WO2019044469A1 - Method for forming pattern, resist composition, and method for manufacturing electronic device - Google Patents

Abstract

Provided is a method for forming a pattern with which it is possible to obtain a pattern that excels in rectangularity. Also provided are a resist composition used in the method for forming the pattern, and a method for manufacturing an electronic device. The method for forming the pattern includes the steps of: exposing, using an i ray, a resist film that includes a novolac resin and a photo-acid generator that generates acid by exposure to an i ray, the content of the novolac resin being 50 mass% or greater with respect to the total solid content of the resist film; and developing the resist film using a developer that contains an organic solvent and forming a pattern.

Description

Pattern forming method, resist composition, method of manufacturing electronic device

The present invention relates to a pattern forming method, a resist composition, and a method of manufacturing an electronic device.

From the resist for KrF excimer laser (248 nm), an image forming method called chemical amplification is used as an image forming method of a resist in order to compensate for the decrease in sensitivity due to light absorption. For example, as a method for forming an image of chemical amplification, the following methods may be mentioned.
The resist film is exposed to an excimer laser, an electron beam, extreme ultraviolet light or the like, and the photoacid generator in the resist film is decomposed in the exposed portion to generate an acid. Furthermore, there is a method of using the generated acid as a reaction catalyst to change the solubility of the resist film in the exposed area, and thereafter removing the exposed area or the unexposed area with a developer to form an image.

For example, in Patent Document 1, “a negative resist composition used in the step of exposing using at least two exposure light sources selected from“ g-line, i-line, KrF excimer laser and electron beam, and an alkali-soluble resin A negative resist comprising an acid generator component (B) capable of generating an acid upon irradiation with a component (A), g-line, i-line, KrF excimer laser and electron beam, and a crosslinking agent component (C) A composition (Claim 1) is disclosed.

JP 2006-317584 A

In recent years, miniaturization using the wavelength of the exposure light source is reaching its limit, and in the case of the implantation process application and NAND memory (NOT AND memory), in particular, three-dimensionalization of the memory layer is becoming mainstream for the purpose of increasing the capacity. is there. Since three-dimensionalization of the memory layer requires an increase in the number of processing steps in the longitudinal direction, the resist film is required to be thickened from the conventional nanometer order to the micrometer order.
When such a resist film is thickened, it is required to obtain a pattern having excellent rectangularity in order to realize three-dimensional fine processing.

When the present inventors examined the negative resist composition described in Patent Document 1, they found that there is room to further improve the rectangularity of the obtained pattern.

Then, this invention makes it a subject to provide the pattern formation method which can obtain the pattern which is excellent in rectangularity.
Another object of the present invention is to provide a resist composition used in the above pattern forming method and a method of manufacturing an electronic device.

As a result of intensive studies to achieve the above problems, the present inventors exposed a resist film containing a novolak resin and a predetermined photoacid generator with i-line, and further developed using a developer containing an organic solvent. By forming a pattern, it discovers that the said subject can be solved and completed this invention.
That is, it discovered that the said objective could be achieved by the following structures.

[1] A resist film containing a novolac resin and a photoacid generator that generates an acid upon i-line exposure, wherein the content of the novolac resin is 50% by mass or more based on the total solid content of the resist film Forming a pattern by exposing the resist film using i-line, and developing the resist film with a developer containing an organic solvent to form a pattern.
[2] The method for forming a pattern according to [1], wherein the resist film further contains a crosslinking agent.
[3] The pattern forming method according to [2], wherein the crosslinking agent is a compound having a methoxymethyl group.
[4] The method for forming a pattern according to [3], wherein the compound having a methoxymethyl group has 6 or more methoxymethyl groups.
[5] The pattern forming method according to [3] or [4], wherein the compound having a methoxymethyl group has a phenolic hydroxyl group.
[6] The pattern forming method according to any one of [1] to [5], wherein the novolak resin has an acid dissociable group.
[7] The pattern forming method according to any one of [1] to [6], wherein the film thickness of the resist film is 15 μm or more.
[8] The resist film is formed using a resist composition containing the novolak resin and the photoacid generator.
The pattern forming method according to any one of [1] to [7], wherein a solid content of the resist composition is 40% by mass or more.
[9] The pattern forming method according to any one of [1] to [8], wherein the developer contains an ester solvent having a boiling point of 130 ° C. or less.
[10] The pattern forming method according to any one of [1] to [9], wherein the developer contains butyl acetate.
[11] The pattern forming method according to any one of [1] to [10], wherein the temperature of the developer is from 30 to 60.degree.
[12] The pattern forming method according to any one of [1] to [11], wherein the developer is supplied onto the resist film for a total of 30 seconds or more.
[13] A resist composition for use in the pattern forming method according to any one of [1] to [12], which comprises a novolak resin and a photoacid generator which generates an acid upon i-ray exposure.
[14] A manufacturing method of an electronic device, comprising the pattern forming method according to any one of [1] to [12].

According to the present invention, it is possible to provide a pattern formation method capable of obtaining a pattern excellent in rectangularity.
Further, according to the present invention, it is possible to provide a resist composition used in the above pattern formation method and a method of manufacturing an electronic device.

Hereinafter, the present invention will be described in detail.
Although the description of the configuration requirements described below may be made based on the representative embodiments of the present invention, the present invention is not limited to such embodiments.
In the present specification, “to” is used in the meaning including the numerical values described before and after it as the lower limit value and the upper limit value.
The "i-line" in the present specification means light of wavelength 365 nm.
As used herein, "boiling point" intends a boiling point at 1 atmosphere.

In the present specification, (meth) acrylate represents acrylate and methacrylate.
In the present specification, the weight average molecular weight (Mw), number average molecular weight (Mn) and dispersion degree (also referred to as molecular weight distribution) (Mw / Mn) of a resin are GPC (Gel Permeation Chromatography) devices (HLC- manufactured by Tosoh Corporation) GPC measurement (solvent: tetrahydrofuran, flow rate (sample injection amount): 10 μL, column: TSK gel Multipore HXL-M manufactured by Tosoh Corporation, column temperature: 40 ° C., flow rate: 1.0 mL / min, detector: differential refraction It is defined as a polystyrene conversion value by a refractive index detector (Refractive Index Detector).

With respect to the notation of groups (atomic groups) in the present specification, the notation not describing substitution and non-substitution also includes a group having a substituent as well as a group having no substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group). Also, "organic group" in the present specification means a group containing at least one carbon atom.

Moreover, in the present specification, the type of substituent, the position of the substituent, and the number of substituents in the case of “may have a substituent” are not particularly limited. The number of substituents may be, for example, one or two or more. Examples of the substituent include monovalent nonmetal atomic groups other than hydrogen atom, and can be selected from, for example, the following substituents T.
(Substituent T)
As the substituent T, halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom; alkoxy groups such as methoxy group, ethoxy group and tert-butoxy group; aryloxy such as phenoxy group and p-tolyloxy group Groups; alkoxycarbonyl groups such as methoxycarbonyl group, butoxycarbonyl group, and phenoxycarbonyl group; acyloxy groups such as acetoxy group, propionyloxy group, and benzoyloxy group; acetyl group, benzoyl group, isobutyryl group, acryloyl group, methacryloyl group And an acyl group such as methoxalyl group; an alkylsulfanyl group such as a methylsulfanyl group and a tert-butylsulfanyl group; an arylsulfanyl group such as a phenylsulfanyl group and a p-tolylsulfanyl group; an alkyl group; Aryl, heteroaryl, hydroxy, carboxy, formyl, sulfo, cyano, alkylaminocarbonyl, arylaminocarbonyl, sulfonamide, silyl, amino, monoalkylamino, dialkyl Amino groups; arylamino groups; and combinations thereof.

The feature of the pattern forming method of the present invention is that the content of the novolak resin in the resist film is 50% by mass or more with respect to the total solid content of the resist film, and using a developer containing an organic solvent There is a point that
Although the mechanism which can solve the subject of the present invention by such a pattern formation method is not necessarily clear, the present inventors presume as follows.
First, it is estimated that the heat resistance of the pattern can be improved by using novolac resin. Therefore, it is considered that the deterioration of the pattern shape can be avoided when the heat treatment after development is performed at a stage where the crosslinking is not completed. Further, it is considered that the development with a developer containing an organic solvent also suppresses the deterioration of the resolution.

[Resist film]
First, the resist film used in the pattern formation method of the present invention will be described in detail.

<Novolak resin>
The resist film used in the pattern formation method of the present invention contains a novolac resin. Further, the content of the novolac resin is 50% by mass or more with respect to the total solid content of the resist film.
The novolak resin is described below.

The novolak resin is, for example, a resin obtained by addition condensation of an aromatic compound having a phenolic hydroxyl group (hereinafter, also simply referred to as "phenols") and an aldehyde under an acid catalyst.

Examples of phenols include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol, o-butylphenol, m-butylphenol, p-butylphenol, 5-diethylphenol, 3,5-diethylphenol, 2,3,5-triethylphenol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol 3,5-xylenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, p-phenylphenol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, 2-methoxyphenol, 3-methoxyphenol, 4- Toxiphenol, 2,3-dimethoxyphenol, 2,5-dimethoxyphenol, 3,5-dimethoxyphenol, 2-methoxyresorcinol, phodroquinone, 4-tert-butylcatechol, hydroquinone monomethyl ether, pyrogallol, phlorogricinol, hydroxydiphenyl , Bisphenol A, gallic acid, gallic acid ester, α-naphthol, β-naphthol, 1,3-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, and condensation of xylenol with hydroxybenzaldehyde Polyhydroxy triphenyl methane compounds can be mentioned.
These may be used alone or in combination of two or more.
Among them, as phenols, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,5-xylenol, 3,4-xylenol, 3,5 from the viewpoint that the rectangularity of the pattern is more excellent. -Xylenol, 2,3,5-trimethylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-tert-butyl-4-methylphenol or 2-tert-butyl-5- Methylphenol is preferred, and m-cresol or p-cresol is more preferred.

Examples of aldehydes include aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, acrolein and crotonaldehyde; alicyclic aldehydes such as cyclohexane aldehyde, cyclopentane aldehyde and furylacrolein Furfural, benzaldehyde, o-, m-, and p-methyl benzaldehyde, p-ethyl benzaldehyde, 2,4-, 2,5-, 3,4-, and 3,5-dimethyl benzaldehyde, salicylaldehyde, m -And p-hydroxybenzaldehyde, and aromatic aldehydes such as o-, m- and p-nitrobenzaldehyde; and aromatic oils such as phenylacetaldehyde and cinnamic aldehyde Family aldehydes and the like.
These may be used alone or in combination of two or more.
Among them, formaldehyde is preferable because it is industrially easily available.

