JP6540379B2 - Pattern formation method - Google Patents

Description

  The present invention relates to a pattern formation method.

  With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, miniaturization of patterns in the lithography process is required. As one of the methods of micropatterning, a process (so-called "slimming process") is known in which the line width of the formed resist pattern is made smaller than the line width formed first.

  Conventionally, as a method of slimming treatment, a method of applying a solution containing an acid onto a substrate on which a resist pattern is formed, followed by heat treatment, and then cleaning is performed.

  In this method using a solution containing an acid, the amount of slimming largely depends on the type of resist material (the radiation sensitive resin composition) and the concentration of the acid. Therefore, in Japanese Patent Application Laid-Open No. 2010-267880, in order to obtain a constant slimming amount regardless of the type of resist material, the concentration of acid contained in the solution, the type of resist material and the corresponding slimming amount are made into a database It has been proposed.

  However, this database creation method is not a fundamental solution to the large dependence of the slimming amount depending on the type of resist material. In addition, in the method using a solution containing an acid, roughness occurs in the pattern after slimming, and there is a problem that LWR (Line Width Roughness) is large.

JP, 2010-267880, A

  The present invention has been made based on the above circumstances, and an object thereof is to provide a method capable of forming a fine pattern having a small LWR and exceeding the wavelength limit regardless of the type of resist material. is there.

  The invention made in order to solve the above-mentioned subject is the process (following, the 1st alkaline solution (it is also called "alkali solution (1)") in contact with the prepattern formed using radiation sensitive resin composition. A process of heating the pre-pattern in contact with the first alkaline solution (hereinafter also referred to as a heating process (A)), and the heated pre-pattern. And a step of washing with water or a second alkali solution (hereinafter, also referred to as “alkali solution (2)” (hereinafter, also referred to as “washing step (A)”), and the radiation sensitive resin composition A pattern forming method comprising a polymer (hereinafter also referred to as "[a] polymer") having a functional group whose solubility in the water or the second alkali solution changes by contact with a first alkali solution and heating. Less than," A first pattern forming method "is also referred to).

  Another invention made to solve the above problems is a step of exposing a coating film formed using a radiation sensitive resin composition (hereinafter also referred to as “exposure step (B)”), and A step of bringing a first alkaline solution into contact with the coated film (hereinafter also referred to as "contacting step (B)") and a step of heating the coated film brought into contact with the first alkaline solution (hereinafter referred to as "heating step (B And the step of washing the heated coating film with water or a second alkali solution (hereinafter also referred to as “contact step (B)”), and the radiation sensitive resin composition comprises [A] It is a pattern formation method containing a polymer (hereinafter, also referred to as “second pattern formation method”).

  According to the first pattern formation method of the present invention, the dependence of the slimming amount on the type of resist material is small. In addition, LWR is reduced in the obtained pattern. According to the second pattern formation method of the present invention, a fine pattern having a small LWR and exceeding the wavelength limit can be formed regardless of the type of the resist material. Therefore, these pattern formation methods can be suitably used for pattern formation in the semiconductor processing field etc. which is expected to be further miniaturized in the future.

It is a schematic diagram showing one embodiment of the 1st pattern formation method of the present invention.

<First Pattern Forming Method>
Hereinafter, the first pattern formation method of the present invention will be described using the drawings. The said pattern formation method is equipped with a contact process (A), a heating process (A), and a washing process (A). Each step will be described below.

<Contact process (A)>
This step is a step of bringing the alkaline solution (1) into contact with the pre-pattern formed using the radiation sensitive resin composition. In this step, the prepattern 2 formed on the substrate 1 shown in FIG. 1 (A) is placed in contact with the alkaline solution 3 as shown in FIG. 1 (B). The pre-pattern 2 is formed using a radiation sensitive resin composition.

[Radiation sensitive resin composition]
The radiation sensitive resin composition contains a polymer [a]. Moreover, the radiation sensitive resin composition may contain [b] radiation sensitive acid generator as a suitable component. Moreover, the radiation sensitive resin composition may contain the other component within the range which does not impair the effect of this invention. Each component will be described below.

([A] polymer)
[A] The polymer has a functional group whose solubility in water or the alkaline solution (2) changes by contact with the alkaline solution (1) and heating. That is, the polymer [a] has a structural unit having this functional group at any of the terminal, main chain and side chain (hereinafter also referred to as structural unit (I)). This functional group contributes to slimming of the prepattern due to the change in solubility as described later. From the viewpoint of the ease of introduction of the functional group and the ease of adjustment of the introduction amount, in the structural unit (I), the side chain preferably has this functional group.

  The functional group is not particularly limited as long as the solubility in water or the alkaline solution (2) is changed by the contact with the alkaline solution (1) and heating, but a lactone ring group, a carbonate ring group and a sultone ring group are preferable. And lactone ring groups are more preferred. The ring possessed by these groups is cleaved by contact with the alkaline solution (1) and heating, and the solubility of these groups in water or the alkaline solution (2) changes. It is known that a prepattern produced using a resist material containing a polymer having a lactone ring group, a carbonate ring group or a sultone ring group has high adhesion to a substrate, and such a resist material is frequently used It is done. Therefore, selecting a lactone ring group, a carbonate ring group, and a sultone ring group as the functional group whose solubility changes is because the conventional radiation-sensitive resin composition can be used, and hence the easiness of implementation and the type of resist material In terms of the breadth of choice of

  [A] The polymer preferably has an acid dissociable group. [A] When the polymer has an acid dissociable group, the radiation sensitive resin composition can easily exhibit radiation sensitivity suitable as a resist material. [A] The polymer may have acid dissociability at any of the terminal, main chain and side chain, and in view of easiness of introduction of acid dissociability and easiness of adjustment of the introduction amount, the side chain Preferably have this functional group.

  Therefore, the polymer [a] preferably has a structural unit containing at least one selected from the group consisting of a lactone ring group, a carbonate ring group and a sultone ring group. The polymer [a] preferably has a structural unit containing an acid dissociable group (hereinafter also referred to as “structural unit (II)”). [A] Examples of other structural units that may be contained in the polymer include structural units having a hydrophilic functional group (hereinafter also referred to as “structural unit (III)”), and the [a] polymer is You may have other structural units other than these structural units. [A] The polymer may have one or more of each structural unit. Each structural unit will be described below.

(Structural unit (I))
Structural unit (I) is a structural unit having a functional group whose solubility in water or alkaline solution (2) changes at any of the terminal, main chain and side chain by contact with alkaline solution (1) and heating . Examples of the structural unit (I) include structural units represented by the following formula, and the like.

In the above formula, R ^L1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  As a lower limit of the content rate of structural unit (I), 30 mol% is preferable with respect to all the structural units which comprise a [a] polymer, and 35 mol% is more preferable. As an upper limit of the said content rate, 70 mol% is preferable and 65 mol% is more preferable. By setting the content ratio of the structural unit (I) in the above range, slimming of the pre-pattern can be more easily performed by the pattern forming method.

