JP2012098433A - Radiation sensitive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist pattern having an excellent shape, and a scum margin, using a substrate having steps.SOLUTION: A radiation sensitive composition includes a polymer component comprising: at least one of a hydroxystyrene structure and a repeating unit which becomes a hydroxystyrene structure by action of an acid from a photoacid generator; and at least one kind selected from repeating units represented by the following general formulas.

Description

  The present invention relates to a radiation-sensitive composition useful as a resist suitable for ultrafine processing using various types of radiation such as ultraviolet rays, far ultraviolet rays, X-rays or charged particle beams.

  In the field of microfabrication represented by the manufacture of integrated circuit elements, conventionally, a resist film is formed on a substrate with a resin composition containing a polymer having an acid-dissociable group that can be deprotected by an acid, and a mask pattern is formed. The resist film is exposed to short-wave radiation (KrF excimer laser, ArF excimer laser, etc.) for exposure, and the exposed portion is removed with an alkali developer to form a fine resist pattern. Yes. At this time, a “chemically amplified resist” is used in which a radiation-sensitive acid generator that generates an acid upon irradiation with radiation is contained in the resin composition, and the sensitivity is improved by the action of the acid.

  As such a chemically amplified resist, for example, Patent Document 1 discloses a combination of a resin protected with a t-butyl group or a t-butoxycarbonyl group and a radiation-sensitive acid generator. Patent Document 2 discloses a combination of a resin protected with a silyl group and a radiation-sensitive acid generator. In addition, many reports have been made on chemically amplified resists such as a resist (Patent Document 3) containing a resin having an acetal group and a radiation-sensitive acid generator.

JP 59-45439 A JP-A-60-52845 JP-A-2-25850

  Here, in recent years, the structure of an integrated circuit element has become complicated, and formation of a three-dimensional transistor typified by Fin-FET has been performed. In forming such a three-dimensional structure, a resist pattern is patterned on a stepped substrate such as polysilicon. In this case, since the amount of light reaching the lower part of the step is insufficient during exposure, the solubility of the resist in the exposed portion is lowered on the lower part side of the step, and there arises a problem that the resist remains undissolved (hereinafter referred to as scum). . In particular, in the case of forming a resist pattern for an ion implantation mask, the lower layer antireflection film for preventing light reflection on the substrate cannot be used. Scum tends to occur.

  The present invention has been made in order to address the above-described problems. In a lithography process for a substrate having a step, even in a region where the amount of light exposure is low, such as a lower portion of the step or an intersection portion between the resist pattern and the step, development dissolution An object of the present invention is to provide a radiation-sensitive composition which can increase the speed, and thus has a good scum margin and a resist pattern having a good shape.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that at least one of a repeating unit containing a hydroxystyrene structure and a repeating unit that becomes a hydroxystyrene structure by the action of an acid, and a repeating having a specific structure. The present inventors have found that the above-mentioned problems can be solved by using a polymer component containing a unit as a constituent component of the radiation-sensitive composition, thereby completing the present invention.

  According to the present invention, there is provided a radiation-sensitive composition comprising a polymer component containing at least one polymer, a radiation-sensitive acid generator, and a solvent. At least one of a repeating unit containing a styrene structure and a repeating unit that becomes a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator, a repeating unit represented by the following general formula (1), There is provided a radiation-sensitive composition comprising a repeating unit represented by 2) and at least one selected from repeating units represented by the following general formula (3).

In (Equation (1), ^{R 1} is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, ^{R 2} and ^{R 3} are independently (i) cross, a hydrogen atom, a fluorine atom, 1 to 4 carbon atoms An alkyl group, or a C 1-4 fluoroalkyl group, or (ii) a C 4-20 divalent alicyclic hydrocarbon group containing carbon atoms bonded to each other, or A group obtained by removing two hydrogen atoms from a derivative of an alicyclic hydrocarbon having 4 to 20 carbon atoms, A is a divalent organic group, and B is a single bond or a divalent carbon atom having 1 to 20 carbon atoms. However, any one of R ² and R ³ is a fluorine atom or a fluoroalkyl group, or the above alicyclic structure formed by combining R ² and R ^3. The group which has has a fluorine atom.)

(In Formula (2), R ⁴ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ⁵ is a perfluoroalkyl group having 1 to 10 carbon atoms or 3 to 3 carbon atoms substituted with a fluorine atom. And a monovalent alicyclic hydrocarbon group of 10. D is a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms.)

In (Equation (3), ^{R 6} is a hydrogen atom or an alkyl group of 1 to 5 carbon ^atoms, R ^{7a, R 7b} and ^{R 7c} independently of one another, a hydrogen atom, 1 to 4 fluorine atoms or carbon atoms Provided that any one of R ^{7a to} R ^7c is a fluorine atom or a fluoroalkyl group having 1 to 4 carbon atoms.)

  In the present radiation-sensitive composition, the polymer component not only contains at least one of a repeating unit having a hydroxystyrene structure and a repeating unit having a hydroxystyrene structure by the action of an acid, Represented by the repeating unit (hereinafter also referred to as the repeating unit (a1)), the repeating unit represented by the general formula (2) (hereinafter also referred to as the repeating unit (a2)), and the general formula (3). Containing at least one selected from repeating units (hereinafter also referred to as repeating units (a3)). As a result, hydrophobic groups having fluorine atoms can be unevenly distributed on the resist surface, and accordingly, components having a high dissolution rate in the developing solution after the deprotection reaction are positively distributed on the substrate surface side. It becomes possible. Therefore, even a substrate having a step has excellent scum margin.

  The polymer component preferably includes the repeating unit (a1). Thereby, the dissolution rate with respect to the developing solution after the deprotection reaction can be increased also on the resist surface side. In particular, the scum margin can be improved while making the pattern shape suitable by having 0.1 to 50 mol% of the repeating unit (a1) with respect to all repeating units of the polymer component. It becomes possible to exhibit suitably.

  The polymer component preferably includes the repeating unit (a3). By having such a component having high hydrophobicity, it becomes easy to positively unevenly distribute a component having a high dissolution rate in the developer after the deprotection reaction to the substrate surface side. Therefore, even a substrate having a step has excellent scum margin. In particular, the composition having 0.1 to 30 mol% of the repeating unit (a3) with respect to all the repeating units of the polymer component is suitable for improving the scum margin while maintaining an appropriate resolution. Can be demonstrated.

  The polymer component includes a polymer [A1] containing at least one of a repeating unit having a hydroxystyrene structure and a repeating unit having a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator, and the repeating unit. (A1), a polymer [A2] containing at least one selected from the repeating unit (a2) and the repeating unit (a3) (excluding those having the same composition as the polymer [A1]), It is preferable to contain. This makes it possible to obtain a composition that exhibits the above excellent effects while facilitating production. Moreover, it is convenient to make the polymer components unevenly distributed on the resist surface side and the substrate side different in the resist film.

  Thus, when it has polymer [A1] and polymer [A2], it is preferable that polymer [A1] does not have a repeating unit containing a fluorine atom. This makes it possible to clearly vary the fluorine atom content between the polymer [A1] and the polymer [A2], and the polymer [A1] is unevenly distributed on the resist surface side. ] Is preferably unevenly distributed on the substrate side.

  The polymer [A2] preferably contains at least one of a repeating unit containing a hydroxystyrene structure and a repeating unit that becomes a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator. Thereby, the dissolution rate with respect to the developing solution after the deprotection reaction can be increased also on the resist surface side.

  Meanwhile, the polymer component includes at least one of a repeating unit containing a hydroxystyrene structure, and a repeating unit that becomes a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator, the repeating unit (a1), You may have a polymer containing a repeating unit (a2) and at least 1 sort (s) chosen from the said repeating unit (a3).

  As the repeating unit (a1), those represented by the following general formula (1-1) are preferable.

(In Formula (1-1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ¹¹ and R ¹² are each independently a fluorine atom or a fluoroalkyl group having 1 to 4 carbon atoms. B is a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms.)

  In this case, it is possible to provide a repeating unit (a1) having a reasonably high fluorine atom content and capable of increasing the dissolution rate in the developer after the deprotection reaction.

  In the present specification, the “acid-dissociable group” refers to a group that substitutes a hydrogen atom in a polar functional group such as a hydroxyl group or a carboxyl group and dissociates in the presence of an acid.

It is a schematic diagram which shows the silicon wafer in which the level | step difference by polysilicon was formed. FIG. 2 is a schematic diagram showing a state in which a resist pattern is formed on the silicon wafer of FIG. 1. It is a schematic diagram which expands and shows the part where the level | step difference by a polysilicon and a resist pattern orthogonally cross.

  The radiation sensitive composition of the present invention contains a polymer [A1]. Moreover, you may contain polymer [A2] in which a composition differs from polymer [A1] as another polymer component. Moreover, this composition contains a radiation sensitive acid generator [B] and a solvent [E]. Moreover, this composition may contain acid diffusion control agent [C], surfactant [D], etc. as a suitable arbitrary component. Hereinafter, each component will be described.

<Polymer component>
<Polymer [A1]>
The polymer [A1] in the present invention contains at least one of a repeating unit (HS) having a hydroxystyrene structure and a repeating unit (Ac1) having a hydroxystyrene structure by the action of an acid.

  Here, the “hydroxystyrene structure” is hydroxystyrene or a derivative thereof, and is a structure formed by cleavage of a polymerizable unsaturated bond of a compound having a phenolic hydroxyl group.

<Repeating unit (HS)>
The repeating unit (HS) is represented by the following general formula (HS-1). By having such a repeating unit (HS), the affinity for an alkaline developer can be improved.

(In the above formula, R ^H1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ^H2 is an optionally substituted alkyl group, alkoxy group or aryl group having 1 to 12 carbon atoms. Is an integer of 1 to 3, b is an integer of 0 to 3, and a + b is 1 to 5. When b is 2 or 3, R ^H2 has the above definition independently.

R ^H1 in the above formula is preferably a hydrogen atom or a methyl group.

  In the above formula, the bonding position of the hydroxyl group to the phenyl group is not particularly limited, but when a is 1, it may be o-position, m-position or p-position, preferably p-position. When a is 2 or 3, the bonding position is arbitrary.

The alkyl group having 1 to 12 carbon atoms of R ^H2 may be linear or branched, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group. , 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like.

The alkoxy group having 1 to 12 carbon atoms of R ^H2 may be linear or branched, for example, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group. , 2-methylpropoxy group, 1-methylpropoxy group, t-butoxy group and the like.

The aryl group having 1 to 12 carbon atoms R ^H2, for example, a phenyl group, a benzyl group, a tolyl group.

