JP6794728B2 - Radiation-sensitive resin composition, resist pattern forming method, polymer and compound - Google Patents

Description

The present invention relates to radiation-sensitive resin compositions, resist pattern forming methods, polymers and compounds.

With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, further miniaturization of resist patterns in the lithography process is required. Therefore, various radiation-sensitive resin compositions are being studied. Such a radiation-sensitive resin composition generates an acid in the exposed portion by irradiating it with exposure light such as far ultraviolet rays such as ArF excimer laser, extreme ultraviolet (EUV), and electron beam, and the catalytic action of this acid causes the exposed portion. And the unexposed portion have a difference in dissolution rate with respect to the developing solution, and a resist pattern is formed on the substrate.

Such a radiation-sensitive resin composition not only has excellent resolution and rectangularity of the cross-sectional shape of the resist pattern, but also has excellent LWR (Line Width Roughness) performance, as well as depth of focus and MEEF (Mask Eror Enhancement Factor) performance. It is also required to obtain a highly accurate pattern with a high yield. In response to this requirement, various structures of the polymer contained in the radiation-sensitive resin composition have been studied, and by having a lactone structure such as a butyrolactone structure and a norbornan lactone structure, the adhesion of the resist pattern to the substrate It is known that these performances can be improved as well as those of JP-A-11-212265 (see JP-A-11-212265, JP-A-2003-5375 and JP-A-2008-833370).

Japanese Unexamined Patent Publication No. 11-21265 Japanese Unexamined Patent Publication No. 2003-5375 Japanese Unexamined Patent Publication No. 2008-833370

However, in the present situation where the refinement of the resist pattern has progressed to the level of the line width of 45 nm or less, the required level of the above performance is further increased, and the above-mentioned conventional radiation-sensitive resin composition satisfies these requirements. I haven't been able to let you. Further, recently, it is required that the shrinkage of the resist film during post-exposure heating (Post Exposure Bake (PEB)) is small and the film shrinkage inhibitory property is excellent, and as a result, the above-mentioned resist performances are further improved. Is required.

The present invention has been made based on the above circumstances, and an object of the present invention is a radiation-sensitive resin having excellent LWR performance, resolution, rectangular cross-sectional shape, depth of focus, MEEF performance, and film shrinkage inhibitory property. It is an object of the present invention to provide a composition, a resist pattern forming method, a polymer and a compound.

（式（１）中、Ｒ^１は、酸素原子を含む環員数３〜２０の１価の環状基である。Ｌ^１は、単結合又は炭素数１〜２０の２価の有機基である。但し、Ｒ^１が単環のラクトン環基の場合、Ｌ^１は単結合である。＊は、上記構造単位（Ｉ）における上記基（Ｉ）以外の部分との結合部位を示す。） The invention made to solve the above problems is a first structural unit (hereinafter, "structural unit (I)") including a group represented by the following formula (1) (hereinafter, also referred to as "group (I)"). A first polymer having (also referred to as "[A] polymer"), a radiation-sensitive acid generator (hereinafter, also referred to as "[B] acid generator"), and a solvent (hereinafter, also referred to as "[B] acid generator"). It is a radiation-sensitive resin composition containing "[C] solvent").

(In the formula (1), R ¹ is a monovalent cyclic group having 3 to 20 ring members containing an oxygen atom. L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms. However, when R ¹ is a monocyclic lactone ring group, L ¹ is a single bond. * Indicates a bond site of the structural unit (I) with a portion other than the group (I).)

Another invention made to solve the above problems includes a step of coating the radiation-sensitive resin composition on one surface of the substrate, a step of exposing a resist film obtained by the coating step, and a step of exposing the resist film obtained by the coating step. This is a resist pattern forming method including a step of developing the exposed resist film.

Yet another invention made to solve the above problems is a polymer having a structural unit containing the above group (I).

（式（ｉ）中、Ｒ^１は、炭素数３〜２０の酸素原子を含む１価の環状基である。Ｌ^１は、
単結合又は炭素数１〜２０の２価の有機基である。Ｒ^４は、重合性炭素−炭素二重結合を含む１価の基である。但し、Ｒ^１が単環のラクトン環基の場合、Ｌ^１は単結合である。Ｌ^４は、単結合又は炭素数１〜２０の２価の有機基である。） Yet another invention made to solve the above problems is a compound represented by the following formula (i) (hereinafter, also referred to as “compound (i)”).

(In formula (i), R ¹ is a monovalent cyclic group containing an oxygen atom having 3 to 20 carbon atoms. L ¹ is
It is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ⁴ is a polymerizable carbon - is a monovalent group containing a carbon double bond. However, when R ¹ is a monocyclic lactone ring group, L ¹ is a single bond. L ⁴ is a single bond or a divalent organic group having 1 to 20 carbon atoms. )

Here, the "cyclic group containing an oxygen atom" means a group containing a ring structure, having an oxygen atom as an atom constituting the ring, or having an oxygen atom bonded to an atom constituting the ring. .. The “monocyclic lactone ring group” refers to a group having one ring (lactone ring) containing a group represented by −O—C (O) − and having no ring other than this lactone ring. .. The "ring member number" refers to the number of atoms constituting the alicyclic structure, the aromatic ring structure, the aliphatic heterocyclic structure and the aromatic heterocyclic structure, and in the case of a polycycle, the number of atoms constituting the polycycle. To say. For example, the naphthalene structure has 10 ring members and the benzofuran structure has 9 ring members. "Organic group" means a group containing at least one carbon atom.

According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, the LWR is small, the resolution is high, and the cross-sectional shape is rectangular while exhibiting excellent depth of focus, MEEF performance, and film shrinkage inhibitory property. An excellent resist pattern can be formed. The polymer of the present invention can be suitably used as a polymer component of the radiation-sensitive resin composition. The compound of the present invention can be suitably used as a monomer of the polymer. Therefore, these can be suitably used for semiconductor device manufacturing, which is expected to be further miniaturized in the future.

<Radiation-sensitive resin composition>
The radiation-sensitive resin composition contains a [A] polymer, a [B] acid generator, and a [C] solvent. The radiation-sensitive resin composition contains, as suitable components, a fluorine atom-containing polymer other than the [D] acid diffusion controller, the [E] [A] polymer (hereinafter, also referred to as “[E] polymer”) and the polymer. It may contain a polymer having a lower fluorine atom content than the [F] [A] polymer and having a structural unit containing an acid dissociative group (hereinafter, also referred to as “[F] polymer”). , Other optional components may be contained as long as the effects of the present invention are not impaired.

The radioactive resin composition may contain only the base polymer as a polymer component, or may contain a water-repellent polymer additive in addition to the base polymer. The "base polymer" refers to a polymer that is the main component of the resist film formed from the radioactive resin composition, and preferably has a weight of 50% by mass or more with respect to the total polymer constituting the resist film. It means coalescence. Further, the "water-repellent polymer additive" is a polymer having a tendency to be unevenly distributed on the surface layer of the resist film formed by being contained in the radioactive resin composition. A polymer having a higher hydrophobicity than a polymer serving as a base polymer tends to be unevenly distributed on the surface layer of the resist film, and can function as a water-repellent polymer additive. By containing the water-repellent polymer additive, the radioactive resin composition can suppress the elution of acid generators and the like from the resist membrane, and the formed resist membrane surface exhibits a high dynamic contact angle. , The surface of the resist film can exhibit excellent drainage characteristics. This makes it possible to enable high-speed scan exposure without separately forming an upper layer film for blocking the surface of the resist film and the immersion medium in the immersion exposure process. When the radioactive resin composition contains a water-repellent additive, the lower limit of the content of the water-repellent polymer additive is preferably 0.1 part by mass with respect to 100 parts by mass of the base polymer. 3 parts by mass is more preferable, and 0.5 parts by mass is further preferable. The upper limit of the content is preferably 20 parts by mass, more preferably 15 parts by mass, and even more preferably 10 parts by mass. The lower limit of the content of the base polymer in the radioactive resin composition is preferably 70% by mass, more preferably 80% by mass, and 85% by mass with respect to the total solid content in the radioactive resin composition. More preferred. The upper limit of the content is, for example, 99% by mass.

In order for the polymer to function well as a water-repellent polymer additive in the radioactive resin composition, the polymer constituting the water-repellent polymer additive is preferably a polymer having a fluorine atom, and the polymer thereof is preferably fluorine. It is more preferable that the atomic content is larger than the fluorine atom content of the base polymer. When the fluorine atom content of the water-repellent polymer additive is larger than the fluorine atom content of the base polymer, the tendency of the water-repellent polymer additive to be unevenly distributed on the surface layer of the formed resist film is increased. , Properties due to the hydrophobicity of the water-repellent polymer additive, such as high drainage of the resist film surface, are more effectively exhibited.

Examples of the polymer component in the radioactive resin composition include (1) a [A] polymer as a base polymer (hereinafter, also referred to as “[A1] polymer”), and (2) a base polymer. [A] polymer and [A] polymer as a water-repellent polymer additive (hereinafter, also referred to as "[A2] polymer"), (3) [A] polymer as a base polymer and water-repellent weight Examples thereof include the case where the [E] polymer as a coalescence additive, the [A] polymer as a (4) water-repellent polymer additive, and the [F] polymer as a base polymer are contained, respectively.
Hereinafter, each component will be described.

<[A] Polymer>
[A] The polymer is a polymer having a structural unit (I). In the radiation-sensitive resin composition, since the polymer [A] has a structural unit (I), LWR performance, resolution, rectangularity of cross-sectional shape, depth of focus, MEEF performance and film shrinkage inhibitory property (hereinafter referred to as , Also referred to as "LWR performance, etc."). The reason why the radiation-sensitive resin composition has the above-mentioned structure and exerts the above-mentioned effect is not always clear, but it can be inferred as follows, for example. That is, the [A] polymer contains a carbonyl group in the group (I) of the structural unit (I) and has many oxygen atoms, and therefore has moderately high rigidity. The radiation-sensitive resin composition has an LWR performance, a resolution, and a cross section because the diffusion length of the acid generated from the [B] acid generator is appropriately shortened due to the rigidity and high polarity of the [A] polymer. The rectangularity of the shape, depth of focus and MEEF performance are improved. Further, in the radiation-sensitive resin composition, it is considered that the polymer [A] has the above-mentioned moderately high rigidity, so that the shrinkage of the resist film at the time of PEB is reduced and the film shrinkage inhibitory property is improved.

[A] The polymer is a structural unit other than the structural unit (I), a structural unit (II) containing an acid dissociative group, and a structural unit (I). It is preferable to have a structural unit (III) containing at least one selected from the group and / or a structural unit (IV) containing a hydroxy group, and other structural units other than the above structural units (I) to (IV). You may have. [A] The polymer may have one or more structural units. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit including the group (I). The group (I) is a group represented by the following formula (1).

In the above formula (1), R ¹ is a monovalent cyclic group having 3 to 20 ring members containing an oxygen atom. L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms. However, when R ¹ is a monocyclic lactone ring group, L ¹ is a single bond. * Indicates a binding site with a portion other than the group (I) in the structural unit (I).