(Structural unit (II))
Structural unit (II) is a structural unit containing an acid dissociable group. Examples of the structural unit (II) include structural units represented by the following formula (1).

In the above formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^p is a monovalent acid dissociable group.

The monovalent acid-dissociable group represented by R ^p is preferably a group represented by the following formula (i).

In said formula (i), R ^<p1> is a C1-C20 monovalent hydrocarbon group. R ^p2 and R ^p3 are each independently a monovalent linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon having 3 to 20 carbon atoms, or these groups are mutually different It represents an alicyclic structure having 3 to 20 ring members which is combined with the carbon atom to which they are bonded.

As a C1-C20 monovalent hydrocarbon group represented by said R ^p1 , a C1-C20 monovalent | monohydric chain hydrocarbon group, a C3-C20 monovalent | monohydric alicyclic group is mentioned, for example A hydrocarbon group, a C6-C20 monovalent | monohydric aromatic hydrocarbon group, etc. are mentioned.

As a C1-C20 monovalent | monohydric chain hydrocarbon group represented by said R ^<p1> , R ^<p2> and R ^<p3> , a methyl group, an ethyl group, n-propyl group, i-propyl group, n-butyl is mentioned, for example Groups, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like.

The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 is, for example, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclo A cycloalkyl group such as octyl group, cyclodecyl group, cyclododecyl group, norbornyl group, adamantyl group, tricyclodecyl group, tetracyclododecyl group;
And cycloalkenyl groups such as cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group, cyclooctenyl group, cyclodecenyl group, norbornenyl group, tricyclodecenyl group, tetracyclododecenyl group and the like.

As a C6-C20 monovalent | monohydric aromatic hydrocarbon group represented by said R ^<p1> , R ^<p2> and R ^<p3 > aryl groups, such as a phenyl group, a tolyl group, xylyl group, a naphthyl group, an anthryl group;
And aralkyl groups such as benzyl group, phenethyl group and naphthylmethyl group.

Among these, an adamantane structure or a cycloalkane composed of R ^p1 is a monovalent C 1-10 hydrocarbon chain chain hydrocarbon group, and the R ^p2 and R ^p3 groups are combined together and together with the carbon atoms to which they are attached. It is preferred to represent the structure.

  Examples of the structural unit (II) include structural units represented by the following formulas (1-1) to (1-4), and the like.

In the above formula (1-1) ~ (1-4), ^{R 1} is as defined in the above formula (1). R ^p1 , R ^p2 and R ^p3 are as defined in the above formula (i). n _p is an integer of 1 to 4;

  As a structural unit represented by said Formula (1) or (1-1)-(1-4), the structural unit etc. which are represented by a following formula are mentioned, for example.

In said formula, R ¹ is synonymous with said formula (1).

  Examples of the monomer giving the structural unit (II) include (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (meth) acrylic acid- 2-Methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid 1-((meth) acrylic acid Bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, 1-methyl (meth) acrylic acid -1-cyclopentyl ester, (meth) acrylic acid 1-ethyl-1-cyclopentyl ester, (meth) acrylic acid 1-methyl-1-cyclohexyl ester, Data), and acrylic acid 1-ethyl-1-cyclohexyl ester.

  As a lower limit of the content rate of structural unit (II), 30 mol% is preferable with respect to all the structural units which comprise a polymer, and 35 mol% is more preferable. As an upper limit of the said content rate, 70 mol% is preferable and 65 mol% is more preferable. By making the content rate of structural unit (II) into the said range, according to the said pattern formation method, the pattern of a more favorable shape can be formed.

(Structural unit (III))
Structural unit (III) is structural unit (III) having a hydrophilic functional group. [A] The adhesion between the prepattern and the substrate is improved by the polymer having the structural unit (III), and as a result, according to the pattern forming method, a pattern having a better shape may be formed. it can.

  As said hydrophilic functional group, a hydroxy group, a carboxy group, an amino group, an oxo group (= O), a sulfonamide group, a cyano group, a nitro group etc. are mentioned, for example. Of these, hydroxy is preferred.

  As structural unit (III), the structural unit etc. which are represented by a following formula are mentioned, for example.

In the above formulae, R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

  As a content rate of structural unit (III), 0 mol% or more and 40 mol% or less are preferable with respect to all the structural units which comprise a [a] polymer, and 0 mol% or more and 30 mol% or less are more preferable. By making the content rate of structural unit (III) into the said range, according to the said pattern formation method, the resist pattern of a still more favorable shape can be formed.

  [A] The polymer may have other structural units other than the above structural units. As another structural unit, for example, a structural unit containing a non-acid dissociative chain hydrocarbon group, a structural unit containing a non acid dissociative alicyclic hydrocarbon group, etc. may be mentioned. The content ratio of the above-mentioned other structural units is usually 30 mol% or less, preferably 20 mol% or less, with respect to all the structural units constituting the [a] polymer. When the content rate of the said other structural unit exceeds the said upper limit, the pattern formation property of a radiation sensitive resin composition may fall.

  The content of the polymer [a] is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more, based on the total solid content of the radiation sensitive resin composition.

([A] Polymer synthesis method)
[A] A polymer can be synthesized, for example, by polymerizing monomers giving each structural unit in a suitable solvent using a radical polymerization initiator.

  As a radical polymerization initiator, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis ( Azo-based radical initiators such as 2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate; benzoyl peroxide, t- Examples thereof include peroxide-based radical initiators such as butyl hydroperoxide and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred. Two or more of these radical initiators may be used.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane and n-decane; cyclohexane, cycloheptane, cyclooctane, decalin, norbornane etc. Cycloalkanes; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene and cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene and the like;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, methyl propionate and the like;
Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes and diethoxyethanes;
Alcohols, such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2- pentanol, etc. are mentioned. These solvents may be used alone or in combination of two or more.

  The reaction temperature in the above polymerization is usually 40 ° C. or more, preferably 50 ° C. or more, and is usually 150 ° C. or less, preferably 120 ° C. or less. The reaction time is usually 1 hour or more, and usually 48 hours or less, preferably 24 hours or less.

  [A] The weight average molecular weight (Mw) of the polymer by gel permeation chromatography (GPC) is preferably 1,000 or more. On the other hand, as Mw, 100,000 or less is preferable, 50,000 or less is more preferable, 30,000 or less is especially preferable. [A] By making Mw of a polymer into the said range, according to the said pattern formation method, the pattern of a still more favorable shape can be formed.

  [A] The ratio (Mw / Mn) of the Mw of the polymer to the number average molecular weight (Mn) is usually 1 or more and 3 or less, preferably 1 or more and 2 or less.