Each monovalent organic group of R ^H2 may be substituted. Examples of the substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom), hydroxyl group, carboxyl group, nitro group, cyano group. Groups and the like. Moreover, you may have 1 or more of the said substituents individually by 1 type, and you may have 1 or more each of multiple types.

R ^H2 is preferably a methyl group, an ethyl group, an n-butyl group, or a t-butyl group.

  a is preferably 1 or 2, more preferably 1. b is preferably 0 or 1, and more preferably 0 in view of ease of production. Particularly preferred as the repeating unit (HS) is a structural unit formed by cleavage of a polymerizable unsaturated bond of 4-hydroxystyrene.

  In the polymer [A1], the content of the repeating unit (HS) is preferably 20 to 90 mol% in total amount of the repeating unit (HS) with respect to all the repeating units constituting the polymer [A1], 30 to 85 mol% is more preferable, and 40 to 80 mol% is particularly preferable. By setting it as such a content rate, the polymer [A1] of an exposure part can fully be dissolved with respect to a developing solution, and it becomes possible to make the shape of a resist pattern favorable. Moreover, polymer [A1] may have a repeating unit (HS) individually by 1 type or in combination of 2 or more types.

<Repeating unit (Ac1)>
In the repeating unit (Ac1), the hydrogen atom of the phenolic hydroxyl group in the repeating unit having one or more phenolic hydroxyl groups was substituted with one or more acid dissociable groups capable of dissociating in the presence of an acid. As such, it is a repeating unit capable of forming a polymer that is insoluble or hardly soluble in alkali.

  The repeating unit (Ac1) is represented by the following general formula (Ac-1).

(In the above formula, R ^a1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ^a2 is a monovalent acid-dissociable group, k is an integer of 1 to 3. k is 2 or 3) In this case, each R ^a2 independently has the above definition.)

R ^a1 in the above formula is preferably a hydrogen atom or a methyl group.

Examples of the monovalent acid dissociable group for R ^a2 in the above formula include a 1-branched alkyl group, a triorganosilyl group, a triorganogermyl group, an alkoxycarbonyl group, an acyl group, and a monovalent cyclic acid dissociable group. Or a substituent represented by the following general formula (Ac-1-1).

(In the above formula, R ^a21 and R ^a22 are each independently a hydrogen atom or a methyl group, and R ^a23 is a hydrocarbon group having 1 to 8 carbon atoms.)

  Examples of the monovalent acid dissociable group include t-butyl group, benzyl group, 1-methoxyethyl group, 1-ethoxyethyl group, 1-phenoxyethyl group, trimethylsilyl group, t-butoxycarbonyl group, t-butoxycarbonyl group. A methyl group, a tetrahydrofuranyl group, a tetrahydropyranyl group, a tetrahydrothiofuranyl group, a tetrahydrothiopyranyl group and the like are preferable.

  The repeating unit (Ac1) is preferably k = 1. In this case, specifically, 4-t-butoxystyrene, 4- (2-ethyl-2-propoxy) styrene, 4- (1-ethoxy) styrene , T-butoxycarbonylstyrene, or t-butoxycarbonylmethylenestyrene, a repeating unit formed by cleavage of a polymerizable unsaturated bond.

  In the polymer [A1], the content of the repeating unit (Ac1) is such that the total amount of the repeating unit (Ac1) is 1 to 40 mol% with respect to all the repeating units constituting the polymer [A1]. Is preferable, it is more preferable that it is 5-35 mol%, and 15-30 mol% is especially preferable. By setting it as such a content rate, it becomes possible to make favorable the contrast of an exposed part and an unexposed part, and it becomes possible to make the shape of a resist pattern favorable. Moreover, polymer [A1] may have a repeating unit (Ac1) individually by 1 type or in combination of 2 or more types.

  The polymer [A1] may have both the repeating unit (HS) and the repeating unit (Ac1). The polymer [A1] may have one of the repeating unit (HS) and the repeating unit (Ac1). However, when the polymer [A1] has the repeating unit (HS) and does not have the repeating unit (Ac1), the polymer [A1] is different from the repeating unit (Ac1). A repeating unit having a group, or a polymer other than the polymer [A1] having a repeating unit having an acid dissociable group that is different from the repeating unit (Ac1) or the repeating unit (Ac1). Need to be. Other repeating units having an acid dissociable group will be described later.

<Repeating units (a1) to (a3)>
When this radiation sensitive composition has only the said polymer [A1] as a polymer component, the said polymer [A1] contains at least 1 sort (s) chosen from the following repeating unit (a1)-(a3). Need to be. Moreover, even if this composition has a polymer [A2] in addition to the polymer [A1], the polymer [A1] is at least one selected from the following repeating units (a1) to (a3). It may contain seeds. Hereinafter, the repeating units (a1) to (a3) will be described.

<Repeating unit (a1)>
The repeating unit (a1) has a fluorine atom. By having such a repeating unit (a1), the polymer component has a higher alkali solubility at the time of alkali development than the polymer [A1], and has a lower fluorine atom content than the polymer [A1]. When the coalescence exists, the other polymer is unevenly distributed on the substrate side as the polymer [A1] is unevenly distributed on the resist surface side. Thereby, in the lithography process of the stepped substrate, the developing dissolution rate can be increased even in a region where the exposure amount is low. It also has an alkali-soluble group. Therefore, the development dissolution rate can be increased even on the resist surface side.

  The repeating unit (a1) is represented by the following general formula (1).

(In the above formula, R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ² and R ³ are independently (i) a hydrogen atom, a fluorine atom, an alkyl having 1 to 4 carbon atoms. Group, or a fluoroalkyl group having 1 to 4 carbon atoms, or (ii) a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a carbon number containing carbon atoms bonded to each other. A group obtained by removing two hydrogen atoms from a derivative of an alicyclic hydrocarbon having 4 to 20. A is a divalent organic group, and B is a single bond or a divalent saturated group having 1 to 20 carbon atoms. An aliphatic hydrocarbon group, wherein either R ² or R ³ is a fluorine atom or a fluoroalkyl group, or a group having the above alicyclic structure formed by combining R ² and R ³ Has a fluorine atom.)

R ¹ in the above formula is preferably a hydrogen atom or a methyl group.

Among the groups represented by R ² and R ^{3 in the} above formula, the alkyl group having 1 to 4 carbon atoms or the fluoroalkyl group having 1 to 4 carbon atoms represented by the above (i) is linear and Any of branching may be sufficient. Specific examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, and t-butyl. Groups. Moreover, what substituted a part or all of these hydrogen atoms with the fluorine atom is mentioned as a specific example of a C1-C4 fluoroalkyl group.

  Preferably, as the divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms in the above (ii), two hydrogen atoms are removed from norbornane, tricyclodecane, tetracyclododecane, adamantane, cyclopentane, cyclohexane or the like. Groups.

  In addition, as the derivative of the alicyclic hydrocarbon having 4 to 20 carbon atoms in the above (ii), preferred are those obtained by substituting those listed as the alicyclic hydrocarbon having 4 to 20 carbon atoms. Examples of the substituent include an alkyl group having 1 to 4 carbon atoms, a fluorine atom, a hydroxyl group, a hydroxyalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, and a cyanoalkyl having 2 to 5 carbon atoms. Groups and the like. Among these, a hydroxyl group, a carboxyl group, a hydroxymethyl group, a cyano group, and a group substituted with a cyanomethyl group are preferable. Moreover, you may have 1 or more of the said substituents individually by 1 type, and you may have 1 or more each of multiple types.

  In the above formula, preferred examples of the divalent organic group represented by A include an oxygen atom, a carbonyl group, a carbonyloxy group, and an oxycarbonyl group. More preferably, it is a carbonyloxy group.

  The repeating unit (a1) is preferably represented by the following general formula (1-1).

(In the above formula, R ¹¹ and R ¹² are each independently a fluorine atom or a fluoroalkyl group having 1 to 4 carbon atoms. The definitions of R ¹ and B are the same as in the above formula (1). )

In the above formulas, as the fluoroalkyl group having 1 to 4 carbon atoms represented as R ¹¹ and R ^12, perfluoroalkyl group having 1 to 4 carbon atoms, mono perfluoroalkyl methyl group or C 2 to 4 carbon atoms A diperfluoroalkylmethyl group of 3 to 4 is preferable, and among them, a trifluoromethyl group is particularly preferable. Moreover, it is particularly preferable that both R ¹¹ and R ¹² are trifluoromethyl groups.

  When the repeating unit (a1) is a group represented by the general formula (1-1), the fluorine atom content of the repeating unit (a1) can be increased. Therefore, the other polymer is easily unevenly distributed on the substrate side. Furthermore, when A of the repeating unit (a1) is —COO—, the dissolution rate in the developer after the deprotection reaction can be suitably increased.

  In said Formula (1) and said Formula (1-1), as a C1-C20 bivalent saturated aliphatic hydrocarbon group represented by B, a C1-C20 alkanediyl group and carbon number Any of 3-20 divalent saturated alicyclic hydrocarbon groups may be sufficient.

  The alkanediyl group having 1 to 20 carbon atoms may be either linear or branched. Specifically, methylene group, ethylene group, propylene group such as 1,3-propylene group or 1,2-propylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene Group, decamethylene group, undecamethylene group, dodecamethylene group, tridecamethylene group, tetradecamethylene group, pentadecamethylene group, hexadecamethylene group, heptacamethylene group, octadecamethylene group, nonacamethylene group, insalen 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- Examples include 1,4-butylene group.

  The saturated alicyclic hydrocarbon group having 3 to 20 carbon atoms includes not only a group obtained by removing two hydrogen atoms from a structure composed only of a saturated alicyclic hydrocarbon structure, but also a saturated alicyclic carbonization group. A group in which two hydrogen atoms are removed from a combination of hydrogen and a chain structure is included.

Specifically, as a group obtained by removing two hydrogen atoms from a structure composed only of a saturated alicyclic hydrocarbon structure,
Cyclobutylene group such as 1,3-cyclobutylene group, cyclopentylene group such as 1,3-cyclopentylene group, cyclohexylene group such as 1,3-cyclohexylene group, 1,5-cyclooctylene A monocyclic hydrocarbon group such as a cycloalkylene group having 3 to 10 carbon atoms such as a cyclooctylene group such as a group;
Bridged cyclic carbonization such as 1,4-norbornylene group, 2,5-norbornylene group, 2,6-norbornylene group, etc. norbornylene, 1,5-adamantylene group, 2,6-adamantylene group, etc. A hydrogen group;
Etc.

