as “etching step”) after the coating step. Thereby, the silicon-containing film can be patterned.

The manufacturing method of the semiconductor substrate, after the coating step, a step of directly or indirectly applying a resist composition to the silicon-containing film formed by the coating step (hereinafter, also referred to as "resist composition coating step" And a step of exposing the resist film formed by the resist composition coating step (hereinafter, also referred to as "exposure step (I)"), and a step of developing the exposed resist film (hereinafter, " Further, a developing step (I)") and a step of etching the silicon-containing film using the resist pattern formed in the developing step (I) as a mask (hereinafter, also referred to as "silicon-containing film etching step"). Can be prepared. Thereby, the silicon-containing film can be patterned.

In the method for manufacturing a semiconductor substrate, after the coating step, a step of exposing the silicon-containing film formed by the coating step to radiation (hereinafter, also referred to as “exposure step (II)”) The method may further include a step of developing the silicon-containing film (hereinafter, also referred to as “developing step (II)”). This makes it possible to form a pattern of the silicon-containing film by exhibiting excellent pattern formability.

The manufacturing method of the semiconductor substrate, the coating step, a step of treating the silicon-containing film formed by the coating step with oxygen gas (hereinafter, also referred to as "oxygen gas treatment step"), the oxygen gas treatment step The method may further include a subsequent step of removing the silicon-containing film with an acid solution (hereinafter, also referred to as “removal step”). This makes it possible to easily remove the silicon-containing film by exhibiting excellent acid liquid removability.

The manufacturing method of the semiconductor substrate is a step of etching the substrate using the silicon-containing film as a mask after the etching step, the silicon-containing film etching step or the developing step (II) (hereinafter, also referred to as “substrate etching step”). Can be further provided. Thereby, the substrate pattern can be formed.

The semiconductor substrate manufacturing method may further include a step of directly or indirectly forming an organic underlayer film on the substrate before the coating step.
Each step will be described below.

[Organic underlayer film forming step]
In this step, the organic underlayer film is formed directly or indirectly on the substrate.

In the method of manufacturing a semiconductor substrate, when the organic underlayer film forming step is performed, the coating step described below is performed after the organic underlayer film forming step. In this case, in the coating step, the silicon-containing film is formed by coating the film forming composition on the organic underlayer film.

The above organic underlayer film is different from the silicon-containing film formed from the film forming composition. However, the organic underlayer film may contain a silicon atom. The organic underlayer film has a predetermined function (for example, antireflection) required in order to further supplement the function of the silicon-containing film and/or the resist film in the formation of the resist pattern or to obtain the function which these films do not have. Property, coating film flatness, and high etching resistance to fluorine-based gas).

Examples of the organic lower layer film include an antireflection film and the like. Examples of the antireflection film-forming composition include "NFC HM8006" by JSR Corporation.

The organic underlayer film can be formed by applying a composition for forming an organic underlayer film by a spin coating method or the like to form a coating film, and then heating.

Examples of the substrate include a silicon wafer, an insulating film of silicon oxide, silicon nitride, silicon oxynitride, polysiloxane, and the like, a resin substrate, and the like. For example, it is possible to use an interlayer insulating film such as a wafer covered with a low dielectric insulating film formed of "Black Diamond" manufactured by AMAT, "Silk" manufactured by Dow Chemical, "LKD5109" manufactured by JSR Corporation. it can. As this substrate, a substrate on which a pattern such as a wiring groove (trench) or a plug groove (via) is formed may be used.

[Coating process]
In this step, the film-forming composition is applied directly or indirectly to the substrate. By this step, a coating film of the film forming composition is formed on the substrate directly or through another layer such as an organic underlayer film. When a substrate on which a pattern is formed is used as the substrate and the film forming composition is directly applied to the pattern side of the substrate, the embedding property and the flatness of the substrate on which the pattern is formed can be exhibited. The method for applying the film forming composition is not particularly limited, and examples thereof include known methods such as spin coating.

A silicon-containing film is formed by curing a coating film formed by coating the film-forming composition on a substrate or the like, usually by exposing and/or heating.