Examples of the monovalent cyclic group having 3 to 20 ring members containing an oxygen atom represented by R ¹ include a polycyclic lactone such as a norbornane lactone-yl group, a cyanonorbornane lactone-yl group, and an oxynorbornane lactone-yl group. Lactone ring groups such as monocyclic lactone ring groups such as ring groups, butyrolactone-yl groups, and valerolactone-yl groups;
Carbonate ring groups such as ethylene carbonate group, propylene carbonate group, butylene carbonate group, vinylene carbonate group;
1,3-Dioxacyclopentane-yl group, 2,2-dimethyl-1,3-dioxacyclopentane-yl group, 1,3-dioxacyclohexane-yl group, 1,3-dioxacyclopentene-yl Group, acetal ring group such as 1,3-dioxacyclohexene-yl group;
Alcoholic hydroxyl group-containing alicyclic groups such as hydroxycyclohexyl group, hydroxycyclohexenyl group, hydroxynorbornyl group, hydroxyadamantyl group;
Phenolic hydroxyl group-containing groups such as hydroxyphenyl group and hydroxynaphthyl group;
Cyclic ether groups such as oxylanyl group, oxetanyl group, oxacyclopentyl group, oxacyclopentenyl group, oxacyclohexyl group, oxacyclohexenyl group;
Examples thereof include oxygen atom-containing aromatic heterocyclic groups such as a furanyl group, a pyranyl group, a chromanyl group, an isochromanyl group, a chromenyl group and a xanthenyl group. Among these, a lactone ring group, a carbonate ring group, an acetal ring group, an alcoholic hydroxyl group-containing alicyclic group and a phenolic hydroxyl group-containing group are preferable, and a lactone ring group, a carbonate ring group, an acetal ring group and an alcoholic hydroxyl group are contained. Groups are more preferred, and lactone ring groups are more preferred.

Examples of the divalent organic group having 1 to 20 carbon atoms represented by L ¹ include a divalent hydrocarbon group having 1 to 20 carbon atoms, and a divalent hydrocarbon group having a divalent value between carbon and carbon. Examples thereof include a group containing a hetero-atom-containing group (α), a divalent hydrocarbon group and a group in which a part or all of the hydrogen atoms of the group (α) are replaced with a monovalent hetero-atom-containing group.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms include a divalent chain hydrocarbon group having 1 to 20 carbon atoms, a divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 6 carbon atoms. Examples thereof include divalent aromatic hydrocarbon groups of ~ 20.

Examples of the divalent chain hydrocarbon group having 1 to 20 carbon atoms include an alkanediyl group such as a methanediyl group, an ethanediyl group, a propanediyl group, and a butanjiyl group;
Arkendiyl groups such as ethendyl groups, propendil groups, butendiyl groups;
Examples thereof include an alkyndiyl group such as an ethyndiyl group, a propindiyl group, and a butindiyl group.

Examples of the divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a divalent monocyclic alicyclic saturated hydrocarbon group such as a cyclopentanediyl group and a cyclohexanediyl group;
Divalent monocyclic alicyclic unsaturated hydrocarbon group such as cyclopentenediyl group and cyclohexenediyl group;
A divalent polycyclic alicyclic saturated hydrocarbon group such as a norbornane diyl group, an adamantandiyl group, and a tricyclodecanediyl group;
Examples thereof include a divalent polycyclic alicyclic unsaturated hydrocarbon group such as a norbornene diyl group and a tricyclodecene diyl group.

Examples of the divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include an arenediyl group such as a benzenediyl group, a toluenediyl group, a xylenediyl group, a naphthalenediyl group, and an anthracendiyl group;
Examples thereof include arenediyl alkanediyl groups such as benzenediylmethanediyl group, benzenediylethanediyl group, naphthalenediylmethanediyl group and anthracenediylmethanediyl group.

Examples of the hetero atom constituting the monovalent and divalent hetero atom-containing groups include an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a silicon atom, a halogen atom and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the divalent heteroatom-containing group include -O-, -CO-, -S-, -CS-, -NR'-, a group in which two or more of these are combined, and the like. R'is a hydrogen atom or a monovalent hydrocarbon group. Of these, —O— is preferred.

Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, amino group and sulfanyl group. Of these, a halogen atom is preferable, and a fluorine atom is more preferable.

As L ¹ , a single bond and a divalent hydrocarbon group are preferable, a single bond and an alkanediyl group are more preferable, a single bond and a methanediyl group are further preferable, and a single bond is particularly preferable.

In the radiation-sensitive resin composition, when R ¹ is a monocyclic lactone ring group, L ¹ is a single bond. When R ¹ is a monocyclic lactone ring group and L ¹ is a divalent organic group, it is considered that the rigidity of the [A] polymer is insufficient, and the LWR performance and the like of the radiation-sensitive resin composition are deteriorated. descend.

Examples of the group (I) include groups represented by the following formulas (I-1) to (I-7) (hereinafter, also referred to as "groups (I-1) to (I-7)"). ..

In the above formulas (I-1) to (I-7), * is synonymous with the above formula (1).

Of these, the groups (I-1) to (I-7) are preferable.

The structural unit (I) is, for example, a structural unit represented by the following formula (1-1) (hereinafter, also referred to as “structural unit (I-1)”) or a structure represented by the following formula (1-2). A unit (hereinafter, also referred to as “structural unit (I-2)”) and the like can be mentioned.

In the above formulas (1-1) and (1-2), Z is the above group (I).
In the above formula (1-1), R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L ² is a divalent organic group having 1 to 20 carbon atoms.
In the above formula (1-2), R ³ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. L ³ is a divalent organic group having 1 to 20 carbon atoms.

The R ^2, from the viewpoint of copolymerizability of the monomer giving the structural unit (I-1), preferably a hydrogen atom or a methyl group, more preferably a methyl group.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ³ include a group in which one hydrogen atom is added to the group exemplified as the divalent organic group of L ^{1 in} the above formula (1). Can be mentioned. The R ^3, organic group, more preferably a hydrocarbon group, more preferably a chain-like hydrocarbon group, an alkanediyl group is particularly preferred.

Examples of the divalent organic group having 1 to 20 carbon atoms represented by L ² and L ³ include the same groups as those exemplified as the divalent organic group of L ^{1 in} the above formula (1). .. As L ² and L ³ , a hydrocarbon group is preferable, an alkandiyl group, a monocyclic alicyclic saturated hydrocarbon group, a polycyclic alicyclic saturated hydrocarbon group and an arenediyl group are more preferable, and a methanediyl group and an ethanediyl group are more preferable. More preferred are groups, cyclohexanediyl groups, adamantandiyl groups and benzenediyl groups.

The structural unit (I-1) is, for example, a structural unit represented by the following formulas (1-1-1) to (1-1-10) (hereinafter, “structural unit (I-1-1) to (I-1)”. -11) ”) and the like. The structural unit (I-2) is, for example, a structural unit represented by the following formula (1-2-1) or formula (1-2-2) (hereinafter, “structural unit (I-2-1),” (. I-2-2) ”) and the like.

In the above formulas (1-1-1) to (1-1-10), R ² has the same meaning as the above formula (1-1).
In the above formulas (1-2-1) and (1-2-2), R ³ has the same meaning as the above formula (1-2).

As the lower limit of the content ratio of the structural unit (I), 1 mol% is preferable, 3 mol% is more preferable, 5 mol% is further preferable, and 8 mol is more preferable with respect to all the structural units constituting the polymer [A]. % Is particularly preferable. The upper limit of the content ratio of the structural unit (I) is preferably 80 mol%, more preferably 50 mol%, further preferably 30 mol%, and particularly preferably 20 mol%. By setting the content ratio of the structural unit (I) within the above range, the LWR performance and the like of the radiation-sensitive resin composition can be further improved.

Examples of the compound that gives the structural unit (I) include compound (i) and the like. Compound (i) is represented by the following formula (i).

In the above formula (i), R ¹ is a monovalent cyclic group containing an oxygen atom having 3 to 20 carbon atoms. L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ⁴ is a polymerizable carbon - is a monovalent group containing a carbon double bond. However, when R ¹ is a monocyclic lactone ring group, L ¹ is a single bond. L ⁴ is a single bond or a divalent organic group having 1 to 20 carbon atoms.

Examples of the group containing a polymerizable carbon-carbon double bond in the monovalent group of R ⁴ include a (meth) acryloyl group, a vinyl group, a styryl group and the like.

Examples of the compound (i) include compounds represented by the following formulas (i1) to (i12) (hereinafter, also referred to as “compounds (i1) to (i12)”).

In the above formulas (i1) to (i10), R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.
In the above formula (i11) and (i12), ^{R 3} is a monovalent organic group hydrogen atom or a C 1-20.

Of these, compounds (i1) to (i12) are preferable.

Compound (i), for example ^{R 4} is R ⁴ in the formula (i) ^'-COO- (R ^4' are polymerizable carbon - a monovalent group containing a carbon double bond) in which formula (i ' In the case of the compound represented by), it can be easily synthesized with good yield according to the following scheme.

In the above scheme, R ¹ is a monovalent cyclic group containing an oxygen atom having 3 to 20 carbon atoms. L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms. However, when R ¹ is a monocyclic lactone ring group, L ¹ is a single bond. L ⁴ is a single bond or a divalent organic group having 1 to 20 carbon atoms. Y ¹ and Y ² are independent halogen atoms. R 4 ^'is polymerizable carbon - is a monovalent group containing a carbon double bond.

Examples of the halogen atom represented by Y ¹ and Y ² include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom and the like. Among these, a chlorine atom and a bromine atom are preferable, and a chlorine atom is more preferable.

The halogenic acid haloester represented by the above formula (i'-a) and the hydroxy compound represented by the above formula (i'-b) are reacted in the presence of a base such as pyridine in a solvent such as methylene chloride. By doing so, a compound represented by the above formula (i'-c) can be obtained. This compound (i'-c) and the carboxylic acid represented by the above formula (i'-d) are mixed in a solvent such as N, N-dimethylformamide in the presence of salts such as potassium carbonate and potassium iodide. By reacting, compound (i') can be obtained.

Compound (i') can be isolated by appropriately purifying the obtained product by column chromatography, recrystallization, distillation or the like.

Compound (i) other than compound (i') can also be synthesized by the same method as described above.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociative group. The "acid dissociative group" is a group that replaces a hydrogen atom such as a carboxy group or a hydroxy group, and means a group that dissociates by the action of an acid. Since the [A] polymer has the structural unit (II) in addition to the structural unit (I), the radiation-sensitive resin composition has higher sensitivity, and as a result, the LWR performance and the like can be further improved. ..

Examples of the structural unit (II) include a structural unit represented by the following formula (2) (hereinafter, also referred to as “structural unit (II-1)”) and a structural unit including an acetal structure (hereinafter, “structural unit (II-1)”). -2) ”) and the like. The polymer [A] may have one or more structural units (II-1) and (II-2), respectively. [A] The polymer may have both a structural unit (II-1) and a structural unit (II-2). Hereinafter, the structural unit (II-1) and the structural unit (II-2) will be described.

(Structural unit (II-1))
The structural unit (II-1) is a structural unit represented by the following formula (2). The group represented by −CR ¹⁵ R ¹⁶ R ¹⁷ in the following formula (2) is an acid dissociative group.

In the above formula (2), R ¹⁴ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹⁵ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ¹⁶ and R ¹⁷ are independently monovalent hydrocarbon groups having 1 to 20 carbon atoms, or 3 to 3 carbon atoms composed of carbon atoms in which these groups are combined with each other and bonded to each other. Represents 20 alicyclic structures.

The R ^14, from the viewpoint of copolymerizability of the monomer giving the structural unit (II-1), preferably a hydrogen atom or a methyl group, more preferably a methyl group.

As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹⁵ , R ¹⁶ and R ¹⁷ , for example, a group obtained by adding one hydrogen atom to the divalent hydrocarbon group exemplified as L ¹ above. And so on.

Examples of the alicyclic structure having 3 to 20 carbon atoms in which the groups of R ¹⁶ and R ¹⁷ are combined with each other and together with the carbon atoms to which they are bonded include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, and a cyclopentene structure. , Cyclohexene structure, norbornane structure, adamantane structure and the like.