The catalyst in addition condensation includes, for example, inorganic acids such as hydrochloric acid, sulfuric acid, perchloric acid and phosphoric acid, organic acids such as formic acid, acetic acid, oxalic acid, trichloroacetic acid and p-toluenesulfonic acid; and zinc acetate and zinc chloride And divalent metal salts such as magnesium acetate.
These may be used alone or in combination of two or more.
The amount of the catalyst used is preferably 0.01 to 1 mol per 1 mol of aldehydes.

The condensation reaction can be carried out according to a conventional method. For example, the reaction may be carried out at a temperature in the range of 60 to 150 ° C. for about 2 to 30 hours. In this reaction, for example, a reaction solvent such as ethyl cellosolve or methyl ethyl ketone may be used. Further, after completion of the reaction, in order to remove the acid catalyst, a basic compound may be added for neutralization, and the neutralized salt may be removed by washing with water.

As the novolak resin, for example, a resin having a repeating unit represented by the following general formula (N) is preferable.

As phenols from which the above novolak resin is derived, it is preferable to use m-cresol and p-cresol in combination. In that case, the compounding ratio (mass ratio) of m-cresol to p-cresol (m-cresol / p-cresol) is preferably 30/70 to 50/50 from the viewpoint that the rectangularity of the pattern is more excellent, 35/65 to 45/55 is more preferable, and 37.5 / 62.5 to 42.5 / 57.5 is more preferable.

In the novolak resin, the weight average molecular weight is preferably 2,000 to 30,000, more preferably 3,000 to 20,000, and still more preferably 3,500 to 17,000.

Moreover, it is preferable to introduce an acid dissociable group into the phenolic hydroxyl group of the above-mentioned novolak resin, and the novolac resin has an acid dissociable group.
In the present specification, derivatives of novolac resins into which an acid dissociable group has been introduced in this way are also included in the novolac resins.

The acid dissociable group introduced into the novolak resin is not particularly limited as long as it is a protective group that can be cleaved by the action of an acid, and examples thereof include groups known as acid dissociable groups. The acid dissociable group is introduced in the form of substitution with the hydrogen atom of the phenolic hydroxyl group in the novolak resin obtained by condensation as described above.

The acid-dissociable group, for _{example, -C (R 36) (R} 37) (R 38), - C (R 36) (R 37) (OR 39), and _{-C (R 01) (R 02} ) (OR ₃₉ ) and the like.
In addition, "-" in the acid-dissociable group exemplified above represents a bond.
In the formula, each of R ₃₆ to R ₃₉ independently represents an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group. R ₃₆ and R ₃₇ may combine with each other to form a ring.
Each of R ₀₁ and R ₀₂ independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group or an alkenyl group.

The alkyl group of R ₃₆ to R ₃₉ , R ₀₁ and R ₀₂ is preferably an alkyl group having a carbon number of 1 to 12, and examples thereof include a methyl group, an ethyl group, a propyl group, an n-butyl group and a sec-butyl group And xyl and octyl groups.
The cycloalkyl group of R ₃₆ to R ₃₉ , R ₀₁ and R ₀₂ may be monocyclic or polycyclic. The monocyclic cycloalkyl group is preferably a cycloalkyl group having a carbon number of 3 to 12, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. The polycyclic cycloalkyl group is preferably a cycloalkyl group having a carbon number of 6 to 20, and examples thereof include an adamantyl group, a norbornyl group, an isobornyl group, a camphanyl group, a dicyclopentyl group, an α-pinel group and a tricyclodecanyl group, Tetracyclododecyl group, and androstanyl group etc. are mentioned. In addition, at least one carbon atom in the cycloalkyl group may be substituted by a hetero atom such as an oxygen atom.
The aryl group of R ₃₆ to R ₃₉ , R ₀₁ and R ₀₂ is preferably an aryl group having a carbon number of 6 to 10, and examples thereof include a phenyl group, a naphthyl group and an anthryl group.
The aralkyl group of R ₃₆ to R ₃₉ , R ₀₁ and R ₀₂ is preferably an aralkyl group having a carbon number of 7 to 12, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group.
The alkenyl group of R ₃₆ to R ₃₉ , R ₀₁ and R ₀₂ is preferably an alkenyl group having a carbon number of 2 to 8, and examples thereof include a vinyl group, an allyl group, a butenyl group, and a cyclohexenyl group.
The ring formed by bonding R ₃₆ and R ₃₇ to each other is preferably a cycloalkyl group (monocyclic or polycyclic). The cycloalkyl group is preferably a monocyclic cycloalkyl group such as a cyclopentyl group and a cyclohexyl group, or a polycyclic cycloalkyl group such as a norbornyl group, a tetracyclodecanyl group, a tetracyclododecanyl group and an adamantyl group. .

Specific examples of the acid dissociable group include tert-butyl group, tert-butoxycarbonyl group, tert-butoxycarbonylmethyl group, butyloxyethyl group, ethoxypropyl group, ethoxybutyl group, tetrahydro-2-pyranyl group, tetrahydro- 2-furyl group, methoxyethyl group, 1-ethoxyethyl group, propyloxyethyl group, cyclohexyloxyethyl group, 1- (2-methylpropoxy) ethyl group, 1- (2-methoxyethoxy) ethyl group, 1- 2-acetoxyethoxy) ethyl group, 1- [2- (1-adamantyloxy) ethoxy] ethyl group, 1- [2- (1-adamantanecarbonyloxy) ethoxy] ethyl group, 3-oxocyclohexyl group, 4-methyl Tetrahydro-2-pyrone-4-yl group, and represented by the following structural formula That group, and the like. In the following structural formula, * represents a bonding position.

Among them, in the novolak resin having an acid dissociable group, it is preferable that the oxygen atom of the phenolic hydroxyl group and the acid dissociable group are combined to form an acetal group or an ester group, and an acetal group is formed Is more preferable.
The acetal group is usually represented by * -O-CH (R _xa ) -O-R _xb .
Here, R _xa and R _xb each independently represent a monovalent saturated hydrocarbon group having 1 to 18 carbon atoms, and * represents the bonding position of the phenol group to the benzene ring.

Examples of the monovalent saturated hydrocarbon group include a linear or branched alkyl group having 1 to 12 carbon atoms, and a cycloalkyl group having 3 to 12 carbon atoms.
Examples of the alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, propyl group, butyl group, tert-butyl group, pentyl group, hexyl group, heptyl group and octyl group.
The cycloalkyl group having 3 to 12 carbon atoms may be either monocyclic or polycyclic. Examples of the monocyclic cycloalkyl group include cycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a decahydronaphthyl group, an adamantyl group, and a norbornyl group.
Among them, as for the acetal group, it is preferable that R _xa is a tert-butyl group and R _xb is a cyclohexyl group.

That is, the novolac resin preferably has a repeating unit represented by the following general formula (NA).

The introduction ratio (protection ratio) of the acid dissociable group is preferably 5 to 80 mol%, more preferably 10 to 60 mol%, and still more preferably 20 to 60 mol% with respect to the total phenolic hydroxyl groups possessed by the novolak resin.
When the protection ratio is 5 mol% (more preferably 10 mol%, more preferably 20 mol%) or more, the solubility of the resist film in an organic solvent in the unexposed area is more excellent.
If the protection rate is 80 mol% (more preferably 60 mol%) or less, the crosslinking reaction by the crosslinking agent proceeds more sufficiently when the crosslinking agent described later is used.
Within this range, the resolution, the residual film ratio, and the heat resistance after pattern formation with the resist composition using this novolak resin become better. The introduction rate of the acid-dissociable group can be calculated from the weight loss corresponding to the group that can be cleaved by the action of an acid, using, for example, a TG-DTA (thermogravimetric differential thermal analysis) apparatus. The TG-DTA measurement is preferably performed at a heating rate of 10 ° C./min.

The method of introduce | transducing an acid dissociative group into the phenolic hydroxyl group of novolak resin is a well-known method.

In the pattern formation method of the present invention, the content of the novolac resin in the resist film is 50% by mass or more with respect to the total solid content of the resist film.
Among them, the content of the novolak resin in the resist film is preferably 50 to 80% by mass, more preferably 55 to 75% by mass, and still more preferably 60 to 70% by mass, with respect to the total solid content of the resist film.
In the present specification, the total solid content of the resist film is intended to mean all other components in the resist film except the solvent which the resist film may contain.
The novolac resin may be used alone or in combination of two or more.

<Photo acid generator>
The resist film used in the pattern formation method of the present invention further contains a photoacid generator (hereinafter, also simply referred to as "photoacid generator") that generates an acid by i-ray exposure.

The photoacid generator preferably has a decomposition rate of 60 mol% or more, more preferably 80 mol% or more, when it is exposed to i-line at 1000 mJ / cm ² .
The decomposition rate of the photoacid generator can be determined by the following method.
First, a photoacid generator to be measured, and a novolak resin (m-cresol / p-cresol = 50/50, weight average molecular weight: 3000) represented by the above general formula (N), which is a matrix, 1 A resist film containing a ratio of 99/99 (photoacid generator / matrix (mass ratio)) is formed in a film thickness of 30 μm on a silicon wafer (thickness: 725 μm). The silicon wafer is heated at 100 ° C. for 120 seconds, and then exposed to i-line at 1000 mJ / cm ² and heated at 130 ° C. for 60 seconds. Thereafter, the silicon wafer is immersed for 10 minutes while applying ultrasonic waves to a methanol / THF (tetrahydrofuran) = 50/50 solution (mass ratio). The extract is analyzed using HPLC (high performance liquid chromatography), and the obtained result is applied to the following equation to determine the decomposition rate of the photoacid generator.
Decomposition rate (%) = amount of generated acid (mol) / (amount of generated acid (mol) + amount of photo acid generator (mol)) × 100

The photoacid generator preferably has a molar absorption coefficient of 100 to 10000 L / (mol · cm) for i-line, and more preferably 500 to 9000 L / (mol · cm) for i-line. More preferably, the molar absorption coefficient to the i-line is 1000 to 8000 L / (mol · cm).
If the molar absorptivity of the photoacid generator to i-line is 100 L / (mol · cm) or more, the photoacid generator exhibits good photofunctionality to i-line, and 10000 L / (mol · cm) If it is the following, even if it is a thick resist film, the amount of acid generation in the deep part can be secured.
The molar absorption coefficient of the photoacid generator can be measured by a known method. Specifically, for example, it is preferable to use an ethyl acetate solvent and measure at a concentration of 0.01 g / L with an ultraviolet-visible spectrophotometer (Carry-5 spctrophotometer manufactured by Varian).