Examples of the radiation used for the above-mentioned exposure include electromagnetic waves such as visible light, ultraviolet rays, far ultraviolet rays, X-rays and γ rays, particle beams such as electron beams, molecular beams and ion beams.

The lower limit of the temperature for heating the coating film is preferably 90°C, more preferably 150°C, even more preferably 200°C. The upper limit of the temperature is preferably 550°C, more preferably 450°C, and even more preferably 350°C. As a minimum of the average thickness of the formed silicon-containing film, 1 nm is preferable, 3 nm is more preferable, and 5 nm is further preferable. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm, even more preferably 300 nm.

The lower limit of the absorption coefficient (k value) at 193 nm of the formed silicon-containing film is preferably more than 0.2, more preferably 0.25, and even more preferably 0.3. The upper limit of the k value is preferably 1.0, more preferably 0.7, and even more preferably 0.5.

The lower limit of the water contact angle on the surface of the formed silicon-containing film is preferably 50°, more preferably 60°, even more preferably 65°. The upper limit of the water contact angle is preferably 90°, more preferably 88°, even more preferably 86°.

[Etching process]
In this step, at least a part of the silicon-containing film formed in the coating step is etched. Thereby, the silicon-containing film can be patterned.

The above etching may be dry etching or wet etching, but dry etching is preferable.

Dry etching can be performed using, for example, a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the elemental composition of the silicon-containing film to be etched, and for example, CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ or the like. Fluorine gas, chlorine gas such as Cl ₂ and BCl ₃ , oxygen gas such as O ₂ , O ₃ and H ₂ O, H ₂ , NH ₃ , CO, CH ₄ , C ₂ H ₂ and C ₂ H _4. , Reducing gases such as C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , HF, HI, HBr, HCl, NO, NH ₃ , BCl ₃ and He, N ₂ , Ar and the like. Inert gas or the like is used. These gases may be mixed and used. A fluorine-based gas is usually used for dry etching of the silicon-containing film, and a mixture of this with an oxygen-based gas and an inert gas is preferably used.

[Resist composition coating process]
In this step, the resist composition is directly or indirectly applied to the silicon-containing film formed by the above coating step. By this step, a resist film is formed on the silicon-containing film formed in the above coating step directly or through another layer.

Examples of the resist composition include a radiation-sensitive resin composition (chemically amplified resist composition) containing a polymer having an acid-dissociable group and a radiation-sensitive acid generator, an alkali-soluble resin and a quinonediazide-based photosensitizer. And a negative resist composition containing an alkali-soluble resin and a crosslinking agent. Among these, the radiation sensitive resin composition is preferable. When the radiation-sensitive resin composition is used, a positive type pattern can be formed by developing with an alkali developing solution, and a negative type pattern can be formed by developing with an organic solvent developing solution. A double patterning method, a double exposure method or the like, which is a method of forming a fine pattern, may be appropriately used for forming the resist pattern.

The polymer contained in the radiation-sensitive resin composition is, for example, a structural unit containing an lactone structure, a cyclic carbonate structure and/or a sultone structure, a structural unit containing an alcoholic hydroxyl group, in addition to the structural unit containing an acid dissociable group. It may have a structural unit containing a phenolic hydroxyl group, a structural unit containing a fluorine atom, and the like. When the polymer has a structural unit containing a phenolic hydroxyl group and/or a structural unit containing a fluorine atom, the sensitivity can be improved when extreme ultraviolet rays or electron beams are used as the radiation during exposure.

The lower limit of the content ratio of all components other than the solvent of the resist composition is preferably 0.1% by mass, and preferably 1% by mass. The upper limit of the content ratio is preferably 50% by mass, more preferably 30% by mass. As the resist composition, one obtained by filtering with a filter having a pore size of 0.2 μm can be preferably used. In the method for producing a semiconductor substrate, a commercially available resist composition can be used as it is as the resist composition.

As a coating method of the resist composition, for example, a conventional method such as a spin coating method can be mentioned. When applying the resist composition, the amount of the resist composition to be applied is adjusted so that the obtained resist film has a predetermined film thickness.