The structural unit (II-1) is a structural unit represented by the following formulas (2-1) to (2-5) (hereinafter, “structural unit (II-1-1) to (II-1-5)). ”) Is preferable.

In the above formulas (2-1) to (2-5), R ^{14 to} R ¹⁷ have the same meaning as the above formula (2). i and j are each independently an integer of 1 to 4.

Examples of the structural unit (II-1) include a structural unit represented by the following formula.

In the above formula, R ¹⁴ is synonymous with the above formula (2).

As the structural unit (II-1), structural units (II-1-1) to (II-1--3) are preferable, and structural units derived from 1-alkylcyclopentane-1-yl (meth) acrylate, 2 More preferred are structural units derived from -alkyl-adamantan-2-yl (meth) acrylate and structural units derived from 2- (cycloalkane-1-yl) propan-2-yl (meth) acrylate.

(Structural unit (II-2))
The structural unit (II-2) is a structural unit including an acetal structure. Examples of the group containing an acetal structure include a group represented by the following formula (X) (hereinafter, also referred to as “group (X)”). The group (X) is decomposed by the action of an acid to produce * -OH, R ^{X RY} C = O and R ^Z OH. In the group (X), -C ( ^RX ) ( ^RY ) (OR ^Z ) is an acid dissociative group.

In the above formula (X), ^RX and ^RY are independently hydrogen atoms or monovalent hydrocarbon groups having 1 to 20 carbon atoms. R ^Z is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^W is a divalent hydrocarbon group of a single bond or a C 1-20. R ^{X, R Y,} more than two of R ^Z and R ^W may also form a ring structure of ring members 3 to 20 together with the carbon atom or chain of atoms aligned they are bound to each other. * Indicates a binding site with a portion of the structural unit (II-2) other than the above group (X).

R ^X, examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by ^{R Y} and ^{R Z,} for example, such as the same group and a monovalent organic group exemplified having 1 to 20 carbon atoms as ^{R 3} is Can be mentioned.

As ^RX and ^RY , a hydrogen atom and a chain hydrocarbon group are preferable, a hydrogen atom and an alkyl group are more preferable, and a hydrogen atom and a methyl group are further preferable. As R ^Z , a chain hydrocarbon group is preferable, an alkyl group is more preferable, and a methyl group is particularly preferable.

The R ^W, a single bond or a chain hydrocarbon group, more preferably a chain-like hydrocarbon group, more preferably an alkanediyl group, methylene bridge are particularly preferred.

^{R X,} R Y, as the ring structure ring members 3 to 20 or more two forms of ^{R Z} and ^{R W,} for example, 1,3-dioxacyclopentane structure like 1,3 Jiokisashikuro An alkane structure and the like can be mentioned.

As the group (X), a group containing a cyclic acetal structure is preferable, and a group containing a 2,2-dimethyl-1,3-dioxacyclopentane structure is more preferable.

When the [A] polymer has a structural unit (II), the lower limit of the content ratio of the structural unit (II) is preferably 10 mol%, preferably 20 mol%, based on all the structural units constituting the [A] polymer. More preferably mol%, more preferably 30 mol%. The upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content ratio of the structural unit (II) in the above range, the sensitivity of the radiation-sensitive resin composition can be further improved, and as a result, the LWR performance and the like can be further improved.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. By further having the structural unit (III), the polymer [A] can further adjust its solubility in a developing solution, and as a result, further improve the LWR performance and the like of the radiation-sensitive resin composition. be able to. In addition, the adhesion between the resist pattern formed from the radiation-sensitive resin composition and the substrate can be improved.

Examples of the structural unit (III) include a structural unit represented by the following formula.

In the above formula, ^RL1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

Among these, the structural unit (III) is preferably a structural unit containing a norbornane lactone structure, a structural unit containing a γ-butyrolactone structure, a structural unit containing an ethylene carbonate structure, and a structural unit containing a norbornane sultone structure.

When the [A] polymer has a structural unit (III), the lower limit of the content ratio of the structural unit (III) is preferably 10 mol%, preferably 20 mol%, based on all the structural units constituting the [A] polymer. More preferably mol%, more preferably 25 mol%. The upper limit of the content ratio is preferably 70 mol%, more preferably 60 mol%, still more preferably 55 mol%. By setting the content ratio in the above range, the LWR performance and the like of the radiation-sensitive resin composition can be further improved. In addition, the adhesion of the resist pattern to the substrate can be further improved.

[Structural unit (IV)]
The structural unit (IV) is a structural unit containing a hydroxy group. Examples of the hydroxy group include an alcoholic hydroxy group and a phenolic hydroxy group. By further having the structural unit (IV), the polymer [A] can further adjust its solubility in a developing solution, and as a result, further improve the LWR performance and the like of the radiation-sensitive resin composition. be able to. In addition, the adhesion between the resist pattern formed from the radiation-sensitive resin composition and the substrate can be improved. When the structural unit (IV) contains a phenolic hydroxy group, the radiation-sensitive resin composition can further increase the sensitivity in KrF exposure, EUV exposure, electron beam exposure and the like.

Examples of the structural unit (IV) include a structural unit represented by the following formula.

In the above formula, ^RL2 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

As the structural unit (IV), a structural unit derived from hydroxystyrene and a structural unit derived from 3-hydroxyadamantane-1-yl (meth) acrylate are preferable.

When the [A] polymer has a structural unit (IV), the lower limit of the content ratio of the structural unit (IV) is preferably 1 mol% with respect to all the structural units constituting the [A] polymer. More preferably mol%. The upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and even more preferably 30 mol%.

The structural unit containing a phenolic hydroxy group can be formed, for example, by hydrolyzing a polymer obtained by using a monomer such as acetoxystyrene in the presence of a base such as triethylamine.

<Other structural units>
[A] The polymer may have other structural units other than the above structural units (I) to (IV). Examples of other structural units include structural units containing a carboxy group, a cyano group, a nitro group, a sulfonamide group or a combination thereof, a structural unit containing a non-dissociable hydrocarbon group, and the like. When the [A] polymer has these structural units, the upper limit of the content ratio of these structural units is preferably 20 mol% and 10 mol% with respect to all the structural units constituting the [A] polymer. Is more preferable.

When the [A] polymer is a [A2] polymer, the [A] polymer preferably has a structural unit containing a fluorine atom. Examples of the structural unit containing a fluorine atom include a structural unit (Ea) and a structural unit (Eb) in the [E] polymer described later. When the [A] polymer has these structural units, the lower limit of the content ratio of these structural units is preferably 1 mol% and 5 mol% with respect to all the structural units constituting the [A] polymer. Is more preferable, 10 mol% is further preferable, and 20 mol% is particularly preferable. The upper limit of the structural unit is preferably 80 mol%, more preferably 70 mol%, still more preferably 50 mol%.

The lower limit of the content of the polymer [A] is preferably 70% by mass, more preferably 80% by mass, based on the total solid content of the radiation-sensitive resin composition (total of the components other than the [C] solvent). It is preferable, and 85% by mass is more preferable. The upper limit of the content is preferably 99% by mass, more preferably 95% by mass. [A] The polymer may contain one kind or two or more kinds.

<[A] Polymer synthesis method>
The polymer [A] can be synthesized, for example, by polymerizing a monomer giving each structural unit in an appropriate solvent using a radical polymerization initiator or the like.

Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), and 2,2'-azobis (2-cyclopropylpro). Pionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate and other azo radical initiators; benzoyl peroxide, t-butyl hydroperoxide, Examples thereof include peroxide-based radical initiators such as cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferable, and AIBN is more preferable. These radical polymerization initiators can be used alone or in admixture of two or more.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylenedibromid, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, methyl propionate;
Ketones such as acetone, butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol and 4-methyl-2-pentanol. The solvent used for these polymerizations may be used alone or in combination of two or more.

The lower limit of the reaction temperature in the polymerization is preferably 40 ° C., more preferably 50 ° C. The upper limit of the reaction temperature is preferably 150 ° C., more preferably 120 ° C. The lower limit of the reaction time in the polymerization is preferably 1 hour, more preferably 2 hours. The upper limit of the reaction time is preferably 48 hours, more preferably 24 hours.

[A] The lower limit of the polystyrene-equivalent weight average molecular weight (Mw) of the polymer by gel permeation chromatography (GPC) is preferably 1,000, more preferably 2,000, still more preferably 3,000, and 5, 000 is particularly preferable. As the upper limit of the Mw, 50,000 is preferable, 30,000 is more preferable, 20,000 is further preferable, and 15,000 is particularly preferable. By setting the Mw of the polymer in the above range, the coatability of the radiation-sensitive resin composition can be improved, and as a result, the LWR performance and the like can be further improved.

[A] As the upper limit of the ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer by GPC, 5 is preferable, 3 is more preferable, 2 is further preferable, and 1.7 is particularly preferable. .. The lower limit of the above ratio is usually 1, preferably 1.1.

The Mw and Mn of the polymer in the present specification are values measured by gel permeation chromatography (GPC) under the following conditions.
GPC column: Tosoh's "G2000HXL" 2 pieces, "G3000HXL" 1 piece and "G4000HXL" 1 piece Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.)
Flow velocity: 1.0 mL / min Sample concentration: 1.0 mass%
Sample injection volume: 100 μL
Detector: Differential Refractometer Standard Material: Monodisperse Polystyrene

<[B] Acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. The generated acid dissociates the acid dissociative groups of the [A] polymer and the like to generate carboxy groups, hydroxy groups, etc., and the solubility of the [A] polymer in the developing solution changes. A resist pattern can be formed from the sex resin composition. As the content form of the [B] acid generator in the radiation-sensitive resin composition, even the form of a low molecular weight compound (hereinafter, also referred to as “[B] acid generator”) is incorporated as a part of the polymer. It may be in a form or both of these forms.

[B] Examples of the acid generator include onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds and the like.

Examples of the onium salt compound include sulfonium salt, tetrahydrothiophenium salt, iodonium salt, phosphonium salt, diazonium salt, pyridinium salt and the like.

Specific examples of the [B] acid generator include the compounds described in paragraphs [0080] to [0113] of JP-A-2009-134808.

[B] Examples of the acid generated from the acid generator include sulfonic acid, imic acid, amic acid, methidoic acid, phosphinic acid, carboxylic acid and the like. Of these, sulfonic acid, imidic acid, amidoic acid and methidoic acid are preferable.

Examples of the [B] acid generator include a compound represented by the following formula (4) (hereinafter, also referred to as “[B1] acid generator”).

In the formula (4), A ^- is a monovalent acid anion, a monovalent imide anion, a monovalent amide anion or a monovalent methide anion. Z ⁺ is a monovalent radiation-sensitive onium cation.

As the [B1] acid generator, when A ⁻ in the above formula (4) is a sulfonic acid anion (hereinafter, also referred to as “[B1a] acid generator”), sulfonic acid is generated. A ^- is the case of the imide anion (hereinafter, also referred to as "[B1b] acid generator"), imide acid produced. A ^- is the case of the amide anion (hereinafter, also referred to as "[B1c] acid generator"), an amide acid occurs. A ^- is the case of the methide anion (hereinafter, also referred to as "[B1d] acid generator"), methide acid is generated.

Examples of the [B1a] acid generator include a compound represented by the following formula (4-1) (hereinafter, also referred to as “compound (4-1)”). [B1] Since the acid generator has the following structure, the acid generated by exposure is diffused in the resist film due to the interaction between the structural unit (I) and the structural unit (II) of the polymer component [A]. It is considered that the length is more appropriately shortened, and as a result, the LWR performance and the like of the radiation-sensitive resin composition can be further improved.