  Specific examples of the group in which two hydrogen atoms are removed from those partially containing a chain structure include monocyclic hydrocarbons such as cyclobutane, cyclopentane, cyclohexane, and cyclooctane, or norbornane, adamantane, and the like. Examples include a group in which two hydrogen atoms have been removed from one or all of the hydrogen atoms in the bridged cyclic hydrocarbon substituted with an alkyl group having 1 to 4 carbon atoms.

  In the above formula (1), when A is a carbonyloxy group, or when it is the above formula (1-1), B is preferably a 2,5-norbornanediyl group, a 2,6-norbornanediyl group, or 1 , 2-propanediyl group.

Preferable specific examples of the monomer that gives the repeating unit (a1) include, for example, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester, (Meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoro) Methyl-2-hydroxy-5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2- {[5- (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester, (meta Acrylic acid 3 - {[8- (1 ', 1', 1'-trifluoro-2'-trifluoromethyl-2'-hydroxy) propyl] tetracyclo [6.2.1.1 ^{3, 6.} 0 ^2,7 ] dodecyl} ester and the like.

  In the polymer [A1], the content of the repeating unit (a1) is such that the total amount of the repeating unit (a1) is 0.1 to 50 mol% with respect to all the repeating units constituting the polymer [A1]. Preferably, it is 0.5 to 40 mol%, more preferably 1 to 20 mol%. The polymer [A1] may have a single repeating unit (a1) or a combination of two or more.

<Repeating unit (a2)>
The repeating unit (a2) has a hydrophobic group having a fluorine atom and is alkali-insoluble or alkali-insoluble. By having such a repeating unit (a2), the polymer component has a higher alkali solubility at the time of alkali development than the polymer [A1], and has a lower fluorine atom content than the polymer [A1]. When the coalescence exists, the other polymer is unevenly distributed on the substrate side as the polymer [A1] is unevenly distributed on the resist surface side. Thereby, in the lithography process of the stepped substrate, the developing dissolution rate can be increased even in a region where the exposure amount is low.

  The repeating unit (a2) is represented by the following general formula (2).

(In the above formula, R ⁴ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ⁵ is a perfluoroalkyl group having 1 to 10 carbon atoms or 3 to 10 carbon atoms substituted with a fluorine atom. (It is a monovalent alicyclic hydrocarbon group. D is a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms.)

R ⁴ in the above formula is preferably a hydrogen atom or a methyl group.

In the above formula, when R ⁵ is a perfluoroalkyl group having 1 to 10 carbon atoms, the alkyl group may be either linear or branched. Specific examples include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoro-n-propyl group, and a nonafluoro-n-butyl group.

In the case where R ⁵ is a C 3-10 monovalent alicyclic hydrocarbon group substituted with a fluorine atom, the C 3-10 monovalent alicyclic hydrocarbon group includes an adamantane skeleton, A group having a bridged skeleton such as a norbornane skeleton or a monocycloalkane skeleton such as cyclopentane or cyclohexane; these groups may include, for example, a carbon number such as a methyl group, an ethyl group, an n-propyl group, or an i-propyl group. Examples thereof include groups substituted with one or more of 1 to 5 linear or branched alkyl groups or alicyclic hydrocarbon groups. And as R < ⁵ >, what substituted some or all of the hydrogen atoms in these monovalent alicyclic hydrocarbon groups by the fluorine atom is mentioned.

R ⁵ is preferably a C 1-4 perfluoroalkyl group, particularly preferably a trifluoromethyl group.

  Specific examples of the divalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms represented by D in the above formula include the same as those described for B in the above formula (1). Can do. D is preferably a linear or alkanediyl group having 1 to 4 carbon atoms, and specifically includes a methylene group, an ethylene group, an n-propylene group, an i-propylene group, a tetramethylene group, and 2-methylpropylene. Group, 1-methylpropylene group. Of these, a methylene group or an ethylene group is particularly preferable.

  Preferable specific examples of the monomer that gives the repeating unit (a2) include, for example, [[(trifluoromethyl) sulfonyl] amino] ethyl-1- (meth) acrylate, 2-[[(trifluoromethyl) sulfonyl]. And amino] ethyl-1- (meth) acrylate, and compounds represented by the following formulas.

(In each formula, R ⁴ is the same as formula (2) above.)

  In the polymer [A1], the content of the repeating unit (a2) is such that the total amount of the repeating unit (a2) is 0.1 to 80 mol% with respect to all the repeating units constituting the polymer [A1]. It is preferably 20 to 80 mol%, more preferably 30 to 70 mol%. The polymer [A1] may have a single repeating unit (a2) or a combination of two or more.

<Repeating unit (a3)>
The repeating unit (a3) has a hydrophobic group having a fluorine atom and is alkali-insoluble or alkali-insoluble. By having such a repeating unit (a3), the polymer component has a higher alkali solubility at the time of alkali development than the polymer [A1], and has a lower fluorine atom content than the polymer [A1]. When the coalescence exists, the other polymer is unevenly distributed on the substrate side as the polymer [A1] is unevenly distributed on the resist surface side. Thereby, in the lithography process of the stepped substrate, the developing dissolution rate can be increased even in a region where the exposure amount is low.

  The repeating unit (a3) is represented by the following general formula (3).

(In the above formula, R ⁶ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ^7a , R ^7b and R ^7c are each independently a hydrogen atom, a fluorine atom or a fluoro having 1 to 4 carbon atoms. An alkyl group, provided that any one of R ^{7a to} R ^7c is a fluorine atom or a fluoroalkyl group having 1 to 4 carbon atoms.)

R ⁶ in the above formula is preferably a hydrogen atom or a methyl group.

In the above formula, as the C1-C4 fluoroalkyl group represented by R ^7a , R ^7b and R ^7c , those specifically described for R ¹¹ and R ¹² in the above formula (1-1) The same thing can be mentioned.

In order to suitably exhibit the function of unevenly distributing the polymer containing the repeating unit (a3) on the resist surface side, it is preferable that at least two of R ^7a , R ^7b and R ^7c are fluoroalkyl groups. Moreover, in order to make hydrophobicity moderate, it is preferable that two of R ^7a , R ^7b and R ^7c are fluoroalkyl groups and one is a hydrogen atom. Further, the fluoroalkyl group is preferably a trifluoromethyl group. In this case as well, the hydrophobicity can be made moderate.

  Preferable specific examples of the monomer that gives the repeating unit (a3) include, for example, (meth) acrylic acid [2- (1,1,1,3,3,3-hexafluoro) propyl] ester, (meth) Acrylic acid [2- (1,1,1,4,4,4-hexafluoro) butyl] ester, (meth) acrylic acid [3- (1,1,2,2,4,4,5,5- Octafluoro) pentyl] ester, (meth) acrylic acid [3- (1,1,2,2,5,5,6,6-octafluoro) hexyl] ester, and the like.

  In the polymer [A1], the content of the repeating unit (a3) is such that the total amount of the repeating unit (a3) is 0.1 to 30 mol% with respect to all the repeating units constituting the polymer [A1]. It is preferably 0.1 to 25 mol%, more preferably 0.1 to 20 mol%. The polymer [A1] may have the repeating unit (a3) alone or in combination of two or more.

<Other repeating units having an acid dissociable group>
A repeating unit having an acid-dissociable group, which is different from the repeating unit (Ac1), includes a hydrogen atom of the carboxyl group in the repeating unit having one or more carboxyl groups in the presence of an acid. Examples of the repeating unit substituted with one or more acid-dissociable groups capable of dissociation may include a repeating unit capable of forming an alkali-insoluble or alkali-insoluble polymer.

  Specifically, a repeating unit (Ac2) and a repeating unit (Ac3) can be mentioned.

<Repeating unit (Ac2)>
The repeating unit (Ac2) is represented by the following general formula (Ac-2).

(In the above formula, R ^a3 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ^a4 is a monovalent acid-dissociable group.)

R ^a3 in the above formula is preferably a hydrogen atom or a methyl group.

Examples of the monovalent acid dissociable group for R ^a4 in the above formula include the same groups as those described for R ^a4 in the above formula (Ac-1).

  The repeating unit (Ac2) is preferably t-butyl (meth) acrylate, 1-methyladamantyl (meth) acrylate, 1-ethyladamantyl acrylate, 1-methylcyclopentyl (meth) acrylate, or (meth) acrylic. Mention may be made of repeating units formed by cleavage of the polymerizable unsaturated bond in the acid 1-ethylcyclopentyl.

  In the polymer [A1], the content of the repeating unit (Ac2) is such that the total amount of the repeating unit (Ac2) is 0 to 60 mol% with respect to all the repeating units constituting the polymer [A1]. Is more preferable, and it is more preferable that it is 10-50 mol%, and 10-30 mol% is especially preferable. Moreover, polymer [A1] may have a repeating unit (Ac2) individually by 1 type or in combination of 2 or more types.

<Repeating unit (Ac3)>
The repeating unit (Ac3) is represented by the following general formula (Ac-3).

(In the above formula, R ^a5 and R ^a11 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ^a6 , R ^a7 , R ^a9 and R ^a10 are each independently an alkyl group. And R ^a8 is a divalent alkanediyl group.)

R ^a5 and R ^a11 in the above formula are preferably a hydrogen atom or a methyl group.

R ^a6 , R ^a7 , R ^a9 and R ^a10 in the above formula may be either linear or branched. These alkyl groups preferably have 1 to 4 carbon atoms, specifically, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methyl group. Examples thereof include a propyl group and a t-butyl group. Further, these alkyl groups are more preferably alkyl groups having 1 to 2 carbon atoms.

The divalent alkanediyl group represented by R ^a8 in the above formula preferably has 1 to 8 carbon atoms, and specific examples include a methylene group, an ethylene group, a propylene group, and a butylene group. More preferably, R ^a8 has 2 to 6 carbon atoms.

  Preferred examples of the repeating unit (Ac3) include 2,5-dimethylhexane-2,5-diacrylate and 2,5-dimethylhexane-2,5-dimethacrylate.

  In the polymer [A1], the content of the repeating unit (Ac3) is such that the total amount of the repeating unit (Ac3) is 0 to 20 mol% with respect to all the repeating units constituting the polymer [A1]. Is preferable, it is more preferable that it is 0-15 mol%, and 0-10 mol% is especially preferable. Moreover, polymer [A1] may have a repeating unit (Ac3) individually by 1 type or in combination of 2 or more types.

<Repeating unit (St)>
The polymer [A1] may have a repeating unit (St) represented by the following general formula (St-1).

(In the above formula, R ^b1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ^b2 is a fluorine atom or an alkyl group having 1 to 5 carbon atoms which may have a fluorine atom. Is an integer from 0 to 5, and when m is an integer from 2 to 5, the R ^b2 has the above definition independently.

R ^b1 in the above formula is preferably a hydrogen atom or a methyl group.

