KR20130035941A

KR20130035941A - Upper layer film forming composition for liquid immersion and method of forming resist pattern

Info

Publication number: KR20130035941A
Application number: KR1020120108600A
Authority: KR
Inventors: 다카히로 하야마; 가즈노리 구사비라키; 기요시 다나카; 모토유키 시마
Original assignee: 제이에스알 가부시끼가이샤
Priority date: 2011-09-30
Filing date: 2012-09-28
Publication date: 2013-04-09

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to provide a composition for forming an immersion upper layer film and a method of forming a resist pattern capable of achieving a balanced balance between peeling resistance and exposure margin while satisfying properties for water repellency, solvent resistance and solubility.
Means for Solving the Invention
[A1] A polymer having structural unit (I-1) containing a group represented by the following formula (i), [A2] A polymer different from the above [A1] polymer, and a liquid immersion upper layer film containing [B] solvent Composition. R <^1> is a C1-C20 (n + 1) valent hydrocarbon group in following formula (i). n is an integer of 1 to 3; It is preferable that the backward contact angle with water in the film-forming state of the [A2] polymer is larger than the [A1] polymer.

Description

UPPER LAYER FILM FORMING COMPOSITION FOR LIQUID IMMERSION AND METHOD OF FORMING RESIST PATTERN}

The present invention relates to a composition for forming an immersion upper layer film and a method for forming a resist pattern.

BACKGROUND In the manufacture of semiconductor devices, microfabrication by lithography using a chemically amplified resist composition has been conventionally performed. Generally, the pattern formation method used in this microfabrication includes the steps of forming a resist film on a substrate, an exposure step of irradiating radiation such as ultraviolet rays to the resist film through a mask, a developing step of developing the exposed resist film, and a resist obtained. The process of etching a board | substrate using a pattern as a protective film is included.

In this pattern forming method, the acid generated in the exposed portion detaches the acid dissociable group of the polymer in the resist composition, and the polarity is changed to change the dissolution rate of the developer in the exposed portion and the unexposed portion, thereby forming the pattern.

As a method of forming a finer resist pattern in recent years, the use of the liquid immersion exposure method which exposes between a lens and a resist film with liquid immersion media, such as pure water and a fluorine-type inert liquid, for example, is expanding. According to this immersion exposure method, the numerical aperture (NA) of the lens can be enlarged, and even when the NA is enlarged, the depth of focus is less likely to decrease, and further, high resolution can be obtained.

In the pattern formation method by this immersion exposure method, in order to prevent the resist film component from eluting to the immersion medium, the immersion upper layer film used as a protective film is normally provided on the resist film. The liquid immersion upper layer film is dissolved and removed by high water solubility in a developing solution after suppressing elution of a resist film component in an exposure process by its water repellency, and then developing in a developing process.

In the liquid immersion upper layer film-forming composition capable of forming such a liquid immersion upper layer film, in addition to the water repellency, solvent resistance and solubility, the substrate at the portion where the liquid immersion upper layer film is directly in contact with the substrate at the periphery of the liquid immersion upper layer film Improvement in peeling resistance and exposure margin from is required.

In response to this demand, in a technique for improving peeling resistance, a liquid immersion upper layer film containing a carboxylic acid resin is disclosed (see Japanese Patent Laid-Open No. 2009-205132). However, in the immersion upper layer film containing the carboxylic acid resin, the peeling resistance from the substrate is improved, but the exposure margin decreases, making it difficult to form a desired resist pattern, so that the peeling resistance and the exposure margin can be balanced in a balanced manner. none.

Japanese Patent Publication No. 2009-205132

The present invention has been made on the basis of the above circumstances, and its object is to satisfy the characteristics of water repellency, solvent resistance, and solubility, and to provide a composition and resist for forming an immersion upper layer film which can balance both peel resistance and exposure margin in balance. It is to provide a pattern forming method.

The invention made to solve the above problems is

[A1] A polymer having a structural unit (I-1) containing a group represented by the following general formula (i) (hereinafter also referred to as "[A1] polymer"),

[A2] A polymer different from the above [A1] polymer (hereinafter also referred to as "[A2] polymer"), and

[B] solvent

It is a composition for liquid immersion upper layer film containing.

(In formula, R <^1> is a C1-C20 (n + 1) valent hydrocarbon group. N is an integer of 1-3.)

The liquid immersion upper layer film-forming composition can balance both peel resistance and exposure margin by containing a [A1] polymer having a hydroxyl group, and can further improve water repellency and solvent resistance by containing a [A2] polymer. . As a result, the liquid immersion upper layer film-forming composition can form a liquid immersion upper layer film that is compatible in balance between peeling resistance and exposure margin while satisfying properties such as water repellency.

It is preferable that the backward contact angle with water in the film-forming state of the [A2] polymer is larger than the [A1] polymer. Due to the fact that the receding contact angle with water in the film-forming state of the polymer [A2] is larger than that of the polymer [A1], the immersion upper layer film-forming composition has a water repellency for water which is usually used as an immersion medium and a resist film for water. The solvent resistance of a component can be improved more.

It is preferable that the said structural unit (I-1) is a structural unit represented by following formula (1).

(In formula 1, R <^1> and n are synonymous with the said Formula (i). R <^2> is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group.)

By the structural unit (I-1) being the said specific structural unit, the said liquid immersion upper layer film forming composition can balance both peeling resistance and exposure margin more balanced.

[A2] It is preferable that the polymer has at least one structural unit (II-1) selected from the group consisting of a structural unit containing a group represented by the following formula (2) and a structural unit containing a group represented by the following formula (3). .

In Formula 2, R ³ and R ⁴ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a fluorinated alkyl group having 1 to 4 carbon atoms, provided that at least one of R ³ and R ⁴ is a fluorinated alkyl group having 1 to 4 carbon atoms. In formula (3), R ⁵ is a fluorinated alkyl group having 1 to 20 carbon atoms)

When the polymer (A2) has the specific structural unit, the immersion upper layer film-forming composition can further improve water repellency and solvent resistance.