The resist film can be formed by prebaking the coating film of the resist composition to volatilize the solvent in the coating film. The pre-baking temperature is appropriately adjusted depending on the type of resist composition used and the like, but the lower limit of the pre-baking temperature is preferably 30°C, and more preferably 50°C. The upper limit of the temperature is preferably 200°C, more preferably 150°C.

[Exposure step (I)]
In this step, the resist film formed in the resist composition coating step is exposed. This exposure is performed by selectively irradiating radiation with a mask, for example. Examples of the radiation include visible rays, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays, electromagnetic waves such as X-rays and γ rays, and charged particle rays such as electron rays and α rays. Among these, far ultraviolet rays, extreme ultraviolet rays or electron beams are preferable, and extreme ultraviolet rays or electron beams are more preferable.

[Development step (I)]
In this step, the exposed resist film is developed. By this step, a resist pattern is formed on the silicon-containing film formed by the coating step directly or through another layer. The developing method may be an alkali developing method using an alkali developing solution or an organic solvent developing method using an organic solvent developing solution. In this step, a predetermined resist pattern corresponding to the photomask used in the exposure step is formed by carrying out development with various developing solutions and then preferably washing and drying.

[Silicon-containing film etching process]
In this step, after the developing step (I), the silicon-containing film is etched using the resist pattern formed by the developing step as a mask. More specifically, the silicon-containing film is patterned by one or more times of etching using the resist pattern formed in the developing step (I) as a mask.

The above etching may be dry etching or wet etching, but dry etching is preferable. The dry etching method is, for example, the same as the dry etching method in the above etching step.

[Exposure step (II)]
In this step, the silicon-containing film formed in the above coating step is exposed to radiation. This exposure is performed by selectively irradiating radiation with a mask, for example. Examples of the radiation include visible rays, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays, electromagnetic waves such as X-rays and γ rays, and charged particle rays such as electron rays and α rays. Among these, far ultraviolet rays, extreme ultraviolet rays or electron beams are preferable, and extreme ultraviolet rays or electron beams are more preferable.

[Development step (II)]
In this step, the exposed silicon-containing film is developed. By this step, the pattern of the silicon-containing film is formed. Examples of the pattern include a line and space pattern and a hole pattern. The developing method may be an alkali developing method using an alkali developing solution or an organic solvent developing method using an organic solvent developing solution, but the organic solvent developing method is preferable. In this step, a predetermined silicon-containing film pattern corresponding to the photomask used in the exposure step (II) is formed by performing development with various developers and then preferably washing and drying. According to the method for producing a semiconductor substrate, since the above-mentioned film forming composition is used, the pattern forming property of the silicon-containing film is excellent.

[Oxygen gas treatment process]
In this step, the silicon-containing film formed in the above coating step is treated with oxygen gas. This oxygen gas treatment can be performed by heating the silicon-containing film in air or the like. As a minimum of heating temperature, 100 °C is preferred and 150 °C is more preferred. As a maximum of heating temperature, 300 °C is preferred and 250 °C is more preferred. The lower limit of the heating time is preferably 50 seconds, more preferably 10 seconds. The upper limit of the heating time is preferably 1 hour, more preferably 5 minutes.

[Removal process]
In this step, the silicon-containing film after the oxygen gas treatment step is removed with an acid solution. Examples of the acidic liquid include a liquid containing acid and water, a liquid obtained by mixing acid, hydrogen peroxide and water, and the like. Examples of the acid include sulfuric acid, hydrofluoric acid, hydrochloric acid and the like. Specific examples of the acidic liquid include a liquid obtained by mixing hydrofluoric acid and water, a liquid obtained by mixing sulfuric acid, hydrogen peroxide and water, and a liquid obtained by mixing hydrochloric acid, hydrogen peroxide and water. And the like. Among these, a liquid obtained by mixing hydrofluoric acid and water is preferable.

The lower limit of the temperature in the removing step is preferably 20°C, more preferably 40°C. The upper limit of the temperature is preferably 100°C, more preferably 70°C. The lower limit of the time in the removing step is preferably 10 seconds, more preferably 1 minute. The upper limit of the above time is preferably 1 hour, more preferably 10 minutes.

