JP7627431B2 - Prepolymer having a triazine skeleton, composition containing the same, method for forming a resist pattern, method for forming a circuit pattern, and method for purifying the prepolymer - Google Patents

Description

The present invention relates to a prepolymer having a triazine skeleton, a composition containing the same, a method for forming a resist pattern, a method for forming a circuit pattern, and a method for purifying the prepolymer.

In the manufacture of semiconductor devices, microfabrication is carried out by lithography using photoresist materials, but in recent years, with the increasing integration and speed of LSIs (large-scale integrated circuits), there is a demand for even finer patterns using pattern rules. In addition, the light source for lithography used in forming resist patterns has been shortened from KrF excimer lasers (248 nm) to ArF excimer lasers (193 nm), and the introduction of extreme ultraviolet light (EUV, 13.5 nm) is also expected.

However, in lithography using conventional polymer resist materials, the molecular weight is large, around 10,000 to 100,000, and the molecular weight distribution is wide, which causes roughness on the pattern surface, making it difficult to control the pattern dimensions and limiting miniaturization. Therefore, various low molecular weight resist materials have been proposed to provide resist patterns with higher resolution. Because low molecular weight resist materials have a small molecular size, they are expected to provide resist patterns with high resolution and low roughness.

Currently, various low molecular weight resist materials are known. For example, an alkaline development type negative radiation-sensitive composition using a low molecular weight polynuclear polyphenol compound as a main component (see, for example, Patent Document 1 and Patent Document 2) has been proposed, and an alkaline development type negative radiation-sensitive composition using a low molecular weight cyclic polyphenol compound as a main component (see, for example, Patent Document 3 and Non-Patent Document 1) has also been proposed as a candidate for a low molecular weight resist material having high heat resistance. In addition, it is known that polyphenol compounds, as a base compound of a resist material, can impart high heat resistance despite their low molecular weight, and are useful for improving the resolution and roughness of a resist pattern (see, for example, Non-Patent Document 2).

The inventors have also proposed a resist composition (see Patent Document 4) containing a compound of a specific structure and an organic solvent as a material that has excellent etching resistance, is soluble in a solvent, and can be used in wet processes.

In addition to the above, cyanate compounds are known as compounds that can provide highly heat-resistant materials despite their low molecular weight. Cyanate compounds cure to form triazine rings, giving rise to cured products with excellent heat resistance. However, cyanate compounds are generally highly crystalline and have low solubility in solvents, making them difficult to handle. Up until now, attempts have been made to polymerize cyanate compounds to a low degree to produce compounds with an appropriate molecular weight, thereby improving their ease of handling. However, because the triazine reaction proceeds rapidly, it is extremely difficult to adjust the molecular weight, and it has not been easy to obtain compounds with an appropriate molecular weight.

JP 2005-326838 A JP 2008-145539 A JP 2009-173623 A International Publication No. 2013/024778

T. Nakayama, M. Nomura, K. Haga, M. Ueda: Bull. Chem. Soc. Jpn. , 71, 2979 (1998) Shinji Okazaki and 22 others, "New Developments in Photoresist Material Development," CMC Publishing Co., Ltd., September 2009, pp. 211-259

In view of these circumstances, the present invention aims to provide a prepolymer that has excellent heat resistance and handleability.

The inventors have found that a prepolymer obtained by reacting a polyfunctional cyanate compound with a phenol can solve the above problems.
That is, the present invention is as follows.
[1]
A prepolymer having a triazine skeleton formed by reacting a polyfunctional cyanate compound with a phenol.
[2]
The prepolymer according to [1], wherein the polyfunctional cyanate compound is represented by the following formula (1) or formula (2).
[3]
The prepolymer according to [1], wherein the polyfunctional cyanate compound is represented by the following formula (3).
[4]
The prepolymer according to any one of [1] to [3], wherein the phenol is represented by the formula (4) described below.
[5]
The prepolymer according to [1], [2], or [4], wherein the polyfunctional cyanate compound represented by the formula (1) is represented by the formula (1-1) described below.
[6]
The prepolymer according to [1], [2], or [4], wherein the polyfunctional cyanate compound represented by the formula (2) is represented by the formula (2-1) described below.
[7]
The prepolymer according to any one of [4] to [6], wherein the phenol represented by the formula (4) is a monophenol represented by the following formula (4-1) described later.
[8]
The prepolymer according to any one of [1] to [7], having a mass average molecular weight of 400 to 10,000.
[9]
The prepolymer according to any one of [1] to [8], having a phenolic hydroxyl group at a terminal thereof.
[10]
A composition comprising the prepolymer according to any one of [1] to [9] above.
[11]
The composition according to [10], further comprising a solvent.
[12]
A resist film formed from the composition according to [10] or [11].
[13]
forming a resist film on a substrate using the composition according to [10] or [11];
exposing at least a portion of the formed resist film;
developing the exposed resist film to form a resist pattern;
A method for forming a resist pattern comprising the steps of:
[14]
A radiation-sensitive composition comprising the prepolymer according to any one of [1] to [9], a diazonaphthoquinone photoactive compound, and a solvent,
The radiation-sensitive composition has a solvent content of 20 to 99% by mass in the composition.
[15]
When the components other than the solvent are considered to be solid contents, the solid contents are
1 to 99% by weight of the prepolymer;
99 to 1% by weight of the diazonaphthoquinone photoactive compound;
and 0 to 49% by mass of other optional components.
[16]
An amorphous film obtained by spin-coating the radiation-sensitive composition according to [14] or [15].
[17]
A method for producing an amorphous film, comprising a step of forming an amorphous film on a substrate using the radiation-sensitive composition according to any one of [14] to [16].
[18]
forming a resist film on a substrate using the radiation-sensitive composition according to any one of [14] to [16];
exposing at least a portion of the formed resist film;
developing the exposed resist film to form a resist pattern.
[19]
An underlayer film for lithography formed from the composition according to [10] or [11].
[20]
A method for producing an underlayer film for lithography, comprising a step of forming an underlayer film on a substrate using the composition according to [10] or [11].
[21]
forming an underlayer film on a substrate using the composition according to [10] or [11];
forming at least one photoresist layer on the underlayer film;
irradiating predetermined areas of the photoresist layer with radiation and developing the photoresist layer to form a resist pattern;
The method for forming a resist pattern comprises the steps of:
[22]
forming an underlayer film on a substrate using the composition according to [10] or [11];
forming an intermediate layer film on the underlayer film using a resist intermediate layer film material containing silicon atoms;
forming at least one photoresist layer on the intermediate layer film;
irradiating predetermined areas of the photoresist layer with radiation and developing the photoresist layer to form a resist pattern;
a step of etching the intermediate layer film using the resist pattern as a mask to form an intermediate layer film pattern;
forming an underlayer film pattern by etching the underlayer film using the intermediate layer film pattern as an etching mask;
forming a pattern on the substrate by etching the substrate using the underlayer film pattern as an etching mask;
The pattern forming method comprises the steps of:
[23]
An optical component formed from the composition according to [10] or [11].

The present invention provides a prepolymer with excellent heat resistance and handleability.

The present invention provides a prepolymer having a triazine skeleton that is particularly useful as a film-forming material for lithography or a material for forming optical components, a composition containing the prepolymer, a method for forming a resist pattern, a method for forming an insulating film, a method for forming a circuit pattern, and a method for purifying the prepolymer. The present invention is described in detail below. In the present invention, "X to Y" includes the end values X and Y.

1. Prepolymer Having a Triazine Skeleton The prepolymer having a triazine skeleton of the present invention (hereinafter also referred to as the "prepolymer of the present invention") is a type of triazine compound obtained by reacting a polyfunctional cyanate compound with a phenol. The prepolymer of the present invention is a polymer having a flowability that is lightly polymerized and is generally called B-staged in the field of thermosetting resins.

When phenols are added as catalysts to cyanate compounds and resins and reacted in various solvents, triazine rings are formed while three-dimensionalization progresses, and the cyanate compounds and resins can be made high molecular weight while maintaining solubility in the solvent. The added phenols are involved in triazine cyclization and are incorporated into the resulting polymer, so that the polymer (prepolymer) has terminal hydroxyl groups and triazine rings, achieving both heat resistance and solubility. In conventional technology, it was necessary to form heat-resistant triazine rings by curing them with high temperature heating, but in the present invention, a polymer with triazine rings can be obtained without high temperature heating.

In resist film applications and lithography underlayer film applications, the formation method has a limit to the time that high-temperature baking can be performed, so it is useful to obtain a polymer having a triazine ring in advance.

The prepolymer of the present invention has molecular chains that extend three-dimensionally, making it difficult to express it in a general formula. The prepolymer of the present invention has, for example, the following structure:

In the above formula, Cy is a moiety derived from a polyfunctional cyanate compound, and Ph is a moiety derived from a phenol.

[Polyfunctional cyanate compound]
A polyfunctional cyanate compound is a compound having a plurality of cyanate groups. In the present invention, the polyfunctional cyanate compound is preferably a bifunctional, branched trifunctional, or linear polyfunctional (trifunctional or more) type. Each type will be described below.

1) Bifunctional Cyanate Compound The bifunctional cyanate compound is preferably represented by formula (1).

In the formula, each cyanate group is bonded to an aromatic group. X represents an oxygen atom, a sulfur atom, a single bond, or no cross-linking. When X represents no cross-linking, it means that there is no bond represented by -X-. In terms of availability of raw materials, X may be no cross-linking.

^R2 is a single bond or a divalent group having 0 to 40 carbon atoms which may contain a heteroatom. The heteroatom is an atom other than a hydrogen atom or a carbon atom, and examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and a silicon atom. From the viewpoint of the availability of raw materials, a sulfur atom, an oxygen atom, a nitrogen atom, or a silicon atom is preferred. Therefore, when ^R2 contains a heteroatom, examples of the group include an oxygen atom, a sulfur atom, a carbonyl group, a carboxy group (-C(=O)O-), a carboxy group-containing group, a carbonyl dioxide group (-OC(=O)O-), a sulfonyl group ( _-SO2- ), an amide group (-C(=O)-NH-), a -(Si(R) ₂ -O-) _h -containing group (where R is an alkyl group having 1 to 2 carbon atoms, and h is a number from 1 to 100), a hexafluoroisopropylidene group, a phthalidodiyl group, and a group derived by removing a hydrogen atom from a hydroxyl group of an aryldiol.

When ^R2 does not contain a heteroatom, ^R2 is a divalent hydrocarbon group having 1 to 40 carbon atoms. Examples of such a hydrocarbon group include linear, branched, or cyclic alkylene groups having 1 to 40 carbon atoms, and aralkylene groups having 6 to 40 carbon atoms.

Examples of the alkylene group include linear alkylene groups such as a methylene group or an ethylene group, branched alkylene groups such as an isopropylidene group, and cyclic alkylene groups such as a cyclohexylene group or an adamantanediyl group. The alkylene group may be substituted with a halogen.

Examples of the aralkylene group include a benzylene group and a fluorenediyl group. The aromatic ring in the aralkylene group may be a heterocycle, and these rings may have an alkyl group having 1 to 4 carbon atoms or a halogen atom as a substituent.

In formula (1), ^R0 is an alkyl group having 1 to 40 carbon atoms which may have a substituent, an aryl group having 6 to 40 carbon atoms which may have a substituent, an alkenyl group having 2 to 40 carbon atoms which may have a substituent, an alkynyl group having 2 to 40 carbon atoms which may have a substituent, an alkoxy group having 1 to 40 carbon atoms which may have a substituent, or an aryloxy group having 6 to 40 carbon atoms which may have a substituent.

The alkyl group may be linear, branched or cyclic, and examples thereof include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, cyclopropyl and cyclobutyl groups. These groups may have, as substituents, halogen atoms, nitro, amino, thiol, hydroxyl or groups in which the hydrogen atom of a hydroxyl group has been substituted with a dissociable group. Hereinafter, these substituents are also referred to as "specific substituents".

Examples of the aryl group include a phenyl group, a naphthalene group, and a biphenyl group. The specific substituent may be bonded to these groups.

Examples of the alkenyl group include a propenyl group and a butenyl group. The specific substituent may be bonded to these groups.

Examples of the alkynyl group include a propynyl group and a butynyl group. The specific substituent may be bonded to these groups.

Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a cyclohexyloxy group. The specific substituent may be bonded to these groups.

Examples of the aryloxy group include a phenoxy group, a naphthaleneoxy group, and a biphenyloxy group. The specific substituent may be bonded to these groups.

A dissociable group refers to a group that dissociates in the presence or absence of a catalyst, and among these, a group that can cleave in the presence of an acid to generate an alkali-soluble group is called an acid-dissociable group. Examples of alkali-soluble groups include, but are not limited to, phenolic hydroxyl groups, carboxyl groups, sulfonic acid groups, hexafluoroisopropanol groups, etc., and among these, from the viewpoint of ease of availability of introduction reagents, phenolic hydroxyl groups or carboxyl groups are preferred, and phenolic hydroxyl groups are particularly preferred. In order to enable highly sensitive and high-resolution pattern formation, it is preferable that the dissociable group has the property of undergoing a chain cleavage reaction in the presence of an acid. The dissociable group is not particularly limited, and can be appropriately selected from those proposed in, for example, hydroxystyrene resins and (meth)acrylic acid resins used in chemically amplified resist compositions for KrF and ArF. Preferred examples of the acid-dissociable group include groups selected from the group consisting of a 1-substituted ethyl group, a 1-substituted-n-propyl group, a 1-branched alkyl group, a silyl group, an acyl group, a 1-substituted alkoxymethyl group, a cyclic ether group, an alkoxycarbonyl group, and an alkoxycarbonylalkyl group, which have the property of being dissociated by an acid.

m represents the number of R ⁰ groups, each independently an integer of 0 to 9, preferably 0 to 8, more preferably 0 to 2, and even more preferably 0. p represents the number of condensed rings of the aromatic group, each independently an integer of 0 to 3, preferably 0 to 2, and more preferably 0.

Formula (1) is preferably represented by formula (1-1): In this formula, m' is an integer of 0 to 8, preferably 0 or 1, and more preferably 0. ^{R 2} and p are defined as above.

An example of a cyanate compound represented by formula (1) is shown below.

2) Branched trifunctional cyanate compound The branched trifunctional cyanate compound is preferably represented by formula (2): In this formula, X, R ⁰ , p, and m are the same as X in formula (1).

In the formula, each cyanate group is bonded to an aromatic group. ^R3 is a trivalent group having 0 to 40 carbon atoms which may contain a heteroatom. The heteroatom is as described above. The trivalent group having 0 to 40 carbon atoms may contain a double bond, but is preferably a group derived by removing three hydrogen atoms from an alkyl group. Examples of such groups include alkylidyne groups such as a methylidyne group or an ethylidyne group. Also, examples of the trivalent group include aromatic groups derived by removing three hydrogen atoms from an aromatic ring.

Formula (2) is preferably represented by formula (2-1), in which R ⁰ and p are defined as above, and m' is defined the same as m' in formula (1-1).

An example of a cyanate compound represented by formula (2) is shown below.

3) Linear Polyfunctional (Trifunctional or More) Cyanate Compound The linear polyfunctional cyanate compound is preferably represented by formula (3).

In the formula, each Ar ¹ is independently an aromatic group. An aromatic group is a group derived by removing a hydrogen atom from an aromatic compound, and the aromatic compound includes, but is not limited to, benzene, naphthalene, anthracene, biphenyl, etc. Since Ar ¹ may be different for each repeating unit, the cyanate compound may be a copolymer.