The photoacid generator preferably generates an acid with a pKa of 0 or less, more preferably an acid with a pKa of -2 or less, and an acid with a pKa of -4 or less, by irradiation with i-line Is more preferred.

Examples of photoacid generators include trichloromethyl-s-triazines, sulfonium salts (such as triarylsulfonium salts), iodonium salts (such as diaryl iodonium salts), quaternary ammonium salts, diazomethane compounds (such as diazomethane derivatives), oximes Sulfonate compounds, and imidosulfonate compounds are included.
Among them, the photoacid generator is preferably a sulfonium salt, more preferably a triarylsulfonium salt.
Specific examples of trichloromethyl-s-triazines, diaryliodonium salts, quaternary ammonium salts, and diazomethane derivatives are described in paragraphs <0083> to <0084>, and <0086> to <2006 of JP-A-2011-221494. The compounds described in the above can be exemplified.

(Triarylsulfonium salt)
Among the triarylsulfonium salts, triarylsulfonium salts represented by the following general formula (S) are preferable.

In general formula (S), R ¹ to R ⁴ each independently represent an alkyl group, a hydroxyl group, an alkoxy group, an alkylcarbonyl group, an arylcarbonyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an arylthiocarbonyl group, an acyloxy group , Arylthio group, alkylthio group, aryl group, heterocyclic hydrocarbon group, aryloxy group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, hydroxy (poly) alkyleneoxy group, hydrogen atom is substituted And an optionally substituted amino group, a cyano group, a nitro group or a halogen atom.

m1, m3 and m4 each independently represent an integer of 0 to 5; Among them, m1, m3 and m4 are each independently preferably 0 to 3, more preferably 0 to 2, still more preferably 0 to 1, and particularly preferably 0.
m2 represents an integer of 0 to 4; Among them, m2 is preferably 0 to 3, more preferably 0 to 2, still more preferably 0 to 1, and particularly preferably 0.

X ^- represents a monovalent polyatomic anion. Among them, X ^- is an anion corresponding to the acid (HX) generated by exposure to the triarylsulfonium salt represented by the general formula (S) with an i-line.
X ^- it is but there is no limit other than that it is a monovalent polyatomic anion, for _{^{example, PY a -, (Rf)}} b PF 6-b -, R 5 c GaY 4-c -, R 6 SO _{^{3 -, (R 6 SO 2}} ) 3 C -, and _{^{(R 6 SO 2) 2 N}} - anion represented by like.

Y represents a halogen atom (preferably a fluorine atom).
R f represents an alkyl group (preferably an alkyl group having 1 to 8 carbon atoms) in which 80 mol% or more of hydrogen atoms are substituted with a fluorine atom.

Further, X ^- is preferably a sulfur atom or a phosphorus atom.

Specific examples of the triarylsulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium trifluoroacetate, 4-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methoxyphenyldiphenylsulfonium trifluoroacetate, 4-phenylthio There may be mentioned phenyl diphenyl sulfonium trifluoromethane sulfonate and 4-phenyl thiophenyl diphenyl sulfonium trifluoroacetate.

(Oxime sulfonate compound)
As a photoacid generator, an oxime sulfonate compound is also preferable.
The oxime sulfonate compound, that is, the compound having an oxime sulfonate group is preferably a compound having an oxime sulfonate group represented by the following general formula (B1).

In formula (B1), R ²¹ represents an alkyl group or an aryl group. A wavy line represents a bond to another group.

As the alkyl group for R ^21, a linear or branched alkyl group having 1 to 10 carbon atoms is preferable. The alkyl group of R ²¹ is an aryl group having 6 to 11 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or a bridged oil such as a cycloalkyl group (7, 7-dimethyl-2-oxo norbornyl group It may be substituted with a ring group, preferably a bicycloalkyl group and the like.
The aryl group of R ²¹ is preferably an aryl group having 6 to 11 carbon atoms, and more preferably a phenyl group or a naphthyl group. The aryl group of R ²¹ may be substituted by a lower alkyl group, an alkoxy group or a halogen atom.

The above-mentioned compound containing an oxime sulfonate group represented by the above general formula (B1) is also preferably an oxime sulfonate compound represented by the following general formula (B2).

In formula (B2), R ⁴² represents an alkyl group or an aryl group, X represents an alkyl group, an alkoxy group or a halogen atom, m 4 represents an integer of 0 to 3, and m 4 is 2 or 3 At certain times, multiple X's may be the same or different.

The alkyl group of X is preferably a linear or branched alkyl group having 1 to 4 carbon atoms. The alkoxy group of X is preferably a linear or branched alkoxy group having 1 to 4 carbon atoms.
The halogen atom of X is preferably a chlorine atom or a fluorine atom.
m4 is preferably 0 or 1. Among them, in the general formula (B2), m4 is 1, X is a methyl group, the substitution position of X is an ortho position, and R ⁴² is a linear alkyl group having 1 to 10 carbon atoms, Compounds which are 7-dimethyl-2-oxonorbornylmethyl or p-toluyl are preferred.

The oxime sulfonate compound represented by the above general formula (B1) is also preferably an oxime sulfonate compound represented by the following general formula (B3).

In formula (B3), R ⁴³ has the same meaning as R ⁴² in formula (B2), and X ¹ is a halogen atom, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, cyano Represents a group or a nitro group, and n4 represents an integer of 0 to 5;

As R ⁴³ , methyl group, ethyl group, n-propyl group, n-butyl group, n-octyl group, trifluoromethyl group, pentafluoroethyl group, perfluoro-n-propyl group, perfluoro-n-butyl group Group, p-tolyl group, 4-chlorophenyl group or pentafluorophenyl group is preferable, and n-octyl group is more preferable.
As X ¹ , an alkoxy group having 1 to 5 carbon atoms is preferable, and a methoxy group is more preferable.
As n4, 0 to 2 is preferable, and 0 to 1 is more preferable.

Specific examples of the compound represented by the above general formula (B3) include α- (methylsulfonyloxyimino) benzyl cyanide, α- (ethylsulfonyloxyimino) benzyl cyanide, α- (n-propylsulfonyloxyimino) ) Benzyl cyanide, α- (n-butylsulfonyloxyimino) benzyl cyanide, α- (4-toluenesulfonyloxyimino) benzyl cyanide, α-[(methylsulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(ethylsulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(n-propylsulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(n-butylsulfonyloxyimino) -4- 4 Methoxyphenyl] acetonitrile, and α- [ 4-toluenesulfonyl) -4-methoxyphenyl] include acetonitrile.

As specific examples of the oxime sulfonate compound, the following compounds (i) to (viii) and the like are also preferable.

The oxime sulfonate compound represented by the above general formula (B1) is also preferably a compound represented by the following general formula (3).

In formula (3), R ¹ represents an alkyl group or an aryl group, and R ² represents an alkyl group, an aryl group or a heteroaryl group. R ³ to R ⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group or a halogen atom. However, R ³ and R ⁴ , R ⁴ and R ⁵ , or R ⁵ and R ⁶ may be respectively bonded to form an alicyclic or aromatic ring. X represents an ether group or a thioether group.

R ¹ represents an alkyl group or an aryl group. The alkyl group is preferably a branched alkyl group or a cyclic alkyl group. The carbon number of the alkyl group is preferably 3 to 10. In particular, when the alkyl group is branched, it preferably has 3 to 6 carbon atoms, and when the alkyl group is cyclic, it preferably has 5 to 7 carbon atoms. As an alkyl group, for example, propyl group, isopropyl group, n-butyl group, s-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, 1,1-dimethylpropyl group, hexyl group And 2-ethylhexyl group, cyclohexyl group, cyclopentyl group and octyl group, and isopropyl group, tert-butyl group, neopentyl group or cyclohexyl group is preferable. The carbon number of the aryl group is preferably 6 to 12, more preferably 6 to 8, and still more preferably 6 to 7. As said aryl group, a phenyl group and a naphthyl group are mentioned, for example, A phenyl group is preferable.
The alkyl group and aryl group of R ¹ may have a substituent. As a substituent, for example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc.), a linear, branched or cyclic alkyl group (a methyl group, an ethyl group, a propyl group etc.), an alkenyl Group, alkynyl group, aryl group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, cyano group, carboxyl group, hydroxyl group, alkoxy group, aryloxy group, alkylthio group, arylthio group, heterocyclic oxy group, acyloxy group Groups, amino groups, nitro groups, hydrazino groups, and heterocyclic groups. Moreover, these groups may be further substituted by a substituent.
As a substituent, a halogen atom or a methyl group is preferable.

R ¹ is preferably, for example, an alkyl group. From the viewpoint of achieving both storage stability and sensitivity, R ¹ is preferably a branched alkyl group having 3 to 6 carbon atoms, a cyclic alkyl group having 5 to 7 carbon atoms, or a phenyl group, and has 3 carbon atoms. A branched alkyl group of to 6 or a cyclic alkyl group having 5 to 7 carbon atoms is more preferable. In addition, when R ¹ is such a bulky group (particularly, a bulky alkyl group), the transparency can be improved.
Among bulky substituents, isopropyl group, tert-butyl group, neopentyl group or cyclohexyl group is preferable, and tert-butyl group or cyclohexyl group is more preferable.

R ² represents an alkyl group, an aryl group or a heteroaryl group. The alkyl group represented by R ² is preferably a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group and cyclohexyl group, with methyl group being preferred. .
The aryl group is preferably an aryl group having 6 to 10 carbon atoms. Examples of the aryl group include a phenyl group, a naphthyl group and a p-toluyl group (p-methylphenyl group), and a phenyl group or a p-toluyl group is preferable. As a heteroaryl group, a pyrrole group, an indole group, a carbazole group, a furan group, and a thiophene group are mentioned, for example.
The alkyl group, aryl group and heteroaryl group represented by R ² may have a substituent. Examples of the substituent include similar substituents alkyl group represented by R ¹ may have.
R ² is preferably an alkyl group or an aryl group, more preferably an aryl group, and still more preferably a phenyl group. As a substituent of a phenyl group, a methyl group is preferable.