[Substrate etching process]
In this step, the substrate is etched using the pattern of the silicon-containing film as a mask. More specifically, the silicon-containing film obtained in the etching step, the silicon-containing film etching step or the developing step (II) is patterned by performing one or more etchings using the pattern formed on the silicon-containing film as a mask. Get the substrate.

When the organic underlayer film is formed on the substrate, a step of etching the organic underlayer film using the pattern of the silicon-containing film as a mask is provided. A pattern is formed on the substrate by etching the substrate using the organic underlayer film pattern formed in the organic underlayer film etching step as a mask.

The etching may be dry etching or wet etching, but dry etching is preferable. Dry etching for forming a pattern on the organic underlayer film can be performed using a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected depending on the elemental composition of the silicon-containing film and the organic lower layer film to be etched, and for example, CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , SF _{6 and} other fluorine-based gases, Cl ₂ and BCl _{3 and} other chlorine-based gases, O ₂ , O ₃ , and H ₂ O and other oxygen-based gases, H ₂ , NH ₃ , CO, CH ₄ , and C ₂ H ₂ , C ₂ H ₄ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C ₃ H ₈ , HF, HI, HBr, HCl, NO, NH ₃ , BCl _{3 and} other reducing gases, He, N ₂ , an inert gas such as Ar, or the like is used, and these gases can be mixed and used. Oxygen-based gas is usually used for dry etching of the organic underlayer film using the silicon-containing film pattern as a mask.

Dry etching when etching the substrate using the organic underlayer film pattern as a mask can be performed using a known dry etching apparatus. The etching gas used for the dry etching can be appropriately selected depending on the elemental composition of the organic underlayer film and the substrate to be etched, and is similar to those exemplified as the etching gas used for the dry etching of the organic underlayer film, for example. Etching gas and the like. The etching may be performed by using different etching gases a plurality of times.

An example will be described below. In addition, the following embodiment shows an example of a typical embodiment of the present invention, and the scope of the present invention is not narrowly interpreted by this.

The weight average molecular weight (Mw), the concentration of [A] polysilane in the solution, and the average thickness of the film in this example were measured by the following methods.

[Weight average molecular weight (Mw)]
Analysis using GPC column (2 pieces of "G2000HXL", 1 piece of "G3000HXL", 1 piece of "G4000HXL" from Tosoh Corp.), flow rate: 1.0 mL/min, elution solvent: tetrahydrofuran, column temperature: 40°C Under the conditions, it was measured by gel permeation chromatography (detector: differential refractometer) using monodisperse polystyrene as a standard.

[Concentration of [A] Polysilane in Solution]
By measuring the mass of the residue after baking 0.5 g of the solution of [A] polysilane for 30 minutes at 250° C. and dividing the mass of this residue by the mass of the solution of [A] polysilane, The concentration (mass %) in the solution was calculated.

[Average thickness of silicon-containing film]
The average thickness of the silicon-containing film was measured using a spectroscopic ellipsometer (“M2000D” manufactured by JA WOLLAM).

<Synthesis of [A] Polysilane and [C] Siloxane Compound>
The monomers used for the synthesis of [A] polysilane and [C] siloxane compound are shown below.

[Synthesis Example 1] (Synthesis of polysilane (A-1))
In a reaction vessel filled with nitrogen and substituted, 27.09 g of the compound represented by the formula (H-1) and 44 g of tetrahydrofuran were added, and the mixture was ice-cooled and cooled to 5°C or lower. Next, 20.24 g of triethylamine was dissolved in 44 g of tetrahydrofuran to prepare a dropping solution. The above solution for dropping was added dropwise over 1 hour while stirring. The polymerization reaction was carried out at 40° C. for 1 hour and then at 60° C. for 1 hour, with the end of dropping being the reaction start time. After completion of the reaction, 267 g of tetrahydrofuran was added, and the polymerization reaction solution was ice-cooled and cooled to 10°C or lower. After 60.71 g of triethylamine was added to the cooled polymerization reaction liquid, 19.22 g of methanol was added dropwise from the dropping funnel over 10 minutes while stirring. The reaction was carried out at 20° C. for 1 hour, with the completion of the dropping as the reaction start time. The salt precipitated in the reaction solution was filtered off. Next, using an evaporator, tetrahydrofuran, excess triethylamine, and excess methanol in the filtrate were removed. 84 g of propylene glycol monomethyl ether acetate and 2.7 g of trimethyl orthoformate were added to the obtained residue to obtain a propylene glycol monomethyl ether acetate solution of polysilane represented by the following formula (A-1). The concentration of polysilane (A-1) in the propylene glycol monomethyl ether acetate solution was 4% by mass. The Mw of the polysilane (A-1) was 2,500.