Mw and Mn of the polymer are values measured by GPC using a Tosoh GPC column (two “G2000 HXL”, one “G3000 H XL”, one “G 4000 H XL”) under the following conditions.
Eluent: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential Refractometer Standard substance: Monodispersed polystyrene

([B] Radiation-sensitive acid generator)
[B] The radiation sensitive acid generator is a substance which generates an acid upon irradiation (exposure) of radiation. In a preferred embodiment of the pattern formation method, the polymer [a] further has an acid dissociable group, and the radiation sensitive resin composition further contains a radiation sensitive acid generator. [A] The polymer causes the acid dissociable group in the [a] polymer to be dissociated by the action of the acid generated by the above [b] radiation-sensitive acid generator to form a carboxy group etc., as a result, [A] The solubility of the polymer in the developer changes. As a containing form of [b] radiation-sensitive acid generator in the said radiation sensitive resin composition, the form of a low molecular weight compound which is mentioned later (Hereafter, it is also suitably called "[b] radiation sensitive acid generator") However, it may be in the form of being incorporated into a polymer or in the form of both of them.

  [B] Examples of the radiation sensitive acid generator include onium salt compounds, N-sulfonyloxyimide compounds and the like.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts and the like.

  As a sulfonium salt, for example, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1-difluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4 -Cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-cyclohexyl Phenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyl Diphenyl sulfonium camphor sulfonate, 4-methanesulfonyl phenyl diphenyl sulfonium trifluoromethane sulfonate, 4-methane sulfonyl phenyl diphenyl sulfonium nonafluoro-n-butane sulfonate, 4-methane sulfonyl phenyl diphenyl sulfonium perfluoro-n-octane sulfonate, 4-methane sulfonyl Phenyldiphenylsulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluro Roethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) hexane-1-sulfonate, triphenylsulfonium 2- ( 1-adamantyl) -1,1-difluoroethane sulfonate etc. are mentioned.

  Examples of tetrahydrothiophenium salts include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophen -Bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 1- (6-n-butoxynaphthalen-2-yl) Trahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydro Thiophenium perfluoro-n-octane sulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2 , 2-tetrafluoroethane sulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate , 1- (3,5-dimethyl-4) Hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-) 4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethane sulfonate, 1- (3,5-dimethyl-4-hydroxyl) And phenyl) tetrahydrothiophenium camphorsulfonate and the like.

  Examples of iodonium salts include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl- 1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, Bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2.2 1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like.

Examples of the N-sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) ) Bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2 , 3-dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept- 5-ene-2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoro-ethanone Sulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3 -Dicarboximide etc. are mentioned.

  [B] The radiation-sensitive acid generator is preferably an onium salt compound, more preferably a sulfonium salt. [B] The radiation sensitive acid generator may be used alone or in combination of two or more.

  When the content of the radiation-sensitive acid generator is [b] radiation-sensitive acid generator, the content of the radiation-sensitive acid generator [b] is 100 parts by mass of the polymer [a], Usually, it is 0.1 parts by mass or more, preferably 0.5 parts by mass or more. On the other hand, the content is usually at most 20 parts by mass, preferably at most 15 parts by mass. [B] If the content of the radiation sensitive acid generator is less than the above lower limit, the sensitivity and developability of the radiation sensitive resin composition may be lowered. On the other hand, when the content of the radiation-sensitive acid generator [b] exceeds the above upper limit, the transparency to radiation may be lowered, and it may be difficult to obtain a desired resist pattern.

(Other ingredients)
Other components include, for example, [c] solvent, polymer having a higher fluorine atom content than [d] [a] polymer, [e] acid diffusion controller, [f] surfactant, [g] alicyclic Formula skeleton-containing compounds, [h] sensitizers and the like can be mentioned.

([C] solvent)
[C] The solvent is not particularly limited as long as it can dissolve or disperse the polymer [a] and other components. [C] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents and the like.

Examples of the alcohol solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol , Sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethyl Hexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethyl nonyl alcohol, sec-tetradecyl alcohol, s monoalcohol solvents such as ec-heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol and diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl 1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol and the like;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethyl butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

Examples of the ether solvents include difatty ethers such as diethyl ether, dipropyl ether and dibutyl ether;
Diaromatic ethers such as diphenyl ether, ditolyl ether;
Aromatic-aliphatic ethers such as anisole, phenylethyl ether and the like can be mentioned.

Examples of the ketone solvents include acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl iso-butyl ketone, methyl amyl ketone, ethyl n-butyl ketone and methyl n-hexyl ketone Aliphatic ketone solvents such as di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone and the like;
Aliphatic-aromatic ketone solvents such as acetophenone, propiophenone and tolyl methyl ketone;
Aromatic ketone solvents such as benzophenone, tolyl phenyl ketone, ditolyl ketone and the like can be mentioned.

Examples of the amide solvents include N, N'-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide , N-methyl propionamide, N-methyl pyrrolidone and the like.

Examples of the ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, acetic acid 3-methoxybutyl, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl acetate cyclohexyl, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, methoxytriglycol acetate, ethyl propionate Monoester solvents such as n-butyl propionate, iso-amyl propionate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate and the like;
Diester solvents such as glycol diacetate, diethyl oxalate, di-n-butyl oxalate, diethyl malonate, dimethyl phthalate and diethyl phthalate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether Polyhydric alcohol monoether acetate solvents such as acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Lactone solvents such as γ-butyrolactone and γ-valerolactone;
Carbonate solvents such as diethyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate and the like can be mentioned.

Examples of hydrocarbon solvents include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane , Aliphatic hydrocarbon solvents such as methylcyclohexane;
Aromatics such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene, n-amylnaphthalene Group hydrocarbon solvents and the like.

  Among these, as the solvent [c], ester solvents and ketone solvents are preferable. As ester solvents, polyhydric alcohol monoether acetate solvents and lactone solvents are preferable, and propylene glycol monomethyl ether acetate and γ-butyrolactone are more preferable. As a ketone solvent, a cyclic ketone solvent is preferable, and cyclohexanone is more preferable.

([D] polymer)
[D] The polymer is a polymer having a fluorine atom content higher than that of the [a] polymer. When the above radiation sensitive resin composition contains the [d] polymer, when the resist film is formed, the oil repellency characteristic of the [d] polymer tends to cause the distribution to be unevenly distributed in the surface of the resist film. is there. As a result, when liquid immersion exposure is performed, it is possible to suppress the elution of the acid generator, acid diffusion control agent and the like into the immersion medium, which is preferable. Further, by the water repellent feature of the polymer [d], the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the generation of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium becomes high, and high speed scan exposure becomes possible without leaving water droplets. In addition, a fluorine atom content rate (mass%) can obtain | require and calculate the structure of a polymer by measuring ¹³ C-NMR, ¹ H-NMR, IR spectrum etc.