Specific examples of the alkyl group having 1 to 5 carbon atoms of R ^b2 in the above formula include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1- Examples thereof include a methylpropyl group and a t-butyl group. In this case, part or all of the hydrogen atoms of the alkyl group may be substituted with fluorine atoms.

  m is preferably an integer of 0 to 3, more preferably 0 or 1, and most preferably 0.

  In the polymer [A1], the content of the repeating unit (St) is such that the total amount of the repeating unit (St) is 0 to 20 mol% with respect to all the repeating units constituting the polymer [A1]. Is preferable, it is more preferable that it is 0-15 mol%, and 0-10 mol% is especially preferable. The polymer [A1] may have a single repeating unit (St) or a combination of two or more.

<Repeating unit (Lc)>
The polymer [A1] may have a repeating unit (Lc) represented by the following general formula (Lc1).

(In the above formula, R ^c1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ^c2 is a single bond or a divalent linking group, and R ^c3 is a monovalent organic group having a lactone structure or cyclic. (It is a monovalent organic group having a carbonate structure.)

R ^c1 in the above formula is preferably a hydrogen atom or a methyl group.

Specific examples of the divalent linking group (R ^c2 ) in the above formula include, for example, a C 1-10 divalent hydrocarbon group. The hydrocarbon group may be any of a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group, a combination thereof, and either saturated or unsaturated. May be. In the divalent hydrocarbon group having 1 to 10 carbon atoms, the methanediyl group is an oxygen atom, a sulfur atom, -NR'- (where R 'is a hydrogen atom or a monovalent organic group), carbonyl. The group, -CO-O- or -CO-NH- may be substituted.

Examples of the monovalent organic group having a lactone structure represented by R ^c3 in the above formula include those represented by the following formulas (Lc-1) to (Lc-6).

(In the formulas (Lc-1) to (Lc-6), R ^Lc1 is independently an oxygen atom or a methanediyl group. R ^Lc2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. NLc ₁ is each It is independently 0 or 1. nLc ₂ is an integer of 0 to 3. “*” represents a bond that binds to R ^c2 in the above formula (Lc1), and the formulas (Lc-1) to ( The group represented by Lc-6) may have a substituent.)

As a substituent which the group represented by the said formula (Lc-1)-(Lc-6) has, the example of the substituent which ^RH2 in the said formula (HS-1) has can be given.

Examples of the repeating unit having a cyclic carbonate structure as R ^c3 in the above formula include a structural unit represented by the following formula (Lc2).

(In the above formula, R ^c1 is the same as defined in the above formula (Lc1). R ^c4 is a trivalent chain hydrocarbon group having 1 to 30 carbon atoms, and a trivalent aliphatic group having 3 to 30 carbon atoms. A cyclic hydrocarbon group, or a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and R ^c4 may have an oxygen atom, a carbonyl group, or —NH— in its skeleton. R ^c4 may have a substituent.)

Examples of the substituent that R ^c4 may have include an example of the substituent that R ^H2 in the formula (HS-1) has.

  In the polymer [A1], the content of the repeating unit (Lc) is preferably such that the total amount of the repeating unit (Lc) with respect to all the repeating units constituting the polymer [A1] is 0 to 80 mol%. 0 to 70 mol% is preferable, and 0 to 60 mol% is more preferable. Polymer [A1] may have a repeating unit (Lc) individually by 1 type or in combination of 2 or more types.

<Other repeating units (Ot)>
The polymer [A1] may have another repeating unit (Ot). Examples of the other repeating unit (Ot) include a unit in which a polymerizable unsaturated bond of a vinyl aromatic compound or a (meth) acrylic acid ester derivative is cleaved, and other than the repeating unit already described. it can. Further, there may be mentioned units in which a polymerizable unsaturated bond is cleaved, such as carboxyalkyl esters of unsaturated carboxylic acids, unsaturated amide compounds, unsaturated imide compounds, nitrogen-containing vinyl compounds, and compounds having a norbornene skeleton.

  Specifically, the repeating unit (Ot1) represented by the following general formula (Ot-1), the repeating unit (Ot2) represented by the following general formula (Ot-2), and the following general formula (Ot-3) The repeating unit (Ot3) represented can be mentioned.

(In the formula (Ot-1), R ^d1 is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ^d2 and R ^d3 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. In said formula (Ot-2), ^Rd4 is a hydrogen atom or a C1-C5 alkyl group, ^Rd5 is a hydrogen atom, a methyl group, a C1-C5 perfluoroalkyl group, or C3-C3. And a monovalent cyclic hydrocarbon group of 20. In formula (Ot-3), R ^d6 is a monovalent organic group, and r is an integer of 0 to 2.)

R ^d1 in the above formula (Ot-1) and R ^d4 in the above formula (Ot-2) are preferably a hydrogen atom or a methyl group.

Specifically as a C1-C5 alkyl group represented by R ^{< d2>} and R ^<d3 > in said formula (Ot-1), a methyl group, an ethyl group, n-propyl group, i-propyl group, n-butyl Group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and the like, and a methyl group is preferable.

The monovalent cyclic hydrocarbon group having 3 to 20 carbon atoms represented by ^{R d5} in the above formula (Ot-2), preferably a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. Specifically, R ² and R ³ in the above formula (1) are bonded to each other, and from those mentioned as alicyclic hydrocarbons having 4 to 20 carbon atoms, each containing a bonded carbon atom. And groups in which one hydrogen atom is removed. A tricyclo [5.2.1.0 ^2,6 ] decyl group is preferable.

Examples of the monovalent organic group represented by R ^d6 in the above formula (Ot-3) include the same groups as those in R ^H2 in the above formula (HS-1). R is preferably 0.

  The polymer [A1] may have other repeating units (Ot) singly or in combination of two or more.

For example, the polymer [A1] is obtained by polymerizing a polymerizable unsaturated monomer corresponding to the repeating unit (HS) together with a polymerizable unsaturated monomer that gives another repeating unit in some cases, and then phenolic. It can be produced by introducing one or more monovalent acid-dissociable groups (R ^a2 ) into the hydroxyl group. In addition to this production method, it can be produced by copolymerizing a polymerizable unsaturated monomer corresponding to the repeating unit (Ac1) and a polymerizable unsaturated monomer that gives another repeating unit. .

  The polymer [A1] is preferably a copolymer having both a repeating unit (HS) and a repeating unit (Ac1). More preferably, the polymer [A1] has both the repeating unit (HS) and the repeating unit (Ac1), and the repeating units (a1) to (a3), (St), (Ac2), (Ac3), It is a copolymer containing at least one of (Ot). In this case, the polymer [A1] has both the repeating unit (HS) and the repeating unit (Ac1), and has at least one of the repeating unit (a1) and the repeating unit (a2). The dissolution rate with respect to the developer can be increased, and even a substrate having a step has excellent scum margin.

  The polystyrene-reduced weight average molecular weight (hereinafter also referred to as “Mw”) of the polymer [A1] by gel permeation chromatography (GPC) is not particularly limited, but is preferably 1,000 to 150,000, more preferably. Is 3,000-100,000.

  Further, the ratio (Mw / Mn) of Mw to the number average molecular weight (hereinafter also referred to as “Mn”) in terms of polystyrene by GPC of the polymer [A1] is usually 1 to 10, preferably 1 to 5. It is.

<Polymer [A2]>
The present radiation-sensitive composition has at least one selected from the repeating units (a1) to (a3) when the polymer [A1] does not contain any of the repeating units (a1) to (a3). It is necessary to provide the polymer [A2]. Further, even when the polymer [A1] contains at least one selected from the repeating units (a1) to (a3), if the composition is different from the polymer [A1], You may provide the polymer [A2] which has at least 1 sort (s) chosen from the said repeating unit (a1)-(a3).

  The polymer [A2] may have the above repeating units (a1) to (a3) singly or in combination of two or more. In this case, the polymer [A2] may have one type of repeating unit among the repeating units (a1) to (a3) singly or in combination of two or more types. In addition, the polymer [A2] has a combination of a plurality of types of repeating units among the repeating units (a1) to (a3), and each has a single type or a combination of two or more types of at least one repeating unit. May be.

  If the composition of the polymer [A2] is different from that of the polymer [A1], in addition to the repeating units (a1) to (a3), at least one of the repeating unit (HS) and the repeating unit (Ac1) is included. And may have, in addition to or instead of, having at least one repeating unit selected from the above repeating units (Ac2), (Ac3), (St), (Lc), (Ot). May be.

  By providing the polymer [A2] separately from the polymer [A1], when a resist is formed on the substrate with the present radiation-sensitive composition, the developer at the time of development on the resist surface side and the substrate side Thus, it is possible to suitably cause a difference in solubility. For example, by making the fluorine atom content of the polymer [A2] higher than that of the polymer [A1], the polymer [A2] is unevenly distributed on the resist surface side. It will be unevenly distributed. In this case, by making the solubility of the polymer [A1] at the time of development higher than that of the polymer [A2], the solubility on the resist surface side is made moderate, and the substrate side where the exposure amount is low. It becomes possible to increase the solubility of the.

  In producing such an action, the polymer [A2] preferably contains at least one of the repeating units (a1) to (a3), or the repeating units (a1) to (a3). The content of is preferably higher in the polymer [A2] than in the polymer [A1]. Among these, the polymer [A1] does not have the repeating units (a1) to (a3) in order to enhance the solubility on the substrate side while separating the unevenly distributed components on the resist surface side and the substrate side. The structure in which the polymer [A2] contains at least one of the repeating units (a1) to (a3) is preferable.

  Further, in the configuration in which the polymer [A2] has the repeating units (a1) to (a3) as described above, the solubility of the polymer [A1] during development is higher than that of the polymer [A2]. It is preferable that the polymer [A1] contains at least one of the repeating unit (HS) and the repeating unit (Ac1). More preferably, the polymer [A1] has the repeating unit (HS) and the repeating unit (Ac1).

When the polymer [A2] is unevenly distributed on the resist surface side as described above, the fluorine atom content [mass%] which is the ratio of fluorine atoms in the polymer [A2] is the ratio of the polymer [A2]. It is preferable that they are 1 mass% or more and 20 mass% or less with respect to mass. More preferably, it is 2 mass% or more and 15 mass% or less.

  Further, in relation to the polymer [A1], the fluorine atom content of the polymer [A2] is preferably as long as the polymer [A1] does not contain a fluorine atom. It is as the specific example already demonstrated as a rate. Moreover, if the polymer [A1] contains a fluorine atom, {the fluorine atom content of the polymer [A2] / the fluorine atom content of the polymer [A1]} is 1.2 or more and 20 or less. Is preferred.