[Synthesis Example 2] (Synthesis of polysilane (A-2))
A propylene glycol monomethyl ether acetate solution of polysilane represented by the following formula (A-2) was obtained in the same manner as in Synthesis Example 1 except that ethanol was used instead of methanol. The concentration of polysilane (A-2) in the propylene glycol monomethyl ether acetate solution was 4% by mass. The Mw of the polysilane (A-2) was 2,600.

[Synthesis Examples 3 to 5] (Synthesis of polysilanes (A-3) to (A-5))
Propylene glycol acetate of polysilane represented by the following formulas (A-3) to (A-5) in the same manner as in Synthesis Example 1 except that each type and amount of each monomer shown in Table 1 below was used. A monomethyl ether solution was obtained. "-" in Table 1 indicates that the corresponding monomer was not used. The Mw of the obtained [A] polysilane and the concentration (mass %) of the [A] polysilane in the solution are shown in Table 1 together.

[Synthesis Example 6] (Synthesis of polysilane (a-1))
In a reaction vessel filled with nitrogen, 11.95 g of sodium metal was added to 88 g of xylene, and the mixture was heated with stirring to prepare a xylene dispersion of sodium metal. With stirring, 55.00 g of the compound represented by the above formula (M-1) was added dropwise under reflux for 3 hours. The polymerization reaction was carried out under reflux for 1 hour with the completion of the dropping as the reaction start time. After completion of the reaction, 352 g of xylene was added, and the polymerization reaction solution was ice-cooled and cooled to 10°C or lower. After adding 52.62 g of triethylamine to the cooled polymerization reaction liquid, 16.66 g of methanol was added dropwise from a dropping funnel over 10 minutes while stirring. The reaction was carried out at 20° C. for 1 hour, with the end of dropping being the start time of the reaction. The salt precipitated in the reaction solution was filtered off. Next, using an evaporator, xylene, excess triethylamine and excess methanol in the filtrate were removed. To the obtained residue, 177 g of propylene glycol monomethyl ether acetate and 5.3 g of trimethyl orthoformate were added to obtain a propylene glycol monomethyl ether acetate solution of polysilane represented by the following formula (a-1). The concentration of polysilane (a-1) in the propylene glycol monomethyl ether acetate solution was 10% by mass. The Mw of the polysilane (a-1) was 2,000.

[Synthesis Example 7] (Synthesis of siloxane compound (C-1))
In a reaction vessel, 14.74 g of the compound represented by the above formula (S-1) and 9.64 g of the compound represented by the above formula (S-2) were dissolved in 64 g of propylene glycol monoethyl ether to prepare a monomer. A solution was prepared. The temperature inside the reaction vessel was set to 35° C., and 12 g of a 7.7 mass% oxalic acid aqueous solution was added dropwise over 20 minutes while stirring. The reaction was started at the end of the dropping, and the reaction was continued for 4 hours, followed by cooling to 30°C or lower. Water, alcohols produced by the reaction and excess propylene glycol monoethyl ether were removed using an evaporator to obtain a propylene glycol monoethyl ether solution of a siloxane compound represented by the following formula (C-1). The concentration of the siloxane compound (C-1) in the propylene glycol monoethyl ether solution was 11% by mass. The Mw of the siloxane compound (C-1) was 1,900.