Each of R ³ to R ⁶ independently represents a hydrogen atom, an alkyl group, an aryl group or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.). The alkyl group represented by R ³ to R ⁶ has the same meaning as the alkyl group represented by R ² , and the preferred range is also the same. The aryl group represented by R ³ to R ⁶ has the same meaning as the aryl group represented by R ¹ , and the preferred range is also the same.
Among R ³ to R ⁶ , R ³ and R ⁴ , R ⁴ and R ⁵ , or R ⁵ and R ⁶ may combine to form a ring, and as the ring, an alicyclic or aromatic ring is Preferably, a benzene ring is more preferred.
R ³ to R ⁶ are preferably each independently a hydrogen atom, an alkyl group or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom etc.), and a hydrogen atom, a methyl group, a fluorine atom, a chlorine atom or a bromine atom More preferably, it is an atom.
It is also preferable that R ³ and R ⁴ , R ⁴ and R ⁵ , or R ⁵ and R ⁶ combine to form a benzene ring.
More specific preferable embodiments of R ³ to R ⁶ are as follows.
(Aspect 1) At least one (more preferably two or more) is a hydrogen atom.
(Aspect 2) The total number of alkyl groups, aryl groups, and halogen atoms is 3 or less (more preferably 1 or less).
(Aspect 3) R ³ and R ⁴ , R ⁴ and R ⁵ , or R ⁵ and R ⁶ combine to form a benzene ring.
(Aspect 4) An aspect satisfying Aspects 1 and 2 and / or an aspect satisfying Aspects 1 and 3.

X represents an ether group or a thioether group.

The following compounds are illustrated as a specific example of said General formula (3). In the exemplified compounds, Ts represents a tosyl group (p-toluenesulfonyl group), Me represents a methyl group, Bu represents an n-butyl group, and Ph represents a phenyl group.

(Imidosulfonate Compound)
An imidosulfonate compound is also preferable as the photoacid generator.
As an imidosulfonate group which an imidosulfonate compound has, a 5-membered ring imidosulfonate group is preferable. The imidosulfonate compound is preferably a compound represented by the following general formula (3).

In the general formula (3), R ⁶ represents a fluoroalkyl group having 2 or 3 carbon atoms, preferably a perfluoroalkyl group having 2 or 3 carbon atoms.

R ⁷ represents an alkylene group, an alkenylene group or an arylene group. The alkylene group may be linear, branched or cyclic, preferably cyclic. The carbon number of the alkylene group is preferably 1 to 12, more preferably 3 to 12, and still more preferably 3 to 8.
The alkenylene group may be linear, branched or cyclic, preferably cyclic. The carbon number of the alkenylene group is preferably 2 to 12, more preferably 3 to 12, and still more preferably 3 to 8.
The carbon number of the arylene group is preferably 6 to 18, and more preferably 6 to 12.
The imidosulfonate compound is preferably a compound having a 5-membered ring imidosulfonate group and a norbornene group.

Commercially available compounds having an imidosulfonate group include NT-1TF and NT-3TF (manufactured by San-Apro).
Specific examples of the compound having another imidosulfonate group include the following exemplified compounds.

The content of the photoacid generator is preferably 0.1 to 3.0% by mass, more preferably 0.125 to 1.5% by mass, and more preferably 0.15 to 1% with respect to the total solid content of the resist film. 0 mass% is more preferable.
A photo-acid generator may be used individually by 1 type, and may use 2 or more types together.

<Crosslinking agent>
The resist film used in the pattern formation method of the present invention preferably further contains a crosslinking agent.

The crosslinking agent is a compound having a crosslinkable group. The crosslinkable group is preferably capable of reacting with the above-mentioned novolak resin under an acid catalyst to form a crosslinked structure. The crosslinkable group is preferably a hydroxymethyl group or an alkoxymethyl group, more preferably an alkoxymethyl group, still more preferably a methoxymethyl group or an ethoxymethyl group, and particularly preferably a methoxymethyl group, from the viewpoint that the rectangularity of the pattern is more excellent.
The crosslinker preferably has two or more crosslinkable groups in the molecule, more preferably four or more, and preferably six or more.
That is, the crosslinking agent preferably has two or more methoxymethyl groups in the molecule, more preferably four or more, and still more preferably six or more.
The upper limit of the number of crosslinkable groups (preferably methoxymethyl groups) that the crosslinker has in the molecule is not particularly limited, but 10 or less is common.

The crosslinking agent preferably has a phenolic hydroxyl group in the molecule from the viewpoint that the rectangularity of the pattern is more excellent, and preferably has 1 to 4 phenolic hydroxyl groups in the molecule, and has 2 to 3 phenolic hydroxyl groups. Is more preferable, and having three is more preferable.

As the crosslinking agent, a hydroxymethylated or alkoxymethylated phenol compound, an alkoxymethylated melamine compound, an alkoxymethyl glycoluril compound, or an alkoxymethylated urea compound is preferable from the viewpoint that the rectangularity of the pattern is more excellent. Hydroxymethylated or alkoxymethylated phenolic compounds are more preferred, and alkoxymethylated phenolic compounds are even more preferred.

Among them, as a preferable crosslinking agent, the molecule has 2 to 5 benzene rings in the molecule, and additionally 2 or more (preferably, a hydroxymethyl group or an alkoxymethyl group (preferably an alkoxymethyl group, more preferably a methoxymethyl group) (6 or more), and the phenol derivative whose molecular weight is 1200 or less is mentioned.

Among the above crosslinking agents, phenol derivatives having a hydroxymethyl group are obtained by reacting a phenol compound having no corresponding hydroxymethyl group with formaldehyde under a base catalyst. Further, a phenol derivative having an alkoxymethyl group can be obtained by reacting the corresponding phenol derivative having a hydroxymethyl group with an alcohol under an acid catalyst.
Among the phenol derivatives synthesized in this manner, phenol derivatives having an alkoxymethyl group are preferred from the viewpoint of sensitivity and storage stability.

Examples of other preferred crosslinking agents further include compounds having N-hydroxymethyl group or N-alkoxymethyl group such as alkoxymethylated melamine compounds, alkoxymethylglycoluril compounds and alkoxymethylated urea compounds. Be

As such a compound, hexamethoxymethylmelamine, hexaethoxymethylmelamine, tetramethoxymethylglycoluril, 1,3-bismethoxymethyl-4,5-bismethoxyethyleneurea, bismethoxymethylurea and the like can be mentioned. Specific examples of such compounds are disclosed in EP 0,133,216 A, West German Patents 3,634,671, 3,711,264, and EP 0,212,482A.

Examples of preferable crosslinking agents are shown below.

In the structural formulae, each of L ₁ to L ₈ independently represents a hydrogen atom, a hydroxymethyl group, a methoxymethyl group, an ethoxymethyl group, or an alkyl group having 1 to 6 carbon atoms.
Among them, L ₁ to L ₈ are preferably each independently a methoxymethyl group.

The content of the crosslinking agent is preferably 10 to 45% by mass, more preferably 20 to 40% by mass, and still more preferably 30 to 37.5% by mass, with respect to the total solid content of the resist film.

The crosslinking agent may be used singly or in combination of two or more.

<Acid diffusion control agent>
The resist film used in the pattern formation method of the present invention preferably further contains an acid diffusion control agent. The acid diffusion control agent traps an acid generated from a photoacid generator or the like at the time of exposure, and acts as a quencher which suppresses a reaction in an unexposed area by an extra generated acid. For example, a basic compound (DA), a basic compound (DB) whose basicity decreases or disappears upon exposure, an onium salt (DC) that becomes a relatively weak acid to an acid generator, a nitrogen atom, an acid A low molecular weight compound (DD) having a group capable of leaving by the action of or an onium salt compound (DE) having a nitrogen atom in the cation part can be used as an acid diffusion control agent. In the composition of the present invention, known acid diffusion control agents can be suitably used. For example, paragraphs <0627> to <0664> of U.S. Patent Application Publication 2016/0070167 A1; paragraphs <0095> to <0187> of U.S. Patent Application Publication 2015/0004544 A1, U.S. Patent Application Publication 2016/0237190 A1 Known compounds disclosed in paragraphs <0403> to <0423> of the specification and paragraphs <0259> to <0328> of US Patent Application Publication No. 2016/0274458 A1 can be suitably used as an acid diffusion control agent. .

As the basic compound (DA), compounds having the structures represented by the following formulas (A) to (E) are preferable.

In the general formulas (A) and (E),
R ²⁰⁰ , R ²⁰¹ and R ^{202, which} may be the same or different, each independently represent a hydrogen atom, an alkyl group (preferably having a carbon number of 1 to 20), or a hydroxyalkyl group (preferably having a carbon number of 1 to 20, more preferably Represents a carbon number of 2), a cycloalkyl group (preferably having a carbon number of 3 to 20) or an aryl group (having a carbon number of 6 to 20). R ²⁰¹ and R ²⁰² may bond to each other to form a ring.
R ²⁰³ , R ²⁰⁴ , R ²⁰⁵ and R ^{206, which} may be the same or different, each independently represent an alkyl group having 1 to 20 carbon atoms.

The alkyl group in the general formulas (A) and (E) may have a substituent or may not be substituted.
As the alkyl group having a substituent, as the alkyl group having a substituent, an aminoalkyl group having 1 to 20 carbon atoms, a hydroxyalkyl group having 1 to 20 carbon atoms, or a cyanoalkyl group having 1 to 20 carbon atoms is preferable.
The alkyl group in the general formulas (A) and (E) is more preferably unsubstituted.

The basic compound (DA) is preferably guanidine, aminopyrrolidine, pyrazole, pyrazoline, piperazine, aminomorpholine, aminoalkylmorpholine, piperidine or the like, and has an imidazole structure, a diazabicyclo structure, an onium hydroxide structure, an onium carboxylate structure, Compounds having a trialkylamine structure, an aniline structure or a pyridine structure, alkylamine derivatives having a hydroxyl group and / or an ether bond, or aniline derivatives having a hydroxyl group and / or an ether bond are more preferable.

A basic compound (DB) (hereinafter also referred to as a “compound (DB)”) whose basicity is reduced or eliminated by exposure to light has a proton acceptor functional group, and is decomposed by exposure to protonic acid. It is a compound in which the receptor property decreases, disappears, or changes from proton acceptor property to acidity.