  The [d] polymer is not particularly limited as long as the fluorine atom content is higher than that of the [a] polymer, but it is preferable to have a fluorinated alkyl group. [D] The polymer is formed by polymerization using at least one or more monomers containing a fluorine atom in the structure. As a monomer containing a fluorine atom in the structure, a monomer containing a fluorine atom in the main chain, a monomer containing a fluorine atom in the side chain, a monomer containing a fluorine atom in the main chain and the side chain, etc. Can be mentioned.

  As a monomer containing a fluorine atom in the main chain, for example, α-fluoro acrylate compound, α-trifluoromethyl acrylate compound, β-fluoro acrylate compound, β-trifluoromethyl acrylate compound, α, β-fluoro acrylate compound, Examples thereof include α, β-trifluoromethyl acrylate compounds and compounds in which one or more kinds of vinyl moieties have a hydrogen atom substituted with a fluorine atom or a trifluoromethyl group.

  As a monomer containing a fluorine atom in the side chain, for example, those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorine atom or a fluoroalkyl group or a derivative thereof, a fluoroalkyl group of acrylic acid or methacrylic acid or The ester compound which has the derivative group, the monomer whose side chain (site which does not contain a double bond) of 1 or more types of olefins is a fluorine atom or a fluoroalkyl group, or its derivative group etc. are mentioned.

  As a monomer containing a fluorine atom in the main chain and side chain, for example, α-fluoroacrylic acid, β-fluoroacrylic acid, α, β-fluoroacrylic acid, α-trifluoromethylacrylic acid, β-trifluoro An ester compound having a fluoroalkyl group such as methyl acrylic acid or α, β-trifluoromethyl acrylic acid or a derivative group thereof, a compound in which a hydrogen atom of one or more vinyl sites is substituted with a fluorine atom or a trifluoromethyl group A monomer substituted with a fluorine atom or a fluoroalkyl group or a derivative thereof, a hydrogen atom bonded to a double bond of one or more alicyclic olefin compounds, a fluorine atom or a trifluoromethyl group, etc. And monomers in which the side chain is a fluoroalkyl group or a derivative thereof. In addition, this alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  [D] As an embodiment in which the polymer has a fluorine atom, it is preferable to contain a structural unit (IV) represented by the following formula (F1).

In the above formula (F1), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁴ is a linear or branched alkyl group having 1 to 6 carbon atoms having at least one fluorine atom, a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a derivative thereof. k is an integer of 1 to 3; However, when R ⁴ is plural, plural R ⁴ may be the same or different. A is a single bond or a (k + 1) -valent linking group.

  Examples of the (k + 1) -valent linking group represented by A above include an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amido group, a sulfonylamide group, a urethane group, and a carbonyloxy-di (oxycarbonyl) ethanediyl Group, carbonyloxy-di (oxycarbonyl) propanediyl group, tri (carbonyloxy) ethanediyl group, carbonyloxy-tri (oxycarbonyl) ethanediyl group, carbonyloxy-tri (oxycarbonyl) propanediyl group, tetra (carbonyloxy) group Ethanediyl group etc. are mentioned.

  As a monomer giving a structural unit (IV), trifluoromethyl (meth) acrylic acid ester, 2,2,2- trifluoroethyl (meth) acrylic acid ester, perfluoroethyl (meth) acrylic acid ester, Per Fluoro n-propyl (meth) acrylic ester, perfluoro i-propyl (meth) acrylic ester, perfluoro n-butyl (meth) acrylic ester, perfluoro i-butyl (meth) acrylic ester, perfluoro t -Butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylic acid ester, 1- (2,2,3,3,4,4,4 5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic acid Stel, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7,7,8 , 8, 9, 9, 10, 10, 10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6- Octafluorohexyl) (meth) acrylic acid ester and 2,2-di (2,2,2-trifluoroethyloxycarbonyl) ethyl (meth) acrylic acid ester are preferable, and 2,2,2-trifluoroethyl (meth) acrylic acid ester is preferable. More preferred are acrylic acid esters and 2,2-di (2,2,2-trifluoroethyloxycarbonyl) ethyl (meth) acrylic acid esters.

  [D] The polymer may have two or more structural units (IV). The content ratio of the structural unit (IV) is usually 5 mol% or more, preferably 10 mol% or more, and more preferably 15 mol% or more based on all structural units in the polymer [d]. If the content ratio of the structural unit (IV) is less than 5 mol%, a receding contact angle of 70 ° or more can not be achieved, and elution of an acid generator or the like from the resist film may not be suppressed.

  [D] The polymer contains, besides the structural unit (IV), at least one selected from the group consisting of a lactone ring group, a carbonate ring group and a sultone ring group in order to control the dissolution rate in a developer. The structural unit (I) in the polymer [a], the structural unit (II) in the polymer [a] containing an acid dissociable group, and other structural units such as a structural unit containing an alicyclic hydrocarbon group It can contain more than species.

  As a structural unit containing the said alicyclic hydrocarbon group, the structural unit etc. which are represented, for example by a following formula (F2) are mentioned.

In the above formula (F2), R ⁵ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X is a C4-C20 monovalent | monohydric alicyclic hydrocarbon group.

As a C4-C20 monovalent | monohydric alicyclic hydrocarbon group represented by said X, a cyclobutane, cyclopentane, a cyclohexane, bicyclo [2.2.1] heptane, bicyclo [2.2.2] are mentioned, for example. Octane, tricyclo [5.2.1.0 ^2,6 ] decane, tetracyclo [6.2.1.1 ^3,6 . Examples thereof include hydrocarbon groups consisting of alicyclic rings derived from cycloalkanes such as 0 ^2,7 ] dodecane and tricyclo [3.3.1.1 ^3,7 ] decane.

  The content ratio of the other structural unit is usually 90 mol% or less, preferably 80 mol% or less, based on all structural units constituting the polymer [d].

  The content of the polymer (d) is preferably 0.1 parts by mass or more, and more preferably 1 part by mass or more, with respect to 100 parts by mass of the polymer (a). On the other hand, 20 mass parts or less are preferable, and, as for the said content, 10 mass parts or less are more preferable. [D] By setting the content of the polymer in the above range, the water repellency of the surface of the resist film to be formed can be more appropriately enhanced.

(Method for synthesizing [d] polymer)
As a method of synthesizing the polymer [d], for example, it can be synthesized according to the same method as the method of synthesizing the polymer [a]. [D] Mw of the polymer is preferably 1,000 or more, and 50,000 or less is preferable, 30,000 or less is more preferable, and 10,000 or less is more preferable. [D] If the Mw of the polymer is less than 1,000, a sufficient advancing contact angle may not be obtained.

([E] acid diffusion controller)
[E] The acid diffusion controller controls the diffusion phenomenon of the acid or the like generated from the radiation-sensitive acid generator by exposure in the resist film and exhibits an effect of suppressing undesirable chemical reaction in the non-exposed region. . In addition, the [e] acid diffusion controller also has the effect of improving the storage stability of a radiation sensitive resin composition containing the same. [E] The form of inclusion in the radiation sensitive resin composition of the acid diffusion control body is incorporated as a part of the polymer even in the form of a free compound (hereinafter appropriately referred to as “[e] acid diffusion control agent” as appropriate) Or both.