[Synthesis Example 8] (Synthesis of siloxane compound (C-2))
A propylene glycol monoethyl ether solution of a siloxane compound represented by the following formula (C-2) was obtained in the same manner as in Synthesis Example 7, except that each type and amount of each monomer shown in Table 1 below was used. It was "-" in Table 1 indicates that the corresponding monomer was not used. The Mw of the obtained [C] siloxane compound and the concentration (mass %) of the [C] siloxane compound in the solution are also shown in Table 1.

<Preparation of film forming composition>
The solvent [B], the siloxane compound [C] and the acid generator [D] used for the preparation of the film-forming composition are shown below.

[[B] solvent]
B-1: Propylene glycol monomethyl ether acetate B-2: Propylene glycol monoethyl ether

[[C] Siloxane compound]
C-1: The siloxane compound (C-1) synthesized above
C-2: the siloxane compound (C-2) synthesized above
C-3: n-dodecyltrimethoxysilane (compound represented by the following formula (C-3))

[[D] acid generator]
D-1: 1-(4-n-butoxynaphthalen-1-yl)tetrahydrothiophenium nonafluoro-n-butane-1-sulfonate (compound represented by the following formula (D-1))

[Example 1]
1.00 parts by weight of (A-1) as [A] polysilane (excluding solvent) and 99.00 parts by weight of (B-1) as solvent [B] (included in solution of [A] polysilane (Including (B-1) as a solvent) and the resulting solution was filtered with a filter having a pore size of 0.2 μm to prepare a film-forming composition (J-1).

[Examples 2 to 14 and Comparative Examples 1 to 6]
The film forming compositions (J-2) to (J-14) and (j-1) were prepared in the same manner as in Example 1, except that the components shown in Table 2 below were used. ~(j-6) were prepared.

<Evaluation>
Using the film-forming composition prepared above, a silicon-containing film was formed by the following method. The embedding property, flatness, oxygen-based gas etching resistance, organic solvent resistance, extinction coefficient (k value), water contact angle, acid solution releasability and pattern formability of the formed silicon-containing film were evaluated by the following methods. The evaluation results are shown in Tables 3 to 5 below. "-" in Tables 3 to 5 indicates that the corresponding evaluation was not performed.

[Embedding]
The above-prepared film-forming composition was applied onto a silicon nitride substrate on which a trench pattern having a depth of 300 nm and a width of 30 nm was formed, by a spin coating method using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.). I worked. The spin-coating rotation speed was 30° C. at 30° C. after coating the above-prepared film-forming composition on a silicon wafer by the spin-coating method using the spin coater and heating at 300° C. for 60 seconds in a nitrogen atmosphere. It was the same as the case of forming a silicon-containing film having an average thickness of 200 nm by cooling for 2 seconds. Then, the substrate on which the silicon-containing film was formed was obtained by heating at 300° C. for 60 seconds in a nitrogen atmosphere and then cooling at 23° C. for 30 seconds. The cross section of the obtained substrate was observed with a scanning electron microscope (“S-4800” manufactured by Hitachi High-Technologies Corporation) to confirm the embedding property. The embeddability was evaluated as "A" (good) when no embedding failure (void) was observed and "B" (defect) when embedding failure was observed.

[Flatness]
As shown in FIG. 1, a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) was applied onto a silicon substrate 1 on which a trench pattern having a depth of 100 nm and a width of 10 μm was formed, as shown in FIG. ) Was applied by the spin coating method. The spin speed of spin coating was 23° C. after coating the prepared film-forming composition on a silicon wafer by the spin coating method using the spin coater and heating at 300° C. for 60 seconds in the atmosphere. It was the same as the case of forming a silicon-containing film having an average thickness of 200 nm by cooling for 30 seconds. Then, after heating in an air atmosphere at 300° C. for 60 seconds, it is cooled at 23° C. for 30 seconds to form a silicon-containing film 2 having an average thickness of 200 nm in the non-trench pattern portion, to obtain a substrate with a silicon-containing film. Obtained.
The cross-sectional shape of the obtained substrate was observed using a scanning electron microscope (“S-4800” manufactured by Hitachi High-Technologies Corporation), and the height of the silicon-containing film 2 at the central portion b of the trench pattern and the above The difference (ΔFT) from the height at the portion a of the non-trench pattern at a position 5 μm from the end of the trench pattern was used as an index of flatness. The flatness was evaluated as “A” (good) when the ΔFT was less than 40 nm, “B” (somewhat good) when the ΔFT was 40 nm or more and less than 60 nm, and “C” (poor) when the ΔFT was 60 nm or more. .. Note that the height difference shown in FIG. 1 is exaggerated from the actual one.