Each of R ^a is independently an alkyl group having 1 to 6 carbon atoms which may have a substituent, an aryl group having 6 to 12 carbon atoms which may have a substituent, an alkoxy group having 1 to 4 carbon atoms which may have a substituent, an aralkyl group in which an alkyl group having 1 to 6 carbon atoms which may have a substituent and an aryl group having 6 to 12 carbon atoms are bonded, or a phosphate group. The aryl group may have a substituent. r indicates the number of cyanate groups, and each is independently an integer of 0 to 3. q and R a indicate the number of R ^a , and each is "the number of bonds that can be made to Ar ¹ - (r + 2)". The number of bonds that can be made to Ar ¹ is the maximum number to which a substituent can be bonded when Ar ¹ exists as a compound and not as a group. For example, when Ar ¹ is a group derived from benzene, it is 6, when it is a group derived from naphthalene, it is 8, and when it is a group derived from biphenyl, it is 10. t is the average number of repetitions, and is in the range of 2 to 50. However, the total number of r is 3 or more.

The alkyl group in R ^a is as described for R ⁰ in formula (1), and examples thereof include those having 1 to 6 carbon atoms. The aryl group in R a is as described for R ⁰ in formula (1), and examples thereof include those having 6 to 12 carbon atoms. The alkoxy group in R ^a is as described for R 0 in formula (1 ^{), and examples thereof include those having 1 to 4 carbon atoms. The aralkyl group in R a is} as described for R ⁰ in formula (1), and examples thereof include those in which the alkyl group and the aryl group are bonded together.

When a plurality of D's are present, each independently represents a single bond or a divalent group having 0 to 50 carbon atoms which may have a heteroatom. Examples of such groups include a hydrocarbon group in which a hydrogen atom may be substituted with a heteroatom, a divalent organic group containing 1 to 10 nitrogen atoms and at least one N atom is directly bonded to Ar ¹ (for example, -N-R'-N- (where R' represents a hydrocarbon group)), a carbonyl group (-CO-), a carboxy group (-C(=O)O-), a carbonyl dioxide group (-OC(=O)O-), a sulfonyl group (-SO ₂ -), a divalent sulfur atom, or a divalent oxygen atom. D may also have a cyanate group as a substituent.

Specific examples of the hydrocarbon group in D include, but are not limited to, a methylene group, an ethylene group, a trimethylene group, a dimethylmethylene group, a cyclopentylene group, a cyclohexylene group, a trimethylcyclohexylene group, a biphenyldiyldimethylene group, a naphthalenediyldimethylene group, a (dimethyl)methylene-phenylene-(dimethyl)methylene group, a fluorenediyl group, a phthalidodiyl group, a benzylene group, a furanylmethylene group, an adamantanediyl group, etc. The hydrogen atoms in the group may be substituted with a halogen atom such as a fluorine atom or a chlorine atom, an alkoxy group such as a methoxy group or a phenoxy group, a cyano group, etc.

Examples of the organic group containing a nitrogen atom in D include, but are not limited to, a group represented by -N-R'-N- (where R' represents a hydrocarbon group), an imino group, a polyimide group, etc.

An example of a cyanate compound represented by formula (3) is shown below.

（ただし、Ａｒ^１は、上記基の２種以上の組み合わせである。）

(However, Ar ¹ is a combination of two or more of the above groups.)

[Phenols]
The phenol refers to a compound having a phenolic hydroxyl group, and is preferably represented by the formula (4). The phenol represented by the formula (4) is a compound having at least one phenolic hydroxyl group in an aromatic ring.

In the formula, Z is a single bond, a heteroatom, or a divalent hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom. The heteroatom is as described in formula (1). The divalent hydrocarbon group having 1 to 40 carbon atoms is also as described in formula (1). From the viewpoint of ease of synthesis, etc., Z is preferably a single bond, a divalent heteroatom, or the aforementioned linear, branched, or cyclic alkylene group having 1 to 40 carbon atoms, or an aralkylene group having 6 to 40 carbon atoms.

n indicates the number of repetitions and is an integer from 0 to 3, with 0 or 1 being preferred.

Each R ¹ is independently an alkyl group having 1 to 40 carbon atoms which may have a substituent, an aryl group having 6 to 40 carbon atoms which may have a substituent, an alkenyl group having 2 to 40 carbon atoms which may have a substituent, an alkoxy group having 1 to 40 carbon atoms which may have a substituent, a halogen atom, or a hydroxyl group, with the proviso that at least one R ¹ is a hydroxyl group. The aryl group, alkenyl group, and alkoxy group are as described in formula (1).

e represents the number of ^R1 , each independently being an integer of 1 to 9, preferably 1 or 2. f represents the number of condensed rings in the aromatic group, each independently being an integer of 0 to 3, preferably 0 to 2, more preferably 0.

The phenol represented by formula (4) is preferably a monophenol represented by formula (4-1), in which R ¹ , e, and f are defined as above, and the number of hydroxyl groups is one.

Specific examples of phenols represented by formula (4) include monofunctional or bifunctional compounds such as phenol, cresol, xylenol, butylphenol, amylphenol, nonylphenol, bisphenol A, tetramethylbisphenol F, bisphenol F, bisphenol S, bisphenol K, biphenol, tetramethylbiphenol, hydroquinone, methylhydroquinone, dimethylhydroquinone, trimethylhydroquinone, di-tert. butylhydroquinone, resorcinol, methylresorcinol, catechol, methylcatechol, dihydroxynaphthalene, dihydroxymethylnaphthalene, and dihydroxydimethylnaphthalene; condensates of phenols or naphthols with aldehydes; condensates of phenols or naphthols with xylylene glycol; condensates of phenols or naphthols with bismethoxymethylbiphenyl; condensates of phenols and isopropenylacetophenone; and reactants of phenols and dicyclopentadiene. These can be obtained by known methods.

In addition, a compound represented by formula (5) can be used as a phenol.

In the formula, each Y is independently an oxygen atom or a sulfur atom. Each R ⁵ is independently a 2w-valent hydrocarbon group having 1 to 30 carbon atoms. The hydrocarbon group may have a cyclic hydrocarbon group, a double bond, a heteroatom, or an aromatic group having 6 to 30 carbon atoms. w is an integer of 1 to 4. The 2w-valent hydrocarbon group is an alkylene group having 1 to 30 carbon atoms when w=1, an alkanetetrayl group having 1 to 30 carbon atoms when w=2, an alkanehexyl group having 2 to 30 carbon atoms when w=3, and an alkaneoctyl group having 3 to 30 carbon atoms when w=4. Examples of the 2w-valent hydrocarbon group include those having a linear, branched, or cyclic structure. The 2w-valent hydrocarbon group may have a cyclic hydrocarbon group, a double bond, a heteroatom, or an aromatic group having 6 to 30 carbon atoms. The cyclic hydrocarbon group also includes a bridged cyclic hydrocarbon group.

Each R ⁴ is independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a hydroxyl group. However, at least one of R ⁴ is a hydroxyl group. The alkyl group may be an alkyl group having 1 to 10 carbon atoms among those described in R ^0. The aryl group may be an aryl group having 6 to 10 carbon atoms among those described in R ^0. The alkenyl group may be an alkenyl group having 2 to 10 carbon atoms among those described in R ^0. Each v is independently an integer of 1 to 6, and w is an integer of 1 to 4. Specifically, the compound represented by formula (5) may be a compound disclosed in Japanese Patent No. 5,979,384.

Furthermore, a compound represented by formula (6) can also be used as a phenol.

In the formula, R ⁶ is a 2w-valent hydrocarbon group having 1 to 30 carbon atoms, and R ⁷ to R ¹⁰ are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a hydroxyl group. Here, at least one of R ⁹ or at least one of R ¹⁰ is a hydroxyl group. m ⁷ and m ⁸ are each independently an integer of 0 to 8, and m ⁹ and m ¹⁰ are each independently an integer of 0 to 9, but at least one of m ⁹ and m ¹⁰ is an integer of 1 to 9. w is an integer of 1 to 4. p ⁷ to p ¹⁰ are each independently an integer of 0 to 2. The 2w-valent hydrocarbon group, the alkyl group, the aryl group, the aryl group, and the alkenyl group are as described in formula (5). Specifically, the compound represented by formula (6) may be a compound disclosed in WO 2015/137486.

[Synthesis conditions]
Generally, as a curing catalyst for a cyanate compound, organic metal salts such as zinc octylate, copper octylate, manganese octylate, zinc naphthenate, copper naphthenate, manganese naphthenate, imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and derivatives such as adducts of carboxylic acids or acid anhydrides of these imidazoles are used. However, when the polyfunctional cyanate compound used in the present invention is reacted in an organic solvent using these catalysts, it becomes difficult to control the polymerization reaction rate, and precipitation occurs due to insolubilization caused by the rapid construction of a three-dimensional crosslinked structure accompanying cyclization trimerization. On the other hand, when a polyfunctional cyanate compound is reacted with a phenol in an organic solvent, three-dimensionalization proceeds while forming a triazine ring, and high molecular weight proceeds while maintaining solubility in the solvent, so that the triazine compound of the present invention is obtained. Phenols participate in this reaction as a catalyst and are incorporated into the compound produced, so they also function as reaction substrates.

[Reaction conditions]
The prepolymer of the present invention is obtained by reacting the polyfunctional cyanate compound with a phenol. The compounding ratio of the two is not limited, but it is preferable to use 0.5 to 10 equivalents of the phenol relative to the polyfunctional cyanate compound, and more preferably 0.7 to 5.0 equivalents.

The reaction temperature is not limited, but is preferably 10 to 80°C, more preferably 20 to 50°C, to avoid a rapid reaction. The reaction time is adjusted appropriately depending on the reaction temperature, but can be, for example, about 1 to 600 hours.

The reaction may be carried out without a solvent, but is preferably carried out in the presence of a solvent to avoid a rapid reaction. Any known solvent can be used, but halogenated hydrocarbons such as methylene chloride and 1,2-dichloroethane are preferred. When a solvent is used, the raw material concentration in the reaction solution (the concentration of the total amount of the polyfunctional cyanate compound and phenols) is preferably 5 to 50% by mass, more preferably 20 to 40% by mass.

[Characteristics]
The prepolymer of the present invention has excellent heat resistance because it has a triazine skeleton. Furthermore, the prepolymer of the present invention is soluble in various organic solvents (especially safe solvents) and is easy to handle. The molecular weight is not limited, but is preferably 400 to 10,000, more preferably 1,000 to 9,000, in terms of weight average molecular weight. In the present invention, the molecular weight is measured by GPC.

The prepolymer of the present invention has a curing property because it has a phenolic hydroxyl group derived from a phenol or a cyanate compound, and further a cyanate group derived from a polyfunctional cyanate compound. Therefore, it gives a cured product with excellent heat resistance and mechanical properties. From the viewpoint of curing reactivity, it is preferable that the phenolic hydroxyl group is present at the terminal of the prepolymer of the present invention. The prepolymer of the present invention may be crystalline or amorphous, but is preferably amorphous in consideration of solubility in a solvent.

[Application]
The prepolymer of the present invention has excellent solubility in organic solvents (especially safe solvents) and is therefore useful as a film-forming material for lithography.
The prepolymer of the present invention has a relatively high carbon concentration and a relatively low oxygen concentration, and therefore is useful as a lithography film that can suppress film deterioration during high-temperature baking and has excellent etching resistance to oxygen plasma etching and the like.
The prepolymer of the present invention has a high refractive index due to its high aromatic ring density, and is therefore useful as an optical part having excellent transparency and being resistant to coloration even when heat-treated. These uses are described below.

2. Composition The composition of the present invention contains the prepolymer. The composition preferably contains, in addition to the prepolymer, a solvent, an acid generator, an acid diffusion controller, or a combination thereof. In the composition, the prepolymer is also referred to as component (A). As described above, the prepolymer of the present invention is useful as a film-forming composition for lithography for forming a lithography film having excellent heat resistance and etching resistance. Specifically, the composition is useful for forming a photoresist film, an underlayer film for lithography, and a permanent resist film. The composition useful for forming a photoresist film is also referred to as a "resist composition".

[Resist Composition]
The resist composition preferably contains a solvent. The solvent is not particularly limited, but examples thereof include ethylene glycol monoalkyl ether acetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, and ethylene glycol mono-n-butyl ether acetate; ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether; propylene glycol monoalkyl ether acetates such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, and propylene glycol mono-n-butyl ether acetate; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether (PGME) and propylene glycol monoethyl ether; methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and n-amyl lactate. lactic acid esters such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, n-amyl acetate, n-hexyl acetate, methyl propionate, and ethyl propionate; aliphatic carboxylic acid esters such as methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 3-methoxy-2-methylpropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, and 3-methoxy-3-methylpropionate. Examples of the solvent include, but are not limited to, other esters such as butyl acetate, butyl 3-methoxy-3-methylbutyrate, methyl acetoacetate, methyl pyruvate, ethyl pyruvate, etc.; aromatic hydrocarbons such as toluene and xylene; ketones such as 2-heptanone, 3-heptanone, 4-heptanone, cyclopentanone (CPN), cyclohexanone (CHN), etc.; amides such as N,N-dimethylformamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc.; lactones such as γ-lactone, etc. These solvents can be used alone or in combination of two or more.

The solvent is preferably a safe solvent, more preferably at least one selected from the group consisting of PGMEA, PGME, CHN, CPN, 2-heptanone, anisole, butyl acetate, ethyl propionate and ethyl lactate, and even more preferably at least one selected from the group consisting of PGMEA, PGME and CHN.

The amount of solid components (components other than the solvent) and the amount of solvent in the resist composition are not particularly limited, but out of a total mass of 100% by mass of the solid components and the solvent, the amount is preferably 1 to 80% by mass of solid components and 20 to 99% by mass of solvent, more preferably 1 to 50% by mass of solid components and 50 to 99% by mass of solvent, even more preferably 2 to 40% by mass of solid components and 60 to 98% by mass of solvent, and particularly preferably 2 to 10% by mass of solid components and 90 to 98% by mass of solvent.

The resist composition may contain the following components as necessary.
1) Acid Generator (Component (C))
The resist composition preferably contains one or more acid generators that generate an acid directly or indirectly upon irradiation with any radiation selected from visible light, ultraviolet light, excimer laser, electron beam, extreme ultraviolet light (EUV), X-rays, and ion beams. The acid generator is not particularly limited, but for example, those described in International Publication No. 2013/024778 can be used. The acid generators can be used alone or in combination.

The amount of acid generator is preferably 0.001 to 49% by mass, more preferably 1 to 40% by mass, even more preferably 3 to 30% by mass, and particularly preferably 10 to 25% by mass, based on 100% by mass of the total mass of the solid components. This amount of acid generator makes it possible to obtain a resist film that can achieve a pattern profile with high sensitivity and low edge roughness. In processing the resist film, more fine processing is possible if an excimer laser is used instead of ultraviolet rays such as g-rays and i-rays, and even finer processing is possible if an electron beam, extreme ultraviolet rays, X-rays, or ion beams are used as high-energy rays.

2) Acid Crosslinker (Component (G))
The resist composition preferably contains one or more acid crosslinkers. The acid crosslinker is a compound capable of intramolecularly or intermolecularly crosslinking component (A) in the presence of an acid generated from an acid generator. Examples of such acid crosslinkers include compounds having one or more groups (hereinafter referred to as "crosslinkable groups") capable of crosslinking component (A).

Examples of such crosslinkable groups include, but are not limited to, (i) hydroxyalkyl groups such as hydroxy (C1-C6 alkyl groups), C1-C6 alkoxy (C1-C6 alkyl groups), and acetoxy (C1-C6 alkyl groups), or groups derived therefrom; (ii) carbonyl groups such as formyl and carboxy (C1-C6 alkyl groups), or groups derived therefrom; (iii) nitrogen-containing groups such as dimethylaminomethyl, diethylaminomethyl, dimethylolaminomethyl, diethylolaminomethyl, and morpholinomethyl; (iv) glycidyl group-containing groups such as glycidyl ether, glycidyl ester, and glycidylamino groups; (v) groups derived from aromatic groups such as C1-C6 allyloxy (C1-C6 alkyl groups), C1-C6 aralkyloxy (C1-C6 alkyl groups), such as benzyloxymethyl and benzoyloxymethyl groups; and (vi) polymerizable multiple bond-containing groups such as vinyl and isopropenyl groups. Among these, hydroxyalkyl groups and alkoxyalkyl groups are preferred, with alkoxymethyl groups being particularly preferred.