It is preferable that the polymer [A2] further has a structural unit (II-2) represented by the following general formula (4).

(In formula 4, R <^6> is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group. R <^7> is a C1-C12 monovalent fluorinated hydrocarbon group.)

[A1] The polymer is at least one structural unit (I-2) selected from the group consisting of a structural unit containing a group represented by the following formula (2 ') and a structural unit containing a group represented by the following formula (3'). It is preferable to have more).

(In formula (2 '), R <^3> and R <^4> is synonymous with said Formula (2).

In formula (3 '), R ⁵ is synonymous with formula (3) above)

When the polymer (A1) has the specific structural unit, the liquid immersion upper layer film-forming composition can further improve water repellency and solvent resistance.

It is preferable that the polymer [A1] further has a structural unit (I-3) containing a sulfo group. When the polymer (A1) further has the specific structural unit, the immersion upper layer film-forming composition can further improve peel resistance.

The solvent (B) preferably contains an ether solvent. When the solvent (B) contains an ether solvent, the composition for forming the immersion upper layer film is not only excellent in coating property, but can also reduce intermixing between the resist film and the immersion upper layer film.

The resist pattern forming method of the present invention,

(1) forming a resist film on a substrate using a resist composition,

(2) forming a liquid immersion upper layer film on the resist film using the composition for forming a liquid immersion upper layer film,

(3) exposing the resist film and the liquid immersion upper layer film through a liquid immersion medium, and

(4) developing the exposed resist film and the liquid immersion upper layer film

Respectively.

Since the resist pattern forming method has the above specific process, the resist pattern forming method can balance the peel resistance and the exposure margin while satisfying the properties for water repellency, solvent resistance and solubility.

In addition, the receding contact angle between the polymer [A1] and the water [A2] in the film formation state is formed by spin coating a solution containing each polymer on a silicon wafer to form a film, and draining water from the needle on the obtained film. 25 μl of water droplets were formed, and once the needle was removed from the water drop, the needle was inserted into the water drop again, and the retracting contact angle was made at a frequency of once per second while sucking the water drop for 90 seconds by the needle at a rate of 10 μl / min. After the measurement, the measured value was stabilized and averaged for 20 seconds.

According to the composition for forming a liquid immersion upper layer film and the resist pattern forming method of the present invention, it is possible to balance the peeling resistance and the exposure margin while satisfying the properties of water repellency, solvent resistance and solubility. Therefore, the said immersion upper layer film forming composition and the resist pattern formation method can be applied suitably to the manufacturing process of the semiconductor device which further refine | miniaturizes a resist pattern.

The composition for immersion upper layer film formation of this invention contains a [A1] polymer, a [A2] polymer, and a [B] solvent. In addition, the composition may contain any component so long as the effects of the present invention are not impaired. Each component will be described in detail below.

<[A1] Polymer>

The polymer [A1] is a polymer having a structural unit (I-1). In addition, the polymer [A1] may have a structural unit (I-2). In addition, the polymer [A1] may have a structural unit (I-3). In addition, the polymer [A1] may have other structural units. In addition, the polymer [A1] may have two or more kinds of structural units.

[Structural Unit (I-1)]

Structural unit (I-1) is a structural unit containing the group represented by the said general formula (i). [A1] The polymer has a structural unit containing a group represented by the formula (i), whereby the liquid immersion upper layer film-forming composition satisfies the characteristics of water repellency, solvent resistance and solubility, while providing peel resistance and exposure margin. A liquid immersion upper layer film can be formed in a balanced manner.

In said general formula (i), R <^1> is a C1-C20 (n + 1) valent hydrocarbon group. n is an integer of 1 to 3; n is preferably 1 or 2.

As a C1-C20 (n + 1) valent hydrocarbon group represented by said R <^1> , For example, a C1-C20 linear or branched (n + 1) valent linear hydrocarbon group, C3-C20 (n + 1) valent alicyclic hydrocarbon group, a C6-C20 (n + 1) valent aromatic hydrocarbon group, or (n + 1) valent group which combined 2 or more types of these groups, etc. are mentioned.

Examples of the linear or branched (n + 1) valent linear hydrocarbon group having 1 to 20 carbon atoms include groups obtained by removing n hydrogen atoms from a linear or branched alkyl group having 1 to 20 carbon atoms. have.

Examples of the linear or branched alkyl group having 1 to 20 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group etc. are mentioned.

As said C3-C20 (n + 1) valent alicyclic hydrocarbon group, group etc. which removed n hydrogen atoms from the C3-C20 monovalent alicyclic hydrocarbon group are mentioned, for example.

As said C3-C20 monovalent alicyclic hydrocarbon group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, etc. are mentioned, for example.

As said C6-C20 (n + 1) valent aromatic hydrocarbon group, group which removed n hydrogen atoms from the C6-C20 monovalent aromatic hydrocarbon group, etc. are mentioned, for example.

As said C6-C20 monovalent aromatic hydrocarbon group, a phenyl group, a tolyl group, a naphthyl group, etc. are mentioned, for example.

Examples of the (n + 1) valent group in which two or more of these groups are combined include, for example, the linear or branched (n + 1) valent hydrocarbon group having 1 to 20 carbon atoms, and the (n +) having 3 to 20 carbon atoms. 1) A valent alicyclic hydrocarbon group and the group which combined 2 or more types of groups illustrated as said C6-C20 (n + 1) valent aromatic hydrocarbon group, etc. are mentioned.

It is preferable that a structural unit (I-1) is a structural unit represented by the said General formula (1). When the polymer [A1] has a structural unit represented by the above formula (1), the peeling resistance and the exposure margin can be more balanced.

In said Formula (1), R <^1> and n are synonymous with the said Formula (i). R ² is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group.

The hydrocarbon group represented by R ¹ is preferably a hydrocarbon group having 1 to 10 carbon atoms, a straight or branched chain hydrocarbon group having 1 to 5 carbon atoms, an alicyclic hydrocarbon group having 3 to 8 carbon atoms, or two or more of these groups. Groups combined are more preferred.

As the structural unit (I-1), a structural unit represented by the following formula is particularly preferable.