The proton acceptor functional group is a functional group having a group or an electron that can electrostatically interact with a proton, and is, for example, a functional group having a macrocyclic structure such as cyclic polyether or π conjugated Means a functional group having a nitrogen atom having a non-covalent electron pair that does not contribute to The nitrogen atom having a noncovalent electron pair not contributing to the π conjugation is, for example, a nitrogen atom having a partial structure shown in the following formula.

Examples of preferable partial structures of the proton acceptor functional group include a crown ether structure, an azacrown ether structure, a primary to tertiary amine structure, a pyridine structure, an imidazole structure, and a pyrazine structure.

The compound (DB) decomposes upon exposure to reduce or eliminate the proton acceptor property, or generates a compound which has changed from the proton acceptor property to the acidity. Here, the reduction or disappearance of the proton acceptor property or the change from the proton acceptor property to the acidity is a change in the proton acceptor property caused by the addition of a proton to the proton acceptor functional group, and is specifically described Means that when a proton adduct is formed from a compound (DB) having a proton acceptor functional group and a proton, the equilibrium constant in its chemical equilibrium decreases.
The proton acceptor property can be confirmed by performing pH measurement.

The acid dissociation constant pKa of the compound generated by decomposition of the compound (DB) upon exposure is preferably pKa <-1, more preferably -13 <pKa <-1, and more preferably -13 <pKa <- It is more preferable to satisfy 3.

The acid dissociation constant pKa represents the acid dissociation constant pKa in an aqueous solution, and is defined, for example, in Chemical Handbook (II) (revised 4th edition, 1993, edited by The Chemical Society of Japan, Maruzen Co., Ltd.). The lower the value of the acid dissociation constant pKa, the greater the acid strength. Specifically, the acid dissociation constant pKa in an aqueous solution can be measured by measuring the acid dissociation constant at 25 ° C. using an infinite dilution aqueous solution. Alternatively, a value based on Hammett's substituent constant and a database of known literature values can be obtained by calculation using software package 1 described below. All the pKa values described in the present specification indicate values calculated by using this software package.

Software Package 1: Advanced Chemistry Development (ACD / Labs) Software V 8.14 for Solaris (1994-2007 ACD / Labs).

In the composition of the present invention, an onium salt (DC) that is relatively weak to the photoacid generator can be used as an acid diffusion control agent.
When a photoacid generator and an onium salt that generates an acid that is a relatively weak acid with respect to the acid generated from the photoacid generator are mixed and used, the acid generated from the photoacid generator upon exposure is not obtained. Upon collision with an onium salt having a weak acid anion for reaction, salt exchange releases a weak acid to form an onium salt having a strong acid anion. In this process, since the strong acid is exchanged to a weak acid having a lower catalytic ability, the acid is apparently inactivated to control the acid diffusion.

As the onium salt which is relatively weak with respect to the photoacid generator, compounds represented by the following general formulas (d1-1) to (d1-3) are preferable.

In the formula, R ⁵¹ is a hydrocarbon group which may have a substituent, and Z ^2c is a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent (but carbon adjacent to S) Fluorine atom is not substituted), R ⁵² is an organic group, Y ³ is a linear, branched or cyclic alkylene group or arylene group, and R f is a fluorine atom And M ⁺ independently represents an ammonium cation, a sulfonium cation, or an iodonium cation.

A compound having a cation site and an anion site in the same molecule and a cation site and an anion site linked by a covalent bond (the onium salt (DC) to be a relatively weak acid with respect to the photoacid generator Hereinafter, it may be referred to as “compound (DCA)”.
The compound (DCA) is preferably a compound represented by any one of the following formulas (C-1) to (C-3).

In the general formulas (C-1) to (C-3),
R ₁ , R ₂ and R ₃ each independently represent a substituent having 1 or more carbon atoms.
L ₁ represents a divalent linking group or a single bond linking a cation site and an anion site.
-X ^- it _^is, -COO ^{-, -SO} 3 - represents an anion portion selected from -R ₄ ^-, -SO ₂ -, and ^-N. R ₄ represents a carbonyl group (—C (= O) —), a sulfonyl group (—S (= O) ₂ —), or a sulfinyl group (—S (= O) — at the linking site to the adjacent N atom And R 1 represents a monovalent substituent having at least one of them.
R ₁ , R ₂ , R ₃ , R ₄ and L ₁ may combine with each other to form a ring. In General Formula (C-3), two of R ₁ to R ₃ may be combined to represent one divalent substituent, which may be bonded to an N atom by a double bond.

As a substituent having 1 or more carbon atoms in R ₁ to R ₃ , an alkyl group, a cycloalkyl group, an aryl group, an alkyloxycarbonyl group, a cycloalkyloxycarbonyl group, an aryloxycarbonyl group, an alkylaminocarbonyl group, a cycloalkylamino group A carbonyl group, and an arylamino carbonyl group etc. are mentioned. Among them, an alkyl group, a cycloalkyl group or an aryl group is preferable.

L ₁ as a divalent linking group is a linear or branched alkylene group, a cycloalkylene group, an arylene group, a carbonyl group, an ether group, an ester group, an amide group, a urethane group, a urea group, or two of them Examples thereof include groups formed by combining species or more. L ₁ is preferably an alkylene group, an arylene group, an ether group, an ester group, or a group formed by combining two or more of these.

The low molecular weight compound (DD) having a nitrogen atom and having a group capable of leaving by the action of an acid (hereinafter also referred to as “compound (DD)”) has a group leaving by the action of an acid on the nitrogen atom It is preferable that it is an amine derivative which it has.
As a group leaving by the action of an acid, an acetal group, a carbonate group, a carbamate group, a tertiary ester group, a tertiary hydroxyl group, or a hemiaminal ether group is preferable, and a carbamate group or a hemiaminal ether group is more preferable. .
The molecular weight of the compound (DD) is preferably 100 to 1000, more preferably 100 to 700, and still more preferably 100 to 500.
The compound (DD) may have a carbamate group having a protecting group on the nitrogen atom. The protective group constituting the carbamate group is represented by the following general formula (d-1).

In the general formula (d-1),
Each Rb independently represents a hydrogen atom, an alkyl group (preferably 1 to 10 carbon atoms), a cycloalkyl group (preferably 3 to 30 carbon atoms), an aryl group (preferably 3 to 30 carbon atoms), an aralkyl group (preferably Preferably, it represents 1 to 10 carbon atoms, or an alkoxyalkyl group (preferably 1 to 10 carbon atoms). Rb may be mutually bonded to form a ring.
The alkyl group, the cycloalkyl group, the aryl group and the aralkyl group represented by R b are each independently a hydroxyl group, a cyano group, an amino group, a pyrrolidino group, a piperidino group, a morpholino group, an oxo group and the like, an alkoxy group or a halogen It may be substituted by an atom. The same applies to the alkoxyalkyl group represented by Rb.

As R b, a linear or branched alkyl group, a cycloalkyl group or an aryl group is preferable, and a linear or branched alkyl group or a cycloalkyl group is more preferable.
Alicyclic hydrocarbon, aromatic hydrocarbon, heterocyclic hydrocarbon, its derivative etc. are mentioned as a ring which two Rb couple | bonds mutually, and forms.
Specific examples of the structure of the group represented by Formula (d-1) include, but are not limited to, the structures disclosed in paragraph <0466> of US Patent Publication No. US 2012/0135348 A1.

The compound (DD) preferably has a structure represented by the following general formula (6).

In the general formula (6),
l represents an integer of 0 to 2, m represents an integer of 1 to 3, and l + m = 3 is satisfied.
Ra represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. When l is 2, two Ras may be the same or different, and two Ras may be bonded to each other to form a heterocyclic ring with the nitrogen atom in the formula. The hetero ring may contain a hetero atom other than the nitrogen atom in the formula.
Rb has the same meaning as Rb in formula (d-1), and the preferred examples are also the same.
In the general formula (6), the alkyl group, cycloalkyl group, aryl group and aralkyl group as Ra are each independently substituted with an alkyl group, cycloalkyl group, aryl group and aralkyl group as Rb. It may be substituted by the same group as the group described above as a preferable group.

Specific examples of the alkyl group, cycloalkyl group, aryl group, and aralkyl group (these groups may be substituted with the above group) of the above Ra include the same groups as the specific examples described above for Rb. Be
Specific examples of particularly preferred compound (DD) in the present invention include, but are not limited to, the compounds disclosed in paragraph <0475> of US Patent Application Publication 2012/0135348 A1.

The onium salt compound (DE) having a nitrogen atom in the cation part (hereinafter, also referred to as a "compound (DE)") is preferably a compound having a basic site containing a nitrogen atom in the cation part. The basic moiety is preferably an amino group, more preferably an aliphatic amino group. It is further preferred that all of the atoms adjacent to the nitrogen atom in the basic site are hydrogen atoms or carbon atoms. Further, from the viewpoint of improving basicity, it is preferable that an electron-withdrawing functional group (such as a carbonyl group, a sulfonyl group, a cyano group, and a halogen atom) is not directly linked to the nitrogen atom.
Preferred specific examples of the compound (DE) include, but are not limited to, the compounds disclosed in paragraph <0203> of US Patent Application Publication No. 2015/0309408 A1.

Preferred examples of the acid diffusion control agent are shown below.

The acid diffusion control agent may be used singly or in combination of two or more.
The content of the acid diffusion controlling agent (the total amount of the acid diffusion controlling agent, if any) is preferably 0.05 to 10% by mass, and more preferably 0.05 to 5% by mass with respect to the total solid content of the resist film.

<Surfactant>
When the resist film used in the pattern formation method of the present invention contains a surfactant preferably containing a surfactant, the fluorine-based and / or silicon-based surfactant (specifically, a fluorine-based surfactant) , Silicon-based surfactants, or surfactants having both fluorine atoms and silicon atoms) are preferred.

When the resist film contains a surfactant, a pattern with less adhesion and development defects can be obtained with good sensitivity and resolution.
As the fluorine-based and / or silicon-based surfactant, the surfactants described in paragraph <0276> of US Patent Application Publication No. 2008/0248425 can be mentioned.
In addition, other surfactants than the fluorine-based and / or silicon-based surfactants described in paragraph <0280> of US Patent Application Publication No. 2008/0248425 can also be used.

These surfactants may be used alone or in combination of two or more.
When the composition of the present invention contains a surfactant, the content of the surfactant is preferably 0.0001 to 2% by mass, more preferably 0.0005 to 1% by mass, with respect to the total solid content of the resist film. preferable.

(Other additives)
The resist film used in the pattern formation method of the present invention further comprises a resin other than novolak resin, an acid multiplying agent, a dye, a plasticizer, a photosensitizer, a light absorber, a dissolution inhibitor, or a dissolution accelerator, etc. May be included.