The acid crosslinking agent having the crosslinkable group is not limited, but may be, for example, one described in International Publication No. 2013/024778. The acid crosslinking agents may be used alone or in combination.

The amount of acid crosslinker is preferably 0.5 to 49% by mass, more preferably 0.5 to 40% by mass, even more preferably 1 to 30% by mass, and particularly preferably 2 to 20% by mass, based on 100% by mass of the total solid components. When the amount of acid crosslinker is 0.5% by mass or more, the effect of suppressing the solubility of the resist film in an alkaline developer is improved, and a decrease in the remaining film rate and the occurrence of swelling or meandering of the pattern can be suppressed. On the other hand, when the amount is 49% by mass or less, a decrease in the heat resistance of the resist can be suppressed.

3) Acid diffusion controller (component (E))
The resist composition may contain an acid diffusion control agent that has the effect of controlling the diffusion of the acid generated from the acid generator by radiation exposure in the resist film, thereby preventing undesirable chemical reactions in unexposed regions. Such an acid diffusion control agent improves the storage stability of the resist composition. In addition, the resolution is improved, and the line width change of the resist pattern due to the variation of the exposure time before radiation exposure and the exposure time after radiation exposure can be suppressed, so that the process stability is extremely high. Examples of such acid diffusion control agents include, but are not limited to, radiation decomposable basic compounds such as nitrogen atom-containing basic compounds, basic sulfonium compounds, and basic iodonium compounds.

The acid diffusion control agent is not particularly limited, but for example, those described in International Publication No. 2013/024778 can be used. The acid diffusion control agent can be used alone or in combination with two or more kinds. The amount of the acid diffusion control agent is preferably 0.001 to 49% by mass, more preferably 0.01 to 10% by mass, still more preferably 0.01 to 5% by mass, and particularly preferably 0.01 to 3% by mass, based on the total mass of the solid components (100% by mass). This amount of acid diffusion inhibitor can prevent a decrease in resolution, deterioration of pattern shape, dimensional fidelity, etc. Furthermore, even if the waiting time from electron beam irradiation to heating after radiation irradiation is long, the shape of the upper layer of the pattern can be prevented from deteriorating. Furthermore, when the amount is 10% by mass or less, a decrease in sensitivity, developability of unexposed parts, etc. can be prevented. Furthermore, the use of such an acid diffusion controller improves the storage stability of the resist composition and further improves resolution, and also makes it possible to suppress changes in the line width of the resist pattern due to fluctuations in the exposure time before and after radiation exposure, thereby extremely improving process stability.

4) Other components (component (F))
The resist composition can contain, as other component (F), one or more of a dissolution promoter, a dissolution controller, a sensitizer, a surfactant, an oxoacid of an organic carboxylic acid or a derivative thereof, or a phosphorus oxoacid or a derivative thereof, etc., added as necessary.
i) Dissolution promoter When the solubility of component (A) in the developer is too low, the dissolution promoter increases the solubility and appropriately increases the dissolution rate of component (A) during development. Examples of the dissolution promoter include low molecular weight phenolic compounds, such as bisphenols and tris(hydroxyphenyl)methane. These dissolution promoters can be used alone or in combination of two or more. The amount of the dissolution promoter is appropriately adjusted depending on the type of component (A) used, and is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, based on the total mass of the solid components (100% by mass).

ii) Dissolution control agent When the solubility of component (A) in the developer is too high, the dissolution control agent controls the solubility and appropriately reduces the dissolution rate during development. Such a dissolution control agent is preferably one that does not undergo chemical changes during the steps of baking, radiation exposure, development, etc. of the resist film. Examples of the dissolution control agent include, but are not limited to, aromatic hydrocarbons such as phenanthrene, anthracene, and acenaphthene; ketones such as acetophenone, benzophenone, and phenyl naphthyl ketone; and sulfones such as methyl phenyl sulfone, diphenyl sulfone, and dinaphthyl sulfone. These dissolution control agents can be used alone or in combination of two or more. The amount of the dissolution control agent is appropriately adjusted depending on the type of component (A) used, but is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, based on the total mass of the solid components (100% by mass).

iii) Sensitizer The sensitizer absorbs the energy of the irradiated radiation and transfers the energy to the acid generator (component (C)), thereby increasing the amount of acid generated and improving the apparent sensitivity of the resist. Examples of such sensitizers include, but are not limited to, benzophenones, biacetyls, pyrenes, phenothiazines, and fluorenes. These sensitizers can be used alone or in combination. The amount of the sensitizer is appropriately adjusted depending on the type of component (A) used, and is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, based on 100% by mass of the total mass of the solid components.

iv) Surfactant The surfactant improves the coatability and striation of the resist composition, the developability of the resist, etc. The surfactant may be any of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants, but nonionic surfactants are preferred. Nonionic surfactants have good affinity with the solvent used in the production of the resist composition, and are more likely to exhibit their effects. Examples of nonionic surfactants include, but are not limited to, polyoxyethylene higher alkyl ethers, polyoxyethylene higher alkyl phenyl ethers, and higher fatty acid diesters of polyethylene glycol. Examples of commercially available products include, but are not limited to, trade names such as Eftop (manufactured by Gemco), Megafac (manufactured by Dainippon Ink and Chemicals, Inc.), Fluorad (manufactured by Sumitomo 3M), Asahi Guard, Surflon (all manufactured by Asahi Glass Co., Ltd.), Pepol (manufactured by Toho Chemical Industry Co., Ltd.), KP (manufactured by Shin-Etsu Chemical Co., Ltd.), and Polyflow (manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.). The amount of the surfactant is appropriately adjusted depending on the type of component (A) used, but is preferably 0 to 49 mass%, more preferably 0 to 5 mass%, even more preferably 0 to 1 mass%, and particularly preferably 0 mass%, based on 100 mass% of the total mass of the solid components.

v) Organic carboxylic acid or phosphorus oxo acid or derivative thereof Organic carboxylic acid or phosphorus oxo acid or derivative thereof (hereinafter also referred to as "oxo acid, etc.") prevents sensitivity deterioration or improves resist pattern shape, delay stability, etc. Oxo acid, etc. may be used in combination with an acid diffusion controller or may be used alone. Suitable organic carboxylic acids include, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, etc. Phosphorus oxo acid or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester, etc., phosphoric acid or ester derivatives thereof, phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester, etc., phosphinic acid, phenylphosphinic acid, etc., phosphinic acid and ester derivatives thereof, and phosphonic acid is particularly preferred.

The oxoacids etc. can be used alone or in combination of two or more kinds. The amount of the oxoacids etc. is adjusted appropriately depending on the type of component (A) used, but is preferably 0 to 49% by mass, more preferably 0 to 5% by mass, even more preferably 0 to 1% by mass, and particularly preferably 0% by mass, based on 100% by mass of the total solid components.

vi) Additives other than dissolution promoters, dissolution controllers, sensitizers, oxoacids, etc. The resist composition may contain one or more additives other than the dissolution controllers, sensitizers, surfactants, and oxoacids, as necessary. Examples of such additives include dyes, pigments, and adhesion aids. For example, the incorporation of a dye or pigment is preferable because it can visualize the latent image of the exposed area and mitigate the effect of halation during exposure. In addition, the incorporation of an adhesion aid is preferable because it can improve adhesion to the substrate. In addition, for example, an antihalation agent, a storage stabilizer, an antifoaming agent, a shape improver, etc., specifically 4-hydroxy-4'-methylchalcone, etc., may be added.

The total amount of component (F) in the resist composition is 0 to 99 mass%, preferably 0 to 49 mass%, more preferably 0 to 10 mass%, even more preferably 0 to 5 mass%, even more preferably 0 to 1 mass%, and particularly preferably 0 mass%, of the total mass of the solid components (100 mass%).

5) Proportion of Each Component There are no limitations on the amount of component (A) in the resist composition, but it is preferably from 50 to 99.4 mass%, more preferably from 55 to 90 mass%, even more preferably from 60 to 80 mass%, and particularly preferably from 60 to 70 mass%, of 100 mass% of the total mass of solid components (the sum of components (A) and components (C) to (F); the same applies below). When component (A) is contained in this amount, there is a tendency for the resolution to be further improved and the line edge roughness (LER) to be further reduced.

The quantitative ratio of each component in the resist composition, i.e., component (A)/acid generator (component (C))/acid crosslinker (component (G))/acid diffusion controller (component (E))/optional component (component (F)), is preferably the following, relative to the total mass of the solid components in the resist composition (100 mass %). By using these blending amounts, the sensitivity, resolution, developability, and other performance properties of the resist film tend to be further improved.
50-99.4% by mass / 0.001-49% by mass / 0.5-49% by mass / 0.001-49% by mass / 0-49% by mass,
55-90% by mass / 1-40% by mass / 0.5-40% by mass / 0.01-10% by mass / 0-5% by mass,
60-80 mass%/3-30 mass%/1-30 mass%/0.01-5 mass%/0-1 mass%, or 60-70 mass%/10-25 mass%/2-20 mass%/0.01-3 mass%/0 mass%

Furthermore, the resist composition may contain other resins in addition to those mentioned above, if necessary. Examples of such resins include, but are not limited to, novolac resins, polyvinylphenols, polyacrylic acid, polyvinyl alcohol, styrene-maleic anhydride resins, and polymers containing acrylic acid, vinyl alcohol, or vinylphenol as monomer units, or derivatives thereof. The content of the resin is not particularly limited and is appropriately adjusted depending on the type of component (A) used, but is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 0 parts by mass, relative to 100 parts by mass of component (A).

The resist composition can be prepared by any method, for example, by dissolving each component in a solvent to prepare a homogeneous solution, and then filtering the solution, if necessary, through a filter having a pore size of about 0.2 μm.

7) Physical properties of resist composition and resist film The resist composition can form an amorphous film by spin coating. The resist composition can be used in general semiconductor manufacturing processes. Depending on the type of developer used, either a positive resist pattern or a negative resist pattern can be produced.

In the case of a positive resist pattern, the dissolution rate of the amorphous film formed by spin-coating the resist composition in a developer at 23°C is preferably 5 Å/sec or less, more preferably 0.05 to 5 Å/sec, and even more preferably 0.0005 to 5 Å/sec. If the dissolution rate is 5 Å/sec or less, the film is insoluble in the developer and can be easily made into a resist. If the dissolution rate is 0.0005 Å/sec or more, the resolution tends to improve. This is presumably because the change in solubility of component (A) before and after exposure increases the contrast at the interface between the exposed portion that dissolves in the developer and the unexposed portion that does not dissolve in the developer. In addition, the effect of reducing LER and defects is easily obtained.

In the case of a negative resist pattern, the dissolution rate of the amorphous film formed by spin-coating the resist composition in a developer at 23°C is preferably 10 Å/sec or more. If the dissolution rate is 10 Å/sec or more, the film is easily soluble in a developer and is more suitable as a resist. In addition, if the dissolution rate is 10 Å/sec or more, the resolution also tends to improve. This is presumably because the micro surface portion of component (A) dissolves, reducing LER. Furthermore, it becomes easier to obtain a defect reduction effect.

The dissolution rate can be determined by immersing an amorphous film in a developer at 23°C for a predetermined period of time and measuring the film thickness before and after immersion by known methods such as visual inspection or cross-sectional observation using an ellipsometer or scanning electron microscope.

In the case of a positive resist pattern, the dissolution rate in a developer at 23°C of the portion of the amorphous film formed by spin-coating the resist composition of the present invention that has been exposed to radiation such as a KrF excimer laser, extreme ultraviolet light, electron beam or X-ray (hereinafter also referred to as the "dissolution rate of the exposed portion") is preferably 10 Å/sec or more. If the dissolution rate is 10 Å/sec or more, the film is easily soluble in a developer and is more suitable as a resist. In addition, if the dissolution rate is 10 Å/sec or more, the resolution tends to improve. This is presumably because the micro surface portion of component (A) dissolves, reducing the LER. In addition, the effect of reducing defects is more easily obtained.

In the case of a negative resist pattern, the dissolution rate of the exposed portion of the amorphous film formed by spin-coating the resist composition of the present invention is preferably 5 Å/sec or less, more preferably 0.05 to 5 Å/sec, and even more preferably 0.0005 to 5 Å/sec. If the dissolution rate is 5 Å/sec or less, the film is insoluble in the developer and can be easily made into a resist. If the dissolution rate is 0.0005 Å/sec or more, the resolution tends to improve. This is presumably because the change in solubility of component (A) before and after exposure increases the contrast at the interface between the unexposed portion that dissolves in the developer and the exposed portion that does not dissolve in the developer. In addition, the effect of reducing LER and defects is easily obtained.

8) Permanent resist film The resist film formed from the resist composition is suitable as a permanent film that remains in the final product. Specific examples of permanent films include solder resist, packaging materials, underfill materials, package adhesive layers for circuit elements, and adhesive layers between integrated circuit elements and circuit boards in semiconductor devices, and thin film transistor protective films, liquid crystal color filter protective films, black matrices, spacers, and the like in thin display devices. The permanent resist film has the excellent advantages of being excellent in heat resistance and moisture resistance, and being less susceptible to contamination by sublimation components. The permanent resist film is a material that combines high sensitivity, high heat resistance, and moisture absorption reliability, which is important for display materials and reduces image quality degradation due to contamination.

[Radiation sensitive composition]
The radiation-sensitive composition of the present invention contains component (A), diazonaphthoquinone photoactive compound (B), and a solvent, and the amount of the solvent in the composition is 20 to 99% by mass, and the amount of components other than the solvent (solid content) is 1 to 80% by mass. The radiation-sensitive composition is useful as a base material for a positive resist that becomes a compound that is easily soluble in a developer by exposure to g-rays, h-rays, i-rays, KrF excimer laser, ArF excimer laser, extreme ultraviolet rays, electron beams, or X-rays. Although the properties of component (A) do not change significantly due to g-rays, h-rays, i-rays, KrF excimer laser, ArF excimer laser, extreme ultraviolet rays, electron beams, or X-rays, the diazonaphthoquinone photoactive compound (component (B)), which is poorly soluble in a developer, is changed into a compound that is easily soluble, and a resist pattern can be formed by a development step. Since component (A) has a relatively low molecular weight, the roughness of the resulting resist pattern is very small.

The Tg of component (A) used in the radiation-sensitive composition is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and particularly preferably 150°C or higher. The upper limit of the Tg of component (A) is not limited, but is, for example, 400°C or lower. When the Tg of component (A) is within this range, the composition has heat resistance that can maintain the pattern shape in the semiconductor lithography process, and performance such as high resolution is improved.

The crystallization heat of component (A) used in the radiation-sensitive composition is preferably less than 20 J/g. In addition, (crystallization temperature) - (Tg) is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 100°C or higher, and particularly preferably 130°C or higher. When the crystallization heat is less than 20 J/g or (crystallization temperature) - (Tg) is within the above range, it is easy to form an amorphous film by spin-coating the radiation-sensitive composition, and the film-forming properties required for a resist can be maintained for a long period of time, which tends to improve resolution.