In the polymer [A1], the content of the structural unit (I-1) relative to the total structural units is preferably 0.1 mol% or more and 50 mol% or less, and more preferably 0.5 mol% or more and 30 mol% or less. By making content rate of a structural unit (I-1) into the said specific range, peeling resistance and exposure margin can be made to balance effectively effectively.

[Structural Unit (I-2)]

The structural unit (I-2) is at least one structural unit selected from the group consisting of a structural unit containing a group represented by the formula (2 ') and a structural unit containing a group represented by the formula (3'). to be. When the polymer (A1) has the structural unit (I-2), the immersion upper layer film-forming composition can further improve water repellency and solvent resistance.

In said general formula (2 '), R <^3> and R <^4> is a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 fluorinated alkyl group. Provided that at least one of R ³ and R ⁴ is a fluorinated alkyl group having 1 to 4 carbon atoms. In general formula (3 '), R <^5> is a C1-C20 fluorinated alkyl group.

The alkyl group having 1 to 4 carbon atoms represented by R ³ and R ⁴ may be either linear or branched, and examples thereof include methyl group, ethyl group, n-propyl group and i-propyl group.

The C1-C4 fluorinated alkyl group represented by said R <^3> and R <^4> is group in which at least 1 of the hydrogen atom which the C1-C4 alkyl group has is substituted by the fluorine atom. As said C1-C4 alkyl group, group illustrated as an C1-C4 alkyl group represented by said R <^3> and R <^4> is applicable, for example.

The fluorinated alkyl group having 1 to 20 carbon atoms represented by R ⁵ is a group in which at least one hydrogen atom of the alkyl group having 1 to 20 carbon atoms is substituted with a fluorine atom. The alkyl group having 1 to 20 carbon atoms may be either linear or branched, and examples thereof include methyl group, ethyl group, n-propyl group and i-propyl group.

As a C1-C4 fluorinated alkyl group represented by said R <^3> and R <^4> , a trifluoromethyl group is preferable.

As a structural unit containing the group represented by the said General formula (2 '), and a structural unit (I-2) containing the group represented by the said General formula (3'), respectively, are structural units represented with the following general formula (2'-1) And structural units represented by the following general formula (3'-1).

In said Formula (2'-1) and (3'-1), R <^8> and R <^10> is respectively independently a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group. In formula (2'-1), R ⁹ is a divalent linking group. In formula (3'-1), R ¹¹ is a divalent linking group. R ⁵ is synonymous with formula (3).

Examples of the divalent linking group represented by R ⁹ include a linear or branched divalent linear hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a combination thereof. Can be mentioned.

Examples of the linear or branched divalent linear hydrocarbon group having 1 to 6 carbon atoms include methylene group, ethylene group, 1,3-propylene group, 1,2-propylene group, 1,1-propylene group, 2 , 2-propylene group, tetramethylene group, pentamethylene group, hexamethylene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2-propylene group , 1-methyl-1,4-butylene group, 2-methyl-1,4-butylene group, and the like.

As said C4-C12 divalent alicyclic hydrocarbon group, For example, Monocyclic hydrocarbon groups, such as a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cyclooctylene group; Polycyclic hydrocarbon groups, such as a norbornylene group and an adamantylene group, etc. are mentioned.

As the divalent linking group represented by R ¹¹ , for example, a group exemplified as the divalent linking group represented by R ⁹ can be applied.

As a structural unit represented by the said General formula (2'-1), the structural unit represented by following General formula (2'-1-1)-(2'-1-8), etc. are mentioned, for example.

R <^8> is synonymous with the said General formula (2'-1) in the said General formula (2'-1-1)-(2'-1-8). Among these, structural units represented by the formulas (2'-1-4) and (2'-1-8) are preferable.

As a structural unit represented by the said General formula (3'-1), the structural unit represented by following General formula (3'-1-1)-(3'-1-3), etc. are mentioned, for example.

R <^10> is synonymous with the said General formula (3'-1) in the said General formula (3'-1-1)-(3'-1-3). Among these, the structural unit represented by general formula (3'-1-1) is preferable.

In the polymer [A1], the content of the structural unit (I-2) relative to the total structural units is preferably 20 mol% or more and 98 mol% or less, more preferably 35 mol% or more and 95 mol% or less, and 50 mol% 90 mol% or more is more preferable. By making the content rate of a structural unit (I-2) into the said specific range, water repellency and solvent resistance can be improved effectively.

[Structural Unit (I-3)]

Structural unit (I-3) is a structural unit containing a sulfo group. When the polymer (A1) further has the specific structural unit (I-3), the immersion upper layer film-forming composition can further improve peel resistance.

As structural unit (I-3), the structural unit represented by following formula (5), etc. are mentioned, for example.

In said Formula (5), R <^12> is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group. R ¹³ is a single bond, an oxygen atom, a sulfur atom, a straight or branched divalent linear hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, and a divalent aromatic hydrocarbon having 6 to 12 carbon atoms. Group or -C (= O) -XY- group. X is an oxygen atom, a sulfur atom or an NH group. Y is a single bond, a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms.

Examples of the linear or branched divalent linear hydrocarbon group having 1 to 6 carbon atoms represented by R ¹³ and Y include, for example, methylene group, ethylene group, 1,3-propylene group, 1,2-propylene group, 1 , 1-propylene group, 2,2-propylene group, tetramethylene group, pentamethylene group, hexamethylene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl -1,2-propylene group, 1-methyl-1,4-butylene group, 2-methyl-1,4-butylene group, etc. are mentioned.

As a C4-C12 bivalent alicyclic hydrocarbon group represented by said R <^13> and Y, For example, Monocyclic hydrocarbon groups, such as a cyclobutylene group, a cyclopentylene group, a cyclooctylene group; Polycyclic hydrocarbon groups, such as a norbornylene group and an adamantylene group, etc. are mentioned.

As a C6-C12 bivalent aromatic hydrocarbon group represented by said R <^13> and Y, arylene groups, such as a phenylene group and a tolylene group, etc. are mentioned, for example. In addition, the alicyclic hydrocarbon group and the aromatic hydrocarbon group need not be composed of only a ring structure, and may include a chain structure in a part thereof.