[Resist composition]
The resist film is preferably formed using a resist composition obtained by dispersing the above-described components in a solvent.
The resist composition preferably comprises at least a novolak resin and a photoacid generator which generates an acid upon i-line exposure.
The solvent used for preparation of a resist composition is demonstrated below.

<Solvent>
In the resist composition used by the pattern formation method of this invention, a well-known solvent can be used suitably. For example, paragraphs <0665> to <0670> of U.S. Patent Application Publication 2016 / 0070167A1; paragraphs <0210> to <0235> of U.S. Patent Application Publication 2015 / 0004544A1, U.S. Patent Application Publication 2016 / 0237190A1 Known solvents disclosed in paragraphs <0424> to <0426> of the specification and paragraphs <0357> to <0366> of US Patent Application Publication 2016/0274458 A1 can be suitably used.
Examples of solvents that can be used when preparing the composition include, for example, alkylene glycol monoalkyl ether carboxylate, alkylene glycol monoalkyl ether, lactic acid alkyl ester, alkyl alkoxypropionate, cyclic lactone (preferably having a carbon number of 4 to 10), Examples thereof include organic solvents such as a monoketone compound (preferably having a carbon number of 4 to 10) which may have a ring, an alkylene carbonate, an alkyl alkoxyacetate, and an alkyl pyruvate.

As an organic solvent, you may use the mixed solvent which mixed the solvent which has a hydroxyl group in a structure, and the solvent which does not have a hydroxyl group.
As the solvent having a hydroxyl group and the solvent having no hydroxyl group, the above-mentioned exemplified compounds can be appropriately selected, but as the solvent containing a hydroxyl group, alkylene glycol monoalkyl ether or alkyl lactate is preferable, and propylene glycol monomethyl ether (PGME ), Propylene glycol monoethyl ether (PGEE), methyl 2-hydroxyisobutyrate, or ethyl lactate is more preferred.
Further, as the solvent having no hydroxyl group, alkylene glycol monoalkyl ether acetate, alkyl alkoxy propionate, a monoketone compound which may have a ring, cyclic lactone, or alkyl acetate is preferable. Among these, propylene glycol is preferable. Monomethyl ether acetate (PGMEA), ethyl ethoxy propionate, 2-heptanone, γ-butyrolactone, cyclohexanone, cyclopentanone or butyl acetate is more preferable, and propylene glycol monomethyl ether acetate, γ-butyrolactone, ethyl ethoxy propionate, cyclohexanone More preferred is cyclopentanone or 2-heptanone. Propylene carbonate is also preferred as the solvent having no hydroxyl group.
The mixing ratio (mass ratio) of the solvent having a hydroxyl group to the solvent having no hydroxyl group is preferably 1/99 to 99/1, more preferably 10/90 to 90/10, and 20/80 to 60/40. More preferable. A mixed solvent containing 50% by mass or more of a solvent having no hydroxyl group is preferable in view of coating uniformity.
The solvent preferably contains propylene glycol monomethyl ether acetate, and may be propylene glycol monomethyl ether acetate alone or a mixed solvent of two or more kinds containing propylene glycol monomethyl ether acetate.

<Preparation method>
The solid content of the resist composition used in the pattern formation method of the present invention is preferably 40% by mass or more, more preferably 40 to 60% by mass, and still more preferably 45 to 55% by mass.
The solid content is a mass percentage of the mass of the other components excluding the solvent with respect to the total mass of the resist composition.

The resist composition is preferably obtained by dissolving the above components in a predetermined solvent (preferably the above mixed solvent) and filtering it. 0.1 micrometer or less is preferable, as for the pore size of the filter used for filter filtration, 0.05 micrometer or less is more preferable, and 0.03 micrometer or less is still more preferable. The filter is preferably made of polytetrafluoroethylene, polyethylene or nylon. In the filter filtration, for example, as disclosed in JP-A-2002-62667, cyclic filtration may be performed, or filtration may be performed by connecting a plurality of types of filters in series or in parallel. The composition may also be filtered multiple times. Furthermore, the composition may be subjected to a degassing treatment and the like before and after the filter filtration.

The viscosity of the resist composition used in the pattern formation method of the present invention is preferably 100 to 5000 mPa · s, more preferably 300 to 3000 mPa · s, in terms of excellent coatability.
The viscosity can be measured with an E-type viscometer at 25 ° C.

Such a resist composition can be coated on a support to form a resist film. As a method of apply | coating a resist composition on a support body, a spin coating method is mentioned, for example.
The support is not particularly limited, and is generally used in a process of manufacturing a semiconductor such as an IC (Integrated Circuit) or a process of manufacturing a circuit substrate such as a liquid crystal or a thermal head, and other lithography processes of photofabrication. Substrates can also be used. Specific examples of the support include inorganic substrates such as silicon, SiO ₂ , and SiN.

In addition, if necessary, a resist underlayer film (for example, SOG (Spin On Glass), SOC (Spin On Carbon), and an antireflective film) may be formed between the resist film and the support. As a material which comprises a resist underlayer film, well-known organic type or inorganic type material can be used suitably.

<Use>
The resist composition used in the pattern formation method of the present invention relates to a resist composition which changes its property by reaction with irradiation of i-line. More specifically, the composition of the present invention can be used in a semiconductor production process such as IC, a circuit board production such as liquid crystal or thermal head, a mold structure for imprinting, other photofabrication process, or a lithographic printing plate Or a resist composition used for producing an acid curable composition. The pattern formed in the present invention can be used in an etching process, an ion implantation process, a bump electrode formation process, a rewiring formation process, MEMS (Micro Electro Mechanical Systems), and the like.

[Pattern formation method]
Hereinafter, the pattern formation method of the present invention will be described.
The pattern formed by the patterning method of the present invention is typically a negative pattern.

The film thickness of the resist film used in the pattern formation method of the present invention is preferably 15 μm or more, more preferably 16 μm or more, and still more preferably 18 μm or more for the purpose of increasing the number of processing steps. The upper limit is not particularly limited, and is, for example, 100 μm or less.
The film thickness of the pattern to be formed is preferably 15 μm or more, more preferably 16 μm or more, and still more preferably 18 μm or more, for the purpose of increasing the number of processing steps. The upper limit is not particularly limited, and is, for example, 100 μm or less.

The pattern formation method of the present invention is
(I) a step of exposing the resist film formed on the support using an i-line (exposure step), and
(Ii) developing the exposed resist film with a developer containing an organic solvent to form a pattern (developing step);
Have.

The pattern formation method of the present invention is not particularly limited as long as it includes the steps (i) and (ii), and may further include the following steps.
In the pattern formation method of the present invention, the exposure method in the (i) exposure step may be immersion exposure.
The pattern formation method of the present invention preferably includes (iii) a pre-heating (PB: PreBake) step before (i) the exposure step.
The pattern formation method of the present invention preferably includes (iv) a post exposure baking (PEB) step after (i) the exposure step and (ii) the development step.
In the pattern forming method of the present invention, it is also preferable to carry out (v) a post-development heating step without performing a rinse step described later after (ii) the development step.
The pattern formation method of the present invention may include (i) an exposure step a plurality of times.
The pattern formation method of the present invention may include (iii) a preheating step a plurality of times.
The pattern formation method of the present invention may include (iv) a post-exposure heating step a plurality of times.
The pattern formation method of the present invention may include (v) a heating step after development a plurality of times.

In the pattern formation method of the present invention, the above-mentioned (i) exposure step and (ii) development step can be carried out by generally known methods.

The heating temperature is preferably 70 to 160 ° C. and more preferably 80 to 150 ° C. in any of (iii) pre-heating step (iv) post-exposure heating step and (v) post-development heating step.
The heating time is preferably 30 to 300 seconds, and more preferably 30 to 180 seconds, in any of (iii) pre-heating step (iv) post-exposure heating step and (v) post-development heating step. Is more preferred.
The heating can be performed by means provided in the exposure device and the developing device, and may be performed using a hot plate or the like.

The light source used in the exposure process is i-ray (wavelength 365 nm).
The light source used in the exposure process may contain light of other wavelengths within the range that does not affect the pattern formation.

(Ii) A developer (also referred to as "organic developer") containing an organic solvent used in the development step is a ketone solvent, an ester solvent, an alcohol solvent, an amide solvent, an ether solvent, and a hydrocarbon solvent The developer is preferably a developer containing at least one organic solvent selected from the group consisting of solvents.

Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 2-heptanone (methyl amyl ketone), 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, Examples include cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methylnaphthyl ketone, isophorone, propylene carbonate and the like.

As ester solvents, for example, methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, pentyl acetate, isopentyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl Ether acetate, ethyl 3-ethoxy propionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, butyl lactate, butane And butyl acid, methyl 2-hydroxyisobutyrate, isoamyl acetate, isobutyl isobutyrate, and butyl propionate.

As the alcohol-based solvent, the amide-based solvent, the ether-based solvent, and the hydrocarbon-based solvent, the solvents disclosed in paragraphs <0715> to <0718> of US Patent Application Publication No. 2016/0070167 A1 can be used.

A plurality of the above solvents may be mixed, or may be mixed with a solvent other than the above or water.

Among them, the organic developer preferably contains an ester solvent, preferably contains an ester solvent having a boiling point of 130 ° C. or less, and more preferably contains butyl acetate.
The organic developer is preferably an ester solvent, more preferably an ester solvent having a boiling point of 130 ° C. or less, and still more preferably butyl acetate.

The water content of the developer as a whole is preferably less than 50% by weight, more preferably less than 20% by weight, still more preferably less than 10% by weight, particularly preferably less than 3% by weight, and most preferably substantially free of water preferable.
The content of the organic solvent relative to the developer is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass with respect to the total mass of the developer. Is particularly preferred.

The developer may contain an appropriate amount of a known surfactant as needed.

The content of the surfactant is usually 0.001 to 5% by mass, preferably 0.005 to 2% by mass, and more preferably 0.01 to 0.5% by mass, with respect to the total amount of the developer.

The developer may contain the acid diffusion control agent described above.