The crystallization heat, crystallization temperature, and Tg can be determined by differential scanning calorimetry using a Shimadzu DSC/TA-50WS. Approximately 10 mg of the sample is placed in an aluminum non-sealed container and heated to above the melting point at a rate of 20°C/min in a nitrogen gas flow (50 mL/min). After rapid cooling, the sample is heated again to above the melting point at a rate of 20°C/min in a nitrogen gas flow (30 mL/min). After further rapid cooling, the sample is heated again to 400°C at a rate of 20°C/min in a nitrogen gas flow (30 mL/min). The temperature of the midpoint of the step of the stepped baseline (where the specific heat is halved) is the glass transition temperature (Tg), and the temperature of the heat generation peak that appears afterwards is the crystallization temperature. The heat generation is calculated from the area of the region surrounded by the heat generation peak and the baseline, and is taken as the heat generation of crystallization.

It is preferable that the component (A) used in the radiation-sensitive composition has low sublimation property at normal pressure and at 100°C or less, preferably 120°C or less, more preferably 130°C or less, even more preferably 140°C or less, and particularly preferably 150°C or less. Low sublimation property means that the weight loss when held at a specific temperature for 10 minutes in thermogravimetric analysis is 10% or less, preferably 5% or less, more preferably 3% or less, even more preferably 1% or less, and particularly preferably 0.1% or less. Low sublimation property can prevent contamination of the exposure device due to outgassing during exposure. There is also a tendency to obtain a good pattern shape with low roughness.

1) Diazonaphthoquinone Photoactive Compound (Component (B))
The diazonaphthoquinone photoactive compound (B) used in the radiation-sensitive composition is a diazonaphthoquinone substance including a polymeric and a non-polymeric diazonaphthoquinone photoactive compound. In the present invention, there is no limitation so long as it is a compound generally used as a photosensitive component (photosensitizer) in a positive resist composition, and one or more kinds may be arbitrarily selected and used.

As such a photosensitizer, a compound obtained by reacting naphthoquinone diazide sulfonic acid chloride or benzoquinone diazide sulfonic acid chloride with a low molecular weight compound or a high molecular weight compound having a functional group capable of condensation reaction with the same is preferred. Here, the functional group capable of condensing with the acid chloride is not limited, but examples thereof include a hydroxyl group and an amino group, with a hydroxyl group being particularly preferred. Examples of compounds containing a hydroxyl group capable of condensing with the acid chloride are not limited, but examples thereof include hydroxyl groups such as hydroquinone, resorcinol, 2,4-dihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, and 2,2',3,4,6'-pentahydroxybenzophenone. Examples of the hydroxyphenylalkanes include benzophenones, bis(2,4-dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, bis(2,4-dihydroxyphenyl)propane, and other hydroxytriphenylmethanes, such as 4,4',3",4"-tetrahydroxy-3,5,3',5'-tetramethyltriphenylmethane and 4,4',2",3",4"-pentahydroxy-3,5,3',5'-tetramethyltriphenylmethane.

Examples of naphthoquinone diazide sulfonic acid chlorides include 1,2-naphthoquinone diazide-5-sulfonyl chloride and 1,2-naphthoquinone diazide-4-sulfonyl chloride.

2) Solvent The solvent used in the radiation-sensitive composition is selected from propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexanone (CHN), cyclopentanone (CPN), 2-heptanone, anisole, butyl acetate, ethyl propionate, or ethyl lactate. Component (A) is soluble in the solvent at 23° C. to preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. The solvent is preferably selected from PGMEA, PGME, and CHN, and component (A) is soluble in the solvent at 23° C. to 20% by mass or more, particularly preferably 20% by mass or more in PGMEA at 23° C. When component (A) has this solubility, the possibility of using the radiation-sensitive composition in the semiconductor manufacturing process in actual production is increased. The amount of the solvent in the radiation-sensitive composition is 20 to 99% by mass, preferably 50 to 99% by mass, more preferably 60 to 98% by mass, and particularly preferably 90 to 98% by mass. The amount of components other than the solvent (solid components) in the radiation-sensitive composition is 1 to 80% by mass, preferably 1 to 50% by mass, more preferably 2 to 40% by mass, and particularly preferably 2 to 10% by mass.

3) Preparation The method for preparing the radiation-sensitive composition is not limited. For example, it is preferable to prepare the radiation-sensitive composition by dissolving each component in a solvent to prepare a homogeneous solution, and then filtering the solution, as necessary, through a filter having a pore size of about 0.2 μm, for example.

4) Characteristics of the Radiation-Sensitive Composition The radiation-sensitive composition can form an amorphous film by spin coating. It can also be applied to general semiconductor manufacturing processes. Depending on the type of developer used, it is possible to produce either a positive resist pattern or a negative resist pattern.

In the case of a positive resist pattern, the dissolution rate of the amorphous film formed by spin-coating the radiation-sensitive composition in a developer at 23°C is preferably 5 Å/sec or less, more preferably 0.05 to 5 Å/sec, and even more preferably 0.0005 to 5 Å/sec. If the dissolution rate is 5 Å/sec or less, the film is insoluble in the developer and can be easily made into a resist. In addition, if the dissolution rate is 0.0005 Å/sec or more, the resolution tends to improve. This is presumably because the change in solubility of component (A) before and after exposure increases the contrast at the interface between the exposed portion that dissolves in the developer and the unexposed portion that does not dissolve in the developer. In addition, the effect of reducing LER and defects is easily obtained.

In the case of a negative resist pattern, the dissolution rate of the amorphous film formed by spin-coating the radiation-sensitive composition in a developer at 23°C is preferably 10 Å/sec or more. If the dissolution rate is 10 Å/sec or more, the film is easily soluble in the developer and is more suitable as a resist. In addition, if the dissolution rate is 10 Å/sec or more, the resolution tends to improve. This is presumably because the micro surface portion of component (A) dissolves, reducing the LER. In addition, the effect of reducing defects is easily obtained.

The dissolution rate can be determined by immersing the amorphous film in a developer at 23°C for a predetermined period of time and measuring the film thickness before and after immersion by known methods such as visual inspection, an ellipsometer, or the QCM method.

In the case of a positive resist pattern, the dissolution rate in a developer at 23°C of the part of the amorphous film formed by spin-coating the radiation-sensitive composition that has been irradiated with radiation such as KrF excimer laser, extreme ultraviolet light, electron beam or X-ray, or the part that has been exposed after heating at 20 to 500°C (hereinafter also referred to as the "dissolution rate of the exposed part") is preferably 10 Å/sec or more, more preferably 10 to 10,000 Å/sec, and even more preferably 100 to 1,000 Å/sec. If the dissolution rate is 10 Å/sec or more, it is easily soluble in a developer and is more suitable as a resist. In addition, if the dissolution rate is 10,000 Å/sec or less, the resolution tends to improve. This is presumably because the micro surface portion of component (A) dissolves, reducing LER. In addition, the effect of reducing defects is easily obtained.

In the case of a negative resist pattern, the dissolution rate of the exposed portion is preferably 5 Å/sec or less, more preferably 0.05 to 5 Å/sec, and even more preferably 0.0005 to 5 Å/sec. If the dissolution rate is 5 Å/sec or less, it is insoluble in the developer and can be easily made into a resist. In addition, if the dissolution rate is 0.0005 Å/sec or more, the resolution tends to improve. This is presumably because the change in solubility of component (A) before and after exposure increases the contrast at the interface between the unexposed portion that dissolves in the developer and the exposed portion that does not dissolve in the developer. In addition, it becomes easier to achieve a reduction in LER and a reduction in defects.

5) Other components (component (D))
The radiation-sensitive composition may contain, as necessary, a component (D) other than the components (A), (B), and the solvent. Examples of the component (D) include the above-mentioned acid generator, acid crosslinker, acid diffusion controller, dissolution promoter, dissolution controller, sensitizer, surfactant, organic carboxylic acid, phosphorus oxoacid or derivatives thereof, or combinations of these.

6) Proportion of each component in radiation-sensitive composition In the radiation-sensitive composition, the amount of component (A) is preferably 1 to 99 mass%, more preferably 5 to 95 mass%, still more preferably 10 to 90 mass%, and particularly preferably 25 to 75 mass%, of the total mass of solid components (100 mass% (total of solid components such as components (A), (B), and (D)). When the amount of component (A) is within this range, a pattern with high sensitivity and small roughness tends to be obtained.

The amount of component (B) in the radiation-sensitive composition is preferably 1 to 99 mass%, more preferably 5 to 95 mass%, even more preferably 10 to 90 mass%, and particularly preferably 25 to 75 mass%, of the total mass of the solid components (100 mass%). When the amount of component (B) is within this range, a pattern with high sensitivity and small roughness tends to be obtained.

The content ratio ((A)/(B)/(D)) of component (A), diazonaphthoquinone photoactive compound (component (B)), and optional component (D) in the solid content of the radiation-sensitive composition is preferably as follows:
1-99% by mass/99-1% by mass/0-98% by mass,
1-99% by mass/99-1% by mass/0-49% by mass,
5-95% by mass/95-5% by mass/0-49% by mass,
10-90% by mass/90-10% by mass/0-10% by mass,
20-80% by weight/80-20% by weight/0-5% by weight, or 25-75% by weight/75-25% by weight/0% by weight.

The radiation-sensitive composition may contain resins other than those mentioned above. Examples of such resins include novolac resins, polyvinylphenols, polyacrylic acid, polyvinyl alcohol, styrene-maleic anhydride resins, and polymers containing acrylic acid, vinyl alcohol, or vinylphenol as monomer units, or derivatives thereof. The amount of these resins is appropriately adjusted depending on the type of component (A) used, but is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 0 parts by mass, per 100 parts by mass of component (A).

[Underlayer film forming composition for lithography]
Among the compositions containing the prepolymer of the present invention, those suitable for forming an underlayer film for lithography are referred to as an underlayer film-forming composition for lithography. The underlayer film-forming composition for lithography contains component (A) and components such as a solvent, a crosslinking agent, or an acid generator.
The amount of the solvent in the underlayer film-forming composition for lithography is not limited, but from the viewpoints of solubility and film formation, it is preferably 100 to 10,000 parts by mass, more preferably 200 to 5,000 parts by mass, and even more preferably 200 to 1,000 parts by mass, relative to 100 parts by mass of component (A).

2) Crosslinking Agent The underlayer film forming composition for lithography may contain a crosslinking agent from the viewpoint of suppressing intermixing. The crosslinking agent is not limited, but examples thereof include epoxy compounds, amino compounds, benzoxazine compounds, acrylate compounds, melamine compounds, guanamine compounds, glycoluril compounds, urea compounds, isocyanate compounds, azide compounds, phenol compounds, cyanate compounds, and the like. Specific examples of these crosslinking agents include those described in, for example, International Publication No. 2018/016614 and International Publication No. 2013/024779. These crosslinking agents are used alone or in combination of two or more. Among these, melamine compounds, benzoxazine compounds, glycoluril compounds, or epoxy compounds are preferred, and melamine compounds and benzoxazine compounds are more preferred from the viewpoint of improving etching resistance.

The content of the crosslinking agent is not limited, but is preferably 0.1 to 100 parts by mass, more preferably 5 to 50 parts by mass, and even more preferably 10 to 40 parts by mass, per 100 parts by mass of component (A). By having the content of the crosslinking agent within the above range, the occurrence of the mixing phenomenon with the resist layer tends to be suppressed, and the anti-reflection effect tends to be enhanced, and the film formability after crosslinking tends to be improved.

3) Crosslinking Accelerator The underlayer film-forming composition for lithography may contain a crosslinking accelerator to accelerate the crosslinking reaction (curing reaction) as necessary. Examples of the crosslinking accelerator include radical polymerization initiators. Examples of the radical polymerization initiator may be photopolymerization initiators that initiate radical polymerization by light, or thermal polymerization initiators that initiate radical polymerization by heat. Examples of the radical polymerization initiator include at least one selected from the group consisting of ketone-based photopolymerization initiators, organic peroxide-based polymerization initiators, and azo-based polymerization initiators.

Such radical polymerization initiators are not particularly limited and include, for example, those described in International Publication No. 2018/016614.

4) Acid Generator The underlayer film forming composition for lithography may contain an acid generator. The acid generator is as explained in the resist composition. The amount of the acid generator is not limited, but is preferably 0.1 to 50 parts by mass, and more preferably 0.5 to 40 parts by mass, relative to 100 parts by mass of component (A). When the content of the acid generator is within the above range, the crosslinking reaction tends to be enhanced, and the occurrence of the mixing phenomenon with the resist layer tends to be suppressed.

5) Basic Compound The underlayer film-forming composition for lithography may contain a basic compound from the viewpoint of improving storage stability, etc. The basic compound plays a role of preventing a small amount of acid generated from the acid generator from proceeding with a crosslinking reaction, that is, plays a role of a quencher for the acid. Such a basic compound is not limited, but may be, for example, one described in International Publication No. 2013/024779.

The amount of the basic compound is not limited, but is preferably 0.001 to 2 parts by mass, and more preferably 0.01 to 1 part by mass, per 100 parts by mass of the film-forming material for lithography. By having the content of the basic compound within the above range, storage stability tends to be improved without excessively impairing the crosslinking reaction.

6) Other Additives The underlayer film-forming composition for lithography may contain other resins or compounds for the purpose of imparting curability by heat or light or controlling absorbance. Examples of such resins or compounds include, but are not limited to, naphthol resins, xylene resins, naphthol-modified resins, and phenol-modified resins of naphthalene resins; polyhydroxystyrene, dicyclopentadiene resins, (meth)acrylates, dimethacrylates, trimethacrylates, tetramethacrylates, vinylnaphthalene, polyacenaphthylene, and other naphthalene rings, phenanthrenequinone, fluorene, and other biphenyl rings, thiophene, indene, and other heterocyclic rings having heteroatoms, and resins not containing aromatic rings; rosin-based resins, cyclodextrins, adamantane (poly)ols, tricyclodecane (poly)ols, and derivatives thereof, and other resins or compounds containing alicyclic structures. The underlayer film-forming composition for lithography may contain known additives. Examples of known additives include, but are not limited to, heat or light curing catalysts, polymerization inhibitors, flame retardants, fillers, coupling agents, thermosetting resins, photocurable resins, dyes, pigments, thickeners, lubricants, defoamers, leveling agents, ultraviolet absorbers, surfactants, colorants, and nonionic surfactants.

[Optical component-forming composition and cured product thereof]
Among the compositions containing the prepolymer of the present invention, those suitable for forming optical parts are called optical part forming compositions. Optical parts formed from the composition are expected to have a high refractive index and high transparency, and further, are expected to have storage stability, structure forming ability (film forming ability), and heat resistance. In addition, the cured product obtained by curing the composition can be a three-dimensional crosslinked product, and coloring is suppressed by a wide range of heat treatments from low temperature to high temperature, and a high refractive index and high transparency can be expected. The refractive index and degree of transparency of the optical part are not limited, but it is preferable that the optical part has a refractive index of 1.65 to 2.00% and an extinction coefficient (transparency) of 0.001 to 0.03 at a wavelength of 633 nm. The refractive index and extinction coefficient are measured using a vacuum ultraviolet region multiple incidence angle spectroscopic ellipsometer.

The optical part forming composition may contain a solvent. The solvent may be the same as the solvent used in the lithography material composition of the present embodiment described above.

The relationship between the amount of solid components and the amount of solvent in the optical component-forming composition is not limited, but it is preferable that the solid components be 1 to 80% by mass and the solvent be 20 to 99% by mass, more preferably that the solid components be 1 to 50% by mass and the solvent be 50 to 99% by mass, even more preferably that the solid components be 2 to 40% by mass and the solvent be 60 to 98% by mass, and particularly preferably that the solid components be 2 to 10% by mass and the solvent be 90 to 98% by mass. The optical component-forming composition may also be solvent-free.

2) Amount of Each Component The optical component-forming composition may contain, as another solid component, at least one selected from the group consisting of the acid generator (component (C)), the acid crosslinker (component (G)), the acid diffusion controller (component (E)) and other components (F).