  [E] Examples of the acid diffusion control agent include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

  Examples of amine compounds include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4 -Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1, -Bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) ether Bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, N, N, N ', N'-tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N' , N ′ ′, N ′ ′-pentamethyldiethylene triamine and the like.

  Examples of the amide group-containing compound include N-t-butoxycarbonyl group-containing amino compounds such as N- (t-butoxycarbonyl) -4-hydroxypiperidine, N- (t-pentyloxycarbonyl) -4-hydroxypiperidine and the like. N-tert-Pentyloxycarbonyl group-containing amino compounds, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methyl Pyrrolidone, N-acetyl-1-adamantylamine, tris (2-hydroxyethyl) isocyanurate and the like can be mentioned.

  Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea and the like. Can be mentioned.

  Nitrogen-containing heterocyclic compounds include, for example, imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinazoline, purine, pyrrolidine, piperidine, piperidine ethanol, 2-quinoxalinol, 3-piperidino-1,2-propane Diol, morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane etc. are mentioned.

  [E] As the acid diffusion control agent, it is also possible to use a photodisintegrable base which is photosensitive upon exposure to generate a weak acid. As an example of a photodisintegrable base, the onium salt compound etc. which are decomposed | disassembled by exposure and loses acid diffusion controllability are mentioned. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (K1), an iodonium salt compound represented by the following formula (K2), and the like.

In formulas (K1) and (K2), R ^{6 to} R ¹⁰ each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group or a halogen atom. Z ^- and ^E - ^{are, OH -, R A -COO -} , R A -SO 3 -, R A -N - is an anion represented by _-SO 2 -R ^B or formula (K3). However, R ^A is an alkyl group, an aryl group or an alkaryl group. R ^B is an alkyl group which may have a fluorine atom.

In the above formula (K3), R ¹¹ is a linear or branched alkyl group having 1 to 12 carbon atoms in which a part or all of hydrogen atoms may be substituted with a fluorine atom, or 1 to 12 carbon atoms Or a linear or branched alkoxy group of u is an integer of 0 to 2;

([F] surfactant)
[F] Surfactants have the effect of improving coatability, striation, developability and the like. [F] As the surfactant, those similar to those used for general resist materials can be used.

([G] alicyclic skeleton-containing compound)
[G] The alicyclic skeleton-containing compound exhibits an effect of improving dry etching resistance, pattern shape, adhesion to a substrate, and the like.

[G] Examples of alicyclic skeleton-containing compounds include adamantane derivatives such as 1-adamantane carboxylic acid, 2-adamantanone, and t-butyl 1-adamantane carboxylic acid;
Deoxycholic acid esters such as t-butyl deoxycholic acid, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonyl methyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . ^17,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane and the like. The content of the [g] alicyclic skeleton-containing compound in the radiation sensitive resin composition is usually 5 parts by mass or less with respect to 100 parts by mass of the [a] polymer.

([H] Sensitizer)
[H] The sensitizer represents the action of increasing the amount of acid generated from the radiation-sensitive acid generator [b], and has the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition. Play.

  [H] Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. These sensitizers may be used in combination of two or more.

[Method of preparing radiation sensitive resin composition]
The radiation sensitive resin composition can be prepared, for example, by mixing the [a] polymer and other components in a predetermined ratio. The total solid content concentration of the radiation sensitive resin composition is usually 1% by mass or more and 50% by mass or less, preferably 1% by mass or more and 25% by mass or less.

[Pre-pattern formation method]
The prepattern can be formed according to known methods. Specifically, for example, a step of forming a coating film (resist film) using a radiation sensitive resin composition (hereinafter, also referred to as “resist film forming step”), a step of exposing the resist film (hereinafter, “exposure step” A pre-pattern can be formed by performing the step of (A) and the step of developing the exposed resist film (hereinafter, also referred to as a “development step”).

[Resist film formation process]
At this process, a resist film is formed using the said radiation sensitive resin composition. The resist film is usually formed on the upper surface side of the substrate. Examples of the substrate include a silicon wafer, a silicon dioxide, and a wafer coated with an antireflective film. The above radiation sensitive resin composition is coated on this substrate and the like. Examples of the coating method include spin coating, cast coating, roll coating, and the like. Specifically, after the above radiation sensitive resin composition is applied so that the resist film to be obtained has a predetermined film thickness, the solvent in the coating film is volatilized by soft baking (SB) or the like, and the resist Form a film. The temperature of SB is usually 60 ° C. or more, preferably 80 ° C. or more, while it is usually 140 ° C. or less, preferably 130 ° C. or less. The time of SB is usually 5 seconds or more, preferably 10 seconds or more, while it is usually 600 seconds or less, preferably 180 seconds or less.

  In the case of performing immersion exposure, in the case where the above-mentioned radiation sensitive resin composition does not contain a water repellent polymer additive, etc., it is possible to directly form the immersion liquid and the resist film on the resist film formed above. In order to avoid contact, a protective film for immersion that is insoluble in the immersion liquid may be provided. As the liquid immersion protective film, a solvent peelable protective film (see, for example, JP-A-2006-227632) which is peeled off by a solvent before the development step, a developer peelable protective film (for example, peel off simultaneously with the development of the development step) Any of WO 2005-069076 and WO 2006-035790 may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type liquid immersion protective film.

[Exposure process (A)]
At this process, the resist film formed at the said resist film formation process is exposed. This exposure is performed through a photomask, and in the case of immersion exposure, through an immersion medium such as water. Examples of the exposure light include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, and γ-rays; charged particle beams such as electron beams and α-rays, depending on the line width of the target pattern. Among these, far ultraviolet rays and electron beams are preferable, far ultraviolet rays are more preferable, ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm) are more preferable, and ArF excimer laser light is particularly preferable.

  After the exposure, post-exposure baking (PEB) is carried out, and in the exposed part of the resist film, the acid dissociable group of the polymer [a] polymer by the acid generated from the radiation-sensitive acid generator [b] by exposure. It is preferable to promote dissociation. The PEB causes a difference in the solubility of the exposed portion (exposed portion) and the non-exposed portion (unexposed portion) in the developer. The PEB temperature is usually 50 ° C. or more, preferably 80 ° C. or more, and is usually 180 ° C. or less, preferably 130 ° C. or less. The PEB time is usually 5 seconds or more, preferably 10 seconds or more, while it is usually 600 seconds or less, preferably 300 seconds or less.

[Development process]
At this process, the resist film exposed at the said exposure process is developed. Thereby, a predetermined pre-pattern which is a resist pattern can be formed.