As a developing method, for example, a method of continuously discharging the developing solution onto the substrate rotating at a constant speed (rotation coating method), a developer while scanning the developing solution discharge nozzle on the substrate rotating at a constant speed (Dispensing method), immersing the substrate in a bath filled with the developer for a certain period of time (dip method), method of raising the developer on the surface of the substrate by surface tension and standing for a certain period of time (paddle) Method, and a method (spray method) of spraying a developing solution on the substrate surface.
Among them, the paddle method or the spray method is preferable as the development method, and the spray method is more preferable.
Here, scanning in the dynamic dispensing method means reciprocating the discharge nozzle on a line passing through the rotation center of the substrate.
Spraying in the spray method includes discharging the developer in a shower shape. Further, when discharging the developing solution in the spray method, the substrate may be rotated.

In the development step, the time for which the developing solution is supplied onto the resist film is preferably 30 seconds or more in total, more preferably 60 to 600 seconds, and more preferably 120 to 300 seconds, in terms of better rectangularity of the pattern. More preferable.
Incidentally, the time "the developer is supplied onto the resist film" is intended to be a time when the developer is newly supplied onto the resist film in the developing step. Further, when the developer is supplied onto the resist film more than once, the total time of the plurality of times is intended.

The temperature of the developing solution used in the developing step is preferably 30 to 60 ° C., more preferably 35 to 55 ° C., and still more preferably 40 to 50 ° C. from the viewpoint that the rectangularity of the pattern is more excellent.

(Iii) It is also preferable to include a step (rinsing step) of washing with a rinse liquid after the developing step.

The rinse solution used in the rinse step after the development step using a developer containing an organic solvent is not particularly limited as long as it does not dissolve the pattern, and a solution containing a general organic solvent, pure water and the like can be used. As the rinse solution, a rinse solution containing at least one organic solvent selected from the group consisting of hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents, and ether solvents is used. Is preferred.
Specific examples of the ketone-based solvent and the ester-based solvent include the same solvents as described in the developer containing an organic solvent.
As a rinse solution used for the rinse process in this case, a rinse solution containing a monohydric alcohol is also preferable.

Examples of the monohydric alcohol used in the rinse step include linear, branched or cyclic monohydric alcohol. Specifically, 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, 4-octanol, and methyl isobutyl carbinol. Examples of the monohydric alcohol having 5 or more carbon atoms include 1-hexanol, 2-hexanol, 4-methyl-2-pentanol, 1-pentanol, 3-methyl-1-butanol, and methyl isobutyl carbinol. .

A plurality of various components may be mixed, or may be mixed with an organic solvent other than the above.
10 mass% or less is preferable, 5 mass% or less is more preferable, and 3 mass% or less is still more preferable. When the water content is 10% by mass or less, good development characteristics can be obtained.

The rinse solution may contain an appropriate amount of surfactant.
In the rinse step, the substrate subjected to development using an organic developer is washed using a rinse solution containing an organic solvent. Although the method of the cleaning process is not particularly limited, for example, a method of continuously discharging the rinse liquid onto the substrate rotating at a constant speed (rotation coating method), and immersing the substrate in a bath filled with the rinse liquid for a fixed time Examples include a method (dip method) and a method of spraying a rinse liquid on the substrate surface (spray method).
Above all, it is preferable to carry out cleaning treatment by spin coating, and after cleaning, rotate the substrate at a rotation speed of 2,000 to 5,000 rpm (revolution per minute) to remove the rinse solution from the substrate. It is also preferable to include a heating step (Post Bake) after the rinsing step. By this heating step, the developer and the rinse solution remaining between the patterns and inside the patterns are removed. In the heating step after the rinsing step, the heating temperature is usually 40 to 160 ° C., preferably 70 to 95 ° C., and the heating time is usually 10 seconds to 3 minutes, preferably 30 seconds to 90 seconds.

It is preferable that various materials (for example, a solvent, a developer, or a rinse solution) used in the pattern formation method of the present invention do not contain impurities such as metal components, isomers, and residual monomers. The content of these impurities contained in the various materials described above is preferably 1 ppm or less, more preferably 100 ppt or less, still more preferably 10 ppt or less, and substantially not including it (the detection limit of the measuring device or less) Is particularly preferred.

As a method of removing impurities, such as a metal, from said various materials, the filtration using a filter is mentioned, for example. The pore size of the filter is preferably 10 nm or less, more preferably 5 nm or less, and still more preferably 3 nm or less. The material of the filter is preferably made of polytetrafluoroethylene, polyethylene or nylon. The filter may be a filter previously washed with an organic solvent. In the filter filtration step, plural types of filters may be connected in series or in parallel. When multiple types of filters are used, filters with different pore sizes and / or different materials may be used in combination. Also, the various materials may be filtered a plurality of times, and the step of filtering a plurality of times may be a circulation filtration step. As the filter, a filter with reduced eluate as disclosed in JP-A-2016-201426 is preferable.
In addition to filter filtration, removal of impurities by adsorbent may be performed, and filter filtration and adsorbent may be used in combination. As the adsorbent, known adsorbents can be used. For example, inorganic adsorbents such as silica gel or zeolite, or organic adsorbents such as activated carbon can be used. As a metal adsorption material, the filter indicated by JP, 2016-206500, A is mentioned, for example.
In addition, as a method of reducing impurities such as metals contained in the above-mentioned various materials, filter filtration is performed on the materials constituting the various materials, in which the material having a small metal content is selected as the materials constituting the various materials. And, the inside of the apparatus may be lined with Teflon (registered trademark) or the like, and distillation may be carried out under conditions that minimize contamination as much as possible. The preferable conditions in the filter filtration performed with respect to the raw material which comprises various materials are the same as the conditions mentioned above.

The various materials described above are preferably stored in the containers described in US Patent Application Publication No. 2015/0227049, Japanese Patent Application Laid-Open No. 2015-123351, and the like in order to prevent contamination of impurities.

A method of improving the surface roughness of the pattern may be applied to the pattern formed by the pattern forming method of the present invention. As a method of improving the surface roughness of the pattern, for example, a method of processing the pattern by plasma of a gas containing hydrogen disclosed in US Patent Application Publication No. 2015/0104957 can be mentioned. Besides, JP-A-2004-235468, U.S. Patent Application Publication No. 2010/0020297, and Proc. of SPIE Vol. 8328 83280N-1 "EUV Resist Curing Technique for LWR Reduction and Etch
Known methods as described in “Selectivity Enhancement” may be applied.
Also, the pattern formed by the above method can be used as a core of a spacer process disclosed in, for example, JP-A-3-270227 and US Patent Application Publication No. 2013/0209941.

[Method of manufacturing electronic device]
The present invention also relates to a method of manufacturing an electronic device, including the pattern forming method described above. The electronic device manufactured by the method of manufacturing an electronic device of the present invention is suitably installed in an electric / electronic device (for example, a home appliance, an office automation (OA) related device, a media related device, an optical device, a communication device, etc.) Be done.

Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, proportions, treatment contents, treatment procedures and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as limited by the following examples.

[Resist composition]
The various components contained in the resist composition used by the Example or the comparative example below are shown.

<Novolak resin>
Novolak resin (N-1)
Novolak resin EP 6050G (Asahi Organic Material Industry Co., Ltd., m-cresol / p-cresol = 40/60 (mass ratio), weight average molecular weight: 2500 to 4000 (catalog value)) of a phenolic hydroxyl group is acetalized to give the following general formula The group represented by (A) was bonded to obtain a novolak resin (N-1) represented by the following structural formula.
* Indicates a bonding position.
The acetalization rate (protection rate) of the novolak resin (N-1) was 30 mol%. The acetalization rate corresponds to the value of X in the structural formula of the following novolak resin. That is, the novolak resin (N-1) having an acetalization rate of 30 mol% corresponds to the case where X in the following structural formula is 30 mol%.

The above acetalization was carried out in the same manner, with reference to the description in paragraph <0407> of JP-A-2013-214053.
More specifically, triethylamine (9.00 g) was added to a mixed solution obtained by dissolving novolak resin EP 6050 G (10.0 g) in tetrahydrofuran (THF) (60 g), and the mixture was stirred in an ice water bath. The chloroether compound (12.50g) shown below was dripped at this mixed solution, and it stirred in an ice water bath for 4 hours.

Thereafter, distilled water was added to the mixed solution to stop the reaction. The THF was removed under reduced pressure and the resulting reaction was dissolved in ethyl acetate. The resulting organic phase was washed five times with distilled water, and then the organic phase was dropped into hexane (1.0 L) to precipitate a solid. The obtained solid was separated by filtration and washed with a small amount of hexane to obtain novolak resin (N-1) (11.7 g).

Novolak resin (N-2)
Novolak resin EPR 5030 G (m-cresol / p-cresol = 50/50 (mass ratio), weight average molecular weight: 4000 to 6500 (catalog value)) manufactured by Asahi Organic Materials Co., Ltd. is the same as novolak resin (N-1) The compound was acetalized to give a novolak resin (N-2) by coupling the group represented by the above general formula (A).
The acetalization rate was 32 mol%.

Novolak resin (N-3)
Novolak resin EP 4080 G (m-cresol / p-cresol = 60/40 (mass ratio), weight average molecular weight: 4000 to 6000 (catalog value)) manufactured by Asahi Organic Materials Co., Ltd. is the same as the novolak resin (N-1) The compound was acetalized to give a novolak resin (N-3) by coupling the group represented by the above general formula (A).
The acetalization rate was 29 mol%.

Novolak resin (N-4)
Novolak resin EP 6050G (Asahi Organic Material Industry Co., Ltd., m-cresol / p-cresol = 40/60 (mass ratio), weight average molecular weight: 2500 to 4000 (catalog value)) (10.0 g) tetrahydrofuran (THF) ( It was dissolved in 60 g to obtain a mixed solution. To this mixed solution was added 1-adamantane carbonyl chloride (14.88 g) and triethylamine (10.11 g), and the mixture was further stirred at 50 ° C. for 4 hours. After returning the mixed solution to room temperature, ethyl acetate (100 mL) and distilled water (100 mL) were added, and while stirring the mixed solution in ice water, 1 N aqueous HCl solution was added little by little to neutralize the mixed solution . The mixed solution was transferred to a separatory funnel, to which ethyl acetate (100 mL) and distilled water (100 mL) were further added, and after stirring, the aqueous phase was removed. Thereafter, the organic phase was washed five times with distilled water (200 mL), and the organic phase was concentrated and dropped into hexane (2 L) to precipitate a solid. Thereafter, the solid was separated by filtration and vacuum dried to obtain a novolak resin (N-4) (9.8 g).
The structure of novolac resin (N-4) is shown below.
The esterification rate (protection rate) of the novolak resin (N-4) was 28 mol%.