As said structural unit (I-3), the structural unit represented by following General formula (5-1)-(5-5) is preferable.

In the formulas (5-1) to (5-5), R ¹² has the same meaning as in formula (5). Among these, (5-1) and (5-5) are preferable.

In the polymer [A1], the content of the structural unit (I-3) relative to the total structural units is preferably 0.1 mol% or more and 20 mol% or less, and more preferably 1 mol% or more and 15 mol% or less. By making content rate of a structural unit (I-3) into the said specific range, peeling resistance can be raised effectively.

[Other structural units]

[A1] The polymer may contain other structural units other than the structural units (I-1) to (I-3) in a range that does not impair the effects of the present invention.

70 A or less is preferable, as for the backward contact angle with water in the film-forming state of [A1] polymer, 68 degrees or less are more preferable, and 63 degrees or less are preferable.

<[A2] polymer>

The polymer [A2] is a polymer different from the polymer [A1]. The polymer [A2] is not particularly limited as long as it is different from the polymer [A1], but it is preferable that the receding contact angle with water in the film-forming state of the polymer [A2] is larger than that of the polymer [A1]. In this case, as for [A2] polymer, it is more preferable that the difference of the said receding contact angle is 3 degrees or more, It is still more preferable that it is 5 degrees or more, It is especially preferable that it is 10 degrees or more.

Moreover, 73 degrees or more are preferable, as for the backward contact angle with water in the film-forming state of [A2] polymer, 75 degrees or more are more preferable, 80 degrees or more are more preferable.

When the polymer (A2) is the polymer having the above constitution, the immersion upper layer film-forming composition can further improve the water repellency of water commonly used as the immersion medium and the solvent resistance of the resist film component to the water.

It is preferable that this [A2] polymer is a polymer which has a structural unit (II-1). In addition, the polymer [A2] may have a structural unit (II-2). In addition, the polymer [A2] may have other structural units. In addition, the polymer [A2] may have two or more kinds of structural units.

[Structural unit (II-1)]

Structural unit (II-1) is at least 1 sort (s) of structural unit chosen from the group which consists of a structural unit containing the group represented by the said Formula (2), and the structural unit containing the group represented by the said Formula (3). When the polymer (A2) has the specific structural unit (II-1), the immersion upper layer film-forming composition can further improve water repellency and solvent resistance. In addition, the structural unit containing the group represented by the said Formula (2) and the structural unit containing the group represented by the said Formula (3) are respectively represented by the said Formula (2 ') in the structural unit (I-2) mentioned above. It is the same as the structural unit containing and the structural unit containing the group represented by the said General formula (3 ').

In the polymer [A2], the content of the structural unit (II-1) relative to the total structural units is preferably 5 mol% or more and 100 mol% or less, and more preferably 20 mol% or more and 99 mol% or less. By making the content rate of a structural unit (II-1) into the said specific range, water repellency and solvent resistance can be improved effectively.

[Structural Unit (II-2)]

Structural unit (II-2) is a structural unit represented by the said Formula (4). When the polymer (A2) has the specific structural unit, the immersion upper layer film-forming composition can further improve water repellency and solvent resistance.

In said Formula (4), R <^6> is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group. R ⁷ is a C 1-12 monovalent fluorinated hydrocarbon group.

The monovalent fluorinated hydrocarbon group having 1 to 12 carbon atoms represented by R ⁷ is a group in which at least one hydrogen atom of the monovalent hydrocarbon group having 1 to 12 carbon atoms is substituted with a fluorine atom.

As said C1-C12 monovalent hydrocarbon group, For example, a C1-C12 linear or branched alkyl group, a C3-C12 monovalent alicyclic hydrocarbon group, or the monovalent which combined two or more types of these groups And the like can be mentioned.

Examples of the linear or branched alkyl group having 1 to 12 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group etc. are mentioned.

As said C3-C12 monovalent alicyclic hydrocarbon group, a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, etc. are mentioned, for example.

As structural unit (II-2), the structural unit represented by following General formula (4-1)-(4-6) is preferable.

In said formula, R <^6> is synonymous with general formula (4).

In the polymer [A2], the content of the structural unit (II-2) relative to the entire structural unit is preferably 1 mol% or more and 90 mol% or less, and more preferably 10 mol% or more and 80 mol% or less. By making the content rate of a structural unit (II-2) into the said specific range, water repellency and solvent resistance can be improved effectively.

[Other structural units]

[A2] The polymer may contain other structural units other than the structural units (II-1) and (II-2) within a range that does not impair the effects of the present invention. As said other structural unit, the structural unit containing a carboxyl group, the structural unit containing the sulfo group demonstrated as structural unit (I-3) in the polymer [A1], etc. are mentioned, for example.

[Structural Units Containing Carboxyl Groups]

As a structural unit containing a carboxyl group, the structural unit derived from (meth) acrylic acid, a crotonic acid, an angelic acid, a tiglic acid, etc. are mentioned, for example.

As for the content rate of the structural unit containing the said carboxyl group with respect to all the structural units in [A2] polymer, 0 mol% or more and 50 mol% or less are preferable, and 10 mol% or more and 30 mol% or less are more preferable. By making content rate of the structural unit containing the said carboxyl group into the said specific range, peeling resistance can be raised effectively.

[Structural Unit [I-3]]

In the polymer [A2], the content of the structural unit (I-3) relative to the total structural units is preferably 0.1 mol% or more and 20 mol% or less, and more preferably 1 mol% or more and 15 mol% or less. Peeling resistance can be raised effectively by making the content rate of a structural unit (I-3) into the said specific range in a polymer [A2].

As content of a polymer [A2], 0.5 mass part-4,000 mass parts are preferable with respect to 100 mass parts of [A1] polymer, and 1 mass part-2,000 mass parts are more preferable. By making content of a polymer (A2) into the said range, water repellency and solvent resistance can be improved effectively.

As a synthesis | combining method of said each polymer, the monomer corresponding to each predetermined structural unit can be synthesize | combined, for example by superposing | polymerizing in a suitable solvent using a radical polymerization initiator.

Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobis. (2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionitrile), 2,2-azobis Dimethyl isobutyrate etc. are mentioned. These initiators can be used alone or in combination of two or more.

It will not specifically limit, if it is solvent other than the solvent which inhibits superposition | polymerization (nitrobenzene which has a polymerization inhibitory effect, the mercapto compound which has a chain transfer effect, etc.). When superposing | polymerizing under a crosslinking agent and a crosslinking catalyst, the kind of solvent is not specifically limited. Examples of the polymerization solvent include alcohol solvents, ketone solvents, amide solvents, ester lactone solvents, nitrile solvents, mixed solvents thereof, and the like. These polymerization solvents can use together 1 type (s) or 2 or more types.

Each polymer obtained by the polymerization reaction can be recovered by liquid solution extraction and reprecipitation. In addition to the liquid liquid extraction and reprecipitation, the polymer may be recovered by removing the low molecular component by liquid separation, column operation, ultrafiltration, or the like.

The reaction temperature in these synthesis methods is suitably determined according to the monomer which provides each structural unit, the kind of polymerization initiator to be used, etc.

As a polystyrene conversion weight average molecular weight (Mw) by gel permeation chromatography (GPC) of each polymer, 1,000-100,000 are preferable and 3,000-50,000 are more preferable. When Mw of a polymer is less than 1,000, intermixing of an immersion upper layer film and a resist film may arise easily. On the other hand, when Mw exceeds 100,000, there exists a possibility that each polymer will become difficult to melt | dissolve in a solvent. Moreover, 1-5 are preferable and, as for ratio (Mw / Mn) of Mw with respect to the polystyrene conversion number average molecular weight (Mn) by GPC, 1-3 are more preferable.

In addition, Mw and Mn of this specification are the analysis conditions of flow rate 1.0mL / min, an elution solvent tetrahydrofuran, column temperature 40 degreeC using the GPC column (two G2000HXL, one G3000HXL, and one G4000HXL) manufactured by Tosoh. It measures by GPC which makes monodisperse polystyrene the standard.

<[B] solvent>

The solvent (B) is a solvent that uniformly dissolves each component such as the [A1] polymer and the [A2] polymer. Moreover, [B] solvent can also be used 1 type or in combination or 2 or more types.

Examples of the solvent (B) include alcohol solvents, ether solvents, hydrocarbon solvents, ketone solvents, ester solvents, water, and the like.

As said alcohol solvent, For example, monohydric alcohols, such as butanol, pentanol, and 4-methyl- 2-pentanol; Polyhydric alcohols, such as ethylene glycol and propylene glycol, etc. are mentioned.

As said ether solvent, alkyl of polyhydric alcohols, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, for example Ethers; Alkyl ether acetates of polyhydric alcohols such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate and diethylene glycol monoethyl ether acetate; Aliphatic ethers such as diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, diisoamyl ether, hexylmethyl ether, octylmethyl ether, cyclopentylmethyl ether, dicyclopentyl ether; Aliphatic-aromatic ethers such as anisole and phenylethyl ether; Cyclic ethers, such as tetrahydrofuran, tetrahydropyran, and dioxane, etc. are mentioned.

Examples of the hydrocarbon solvent include higher hydrocarbons such as decane, dodecene and undecane.

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-n-pentyl ketone, and ethyl- n-butyl ketone, methyl-n-hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione And acetonyl acetone, diacetone alcohol, acetophenone and the like.

Examples of the ester solvent include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-valerolactone, n-propyl acetate, iso-acetic acid acetate, n-butyl acetate and isoacetic acid iso. -Butyl, sec-butyl acetate, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl acetate Cyclohexyl, n-nonyl acetate, methyl acetoacetate, ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol acetate Mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol mono acetate Ethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, diacetate glycol, methoxytriglycol acetate, ethyl propionate, n-butyl propionate And iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate, dimethyl phthalate and diethyl phthalate.

Among these, an alcohol solvent, an ether solvent, and a hydrocarbon solvent are preferable, and an alcohol solvent and an ether solvent are more preferable. Among these, an ether solvent is more preferable from the viewpoint of reducing the coating amount by decreasing the viscosity of the obtained liquid immersion upper layer film-forming composition, and consequently reducing the cost.

Preferable alcohol solvents include monohydric alcohols, aliphatic ethers, cyclic ethers, alkyl ethers of polyhydric alcohols, and alkyl ether acetates of polyhydric alcohols as ether solvents. More preferred is a solvent comprising at least one of a dihydric alcohol and aliphatic ethers having 4 to 10 carbon atoms, and particularly preferred is a solvent containing 4-methyl-2-pentanol and diisoamyl ether. .

[B] When the solvent contains aliphatic ethers having 4 to 10 carbon atoms and aliphatic ethers having 4 to 10 alkyl chains, C4 to 10 monovalent alcohols and 4 to 10 alkyl atoms As a mixing ratio (mass) of aliphatic ethers which have a chain | strand, it is preferable that it is 1: 99-90: 10, It is more preferable that it is 2: 98-70: 30, It is still more preferable that it is 5: 95-60: 40, Particular preference is given to 10:90 to 50:50.

The liquid immersion upper layer film-forming composition may contain an optional component other than the polymer [A1], the polymer [A2] and the solvent [B] within a range that does not impair the effects of the present invention. Each arbitrary component can use together 1 type (s) or 2 or more types, respectively. In addition, the compounding quantity of arbitrary components can be suitably determined according to the objective.

As said arbitrary component, surfactant etc. are mentioned, for example. As said surfactant, all, for example, are brand names BM-1000, BM-1100 (above, BM Chemie), megaface F142D, copper F172, copper F173, copper F183 (above, Dai Nippon Ink Chemical Co., Ltd. make). Commercially available fluorine type surfactants, such as these, are mentioned. As content of the said surfactant, 5 mass parts or less are preferable with respect to 100 mass parts of [A] polymers.