Of the total mass of solid components in the optical component-forming composition (100 mass %), the amount of component (A) is preferably 50 to 99.4 mass %, more preferably 55 to 90 mass %, even more preferably 60 to 80 mass %, and particularly preferably 60 to 70 mass %.

When the optical component-forming composition contains an acid generator (component (C)), the amount thereof is preferably 0.001 to 49 mass%, more preferably 1 to 40 mass%, even more preferably 3 to 30 mass%, and particularly preferably 10 to 25 mass%, based on 100 mass% of the total mass of the solid components. By using an acid generator within the above content range, a cured product with a higher refractive index can be obtained.

From the viewpoint of improving the strength of the cured product, it is preferable that the optical component forming composition contains one or more acid crosslinkers (component (G)). The content of the acid crosslinker is preferably 0.5 to 49 mass%, more preferably 0.5 to 40 mass%, even more preferably 1 to 30 mass%, and particularly preferably 2 to 20 mass%, of the total mass of the solid components (100 mass%). A content ratio of the acid crosslinker of 0.5 mass% or more is preferable because it can improve the effect of suppressing the solubility of the optical component forming composition in organic solvents, while a content ratio of 49 mass% or less is preferable because it can suppress a decrease in the heat resistance of the optical component forming composition.

The optical component forming composition may contain an acid diffusion control agent (component (E)). The use of the acid diffusion control agent improves the storage stability of the optical component forming composition.

The content of the acid diffusion control agent is preferably 0.001 to 49% by mass, more preferably 0.01 to 10% by mass, even more preferably 0.01 to 5% by mass, and particularly preferably 0.01 to 3% by mass, out of 100% by mass. When the content of the acid diffusion control agent is within the above range, deterioration of dimensional fidelity and the like can be further suppressed. Furthermore, by using such an acid diffusion control agent, the storage stability of the optical component forming composition is improved, the resolution is improved, and the process stability is extremely excellent.

When the optical component forming composition contains the aforementioned optional component (F), the total amount thereof is preferably 0 to 49 mass % of the total mass of the solid components, more preferably 0 to 5 mass %, even more preferably 0 to 1 mass %, and particularly preferably 0 mass %.

In the composition for forming an optical part, the contents of component (A), component (C), component (E) and component (F) are preferably as follows.
50-99.4% by mass / 0.001-49% by mass / 0.001-49% by mass / 0-49% by mass,
55-90% by mass/1-40% by mass/0.01-10% by mass/0-5% by mass
60-80% by weight/3-30% by weight/0.01-5% by weight/0-1% by weight, or 60-70% by weight/10-25% by weight/0.01-3% by weight/0% by weight.

The method for preparing the optical component-forming composition is not limited, and examples include dissolving each component in a solvent to form a homogeneous solution, and then filtering the solution, if necessary, using a filter having a pore size of about 0.2 μm.

The optical component forming composition may contain a resin to the extent that it does not impair the object of the present invention. The resin is not particularly limited, and examples thereof include novolac resin, polyvinylphenols, polyacrylic acid, polyvinyl alcohol, styrene-maleic anhydride resin, and polymers containing acrylic acid, vinyl alcohol, or vinylphenol as monomer units, or derivatives thereof. The content of the resin is not particularly limited and is appropriately adjusted depending on the type of component (A) used, but is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 0 parts by mass per 100 parts by mass of component (A).

3) Cured product The cured product is obtained by curing the optical component-forming composition, and can be used as various resins. These cured products can be used for various purposes as highly versatile materials that impart various properties such as a high melting point, a high refractive index, and high transparency. The cured products can be obtained by subjecting the compositions to light irradiation, heating, or other known methods corresponding to each composition.

These cured products can be used as various synthetic resins such as epoxy resin, polycarbonate resin, acrylic resin, etc., and furthermore, by utilizing their functionality, they can be used as optical components such as lenses and optical sheets.

3. Method for forming a film or resist pattern [Method for forming a resist pattern using a resist composition]
The method for forming a resist pattern using the resist composition of the present invention comprises the steps of forming a resist film on a substrate using the composition, exposing at least a part of the formed resist film, and developing the exposed resist film to form a resist pattern. The resist pattern can also be formed as an upper layer resist in a multi-layer process. The method for forming a resist pattern can also be used as a method for forming a permanent resist film, which will be described later.

The method of forming the resist pattern is not limited, but may be, for example, the following method. First, a resist film is formed by applying a resist composition onto a conventionally known substrate by a coating means such as spin coating, casting coating, or roll coating. The conventionally known substrate is not particularly limited, and may be, for example, a substrate for electronic components or a substrate on which a predetermined wiring pattern is formed. More specifically, but not particularly limited, may be a silicon wafer, a substrate made of metal such as copper, chromium, iron, or aluminum, or a glass substrate. The material of the wiring pattern is not particularly limited, and may be, for example, copper, aluminum, nickel, or gold. If necessary, an inorganic or organic film may be provided on the substrate. The inorganic film may be, but not particularly limited, an inorganic anti-reflective film (inorganic BARC). The organic film may be, but not particularly limited, an organic anti-reflective film (organic BARC). Surface treatment with hexamethylenedisilazane or the like may be performed.

Next, the coated substrate is heated as necessary. The heating conditions vary depending on the composition of the resist composition, etc., but are preferably 20 to 250°C, more preferably 20 to 150°C. Heating is preferable because it may improve the adhesion of the resist to the substrate. Next, the resist film is exposed to any radiation selected from the group consisting of visible light, ultraviolet light, excimer laser, electron beam, extreme ultraviolet (EUV), X-ray, and ion beam into the desired pattern. The exposure conditions, etc. are appropriately selected depending on the composition of the resist composition, etc. In order to stably form a high-precision fine pattern in the exposure, it is preferable to heat after radiation exposure.

The exposed resist film is then developed with a developer to form a desired resist pattern. As the developer, it is preferable to select a solvent having a solubility parameter (SP value) close to that of the component (A) used, and polar solvents such as ketone-based solvents, ester-based solvents, alcohol-based solvents, amide-based solvents, and ether-based solvents, hydrocarbon-based solvents, or alkaline aqueous solutions can be used. Specific examples of these developers include those described in International Publication No. WO 2018/016614.

The above solvents may be mixed in multiples, or may be mixed with other solvents or water within the range of performance. However, in order to fully achieve the effects of the present invention, it is preferable that the water content of the developer as a whole is less than 70% by mass, more preferably less than 50% by mass, even more preferably less than 30% by mass, even more preferably less than 10% by mass, and it is particularly preferable that it contains substantially no water. That is, the content of the organic solvent in the developer is preferably 30% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 100% by mass or less, even more preferably 70% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, and particularly preferably 95% by mass or more and 100% by mass or less.

As a developer, a developer containing at least one solvent selected from ketone-based solvents, ester-based solvents, alcohol-based solvents, amide-based solvents and ether-based solvents is particularly preferred, as it improves resist performance such as the resolution and roughness of the resist pattern.

If necessary, an appropriate amount of a surfactant can be added to the developer. There are no particular limitations on the surfactant, but for example, ionic or non-ionic fluorine-based or silicon-based surfactants can be used. Examples of these fluorine or silicon-based surfactants include those described in JP-A-62-36663, JP-A-61-226746, JP-A-61-226745, JP-A-62-170950, JP-A-63-34540, JP-A-7-230165, JP-A-8-62834, JP-A-9-54432, JP-A-9-5988, U.S. Pat. Nos. 5,405,720, 5,360,692, 5,529,881, 5,296,330, 5,436,098, 5,576,143, 5,294,511, and 5,824,451. Preferably, they are nonionic surfactants. The non-ionic surfactant is not particularly limited, but it is more preferable to use a fluorine-based surfactant or a silicon-based surfactant.

The amount of surfactant used is usually 0.001 to 5 mass %, preferably 0.005 to 2 mass %, and more preferably 0.01 to 0.5 mass %, relative to the total amount of the developer.

The development method is not particularly limited, but may be, for example, a method in which the substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the substrate surface by surface tension and left to stand for a certain period of time (paddle method), a method in which developer is sprayed onto the substrate surface (spray method), or a method in which developer is continuously dispensed while a developer dispensing nozzle is scanned at a constant speed onto a substrate rotating at a constant speed (dynamic dispense method). The time for developing the pattern is not limited, but is preferably 10 to 90 seconds. After the development step, a step of stopping development by replacing the solvent with another solvent may be carried out.

After development, it is preferable to include a step of washing with a rinse solution containing an organic solvent. The rinse solution used in the rinse step after development is not particularly limited as long as it does not dissolve the resist pattern hardened by crosslinking, and a solution containing a general organic solvent or water can be used. As the rinse solution, it is preferable to use a rinse solution containing at least one organic solvent selected from a hydrocarbon solvent, a ketone solvent, an ester solvent, an alcohol solvent, an amide solvent, and an ether solvent. More preferably, after development, a step of washing is performed using a rinse solution containing at least one organic solvent selected from the group consisting of a ketone solvent, an ester solvent, an alcohol solvent, and an amide solvent. More preferably, after development, a step of washing is performed using a rinse solution containing an alcohol solvent or an ester solvent. Even more preferably, after development, a step of washing is performed using a rinse solution containing a monohydric alcohol. Particularly preferably, after development, a step of washing is performed using a rinse solution containing a monohydric alcohol having 5 or more carbon atoms. The time for rinsing the pattern is not limited, but is preferably 10 to 90 seconds.

The monohydric alcohol used in the rinsing process after development includes linear, branched, and cyclic monohydric alcohols. Specific examples include, but are not limited to, 1-butanol, 2-butanol, 3-methyl-1-butanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 1-hexanol, 4-methyl-2-pentanol, 1-heptanol, 1-octanol, 2-hexanol, cyclopentanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, and 4-octanol. Particularly preferred monohydric alcohols having 5 or more carbon atoms include 1-hexanol, 2-hexanol, 4-methyl-2-pentanol, 1-pentanol, and 3-methyl-1-butanol. The above components may be mixed in combination, or may be mixed with an organic solvent other than those mentioned above.

The water content in the rinse solution is preferably 10% by weight or less, more preferably 5% by weight or less, and particularly preferably 3% by weight or less. By keeping the water content at 10% by weight or less, better development characteristics tend to be obtained. An appropriate amount of surfactant can also be added to the rinse solution.

In the rinsing process, the developed wafer is washed with a rinse solution containing the organic solvent. The method of washing is not particularly limited, but may be, for example, a method in which the rinse solution is continuously applied onto a substrate rotating at a constant speed (spin coating method), a method in which the substrate is immersed for a certain period of time in a tank filled with the rinse solution (dip method), or a method in which the rinse solution is sprayed onto the substrate surface (spray method). Among these, it is preferable to wash the substrate using the spin coating method, rotate the substrate at a rotation speed of 2000 rpm to 4000 rpm after washing, and remove the rinse solution from the substrate.

After forming the resist pattern, the patterned wiring board is obtained by etching. The etching method can be a known method such as dry etching using plasma gas or wet etching using an alkaline solution, cupric chloride solution, ferric chloride solution, etc.

After forming the resist pattern, plating can be performed. Examples of plating methods include copper plating, solder plating, nickel plating, and gold plating.

The remaining resist pattern after etching can be peeled off with an organic solvent. The organic solvent is not particularly limited, but examples thereof include PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), EL (ethyl lactate), etc. The peeling method is not limited, but examples thereof include an immersion method and a spray method. In addition, the wiring board on which the resist pattern is formed may be a multilayer wiring board and may have a small diameter through hole.

Wiring boards can also be formed by forming a resist pattern, evaporating metal in a vacuum, and then dissolving the resist pattern in a solution, i.e., by the lift-off method.

The resist pattern forming method may include an underlayer film forming step of forming an underlayer film on a substrate using an underlayer film forming composition for lithography. The forming method of this embodiment includes a photoresist layer forming step of forming at least one photoresist layer on the underlayer film formed in the underlayer film forming step, and a step of irradiating a predetermined region of the photoresist layer formed in the photoresist layer forming step with radiation and developing the photoresist layer. The resist pattern forming method of this embodiment can be used to form various patterns, but is preferably a method for forming an insulating film pattern. The underlayer film forming step will be described later.

[Underlayer film for lithography]
The method for producing the underlayer film for lithography from the film-forming composition for lithography is not limited, and a known method can be used. For example, the film-forming composition for lithography is placed on a substrate by a known coating method such as spin coating or screen printing, a printing method, or the like, and then the organic solvent is removed by volatilization or the like to form the underlayer film. When forming the underlayer film, it is preferable to perform baking in order to suppress the occurrence of a mixing phenomenon with the resist upper layer film and to promote the crosslinking reaction. In this case, the baking temperature is not limited, but is preferably 80 to 450°C, more preferably 200 to 400°C. The baking time is also not limited, but is preferably within the range of 10 to 600 seconds. The thickness of the underlayer film can be appropriately selected depending on the required performance, and is not limited, but is preferably 30 to 20,000 nm, more preferably 50 to 15,000 nm.

After preparing the underlayer film, in the case of a two-layer process, it is preferable to prepare a silicon-containing resist layer or a monolayer resist made of a hydrocarbon on the underlayer film, and in the case of a three-layer process, it is preferable to prepare a silicon-containing intermediate layer on the underlayer film and then prepare a silicon-free monolayer resist layer on the silicon-containing intermediate layer. In this case, a known photoresist material can be used to form this resist layer.

As a silicon-containing resist material for a two-layer process, from the viewpoint of oxygen gas etching resistance, a silicon atom-containing polymer such as a polysilsesquioxane derivative or a vinylsilane derivative is preferably used as the base polymer, and a positive photoresist material containing an organic solvent, an acid generator, and, if necessary, a basic compound is preferably used. Here, the silicon atom-containing polymer may be a known polymer used in this type of resist material.

As the silicon-containing intermediate layer for the three-layer process, a polysilsesquioxane-based intermediate layer is preferably used. By giving the intermediate layer the effect of an anti-reflective film, reflection tends to be effectively suppressed. For example, in a 193 nm exposure process, if a material containing many aromatic groups and having high substrate etching resistance is used as the underlayer film, the k value tends to be high and the substrate reflection tends to be high, but by suppressing reflection with the intermediate layer, the substrate reflection can be reduced to 0.5% or less. As an intermediate layer having such an anti-reflective effect, but not limited to the following, for 193 nm exposure, a polysilsesquioxane that is crosslinked by acid or heat and has a light-absorbing group having a phenyl group or a silicon-silicon bond introduced therein is preferably used.

An intermediate layer formed by Chemical Vapor Deposition (CVD) can also be used. As an intermediate layer produced by CVD that is highly effective as an anti-reflective film, for example, a SiON film is known, but is not limited to the following. In general, it is easier and more cost-effective to form an intermediate layer by a wet process such as spin coating or screen printing than by CVD. The upper layer resist in the three-layer process may be either positive or negative, and the same resist as the commonly used single layer resist can be used.

Furthermore, the underlayer film of the present invention can be used as an anti-reflective film for a normal single-layer resist or as a base material for suppressing pattern collapse. The underlayer film has excellent etching resistance for base processing, so it can also be expected to function as a hard mask for base processing.

When forming a resist layer using the photoresist material, wet processes such as spin coating and screen printing are preferably used, as in the case of forming the underlayer film. After applying the resist material by spin coating or the like, pre-baking is usually performed, and this pre-baking is preferably performed at 80 to 180°C for 10 to 300 seconds. Thereafter, exposure is performed according to a conventional method, followed by post-exposure baking (PEB) and development to obtain a resist pattern. There are no particular limitations on the thickness of the resist film, but generally, 30 to 500 nm is preferred, and 50 to 400 nm is more preferred.