<Formation of silicon-containing film>
[Examples 1 to 9 and Comparative Examples 1 to 3]
The above-prepared composition for film formation was applied onto a silicon wafer by a spin coating method using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) and heated at 300° C. for 60 seconds in a nitrogen atmosphere. After that, a silicon-containing film having an average thickness of 15 nm was formed by cooling at 23° C. for 30 seconds to obtain a substrate with a silicon-containing film having an average thickness of 15 nm.

[Oxygen gas etching resistance]
The silicon-containing film-coated substrate of the average thickness 15 nm, using an etching apparatus (Tokyo Electron Ltd. _{"Tactras-Vigus"), O 2 = 400sccm, PRESS} . =25 mT, HF RF (high-frequency power for plasma generation)=200 W, LF RF (high-frequency power for bias)=0 W, DCS=0 V, RDC (gas center flow rate ratio)=50%, etching treatment under the conditions of 60 sec, and processing The etching rate (nm/min) was calculated from the average film thickness before and after, and the oxygen-based gas etching resistance was evaluated. The oxygen-based gas etching resistance was evaluated as "A" (good) when the etching rate was less than 5.0 nm/min and "B" (poor) when the etching rate was 5.0 nm/min or more.

[Organic solvent resistance]
The substrate with a silicon-containing film having an average thickness of 15 nm was immersed in cyclohexanone (20° C. to 25° C.) for 10 seconds and then dried. The average thickness of the silicon-containing film before and after the immersion was measured. The film thickness change rate (%) when the average thickness of the silicon-containing film before immersion was T ₀ and the average thickness of the silicon-containing film after immersion was T ₁ was calculated by the following formula. The organic solvent resistance was evaluated as "A" (good) when the film thickness change rate was less than 1% and "B" (bad) when the film thickness change rate was 1% or more.
Thickness change rate (%)=|T ₁ −T ₀ |×100/T ₀

[Extinction coefficient (k value, 193 nm)]
The k value (193 nm) of the substrate with a silicon-containing film having an average thickness of 15 nm was measured using a spectroscopic ellipsometer (“M2000D” manufactured by JA WOLLAM).

[Water contact angle]
The water contact angle of the above-mentioned substrate with a silicon-containing film having an average thickness of 15 nm was measured at a temperature of 23° C. and a humidity of 45% using a contact angle meter (“DSA-10” manufactured by KRUSS). The water contact angle is the contact angle of water immediately after contacting 10 μL of water droplets on the silicon-containing film.

As can be seen from the results in Table 3, the silicon-containing film formed by the film-forming composition in the examples had good embeddability, flatness, oxygen-based gas etching resistance, and organic solvent resistance. On the other hand, the silicon-containing film formed by the film-forming composition in Comparative Example was inferior in flatness and oxygen-based gas etching resistance, and in some cases inferior in organic solvent resistance.

[Removability of acidic liquid]
With respect to the silicon-containing film having an average thickness of 15 nm, the acid liquid releasability was evaluated by the following method with and without oxygen gas treatment.

(Oxygen gas treatment)
The silicon-containing film-coated substrate was heated at 200° C. for 60 seconds in clean air.

(Removal of silicon-containing film)
The obtained substrate without oxygen gas treatment and substrate with oxygen gas treatment obtained above were immersed in a removing solution (50 mass% hydrofluoric acid/water=1/5 (volume ratio) mixed aqueous solution) heated to 50° C. for 5 minutes. did. The average thickness of the silicon-containing film after immersion was measured using a spectroscopic ellipsometer ("M2000D" manufactured by JA WOLLAM).