The said liquid immersion upper layer film formation composition can be manufactured by mixing [A1] polymer, [A2] polymer, [B] solvent, etc. in a predetermined ratio.

The resist pattern forming method of the present invention

(1) forming a resist film on a substrate using a resist composition,

Respectively.

Since the resist pattern forming method has the above specific process, the resist pattern forming method can balance the peel resistance and the exposure margin while satisfying the properties of water repellency, solvent resistance and solubility. Hereinafter, each process is demonstrated.

[Step (1)]

This step is a step of forming a resist film on a substrate using a resist composition. As said board | substrate, a silicon wafer etc. are mentioned, for example.

Examples of the resist composition include a positive or negative chemically amplified resist composition containing an acid generator, a positive resist composition containing an alkali-soluble resin and a quinonediazide-based photosensitive agent, an alkali-soluble resin and a crosslinking agent. And negative resist compositions to be included. As the resist composition, a commercially available resist composition can also be used. As a formation method of a resist film, a coating method is preferable and can be apply | coated by well-known methods, such as a spin coating method, for example. In addition, when apply | coating a resist composition, the quantity of the resist composition to apply is adjusted so that the resist film formed may become a predetermined | prescribed film thickness. In addition, after apply | coating a resist composition on a board | substrate, you may perform prebaking (henceforth "PB") in order to volatilize a solvent.

[Step (2)]

This step is a step of forming an immersion upper layer film on the resist film by using the composition for forming an immersion upper layer film.

In this process, after apply | coating the said composition for liquid immersion upper layer film forming, for example, it is preferable to bake. Since the immersion medium and the resist film do not come into direct contact with this firing, the lithographic performance of the resist film is degraded due to the penetration of the immersion medium into the resist film, or the component exposed to the immersion medium from the resist film causes the The lens can be effectively prevented from being contaminated. As the method of forming the immersion upper layer film, a method similar to the method of forming the resist film can be adopted except that the immersion upper layer film forming composition is used instead of the resist composition.

[Step (3)]

This step is a step of exposing the resist film and the immersion upper layer film by irradiating radiation to the resist film and the immersion upper layer film via an immersion medium between the immersion upper layer film and the lens.

As the immersion medium, a liquid having a larger refractive index than air is usually used. It is preferable to use water specifically, and it is more preferable to use pure water. In the state where the immersion medium is interposed, that is, the immersion medium is filled between the lens and the immersion upper layer film, radiation is irradiated from the exposure apparatus to expose the resist film and the immersion upper layer film through a mask having a predetermined pattern.

Examples of the radiation include visible light; ultraviolet rays such as g-ray and i-ray; Far ultraviolet rays such as excimer laser light; X-rays; Electron beams; and the like. Among these, ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm) are preferable. In addition, irradiation conditions, such as a radiation dose, can be suitably set according to the resist composition, the composition for liquid immersion upper layer film, etc.

[Step (4)]

This step is a step of developing the exposed resist film and the liquid immersion upper layer film with a developer, and forming a resist pattern. Since the immersion upper layer film is formed from the composition for forming the immersion upper layer film, the immersion upper layer film can be easily removed by the developer, and a special step for removing the immersion upper layer film is not required.

Examples of the developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldi Ethylamine, dimethylethanolamine, triethanolamine, tetraalkylammonium hydroxides (e.g., tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc.), pyrrole, piperidine, choline, 1, Alkaline aqueous solution which melt | dissolved at least 1 sort (s) of alkaline compounds, such as 8-diazabicyclo- [5.4.0] -7-undecene and 1,5- diazabicyclo- [4.3.0] -5-nonane, is preferable, Among these, aqueous solutions of tetraalkylammonium hydroxides are more preferable. Moreover, an appropriate amount of water-soluble organic solvents, such as alcohol, such as methanol and ethanol, and surfactant can also be added to this developing solution, for example.

Moreover, in order to improve the resolution etc. of a resist film, it is preferable to bake before image development after exposure. Although baking temperature can be set suitably by the resist composition to be used, the composition for liquid immersion upper layer film, etc., 30-200 degreeC is preferable and 50-150 degreeC is more preferable.

[Example]

Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not restrict | limited to these Examples.

In addition, the receding contact angle with water in the film-forming state of the [A1] polymer and the [A2] polymer was measured by the following method.

After dissolving each polymer in propylene glycol monomethyl ether acetate, the solution was spin-coated on a silicon wafer, and PB was performed at 90 DEG C for 60 seconds to form an immersion upper layer film having a thickness of 30 nm. Thereafter, the wafer is set in a receding contact angle measuring device (DSA-10, manufactured by KRUS), and water is discharged from the needle on the wafer to form 25 µl of water droplets. A needle was inserted into the water drop, and the receding contact angle was measured at a frequency of once every second while sucking the water drop for 90 seconds at a rate of 10 μl / min. And after the measured value stabilized, the average value of the receding contact angle for 20 second was computed, and the average value was made into the receding contact angle.

In addition, the ¹³ C-NMR analysis which calculated | required content rate (mol%) of each structural unit in each polymer used the nuclear magnetic resonance apparatus (JNM-ECX400, Nippon Denshi make).

Each polymer was synthesize | combined using the monomer represented by the following general formula (M-1)-(M-10).

Synthesis Example 1 Synthesis of (A1-1)

(M-1) 0.37 g (5 mol%), (M-3) 19.39 g (93 mol%), (M-6) 0.24 g (2 mol%), and 2,2'- azobis as a polymerization initiator A monomer solution was prepared by dissolving 1.33 g of-(methyl 2-methylpropionate) in 20.00 g of isopropanol.

Meanwhile, 50 g of isopropanol was added to a 200 mL three-necked flask equipped with a thermometer and a dropping funnel and purged with nitrogen for 30 minutes. After nitrogen purging, the flask was heated to 80 ° C. while stirring with a magnetic stirrer.

And the monomer solution prepared previously was dripped over 3 hours using the dropping funnel. After completion of the dropwise addition, the reaction was further performed for 3 hours. Then, it cooled to 30 degrees C or less, and obtained the polymerization liquid.