  As the developing solution used for the above-mentioned development, in the case of alkali development, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n -Propylamine, triethylamine, methyl diethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, A third alkaline solution (hereinafter also referred to as an alkaline solution (3)) in which at least one alkaline compound such as 1,5-diazabicyclo- [4.3.0] -5-nonene is dissolved, etc. may be mentioned. The alkaline solution (3) is in particular an aqueous alkaline solution. Among these, TMAH aqueous solution is preferable and 2.38 mass% TMAH aqueous solution is more preferable. In the case of organic solvent development, organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents and the like, or solvents containing organic solvents can be mentioned. As said organic solvent, 1 type (s) or 2 or more types of the solvent listed as [c] solvent of the above-mentioned radiation sensitive resin composition, etc. are mentioned, for example. Among these, ester solvents and ketone solvents are preferable. As an ester solvent, an acetic acid ester solvent is preferable, and n-butyl acetate is more preferable. As a ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable.

  An appropriate amount of surfactant can be added to the developer as needed. As the surfactant, for example, an ionic or non-ionic fluorine-based and / or silicon-based surfactant can be used.

  As a developing method, for example, a method of immersing a substrate in a bath filled with a developer for a certain time (dip method), a method of raising a developer on the substrate surface by surface tension and developing by standing for a certain time (paddle method A method of spraying a developer onto the substrate surface (spray method), a method of continuously coating a developer onto a substrate rotating at a constant speed while scanning a developer coating nozzle at a constant speed (dynamic dispense method) Etc.

  After development, it may be washed with a rinse solution such as water or alcohol and dried.

  Examples of pre-patterns formed in this process include line-and-space patterns and hole patterns.

  In the said pattern formation method, it is preferable that a pre-pattern is a positive pre-pattern formed by developing the coating film of the said radiation sensitive resin composition by alkaline solution (3).

[Contact operation]
Next, a method of bringing the alkaline solution (1) into contact with the prepattern will be described.

  As an alkaline solution (1), the same thing as the alkaline solution (3) used at the said image development process is mentioned, for example.

  As a first method of bringing the alkaline solution (1) into contact with the pre-pattern, a method of forming the pre-pattern as described above and applying the alkaline solution (1) to the pre-pattern may be mentioned.

<Heating process (A)>
This step is a step of heating the pre-pattern in contact with the alkaline solution (1). The functional group possessed by the polymer [a] contained in the radiation sensitive resin composition in the portion where the pre-pattern and the alkaline solution (1) are in contact in the contact step (A) and the heating step (A). The solubility in water or alkaline solution (2) changes. Specifically, when this functional group is a lactone ring group, a carbonate ring group or a sultone ring group, the ring is opened to form an acidic group, whereby the solubility in water or an alkaline solution (2) is obtained. Changes. That is, the [a] polymer becomes soluble in water or an alkaline solution (2). Therefore, in this step, as shown in FIG. 1C, the solubility change area 4 is formed in the portion where the pre-pattern 2 and the alkaline solution 3 are in contact.

  The heating can be performed according to a known baking method. The heating temperature is usually 60 ° C. or more, preferably 70 ° C. or more, and more preferably 80 ° C. or more. On the other hand, the heating temperature is usually 140 ° C. or less, preferably 130 ° C. or less, more preferably 120 ° C. or less. If the heating temperature is in the above range, the solubility of the functional group in water or an alkaline solution (2) can be efficiently changed.

<Washing step (A)>
This step is a step of washing the heated pre-pattern with water or an alkaline solution (2). In this step, as shown in FIG. 1D, the solubility change region 4 formed in the pre-pattern 2 is removed by washing, and the pre-pattern 2 is slimmed.

  Examples of the alkaline solution (2) include the same as the alkaline solution (3) used in the above-mentioned development step.

  In a preferred embodiment, water is used in the washing step (A). In this case, the use of chemicals can be avoided, which is advantageous in terms of environment and ease of implementation.

  In another preferred embodiment, the alkaline solution (2) is used in the washing step (A), and this alkaline solution (2) is the same as the alkaline solution (1). The use of the same alkaline solution (2) as the alkaline solution (1) facilitates the implementation of the pattern formation method.

  The cleaning can be performed in the same manner as the conventional resist pattern development method.

  As described above, in the pattern formation method, the solubility in water or the alkaline solution (2) changes in the portion where the prepattern comes in contact with the alkaline solution (1) and slimming of the prepattern (fine pattern exceeding the wavelength limit) Formation) can be achieved. According to the pattern formation method, it is the functional group whose solubility in water or alkaline solution (2) changes that contributes to slimming, and the site other than this functional group of the polymer contained in the radiation sensitive resin composition Since basically does not affect slimming, it is possible to select sites other than this functional group relatively freely. As a result, the dependence of the slimming amount on the type of resist material is reduced. In addition, in the obtained pattern, there is also an effect that LWR is reduced.

<Second pattern formation method>
Hereinafter, the second pattern formation method of the present invention will be described. The pattern forming method includes an exposure step (B), a contact step (B), a heating step (B), and a cleaning step (B). Each step will be described below. In the first pattern formation method, an alkaline solution is brought into contact with the coated film (pre-pattern) after pattern formation, but in the second pattern formation method, the alkaline solution is applied to the coated film (patterned after exposure) before pattern formation. Contact By heating after bringing the coating solution in contact with the coating film before pattern formation into contact with the coating film prior to the formation of the pattern, the general development which is not heated after bringing the coating solution in contact with the coating film before the pattern formation As compared with the case of, it is possible to obtain a fine and small LWR pattern.

<Exposure process (B)>
This process is a process of exposing the coating film formed using the radiation sensitive resin composition.

  The radiation sensitive resin composition used in this step contains a polymer having a functional group whose solubility in water or alkaline solution (2) is changed by contact with an alkaline solution (1) and heating. The same radiation sensitive resin composition used in the first pattern formation method can be used. The functional group whose solubility is changed is preferably a lactone ring group, a carbonate ring group or a sultone ring group, and more preferably a lactone ring group. Preferably, the polymer further has an acid dissociable group, and the radiation sensitive resin composition further contains a radiation sensitive acid generator.

  The coating film can be formed by performing the resist film forming operation described in the resist film forming process of the first pattern forming method.

  The exposure operation of the coating film can be performed by the same operation as the exposure in the exposure step (A) of the first pattern formation method.

  After the exposure, post-exposure baking (PEB) is carried out, and in the exposed part of the resist film, the acid dissociable group of the polymer [a] polymer by the acid generated from the radiation-sensitive acid generator [b] by exposure. It is preferable to promote dissociation. The PEB causes a difference in the solubility of the exposed portion (exposed portion) and the non-exposed portion (unexposed portion) in the developer. The PEB temperature is usually 50 ° C. or more, preferably 80 ° C. or more, and is usually 180 ° C. or less, preferably 130 ° C. or less. The PEB time is usually 5 seconds or more, preferably 10 seconds or more, while it is usually 600 seconds or less, preferably 300 seconds or less.