The exposure light is appropriately selected depending on the photoresist material used. Generally, high energy rays with a wavelength of 300 nm or less, specifically, excimer lasers with wavelengths of 248 nm, 193 nm, and 157 nm, soft X-rays with wavelengths of 3 to 20 nm, electron beams, X-rays, etc. can be mentioned. The resist pattern formed by the above-mentioned method is one in which pattern collapse is suppressed by the underlayer film. Therefore, by using the underlayer film, a finer pattern can be obtained, and the amount of exposure required to obtain the resist pattern can be reduced.

Next, etching is performed using the obtained resist pattern as a mask. Gas etching is preferably used for etching the lower layer film in the two-layer process. Etching using oxygen gas is suitable for gas etching. In addition to oxygen gas, it is also possible to add inert gases such as He and Ar, or CO, CO ₂ , NH ₃ , SO ₂ , N ₂ , NO ₂ , and H ₂ gases. Gas etching can also be performed using only CO, CO ₂ , NH ₃ , SO ₂ , N ₂ , NO ₂ , and H ₂ gases without using oxygen gas. In particular, the latter gas is preferably used for sidewall protection to prevent undercutting of the pattern sidewall.

On the other hand, gas etching is also preferably used for etching the middle layer in the three-layer process. The gas etching can be the same as that described in the two-layer process above. In particular, the processing of the middle layer in the three-layer process is preferably performed using a fluorocarbon-based gas and a resist pattern as a mask. After that, the lower layer film can be processed by, for example, performing oxygen gas etching using the middle layer pattern as a mask as described above.

Here, when forming an inorganic hard mask intermediate layer film as the intermediate layer, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiON film) is formed by a CVD method, an ALD method, or the like. The method for forming the nitride film is not limited to the following, but for example, the methods described in JP-A-2002-334869 and WO2004/066377 can be used. A photoresist film can be formed directly on such an intermediate layer film, but an organic anti-reflective coating (BARC) may also be formed on the intermediate layer film by spin coating, and a photoresist film may be formed on top of that.

As the intermediate layer, a polysilsesquioxane-based intermediate layer is also preferably used. By giving the resist intermediate layer film an effect as an anti-reflection film, reflection tends to be effectively suppressed. Specific materials for the polysilsesquioxane-based intermediate layer are not limited to the following, but for example, those described in JP-A-2007-226170 and JP-A-2007-226204 can be used. In addition, the next etching of the substrate can also be performed by a conventional method. For example, if the substrate is SiO ₂ or SiN, etching can be performed mainly with fluorocarbon-based gas, and if p-Si, Al, or W, etching can be performed mainly with chlorine-based or bromine-based gas. When etching the substrate with fluorocarbon-based gas, the silicon-containing resist of the two-layer resist process and the silicon-containing intermediate layer of the three-layer process are stripped at the same time as the substrate is processed. On the other hand, when the substrate is etched with chlorine-based or bromine-based gas, the silicon-containing resist layer or the silicon-containing intermediate layer is stripped separately, and generally, dry etching stripping with fluorocarbon-based gas is performed after the substrate is processed.

The underlayer film of the present invention has a feature of being excellent in etching resistance of the substrate. The substrate can be appropriately selected from known ones and can be used, but is not limited to these, and examples thereof include Si, α-Si, p-Si, SiO ₂ , SiN, SiON, W, TiN, Al, etc. The substrate can also be a laminate having a processed film (substrate to be processed) on a base material (support). Examples of such processed films include various low-k films and their stopper films, such as Si, SiO ₂ , SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, and Al-Si, and films made of a material different from that of the base material (support) are usually used. The thickness of the substrate or processed film to be processed is not limited, but is usually preferably about 50 to 1,000,000 nm, and more preferably 75 to 50,000 nm.

[Pattern formation method]
The pattern forming method includes the following: an underlayer film forming step of forming an underlayer film on a substrate using the underlayer film forming composition for lithography of the present invention; an intermediate layer film forming step of forming an intermediate layer film on the underlayer film formed by the underlayer film forming step using a resist intermediate layer film material containing silicon atoms; a photoresist layer forming step of forming at least one photoresist layer on the intermediate layer film formed by the intermediate layer film forming step; a resist pattern forming step of irradiating a predetermined area of the photoresist layer formed by the photoresist layer forming step with radiation and developing it to form a resist pattern; an intermediate layer film pattern forming step of etching the intermediate layer film using the resist pattern formed by the resist pattern forming step as a mask to form an intermediate layer film pattern; an underlayer film pattern forming step of etching the underlayer film using the intermediate layer film pattern formed by the intermediate layer film pattern forming step as a mask to form an underlayer film pattern; and a substrate pattern forming step of etching the substrate using the underlayer film pattern formed by the underlayer film pattern forming step as a mask to form a pattern on the substrate. A process of forming a conductor layer can be further added to these steps to form a circuit forming method.

[Permanent resist film]
The resist permanent film of this embodiment contains the above-mentioned composition. The resist permanent film formed by applying the composition is suitable as a permanent film that remains in the final product after forming a resist pattern as necessary. Specific examples of permanent films include solder resist, packaging material, underfill material, package adhesive layer of circuit elements, etc., and adhesive layer between integrated circuit elements and circuit boards in semiconductor device-related applications, and thin film transistor protective film, liquid crystal color filter protective film, black matrix, spacer, etc. in thin display-related applications. In particular, the resist permanent film containing the composition has the excellent advantages of being excellent in heat resistance and moisture resistance, and being less susceptible to contamination by sublimation components. In particular, in display materials, the material is a material that combines high sensitivity, high heat resistance, and moisture absorption reliability with little image quality deterioration due to important contamination.

When the composition for forming an underlayer film for lithography of this embodiment is used for the purpose of forming a permanent resist film, in addition to the curing agent, various additives such as other resins, surfactants, dyes, fillers, crosslinking agents, and dissolution promoters can be added as necessary, and the composition can be dissolved in an organic solvent to form a composition for a permanent resist film.

The composition can be prepared by blending the above-mentioned components and mixing them using a stirrer or the like. In addition, when the composition contains a filler or pigment, it can be prepared by dispersing or mixing them using a dispersing device such as a dissolver, homogenizer, or triple roll mill.

4. Purification Method The purification method of the prepolymer of the present invention includes an extraction step of contacting a solution containing the prepolymer and an organic solvent that is not miscible with water with an acidic aqueous solution. Specifically, the prepolymer is dissolved in an organic solvent that is not miscible with water, and the solution is contacted with an acidic aqueous solution to perform an extraction treatment, whereby metals contained in the prepolymer are transferred to the aqueous phase, and the organic phase and the aqueous phase are separated for purification. This method can significantly reduce the content of various metals in the prepolymer of the present invention.

An organic solvent that is not arbitrarily miscible with water refers to an organic solvent that has a solubility in water of less than 50% by mass at any temperature between 20 and 90°C. From the viewpoint of productivity, the solubility is preferably less than 25% by mass. There are no limitations on the organic solvent that is not arbitrarily miscible with water, but an organic solvent that can be safely applied to the semiconductor manufacturing process is preferred. The amount of organic solvent used is usually about 1 to 100 times the mass of the prepolymer of the present invention.

Specific examples of solvents used in the purification method of the present invention include those described in International Publication WO2015/080240. These solvents may be used alone or in combination of two or more. Among these, toluene, 2-heptanone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethyl acetate, etc. are preferred, with cyclohexanone and propylene glycol monomethyl ether acetate being particularly preferred.

The acidic aqueous solution is appropriately selected from among aqueous solutions in which commonly known organic or inorganic compounds are dissolved in water. For example, those described in International Publication WO2015/080240 can be mentioned. These acidic aqueous solutions are used alone or in combination of two or more. Among these, aqueous solutions of inorganic acids such as sulfuric acid and nitric acid, or organic acids such as acetic acid, oxalic acid, tartaric acid, and citric acid are preferred, aqueous solutions of sulfuric acid, oxalic acid, tartaric acid, and citric acid are preferred, and aqueous solutions of oxalic acid are particularly preferred. Polycarboxylic acids such as oxalic acid, tartaric acid, and citric acid are coordinated to metal ions and exhibit a chelating effect, so that it is considered that they have a higher removal effect. In this case, water with a low metal content, such as ion-exchanged water, is preferably used in accordance with the purpose of the present invention.

There are no limitations on the pH of the acidic aqueous solution, but an aqueous solution with an excessively high acidity is not preferred as it may adversely affect the prepolymer of the present invention. The pH range is usually about 0 to 5, and more preferably about 0 to 3.

There are no limitations on the amount of acidic aqueous solution used, but if the amount is too small, it will be necessary to perform many extractions to remove the metals, and conversely, if the amount is too large, the total amount of liquid will increase and workability may decrease. The amount of the aqueous solution used is usually 10 to 200% by mass, and preferably 20 to 100% by mass, of the solution containing the prepolymer of the present invention and the organic solvent.

The temperature during the extraction process is usually 20 to 90°C, and preferably in the range of 30 to 80°C. The extraction operation is carried out, for example, by thoroughly mixing the two by stirring or the like, and then allowing to stand. This causes the metals contained in the prepolymer of the present invention to migrate to the aqueous phase. This process also reduces the acidity of the solution, making it possible to suppress deterioration of the prepolymer of the present invention.

The oil phase containing the prepolymer of the present invention is recovered from the mixture after the above treatment by decantation or the like. There are no limitations on the time for leaving the mixture standing, but if the time for leaving the mixture standing is too short, separation of the oil phase containing the organic solvent and the aqueous phase will not be sufficient, which is not preferable. The time for leaving the mixture standing is usually 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. The extraction treatment may be performed once or multiple times.

The recovered oil phase is preferably subjected to a washing treatment with water, i.e., an extraction treatment using water. This treatment can be carried out as described above. The oil phase obtained after washing may contain water, but this water can be easily removed by vacuum distillation or the like. If necessary, an organic solvent can be added to the oil phase to adjust the concentration of the prepolymer of the present invention. The target prepolymer can be isolated by subjecting the oil phase to known treatments such as vacuum distillation and reprecipitation.

The following examples and comparative examples are provided to further explain this embodiment, but the present embodiment is not limited to these.

The prepolymer in this embodiment was analyzed and evaluated as follows.
¹ H-NMR and ¹³ C-NMR measurements were carried out using a Bruker Advance 600II spectrometer under the following conditions.
Frequency: 400MHz
Solvent: d6-DMSO
Internal standard: TMS
Measurement temperature: 23°C

<Polystyrene equivalent molecular weight>
The weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were determined by gel permeation chromatography (GPC) analysis, and the polydispersity (Mw/Mn) was also determined.
Apparatus: Shodex GPC-101 (manufactured by Showa Denko K.K.)
Column: Agilent Technologies PLgel 5μm Mixed-C column Eluent: DMAc 1mL/min
Temperature: 40°C

<Measurement of thermal decomposition temperature>
Using an EXSTAR6000TG/DTA device manufactured by SII Nanotechnology, about 5 mg of the sample was placed in an aluminum non-sealed container and heated to 700° C. at a heating rate of 10° C./min in a nitrogen gas (30 mL/min) stream. The temperature at which a thermal weight loss of 5% by mass was observed was defined as the thermal decomposition temperature (Tg), and the heat resistance was evaluated according to the following criteria.
Evaluation A: Thermal decomposition temperature is 350° C. or higher. Evaluation B: Thermal decomposition temperature is 300° C. or higher and less than 350° C. Evaluation C: Thermal decomposition temperature is less than 300° C.

(Synthesis Example 1) Synthesis of R1-BisA-CN In a 300 mL container equipped with a stirrer, a cooling tube, and a buret, 13.9 g (50 mmol) of biscyanatophenylpropane (hereinafter referred to as BisA-CN: manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 50 mL of 1,2-dichloroethane were charged and dissolved, and slight insoluble matter remaining was removed by filtration using a membrane filter (made of PTFE, pore size 0.45 μm) to prepare a 1 M solution. 3.5 g (38 mM) of phenol was added to this solution, and the mixture was stirred at 40° C. for 7 days. After cooling, 100 mL of methanol was added, the resulting precipitate was filtered, and the collected matter was washed with methanol and then dried under reduced pressure at 40° C. to obtain a phenol-containing triazine polymer (R1-BisA-CN) represented by the following formula in a yield of 52%.
The polystyrene-equivalent molecular weights of the resulting resin were measured by the above-mentioned method, and were found to be Mn: 5,942, Mw: 8,200, and Mw/Mn: 1.38.
When ¹ H-NMR and ¹³ C-NMR measurements were performed on the obtained resinous prepolymer (hereinafter referred to as “resin”) under the above-mentioned measurement conditions, the following peaks were observed, and it was confirmed that the resin had at least the chemical structural unit of the following formula.
¹ H-NMR; δ (ppm) 9.7-9.8 (O-H), 7.0-7.9 (Ph-H)
^13C -NMR; δ(ppm) 173 (triazine ring C), 155 (C-OH)

Synthesis Example 2 Synthesis of R2-BisA-CN A phenol-containing triazine polymer (R2-BisA-CN) represented by the following formula was obtained in a yield of 52% in the same manner as in Synthesis Example 1, except that 7.4 g (40 mM) of 4,4'-biphenol was used instead of phenol and the reaction conditions were 40°C and stirring for 5 days.
The polystyrene-equivalent molecular weights of the resulting resin were measured by the above-mentioned method, and were found to be Mn: 5760, Mw: 7430, and Mw/Mn: 1.29.
The analytical results of the obtained resin are as follows, and it was confirmed that the resin had at least the chemical structural unit of the following formula:
¹ H-NMR; δ (ppm) 9.5-9.6 (O-H), 6.9-7.9 (Ph-H)
^13C -NMR; δ(ppm) 173 (triazine ring C), 155 (C-OH)

(Synthesis Example 3) Synthesis of R1-DHPE-CN In a 300 mL container equipped with a stirrer, a cooling tube, and a buret, 12.9 g (50 mmol) of biscyanatodiphenyl ether (hereinafter referred to as DHPE-CN: manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 50 mL of 1,2-dichloroethane were charged and dissolved, and the slight remaining insoluble matter was removed by filtration using a membrane filter (made of PTFE, pore size 0.45 μm) to prepare a 1 M solution. 3.5 g (38 mM) of phenol was added to this solution, and the mixture was stirred at 40 ° C. for 7 days. After cooling, 100 mL of methanol was added, the resulting precipitate was filtered, and the collected matter was washed with methanol and then dried under reduced pressure at 40 ° C. to obtain a phenol-containing triazine polymer (R1-DHPE-CN) represented by the following formula in a yield of 35%.
The polystyrene-equivalent molecular weights of the resulting resin were measured by the above-mentioned method, and were found to be Mn: 4,128, Mw: 5,493, and Mw/Mn: 1.33.
When the obtained resin was subjected to NMR measurement under the above-mentioned measurement conditions, the following peaks were observed, and it was confirmed that the resin had at least the chemical structural unit of the following formula.
¹ H-NMR; δ (ppm) 9.4-9.5 (O-H), 6.9-7.7 (Ph-H)
^13C -NMR; δ(ppm) 172 (triazine ring C), 155 (C-OH)

Synthesis Example 4 Synthesis of R2-DHPE-CN A phenol-containing triazine polymer (R2-DHPE-CN) represented by the following formula was obtained in a yield of 47% in the same manner as in Synthesis Example 3, except that 7.4 g (40 mM) of 4,4'-biphenol was used instead of phenol.
The polystyrene-equivalent molecular weights of the resulting resin were measured by the above-mentioned method, and were found to be Mn: 4,500, Mw: 6,345, and Mw/Mn: 1.41.
The analytical results of the obtained resin are as follows, and it was confirmed that the resin had at least the chemical structural unit of the following formula:
¹ H-NMR; δ (ppm) 9.2-9.3 (O-H), 6.9-7.6 (Ph-H)
^13C -NMR; δ(ppm) 173 (triazine ring C), 155 (C-OH)