The obtained polymerization liquid was concentrated to 60 g, and then transferred to a separating funnel. 150 g of n-heptane was thrown into this separating funnel, and separation purification was performed. The lower layer liquid was recovered after separation. 45 g of 4-methyl-2-pentanol and 95 g of water were added to the collected lower layer liquid to separate and purify, and the supernatant liquid was collected after separation. The recovered supernatant was substituted with 4-methyl-2-pentanol to obtain a solution containing polymer (A1-1). Mw of the obtained polymer (A1-1) was 10,000 and Mw / Mn was 1.6, and the yield was 50%. ^As a result of ¹³ C-NMR analysis, the content rate of the structural unit derived from (M-1), (M-3), and (M-6) was 5 mol%, 93 mol%, and 2 mol%, respectively.

Synthesis Examples 2 to 11 Synthesis of (A1-2) to (A2-5)

Each polymer was synthesize | combined similarly to the synthesis example 1 except having performed the kind and usage-amount of the monomer to mix | blend as shown in following Table 1. The receding contact angles, Mw and Mw / Mn of each polymer are shown in Table 1. In addition, in Table 1, "-" shows that the corresponding monomer is not mix | blended.

It showed below about components other than the polymer used for manufacture of the immersion upper layer film forming composition.

[B] solvent

B-1: 4-methyl-2-pentanol

B-2: diisoamyl ether

Example 1

80 parts by mass of (A1-1) as the polymer [A1], 20 parts by mass of (A2-1) as the polymer of [A2], and 3,730 parts by mass of (B-1) and 932 parts of mass (B-2) as the solvent [B]. The parts were combined to prepare a liquid immersion upper layer film-forming composition.

[Examples 2 to 24 and Comparative Examples 1 and 2]

Except having made the kind and compounding quantity (mass part) of each component mix | blended as shown in following Table 2, it operated similarly to Example 1, and prepared each liquid immersion upper layer film formation composition. In addition, "-" in Table 2 shows that the said component is not mix | blended.

The polymer contained in the resist composition was synthesized using the monomers represented by the following formulas (M-11) to (M-13).

[Synthesis Example 12]

In a 500 mL flask, 47.54 g (46 mol%) of (M-11), 12.53 g (15 mol%) of (M-12), 39.93 g (39 mol%) of (M-13), dimethyl 2,2'- 4.08 g of azobis (2-methylpropionate) and 200 g of 2-butanone were added, and a polymerization reaction was carried out at 80 ° C. for 6 hours under nitrogen. After the completion of the polymerization, the polymerization solution was cooled to 30 ° C. or lower by cooling with water, and then charged into 2,000 g of methanol to precipitate a polymer. The polymer was filtered off, and then 800 g of methanol was added to wash the polymer. The polymer was further separated by filtration, and then dried at 50 ° C. for 17 hours to obtain polymer (P-1) (73 g, yield 73%). This polymer had Mw of 5,700 and Mw / Mn of 1.7. Moreover, as a result of ¹³ C-NMR analysis, the air content of each structural unit derived from (M-11), (M-12), and (M-13) was 51.4 mol%, 14.6 mol%, and 34.0 mol%, respectively. It was coalescence.

&Lt; Preparation of resist composition >

100 parts by mass of (P-1) as a polymer, 1.5 parts by mass of triphenylsulfonium nonafluoro-n-butanesulfonate as an acid generator, and 1- (4-n-butoxynaphthalen-1-yl) tetrahydroti 6 parts by mass of fennium nonafluoro-n-butanesulfonate and 0.65 parts by mass of R-(+)-(tert-butoxycarbonyl) -2-piperidinemethanol as an acid diffusion control agent were mixed and added to the mixture. As a solvent, 2,900 parts by mass of propylene glycol monomethyl ether acetate, 1,250 parts by mass of cyclohexanone and 100 parts by mass of γ-butyrolactone were added to adjust the solid content concentration to 5% by mass, and filtered with a filter having a pore diameter of 30 nm, thereby providing a resist composition. Prepared.

Water repellency, solvent resistance, solubility, peel resistance and exposure margin were evaluated, and the results are shown in Table 3 below.

[Water repellency]

Each liquid immersion upper layer film-forming composition was spin-coated on a silicon wafer, and PB was performed at 90 ° C. for 60 seconds to form an immersion upper layer film having a thickness of 30 nm. Thereafter, the wafer is set in a receding contact angle measuring device (DSA-10, manufactured by KRUS), and water is discharged from the needle on the wafer to form 25 µl of water droplets. A needle was inserted into the water drop, and the receding contact angle was measured at a frequency of once every second while sucking the water drop for 90 seconds at a rate of 10 μl / min. After the measured value is stabilized, the average value of the receding contact angle for 20 seconds is calculated. When the value is 75 ° or more, the water repellency is particularly good, “AA”, 70 ° or more and less than 75 °, and good. It was set as "B".

[Content generation]

The silicon rubber cut out in the center was placed on the silicon wafer, and the cutout was filled with 10 mL of ultrapure water. Then, another silicon wafer on which the resist film and the liquid immersion upper layer film were formed was superimposed so as to contact the immersion upper layer film with ultrapure water. In addition, the resist film was formed by spin coating the resist composition on a wafer and baking at 115 ° C. for 60 seconds (film thickness 205 nm). In addition, the immersion upper layer film was formed by spin coating each of the immersion upper layer film-forming compositions on the resist film and baking at 90 ° C. for 60 seconds (film thickness of 30 nm).

After contacting the immersion upper layer film with ultrapure water for 10 seconds, the other silicon wafer is removed, the ultrapure water is recovered, and the elution amount of the acid generator and the acid diffusion control agent dissolved therein is determined using a liquid chromatography mass spectrometer (LC section). : SERIES1100 manufactured by AGILENT, MS part: Mariner manufactured by Perseptive Biosystems, Inc. The measurement was performed using one column (CAPCELL PAK MG, manufactured by Shiseido), measuring temperature: 35 ° C., flow rate: 0.2 mL / min, effluent solvent: water / methanol (3/7), and 0.1 mass% of formic acid. It was done by adding. At this time, both the acid generator and the acid diffusion control agent had good elution property when the elution amount was 5.0 × 10 ^-12 mol / cm 2 or less, and poor when at least one exceeded 5.0 × 10 ^-12 mol / cm 2. B ”.