In the above formula (4-1), R ^p1 is a monovalent group containing a ring structure having 6 or more ring members. R ^p2 is a divalent linking group. R ^p3 and R ^p4 are independently hydrogen atoms, fluorine atoms, monovalent hydrocarbon groups having 1 to 20 carbon atoms, or monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms. R ^p5 and R ^p6 are independently fluorine atoms or monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms. n ^p1 is an integer from 0 to 10. n ^p2 is an integer from 0 to 10. n ^p3 is an integer from 0 to 10. However, n ^p1 + n ^p2 + n ^p3 is 1 or more and 30 or less. When n ^p1 is 2 or more, a plurality of R ^p2s may be the same or different. When n ^p2 is 2 or more, the plurality of R ^p3s may be the same or different, and the plurality of R ^p4s may be the same or different. When n ^p3 is 2 or more, the plurality of R ^p5s may be the same or different, and the plurality of R ^p6s may be the same or different. Z ⁺ is synonymous with the above equation (4).

Examples of the monovalent group including a ring structure having 6 or more ring members represented by R ^p1 include a monovalent group including an alicyclic structure having 6 or more ring members and an aliphatic heterocyclic structure having 6 or more ring members. Examples thereof include a monovalent group, a monovalent group containing an aromatic ring structure having 6 or more ring members, and a monovalent group containing an aromatic heterocyclic structure having 6 or more ring members.

Examples of the alicyclic structure having 6 or more ring members include a monocyclic saturated alicyclic structure such as a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, and a cyclododecane structure;
Monocyclic unsaturated alicyclic structures such as cyclohexene structure, cycloheptene structure, cyclooctene structure, cyclodecene structure;
Polycyclic saturated alicyclic structures such as norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure;
Examples thereof include a polycyclic unsaturated alicyclic structure such as a norbornene structure and a tricyclodecene structure.

Examples of the aliphatic heterocyclic structure having 6 or more ring members include lactone structures such as hexanolactone structure and norbornane lactone structure;
Sultone structures such as hexanosultone structure and norbornane sultone structure;
Oxygen atom-containing heterocyclic structure such as oxacycloheptane structure and oxanorbornane structure;
Nitrogen atom-containing heterocyclic structure such as azacyclohexane structure and diazabicyclooctane structure;
Examples thereof include a sulfur atom-containing heterocyclic structure such as a thiacyclohexane structure and a thianorbornane structure.

Examples of the aromatic ring structure having 6 or more ring members include a benzene structure, a naphthalene structure, a phenanthrene structure, an anthracene structure and the like.

Examples of the aromatic heterocyclic structure having 6 or more ring members include an oxygen atom-containing heterocyclic structure such as a pyran structure, a benzofuran structure, and a benzopyran structure;
Examples thereof include a nitrogen atom-containing heterocyclic structure such as a pyridine structure, a pyrimidine structure, and an indole structure.

As the lower limit of the number of ring members of the ring structure of R ^p1 , 7 is preferable, 8 is more preferable, 9 is further preferable, and 10 is particularly preferable. As the upper limit of the number of ring members, 15 is preferable, 14 is more preferable, 13 is further preferable, and 12 is particularly preferable. By setting the number of ring members in the above range, the diffusion length of the above-mentioned acid can be further appropriately shortened, and as a result, the LWR performance and the like of the radiation-sensitive resin composition can be further improved.

A part or all of the hydrogen atom of the ring structure of R ^p1 may be substituted with a substituent. Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group and acyl group. Examples thereof include an asyloxy group. Of these, a hydroxy group is preferable.

As R ^p1 , a monovalent group containing an alicyclic structure having 6 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members are preferable, and 1 including an alicyclic structure having 9 or more ring members. A valent group and a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members are more preferable, and an adamantyl group, a hydroxyadamantyl group, a norbornanelactone-yl group, a norbornane sulton-yl group and a 5-oxo-4-oxa A tricyclo [4.3.1.1 ^3,8 ] undecane-yl group is more preferred, and an adamantyl group is particularly preferred.

Examples of the divalent linking group represented by R ^p2 include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, and a divalent hydrocarbon group. Among these, a carbonyloxy group, a sulfonyl group, an alkanediyl group and a divalent alicyclic saturated hydrocarbon group are preferable, a carbonyloxy group and a divalent alicyclic saturated hydrocarbon group are more preferable, and a carbonyloxy group is more preferable. And norbornandyl groups are more preferred, and carbonyloxy groups are particularly preferred.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 include an alkyl group having 1 to 20 carbon atoms. Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 include a fluorinated alkyl group having 1 to 20 carbon atoms. As R ^p3 and R ^p4 , a hydrogen atom, a fluorine atom and a fluorinated alkyl group are preferable, a fluorine atom and a perfluoroalkyl group are more preferable, and a fluorine atom and a trifluoromethyl group are further preferable.

Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p5 and R ^p6 include a fluorinated alkyl group having 1 to 20 carbon atoms. As R ^p5 and R ^p6 , a fluorine atom and a fluorinated alkyl group are preferable, a fluorine atom and a perfluoroalkyl group are more preferable, a fluorine atom and a trifluoromethyl group are further preferable, and a fluorine atom is particularly preferable.

As n ^p1 , an integer of 0 to 5 is preferable, an integer of 0 to 3 is more preferable, an integer of 0 to 2 is further preferable, and 0 and 1 are particularly preferable.

As n ^p2 , an integer of 0 to 5 is preferable, an integer of 0 to 2 is more preferable, 0 and 1 are further preferable, and 0 is particularly preferable.

As the lower limit of n ^p3 , 1 is preferable, and 2 is more preferable. By setting n ^p3 to 1 or more, the strength of the acid generated from the compound (4-1) can be increased, and as a result, the LWR performance and the like of the radiation-sensitive resin composition can be further improved. As the upper limit of n ^p3 , 4 is preferable, 3 is more preferable, and 2 is further preferable.

As the lower limit of n ^p1 + n ^p2 + n ^p3 , 2 is preferable, and 4 is more preferable. As the upper limit of n ^p1 + n ^p2 + n ^p3 , 20 is preferable, and 10 is more preferable.

Examples of the monovalent radiation-sensitive onium cation represented by Z ⁺ include cations represented by the following formulas (Z-1) to (Z-3) (hereinafter, "cations (Z-1) to (Z-)". 3) ”) and the like.

In the above formula (Z-1), R ^a1 , R ^a2, and R ^a3 are independently substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms, and substituted or unsubstituted aromatic groups having 6 to 12 carbon atoms, respectively. family hydrocarbon group, two or more are combined with each other configured ring structure of either a -OSO ₂ -R ^P or _-SO 2 -R ^Q, or their groups. Here, ^RP and ^RQ are independently substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms, substituted or unsubstituted alkyl group having 5 to 25 carbon atoms, or substituted or non-substituted alkyl groups. It is a substituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are independently integers of 0 to 5. R ^a1 to R ^a3 and when ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{to R a3} and ^{R P} and ^{R Q} may be the same as or different from each other.

In the above formula (Z-2), ^Ra4 is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms. k4 is an integer from 0 to 7. If R ^a4 is plural, the plurality of R ^a4 may be the same or different, and plural R ^a4 may represent a constructed ring aligned with each other. R ^a5 is a substituted or unsubstituted alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. k5 is an integer from 0 to 6. If R ^a5 is plural, the plurality of R ^a5 may be the same or different, and plural R ^a5 may represent a keyed configured ring structure. r is an integer from 0 to 3. ^Ra6 is a single bond or a divalent organic group having 1 to 20 carbon atoms. t is an integer from 0 to 2.

In the above formula (Z-3), R ^a7 and R ^a8 are independently substituted or unsubstituted alkyl groups having 1 to 12 carbon atoms and substituted or unsubstituted aromatic hydrocarbons having 6 to 12 carbon atoms, respectively. Represents a ring structure that is a group, -OSO _2- ^RR or -SO _2- ^RS , or is composed of two or more of these groups combined with each other. R ^R and R ^S are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted C 5-25 alicyclic hydrocarbon group, or a substituted or unsubstituted carbon It is an aromatic hydrocarbon group having a number of 6 to 12. k6 and k7 are independently integers of 0 to 5. R ^{a7, R} a8, ^R when ^R and ^{R S} is plural respective plurality of ^{R a7,} R a8, ^{R R} and ^{R S} may be the same as or different from each other.

Examples of the alkyl group represented by R ^{a1 to} R ^a3 , R ^a4 , R ^a5 , R ^a7 and R ^a8 include a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group and an n-butyl group;
Examples thereof include branched alkyl groups such as i-propyl group, i-butyl group, sec-butyl group and t-butyl group.

Examples of the aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^a4 and R ^a5 include an aryl group such as a phenyl group, a tolyl group, a xsilyl group, a mesityl group and a naphthyl group;
Examples thereof include an aralkyl group such as a benzyl group and a phenethyl group.

Examples of the aromatic hydrocarbon group represented by R ^a4 and R ^a5 include a phenyl group, a tolyl group, a benzyl group and the like.

Examples of the divalent organic group represented by R ^a6 include a group similar to L ^{1 of the} above formula (1).

Examples of the substituent that replaces the hydrogen atom of the alkyl group and the aromatic hydrocarbon group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, nitro group and alkoxy. Examples thereof include a group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an asyloxy group and the like. Of these, a halogen atom is preferable, and a fluorine atom is more preferable.

R ^{a1 to} R ^a3 , R ^a4 , R ^a5 , R ^a7 and R ^a8 include an unsubstituted alkyl group, a fluorinated alkyl group, an unsubstituted monovalent aromatic hydrocarbon group, -OSO _2- R "and -SO _2- R "is preferable, fluorinated alkyl groups and unsubstituted monovalent aromatic hydrocarbon groups are more preferable, and fluorinated alkyl groups are even more preferable. Here, R "is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

As k1, k2 and k3 in the formula (Z-1), integers of 0 to 2 are preferable, 0 and 1 are more preferable, and 0 is further preferable. As k4 in the formula (Z-2), an integer of 0 to 2 is preferable, 0 and 1 are more preferable, and 1 is further preferable. As k5, an integer of 0 to 2 is preferable, 0 and 1 are more preferable, and 0 is further preferable. As r, 2 and 3 are preferable, and 2 is more preferable. As t, 0 and 1 are preferable, and 0 is more preferable. As k6 and k7 in the formula (Z-3), integers of 0 to 2 are preferable, 0 and 1 are more preferable, and 0 is further preferable.

Among these, cation (Z-1) and cation (Z-2) are preferable as Z ⁺ , and triphenylsulfonium cation and 4-butoxynaphthalene-1-yltetrahydrothiophenium cation are more preferable.

Examples of the [B1a] acid generator include compounds represented by the following formulas (4-1-1) to (4-1-15) (hereinafter, "Compounds (4-1-1) to (4-1-1)" to (4-1-1). 15) ”) and the like. [B1b] Examples of the acid generator include compounds represented by the following formulas (4-2-1) to (4-2-3) (hereinafter, "compounds (4-2-1) to (4-2-2)". 3) ”) and the like. Examples of the [B1c] acid generator include compounds represented by the following formulas (4-3-1) to (4-3-2) (hereinafter, "Compounds (4-3-1) to (4-3-2)". 2) ”) and the like. Examples of the [B1d] acid generator include compounds represented by the following formulas (4-4-1) to (4-4-2) (hereinafter, "Compounds (4-4-1) to (4--4-2)". 2) ”) and the like.