From the results in Table 4, it can be seen that the silicon-containing film formed by the film-forming composition in the example becomes excellent in acid solution peeling property by the oxygen gas treatment. On the other hand, it can be seen that the silicon-containing film formed from the film-forming composition in Comparative Example does not change the acid solution peeling property depending on the presence or absence of oxygen gas treatment.

[Pattern formability]
(Electron beam exposure)
The substrate with a silicon-containing film having an average thickness of 15 nm was exposed to an electron beam under the conditions of 100 μC/cm ² (output: 50 KeV, current density: 5.0 amps/cm ² ). As the device, "HL800D" manufactured by Hitachi, Ltd. was used. After the exposure, it was developed with isopropyl alcohol for 60 seconds. The cross-sectional shape of the obtained substrate was observed with a scanning electron microscope (“S-4800” manufactured by Hitachi High-Technologies Corporation), and when a 1:1 line-and-space pattern with a line width of 200 nm was formed, It was evaluated as "A" (good) and "B" (bad) when the above pattern was not formed.

(Extreme UV exposure)
The substrate with a silicon-containing film having an average thickness of 15 nm was exposed to extreme ultraviolet rays under the condition of 200 mJ/cm ² . The equipment used was the extreme ultraviolet lithography beam line of the New Subaru Synchrotron Radiation Facility, Institute of Advanced Industrial Science and Technology, University of Hyogo. After the exposure, it was developed with isopropyl alcohol for 60 seconds. The cross-sectional shape of the obtained substrate was observed with a scanning electron microscope (“S-4800” manufactured by Hitachi High-Technologies Corporation), and when a 1:1 line and space pattern with a line width of about 8 mm was formed, It was evaluated as "A" (good) and "B" (bad) when the pattern was not formed.

From the results of Table 5, the silicon-containing film formed from the film-forming composition in the Examples had good pattern formability in both electron beam exposure and extreme ultraviolet exposure. On the other hand, the silicon-containing film formed from the film-forming composition in Comparative Example had poor pattern formability.

1 Silicon substrate 2 Silicon-containing film

Claims

Contains polysilane and a solvent,
A film-forming composition in which the polysilane has two or more first structural units represented by the following formula (1).

(In the formula (1), R 1 is a hydrogen atom or a monovalent chain organic group having 1 to 20 carbon atoms. R 2 is a hydrogen atom, a hydroxy group or a monovalent chain having 1 to 20 carbon atoms. It is a chain organic group.)
The film-forming composition according to claim 1, wherein R 2 in the formula (1) is —OR A , and R A is a hydrogen atom or a monovalent chain organic group having 1 to 20 carbon atoms.
The film-forming composition according to claim 2, wherein R A is a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 20 carbon atoms.
The film-forming composition according to claim 1, claim 2 or claim 3, wherein R 1 in the above formula (1) is a hydrogen atom or a monovalent chain hydrocarbon group having 1 to 20 carbon atoms.
The film-forming composition according to any one of claims 1 to 4, wherein the polysilane further has a second structural unit represented by the following formula (2).

(In the formula (2), R 3 is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R 4 is a monovalent organic group having 3 to 20 carbon atoms and containing a ring structure. )
A method of manufacturing a semiconductor substrate, comprising a step of directly or indirectly coating the film-forming composition according to claim 1 on the substrate.
The method for producing a semiconductor substrate according to claim 6, wherein the substrate is a substrate on which a pattern is formed, and in the coating step, the film forming composition is directly coated on the pattern side of the substrate.
After the coating process,
The method for manufacturing a semiconductor substrate according to claim 6, further comprising: a step of etching at least a part of the silicon-containing film formed by the coating step.
After the coating process,
A step of directly or indirectly applying a resist composition to the silicon-containing film formed by the coating step,
A step of exposing the resist film formed by the resist composition coating step,
Developing the exposed resist film,
9. The method of manufacturing a semiconductor substrate according to claim 6, further comprising the step of etching the silicon-containing film using the resist pattern formed by the developing step as a mask.
After the coating process,
A step of exposing the silicon-containing film formed by the coating step to radiation,
9. The method for manufacturing a semiconductor substrate according to claim 6, further comprising the step of developing the exposed silicon-containing film.