<Contact process (B)>
This step is a step of bringing the alkaline solution (1) into contact with the exposed coating film. This step can be carried out by applying an alkaline solution (1) on the exposed coated film according to a known method. Thereby, what the alkaline solution (1) adhered to the surface of the exposed coating film is formed. Examples of the alkaline solution (1) include the same as the alkaline solution (1) used in the first pattern formation method.

<Heating process (B)>
This step is a step of heating the coating film brought into contact with the alkaline solution (1). The functional group of the polymer [a] contained in the radiation sensitive resin composition in the portion where the coating film and the alkaline solution (1) are in contact in the contact step (B) and the heating step (B). The solubility in water or alkaline solution (2) changes. Specifically, when this functional group is a lactone ring group, a carbonate ring group or a sultone ring group, the ring is opened to form an acidic group, whereby the solubility in water or an alkaline solution (2) is obtained. Changes. That is, the [a] polymer becomes soluble in water or an alkaline solution (2). Therefore, in this step, the solubility change area is formed in the portion where the coating film and the alkaline solution are in contact.

  The heating can be performed according to a known baking method. The heating temperature is usually 50 ° C. or higher, preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and still more preferably 75 ° C. On the other hand, the heating temperature is usually 140 ° C. or less, preferably 120 ° C. or less, more preferably 100 ° C. or less, still more preferably 90 ° C. or less, particularly preferably 85 ° C. or less. The heating time is usually 10 seconds or more, preferably 20 seconds or more, more preferably 30 seconds or more, and still more preferably 40 seconds or more. On the other hand, the heating time is usually 600 seconds or less, preferably 300 seconds or less, more preferably 180 seconds or less, still more preferably 120 seconds or less, and particularly preferably 90 seconds or less. If the heating temperature is in the above range, the solubility of the functional group in water or an alkaline solution (2) can be efficiently changed.

<Washing process (B)>
This step is a step of washing the heated coating film with water or an alkaline solution (2). This process can be performed by the same operation as the cleaning process (A) of the first pattern formation method. In this step, the solubility change area formed on the coating film is removed by washing to form a pattern. Since the solubility of the coating film in water or the alkaline solution (2) is changed by the heating step (B), the pattern obtained after the cleaning step (B) is a normal pattern in which the coating film before pattern formation is not heated. It becomes finer than in the case of development. That is, it becomes a fine one exceeding the wavelength limit.

  Hereinafter, the embodiments of the present invention will be more specifically described by way of examples. However, the present invention is not at all limited to these examples.

[1] Synthesis of Polymer (A-1) The measurement and evaluation of the physical properties of the polymer (A-1) were performed in the following manner.

(1) Mw and Mn
The Mw and Mn of the polymer (A-1) were measured using a GPC column (two “G2000HXL” by Tosoh Corp., one “G3000HXL”, one “G4000HXL”) under the following conditions.
Column temperature: 40 ° C
Elution solvent: tetrahydrofuran (Wako Pure Chemical Industries, Ltd.)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential Refractometer Standard substance: Monodispersed polystyrene

⁽²⁾ 13 C-NMR analysis of ¹³ C-NMR analysis of the polymer (A-1) was performed using "JNM-EX270" of JEOL.

  Hereinafter, the synthesis of the polymer (A-1) will be described. Monomers [compounds (M-1) to (M-4)] used for the synthesis of the polymer (A-1) are shown below.

<Synthesis of Polymer (A-1)>
First, as a monomer, 35 mol% of the above compound (M-1), 25 mol% of the compound (M-2), 10 mol% of the compound (M-3), 30 mol% of (M-4) and an initiator (2) A monomer solution in which 2,2'-azobisisobutyronitrile (AIBN) was dissolved in 30 g of methyl ethyl ketone was prepared. The total amount of monomers at the time of preparation was adjusted to 30 g. The mol% of each monomer represents mol% with respect to the total amount of monomers, and the use ratio of the initiator was 5 mol% with respect to the total amount of the monomer and the initiator.

  Meanwhile, 30 g of ethyl methyl ketone was added to a 500 mL three-necked flask equipped with a thermometer and a dropping funnel, and nitrogen purge was performed for 30 minutes. Thereafter, the inside of the flask was heated to 80 ° C. while being stirred by a magnetic stirrer.

Then, the above monomer solution was dropped into the flask using a dropping funnel over 3 hours. After dripping, it was aged for 3 hours, and then cooled to 30 ° C. or lower to obtain a polymer solution. The polymerization solution was poured into 600 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was slurried twice with 120 g portions of methanol, washed, filtered, and dried at 50 ° C. for 17 hours to obtain a white powdery polymer (A-1) (23 .3 g, yield: 77.7%). As a result of ¹³ C-NMR analysis, the content ratio (mol%) of the structural units derived from the compounds (M-1) to (M-4) in the polymer (A-1) is 36.7: 22.3: 9.8: 31.2 (mol%). Moreover, Mw of the polymer (A-1) was 6,500, and Mw / Mn was 1.4.

[2] Preparation of radiation sensitive resin composition 100 parts by mass of polymer (A-1), 12 parts by mass of radiation sensitive acid generator (B-1), 0.64 parts of acid diffusion control agent (C-1) Radiation-sensitive resin by mixing 1 part, and 1980 parts by weight of solvent (D-1), 849 parts by weight of (D-2) and 30 parts by weight of (D-3), and filtering through a membrane filter with a pore size of 0.2 μm Composition (E-1) was prepared. In addition, the used acid generator (B-1), acid diffusion control agent (C-1), and solvent (D-1)-(D-3) are as follows.

Radiation-sensitive acid generator
(B-1): compounds shown below

<Acid diffusion control agent>
(C-1): compounds shown below

<Solvent>
(D-1): Propylene glycol monomethyl ether acetate (D-2): cyclohexanone (D-3): γ-butyrolactone

[3] Formation of Resist Pattern Using Radiation-Sensitive Resin Composition For the radiation-sensitive resin composition (E-1), a silicon wafer on which a 90 nm line-and-space pattern was formed was produced as follows. did. A lower antireflective film ("ARC 29A" from Brewer Science, Inc.) is spin-coated on an 8-inch silicon wafer using "CLEAN TRACK ACT 8" from Tokyo Electron Co., Ltd. to a film thickness of 77 nm. (205 ° C., 60 seconds) was performed to form a coating. On the formed coating film, a radiation sensitive resin composition solution was spin-coated using “CLEAN TRACK ACT 8”, and PB (100 ° C., 60 seconds) was performed to form a resist film with a film thickness of 100 nm. The resist film thus formed is passed through a mask pattern of 90 nm Line 180 nm Pitch using an ArF excimer laser exposure apparatus “NSR S306C” (illumination condition: NA 0.78, σ0 / σ1 = 0.93 / 0.62, Dipole) manufactured by Nikon Corporation. Exposed. After PEB (100 ° C., 60 seconds), development was carried out with a 2.38% by weight aqueous solution of tetramethylammonium hydroxide at 23 ° C. for 30 seconds. After washing with water, it was dried to form a positive resist pattern. At this time, the exposure amount at which a portion exposed through the mask pattern of 90 nm Line 180 nm Pitch forms a line with a line width of 90 nm was taken as the optimum exposure amount (Eop). In addition, the scanning electron microscope ("S-9380" of Hitachi High-Technologies company) was used for length measurement.