The above formulas (4-1-1) to (4-1-15), (4-2-1) to (4-2-3), (4-3-1) to (4-3-2) and In (4-4-1) to (4-4-2), Z ⁺ is a monovalent onium cation.

As the [B1] acid generator, the [B1a] acid generator is preferable, and the compounds (4-1-1), (4-1-2), (4-1-11) and (4-1-12) Is more preferable.

[B1] As the acid generator, an onium salt compound is preferable, a sulfonium salt and a tetrahydrothiophenium salt are more preferable, and a triphenylsulfonium salt and a 4-butoxynaphthalene-1-yltetrahydrothiophenium salt are further preferable.

Further, as the [B] acid generator, a polymer in which the structure of the acid generator such as a polymer having a structural unit represented by the following formula (4-1') is incorporated as a part of the polymer is also preferable. ..

In the above formula (4-1'), R ^p7 is a hydrogen atom or a methyl group. L ⁴ is a single bond or -COO- or divalent carbonyloxy hydrocarbon group. R ^p8 is a fluorinated alkanediyl group having 1 to 10 carbon atoms. Z ⁺ is synonymous with the above equation (4).

As R ^p7 , a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable, from the viewpoint of copolymerizability of the monomer giving the structural unit represented by the above formula (4-1').

The L ^4, preferably a divalent carbonyloxy hydrocarbon group, a carbonyl oxy alkane diyl group and a carbonyl alkanediyl arene diyl group are more preferable.

As R ^p8 , a fluorinated alkanediyl group having 1 to 4 carbon atoms is preferable, a perfluoroalkanediyl group having 1 to 4 carbon atoms is more preferable, and a hexafluoropropanediyl group is further preferable.

When the [B] acid generator is a [B] acid generator, the lower limit of the content of the [B] acid generator is preferably 0.1 part by mass with respect to 100 parts by mass of the [A] polymer component. 1, 1 part by mass is more preferable, 4 parts by mass is further preferable, and 7 parts by mass is particularly preferable. The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, further preferably 30 parts by mass, and particularly preferably 25 parts by mass. [B] By setting the content of the acid generator in the above range, the sensitivity and developability of the radiation-sensitive resin composition can be improved, and as a result, the LWR performance and the like can be further improved. [B] The acid generator can contain one kind or two or more kinds.

<[C] Solvent>
The solvent [C] is not particularly limited as long as it is a solvent capable of dissolving or dispersing at least the [A] polymer, the [B] acid generator, and the [D] acid diffusion controller contained if desired.

Examples of the [C] solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents and the like.

Examples of the alcohol solvent include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol;
An alicyclic monoalcoholic solvent having 3 to 18 carbon atoms such as cyclohexanol;
Multivalent alcohol solvent with 2 to 18 carbon atoms such as 1,2-propylene glycol;
Examples thereof include a polyhydric alcohol partial ether solvent having 3 to 19 carbon atoms such as propylene glycol monomethyl ether.

Examples of the ether solvent include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether;
Cyclic ether solvent such as tetrahydrofuran and tetrahydropyran;
Examples thereof include aromatic ring-containing ether solvents such as diphenyl ether and anisole.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone, ethyl-n-butyl ketone, methyl-n-hexyl ketone, and the like. Chain ketone solvents such as di-iso-butyl ketone and trimethylnonanone:
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone:
Examples thereof include 2,4-pentanedione, acetonylacetone and acetophenone.

Examples of the amide solvent include cyclic amide solvents such as N, N'-dimethylimidazolidinone and N-methylpyrrolidone;
Examples thereof include chain amide solvents such as N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide and N-methylpropionamide.

Examples of the ester solvent include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate;
Polyhydric alcohol carboxylate solvent such as propylene glycol acetate;
Polyhydric alcohol partial ether carboxylate solvent such as propylene glycol monomethyl ether acetate;
Polyvalent carboxylic acid diester solvent such as diethyl oxalate;
Examples thereof include carbonate solvents such as dimethyl carbonate and diethyl carbonate.

Examples of the hydrocarbon solvent include an aliphatic hydrocarbon solvent having 5 to 12 carbon atoms such as n-pentane and n-hexane;
Examples thereof include aromatic hydrocarbon solvents having 6 to 16 carbon atoms such as toluene and xylene.

Among these, ester-based solvents and ketone-based solvents are preferable, polyhydric alcohol partial ether carboxylate-based solvents and cyclic ketone-based solvents are more preferable, and propylene glycol acetate monomethyl ether and cyclohexanone are even more preferable. [C] The solvent can contain one kind or two or more kinds.

<[D] Acid diffusion controller>
The radiation-sensitive resin composition may contain the [D] acid diffusion controller, if necessary. The [D] acid diffusion controller has the effect of controlling the diffusion phenomenon of the acid generated from the [B] acid generator in the resist film by exposure and suppressing an unfavorable chemical reaction in the non-exposed region. In addition, the storage stability of the radiation-sensitive resin composition is improved, and the resolution as a resist is further improved. Further, it is possible to suppress the change in the line width of the resist pattern due to the fluctuation of the leaving time from the exposure to the development process, and it is possible to obtain a radiation-sensitive resin composition having excellent process stability. As the content form of the [D] acid diffusion control body in the radiation-sensitive resin composition, even in the form of a free compound (hereinafter, appropriately referred to as “[D] acid diffusion control agent”), it is incorporated as a part of the polymer. Or both of these forms.

[D] As the acid diffusion control agent, for example, a compound represented by the following formula (B) (hereinafter, also referred to as “nitrogen-containing compound (I)”) and a compound having two nitrogen atoms (hereinafter, “nitrogen-containing compound”). (II) ”), a compound having three nitrogen atoms (hereinafter, also referred to as“ nitrogen-containing compound (III) ”), an amide group-containing compound, a urea compound, a nitrogen-containing heterocyclic compound and the like.

In the above formula (B), R ²⁰ , R ²¹ and R ²² are independently hydrogen atoms, optionally substituted linear, branched or cyclic alkyl groups, aryl groups or aralkyl groups, respectively. ..

Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline. Be done.

Examples of the nitrogen-containing compound (II) include ethylenediamine, N, N, N', N'-tetramethylethylenediamine and the like.

Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like. Be done.

Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea and the like.

Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholin and N- (undecylcarbonyloxyethyl) morpholin; pyrazine and pyrazole and the like.

[D] A nitrogen-containing compound having an acid dissociative group can also be used as the acid diffusion control agent. Examples of the nitrogen-containing compound having such an acid dissociative group include Nt-butoxycarbonylpiperidin, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, and Nt-butoxycarbonyl-2-. Phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) diphenylamine, Examples thereof include Nt-butoxycarbonyl-4-hydroxypiperidin and Nt-amyloxycarbonyl-4-hydroxypiperidin.

Further, as the [D] acid diffusion control agent, a photodisintegrating base that is exposed to exposure to generate a weak acid can also be used. Examples of the photodisintegrating base include onium salt compounds that are decomposed by exposure and lose their acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (5-1), an iodonium salt compound represented by the following formula (5-2), and the like.

In the above formulas (5-1) and (5-2), R ^{23 to} R ²⁷ are independently hydrogen atoms, alkyl groups, alkoxy groups, hydroxy groups or halogen atoms. E ^- and Q ^- are each ^{independently, OH -, R β -COO -} , R β -SO 3 - is an anion represented by or the following formula (5-3). However, R ^β is an alkyl group, an aryl group or an aralkyl group.

In the formula (5-3), R ²⁸ represents a linear or branched alkyl group having 1 to 12 carbon atoms, 1 the number of linear or branched fluorinated alkyl group or a C 1 to 12 carbon atoms ~ 12 linear or branched alkoxy groups. u is an integer from 0 to 2. When u is 2, the two R ^28s may be the same or different.

Examples of the photodisintegrating base include compounds represented by the following formulas.

Among these, as the photodisintegrating base, a sulfonium salt is preferable, a triarylsulfonium salt is more preferable, and triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are further preferable.

When the radiation-sensitive resin composition contains the [D] acid diffusion control agent, the lower limit of the content of the [D] acid diffusion control agent is 0.1 with respect to 100 parts by mass of the [A] polymer. It is preferably parts by mass, more preferably 0.3 parts by mass, and even more preferably 1 part by mass. The upper limit of the content is preferably 20 parts by mass, more preferably 15 parts by mass, and even more preferably 10 parts by mass. The radiation-sensitive resin composition may contain one or more [D] acid diffusion controllers.

<[E] Polymer>
The [E] polymer is a fluorine atom-containing polymer other than the [A] polymer. The radiation-sensitive resin composition can contain the [E] polymer as, for example, a water-repellent additive.

[E] As the lower limit of the fluorine atom content of the polymer, 1% by mass is preferable, 2% by mass is more preferable, 4% by mass is further preferable, and 7% by mass is particularly preferable. The upper limit of the fluorine atom content is preferably 60% by mass, more preferably 40% by mass, and even more preferably 30% by mass. The fluorine atom content (mass%) of the polymer can be calculated from the structure of the polymer obtained by ¹³ C-NMR spectrum measurement or the like.

Examples of the structural unit of the [E] polymer include the following structural unit (Ea) and the following structural unit (Eb). [E] The polymer may have one or more structural units (Ea) and structural units (Eb), respectively.

[Structural unit (Ea)]
The structural unit (Ea) is a structural unit represented by the following formula (6a). The fluorine atom content of the [E] polymer can be adjusted by having a structural unit (Ea).

In the above formula (6a), ^RD is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -CO-O-, -SO ₂ -O-NH-, -CO-NH- or -O-CO-NH-. R ^E is a monovalent fluorine-cycloaliphatic hydrocarbon group having a monovalent fluorinated chain hydrocarbon group or a 4 to 20 carbon atoms having 1 to 6 carbon atoms.

The monovalent fluorinated chain hydrocarbon group having 1 to 6 carbon atoms represented by R ^E, such as trifluoromethyl group, 2,2,2-trifluoroethyl group, perfluoroethyl group, 2,2 , 3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoron-propyl group, perfluoroi-propyl group, perfluoron-butyl group, Examples thereof include a perfluoroi-butyl group, a perfluorot-butyl group, a 2,2,3,3,4,5,5-octafluoropentyl group and a perfluorohexyl group.

The monovalent fluorine-cycloaliphatic hydrocarbon radical having 4 to 20 carbon atoms represented by R ^E, for example mono-fluoro cyclopentyl group, difluorocyclopentyl groups, perfluorocyclopentyl group, monofluoromethyl cyclohexyl group, difluorocyclohexyl group, Examples thereof include a perfluorocyclohexylmethyl group, a fluoronorbornyl group, a fluoroadamantyl group, a fluorobornyl group, a fluoroisobornyl group, a fluorotricyclodecyl group and a fluorotetracyclodecyl group.

Examples of the monomer giving the structural unit (Ea) include a linear partially fluorinated alkyl (meth) acrylic acid ester such as 2,2,2-trifluoroethyl (meth) acrylic acid ester;
Branched-chain partially fluorinated alkyl (meth) acrylic acid esters such as 1,1,1,3,3,3-hexafluoroi-propyl (meth) acrylic acid ester;
Linear perfluoroalkyl (meth) acrylic acid esters such as perfluoroethyl (meth) acrylic acid ester;
Branched chains such as perfluoroi-propyl (meth) acrylic acid esters (meth) acrylic acid esters having fluorinated chain hydrocarbon groups such as perfluoroalkyl (meth) acrylic acid esters,
(Meta) acrylic having a monocyclic fluorinated alicyclic saturated hydrocarbon group such as perfluorocyclopentyl methyl (meth) acrylic acid ester, monofluorocyclopentyl (meth) acrylic acid ester, perfluorocyclopentyl (meth) acrylic acid ester, etc. Acid ester;
Polycyclic fluorinated alicyclic saturated hydrocarbon groups such as fluoronorbornyl (meth) acrylic acid esters (meth) acrylic acid esters having fluorinated alicyclic hydrocarbon groups such as (meth) acrylic acid esters And so on. Among these, a (meth) acrylic acid ester having a fluorinated chain hydrocarbon group is preferable, a linear partially fluorinated alkyl (meth) acrylic acid ester is more preferable, and 2,2,2-trifluoroethyl (meth) is preferable. ) Acrylic ester is more preferred.