  In order to improve the scum margin by including the polymer [A2], the polymer [A2] contains, in addition to the repeating units (a1) to (a3), the repeating unit (HS) and the repeating unit ( It is preferable to have at least one of Ac1). More preferably, it has both the repeating unit (HS) and the repeating unit (Ac1). In this case, the present radiation-sensitive composition is also suitable for use as a resist for a KrF excimer laser. Further, if the effect of causing the polymer [A2] to be unevenly distributed on the resist surface side as described above is caused, the polymer [A2] has the repeating unit (a3) and the repeating unit (HS). And having at least one of the repeating unit (Ac1), more preferably having the repeating unit (a3), the repeating unit (HS) and the repeating unit (Ac1). is there.

  In addition, in order to improve the scum margin by having the polymer [A2], the polymer [A2] does not have the repeating unit (Ac1) but the repeating unit (Ac2) and the repeating unit. It may have at least one of the units (Ac3). In this case, it is preferable that the polymer [A2] further has the repeating unit (Lc).

  Specifically, preferred examples of the polymer [A1] and the polymer [A2] include 4-hydroxystyrene / 4-t-butoxystyrene copolymer, 4-hydroxystyrene / 4-t-butoxystyrene / acrylic acid ( 1-methylcyclopentyl) ester copolymer, 4-hydroxystyrene / 4-t-butoxystyrene / acrylic acid (1-ethylcyclopentyl) ester copolymer, 4-hydroxystyrene / 4-t-butoxystyrene / styrene copolymer 4-hydroxystyrene / acrylic acid (t-butyl) ester / styrene copolymer, 4-hydroxystyrene / acrylic acid (1-methylcyclopentyl) ester / styrene copolymer, 4-hydroxystyrene / acrylic acid (1 -Ethylcyclopentyl) ester / styrene copolymer, 4-hydride Xylstyrene / 4-t-butoxystyrene / 2,5-dimethylhexane-2,5-diacrylate copolymer, 4-hydroxystyrene / 4-t-butoxystyrene / N, N-dimethylmethacrylamide copolymer, 4 -Hydroxystyrene / 4-t-butoxystyrene / methacrylic acid [2- (1,1,1,3,3,3-hexafluoro) propyl] ester copolymer, 4-hydroxystyrene / 4-t-butoxystyrene / Styrene / methacrylic acid [2- (1,1,1,3,3,3-hexafluoro) propyl] ester copolymer, 4-hydroxystyrene / 4-tert-butoxystyrene / styrene / methacrylic acid (1, 1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester copolymer, 4-hydroxystyrene / 4-t-butoxystyrene / methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester copolymer, 4-hydroxystyrene / 4-t-butoxystyrene / [[(Trifluoromethyl) sulfonyl] amino] ethyl-1-methacrylate copolymer and the like.

In addition to the above polymer [A2], methacrylic acid {4-oxa-5-oxotricyclo [4,2,1,03,7] nonan- ³ -yl} ester / methacrylic acid {Tricyclo [4.3.0.1 ^2,5 ] decan-3-yl} ester / acrylic acid (1-ethylcyclopentyl) ester / methacrylic acid [2- (1,1,1,3,3,3- Hexafluoro) propyl] ester copolymer, methacrylic acid {4-oxa-5-oxotricyclo [4,2,1,0,3,7] nonan- ³ -yl} ester / methacrylic acid (1,1,1 -Trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester / acrylic acid (1-ethylcyclopentyl) ester copolymer, methacrylic acid {tricyclo [4.3.0.1 ^2,5 ] And decane-3-yl} ester / [[(trifluoromethyl) sulfonyl] amino] ethyl-1-methacrylate / acrylic acid (1-ethylcyclopentyl) ester copolymer.

  The weight average molecular weight in terms of polystyrene (hereinafter also referred to as “Mw”) by gel permeation chromatography (GPC) of the polymer [A2] is not particularly limited, but is preferably 1,000 to 150,000, more preferably. Is 3,000-100,000.

  Further, the ratio (Mw / Mn) of Mw to the number average molecular weight in terms of polystyrene (hereinafter also referred to as “Mn”) by GPC of the polymer [A2] is usually 1 to 10, preferably 1 to 5. It is.

  The polymer component of the present radiation-sensitive composition may include one each of the polymer [A1] and the polymer [A2]. The polymer [A1] and the polymer [A2] Two or more of at least one may be included while including both.

  Here, the content of the repeating units (Ac1) to (Ac3) having an acid dissociable group in the polymer component is preferably 5 mol% or more and 40 mol% or less, more preferably 10 mol% or more and 35 mol%. % Or less, particularly preferably 15 mol% or more and 30 mol% or less.

  The rate of introduction of acid-dissociable groups (ratio of the number of acid-dissociable groups to the total number of unprotected acidic functional groups and acid-dissociable groups in the polymer component) is the acid-dissociable group and the group. However, it is preferably 10 to 100%, more preferably 15 to 60%.

  When the repeating unit (HS) is contained in the polymer component, the content is preferably 40 mol% or more and 85 mol% or less, more preferably 50 mol% or more and 80 mol% or less, and 60 mol% or more. 75 mol% or less is particularly preferable.

  When the polymer component contains the repeating unit (a1), the content is preferably 0.1 mol% or more and 50 mol% or less. By making it 0.1 mol% or more, the effect of improving the scum margin is suitably exhibited, and by making it 50 mol% or less, the pattern shape becomes suitable. The content of the repeating unit (a1) is more preferably from 0.5 mol% to 40 mol%, and particularly preferably from 1 mol% to 20 mol%.

  When the polymer component contains the repeating unit (a2), the content is preferably 0.1 mol% or more and 80 mol% or less. By making it 0.1 mol% or more, the effect of improving the scum margin is suitably exhibited, and by making it 80 mol% or less, the pattern shape becomes suitable. The content of the repeating unit (a2) is more preferably 20 mol% or more and 80 mol% or less, and particularly preferably 30 mol% or more and 70 mol% or less.

  When the polymer component contains the repeating unit (a3), the content is preferably 0.1 mol% or more and 30 mol% or less. By setting it to 0.1 mol% or more, the effect of improving the scum margin is suitably exhibited, and by setting it to 30 mol% or less, the resolution can be made moderate. The content of the repeating unit (a3) is more preferably from 0.1 mol% to 25 mol%, and particularly preferably from 0.1 mol% to 20 mol%.

<Radiation-sensitive acid generator [B]>
The radiation-sensitive acid generator [B] (hereinafter referred to as acid generator [B]) is a component that generates an acid upon exposure. As the acid generator [B], a nonionic radiation sensitive acid generator is preferable. As a nonionic radiation sensitive acid generator, the sulfonyloxyimide compound represented by the following general formula (B-1) can be mentioned, for example.

(In the above formula, R ²² represents an alkylene group, an arylene group, an alkoxylene group, a cycloalkylene group, a divalent group such as a cycloalkylene group containing a cyclic skeleton having an unsaturated bond, and R ²³ represents a halogen atom, This represents an alkyl group optionally substituted with an alkyl group, an alkyl group, a cycloalkyl group optionally substituted with a group having an ester bond, an aryl group optionally substituted with a halogen atom or an alkyl group.

  In this invention, a sulfonyloxyimide compound can be used individually or in mixture of 2 or more types.

  Specific examples of the sulfonyloxyimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (10-camphorsulfonyloxy) succinimide. N- (4-toluenesulfonyloxy) succinimide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (benzenesulfonyl) Oxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N-{(5-methyl-5-carboxymethylbicyclo [2.2.1] heptan-2-yl) Sulfonyloxy} succinimide and the like.

  As other nonionic acid generators, sulfonyldiazomethane compounds are preferred. As a sulfonyl diazomethane compound, the compound represented by the following general formula (B-2) can be mentioned, for example.

(In the above formula, each R ²⁴ independently represents a monovalent group such as an alkyl group, an aryl group, a halogen-substituted alkyl group, or a halogen-substituted aryl group.)

  Specific examples of the sulfonyldiazomethane compound include bis (trifluoromethanesulfonyl) diazomethane, bis (cyclohexanesulfonyl) diazomethane, bis (phenylsulfonyl) diazomethane, bis (4-toluenesulfonyl) diazomethane, and bis (2,4-dimethylbenzenesulfonyl). Diazomethane, bis (4-t-butylphenylsulfonyl) diazomethane, bis (4-chlorobenzenesulfonyl) diazomethane, methylsulfonyl, 4-toluenesulfonyldiazomethane, cyclohexanesulfonyl, 4-toluenesulfonyldiazomethane, cyclohexanesulfonyl, 1,1-dimethylethane Sulfonyldiazomethane, bis (1,1-dimethylethanesulfonyl) diazomethane, bis (1-methylethanesulfonyl) dia Examples include methane, bis (3,3-dimethyl-1,5-dioxaspiro [5.5] dodecane-8-sulfonyl) diazomethane, bis (1,4-dioxaspiro [4.5] decan-7-sulfonyl) diazomethane, and the like. be able to.

  As the acid generator [B], an onium salt that generates benzenesulfonic acid which may be substituted with a fluorine atom can be used.

  Specific examples of the onium salt compound include compounds represented by the following general formula (B-3) or (B-4).

(In the above formula (B-3), R ²⁵ and R ²⁶ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms which may be substituted, or may be substituted. It may be a good aryl group having 6 to 18 carbon atoms, or R ²⁵ and R ²⁶ may be bonded to each other to form a cyclic structure together with the iodine atom in the formula (B-4) , R ²⁷ , R ²⁸ , and R ²⁹ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms that may be substituted, or 6 to 6 carbon atoms that may be substituted. 18 aryl groups, or any two of R ²⁷ , R ²⁸ , and R ²⁹ are bonded to each other to form a cyclic structure with a sulfur atom in the formula, and the other one is substituted. C1-C10 linear or branched Alkyl group, or a optionally substituted aryl group having 6 to 18 carbon atoms.)

In the formula (B-3) and (B-4), X ^- is R-SO ₃ ^- or R-COOH ^- represents, R- is a fluorine atom, a hydroxyl group, an alkoxyl group, may be substituted with a carboxyl group Represents an alkyl group or an aromatic derivative.

Preferred R—SO ₃ ^— includes trifluoromethanesulfonate, nonafluoro-n-butanesulfonate, benzenesulfonate, 10-camphorsulfonate, 2-trifluoromethylbenzenesulfonate, 4-trifluoromethylbenzenesulfonate, and 2,4-difluorobenzene. Sulfonate, perfluorobenzene sulfonate, 2- (bicyclo [2.2.1] heptan-2-yl) -1,1-difluoroethane sulfonate, 2- (bicyclo [2.2.1] heptan-2-yl) ethane Mention may be made of sulfonates.