Novolak resin (N-5)
m-cresol was polymerized by using formaldehyde and salicylaldehyde in combination (formaldehyde / salicylaldehyde = 1 / 0.3 (mass ratio)) to obtain novolak resin N-5 (weight average molecular weight: 4000).

<Non-Novolak resin>
・ Resin (R-1)
Nippon Soda Co., Ltd. poly (p-hydroxystyrene) (VP2500) (20 g) was dissolved in tetrahydrofuran (THF) (120 mL) to obtain a mixed solution. After adding 1-adamantane carbonyl chloride (4.96 g) and triethylamine (3.37 g) to this mixed solution, the mixture was further stirred at 50 ° C. for 4 hours. After returning the mixed solution to room temperature, ethyl acetate (100 mL) and distilled water (100 mL) were added, and while stirring the mixed solution in ice water, 1 N aqueous HCl solution was added little by little to neutralize the mixed solution . The mixed solution was transferred to a separatory funnel, to which ethyl acetate (100 mL) and distilled water (100 mL) were further added, and after stirring, the aqueous phase was removed. Thereafter, the organic phase was washed five times with distilled water (200 mL), and the organic phase was concentrated and dropped into hexane (2 L) to precipitate a solid. Thereafter, the solid was separated by filtration and vacuum dried to obtain a resin (R-1) (20.6 g) for comparison.
The structure of the resin (R-1) is shown below. In the following structural formulas, units of “15” and “85” are intended to be mol%.

<Photo acid generator>
The following photoacid generators were used.
・ CPI-210S (made by San-Apro Corporation)

<Crosslinking agent>
The following crosslinkers were used:

· (L-1): the following compound

-(L-2): Nicarac MW 100-LM (methylated melamine resin, manufactured by Sanwa Chemical Co., Ltd., containing the following compounds)

-(L-3): Nicalac MX-270 (methylated urea resin, manufactured by Sanwa Chemical Co., Ltd., containing the compounds shown below)

-(L-4): the following compound

-(L-5): the following compound

<Acid diffusion control agent>
The following acid diffusion control agent was used.
・ Triethanolamine

<Surfactant>
The following surfactants were used.
・ Megafuck R-41 (made by DIC Corporation)

<Solvent>
The following solvents were used.
· Mixed solvent of PGMEA (propylene glycol monomethyl ether acetate) and PGME (propylene glycol monomethyl ether) (PGMEA / PGME = 50/50 (mass ratio))

The various components described above were mixed in the formulations shown in Table 1 to prepare resist compositions. The compounding amount of the solvent was adjusted so that the solid content of the resist composition became the value shown in Table 1.

[Formation of pattern]
(Examples 1 to 18 and 20, Comparative Examples 1 to 3)
Each of the obtained resist compositions was spin-coated on a silicon wafer (diameter: 8 inches, Bare-Si) and further heated on a hot plate at 100 ° C. for 120 seconds.
Thereafter, the resist film is subjected to exposure processing (wavelength: 365 nm, exposure amount: 1000 mJ / cm ² ) of a linear pattern of 100 μm using an i-line stepper exposure apparatus (FPA-3000i5 +, manufactured by Canon) Heated on a 130 ° C. hot plate for 60 seconds.

After the heating, the silicon wafer was fixed to a horizontal rotation table by a vacuum chuck method. Furthermore, while rotating the silicon wafer at 50 rpm, the developing solutions shown below from above the rotation center are continuously supplied for 30 seconds or 120 seconds at each temperature and continuously supplied from the jet nozzle in the form of a shower to perform development processing. (Spray method) Then, the silicon wafer was dried by rotating it at 2000 rpm for 30 seconds. Thereafter, the silicon wafer was heated on a 150 ° C. hot plate for 120 seconds to obtain a pattern.

(Example 19)
In the pattern forming method described above, the same procedure is carried out until the silicon wafer is fixed to the horizontal rotary table, and then, while the silicon wafer is kept stationary without being rotated, 40 ° C. from above the center of the silicon wafer. The butyl acetate (developer) was discharged for 3 seconds to spread the developer over the top surface of the silicon wafer. The developer was raised by surface tension on the silicon wafer, and was allowed to stand for 300 seconds without supplying a new developer (paddle method). Thereafter, pure water was discharged in the form of a shower to carry out a rinse treatment.
Furthermore, in the same manner as described above, a drying process and heating were performed on a silicon wafer to obtain a pattern.

[Evaluation]
The cross-sectional shape of the obtained pattern is observed using a field emission scanning electron microscope S-4800 (manufactured by Hitachi High-Technologies Corporation), and the rectangularity of the pattern is evaluated based on the angle of the contact portion between the silicon wafer and the pattern. went. As the angle is closer to 90 degrees, the rectangularity is more excellent.
The results are shown in Table 1.

<Developer>
Development was carried out using the following developer.
-Butyl acetate-Amyl acetate-MEK (methyl ethyl ketone)
・ TMAHaq (2.38 mass% tetramethyl ammonium hydroxide aqueous solution)
(However, in the case of using TMAHaq as a developer (Comparative Example 1), after performing the above-mentioned development processing, before performing drying processing, pure water was discharged like a shower to perform rinse processing)

Table 1 below shows the composition of the used resist composition, the conditions for development, and the results of evaluation in Examples and Comparative Examples.
In Table 1, the column of "resin type" indicates the type of resin used. "NV" means novolac resin, "PHS" means polyhydroxystyrene based resin.
In Table 1, the column of "resin content" represents the content (% by mass) of the resin relative to the total solid content in the resist film (resist composition).
In Table 1, the column "m / p" represents the ratio of the repeating unit derived from m-cresol to the repeating unit derived from p-cresol in the novolak resin used. (M-cresol / p-cresol (mass ratio))
In Table 1, the column of "Protection type" indicates the type of protection to phenolic hydroxyl group that the resin has. "Acetalization" means that a phenolic hydroxyl group is acetalized, and "esterification" means that a phenolic hydroxyl group is esterified.
In Table 1, the column "MOM group number" indicates the number of methoxymethyl groups possessed by the used crosslinking agent.
In Table 1, the column "number of OH groups" indicates the number of phenolic hydroxyl groups possessed by the used crosslinking agent.
In Table 1, the column of "film thickness" indicates the film thickness of the formed resist film.
In Table 1, the value in the parenthesis of the column "Developer" indicates the boiling point of the developer used.
In Table 1, the column of "Developer temperature" indicates the temperature of the developer when the developer is supplied from the jet nozzle in the development process.
In Table 1, the column of “Development method” indicates the development method used in the development step. "Spray" means spray method and "paddle" means paddle method.
In Table 1, the column of "supply time" indicates the total time for supplying the developer on the resist film in the developing step.

From the results shown in Table 1, it was confirmed that according to the pattern forming method of the present invention, a pattern excellent in rectangularity can be obtained.
When the acid dissociable group was bonded to the oxygen atom of the phenolic hydroxyl group of the novolak resin to form an acetal group, it was confirmed that the rectangularity of the pattern was more excellent (comparison of Examples 1 and 16).
When the resist film contains a crosslinking agent, the rectangularity of the pattern tends to be more excellent (comparison of Examples 1, 4, 5, 6, 7 and 17).
Moreover, when the crosslinking agent had 6 or more of methoxymethyl groups, the tendency for the rectangularity of a pattern to be more excellent was confirmed (comparison of Examples 4 and 5 and comparison of Examples 1, 6 and 7).
When the crosslinking agent had a phenolic hydroxyl group, the tendency for the rectangularity of the pattern to be more excellent was confirmed (comparison of Examples 5 and 6 and Comparison of Examples 1 and 4).
When the solid content of the resist composition was 40% by mass or more, it was confirmed that the rectangularity of the pattern was more excellent (comparison of Examples 8 and 20).
When the developing solution was an ester compound having a boiling point of 130 ° C. or less, a tendency was found that the rectangularity of the pattern was more excellent (comparison of Examples 1, 9 and 10).
When the temperature of the developing solution at the time of development was 30 to 60 ° C., the tendency for the rectangularity of the pattern to be more excellent was confirmed (comparison of Examples 11, 13 and 14 and Examples 12 and 15).
When the time for supplying the developing solution onto the resist film was 30 seconds or more in total, it was confirmed that the rectangularity of the pattern was more excellent (comparison of Examples 1, 18 and 19).
When the ratio (m-cresol / p-cresol) of the repeating unit derived from m-cresol to the repeating unit derived from p-cresol is 50/50 or less (the repeating unit derived from m-cresol is p In the case of being less than the repeating unit derived from cresol), the tendency for the rectangularity of the pattern to be more excellent was confirmed (comparison of Examples 1, 2 and 3).

Claims (14)

A resist film comprising a novolac resin and a photoacid generator that generates an acid upon i-line exposure, wherein the novolac resin content is 50% by mass or more with respect to the total solid content of the resist film. , I-line exposure step,
Developing the resist film with a developer containing an organic solvent to form a pattern;
Have in this order,
Pattern formation method. The pattern formation method according to claim 1, wherein the resist film further contains a crosslinking agent. The pattern formation method according to claim 2, wherein the crosslinking agent is a compound having a methoxymethyl group. The pattern formation method according to claim 3, wherein the compound having a methoxymethyl group has 6 or more methoxymethyl groups. The pattern formation method of Claim 3 or 4 in which the compound which has the said methoxymethyl group has phenolic hydroxyl group. The pattern forming method according to any one of claims 1 to 5, wherein the novolak resin has an acid dissociable group. The pattern forming method according to any one of claims 1 to 6, wherein the film thickness of the resist film is 15 μm or more. The resist film is formed using a resist composition containing the novolak resin and the photoacid generator.
The pattern forming method according to any one of claims 1 to 7, wherein a solid content of the resist composition is 40% by mass or more. The pattern forming method according to any one of claims 1 to 8, wherein the developer contains an ester solvent having a boiling point of 130 属 C or less. The pattern forming method according to any one of claims 1 to 9, wherein the developer contains butyl acetate. The pattern forming method according to any one of claims 1 to 10, wherein the temperature of the developer is 30 to 60 属 C. The pattern forming method according to any one of claims 1 to 11, wherein the step of forming the pattern includes the step of supplying the developer on the resist film for a total of 30 seconds or more. Novolak resin and photo acid generator that generates acid by i-line exposure
A resist composition used for the pattern forming method according to any one of claims 1 to 12. A method of manufacturing an electronic device, comprising the pattern forming method according to any one of claims 1 to 12.