When the [E] polymer has a structural unit (Ea), the lower limit of the content ratio of the structural unit (Ea) is preferably 5 mol% with respect to all the structural units constituting the [E] polymer. More preferably mol%, even more preferably 20 mol%. The upper limit of the content ratio is preferably 95 mol%, more preferably 75 mol%, still more preferably 50 mol%. With such a content ratio, it is possible to develop a higher dynamic contact angle on the surface of the resist film during immersion exposure.

[Structural unit (Eb)]
The structural unit (Eb) is a structural unit represented by the following formula (6b). Since the [E] polymer has a structural unit (Eb), the hydrophobicity is increased, so that the dynamic contact angle of the surface of the resist film formed from the radiation-sensitive resin composition can be further improved.

In the above formula (6b), ^RF is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ²⁹ is a (s + 1) -valent hydrocarbon group having 1 to 20 carbon ^atoms, an oxygen atom at the terminal of ^{R 30} side of the ^{R 29,} a sulfur atom, -NR'-, carbonyl group, -CO-O-or The structure in which -CO-NH- is bound is also included. R'is a hydrogen atom or a monovalent organic group. R ³⁰ is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms or a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. X ² is a divalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms. A ¹ is an oxygen atom, -NR "-, -CO-O- * or -SO _2- O- *. R" is a hydrogen atom or a monovalent organic group. * Indicates a binding site that binds to R ³¹ . R ³¹ is a hydrogen atom or a monovalent organic group. s is an integer of 1-3. However, when s is 2 or 3, the plurality of R ³⁰ , X ² , A ¹ and R ³¹ may be the same or different, respectively.

When R ³¹ is a hydrogen atom, it is preferable in that the solubility of the [E] polymer in an alkaline developer can be improved.

Examples of the monovalent organic group represented by R ³¹ include a hydrocarbon group having 1 to 30 carbon atoms which may have an acid dissociative group, an alkali dissociative group or a substituent.

Examples of the structural unit (Eb) include structural units represented by the following formulas (6b-1) to (6b-3).

In the formula (6b-1) ~ (6b -3), R 29 ' is a divalent linear, branched or cyclic hydrocarbon group, saturated or unsaturated having 1 to 20 carbon atoms. R ^F , X ² , R ³¹ and s are synonymous with the above formula (6b). When s is 2 or 3, the plurality of X ² and R ³¹ may be the same or different, respectively.

When the [E] polymer has a structural unit (Eb), the lower limit of the content ratio of the structural unit (Eb) is preferably 5 mol% based on all the structural units constituting the [E] polymer. More preferably mol%, more preferably 15 mol%. The upper limit of the content ratio is preferably 90 mol%, more preferably 85 mol%, and even more preferably 80 mol%. By setting such a content ratio, the surface of the resist film formed from the radiation-sensitive resin composition can improve the degree of decrease in the dynamic contact angle in alkaline development.

[Structural unit (Ec)]
[E] The polymer may have a structural unit containing an acid dissociative group (hereinafter, also referred to as “structural unit (Ec)”) in addition to the structural units (Ea) and (Eb) (provided that the polymer has a structural unit (Ec)). , Excluding those corresponding to the structural unit (Eb)). [E] When the polymer has a structural unit (Ec), the shape of the obtained resist pattern becomes better. Examples of the structural unit (Ec) include the structural unit (II) in the above-mentioned [A] polymer.

When the [E] polymer has a structural unit (Ec), the lower limit of the content ratio of the structural unit (Ec) is preferably 5 mol% with respect to all the structural units constituting the [E] polymer, 25. More preferably mol%, even more preferably 50 mol%. The upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, still more preferably 70 mol%.

When the radiation-sensitive resin composition contains the [E] polymer, the lower limit of the content of the [E] polymer is preferably 0.1 part by mass with respect to 100 parts by mass of the base polymer. Parts by mass are more preferred, and parts by mass is even more preferred. The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass, and even more preferably 7 parts by mass.

The lower limit of the content of the [E] polymer is preferably 0.1 part by mass, more preferably 1 part by mass, and even more preferably 2 parts by mass with respect to 100 parts by mass of the [A1] polymer. The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass, and even more preferably 7 parts by mass. The radiation-sensitive resin composition may contain one or more [E] polymers.

<[F] polymer>
The [F] polymer is a polymer having a lower fluorine atom content than the [A] polymer and having a structural unit containing an acid dissociative group. The radiation-sensitive resin composition contains, for example, the [F] polymer as the base polymer when the [A] polymer is used as the water-repellent polymer additive ([A2] polymer). Is preferable. Examples of the structural unit containing an acid dissociative group include the structural unit (II) in the above-mentioned [A] polymer. The [F] polymer may have, for example, structural units (III) and (IV) in the [A] polymer and other structural units in addition to the structural unit (II) in the [A] polymer. ..

When the radiation-sensitive resin composition contains the [F] polymer, the lower limit of the content of the [F] polymer is 500 parts by mass with respect to 100 parts by mass of the [A2] polymer. Preferably, 700 parts by mass is more preferable, and 1,000 parts by mass is further preferable. The upper limit of the content is preferably 100,000, more preferably 20,000, and even more preferably 10,000 parts by mass.

The lower limit of the content of the [F] polymer is preferably 50 parts by mass, more preferably 80 parts by mass, and even more preferably 95 parts by mass with respect to 100 parts by mass of the base polymer. The upper limit of the content is, for example, 100 parts by mass. The radiation-sensitive resin composition may contain one or more [F] polymers.

<Other optional ingredients>
The radiation-sensitive resin composition may contain other optional components in addition to the above-mentioned [A] to [F] components. Examples of other optional components include an uneven distribution accelerator, a surfactant, an alicyclic skeleton-containing compound, a sensitizer, and the like. These other optional components may be used alone or in combination of two or more.

[Uneven distribution accelerator]
The uneven distribution accelerator resists the [A2] polymer and the [E] polymer more efficiently when the radiation-sensitive resin composition contains the [A2] polymer and the [E] polymer. It has the effect of segregating the film surface. By incorporating the uneven distribution accelerator in the radiation-sensitive resin composition, the amount of the [A2] polymer and the [E] polymer added can be reduced as compared with the conventional case. Therefore, it is possible to further suppress the elution of components from the resist film into the immersion liquid without impairing the LWR performance, etc., and to perform the immersion exposure at a higher speed by high-speed scanning, resulting in watermark defects. It is possible to improve the hydrophobicity of the surface of the resist film that suppresses defects derived from immersion such as. Examples of the compound that can be used as such an uneven distribution accelerator include low molecular weight compounds having a relative permittivity of 30 or more and 200 or less and a boiling point of 100 ° C. or more at 1 atm. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

Examples of the lactone compound include γ-butyrolactone, valero lactone, mevalonic lactone, norbornane lactone and the like. Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate and the like. Examples of the nitrile compound include succinonitrile. Examples of the polyhydric alcohol include glycerin and the like.

When the radiation-sensitive resin composition contains an uneven distribution accelerator, the lower limit of the content of the uneven distribution accelerator is based on 100 parts by mass of the total amount of the polymer contained in the radiation-sensitive resin composition. 10 parts by mass is preferable, 15 parts by mass is more preferable, 20 parts by mass is further preferable, and 25 parts by mass is particularly preferable. The upper limit of the content is preferably 500 parts by mass, more preferably 300 parts by mass, further preferably 200 parts by mass, and particularly preferably 100 parts by mass.

[Surfactant]
Surfactants have the effect of improving coatability, striation, developability and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol di. Nonionic surfactants such as stearate; commercially available products include KP341 (Shinetsu Chemical Industry Co., Ltd.), Polyflow No. 75, No. 95 (above, Kyoeisha Kagakusha), Ftop EF301, EF303, EF352 (above, Tochem Products), Megafuck F171, F173 (above, DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industry Co., Ltd.), etc. Can be mentioned. When the radiation-sensitive resin composition contains a surfactant, the upper limit of the content of the surfactant is 2 parts by mass with respect to 100 parts by mass of the total amount of the polymer contained in the radiation-sensitive resin composition. Part is preferable.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesiveness to a substrate, and the like. Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanane carboxylic acid, 2-adamantanone, and t-butyl 1-adamantane carboxylic acid;
Deoxycholic acid esters such as t-butyl deoxycholic acid, t-butoxycarbonylmethyl deoxycholic acid, and 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . ^17,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane and the like can be mentioned. When the radiation-sensitive resin composition contains an alicyclic skeleton-containing compound, the upper limit of the content of the alicyclic skeleton-containing compound is 100 parts by mass of the total amount of the polymer contained in the radiation-sensitive resin composition. On the other hand, 5 parts by mass is preferable.

[Sensitizer]
The sensitizer has an action of increasing the amount of acid produced from the [B] acid generator or the like, and has an effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition. Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyls, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. When the radiation-sensitive resin composition contains a sensitizer, the upper limit of the content of the sensitizer is 2% by mass with respect to 100 parts by mass of the total amount of the polymer contained in the radiation-sensitive resin composition. Part is preferable.

<Method for preparing radiation-sensitive resin composition>
In the radiation-sensitive resin composition, for example, an optional component such as [A] polymer, [B] acid generator, [C] solvent and, if necessary, [D] acid diffusion control agent, is mixed at a predetermined ratio. , Preferably, the obtained mixture can be prepared by filtering with, for example, a filter having a pore size of about 0.2 μm. The lower limit of the solid content concentration of the radiation-sensitive resin composition is preferably 0.1% by mass, more preferably 0.5% by mass, still more preferably 1% by mass. The upper limit of the solid content concentration is preferably 50% by mass, more preferably 30% by mass, still more preferably 10% by mass.

<Resist pattern formation method>
In the resist pattern forming method, a step of applying the radiation-sensitive resin composition to one surface of a substrate (hereinafter, also referred to as a “coating step”) and a resist film obtained by the coating step are exposed. A step of developing the exposed resist film (hereinafter, also referred to as “exposure step”) and a step of developing the exposed resist film (hereinafter, also referred to as “development step”) are provided.

According to the resist pattern forming method, since the radiation-sensitive resin composition is used, the LWR is small, the resolution is high, and the cross-sectional shape is high, while exhibiting excellent depth of focus, MEEF performance, and film shrinkage inhibitory property. It is possible to form a resist pattern having excellent rectangularity. Hereinafter, each step will be described.