Preferred R-COOH in ^{- -} the formula (B-3) and X used in the (B-4) as the example, a group represented by the following formula (X-1) ~ formula (X-8) It is done.

  Examples of acid generators other than the above include disulfonylmethane compounds, oxime sulfonate compounds, hydrazine sulfonate compounds, and the like.

  As a disulfonylmethane compound, the compound represented by the following general formula (B-5) can be mentioned, for example.

(In the above formula, each R ³⁰ is independently a linear or branched monovalent aliphatic hydrocarbon group, cycloalkyl group, aryl group, aralkyl group, or other monovalent organic group having a hetero atom. V and W each independently represent an aryl group, a hydrogen atom, a linear or branched monovalent aliphatic hydrocarbon group, or another monovalent organic group having a hetero atom, and V And W is an aryl group, or V and W are connected to each other to form a carbon monocyclic structure or a carbon polycyclic structure having at least one unsaturated bond, or V and W May be connected to each other to form a group represented by the following general formula (B-6).

In the above formula, V ′ and W ′ are independent of each other, and a plurality of V ′ and W ′ may be the same or different, and each represents a hydrogen atom, a halogen atom, a linear or branched alkyl group, a cyclo Represents an alkyl group, an aryl group or an aralkyl group, or V ′ and W ′ bonded to the same or different carbon atoms are connected to each other to form a carbon monocyclic structure, and n is an integer of 2 to 10 It is. )

  As said oxime sulfonate compound, the compound represented by the following general formula (B-7) or (B-8) can be mentioned, for example.

(In the above formula (B-7) and the above formula (B-8), each R ³¹ and each R ³² independently represent a monovalent organic group.)

  These other acid generators can be used alone or in admixture of two or more.

  In the present invention, the amount of the acid generator [B] used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 25 parts by mass per 100 parts by mass of the polymer component. In this case, when the amount of the acid generator [B] used is 0.1 parts by mass or more, the sensitivity and developability become appropriate, while when it is 30 parts by mass or less, transparency to radiation, pattern Good shape, heat resistance and the like.

  The ratio of the acid generator other than the sulfonyloxyimide compound, the sulfonyldiazomethane compound, and the onium salt compound that generates a benzenesulfonic acid optionally substituted with a fluorine atom is based on the total amount of the acid generator [B]. Usually, it is 30% by mass or less, preferably 10% by mass or less.

  The radiation-sensitive composition of the present invention can contain an acid diffusion controller [C] and a surfactant [D].

<Acid diffusion controller [C]>
The acid diffusion controller [C] is a component having an action of controlling a diffusion phenomenon in the resist film of an acid generated from the acid generator [B] by exposure and suppressing an undesirable chemical reaction in a non-exposed region.

  By containing such an acid diffusion controller [C], the storage stability of the resulting radiation-sensitive composition is improved. In addition, the resolution of the formed resist film is further improved, and changes in the line width of the resist pattern due to fluctuations in the holding time (PED) after exposure until heat treatment can be suppressed, thereby improving process stability. An extremely excellent radiation sensitive composition is obtained.

  Examples of the acid diffusion controller [C] include nitrogen-containing organic compounds.

  Examples of the nitrogen-containing organic compound include a compound represented by the following general formula (C-1) (hereinafter referred to as “nitrogen-containing compound (i)”), and the same molecule represented by the following general formula (C-2). A compound having two nitrogen atoms (hereinafter referred to as “nitrogen-containing compound (ii)”), a polyamino compound or polymer having three or more nitrogen atoms (hereinafter referred to as “nitrogen-containing compound (iii)”) And amide group-containing compounds represented by the following general formula (C-3), urea compounds, nitrogen-containing heterocyclic compounds, and the like.

(In the above formula, R ^{33 s} are independently of each other a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, an optionally substituted aryl group, or an optionally substituted group. A good aralkyl group.)

  Examples of the nitrogen-containing compound (i) include substituted alkylamines such as di (cyclo) alkylamines, tri (cyclo) alkylamines and trialcoholamines, and aromatic amines such as anilines.

(In the above formula, R ^{34 s} are independently of each other a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, an optionally substituted aryl group, or an optionally substituted group. A good aralkyl group is shown, and L ′ represents a single bond or an alkylene group having 1 to 6 carbon atoms, an ether group, a carbonyl group or an alkoxycarbonyl group.

  Examples of the nitrogen-containing compound (iii) include triazines, polyethyleneimine, polyallylamine, 2-dimethylaminoethylacrylamide polymer, and the like.

  As an amide group containing compound, the compound represented by the following general formula (C-3) can be mentioned, for example.

(In the above formula, R ^{35 s} are independently of each other a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, an optionally substituted aryl group, or an optionally substituted group. Represents a good aralkyl group, and R ³⁵ may be bonded to each other to form a heterocyclic structure, and R ³⁶ is a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms which may have a substituent. Represents an optionally substituted aryl group or an optionally substituted aralkyl group.)

  Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea. Etc.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles, pyridines, piperazines, piperidines, triazines, and morpholines, as well as pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, and 1,4-diazabicyclo [2. 2.2] A preferred example is octane.

  The acid diffusion controller [C] can be used alone or in admixture of two or more.

  The compounding amount of the acid diffusion controller [C] is usually 15 parts by mass or less, preferably 0.001 to 10 parts by mass, more preferably 0.005 to 5 parts by mass per 100 parts by mass of the polymer component. . When the blending amount of the acid diffusion controller [C] is 15 parts by mass or less, the sensitivity as a resist and the developability of the exposed part are suitable. Moreover, when the compounding quantity of acid diffusion control agent [C] is 0.001 mass part or more, the pattern shape and dimensional fidelity as a resist will become favorable.

<Surfactant [D]>
As surfactant [D], what shows the effect | action which improves the applicability | paintability and striation of a composition, the developability as a resist, etc. can be used.

  Examples of such surfactant [D] include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenol ether, polyoxyethylene n-nonylphenol ether, polyethylene glycol. Examples include dilaurate and polyethylene glycol distearate. As commercial products, for example, F-top EF301, EF303, EF352 (manufactured by Tochem Products), Megafax F171, F173 (manufactured by Dainippon Ink & Chemicals, Inc.), Florard FC430, FC431 (Sumitomo 3M Co., Ltd.), Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, SC104, SC105, SC106 (Asahi Glass Co., Ltd.), KP341 (Shin-Etsu Chemical Co., Ltd.) Manufactured by Co., Ltd.), Polyflow No. 75, no. 95 (manufactured by Kyoeisha Chemical Co., Ltd.).

  The surfactant [D] can be used alone or in admixture of two or more.

  The blending amount of the surfactant [D] is usually 2 parts by mass or less per 100 parts by mass of the polymer component.

<Solvent [E]>
The positive radiation-sensitive composition of the present invention usually has a solvent [E] such that the concentration of the total solid content is usually 0.1 to 50% by mass, preferably 1 to 40% by mass when used. ] And then, for example, by filtering with a filter having a pore size of about 0.2 μm, it is prepared as a composition solution.

Examples of the solvent [E] used for preparing the composition solution include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol mono-n-butyl ether acetate, and the like. Ethylene glycol monoalkyl ether acetates; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether; propylene glycol dimethyl ether, propylene Glycol diethyl ether, propylene glycol di-n-propyl ether, propylene Propylene glycol dialkyl ethers such as glycol di-n-butyl ether; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-n-butyl ether acetate Alkyl ether acetates;
Lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, i-propyl lactate; n-amyl formate, i-amyl formate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate , Aliphatic carboxylic acid esters such as i-butyl acetate, n-amyl acetate, i-amyl acetate, i-propyl propionate, n-butyl propionate and i-butyl propionate; ethyl hydroxyacetate, 2-hydroxy- Ethyl 2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, 3-ethoxypropion Ethyl acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate , Other esters such as 3-methyl-3-methoxybutyl propionate, 3-methyl-3-methoxybutyl butyrate, methyl acetoacetate, ethyl acetoacetate, methyl pyruvate, ethyl pyruvate; toluene, xylene Aromatic hydrocarbons such as methyl ethyl ketone, 2-pentanone, 2-hexanone, 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone and the like; N-methylformamide, N, N-dimethylformamide, N- Amides such as methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone; Lactones such as γ-butyrolacun;
Etc.

  These solvents [E] can be used alone or in admixture of two or more.

<Method for forming photoresist pattern>
The resist pattern forming method of the present invention includes (1) a step of forming a photoresist film on a substrate using a radiation-sensitive composition (hereinafter also referred to as “step (1)”), and (2) formation. A step of irradiating the exposed photoresist film with radiation through a mask having a predetermined pattern for exposure (hereinafter also referred to as “step (2)”), and (3) developing the exposed resist film. And a step of forming a resist pattern (hereinafter also referred to as “step (3)”).

  In the step (1), the solution of the radiation-sensitive composition of the present invention is applied to a substrate such as a silicon wafer or a wafer coated with aluminum by an appropriate application means such as spin coating, cast coating or roll coating. A resist film is formed by applying on the top. Specifically, after applying the radiation-sensitive composition solution so that the resulting resist film has a predetermined film thickness, the resist film is formed by volatilizing the solvent in the film by pre-baking (PB). The

  As the substrate on which the resist film is to be formed, a substrate having a step formed by polysilicon on the substrate surface may be used. The thickness of the resist film is not particularly limited, but is preferably 10 to 5000 nm, and more preferably 10 to 2000 nm. Moreover, although the prebaking heating conditions change with composition of a radiation sensitive resin composition, it is preferable that it is about 30-200 degreeC, More preferably, it is 50-150 degreeC.

  In the step (2), the resist film formed in the step (1) is irradiated with radiation and exposed. In this case, radiation is irradiated through a mask having a predetermined pattern.

  The radiation is appropriately selected from visible rays, ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams and the like depending on the type of acid generator used. Among these, far ultraviolet rays represented by ArF excimer laser (wavelength 193 nm) and KrF excimer laser (wavelength 248 nm) are preferable, and KrF excimer laser is particularly preferable.

  Moreover, exposure conditions, such as exposure amount, can be suitably selected according to the compounding composition of a radiation sensitive composition, the kind of additive, etc. In the present invention, it is preferable to perform heat treatment (PEB) after exposure. By this PEB, the dissociation reaction of the acid dissociable group in the resin component can be smoothly advanced. Although the heating conditions of PEB are suitably adjusted with the compounding composition of a radiation sensitive composition, they are 30-200 degreeC normally, Preferably it is 50-170 degreeC.

  In the step (3), a predetermined resist pattern is formed by developing the exposed resist film.