[Soluble]

Each liquid immersion upper layer film forming composition was spin-coated on a silicon wafer, and PB was performed at 90 degreeC for 60 second, and the coating film with a film thickness of 90 nm was formed. And puddle development was performed for 60 second by 2.38 mass% TMAH aqueous solution, the wafer surface was observed after drying, and the result was made into solubility. At this time, when there was no residue, solubility was good "A", and when a residue was observed, it was set as bad "B".

[Peel resistance]

The resist composition was spin-coated on a silicon wafer not subjected to HMDS (hexamethyldisilazane) treatment, and PB was performed at 100 ° C. for 60 seconds to form a resist film having a thickness of 100 nm. Then, each liquid immersion upper layer film-forming composition was spin coated on the resist film, and PB was performed at 90 ° C. for 60 seconds to form an immersion upper layer film having a thickness of 30 nm. And it rinsed with pure water for 60 second using the semiconductor manufacturing apparatus (CLEAN TRACK ACT8, Tokyo Electron make), and dried. Then, the presence or absence of peeling of the immersion upper layer film was visually observed, and the result was made into peeling tolerance. At this time, when peeling was not observed, peeling resistance was made into "A" good, and it was set as "B" bad when it was observed.

[Exposure margin]

The resist composition was spin-coated on a silicon wafer, and PB was performed at 100 degreeC for 60 second, and the resist film of thickness 100nm was formed. Then, each liquid immersion upper layer film-forming composition was spin coated on the resist film, and PB was performed at 90 ° C. for 60 seconds to form an immersion upper layer film having a thickness of 30 nm. Subsequently, after performing liquid immersion exposure by ultrapure water (immersion medium) using a liquid immersion exposure apparatus (S610C, manufactured by Nikon) using a mask for forming a line and space having a line width of 50 nm, using a 1: 1 line and space, a 2.38 mass% TMAH aqueous solution. Was developed at 25 ° C. for 60 seconds, washed with water and dried to form a resist pattern. At this time, the exposure amount whose line width becomes +/- 10% of a design dimension is measured, the ratio of the said exposure amount with respect to an optimal exposure amount (the exposure amount in which 1: 1 line and space of a line width of 50 nm is formed) is computed, and this ratio Exposure margin was taken. In addition, the line width was measured using the scanning electron microscope (S9260A, the Hitachi High-Technology company). Under the present circumstances, when the said ratio was 15% or more, exposure margin was good "A", and if it was less than 15%, it was set as bad "B".

As can be seen from the results in Table 3, both the examples and the comparative examples were good for water repellency, solvent resistance and solubility. In addition, about the peeling tolerance and exposure margin, all the examples were favorable, although the comparative example was either bad.

The present invention can provide a composition for forming an immersion upper layer film and a method of forming a resist pattern capable of achieving a balanced balance between peeling resistance and exposure margin while satisfying properties for water repellency, solvent resistance and solubility. Therefore, the said immersion upper layer film forming composition and the resist pattern formation method can be applied suitably to the manufacturing process of the semiconductor device which further refine | miniaturizes a resist pattern.

Claims

[A1] A polymer having a structural unit (I-1) containing a group represented by the following formula (i),
[A2] a polymer different from the above [A1] polymer, and
[B] solvent
A liquid immersion upper layer film-containing composition containing a.

(Wherein R ¹ is a (n + 1) valent hydrocarbon group having 1 to 20 carbon atoms, n is an integer of 1 to 3)

The liquid immersion upper layer film forming composition according to claim 1, wherein the receding contact angle with water in the film-forming state of the polymer [A2] is larger than that of the polymer [A1].

The composition for forming a liquid immersion upper layer according to claim 1 or 2, wherein the structural unit (I-1) is represented by the following general formula (1).
&Lt; Formula 1 >

(In formula 1, R <^1> and n are synonymous with the said Formula (i), and R <^2> is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group.)

The at least 1 of any one of Claims 1-3 whose polymer [A2] is selected from the group which consists of a structural unit containing the group represented by following formula (2), and a structural unit containing the group represented by following formula (3). The composition for liquid immersion upper layer film which has a structural unit (II-1) of a species.
(2)

(3)

In Formula 2, R ³ and R ⁴ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a fluorinated alkyl group having 1 to 4 carbon atoms, provided that at least one of R ³ and R ⁴ is a fluorinated alkyl group having 1 to 4 carbon atoms ,
In Formula 3, R ⁵ is a fluorinated alkyl group having 1 to 20 carbon atoms)

The composition for immersion upper layer film formation according to any one of claims 1 to 4, wherein the polymer [A2] further has a structural unit (II-2) represented by the following general formula (4).
&Lt; Formula 4 >

(In formula 4, R <^6> is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group, and R <^7> is a C1-C12 monovalent fluorinated hydrocarbon group.)

The polymer [A1] consists of a structural unit containing the group represented by the following general formula (2 '), and a structural unit containing the group represented by the following general formula (3'). The liquid immersion upper layer film forming composition which further has at least 1 sort (s) of structural units (I-2) chosen from the group.

(In formula (2 '), R <^3> and R <^4> is synonymous with the said Formula (2),
In formula (3 '), R ⁵ is synonymous with formula (3)

The liquid immersion upper layer film forming composition according to any one of claims 1 to 6, wherein the polymer [A1] further has a structural unit (I-3) containing a sulfo group.

The composition for forming a liquid immersion upper layer film according to any one of claims 1 to 7, wherein the solvent [B] contains an ether solvent.

(1) forming a resist film on a substrate using a resist composition,
(2) Process of forming immersion upper layer film on the said resist film using the composition for liquid immersion upper layer film as described in any one of Claims 1-8,
(3) exposing the resist film and the liquid immersion upper layer film through a liquid immersion medium, and
(4) developing the exposed resist film and the liquid immersion upper layer film
Resist pattern forming method having a.