[4] Pattern refinement evaluation [Example 1]
2.38 mass% tetramethylammonium hydroxide aqueous solution is spin-coated using "CLEAN TRACK ACT 8" as a pattern refining agent on an 8-inch wafer on which a 90 nm line and space pattern is formed by the above method. did. After baking (80 ° C., 60 seconds), the substrate was rinsed with ultrapure water and dried to produce an evaluation substrate.

Example 2
2.38 mass% tetramethylammonium hydroxide aqueous solution is spin-coated using "CLEAN TRACK ACT 8" as a pattern refining agent on an 8-inch wafer on which a 90 nm line and space pattern is formed by the above method. did. After baking (100 ° C., 60 seconds), the substrate was rinsed with ultrapure water and dried to prepare an evaluation substrate.

[Example 3]
2.38 mass% tetramethylammonium hydroxide aqueous solution is spin-coated using "CLEAN TRACK ACT 8" as a pattern refining agent on an 8-inch wafer on which a 90 nm line and space pattern is formed by the above method. did. After baking (120 ° C., 60 seconds), the substrate was rinsed with ultrapure water and dried to prepare an evaluation substrate.

Example 4
A lower antireflective film ("ARC 29A" from Brewer Science, Inc.) is spin-coated on an 8-inch silicon wafer using "CLEAN TRACK ACT 8" from Tokyo Electron Co., Ltd. to a film thickness of 77 nm. (205 ° C., 60 seconds) was performed to form a coating. On the formed coating film, a radiation sensitive resin composition (E-1) solution is spin-coated using “CLEAN TRACK ACT 8”, and PB (100 ° C., 60 seconds) is applied to form a coating film having a film thickness of 100 nm. (Resist film) was formed. The coating film thus formed is exposed through a mask pattern of 90 nm Line 180 nm Pitch using an ArF excimer laser exposure apparatus “NSR S306C” (illumination condition: NA 0.78, σ 0 / σ 1 = 0.93 / 0.62, Dipole) manufactured by Nikon Corporation. It exposed by the said optimal exposure amount. After PEB (100 ° C., 60 seconds), a 2.38 mass% tetramethylammonium hydroxide aqueous solution was brought into contact with the exposed coating film at 23 ° C. for 30 seconds. Bake at 80 ° C. for 60 seconds with a 2.38% by mass tetramethylammonium hydroxide aqueous solution adhering to the surface of the coated film, rinse with ultrapure water, and dry to form a positive resist pattern did.

Comparative Example 1
A mixed solution of 0.05 parts by mass of vinyl sulfonic acid and 99.95 parts by mass of 4-methyl-2-pentanol as a pattern refining composition is formed on an 8-inch wafer on which a 90 nm line and space pattern is formed. Spin-coated using "CLEAN TRACK ACT 8". After baking (80 ° C., 60 seconds), the plate was cooled for 30 seconds with a 23 ° C. cooling plate. Next, the substrate was washed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 23 ° C. for 20 seconds, rinsed with ultrapure water, and dried to prepare an evaluation substrate.

Comparative Example 2
In the case where the pattern refining composition was not used, only the baking and developing processes were performed to prepare an evaluation substrate.

[Line width refinement degree (%)]
In the above Examples and Comparative Examples, the dimensions of the resist pattern before and after the refinement treatment were measured by a scanning electron microscope "S-9380", and the line width refinement degree was calculated by the following formula (1).
Line width refinement degree (%) = (line width before treatment (nm) -line width after treatment (nm)) / (line width before treatment (nm)) × 100 (1)

[LWR (Line Width Roughness) (nm)]
In the said Example and comparative example, the dimension of the resist pattern after refinement processing was measured in LWR measurement mode of the said scanning electron microscope "S-9380." The measurement was made at 32 places at regular intervals between the line pattern vertical axes (measurement range: 1000 nm), and 3σ values of the line widths of the 32 places were measured. This was measured with ten different line patterns, and the average value of these ten 3σ values was taken as LWR. The evaluation results are shown in Table 1.
LWR = {1st line pattern (3σ value) + 2nd line pattern (3σ value) +
.... 10th line pattern (3σ value)} ÷ 10

  From Table 1, it can be seen that according to the pattern formation method of the example, a pattern having a smaller line width and a smaller LWR can be formed as compared to the case where the miniaturization process is not performed.

  According to the first pattern formation method of the present invention, the dependence of the slimming amount on the type of resist material is small. In addition, LWR is reduced in the obtained pattern. According to the second pattern formation method of the present invention, a fine pattern having a small LWR and exceeding the wavelength limit can be formed regardless of the type of the resist material. Therefore, these pattern formation methods can be suitably used for pattern formation in the semiconductor processing field etc. which is expected to be further miniaturized in the future.

1 substrate 2 prepattern 3 alkaline solution 4 solubility change area

Claims (8)

Bringing a first alkaline solution into contact with a pre-pattern formed using the radiation sensitive resin composition;
Heating the prepattern brought into contact with the first alkaline solution;
Washing the heated pre-pattern with water or a second alkaline solution,
The radiation sensitive resin composition contains a polymer having a functional group whose solubility in the water or the second alkaline solution is changed by contact with the first alkaline solution and heating .
The pattern formation method whose said 1st alkaline solution is TMAH aqueous solution .   The pattern formation method according to claim 1, wherein the functional group whose solubility is changed is a lactone ring group, a carbonate ring group or a sultone ring group.   The pattern formation method according to claim 2, wherein the functional group whose solubility changes is a lactone ring group.   The pattern formation method according to claim 1, wherein the polymer further has an acid dissociable group, and the radiation sensitive resin composition further contains a radiation sensitive acid generator.   The said pre-pattern is a positive type pre-pattern formed by developing the coating film of the said radiation sensitive resin composition with a 3rd alkaline solution, The claim is any one of Claim 1 to 4 Pattern formation method.   The pattern formation method according to any one of claims 1 to 5, wherein the heating step is performed at 60 ° C to 140 ° C.   The pattern formation method according to any one of claims 1 to 6, wherein water is used in the cleaning step.   The pattern formation method according to any one of claims 1 to 6, wherein a second alkaline solution is used in the cleaning step, and the second alkaline solution is the same as the first alkaline solution.

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