  Examples of the developer used in this development step include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-. Propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5- An alkaline aqueous solution in which at least one alkaline compound such as diazabicyclo- [4.3.0] -5-nonene is dissolved is preferable.

  The concentration of the alkaline aqueous solution is preferably 10% by mass or less. When the concentration of the alkaline aqueous solution exceeds 10% by mass, the unexposed area may be dissolved in the developer.

  An appropriate amount of a surfactant or the like can be added to the developer composed of the alkaline aqueous solution.

  An organic solvent can also be added to the developer composed of the alkaline aqueous solution. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, methyl i-butyl ketone, cyclopentanone, cyclohexanone, 3-methylcyclopentanone, and 2,6-dimethylcyclohexanone; methyl alcohol, ethyl alcohol, and n-propyl alcohol. Alcohols such as i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclopentanol, cyclohexanol, 1,4-hexanediol and 1,4-hexanedimethylol; ethers such as tetrahydrofuran and dioxane; Examples thereof include esters such as ethyl acetate, n-butyl acetate and i-amyl acetate; aromatic hydrocarbons such as toluene and xylene; phenol, acetonylacetone and dimethylformamide. These organic solvents may be used individually by 1 type, and may be used in combination of 2 or more type. The amount of the organic solvent used is preferably 100 parts by volume or less with respect to 100 parts by volume of the alkaline aqueous solution. When the usage-amount of an organic solvent exceeds 100 volume part, developability may fall and there exists a possibility that the image development residue of an exposure part may increase.

  In addition, after developing with the developing solution which consists of alkaline aqueous solution, generally it wash | cleans with water and dries.

  Here, when using a substrate having a step formed by polysilicon on the surface of the substrate as described above, the amount of light reaching the lower portion of the step is insufficient during exposure. There is a concern that the solubility of the resist becomes low and the resist remains undissolved. In contrast, in the present radiation-sensitive composition, the polymer component only contains at least one of a repeating unit (HS) containing a hydroxystyrene structure and a repeating unit (Ac1) that becomes a hydroxystyrene structure by the action of an acid. Instead, it contains at least one selected from the above repeating units (a1) to (a3).

  By including any one of the repeating units (a1) to (a3) in the polymer component of the radiation-sensitive composition, the deprotection reaction occurs as the hydrophobic group having a fluorine atom is unevenly distributed on the resist surface. A component having a high dissolution rate in the later developing solution can be positively distributed on the substrate surface side. Thereby, even if there is a stepped substrate, the scum margin is excellent.

  In the present invention, in order to maximize the potential of the radiation-sensitive resin composition, for example, as disclosed in Japanese Patent Publication No. 6-12452 (JP 59-93448 A) and the like, An organic or inorganic antireflection film may be formed on the substrate to be used.

  However, when the resist pattern is used for an ion implantation mask, the antireflection film is not used. When an antireflection film is not used, the scum is more likely to occur during exposure due to the influence of standing waves due to reflection from the substrate. On the other hand, by using the present radiation-sensitive composition, the occurrence of scum can be suitably suppressed even when the antireflection film is not used.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples. The measuring method of various physical property values is shown below.

<Weight average molecular weight (Mw), number average molecular weight (Mn)>
Using a GPC column (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by Tosoh Corporation, with a flow rate of 1.0 ml / min, tetrahydrofuran as the elution solvent, and monodisperse polystyrene as the standard at a column temperature of 40 ° C. Measured by gel permeation chromatography (GPC).

< ^13C -NMR analysis>
The ¹³ C-NMR analysis of the polymer was measured using a nuclear magnetic resonance apparatus (“JNM-ECX400” manufactured by JEOL Ltd.).

<Synthesis of copolymer>
The monomers used for the synthesis of each copolymer are shown below as formulas (L-1) to (L-13).

<Synthesis Example 1>
117 g of the compound represented by the above formula (L-1), 41 g of the compound represented by the above formula (L-2), 5 g of the compound represented by the above formula (L-3), azobisisobutyronitrile (AIBN) ) 6 g and 1 g of t-dodecyl mercaptan were dissolved in 160 g of propylene glycol monomethyl ether, followed by polymerization for 16 hours while maintaining the reaction temperature at 70 ° C. in a nitrogen atmosphere. After the polymerization, the reaction solution was dropped into a large amount of n-hexane, and the resulting polymer was coagulated and purified.

  Next, 150 g of propylene glycol monomethyl ether was added again to the purified polymer, and then 300 g of methanol, 80 g of triethylamine and 15 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in acetone, then dripped into a large amount of water to solidify, and the resulting white powder was filtered and filtered under reduced pressure at 50 ° C. overnight. Dried (94 g, 71% yield).

The obtained polymer was Mw = 16,000 and Mw / Mn = 1.7. Further, ¹³ C-NMR analysis revealed that a repeating unit represented by the following formula (A-1), the content of each repeating unit (molar ratio), p1 / p2 / p3 = 72 /23 / It was 5.

<Synthesis Example 2>
182 g of the compound represented by the above formula (L-1), 66 g of the compound represented by the above formula (L-2), 11 g of the compound represented by the above formula (L-4), 14 g of AIBN and 11 g of t-dodecyl mercaptan. After being dissolved in 240 g of propylene glycol monomethyl ether, polymerization was carried out for 16 hours while maintaining the reaction temperature at 70 ° C. in a nitrogen atmosphere. After the polymerization, the reaction solution was dropped into a large amount of n-hexane to solidify and purify the produced polymer, and dried at 50 ° C. under reduced pressure for 3 hours.

  Next, 150 g of propylene glycol monomethyl ether was added again to 190 g of this purified polymer, and then 300 g of methanol, 100 g of triethylamine and 15 g of water were further added, and a hydrolysis reaction was carried out for 8 hours while refluxing at the boiling point. After the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the obtained polymer was dissolved in acetone, then dropped into a large amount of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. under reduced pressure overnight. Dried (157 g, 74% yield).

The obtained polymer was Mw = 27,000 and Mw / Mn = 2.6. Moreover, it has a repeating unit represented by a following formula (A-2) as a result of < ¹³ > C-NMR analysis, The content rate (molar ratio) of each repeating unit is p1 / p2 / p3 = 75/22 / 3.

<Synthesis Example 3>
Instead of the compound 117g represented by the above formula (L-1), the compound 41g represented by the above formula (L-2), and the compound 5g represented by the above formula (L-3), the above formula (L <Synthesis Example 1> except that the compound 114g represented by -1), the compound 35g represented by the above formula (L-2) and the compound 11g represented by the above formula (L-5) were used. In the same manner as above, a polymer was obtained (94 g, yield 72%).

The obtained polymer was Mw = 14,000 and Mw / Mn = 1.7. Moreover, it has a repeating unit represented by a following formula (A-3) as a result of < ¹³ > C-NMR analysis, The content rate (molar ratio) of each repeating unit is p1 / p2 / p3 = 70/20 / 10.

<Synthesis Example 4>
Instead of the compound 117g represented by the above formula (L-1), the compound 41g represented by the above formula (L-2), and the compound 5g represented by the above formula (L-3), the above formula (L <Synthesis Example 1> except that the compound 114g represented by -1), the compound 44g represented by the above formula (L-2), and the compound 12g represented by the above formula (L-6) were used. >, A polymer was obtained (100 g, yield 71%).

The obtained polymer was Mw = 13,000 and Mw / Mn = 1.8. Moreover, it has a repeating unit represented by a following formula (A-4) as a result of < ¹³ > C-NMR analysis, The content rate (molar ratio) of each repeating unit is p1 / p2 / p3 = 70/25 / It was 5.

<Synthesis Example 5>
Instead of the compound 117g represented by the above formula (L-1), the compound 41g represented by the above formula (L-2), and the compound 5g represented by the above formula (L-3), the above formula (L -1), the compound 97g, the compound (L-2) 44g, the compound (L-3) 5g, and the compound (L-7). A polymer was obtained in the same manner as in <Synthesis Example 1> except that Compound 29g was used (106 g, yield 71%).

The obtained polymer was Mw = 13,000 and Mw / Mn = 1.7. Moreover, it has a repeating unit represented by a following formula (A-5) as a result of < ¹³ > C-NMR analysis, The content rate (molar ratio) of each repeating unit is p1 / p2 / p3 / p4 = 60 / It was 25/5/10.

<Synthesis Example 6>
Compound 6g represented by formula (L-6), compound 59g represented by formula (L-8), compound 6g represented by formula (L-9), and formula (L-10) A compound solution was prepared by dissolving 34 g of the compound represented by the formula (1) in 100 g of isopropanol and further adding 4.1 g of AIBN. A 500 mL three-necked flask charged with 100 g of isopropanol was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization start time, and the polymerization reaction was carried out for 4 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water to 30 ° C. or less to obtain a polymerization solution. The polymerization liquid was concentrated to 200 g, transferred to a separatory funnel together with 200 g of methanol and 1600 g of n-heptane, and after stirring sufficiently, the lower layer was separated. The lower layer obtained here was concentrated to obtain a polymer (71 g, yield 68%).

The obtained polymer was Mw = 6,900 and Mw / Mn = 1.7. Moreover, as a result of the ¹³ C-NMR analysis, it has a repeating unit represented by the following formula (A-6), and the content (molar ratio) of each repeating unit is p1 / p2 / p3 / p4 = 53 / 5/37/5.

<Synthesis Example 7>
22 g of the compound represented by the above formula (L-7), 44 g of the compound represented by the above formula (L-8), and 41 g of the compound represented by the above formula (L-10) were dissolved in 100 g of isopropanol, and AIBN4 0.7 g was further added to prepare a monomer solution. A 500 mL three-necked flask charged with 100 g of isopropanol was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization start time, and the polymerization reaction was carried out for 4 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water to 30 ° C. or less to obtain a polymerization solution. The polymerization liquid was concentrated to 200 g, transferred to a separatory funnel together with 200 g of methanol and 1600 g of n-heptane, and after stirring sufficiently, the lower layer was separated. The lower layer obtained here was concentrated to obtain a polymer (75 g, yield 70%).

The obtained polymer had Mw = 8,100, Mw / Mn = 1.7, and the residual ratio of the low molecular weight component was 0.04%. Further, ¹³ C-NMR analysis revealed that a repeating unit represented by the following formula (A-7), the content of each repeating unit (molar ratio), p1 / p2 / p3 = 40 /15 / 45.