[Coating process]
In this step, the radiation-sensitive resin composition is applied to one surface of the substrate. As a result, a resist film is formed. Examples of the substrate on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide, and wafers coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Application Laid-Open No. 6-12452 and JP-A-59-93448 may be formed on the substrate. Examples of the coating method include rotary coating (spin coating), cast coating, roll coating and the like. After coating, if necessary, prebaking (PB) may be performed to volatilize the solvent in the coating film. As the lower limit of the temperature of PB, 60 ° C. is preferable, and 80 ° C. is more preferable. The upper limit of the temperature is preferably 140 ° C., more preferably 120 ° C. As the lower limit of the PB time, 5 seconds is preferable, and 10 seconds is more preferable. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds. The lower limit of the average thickness of the resist film formed is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

In the case of immersion exposure, when the radiation-sensitive resin composition does not contain a water-repellent polymer additive, etc., the immersion liquid and the resist film are directly placed on the resist film formed above. An insoluble protective film for immersion may be provided in the immersion liquid for the purpose of avoiding contact. As the protective film for immersion, a solvent-removing protective film that is peeled off by a solvent before the developing process (see JP-A-2006-227632) and a developer-removing protective film that is peeled off at the same time as the development in the developing process (international publication (See 2005/069076 and 2006/035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer release type protective film for immersion.

[Exposure process]
In this step, the resist film obtained by the above coating step is exposed. This exposure is performed by irradiating the exposure light through a photomask (in some cases, through an immersion medium such as water). The exposure light includes electromagnetic waves such as visible light, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), X-rays, and γ-rays; charged particle beams such as electron beams and α-rays, depending on the line width of the target pattern. And so on. Among these, far ultraviolet rays, EUV and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV and electron beams are more preferable, and ArF excimer laser light, EUV and electron beams are more preferable. More preferred.

When the exposure is performed by immersion exposure, examples of the immersion liquid to be used include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient as small as possible so as to minimize distortion of the optical image projected on the film, but the exposure light is particularly ArF. In the case of the excimer laser light, in addition to the above viewpoints, it is preferable to use water from the viewpoints of easy availability and ease of handling. When water is used, an additive that reduces the surface tension of water and increases the surface activity may be added in a small proportion. It is preferable that this additive does not dissolve the resist film on the wafer and the influence on the optical coating on the lower surface of the lens can be ignored. Distilled water is preferable as the water to be used.

After the above exposure, post-exposure baking (PEB) is performed, and in the exposed portion of the resist film, the acid dissociative group contained in the [A] polymer or the like due to the acid generated from the [B] acid generator or the like by the exposure. It is preferable to promote dissociation. With this PEB, it is possible to increase the difference in solubility in the developing solution between the exposed portion and the unexposed portion. The lower limit of the temperature of PEB is preferably 50 ° C, more preferably 80 ° C. The upper limit of the temperature is preferably 180 ° C., more preferably 130 ° C. As the lower limit of the PEB time, 5 seconds is preferable, and 10 seconds is more preferable. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds.

According to the resist pattern forming method, since the above-mentioned radiation-sensitive resin composition is used, shrinkage of the resist film during PEB can be suppressed.

[Development process]
In this step, the exposed resist film is developed. As a result, a predetermined resist pattern can be formed. After development, it is generally washed with a rinse solution such as water or alcohol and dried. The developing method in the developing step may be alkaline development or organic solvent development. In the case of organic solvent development, since the exposed portion forms a resist pattern, there is a great advantage that the radiation-sensitive resin composition has excellent film shrinkage inhibitory properties.

In the case of alkaline development, the developing solution used for development includes, for example, 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 (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1 , 5-Diazabicyclo- [4.3.0] -5-Nonene and other alkaline compounds dissolved in at least one alkaline aqueous solution. Among these, the TMAH aqueous solution is preferable, and the 2.38 mass% TMAH aqueous solution is more preferable.

In the case of organic solvent development, examples of the developing solution include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents and alcohol solvents, and solvents containing the above organic solvents. Examples of the organic solvent include one or more of the solvents listed as the [C] solvent of the above-mentioned radiation-sensitive resin composition. Among these, ester-based solvents and ketone-based solvents are preferable. As the ester solvent, an acetic acid ester solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. The lower limit of the content of the organic solvent in the developing solution is preferably 80% by mass, more preferably 90% by mass, further preferably 95% by mass, and particularly preferably 99% by mass. Examples of the components other than the organic solvent in the developing solution include water, silicone oil and the like.

Examples of the developing method include a method of immersing the substrate in a tank filled with a developing solution for a certain period of time (dip method), and a method of developing by raising the developing solution on the surface of the substrate by surface tension and allowing it to stand still for a certain period of time (paddle method). ), A method of spraying the developer on the surface of the substrate (spray method), a method of continuing to apply the developer on the substrate rotating at a constant speed while scanning the developer application nozzle at a constant speed (dynamic discharge method). And so on.

<Polymer>
The polymer is a polymer having a structural unit containing the group (I). Since the polymer has the above-mentioned properties, it can be suitably used as a polymer component of the radiation-sensitive resin composition, and the radiation-sensitive resin composition containing the polymer has LWR performance, resolution, and so on. It is excellent in the rectangularness of the cross-sectional shape, the depth of focus, the MEEF performance, and the film shrinkage inhibitory property.

<Compound>
The compound is a compound represented by the above formula (i). Since the compound has the above-mentioned properties, it can be suitably used as a raw material monomer for the polymer.

The polymer and the compound are described in the above section [A] Polymer.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Each measurement in the example was carried out by the following method.

[Weight average molecular weight (Mw) and number average molecular weight (Mn)]
Using a Toso GPC column (2 "G2000HXL", 1 "G3000HXL", 1 "G4000HXL"), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0% by mass, sample Injection volume: 100 μL, column temperature: 40 ° C., detector: under the analytical conditions of a differential refractometer, measurement was performed by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[ ¹³ C-NMR analysis]
An analysis was performed to determine the content ratio (mol%) of structural units in each polymer using a nuclear magnetic resonance apparatus (“JNM-ECX400” manufactured by JEOL Ltd.) and deuterated chloroform as a measurement solvent.

<Compound synthesis>
[Example 1] (Synthesis of compound (M-1))
To a 300 mL round bottom flask, 10 g (65 mmol) of the compound represented by the following formula (a-1), 6.02 g (76 mmol) of pyridine and 40 mL of methylene chloride were added, and the mixture was stirred at 0 ° C. for 15 minutes under a nitrogen atmosphere. 9.94 g (70 mmol) of the compound represented by the following formula (m-1) was slowly added dropwise thereto. After completion of the dropping, the mixture was stirred at room temperature for 3 hours, and then 0.5 M aqueous hydrochloric acid solution was added for extraction. The obtained organic layer was washed twice with saturated aqueous sodium chloride solution and then dried over anhydrous sodium sulfate. After distilling off the solvent, the residue was purified by column chromatography to obtain 16.79 g of the compound represented by the following formula (m-1') (yield 99%). Next, 70 mL of N, N-dimethylformamide, 6.06 g (70.4 mmol) of methacrylic acid and 13.27 g (96 mmol) of potassium carbonate were added to a 300 mL round bottom flask, and the mixture was stirred at room temperature for 30 minutes. 16.79 g (64 mmol) of the compound (m-1') dissolved in 90 mL of N, N-dimethylformamide was added dropwise thereto over 5 minutes. Subsequently, 4.46 g (27 mmol) of potassium iodide was added, and the mixture was heated at 120 ° C. After adding ethyl acetate, it was washed twice with saturated aqueous sodium chloride solution. After distilling off the solvent, it was purified by column chromatography to obtain 14.20 g of the compound represented by the following formula (M-1) (yield 72%).

[Examples 2 to 12] (Synthesis of compounds (M-2) to (M-12))
By appropriately selecting a precursor and performing the same operation as in Example 1, compounds represented by the following formulas (M-2) to (M-12) were synthesized.

<Synthesis of polymer>
The monomers used in the synthesis of the [A1] polymer, the [A2] polymer, the [E] polymer and the [F] polymer are shown below.

[Synthesis of [A1] polymer and [F] polymer]
[Example 13] (Synthesis of polymer (A1-1))
2.00 g (50 mol%) of compound (M'-1), 8.15 g (40 mol%) of compound (M'-6) and 2.85 g (10 mol%) of compound (M-1) 2-butanone. A monomer solution was prepared by dissolving in 40 g and adding 0.75 g (5 mol% with respect to all the monomers) of azobisisobutyronitrile (AIBN) as a polymerization initiator. Next, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, heated to 80 ° C. with stirring, and the above-prepared monomer solution was added dropwise using a dropping funnel over 3 hours. .. The start of dropping was set as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was water-cooled and cooled to 30 ° C. or lower. A cooled polymerization reaction solution was put into 400 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 80 g of methanol, filtered again, and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A1-1) (15.8 g, yield 77). %). The Mw of the polymer (A1-1) was 7,200, and the Mw / Mn was 1.52. ¹³ As a result of C-NMR analysis, the content ratios of the structural units derived from (M'-1), (M'-6) and (M-1) were 50.3 mol% and 39.9 mol%, respectively. And 9.8 mol%.

[Example 38] (Synthesis of polymer (A1-26))
21.27 g (50 mol%) of compound (M'-14), 20.59 g (40 mol%) of compound (M'-1), 8.14 g (10 mol%) of compound (M-1), polymerization initiator After dissolving 2.15 g of AIBN (5 mol% with respect to all the compounds) and 0.56 g of t-dodecyl mercaptan in 50 g of propylene glycol monomethyl ether, the reaction temperature was maintained at 70 ° C. under a nitrogen atmosphere. , 16 hours copolymerization. After completion of the polymerization reaction, 500 g of the polymerization reaction solution was added dropwise to n-hexane to coagulate and purify the polymer. Next, 75 g of propylene glycol monomethyl ether was added to the polymer again, and then 75 g of methanol, 17 g of triethylamine and 3 g of water were further added, and the hydrolysis reaction was carried out for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, the obtained polymer was dissolved in 75 g of acetone, and then dropped into 1,000 g of water to coagulate, and the produced white powder was filtered and 17 at 50 ° C. The mixture was dried for a long time to obtain a white powdery polymer (A1-26) (33.8 g, yield 76%). The Mw of the polymer (A1-26) was 7,200, and the Mw / Mn was 1.70. ¹³ As a result of C-NMR analysis, the content ratio of each structural unit derived from p-hydroxystyrene, (M'-1) and (M-1) was 49.5 mol%, 40.3 mol% and 10 respectively. It was .2 mol%.

[Examples 14 to 37 and Synthesis Examples 1 to 3] (Synthesis of polymers (A1-2) to (A1-25) and (F-1) to (F-3))
The polymers (A1-2) to (A1-25) and (A1-25) and (A1-25) and (A1-25) and ( F-1) to (F-3) were synthesized.

[Synthesis of [E] polymer and [A2] polymer]
[Synthesis Example 4] (Synthesis of Polymer (E-1))
61.92 g (60 mol%) of compound (M'-2) and 38.08 g (40 mol%) of compound (M'-13) were dissolved in 100 g of 2-butanone, and dimethyl 2, as a polymerization initiator. A monomer solution was prepared by dissolving 6.52 g (5 mol% based on all monomers) of 2'-azobisisobutyrate. Next, a 1,000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, heated to 80 ° C. with stirring, and the monomer solution prepared above was added dropwise using a dropping funnel over 3 hours. .. The start of dropping was set as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization reaction solution was water-cooled and cooled to 30 ° C. or lower. After transferring the reaction solution to a 2 L separatory funnel, the polymerization reaction solution was uniformly diluted with 150 g of n-hexane, and 600 g of methanol was added and mixed. Then, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Then, the lower layer was recovered to obtain a propylene glycol monomethyl ether acetate solution of the polymer (E-1) (yield 60%). The Mw of the polymer (E-1) was 7,500, and the Mw / Mn was 2.12. ¹³ As a result of C-NMR analysis, the content ratios of each structural unit derived from (M'-2) and (M'-13) were 60.2 mol% and 39.8 mol%, respectively.

[Synthesis 5 and 39] (Synthesis of polymers (E-2) and (A2-1))
Polymers (E-2) and (A2-1) were synthesized by performing the same operation as in Synthesis Example 4 except that each monomer of the type and content shown in Table 3 below was used.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, [C] solvent, [D] acid diffusion control agent, and [G] uneven distribution accelerator used in the preparation of the radiation-sensitive resin composition are shown below.

[[B] Acid generator]
Each structural formula is shown below.
B-1: Triphenylsulfonium 2- (adamantane-1-ylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate B-2: Triphenylsulfonium norbornane sulton-2-yloxy Carbonyldifluoromethanesulfonate B-3: Triphenylsulfonium 3- (piperidin-1-ylsulfonyl) -1,1,2,2,3,3-hexafluoropropane-1-sulfonate B-4: Triphenylsulfonium adamantane- 1-Iloxycarbonyldifluoromethanesulfonate

[[C] Solvent]
C-1: Propylene glycol monomethyl ether acetate C-2: Cyclohexanone

[[D] Acid diffusion control agent]
Each structural formula is shown below.
D-1: Triphenylsulfonium salicylate D-2: Triphenylsulfonium 10-camphorsulfonate D-3: N- (n-undecane-1-ylcarbonyloxyethyl) morpholine D-4: 2,6-dii -Propylaniline D-5: Tris [2- (2-methoxymethoxy) ethyl] amine

[[G] Uneven distribution accelerator]
G-1: γ-Butyrolactone

[Preparation of radiation-sensitive resin composition for ArF exposure]
[Example 40]
[A1] 100 parts by mass of (A1-1) as a polymer, 8.5 parts by mass of (B-1) as an acid generator, and 2,240 parts by mass of (C-1) as a solvent. Parts and (C-2) 960 parts by mass, [D] 2.3 parts by mass as an acid diffusion control agent, [E] 3 parts by mass as a polymer, and [G] ] A radiation-sensitive resin composition (J-1) was prepared by blending 30 parts by mass of (G-1) as an uneven distribution accelerator and filtering with a polymer filter having a pore size of 0.2 μm.

[Examples 41 to 70 and Comparative Examples 1 to 3]
The radiation-sensitive resin compositions (J-2) to (J-31) and (J-2) and (J-31) are operated in the same manner as in Example 40 except that the components of the types and contents shown in Tables 4 and 5 below are used. CJ-1) to (CJ-3) were prepared.

[Examples 71 to 101 and Comparative Examples 4 to 6]
<Formation of resist pattern (1)> (Alkaline development)
A spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited) was used to apply the composition for forming an underlayer antireflection film ("ARC66" from Brewer Science) onto the surface of a 12-inch silicon wafer, and then the temperature was 205 ° C. A lower antireflection film having an average thickness of 105 nm was formed by heating for 60 seconds. A radiation-sensitive resin composition was applied onto the lower antireflection film using the spin coater, and PB was performed at 90 ° C. for 60 seconds. Then, it cooled at 23 degreeC for 30 seconds to form a resist film having an average thickness of 90 nm. Next, this resist film was subjected to an ArF excimer laser immersion exposure apparatus (NIKON's "NSR-S610C") under optical conditions of NA = 1.3 and dipole (Sigma 0.977 / 0.782). , 40 nm line and space (1L1S) mask pattern. After the exposure, PEB was performed at 90 ° C. for 60 seconds. Then, it was subjected to alkaline development using a 2.38 mass% TMAH aqueous solution as an alkaline developer, washed with water, and then dried to form a positive resist pattern. At the time of forming this resist pattern, the line width formed through a 1: 1 line-and-space mask having a target dimension of 40 nm is defined as the optimum exposure amount formed in a 1: 1 line-and-space line width of 40 nm. did.

<Formation of resist pattern (2)> (organic solvent development)
The negative type resist pattern was operated in the same manner as in the above resist pattern formation (1) except that the organic solvent was developed using n-butyl acetate instead of the TMAH aqueous solution and the resist was not washed with water. Was formed.

<Evaluation>
The radiation-sensitive resin composition was evaluated for the following items by measuring the formed resist pattern according to the following method. A scanning electron microscope (“CG-4100” manufactured by Hitachi High-Technologies Corporation) was used to measure the length of the resist pattern. The evaluation results are shown in Tables 6 and 7 below.

[LWR performance]
The resist pattern was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, and this value was defined as the LWR performance (nm). The smaller the LWR performance, the better. The LWR performance can be evaluated as "good" when it is 4.0 nm or less and "bad" when it exceeds 4.0 nm.

[Resolution]
When exposed through a mask pattern with a target dimension of 40 nm and a one-to-one line and space with an exposure amount equal to or less than the optimum exposure amount, the minimum line width of the line pattern obtained as the exposure amount decreases is resolved. It was set to (nm). The resolution can be evaluated as "good" when it is 34 nm or less, and as "poor" when it exceeds 34 nm.

[Rectangle of cross section]
The cross-sectional shape of the resist pattern resolved at the optimum exposure amount was observed, and the line width Lb in the middle in the height direction of the resist pattern and the line width La in the upper part of the film were measured. La / Lb was calculated from these measured values and used as an index of the rectangularness of the cross-sectional shape. The rectangularity of the cross-sectional shape is "good" when 0.94 ≤ La / Lb ≤ 1.06 and "poor" when La / Lb <0.94 or 1.06 <La / Lb. Can be evaluated.

[Depth of focus]
In the resist pattern resolved at the above optimum exposure amount, the dimensions when the focus is changed in the depth direction are observed, and the pattern dimensions fall within 90% to 110% of the standard without bridges or residues. The margin was measured, and the measurement result was taken as the depth of focus (nm). The depth of focus can be evaluated as "good" when it is 50 nm or more, and as "poor" when it is less than 50 nm.

[MEEF performance]
In the resist pattern resolved by irradiating the optimum exposure amount, the line width of the resist pattern formed by using the mask pattern having the line widths of 38 nm, 39 nm, 40 nm, 41 nm, and 42 nm is the vertical axis of the mask pattern. When the size of was plotted on the horizontal axis, the slope of the approximate straight line calculated by the least squares method was obtained, and this slope was used as the MEEF performance. The MEEF performance can be evaluated as "good" when it is 4.5 or less, and as "bad" when it exceeds 4.5.

[Membrane contraction inhibitory]
The film thickness of the resist film formed in the above "resist pattern formation (2)" was measured after performing full exposure at 70 mJ using an ArF excimer laser immersion exposure apparatus (NIKON's "NSR-S610C"). Then, the film thickness A was determined. Then, after performing PEB at 90 ° C. for 60 seconds, the film thickness was measured again to determine the film thickness B. 100 × (AB) / A (%) was calculated from the values of the film thickness A and the film thickness B, and the value of the film shrinkage rate by PEB was used as an index of the film shrinkage inhibitory property. The smaller the value, the better the membrane contraction inhibitory property. The membrane shrinkage inhibitory property can be evaluated as "good" when it is 15% or less, and as "poor" when it exceeds 15%.

[Preparation of radiation-sensitive resin composition for electron beam exposure]
[Example 102]
[A1] 100 parts by mass of (A1-1) as a polymer, 20 parts by mass of (B-1) as an acid generator, 4,280 parts by mass of (C-1) as a [C] solvent, and (C-2) 1,830 parts by mass and [D] 3.6 parts by mass of (D-1) as an acid diffusion control agent are mixed, and the obtained mixture is filtered through a polymer filter having a pore size of 0.2 μm. Prepared a radiation-sensitive resin composition (J-32).

[Example 103 and Comparative Examples 7 to 9]
The same procedure as in Example 102 was carried out except that the components of the types and contents shown in Table 8 below were used, and the radiation-sensitive resin compositions (J-33) and (CJ-4) to (CJ-6) were operated. Was prepared.

<Formation of resist pattern (3)> (Alkaline development)
A radiation-sensitive resin composition was applied to the surface of an 8-inch silicon wafer using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Limited), and PB was performed at 90 ° C. for 60 seconds. Then, it cooled at 23 degreeC for 30 seconds to form a resist film having an average thickness of 50 nm. Next, this resist film was irradiated with an electron beam using a simple electron beam drawing apparatus (“HL800D” manufactured by Hitachi, Ltd., output: 50 KeV, current density: 5.0 A / cm ² ). After irradiation, it was developed at 23 ° C. for 30 seconds using a 2.38 mass% TMAH aqueous solution as an alkaline developer, washed with water, and dried to form a positive resist pattern.

<Evaluation>
With respect to the formed resist pattern, the LWR performance, the resolvability, and the rectangularity of the cross-sectional shape were evaluated in the same manner as in the above-mentioned "Formation of resist pattern (2)". In the case of electron beam exposure, the LWR performance can be evaluated as "good" when it is 5.0 nm or less and "poor" when it exceeds 5.0. The evaluation results are shown in Table 9 below.

From the results of Tables 6, 7 and 9, according to the radiation-sensitive resin composition of the example, the LWR performance, the resolution, and the rectangularity of the cross-sectional shape are obtained in both ArF exposure and electron beam exposure. It can be seen that it is excellent in depth of focus, MEEF performance, and film shrinkage inhibitory property. In general, it is known that electron beam exposure shows the same tendency as EUV exposure. Therefore, according to the radiation-sensitive resin composition of Examples, even in EUV exposure, It is presumed to be excellent in LWR performance and the like.

According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, the LWR is small, the resolution is high, and the cross-sectional shape is rectangular while exhibiting excellent depth of focus, MEEF performance, and film shrinkage inhibitory property. An excellent resist pattern can be formed. The polymer of the present invention can be suitably used as a polymer component of the radiation-sensitive resin composition. The compound of the present invention can be suitably used as a monomer of the polymer. Therefore, these can be suitably used for semiconductor device manufacturing, which is expected to be further miniaturized in the future.

Claims (5)

The first polymer having the first structural unit represented by the following formula (1-1) and
Radiation-sensitive acid generator and
A radiation-sensitive resin composition containing a solvent.

(In the formula (1-1), Z is a group represented by the following formula (1).
In formula (1-1), R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L ² is a divalent organic group having 1 to 20 carbon atoms. )

(In the formula (1), R ¹ is a monovalent lactone ring group having 3 to 20 ring members. L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms, where R is. ^{When 1} is a monocyclic lactone ring group, L ¹ is a single bond. * Indicates a bond site with L ² in the above formula (1-1) .) The radiation-sensitive resin composition according to claim 1 , wherein the first polymer further has a second structural unit containing an acid dissociative group. The step of applying the radiation-sensitive resin composition according to claim 1 or 2 to one surface of the substrate, and
The step of exposing the resist film obtained by the above coating step and
A resist pattern forming method comprising the step of developing the exposed resist film. A polymer having a structural unit represented by the following formula (1-1).

(In the formula (1-1), Z is a group represented by the following formula (1).
In formula (1-1), R ² is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. L ² is a hydrocarbon group having 1 to 20 carbon atoms. )

(In the formula (1), R ¹ is a monovalent lactone ring group having 3 to 20 ring members. L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms, where R is. ^{When 1} is a monocyclic lactone ring group, L ¹ is a single bond. * Indicates a bond site with L ² in the above formula (1-1).) A compound represented by the following formula (i').

(In formula (i'), R ¹ is a monovalent lactone ring group having 3 to 20 carbon atoms. L ¹ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ² Is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. However, when R ¹ is a monocyclic lactone ring group, L ¹ is a single bond. L ⁴ has 1 to 20 carbon atoms. It is a hydrocarbon group .)