(Synthesis Example 5) Synthesis of R1-TRP-CN In a 300 mL container equipped with a stirrer, a cooling tube, and a buret, 18.9 g (50 mmol) of tricyanatophenylmethane (hereinafter referred to as TRP-CN: manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 50 mL of 1,2-dichloroethane were charged and dissolved, and the slight amount of insoluble matter remaining was removed by filtration using a membrane filter (made of PTFE, pore size 0.45 μm) to prepare a 1 M solution. 3.5 g (38 mM) of phenol was added to this solution, and the mixture was stirred at 40° C. for 6 days. After cooling, 100 mL of methanol was added, and the resulting precipitate was filtered. The collected matter was washed with methanol and then dried under reduced pressure at 40° C. to obtain a phenol-containing triazine polymer (R1-TRP-CN) represented by the following formula in a yield of 39%.
The polystyrene-equivalent molecular weights of the resulting resin were measured by the above-mentioned method, and were found to be Mn: 6,978, Mw: 9,630, and Mw/Mn: 1.38.
When the obtained resin was subjected to ¹ H-NMR and ¹³ C-NMR measurements under the above-mentioned measurement conditions, the following peaks were observed, and it was confirmed that the resin had at least the chemical structural unit of the following formula.
¹ H-NMR; δ (ppm) 9.4-9.5 (O-H), 6.8-7.9 (Ph-H)
^13C -NMR; δ(ppm) 172 (triazine ring C), 154 (C-OH)

Synthesis Example 6 Synthesis of R2-TRP-CN A phenol-containing triazine polymer (R2-TRP-CN) represented by the following formula was obtained in a yield of 32% in the same manner as in Synthesis Example 5, except that 7.4 g (40 mM) of 4,4'-biphenol was used instead of phenol and the reaction conditions were 40°C and stirring for 5 days.
The polystyrene-equivalent molecular weights of the resulting resin were measured by the above-mentioned method, and were found to be Mn: 6,630, Mw: 8,620, and Mw/Mn: 1.30.
The analytical results of the obtained resin are as follows, and it was confirmed that the resin had at least the chemical structural unit of the following formula:
¹ H-NMR; δ (ppm) 9.3-9.4 (O-H), 6.8-7.9 (Ph-H)
^13C -NMR; δ(ppm) 172 (triazine ring C), 154 (C-OH)

Comparative Synthesis Example 1
A four-neck flask with a capacity of 10 L and equipped with a Dimroth condenser, a thermometer and a stirring blade, which can be opened from the bottom, was prepared. In this four-neck flask, 1.09 kg (7 mol, manufactured by Mitsubishi Gas Chemical Co., Ltd.), 2.1 kg of 40 mass% formalin aqueous solution (28 mol as formaldehyde, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 0.97 mL of 98 mass% sulfuric acid (manufactured by Kanto Chemical Co., Ltd.) were charged in a nitrogen gas flow, and the mixture was reacted for 7 hours while refluxing at 100°C under normal pressure. Thereafter, 1.8 kg of ethylbenzene (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added as a dilution solvent to the reaction solution, and after standing, the aqueous phase of the lower phase was removed. Further, neutralization and washing with water were performed, and ethylbenzene and unreacted 1,5-dimethylnaphthalene were distilled off under reduced pressure to obtain 1.25 kg of dimethylnaphthalene formaldehyde resin as a light brown solid.

Next, a four-neck flask with an internal volume of 0.5 L equipped with a Dimroth condenser, a thermometer, and a stirring blade was prepared. 100 g (0.51 mol) of the dimethylnaphthalene formaldehyde resin obtained as described above and 0.05 g of paratoluenesulfonic acid were charged into this four-neck flask under a nitrogen gas flow, and the temperature was raised to 190°C and heated for 2 hours, after which the mixture was stirred. 52.0 g (0.36 mol) of 1-naphthol was then added, and the temperature was raised to 220°C and reacted for 2 hours. After dilution with the solvent, neutralization and washing with water were performed, and the solvent was removed under reduced pressure to obtain 126.1 g of modified resin (CR-1) as a black-brown solid.

[Examples 1 to 6 and Comparative Example 1]
The heat resistance of the resins obtained in Synthesis Examples 1 to 6 and Comparative Synthesis Example 1 was evaluated, and the results are shown in Table 1.

As is clear from Table 1, the resins used in Examples 1 to 6 have good heat resistance, but the compound used in Comparative Example 1 was found to have poor heat resistance.

[Examples 7 to 12, Comparative Example 2]
(Heat resistance and resist performance)
The resins obtained in Synthesis Examples 1 to 6 were subjected to the following heat resistance test and resist performance evaluation. The results are shown in Table 2.

(Preparation of resist composition)
Using each of the above resins, resist compositions were prepared according to the formulations shown in Table 2. Of the components of the resist composition in Table 2, the acid generator (C), acid diffusion controller (E) and solvent used were as follows.
Acid Generator (C)
P-1: Triphenylbenzenesulfonium trifluoromethanesulfonate (Midori Chemical Co., Ltd.)
Acid Diffusion Controller (E)
Q-1: Trioctylamine (Tokyo Chemical Industry Co., Ltd.)
Solvent S-1: Propylene glycol monomethyl ether (Tokyo Chemical Industry Co., Ltd.)

(Method of Evaluating the Resist Performance of a Resist Composition)
A uniform resist composition was spin-coated on a clean silicon wafer, and then pre-exposure baked (PB) in an oven at 110°C to form a resist film with a thickness of 60 nm. The obtained resist film was irradiated with an electron beam in a 1:1 line-and-space setting with a 50 nm interval using an electron beam lithography device (ELS-7500, manufactured by Elionix Co., Ltd.). After the irradiation, the resist film was heated at a predetermined temperature for 90 seconds, and developed by immersing in an alkaline developer containing 2.38 mass% tetramethylammonium hydroxide (TMAH) for 60 seconds. Thereafter, the resist film was washed with ultrapure water for 30 seconds and dried to form a positive resist pattern. The lines and spaces of the formed resist pattern were observed using a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Co., Ltd.) to evaluate the reactivity of the resist composition due to electron beam irradiation.

Regarding the evaluation of the resist pattern, in Examples 7 to 12, good resist patterns were obtained by irradiating the electron beam with a 1:1 line and space setting with 50 nm intervals. Note that line edge roughness was considered good when the unevenness of the pattern was less than 50 nm. On the other hand, in Comparative Example 2, a good resist pattern could not be obtained.

In this way, when the prepolymer (resin) of the present invention was used, the heat resistance was higher and a good resist pattern shape could be obtained compared to the resin (CR-1) of Comparative Example 2, which does not satisfy the requirements. As long as the requirements of the present invention are satisfied, similar effects can be obtained with resins other than those described in the examples.

[Examples 13 to 18, Comparative Example 3]
(Preparation of Radiation-Sensitive Composition)
The components shown in Table 3 were mixed to prepare a homogeneous solution, and the homogeneous solution was then filtered through a Teflon (registered trademark) membrane filter having a pore size of 0.1 μm to prepare a radiation-sensitive composition. Each of the prepared radiation-sensitive compositions was evaluated as follows.

In Comparative Example 3, the following resist base material was used.
PHS-1: Polyhydroxystyrene Mw=8000 (Sigma-Aldrich)
As the photoactive compound (B), the following was used.
B-1: Naphthoquinone diazide photosensitizer having the following chemical formula (G) (4NT-300, Toyo Gosei Co., Ltd.)
Furthermore, the following solvents were used:
S-1: Propylene glycol monomethyl ether (Tokyo Chemical Industry Co., Ltd.)

(Evaluation of Resist Performance of Radiation-Sensitive Composition)
The radiation-sensitive composition obtained above was spin-coated on a clean silicon wafer, and then pre-exposure baked (PB) in an oven at 110°C to form a resist film with a thickness of 200 nm. The resist film was exposed to ultraviolet light using an ultraviolet exposure device (Mikasa mask aligner MA-10). The ultraviolet lamp used was an ultra-high pressure mercury lamp (relative intensity ratio of g-line: h-line: i-line: j-line = 100: 80: 90: 60). After irradiation, the resist film was heated at 110°C for 90 seconds, and developed by immersing in an alkaline developer containing 2.38% by mass of TMAH for 60 seconds. The resist film was then washed with ultra-pure water for 30 seconds and dried to form a 5 μm positive resist pattern.

The lines and spaces obtained in the formed resist pattern were observed using a scanning electron microscope (S-4800, Hitachi High-Technologies Corporation). Line edge roughness was considered good when the unevenness of the pattern was less than 50 nm.

When the radiation-sensitive compositions of Examples 13 to 18 were used, a good resist pattern with a resolution of 5 μm was obtained. In addition, the pattern had little roughness and was good.

On the other hand, when the radiation-sensitive composition in Comparative Example 3 was used, a good resist pattern with a resolution of 5 μm was obtained. However, the roughness of the pattern was significantly poor.

As described above, it was found that the radiation-sensitive compositions in Examples 13 to 18 were able to form resist patterns with less roughness and a good shape compared to the radiation-sensitive composition in Comparative Example 3. As long as they satisfy the requirements of the present invention described above, radiation-sensitive compositions other than those described in the examples also exhibit the same effects.

Furthermore, since the resins obtained in Synthesis Examples 1 to 6 have a relatively low molecular weight and low viscosity, it was evaluated that the filling characteristics and film surface flatness of the underlayer film forming material for lithography using these resins can be relatively advantageously improved. In addition, since the thermal decomposition temperature is all 350°C or higher (rating A) and they have high heat resistance, it was evaluated that they can be used even under high temperature baking conditions. In order to confirm these points, the following evaluation was carried out assuming an underlayer film application.

[Examples 19-1 to 24-2, Comparative Example 4]
(Preparation of composition for forming underlayer film for lithography)
Compositions for forming an underlayer film for lithography were prepared so as to have the compositions shown in Table 4. Next, these compositions for forming an underlayer film for lithography were spin-coated on a silicon substrate, and then baked at 240° C. for 60 seconds and then at 400° C. for 120 seconds to prepare underlayer films with a thickness of 200 nm. The acid generators, crosslinking agents, and organic solvents used were as follows.
Acid generator: di-t-Bt diphenyliodonium nonafluoromethanesulfonate (DTDPI) manufactured by Midori Chemical Co., Ltd.
Crosslinking agent: Nikalac MX270 (Nikalac) manufactured by Sanwa Chemical Co., Ltd.
Organic solvent: cyclopentanone (CPN)
Novolak: PSM4357 manufactured by Gun-ei Chemical Co., Ltd.

Next, an etching test was performed under the conditions shown below to evaluate the etching resistance. The evaluation results are shown in Table 4.

[Etching test]
Etching equipment: Samco International RIE-10NR
Output: 50W
Pressure: 20 Pa
Time: 2 minutes
Etching gas Ar gas flow rate: _CF4 gas flow rate: _O2 gas flow rate = 50:5:5 (sccm)

(Evaluation of Etching Resistance)
The etching resistance was evaluated by the following procedure. First, a novolac underlayer film was prepared under the same conditions as above, except that novolac (PSM4357 manufactured by Gun-ei Chemical Co., Ltd.) was used. The above etching test was performed on this novolac underlayer film, and the etching rate was measured.

Next, the underlayer films of Examples 19-1 to 24-2 and Comparative Example 4 were prepared under the same conditions as the underlayer film of the novolac, and the above-mentioned etching test was carried out in the same manner to measure the etching rate. The etching resistance was evaluated according to the following evaluation criteria, based on the etching rate of the underlayer film of the novolac.
[Evaluation Criteria]
A: The etching rate is less than -20% compared to the novolac underlayer film. B: The etching rate is -20% to 0% compared to the novolac underlayer film.
C: Etching rate is more than +0% compared to the underlayer film of novolac

It was found that Examples 19-1 to 24-2 exhibited superior etching rates compared to the underlayer film of novolac and the underlayer film of Comparative Example 4. On the other hand, it was found that the underlayer film of Comparative Example 4 exhibited an inferior etching rate compared to the underlayer film of novolac.

[Examples 25-1 to 30-2, Comparative Example 5]
Next, the composition for forming an underlayer film for lithography used in Examples 19-1 to 24-2 and Comparative Example 4 was applied to a SiO ₂ substrate having a film thickness of 80 nm and a 60 nm line and space, and baked at 240° C. for 60 seconds to form a 90 nm underlayer film.

(Evaluation of embeddability)
The embeddability was evaluated by the following procedure. Specifically, a cross section of the film obtained under the above conditions was cut out and observed under an electron microscope to evaluate the embeddability. The evaluation results are shown in Table 5.

[Evaluation Criteria]
A: The lower layer film is embedded without any defects in the uneven portions of the 60 nm line and space _SiO2 substrate.
C: There are defects in the uneven parts of the 60 nm line and space _SiO2 substrate, and the underlayer film is not filled in.

It was found that the filling properties were good in Examples 25-1 to 30-2, whereas in Comparative Example 5, defects were observed in the uneven portions of the _SiO2 substrate, and it was found that the filling properties were poor.

[Examples 31-1 to 36-2]
Next, the composition for forming an underlayer film for lithography used in Examples 19-1 to 24-2 was applied onto a _SiO2 substrate having a thickness of 300 nm, and baked at 240° C. for 60 seconds and then at 400° C. for 120 seconds to form an underlayer film having a thickness of 85 nm. An ArF resist solution was applied onto this underlayer film, and baked at 130° C. for 60 seconds to form a photoresist layer having a thickness of 140 nm.

The ArF resist solution used was prepared by mixing 5 parts by weight of the compound of the following formula (16), 1 part by weight of triphenylsulfonium nonafluoromethanesulfonate, 2 parts by weight of tributylamine, and 92 parts by weight of PGMEA.

The compound of the following formula (16) was prepared as follows. That is, 4.15 g of 2-methyl-2-methacryloyloxyadamantane, 3.00 g of methacryloyloxy-γ-butyrolactone, 2.08 g of 3-hydroxy-1-adamantyl methacrylate, and 0.38 g of azobisisobutyronitrile were dissolved in 80 mL of tetrahydrofuran to obtain a reaction solution. This reaction solution was polymerized for 22 hours under a nitrogen atmosphere at a reaction temperature of 63°C, and then the reaction solution was dropped into 400 mL of n-hexane. The resin thus produced was coagulated and purified, and the resulting white powder was filtered and dried overnight at 40°C under reduced pressure to obtain the compound represented by the following formula (16).

In formula (16), 40, 40, and 20 indicate the ratio of each constituent unit and do not indicate that it is a block copolymer.

Next, the photoresist layer was exposed to light using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix), baked (PEB) at 115°C for 90 seconds, and developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds to obtain a positive resist pattern.

[Comparative Example 6]
A photoresist layer was formed directly on a _SiO2 substrate in the same manner as in Example 31-1, except that no underlayer film was formed, to obtain a positive resist pattern.

[evaluation]
For each of Examples 31-1 to 36-2 and Comparative Example 6, the shapes of the obtained 45 nm L/S (1:1) and 80 nm L/S (1:1) resist patterns were observed using an electron microscope (S-4800) manufactured by Hitachi, Ltd. Regarding the shape of the resist pattern after development, those that had no pattern collapse and good rectangularity were evaluated as good, and those that did not were evaluated as bad. Furthermore, as a result of the observation, the minimum line width that had no pattern collapse and good rectangularity was used as an index of evaluation as resolution. Furthermore, the minimum amount of electron beam energy that could draw a good pattern shape was used as an index of evaluation as sensitivity. The results are shown in Table 6.

As is clear from Table 6, the resist patterns in Examples 31-1 to 36-2 were confirmed to be significantly superior in both resolution and sensitivity compared to Comparative Example 6. In addition, it was confirmed that the resist pattern shape after development was free of pattern collapse and had good rectangularity. Furthermore, the difference in the resist pattern shape after development indicated that the lithography underlayer film forming materials in Examples 31-1 to 36-2 had good adhesion to the resist material.