<Synthesis Example 8>
71 g of the compound represented by the formula (L-11), 170 g of the compound represented by the formula (L-12), and 5 g of the compound represented by the formula (L-13) are dissolved in 200 g of isopropanol. A monomer solution was prepared by further adding 7.4 g of AIBN. A 1000 mL three-necked flask charged with 100 g of isopropanol was purged with nitrogen for 30 minutes, then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization start time, and the polymerization reaction was carried out for 4 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water to 30 ° C. or less to obtain a polymerization solution. The polymerization solution was concentrated to 200 g, transferred to a separatory funnel with 200 g of methanol and 1600 g of n-heptane, sufficiently stirred, and the lower layer was separated. The lower layer obtained here was concentrated to obtain a polymer (165 g, yield 67%).

The obtained polymer was Mw = 6,100 and Mw / Mn = 1.7. Moreover, it has a repeating unit represented by a following formula (A-8) as a result of < ¹³ > C-NMR analysis, The content rate (molar ratio) of each repeating unit is p1 / p2 / p3 = 32/65 / 3.

  Table 1 shows the compositions of the copolymers synthesized in Synthesis Examples 1 to 8.

<Adjustment of radiation-sensitive composition>
Each component (acid generator [B], acid diffusion inhibitor [C], and solvent [other components] constituting the radiation-sensitive composition other than the polymers (A-1) to (A-8) synthesized in the above synthesis example. E]) is shown below.

Acid generator [B]
(B-1): N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide (B-2): N- (10-camphorsulfonyloxy) Succinimide (B-3): 2,4,6-trimethylphenyldiphenylsulfonium 2,4-difluorobenzenesulfonate (B-4): triphenylsulfoniumbenzenesulfonate (B-5): triphenylsulfonium nonafluorobutanesulfonate

Acid diffusion controller [C]
(C-1): 2-phenylbenzimidazole

Solvent [E]
(E-1): Ethyl lactate (E-2): Propylene glycol monomethyl ether acetate (E-3): Ethyl 3-ethoxypropionate

<Examples 1-8 and Comparative Examples 1-3>
The components shown in Table 2 below (where parts are based on mass) were mixed to form a uniform solution, and then filtered through a Teflon (registered trademark) membrane filter having a pore size of 0.2 μm to prepare a composition solution. did.

  Next, each composition solution is spin-coated on a silicon wafer having a step formed by polysilicon as shown in FIG. 1 and then PB is performed at 110 ° C. for 90 seconds to form a resist film having a film thickness of 0.3 μm. Formed. After that, each resist film was exposed using a KrF excimer laser irradiation apparatus NSR-S203B (trade name, manufactured by Nikon Corporation) with a KrF excimer laser (wavelength 248 nm) while changing the exposure amount through the mask pattern. PEB was performed at 110 ° C. for 90 seconds. Thereafter, a 2.38 mass% tetramethylammonium hydroxide aqueous solution was used as a developing solution, developed at 23 ° C. for 60 seconds, washed with water for 30 seconds, and dried to form a resist pattern.

<Evaluation of resist film>
A method for evaluating each resist will be described.

<Sensitivity and scum margin>
First, how to evaluate sensitivity and scum margin will be described with reference to FIGS.

  FIG. 1 is a schematic diagram showing a silicon wafer having a step formed by polysilicon, FIG. 2 is a schematic diagram showing a state in which a resist pattern is formed on the silicon wafer of FIG. 1, and FIG. 3 is a step by polysilicon. It is a schematic diagram which expands and shows the part which and a resist pattern orthogonally cross.

As shown in FIG. 1, a wafer was prepared on a silicon substrate 1 having a height difference of 100 nm, a line width of 90 nm, and a polysilicon step 2 having a space of 180 nm. As shown in FIG. 2, the optimum exposure amount for forming a 180 nm line-and-space pattern (1L1S) of the resist pattern 3 perpendicular to the polysilicon step 2 on this wafer has a one-to-one line width. It was set as the exposure amount, and this optimum exposure amount was defined as sensitivity (mJ / cm ² ). The sensitivity is preferably 15 to 40 (mJ / cm ² ).

  An enlarged view of the resist pattern when exposed at the optimum exposure amount shown in FIG. 2 is shown in FIG. The resist pattern of the scum 4 generated in the exposed portion near the portion where the resist pattern 3 and the step 2 intersect and the width t (nm) of the scum end were measured.

<Shape>
The resist pattern was observed with a CD (Critical Dimension) -scanning electron microscope S-9220 (trade name, manufactured by Hitachi High-Technologies Corporation), and the white edge of the line pattern of the resist pattern when exposed at the optimum exposure amount ( When the chipped edge) was 5 nm or less, it was defined as good, and when it exceeded 5 nm, it was defined as defective.

  The evaluation results of Examples 1 to 8 and Comparative Examples 1 to 3 are shown in Table 2 below together with the compositions.

First, as shown in Table 2, the sensitivity is included in the range of 20 to 40 (mJ / cm ² ) in any of Examples 1 to 8 and Comparative Examples 1 to 3, and good sensitivity is obtained. Indicated.

  Next, when comparing the scum, Comparative Example 1 and Comparative Example 2 were 15 nm and 19 nm, respectively, while Examples 1 to 8 were less than 10 nm. From this, the resist film formed using this composition contains a repeating unit (HS) having a hydroxystyrene structure and a repeating unit (Ac1) that becomes a hydroxystyrene structure by the action of an acid, and the above repeating unit. It has been found that by containing at least one selected from (a1) to (a3), sufficient developer solubility is exhibited even on the substrate side.

  In particular, in Example 1, Example 3, Example 6 and Example 7 in which the polymer having the repeating unit (a3) is provided separately from the polymer not having the repeating unit (a3), the scum Can be suitably suppressed. Thereby, it was suggested that it is preferable in order to suppress generation | occurrence | production of a scum to provide the polymer which has the said repeating unit (a3) as some polymer.

  In Examples 3, 6 and 7 in which the polymer having the repeating unit (a3) further has the repeating unit (HS) and the repeating unit (Ac1), scum is present. There wasn't. This suggested that the repeating unit (a3) containing a polymer copolymerized with the repeating unit (HS) and the repeating unit (Ac1) is particularly preferable for suppressing the occurrence of scum.

Furthermore, apart from the polymer having the repeating unit (a3), the repeating unit (HS) and the repeating unit (Ac1), the repeating unit (HS), the repeating unit (Ac1) and the repeating unit (a1) In Example 7 provided with a polymer having), it was found that the sensitivity was 28 (mJ / cm ² ), which is around the middle of 15 to 40, which is a preferable range. Thus, it was suggested that by providing each polymer having such a combination of repeating units, not only the occurrence of scum can be suitably suppressed, but also the sensitivity becomes a particularly preferable value.

  Regarding the shape, Comparative Example 3 in which the occurrence of scum was suitably suppressed was “bad”, whereas Examples 1 to 8 were all “good”. From this, it was found that the resist pattern has a good shape by having the repeating unit (HS) and the repeating unit (Ac1) in the polymer component.

  DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Level difference, 3 ... Resist pattern, 4 ... Scum, t ... Width of resist pattern edge and scum edge.

Claims (10)

A radiation-sensitive composition comprising a polymer component comprising at least one polymer, a radiation-sensitive acid generator, and a solvent,
As the repeating unit of the polymer component,
At least one of a repeating unit containing a hydroxystyrene structure, and a repeating unit that becomes a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator;
At least one selected from a repeating unit represented by the following general formula (1), a repeating unit represented by the following general formula (2), and a repeating unit represented by the following general formula (3);
A radiation-sensitive composition comprising:
In (Equation (1), ^{R 1} is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, ^{R 2} and ^{R 3} are independently (i) cross, a hydrogen atom, a fluorine atom, 1 to 4 carbon atoms An alkyl group, or a C 1-4 fluoroalkyl group, or (ii) a C 4-20 divalent alicyclic hydrocarbon group containing carbon atoms bonded to each other, or A group obtained by removing two hydrogen atoms from a derivative of an alicyclic hydrocarbon having 4 to 20 carbon atoms, A is a divalent organic group, and B is a single bond or a divalent carbon atom having 1 to 20 carbon atoms. However, any one of R ² and R ³ is a fluorine atom or a fluoroalkyl group, or the above alicyclic structure formed by combining R ² and R ^3. The group which has has a fluorine atom.)
(In Formula (2), R ⁴ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ⁵ is a perfluoroalkyl group having 1 to 10 carbon atoms or 3 to 3 carbon atoms substituted with a fluorine atom. And a monovalent alicyclic hydrocarbon group of 10. D is a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms.)
In (Equation (3), ^{R 6} is a hydrogen atom or an alkyl group of 1 to 5 carbon ^atoms, R ^{7a, R 7b} and ^{R 7c} independently of one another, a hydrogen atom, 1 to 4 fluorine atoms or carbon atoms Provided that any one of R ^{7a to} R ^7c is a fluorine atom or a fluoroalkyl group having 1 to 4 carbon atoms.)   The radiation-sensitive composition according to claim 1, wherein the polymer component includes a repeating unit represented by the general formula (1).   The radiation-sensitive composition according to claim 2, comprising 0.1 to 50 mol% of the repeating unit represented by the general formula (1) with respect to all repeating units of the polymer component. .   The radiation sensitive composition according to any one of claims 1 to 3, wherein the polymer component includes a repeating unit represented by the general formula (3).   5. The radiation-sensitive composition according to claim 4, comprising 0.1 to 30 mol% of the repeating unit represented by the general formula (3) with respect to all repeating units of the polymer component. . The polymer component is
A polymer [A1] containing at least one of a repeating unit having a hydroxystyrene structure and a repeating unit having a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator;
The polymer containing at least 1 sort (s) chosen from the repeating unit represented by the said General formula (1), the repeating unit represented by the said General formula (2), and the repeating unit represented by the said General formula (3) [ A2] (except for the same composition as the polymer [A1]),
The radiation-sensitive composition according to any one of claims 1 to 5, comprising:   The radiation-sensitive composition according to claim 6, wherein the polymer [A1] does not have a repeating unit containing a fluorine atom.   8. The polymer [A2] contains at least one of a repeating unit containing a hydroxystyrene structure and a repeating unit that becomes a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator. The radiation-sensitive composition as described in 1. The polymer component is
At least one of a repeating unit containing a hydroxystyrene structure, and a repeating unit that becomes a hydroxystyrene structure by the action of an acid by the radiation-sensitive acid generator;
At least one selected from the repeating unit represented by the general formula (1), the repeating unit represented by the general formula (2), and the repeating unit represented by the general formula (3);
The radiation-sensitive composition according to claim 1, comprising a polymer containing The radiation-sensitive composition according to any one of claims 1 to 9, wherein the repeating unit represented by the general formula (1) is represented by the following general formula (1-1).
(In Formula (1-1), R ¹ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and R ¹¹ and R ¹² are each independently a fluorine atom or a fluoroalkyl group having 1 to 4 carbon atoms. B is a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms.)