[Example 37]
The composition for forming an underlayer film for lithography used in Example 19-1 was applied onto a SiO ₂ substrate having a thickness of 300 nm, and baked at 240° C. for 60 seconds and then at 400° C. for 120 seconds to form an underlayer film having a thickness of 90 nm. A silicon-containing intermediate layer material was applied onto this underlayer film, and baked at 200° C. for 60 seconds to form an intermediate layer film having a thickness of 35 nm. Furthermore, the ArF resist solution was applied onto this intermediate layer film, and baked at 130° C. for 60 seconds to form a photoresist layer having a thickness of 150 nm. As the silicon-containing intermediate layer material, a silicon atom-containing polymer described in JP-A-2007-226170 <Synthesis Example 1> was used.

Next, the photoresist layer was exposed to light through a mask using an electron beam lithography system (ELS-7500, 50 keV, manufactured by Elionix), baked at 115°C for 90 seconds (PEB), and developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 60 seconds to obtain a 45 nm L/S (1:1) positive resist pattern.

Thereafter, using RIE-10NR manufactured by Samco International, Inc., the silicon-containing intermediate layer film (SOG) was dry-etched using the obtained resist pattern as a mask, followed by dry-etching of the underlayer film using the obtained silicon-containing intermediate layer film pattern as a mask, and then dry-etching of the _SiO2 film using the obtained underlayer film pattern as a mask.

The etching conditions for each are as follows.
[Etching conditions of resist pattern onto resist intermediate layer film]
Output: 50W
Pressure: 20 Pa
Time: 1 min
Etching gas Ar gas flow rate: _CF4 gas flow rate: _O2 gas flow rate = 50:8:2 (sccm)
[Conditions for Etching Resist Intermediate Film Pattern onto Resist Underlayer Film]
Output: 50W
Pressure: 20 Pa
Time: 2 minutes
Etching gas Ar gas flow rate: _CF4 gas flow rate: _O2 gas flow rate = 50:5:5 (sccm)
[Etching conditions of resist underlayer film pattern onto _SiO2 film]
Output: 50W
Pressure: 20 Pa
Time: 2 minutes
Etching gas Ar gas _flow rate: _C5F12 gas flow rate: _C2F6 gas flow rate: _{O2 gas} flow rate
=50:4:3:1 (sccm)

[evaluation]
The cross section of the pattern of Example 37 obtained as described above (shape of the SiO ₂ film after etching) was observed using an electron microscope (S-4800) manufactured by Hitachi, Ltd. It was confirmed that in the example using the underlayer film of the present invention, the shape of the SiO ₂ film after etching in the multilayer resist processing was rectangular and no defects were observed, which was good.

[Examples 38 to 43, Comparative Example 7]
An optical component forming composition having the same composition as the solution of the underlayer film forming material for lithography prepared in each of the above Examples 19-1 to 24-2 and Comparative Example 5 was applied onto a _SiO2 substrate having a thickness of 300 nm, and baked at 260°C for 300 seconds to form a film for optical components having a thickness of 100 nm. Next, a refractive index and transparency test was performed at a wavelength of 633 nm using a vacuum ultraviolet multi-angle spectroscopic ellipsometer (VUV-VASE) manufactured by J.A. Woollam Japan, and the refractive index and transparency were evaluated according to the following criteria. The evaluation results are shown in Table 7.

[Evaluation criteria for refractive index]
A: Refractive index is 1.65 or more C: Refractive index is less than 1.65

[Transparency evaluation criteria]
A: Extinction coefficient is less than 0.03 C: Extinction coefficient is 0.03 or more

It was found that the optical component forming compositions of Examples 38-1 to 43-2 not only had a high refractive index, but also a low absorption coefficient and excellent transparency. On the other hand, it was found that the composition of Comparative Example 7 had poor performance as an optical component.

[Example 44] Purification of R1-BisA-CN with Acid In a 1000 mL capacity four-neck flask (bottom-opening type), 150 g of a solution (10 mass%) obtained in Synthesis Example 1 dissolved in cyclohexanone was charged and heated to 80 ° C. with stirring. Next, 37.5 g of an aqueous oxalic acid solution (pH 1.3) was added, stirred for 5 minutes, and then allowed to stand for 30 minutes. As a result, the oil phase and the aqueous phase were separated, and the aqueous phase was removed. After repeating this operation once, 37.5 g of ultrapure water was charged into the obtained oil phase, stirred for 5 minutes, and then allowed to stand for 30 minutes, and the aqueous phase was removed. After repeating this operation three times, the flask was heated to 80 ° C. while reducing the pressure in the flask to 200 hPa or less, and the residual water and cyclohexanone were concentrated and distilled off. Thereafter, EL grade cyclohexanone (a reagent manufactured by Kanto Chemical Co., Ltd.) was diluted to adjust the concentration to 10% by mass, thereby obtaining a cyclohexanone solution of R1-BisA-CN with a reduced metal content.

Comparative Example 8 Purification of R1-BisA-CN with Ultrapure Water The same procedure as in Example 44 was carried out except that ultrapure water was used instead of the aqueous oxalic acid solution, and the concentration was adjusted to 10 mass % to obtain a cyclohexanone solution of R1-BisA-CN.

The metal contents of the 10% by mass cyclohexanone solution of R1-BisA-CN before treatment, and the solutions obtained in Example 44 and Comparative Example 8 were measured by ICP-MS. The measurement results are shown in Table 8.

<Example B1-1>
The composition for forming an underlayer film for lithography prepared in Example 19-1 was spin-coated on a silicon substrate and baked at 150° C. for 60 seconds to form a film and remove the solvent. Thereafter, a high-temperature heat resistance evaluation was performed using a lamp annealing furnace as described below.

<Examples B1-2 to B6-2, Comparative Examples B1 to B2>
Except for changing the composition for forming an underlayer film for lithography used to the composition shown in Table 9, the high-temperature heat resistance evaluation was carried out in the same manner as in Example B1-1.

[Evaluation of high temperature heat resistance of cured film]
The substrate on which the film was formed was heated at 450°C in a nitrogen atmosphere, and the film thickness change rate was obtained for 4 minutes and 10 minutes after the start of heating. In addition, heating was continued at 550°C in a nitrogen atmosphere, and the film thickness change rate was obtained for 4 minutes and 10 minutes after the start of heating. These film thickness change rates were evaluated as an index of the heat resistance of the cured film. The film thickness before and after the heat resistance test was measured with an interference film thickness meter, and the film thickness change rate (percentage %) based on the film thickness before the heat resistance test treatment was taken as the film thickness variation value. The results are shown in Table 9. In the table, positive values indicate that the film has shrunk.

<Example C1>
A 12-inch silicon wafer was subjected to a thermal oxidation treatment to prepare a substrate having a silicon oxide film, and a resin film having a thickness of 100 nm was formed thereon in the same manner using the film-forming composition for lithography of Example 19-1. A silicon oxide film and a SiN film were formed on the resin film as described below, and the PE-CVD film formability was evaluated.

<Examples C1-2 to C6-2 and Comparative Examples C1 to C2>
A film was formed in the same manner as in Example C1-1, except that the film-forming composition for lithography used was changed to the composition shown in Table 10, and then evaluation was performed.

[Silicon oxide film evaluation]
A silicon oxide film having a thickness of 70 nm was formed on the resin film using a film forming apparatus TELINDY (manufactured by Tokyo Electron Ltd.) and using TEOS (tetraethylsiloxane) as a raw material at a substrate temperature of 300° C. A defect inspection was performed using a KLA-Tencor SP-5 for the wafer with the cured film on which this silicon oxide film was laminated, and the number of defects in the formed oxide film was evaluated using the number of defects of 21 nm or more as an index.
A Number of defects ≦ 20 B 20 pieces < Number of defects ≦ 50 C 50 pieces < Number of defects ≦ 100 D 100 pieces < Number of defects ≦ 1000 E 1000 pieces < Number of defects ≦ 5000 F 5000 pieces < Number of defects

[SiN film evaluation]
Using the same method as above, a cured film was formed on a substrate having a silicon oxide film of 100 nm thickness formed by thermal oxidation on a 12-inch silicon wafer, and a film forming apparatus TELINDY (manufactured by Tokyo Electron Ltd.) was used to form a SiN film having a thickness of 40 nm, a refractive index of 1.94, and a film stress of -54 MPa at a substrate temperature of 350°C using SiN ₄ (monosilane) and ammonia as raw materials. A defect inspection was performed using a KLA-Tencor SP-5 for the wafer with the cured film laminated thereon, and the number of defects in the formed oxide film was evaluated using the number of defects of 21 nm or more as an index as described above. These results are shown in Table 10.

The silicon oxide films or SiN films formed on the resin films of Examples C1-1 to C6-2 had 50 or less defects measuring 21 nm or more (rating B or higher), which was shown to be less than the number of defects in Comparative Examples C1 or C2.

<Example D1-1>
A 12-inch silicon wafer was subjected to a thermal oxidation treatment to form a silicon oxide film, and a resin film was formed to a thickness of 100 nm on the substrate using the lithography film-forming composition solution obtained in Example 19-1 in the same manner as in Example C1-1. The resin film was further subjected to an annealing treatment by heating at 600°C for 4 minutes using a hot plate capable of high-temperature treatment in a nitrogen atmosphere, to produce a wafer on which an annealed resin film was laminated. The substrate was subjected to an etching evaluation as described below.

[Etching evaluation after high-temperature treatment]
The substrate was etched using a TELIUS etching device (manufactured by Tokyo Electron Co., Ltd.) under conditions of using CF ₄ /Ar and Cl ₂ /Ar as etching gases, and the etching rate was evaluated. The etching rate was evaluated by using a 200 nm thick resin film prepared by annealing SU8 (manufactured by Nippon Kayaku Co., Ltd.) at 250° C. for 1 minute as a reference, and calculating the speed ratio of the etching rate to SU8 as a relative value.

<Examples D1-2 to D6-2, Comparative Examples D1 to D2>
Except for changing the composition for forming a film for lithography used to the composition shown in Table 11, the etching evaluation after the high-temperature treatment was carried out in the same manner as in Example D1-1.

The prepolymer of the present invention has high heat resistance and high solvent solubility, and can be applied to wet processes. Therefore, the lithography film-forming material using the prepolymer of the present invention and the lithography film thereof can be widely and effectively used in various applications requiring these performances. Therefore, the present invention can be widely and effectively used in, for example, electrical insulating materials, resist resins, semiconductor sealing resins, printed wiring board adhesives, electrical laminates mounted on electrical equipment, electronic equipment, industrial equipment, etc., matrix resins for prepregs mounted on electrical equipment, electronic equipment, industrial equipment, etc., build-up laminate materials, resins for fiber reinforced plastics, sealing resins for liquid crystal display panels, paints, various coating agents, adhesives, coating agents for semiconductors, resist resins for semiconductors, resins for forming underlayer films, etc. In particular, the present invention can be effectively used in the field of lithography films.

Claims (16)

A prepolymer having a triazine skeleton obtained by reacting a polyfunctional cyanate compound with a phenol,
The polyfunctional cyanate compound is represented by formula ( 1-1 ) or formula ( 2-1 ),
The phenol is represented by formula (4),
The mass average molecular weight is 5493 to 10000.
Prepolymer for film-forming materials for lithography.
(In formula ( 1-1 ) and formula ( 2-1 ),
^R2 is a single bond or a divalent group having 0 to 40 carbon atoms which may contain a heteroatom;
^R3 is a trivalent group having 0 to 40 carbon atoms which may contain a heteroatom;
R ⁰ each independently represents an alkyl group having 1 to 40 carbon atoms which may have a substituent, an aryl group having 6 to 40 carbon atoms which may have a substituent, an alkenyl group having 2 to 40 carbon atoms which may have a substituent, an alkynyl group having 2 to 40 carbon atoms which may have a substituent, an alkoxy group having 1 to 40 carbon atoms which may have a substituent, or an aryloxy group having 6 to 40 carbon atoms which may have a substituent,
Each m' is independently an integer from 0 to 8 ;
Each p is independently an integer of 0 to 3.
In formula (4), Z is a single bond, a heteroatom, or a divalent hydrocarbon group having 1 to 40 carbon atoms which may contain a heteroatom;
R ¹ 's are each independently an alkyl group having 1 to 40 carbon atoms which may have a substituent, an aryl group having 6 to 40 carbon atoms which may have a substituent, an alkenyl group having 2 to 40 carbon atoms which may have a substituent, an alkoxy group having 1 to 40 carbon atoms which may have a substituent, a halogen atom, or a hydroxyl group, with the proviso that at least one R ¹ is a hydroxyl group;
Each e is independently an integer from 1 to 9;
Each f is independently an integer from 0 to 3;
n is an integer from 0 to 3. The prepolymer according to claim 1 , wherein the phenol represented by the formula (4) is a monophenol represented by the following formula (4-1):
(In formula (4-1), R ¹ , e, and f are defined as above, with the proviso that the number of hydroxyl groups is one.) The prepolymer according to claim 1 or 2 , which has a phenolic hydroxyl group at its terminal. A film-forming composition for lithography, comprising the prepolymer according to any one of claims 1 to 3 . The film-forming composition for lithography according to claim 4 , further comprising a solvent. A resist film formed from the composition according to claim 4 or 5 . forming a resist film on a substrate using the film-forming composition for lithography according to claim 4 or 5 ;
exposing at least a portion of the formed resist film;
developing the exposed resist film to form a resist pattern;
A method for forming a resist pattern comprising the steps of: A film-forming composition for lithography, comprising the prepolymer according to any one of claims 1 to 3 , a diazonaphthoquinone photoactive compound, and a solvent,
The film-forming composition for lithography, wherein the content of the solvent in the composition is 20 to 99 mass %. When the components other than the solvent are considered to be solid contents, the solid contents are
1 to 99% by weight of the prepolymer;
99 to 1% by weight of the diazonaphthoquinone photoactive compound;
The film-forming composition for lithography according to claim 8 , further comprising 0 to 49% by mass of other optional components. 10. An amorphous film obtained by spin coating the film-forming composition for lithography according to claim 4 , 5 , 8 or 9 . A method for producing an amorphous film, comprising the step of forming an amorphous film on a substrate using the film-forming composition for lithography according to claim 4 . A process for forming a resist film on a substrate using the film-forming composition for lithography according to any one of claims 4 , 5 , 8 , and 9 ;
exposing at least a portion of the formed resist film;
developing the exposed resist film to form a resist pattern. An underlayer film for lithography formed from the film-forming composition for lithography according to any one of claims 4 , 5 , 8 and 9 . A method for producing an underlayer film for lithography, comprising the step of forming an underlayer film on a substrate using the film-forming composition for lithography according to claim 4 . A process for forming an underlayer film on a substrate using the film-forming composition for lithography according to any one of claims 4, 5, 8, and 9;
forming at least one photoresist layer on the underlayer film;
irradiating predetermined areas of the photoresist layer with radiation and developing the photoresist layer to form a resist pattern;
The method for forming a resist pattern comprises the steps of: A step of forming an underlayer film on a substrate using the film-forming composition for lithography according to any one of claims 4, 5, 8, and 9;
forming an intermediate layer film on the underlayer film using a resist intermediate layer film material containing silicon atoms;
forming at least one photoresist layer on the intermediate layer film;
irradiating predetermined areas of the photoresist layer with radiation and developing the photoresist layer to form a resist pattern;
a step of etching the intermediate layer film using the resist pattern as a mask to form an intermediate layer film pattern;
forming an underlayer film pattern by etching the underlayer film using the intermediate layer film pattern as an etching mask;
forming a pattern on the substrate by etching the substrate using the underlayer film pattern as an etching mask;
The pattern forming method comprises the steps of: