Chemically amplified negative resist composition and patterning method

Abstract

To provide a chemically amplified negative resist composition with high dissolution contrast and superior CDU and LWR performance, and a patterning method using the same.SOLUTION: A chemically amplified negative resist composition comprises (A) a polymer P comprising a repeating unit that generates acid upon exposure in a specified structure, a repeating unit that degrades under the action of acid to change developer solubility, and a repeating unit with a phenolic hydroxyl group and (B) a crosslinker X, which is a melamine compound, a glycoluril compound, a urea compound or an epoxy compound, substituted with at least one group selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a chemically amplified negative resist composition and a pattern forming method. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming finer at a rapid pace. This is because 5G high-speed communications and artificial intelligence (AI) are becoming more widespread, and high-performance devices are needed to process these. The most advanced miniaturization technology is extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, which is used to mass-produce 5 nm node devices. Furthermore, studies are also underway to use EUV lithography for next-generation 3 nm node devices and the generation after that, 2 nm node devices.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem. In order to ensure resolution in fine patterns with processing dimensions of 45 nm or less, it has been proposed that control of acid diffusion is important in addition to improving the dissolution contrast, as has been proposed in the past (Non-Patent Document 1). However, since chemically amplified resist compositions increase sensitivity and contrast by acid diffusion, if one tries to suppress acid diffusion to the maximum extent by lowering the post-exposure bake (PEB) temperature or shortening the time, the sensitivity and contrast will decrease significantly.

[0004] When forming a pattern with a pitch narrower than the wavelength, it is effective to use interference exposure. In particular, high-contrast light interference between lines in the X direction and lines in the Y direction generates high-contrast black spots. By combining this with a negative resist composition, a hole pattern with excellent dimensional uniformity (CDU) can be formed (Non-Patent Document 2). In Non-Patent Document 2, a negative resist composition using a crosslinking agent that reacts between polymers with acid is used. Such chemically amplified negative resist compositions have problems such as pattern collapse caused by the image blurring problem due to acid diffusion described above, and deterioration of CDU and edge roughness (LWR).

[0005] Here, the creation of negative patterns by organic solvent development is a method that has been used for a long time. Cyclized rubber-based resist compositions use xylene or the like as a developer, and early chemically amplified resist compositions based on poly-tert-butoxycarbonyloxystyrene used anisole as a developer to obtain negative patterns (Non-Patent Document 3).

[0006] A negative pattern can be formed by exposure to ArF excimer laser light and organic solvent development using a chemically amplified resist composition based on a polymethacrylate polymer in which the carboxyl group is substituted with an acid labile group (Patent Document 1). This organic solvent development process is used in combination with immersion exposure and double patterning using an optical system with an NA exceeding 1 for device manufacturing at the 20 nm node and beyond.

[0007] In recent years, with the advancement of photomask technology, bright masks for EUV lithography have been developed, and the demand for negative resist compositions that are optically advantageous for forming hole patterns is increasing.

[0008] Negative patterns are also advantageous when forming isolated patterns or pillar patterns using EUV lithography. In this case, the mask has a higher proportion of light-shielding areas, which has the advantage of being less susceptible to defects in the mask blanks.

[0009] Organic solvent development causes less swelling than alkaline aqueous solution development, which can lead to superior CDU and LWR. However, it has a problem of low resolution due to a lower dissolution contrast compared to alkaline aqueous solution development. It is necessary to develop a resist that has improved dissolution contrast while maintaining resolution even in organic solvent development.

[0010] Incidentally, in order to suppress the above-mentioned acid diffusion, a positive resist composition for alkaline aqueous solution development containing a polymer containing a repeating unit derived from an onium salt of a sulfonic acid having a polymerizable unsaturated bond has been proposed (Patent Document 1). Such so-called polymer-bound acid generators are characterized by a very short acid diffusion because polymer-type sulfonic acid is generated by exposure. In addition, sensitivity can be improved by increasing the ratio of the acid generator. In the case of an acid generator, which is an additive, increasing the amount of the additive increases the sensitivity, but in this case, the acid diffusion distance also increases proportionally. Since acid diffuses non-uniformly, increasing acid diffusion deteriorates LWR and CDU. It can be said that polymer-bound acid generators have high capabilities in terms of the balance between sensitivity, LWR, and CDU.

[0011] However, since the above-mentioned polymer-bonded acid generator is a polymer, its solubility in the developer for organic solvent development is extremely low, and it has been considered difficult to use it in a negative resist composition for organic solvent development. In order to introduce it into a negative resist composition for organic solvent development, it was necessary to develop a polymer-bonded acid generator that exhibits sufficient solubility in the organic solvent used for development. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent No. 4425776 [Non-patent literature]

[0013] [Non-Patent Document 1] Proc. SPIE Vol. 5377, p.255 (2004) [Non-Patent Document 2] IEEE IEDM Tech. Digest 61 (1996) [Non-Patent Document 3] Proc. SPIE Vol. 7274, p.72740N (2009) Summary of the Invention [Problem to be solved by the invention]

[0014] There is a need for a negative resist composition for organic solvent development that exhibits high dissolution contrast and high resolution, and has good CDU and LWR performance. There is also a need for a negative resist composition for organic solvent development that employs a polymer-bound acid generator that exhibits higher solubility in organic solvents than ordinary acid generators.

[0015] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a chemically amplified negative resist composition having high dissolution contrast and excellent CDU and LWR performance, and a pattern forming method using the same. [Means for solving the problem]

[0016] As a result of intensive research into achieving the above-mentioned object, the inventors have found that by using a polymer containing a repeating unit having an acid labile group in a side chain that aids solubility, as a polymer-bonded acid generator, and a crosslinker, it is possible to obtain a chemically amplified negative resist composition that has high contrast and excellent resolution, does not leave residue in unexposed areas, has improved LWR and CDU performance, and has excellent resolution, and have completed the present invention.

[0017] That is, the present invention provides the following chemically amplified negative resist composition and pattern forming method. 1. (A) a polymer P including a repeating unit represented by any one of the following formulas (A1) to (A4) that generates an acid upon exposure, a repeating unit represented by formula (B) that decomposes under the action of an acid to change the solubility in a developer, and a repeating unit having a phenolic hydroxy group represented by the following formula (C); (B) a crosslinking agent X which is a melamine compound, a glycoluril compound, a urea compound or an epoxy compound substituted with at least one group selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group; A chemically amplified negative resist composition comprising: [ka] (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond or a phenylene group. X 2 is *-C(=O)-OX 21 -, *-C(=O)-NH-X 21 -or*-OX 21 - X 21 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. X 3 each independently represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 31 - X 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond and a lactone ring. X 4 each independently represents a single bond or *-X 41 -C(=O)-O-. X 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. X 5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-C(=O)-OX 51 -, *-C(=O)-N(H)-X 51 -or*-OX 51 - X 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * indicates a bond to a carbon atom in the main chain. R 1 and R 2 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 and may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. a is an integer from 0 to 3. [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OY 11 -It is. Y 11represents an aliphatic hydrocarbylene group having 1 to 20 carbon atoms, a phenylene group, or a naphthylene group, and the hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom of the main chain. R B and R C are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, R B and R C may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 11 is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 5 carbon atoms, or a fluorinated saturated hydrocarbyloxy group having 1 to 5 carbon atoms. R 12 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. b1 is an integer from 0 to 2. b2 is an integer from 0 to 5. b3 is an integer from 0 to 2. [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 21 represents a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. c1 is an integer from 1 to 4. c2 is an integer from 0 to 4, provided that 1≦c1+c2≦5. 2. The chemically amplified negative resist composition of 1, wherein b1 is 1 or 2. 3. The chemically amplified negative resist composition of 1 or 2, wherein the polymer P further comprises a repeating unit containing a lactone ring. 4. The resist composition according to any one of 1 to 3, further comprising an onium salt quencher represented by the following formula (Q1) or (Q2): [ka] (In the formula, R 31 represents a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, except for those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. R 32 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. Mq + is an onium cation. 5. Any one of the chemically amplified negative resist compositions according to 1 to 4, further comprising an organic solvent. 6. Any one of the chemically amplified negative resist compositions according to 1 to 5, further comprising a surfactant. 7. A pattern forming method comprising the steps of forming a resist film on a substrate using the chemically amplified negative resist composition according to any one of 1 to 6, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer containing an organic solvent. 8. The pattern formation method according to 7, further comprising a step of heating the resist film after exposure and before development. Effect of the Invention

[0018] The polymer-bound acid generator containing a repeating unit having an acid labile group represented by formula (B) exhibits high solvent solubility and does not leave any residue after development in unexposed areas. In addition, due to its low acid diffusibility, it has high dissolution contrast, LWR and CDU performance. In addition, by including a crosslinking agent in the composition, the polymer chains are crosslinked by the acid generated from the acid generator in the exposed areas, resulting in high molecular weight in the exposed areas, and further resulting in an acid generator with a short acid diffusion length. In addition, since the difference in dissolution rate between the unexposed and exposed areas becomes large, a high dissolution contrast can be obtained, and a pattern with high rectangularity, small LWR and improved CDU can be obtained. [Brief description of the drawings]

[0019] [Figure 1] 1 shows contrast curves of the resist films of Example 3-17 and Comparative Example 3-7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [Chemically amplified resist composition] The chemically amplified resist composition of the present invention contains (A) a polymer P that includes a repeating unit that generates acid upon exposure, a repeating unit that decomposes under the action of acid to change its solubility in a developer, and a repeating unit that has a phenolic hydroxy group, and (B) a crosslinking agent X that is a melamine compound, a glycoluril compound, a urea compound, or an epoxy compound substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group.

[0021] [(A) Polymer P] Polymer P, component (A), functions as a base polymer. The repeating unit contained in polymer P that generates an acid upon exposure to light is a repeating unit represented by the following formula (A1) (hereinafter also referred to as repeating unit A1), a repeating unit represented by the following formula (A2) (hereinafter also referred to as repeating unit A2), a repeating unit represented by the following formula (A3) (hereinafter also referred to as repeating unit A3), or a repeating unit represented by the following formula (A4) (hereinafter also referred to as repeating unit A4). [ka]

[0022] In formulas (A1) to (A4), R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond or a phenylene group. 2 is *-C(=O)-OX 21 -, *-C(=O)-NH-X 21 -or*-OX 21 - X 21 X is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 each independently represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 31 - X 31 X is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. 4 each independently represents a single bond or *-X 41 -C(=O)-O-. X 41 X is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-C(=O)-OX 51 -, *-C(=O)-N(H)-X 51 -or*-OX 51 - X 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. * represents a bond to a carbon atom in the main chain.

[0023] X 21 , X 31 and X 51 The aliphatic hydrocarbylene group represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,3-diyl group, a butane-1,4-diyl group, a 1,1-dimethylethane-1,2-diyl group, a pentane-1,5-diyl group, a 2-methylbutane-1,2 alkanediyl groups having 1 to 20 carbon atoms, such as a-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, and decane-1,10-diyl group; cycloalkanediyl groups having 3 to 20 carbon atoms, such as a cyclopropanediyl group, cyclobutane-1,1-diyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; polycyclic saturated hydrocarbylene groups having 4 to 20 carbon atoms, such as an adamantanediyl group and a norbornanediyl group; and divalent groups obtained by combining these.

[0024] X 41 The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include, but are not limited to, those shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0025] In formula (A1), R 1 and R 2are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these, with an aryl group being preferred. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2 A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0026] Also, R 1 and R 2 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. Specific examples include those represented by the following formula. In the following formula, the dashed line represents X 2 Represents a bond with . [ka]

[0027] Specific examples of the cation of the repeating unit A1 include, but are not limited to, those shown below. A is the same as above. [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] In formula (A1), M -is a non-nucleophilic counter ion. Specific examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion; fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion, and nonafluorobutanesulfonate ion; arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion, and 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as mesylate ion and butanesulfonate ion; imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, and bis(perfluorobutylsulfonyl)imide ion; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

[0035] Further, examples of the non-nucleophilic counter ion include a sulfonate anion represented by the following formula (A1-1) in which the α-position is substituted with a fluorine atom, and a sulfonate anion represented by the following formula (A1-2) in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group. [ka]

[0036] In formula (A1-1), R 3is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, a hydrocarbylcarbonyloxy group having 2 to 30 carbon atoms, or a hydrocarbyloxycarbonyl group having 2 to 30 carbon atoms, and may contain a halogen atom, an ether bond, an ester bond, a carbonyl group, or a lactone ring. The hydrocarbyl group and the hydrocarbyl moiety of the hydrocarbylcarbonyloxy group and hydrocarbyloxycarbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, a cyclohexyl group, a cyclopentyl group, a cyclohex ... Examples of the aryl group include cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms, such as an allyl group, a norbornylmethyl group, a tricyclodecyl group, a tetracyclododecyl group, a tetracyclododecylmethyl group, and a dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 30 carbon atoms, such as an allyl group and a 3-cyclohexenyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; aralkyl groups having 7 to 30 carbon atoms, such as a benzyl group and a diphenylmethyl group; and groups obtained by combining these. 3 In addition, a part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a hetero atom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and the -CH 2A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, and a 3-oxocyclohexyl group.

[0037] In formula (A1-2), R 4 R is a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbylcarbonyl group having 2 to 30 carbon atoms, and may contain a halogen atom, an ether bond, an ester bond, a carbonyl group, or a lactone ring. 5 is a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. The hydrocarbyl group and the hydrocarbyl carbonyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 3 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. 5 As the alkyl group, a trifluoromethyl group is preferable.

[0038] Specific examples of the sulfonate anion represented by formula (A1-1) or (A1-2) include, but are not limited to, those shown below. In the following formula, R 5 is the same as above, and Ac is an acetyl group. [ka]

[0039]

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[0040]

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[0041]

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[0042]

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[0043]

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[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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[0049] In formula (A2) and (A3), L 1is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Among these, from the viewpoint of synthesis, an ether bond, an ester bond or a carbonyl group is preferred, and an ester bond or a carbonyl group is more preferred.

[0050] In formula (A2), Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 1 and Rf 2 In order to increase the acid strength of the generated acid, each of Rf is preferably a fluorine atom. 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Of these, Rf 3 and Rf 4 At least one of these is preferably a trifluoromethyl group.

[0051] In formula (A3), Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 Of these, Rf 5 and Rf 6 At least one of these is preferably a trifluoromethyl group.

[0052] In the formulae (A2) and (A3), a is an integer of 0 to 3, with 1 being preferred.

[0053] Specific examples of the anion of the repeating unit A2 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] Specific examples of the anion of the repeating unit A3 include, but are not limited to, those shown below. A is the same as above. [ka]

[0060] [ka]

[0061] [ka]

[0062] Specific examples of the anion of the repeating unit A4 include, but are not limited to, those shown below. A is the same as above. [ka]

[0063] In formulas (A2) to (A4), A + is an onium cation. Examples of the onium cation include a sulfonium cation, an iodonium cation, and an ammonium cation. The onium cation is preferably a sulfonium cation or an iodonium cation, and more preferably a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka]

[0064] In formulas (cation-1) and (cation-2), R ct1 ~R ct5 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these, with an aryl group being preferred. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0065] Also, R ct1 and R ct2 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, specific examples of the ring include those represented by the following formulas: [ka] (In the formula, the dashed line represents R ct3 )

[0066] Specific examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071]

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[0072]

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[0073]

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[0074]

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[0075]

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[0076]

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[0077]

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[0078]

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[0079]

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[0080]

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[0081]

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[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085] [ka]

[0086] [ka]

[0087] Specific examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [ka]

[0088] Specific examples of the repeating units A1 to A4 include any combination of the above-mentioned anions and cations.

[0089] As the repeating unit that generates an acid upon exposure, the repeating units A2, A3 and A4 are preferred from the viewpoint of controlling acid diffusion, the repeating units A2 and A4 are more preferred from the viewpoint of the acid strength of the generated acid, and the repeating unit A2 is even more preferred from the viewpoint of solvent solubility.

[0090] The repeating unit having an acid labile group containing a fluorine atom-containing aromatic ring, which is contained in the polymer P (hereinafter also referred to as repeating unit B), is represented by the following formula (B). [ka]

[0091] In formula (B), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0092] In formula (B), Y 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OY 11 -It is. Y 11 represents an aliphatic hydrocarbylene group having 1 to 20 carbon atoms, a phenylene group, or a naphthylene group, and the hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom of the main chain.

[0093] Y 1 The aliphatic hydrocarbylene group represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,3-diyl group, a butane-1,4-diyl group, a 1,1-dimethylethane-1,2-diyl group, a pentane-1,5-diyl group, a 2-methylbutane-1,2 alkanediyl groups having 1 to 20 carbon atoms, such as a-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, and decane-1,10-diyl group; cycloalkanediyl groups having 3 to 20 carbon atoms, such as a cyclopropanediyl group, cyclobutane-1,1-diyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; polycyclic saturated hydrocarbylene groups having 4 to 20 carbon atoms, such as an adamantanediyl group and a norbornanediyl group; and divalent groups obtained by combining these.

[0094] Y in formula (B1) 1 Specific examples of structures in which R is changed include, but are not limited to, those shown below. A is the same as above, and the dashed line represents R in formula (B). B and R C represents the bond to the carbon atom to which it is bonded. [ka]

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] In formula (B), R B and R C are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, 2-ethylhexyl, and n-octyl; and cyclic saturated hydrocarbyl groups such as cyclopentyl, cyclohexyl, norbornyl, tricyclodecyl, and adamantyl.

[0099] Also, R B and R Cand may be bonded to each other to form a ring together with the carbon atom to which they are bonded. Examples of the ring include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, etc. Of these, a cyclopentane ring and a cyclohexane ring are preferred.

[0100] In formula (B), R 11 is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 5 carbon atoms, or a fluorinated saturated hydrocarbyloxy group having 1 to 5 carbon atoms. Examples of the fluorinated saturated hydrocarbyl group include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoro-2-propyl group, and a nonafluorobutyl group. Examples of the fluorinated saturated hydrocarbyloxy group include a fluoromethoxy group, a difluoromethoxy group, a trifluoromethoxy group, a 2,2,2-trifluoroethoxy group, a pentafluoroethoxy group, a pentafluoropropoxy group, a 1,1,1,3,3,3-hexafluoro-2-propoxy group, and a nonafluorobutoxy group. Among these, R 11 is preferably a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 5 carbon atoms, and more preferably a fluorine atom or a trifluoromethyl group.

[0101] In formula (B), R 12 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R B and R C Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0102] In formula (B), b1 is an integer of 0 to 2. b2 is an integer of 0 to 5, preferably 0 or 1. b3 is an integer of 0 to 2. When b3 is 0, it is a benzene ring, when b3 is 1, it is a naphthalene ring, and when b3 is 2, it is an anthracene ring, but from the viewpoint of solvent solubility, it is preferable that b3 is 0 and is a benzene ring.

[0103] The repeating unit B is preferably one represented by the following formula (B1). [ka] (In the formula, R A , Y 1 , R B , R C , R 11 , R 12 , b1 and b2 are the same as above.)

[0104] The monomer MB which gives the repeating unit B can be produced, for example, according to the following scheme, but is not limited thereto. [ka] (In the formula, R A , Y 1 , R B , R C , R 11 , R 12 , b1, b2 and b3 are the same as above. Hal is a halogen atom other than a fluorine atom.

[0105] The first step is a step of reacting a ketone compound SM-2, which is commercially available or can be synthesized by a known synthesis method, with a Grignard reagent or an organolithium reagent prepared from a halide SM-1 to obtain a monomer precursor Pre-MB.

[0106] The reaction can be carried out by a known organic synthesis method. Specifically, metallic magnesium or metallic lithium is suspended in an ether solvent such as tetrahydrofuran (THF) or diethyl ether, and the halide SM-1 diluted with the solvent used is added dropwise to prepare a Grignard reagent or an organolithium reagent. When preparing a Grignard reagent, particularly when the halide SM-1 is a chloride, the reaction can be efficiently started by adding a small amount of 1,2-dibromoethane or iodine before starting the dropwise addition of the halide SM-1. A ketone compound SM-2 diluted with the solvent used is added dropwise to the prepared Grignard reagent or organolithium reagent. The reaction temperature is from room temperature to the boiling point of the solvent used. The reaction time is usually about 30 minutes to 2 hours, although it is desirable to follow the reaction by gas chromatography (GC) or silica gel thin layer chromatography (TLC) to complete the reaction in terms of yield. The monomer precursor Pre-B1 can be obtained from the reaction mixture by a normal aqueous work-up. The resulting monomer precursor Pre-B1 can be purified, if necessary, by a conventional method such as distillation, chromatography, or recrystallization.

[0107] The second step is a step of obtaining a monomer MB by introducing a polymerizable group via an ester bond into Pre-MB, which is the tertiary alcohol obtained in the first step.

[0108] The reaction can be carried out by a known organic synthesis method. Specifically, the tertiary alcohol of Pre-B1 is dissolved in a solvent such as toluene, hexane, THF, or acetonitrile in the presence of an organic base such as triethylamine or pyridine, and an acid halide such as methacrylic acid chloride or acrylic acid chloride is added dropwise to carry out the reaction. 4-Dimethylaminopyridine may be added to accelerate the reaction rate. The reaction temperature is from 5°C to the boiling point of the solvent used. The reaction time is usually about 1 to 24 hours, although it is desirable to follow the reaction by GC or TLC and complete the reaction in terms of yield. Monomer MB can be obtained from the reaction mixture by a normal aqueous work-up. The obtained monomer MB can be purified according to a normal method such as distillation, chromatography, or recrystallization, if necessary.

[0109] Specific examples of the repeating unit B include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0110] [ka]

[0111] [ka]

[0112] [ka]

[0113] [ka]

[0114] [ka]

[0115]

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[0116]

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[0117]

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[0118]

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[0119]

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[0120]

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[0121]

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[0122]

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[0123]

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[0124]

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[0125]

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[0126]

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[0127]

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[0128]

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[0129]

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[0130]

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[0131]

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[0132]

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[0133]

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[0134]

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[0135]

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[0136] [ka]

[0137] [ka]

[0138] [ka]

[0139] [ka]

[0140] [ka]

[0141] The acid labile group in which a carboxylic acid is protected by a tertiary alcohol having an aryl group has a very low activation energy for the deprotection reaction by an acid catalyst compared to the acid labile group of a tertiary alkyl group such as a tert-butyl group, and the deprotection reaction proceeds even at a temperature of about 50°C. If a polymer having an acid labile group with a low activation energy for the deprotection reaction is used as the base polymer, the PEB temperature becomes too low, making it difficult to control the temperature uniformity or to control the diffusion of the acid. If the acid diffusion distance cannot be controlled, the CDU and limit resolution of the developed pattern will decrease. A moderate PEB temperature is required for acid diffusion control, and a temperature in the range of about 80 to 100°C is appropriate.

[0142] Another problem with using low activation energy protecting groups is that in the case of polymers in which a photoacid generator is copolymerized, the protecting group is removed during polymerization. Photoacid generators of onium salts are basically neutral, but heating during polymerization can cause partial dissociation of the onium salt, and when a repeating unit having a phenolic hydroxyl group is also copolymerized at the same time, an exchange reaction between the proton of the phenolic hydroxyl group and the cation of the photoacid generator can occur, generating acid and causing deprotection of the protecting group. Deprotection during polymerization is particularly noticeable when low activation energy protecting groups are used.

[0143] As mentioned above, acid labile groups in which carboxylic acids are protected by tertiary alcohols having aryl groups have the advantage of being highly resistant to etching because they have a benzene ring, but when a photoacid generator is copolymerized, elimination occurs during polymerization. Adding an electron-withdrawing group to the benzene ring increases the activation energy of deprotection. This is thought to be because the electron-withdrawing group reduces the stability of the benzyl cation, which is an intermediate in deprotection. By adding an electron-withdrawing group to a protecting group that is very easy to deprotect, the reactivity of the deprotection reaction can be reduced and optimized.

[0144] Fluorine atoms have a high absorption rate for EUV with a wavelength of 13.5 nm, which is said to have a sensitizing effect that improves sensitivity. Introducing fluorine atoms into a protecting group is expected to improve sensitivity. However, when fluorine atoms are introduced into an acid labile group of a tertiary alkyl group, the stability of the intermediate cation in the deprotection reaction becomes very low due to the electron-withdrawing effect of fluorine, so that no olefin is produced and the deprotection reaction does not occur. However, tertiary acid labile groups with aromatic groups containing fluorine atoms have optimal stability of the intermediate cation and show moderate deprotection reactivity.

[0145] As described above, in order to suppress acid diffusion and improve dissolution contrast and etching resistance, the repeating unit B is used as a repeating unit of the base polymer of a chemically amplified negative resist composition, which results in a significantly higher dissolution rate contrast in an organic solvent developer before and after exposure, a high suppression effect of acid diffusion, high resolution, good pattern shape and LWR after exposure, and excellent etching resistance.

[0146] The repeating unit having a phenolic hydroxy group contained in the polymer P (hereinafter also referred to as repeating unit C) is represented by the following formula (C). [ka]

[0147] In formula (C), R A Y is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 21 is a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. c1 is an integer of 1 to 4. c2 is an integer of 0 to 4, with the proviso that 1≦c1+c2≦5.

[0148] R 21 The hydrocarbyl group represented by the formula (A1) and the hydrocarbyl moiety of the hydrocarbyloxy group, the hydrocarbylcarbonyl group, the hydrocarbylcarbonyloxy group and the hydrocarbyloxycarbonyl group may be saturated or unsaturated and may be linear, branched or cyclic. 1 and R 2Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0149] Examples of the repeating unit C include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0150] [ka]

[0151] [ka]

[0152] Polymer P may further contain at least one repeating unit selected from the repeating units represented by the following formulas (a1) (hereinafter also referred to as repeating unit a1) and (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0153] In formulas (a1) and (a2), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 11 -It is. 11 Z is a saturated hydrocarbylene group having 1 to 20 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond and a lactone ring. 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 22 X is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom.A and X B each independently represents an acid labile group not containing an aromatic ring, and d represents an integer of 0 to 4.

[0154] In formulas (a1) and (a2), X A and X B Examples of the acid labile group represented by the formula (I) include those described in JP-A-2013-80033 and JP-A-2013-83821.

[0155] Typically, the acid labile group includes those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0156] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a saturated hydrocarbyl group having 1 to 40 carbon atoms, and may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The saturated hydrocarbyl group may be linear, branched, or cyclic. The saturated hydrocarbyl group preferably has 1 to 20 carbon atoms.

[0157] In formula (AL-1), e is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0158] In formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms, and may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be linear, branched, or cyclic. L2 , R L3 and R L4Any two of these may be bonded to each other to form a ring having 3 to 20 carbon atoms together with the carbon atom or the carbon atom and oxygen atom to which they are bonded. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0159] In formula (AL-3), R L5 , R L6 and R L7 are each independently a saturated hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The saturated hydrocarbyl group may be linear, branched, or cyclic. L5 , R L6 and R L7 Any two of these may be bonded to each other to form, together with the carbon atom to which they are bonded, a ring having 3 to 20 carbon atoms. As the ring, a ring having 4 to 16 carbon atoms is preferable, and an alicyclic ring is particularly preferable.

[0160] Specific examples of the repeating unit a1 include, but are not limited to, those shown below. A and X A is the same as above. [ka]

[0161] [ka]

[0162] [ka]

[0163] Specific examples of the repeating unit a2 include, but are not limited to, those shown below. A and X B is the same as above. [ka]

[0164] The polymer P may further contain a repeating unit represented by the following formula (D) (hereinafter also referred to as repeating unit D). [ka]

[0165] In formula (D1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 3 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 31 -It is. 31 represents a saturated hydrocarbylene group having 1 to 20 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom of the main chain. Y A is a hydrogen atom or a group having 1 to 20 carbon atoms containing at least one selected from a hydroxy group, a cyano group, a carbonyl group, a carboxy group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, and a carboxylic anhydride (-C(=O)-OC(=O)-).

[0166] Examples of the repeating unit D include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0167] [ka]

[0168] [ka]

[0169]

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[0170]

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[0171]

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[0172]

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[0173]

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[0174]

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[0175]

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[0176]

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[0177]

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[0178]

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[0179]

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[0180] [ka]

[0181] [ka]

[0182] The polymer P may further include a repeat unit E derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or a derivative thereof. Monomers providing the repeat unit E include, but are not limited to, those shown below. [ka]

[0183] The polymer P may further comprise repeat units F derived from indane, vinylpyridine or vinylcarbazole.

[0184] In polymer P, the content ratios of repeating units A1, A2, A3, A4, a1, a2, B, C, D, E, and F are preferably 0 ≦ A1 < 1.0, 0 ≦ A2 < 1.0, 0 ≦ A3 < 1.0, 0 ≦ A4 < 1.0, 0 < A1 + A2 + A3 + A4 < 1.0, 0 ≦ a1 ≦ 0.8, 0 ≦ a2 ≦ 0.8, 0 < B < 1.0, 0 < C < 1.0, 0 ≦ D ≦ 0.8, 0 ≦ E ≦ 0.8, and 0 ≦ F ≦ 0.4, more preferably 0.05 ≦ A1 ≦ 0.9, 0.05 ≦ A2 ≦ 0.9, 0.05 ≦ A3 ≦ 0.9, 0.05 ≦ A4 ≦ 0.9, 0.05 ≦ A1 + A2 + A3 + A4 ≦ 0.9, 0 ≦ a1 ≦ 0.7, 0 ≦ a2 ≦ 0.7, 0 ≦ a1 + a2 ≦ 0.7, 0.09 ≦ B ≦ 0.7, 0.01 ≦ C ≦ 0.4, 0 ≦ D ≦ 0.7, 0 ≦ E ≦ 0.7, and 0 ≦ F ≦ 0.3, and even more preferably 0.1 ≦ A1 ≦ 0.8, 0.1 ≦ A2 ≦ 0.8, 0.1 ≦ A3 ≦ 0.8, 0.1 ≦ A4 ≦ 0.8, 0.1 ≦ A1 + A2 + A3 + A4 ≦ 0.8, 0 ≦ a1 ≦ 0.6, 0 ≦ a2 ≦ 0.6, 0 ≦ a1 + a2 ≦ 0.4, 0.1 ≦ B ≦ 0.6, 0.1 ≦ C ≦ 0.45, 0 ≦ D ≦ 0.6, 0 ≦ E ≦ 0.6, and 0 ≦ F ≦ 0.2. Note that A1 + A2 + A3 + A4 + a1 + a2 + B + C + D + E + F = 1.

[0185] The weight average molecular weight (Mw) of polymer P is preferably 1000 to 500000, more preferably 3000 to 100000. If Mw is within this range, sufficient etching resistance can be obtained, and there is no risk of a decrease in resolution due to the inability to ensure the difference in dissolution rate before and after exposure. In the present invention, Mw is a polystyrene equivalent measurement value by gel permeation chromatography (GPC) using THF or N,N-dimethylformamide (DMF) as a solvent.

[0186] Furthermore, when the molecular weight distribution (Mw / Mn) of the polymer P is broad, low-molecular-weight and high-molecular-weight polymers are present, which may result in foreign matter being found on the pattern or deterioration of the pattern shape after exposure. Therefore, since the effect of Mw / Mn tends to become greater as the pattern rule becomes finer, in order to obtain a resist composition that is suitable for use with fine pattern dimensions, it is preferable that the Mw / Mn of the polymer has a narrow distribution of 1.0 to 2.0.

[0187] To synthesize the polymer P, for example, a monomer that gives the repeating unit described above may be polymerized by heating in an organic solvent together with a radical polymerization initiator.

[0188] Examples of the organic solvent used during polymerization include toluene, benzene, THF, diethyl ether, dioxane, cyclohexane, cyclopentane, methyl ethyl ketone (MEK), propylene glycol monomethyl ether acetate (PGMEA), and γ-butyrolactone (GBL). Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl-2,2-azobis(2-methylpropionate), 1,1'-azobis(1-acetoxy-1-phenylethane), benzoyl peroxide, and lauroyl peroxide. The amount of these initiators added is preferably 0.01 to 25 mol% based on the total amount of monomers to be polymerized. The reaction temperature is preferably 50 to 150°C, and more preferably 60 to 100°C. The reaction time is preferably 2 to 24 hours, and more preferably 2 to 12 hours from the viewpoint of production efficiency.

[0189] The polymerization initiator may be added to the monomer solution and then fed to the reaction vessel, or an initiator solution may be prepared separately from the monomer solution and then fed to the reaction vessel independently. Since there is a possibility that the polymerization reaction proceeds due to radicals generated from the initiator during the waiting time, resulting in the formation of a super-polymer, it is preferable to prepare the monomer solution and the initiator solution independently and dropwise feed them from the viewpoint of quality control. The acid labile group introduced into the monomer may be used as is, or may be protected or partially protected after polymerization. In addition, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used in combination to adjust the molecular weight. In this case, the amount of these chain transfer agents added is preferably 0.01 to 20 mol% based on the total amount of monomers to be polymerized.

[0190] In the case of a monomer containing a hydroxy group, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid, such as an ethoxyethoxy group, during polymerization, and then deprotected with a weak acid and water after polymerization; alternatively, the hydroxy group may be substituted with an acetyl group, a formyl group, a pivaloyl group, or the like, and then subjected to alkaline hydrolysis after polymerization.

[0191] When hydroxystyrene or hydroxyvinylnaphthalene is copolymerized, hydroxystyrene or hydroxyvinylnaphthalene may be polymerized by heating with another monomer in an organic solvent after adding a radical polymerization initiator, or acetoxystyrene or acetoxyvinylnaphthalene may be used and, after polymerization, the acetoxy group may be deprotected by alkaline hydrolysis to give polyhydroxystyrene or hydroxypolyvinylnaphthalene.

[0192] As the base for the alkaline hydrolysis, ammonia water, triethylamine, etc. can be used. The reaction temperature is preferably −20 to 100° C., more preferably 0 to 60° C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0193] The amount of each monomer in the monomer solution may be appropriately set so as to obtain the preferred content ratio of the repeating units described above.

[0194] The polymer obtained by the above-mentioned production method may be a reaction solution obtained by a polymerization reaction as a final product, or a powder obtained through a purification process such as a reprecipitation method in which a polymerization solution is added to a poor solvent to obtain a powder, and the resulting product may be treated as a final product. However, from the viewpoint of work efficiency and quality stabilization, it is preferable to treat the polymer solution obtained by dissolving the powder obtained by the purification process in a solvent as a final product. Specific examples of the solvent used in this case include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol, as described in paragraphs

[0144] to

[0145] of JP-A-2008-111103, propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether. ethers such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, and esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, propylene glycol mono tert-butyl ether acetate, and esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, butyl acetate, tert-butyl propionate, propylene glycol monoethyl ...

[0195] The concentration of the polymer in the polymer solution is preferably from 0.01 to 30% by mass, more preferably from 0.1 to 20% by mass.

[0196] The reaction solution or polymer solution is preferably filtered through a filter, which is effective in stabilizing the quality since it can remove foreign matter or gel that may cause defects.

[0197] The material of the filter used in the filter filtration includes fluorocarbon, cellulose, nylon, polyester, and hydrocarbon materials, but in the filtration process of the resist composition, a filter formed of a fluorocarbon, so-called Teflon (registered trademark), a hydrocarbon such as polyethylene or polypropylene, or nylon is preferred. The pore size of the filter can be appropriately selected according to the target cleanliness, but is preferably 100 nm or less, more preferably 20 nm or less. In addition, these filters may be used alone, or multiple filters may be used in combination. The filtration method may be to pass the solution only once, but it is more preferable to circulate the solution and perform filtration multiple times. The filtration process can be performed in any order and number of times in the polymer production process, but it is preferable to filter the reaction solution after the polymerization reaction, the polymer solution, or both.

[0198] The polymer P may include two or more polymers having different composition ratios, Mw, and molecular weight distributions.

[0199] [(B) Crosslinker X] The crosslinking agent X of component (B) is a melamine compound, a glycoluril compound, a urea compound, or an epoxy compound substituted with at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group. These may be used as additives or may be introduced as pendant groups into the polymer side chain.

[0200] Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated or a mixture thereof, and the like.

[0201] Examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound or mixture thereof in which 1 to 4 methylol groups of tetramethylol glycoluril are methoxymethylated, and a compound or mixture thereof in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated.

[0202] Examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated, or a mixture thereof, and tetramethoxyethyl urea.

[0203] Examples of the epoxy compound include tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0204] In the chemically amplified negative resist composition of the present invention, the content of the crosslinking agent X is preferably from 0.1 to 50 parts by mass, and more preferably from 1 to 40 parts by mass, relative to 100 parts by mass of the base polymer.

[0205] [(C) Onium salt type quencher] The chemically amplified negative resist composition of the present invention may contain an onium salt quencher as component (C). Examples of the onium salt quencher as component (C) include onium salts represented by the following formula (Q1) or (Q2). In the present invention, a quencher refers to a material that traps the acid generated by the photoacid generator in the chemically amplified resist composition, thereby preventing the acid from diffusing into unexposed areas and forming a desired pattern. [ka]

[0206] In formula (Q1), R 31 represents a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. 32 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom.

[0207] R 31 Specific examples of the hydrocarbyl group having 1 to 40 carbon atoms represented by the formula (1) include alkyl groups having 1 to 40 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as decyl group and adamantyl group; aryl groups having 6 to 40 carbon atoms, such as phenyl group, naphthyl group and anthracenyl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms and halogen atoms, and the -CH2 A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0208] R 32 Specific examples of the hydrocarbyl group represented by the formula: 31 In addition to the specific examples of the substituents given above, examples include fluorinated saturated hydrocarbyl groups such as a trifluoromethyl group and a trifluoroethyl group, and fluorinated aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0209] Specific examples of the anion of the onium salt represented by formula (Q1) include, but are not limited to, those shown below. [ka]

[0210] [ka]

[0211] [ka]

[0212] Specific examples of the anion of the onium salt represented by formula (Q2) include, but are not limited to, those shown below. [ka]

[0213] [ka]

[0214] [ka]

[0215] In formulas (Q1) and (Q2), Mq + is an onium cation. The onium cation is preferably a sulfonium cation represented by the above formula (cation-1), an iodonium cation represented by the above formula (cation-2), or an ammonium cation represented by the following formula (cation-3). [ka]

[0216] In formula (cation-3), R ct6 ~R ct9 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. ct6 and R ct7 and may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded. As the hydrocarbyl group, R ct1 ~R ct5 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0217] Examples of the ammonium cation represented by formula (cation-3) include, but are not limited to, those shown below. [ka]

[0218] Specific examples of the onium salt represented by formula (Q1) or (Q2) include any combination of the above-mentioned anions and cations. These onium salts can be easily prepared by ion exchange reaction using known organic chemical methods. For ion exchange reaction, refer to, for example, JP-A-2007-145797.

[0219] The onium salt represented by formula (Q1) or (Q2) acts as a quencher in the chemically amplified resist composition of the present invention. This is because each counter anion of the onium salt is a conjugate base of a weak acid. The weak acid here means an acidity that cannot deprotect the acid labile group of the acid labile group-containing unit used in the base polymer. The onium salt represented by formula (Q1) or (Q2) functions as a quencher when used in combination with an onium salt-type photoacid generator having a conjugate base of a strong acid such as a sulfonic acid whose α-position is fluorinated as a counter anion. That is, when an onium salt that generates a strong acid such as a sulfonic acid whose α-position is fluorinated and an onium salt that generates a weak acid such as a non-fluorinated sulfonic acid or carboxylic acid are mixed and used, when the strong acid generated from the photoacid generator by irradiation with high energy rays collides with an onium salt having an unreacted weak acid anion, the weak acid is released by salt exchange to generate an onium salt having a strong acid anion. In this process, the strong acid is exchanged for a weaker acid with a lower catalytic activity, and the acid appears to be deactivated, thereby enabling control of acid diffusion.

[0220] Here, when the photoacid generator that generates a strong acid is an onium salt, the strong acid generated by irradiation with high energy rays can be exchanged for a weak acid as described above, but on the other hand, it is considered that the weak acid generated by irradiation with high energy rays collides with the onium salt that generates the unreacted strong acid and is unlikely to undergo salt exchange. This is due to the phenomenon that the onium cation is more likely to form an ion pair with the anion of the strong acid.

[0221] When the chemically amplified resist composition of the present invention contains an onium salt type quencher (C), the content is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, relative to 80 parts by mass of the polymer P (A). If the content of the onium salt type quencher (C) is within the above range, the resolution is good and the sensitivity is not significantly reduced, which is preferable. The onium salt type quencher (C) may be used alone or in combination of two or more kinds.

[0222] [(D) Organic solvent] The chemically amplified negative resist composition of the present invention may contain an organic solvent as component (D). There are no particular limitations on the organic solvent for component (D) as long as it is capable of dissolving the components described above and below. Examples of such organic solvents include ketones such as cyclopentanone, cyclohexanone, and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ketoalcohols such as DAA; ethers such as PGME, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono tert-butyl ether acetate; lactones such as GBL; and mixed solvents thereof. When a polymer containing an acetal-based acid labile group is used, a high-boiling alcohol solvent, specifically, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, or the like can be added to accelerate the deprotection reaction of the acetal.

[0223] Among these organic solvents, 1-ethoxy 2-propanol, PGMEA, cyclohexanone, GBL, DAA and mixed solvents thereof, which have particularly excellent solubility for the polymer P of the component (A), are preferred.

[0224] When the chemically amplified resist composition of the present invention contains the organic solvent (D), the content thereof is preferably 200 to 5000 parts by mass, and more preferably 400 to 3000 parts by mass, relative to 80 parts by mass of the polymer P (A). The organic solvent (D) may be used alone or in combination of two or more kinds.

[0225] [(E) Surfactant] The chemically amplified negative resist composition of the present invention may contain a surfactant as component (E) in addition to the above-mentioned components. Examples of the surfactant include those described in paragraphs

[0165] to

[0166] of JP-A-2008-111103. By adding a surfactant, the coatability of the resist composition can be further improved or controlled. When the chemically amplified negative resist composition of the present invention contains the surfactant (E), the content thereof is preferably 0.0001 to 10 parts by mass relative to 100 parts by mass of the base polymer. The surfactant may be used alone or in combination of two or more types.

[0226] The chemically amplified negative resist composition of the present invention has a high dissolution contrast of the resist film due to an optimal deprotection reaction, a high effect of suppressing acid diffusion, high resolution, exposure margin, excellent process adaptability, a good pattern shape after exposure, and excellent etching resistance. Therefore, due to these excellent properties, it is extremely useful and is very effective as a material for forming a mask pattern.

[0227] [Pattern formation method] The pattern forming method of the present invention includes the steps of forming a resist film on a substrate using the above-mentioned chemically amplified negative resist composition, exposing the resist film to high-energy radiation, and developing the exposed resist film using an organic solvent developer.

[0228] The substrate may be, for example, a substrate for manufacturing integrated circuits (Si, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.), or substrates for mask circuit manufacturing (Cr, CrO, CrON, MoSi 2 , SiO 2 etc.) can be used.

[0229] The resist film can be formed, for example, by applying the chemically amplified resist composition onto a substrate by a method such as spin coating so that the film thickness is preferably 0.05 to 2 μm, and then pre-baking the composition on a hot plate, preferably at 60 to 150° C. for 1 to 10 minutes, more preferably at 80 to 140° C. for 1 to 5 minutes.

[0230] Examples of high energy rays used for exposing the resist film include i-rays, KrF excimer laser light, ArF excimer laser light, electron beams (EB), EUV, etc. When i-rays, KrF excimer laser light, ArF excimer laser light, or EUV is used for exposure, a mask for forming a desired pattern is used, and the exposure amount is preferably 1 to 200 mJ / cm. 2 , more preferably 10 to 100 mJ / cm 2 When EB is used, the exposure dose is preferably 1 to 300 μC / cm 2 , either directly or through a mask for forming a desired pattern. 2 , more preferably 10 to 200 μC / cm 2 Irradiate so that

[0231] In addition to the usual exposure method, the immersion method can be used in which a liquid with a refractive index of 1.0 or more is placed between the resist film and the projection lens. In this case, a water-insoluble protective film can also be used.

[0232] After the exposure, PEB may be performed, for example, by heating on a hot plate at preferably 60 to 150° C. for 1 to 5 minutes, more preferably 90 to 130° C. for 1 to 3 minutes.

[0233] As the organic solvent developer, it is preferable to select a solvent having a solubility parameter (SP value) close to that of the base polymer, and polar solvents such as ketone-based solvents, ester-based solvents, alcohol-based solvents, ether-based solvents, and amide-based solvents, and hydrocarbon-based solvents can be used.

[0234] Examples of the ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate.

[0235] Examples of the ester-based solvents include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate, 3-methy-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, and propyl lactate.

[0236] Examples of the alcohol-based solvent include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol, 4-methyl-2-pentanol, n-heptyl alcohol, n-octyl alcohol, and n-decanol; glycol-based solvents such as ethylene glycol, diethylene glycol, and triethylene glycol; and glycol ether-based solvents such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and methoxymethylbutanol.

[0237] Examples of the ether-based solvent include the glycol ether-based solvents, as well as dioxane and tetrahydrofuran.

[0238] As the amide-based solvent, for example, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, hexamethylphosphoric triamide, 1,3-dimethyl-2-imidazolidinone, etc. can be used.

[0239] Examples of the hydrocarbon solvent include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as pentane, hexane, octane, and decane.

[0240] These organic solvents may be used alone or in combination of two or more.

[0241] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by piling up the developer on the substrate surface by surface tension and leaving it still for a certain period of time (paddle method), a method of spraying the developer on the substrate surface (spray method), and a method of continuously dispensing the developer while scanning a developer dispensing nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method). There is no particular limit to the time for developing the pattern, but it is preferably 10 to 90 seconds. EXAMPLES

[0242] The present invention will be specifically described below with reference to Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples.

[0243] [1] Synthesis of monomer [Synthesis Example 1-1] Synthesis of Monomer MB-1 [ka]

[0244] (1) Synthesis of intermediate In-1 A Grignard reagent was prepared from magnesium (160.5 g), 4-bromobenzene (1155 g) and THF (3300 g) under a nitrogen atmosphere. A solution consisting of raw material M-1 (348.5 g) and THF (700 g) was added dropwise while maintaining the internal temperature at 45°C or less. After stirring for 2 hours at an internal temperature of 50°C, the reaction solution was ice-cooled and a mixed aqueous solution of ammonium chloride (660 g) and 3.0 mass% hydrochloric acid aqueous solution (3960 g) was added dropwise to stop the reaction. Toluene (4500 mL) was added, and a normal aqueous work-up was performed. The solvent was distilled off, and the intermediate In-1 was obtained as a colorless oil in an amount of 865 g (yield 94%) by distillation and purification.

[0245] (2) Synthesis of Monomer MB-1 Under a nitrogen atmosphere, methacrylic acid chloride (821 g) was added dropwise to a solution of intermediate In-1 (865 g), triethylamine (1022 g), dimethylaminopyridine (68.5 g) and acetonitrile (3150 mL) at an internal temperature of 60° C. or less. After aging for 20 hours at an internal temperature of 55° C., the reaction solution was cooled on ice and saturated sodium bicarbonate water (2000 mL) was added dropwise to stop the reaction. Extraction was performed with toluene (4200 mL), and after normal aqueous work-up and solvent distillation, reduced pressure distillation was performed to obtain 1012 g of monomer MB-1 as a colorless, transparent oil (yield 81%).

[0246] [Synthesis Example 1-2] Synthesis of Monomer MB-2 [ka]

[0247] (1) Synthesis of intermediate In-2 A Grignard reagent was prepared from magnesium (59 g), 1,4-dichlorobutane (146 g) and THF (1000 mL) under a nitrogen atmosphere. A solution consisting of raw material M-2 (154 g) and THF (150 mL) was added dropwise while maintaining the internal temperature at 50°C or less. After stirring for 2 hours at an internal temperature of 50°C, the reaction solution was ice-cooled and a mixed aqueous solution of ammonium chloride (240 g) and 3.0 mass% hydrochloric acid aqueous solution (1450 g) was added dropwise to stop the reaction. Toluene (800 mL) was added, and a normal aqueous work-up was performed. After the solvent was distilled off, distillation was performed under reduced pressure to obtain 175 g of intermediate In-2 as a colorless, transparent oil (yield 98%).

[0248] (2) Synthesis of Monomer MB-2 Monomer MB-2 was obtained as a colorless, transparent oil (yield 82%) in the same manner as in Synthesis Example 1-1(2), except that intermediate In-2 was used instead of intermediate In-1.

[0249] [Synthesis Examples 1-3 to 1-4] Synthesis of Monomers MB-3 and MB-4 Using the corresponding raw materials, the monomers MB-3 and MB-4 shown below were synthesized. [ka]

[0250] [Comparative Synthesis Examples 1-1 to 1-3] Synthesis of Comparative Monomers MBX-1 to MBX-3 Comparative monomers MBX-1 to MBX-3 were synthesized using the corresponding raw materials. [ka]

[0251] [2] Polymer synthesis Among the monomers used in the synthesis of the polymer, those other than the monomers MB-1 to MB-4 and the comparative monomers MBX-1 to MBX-4 are as follows. [ka]

[0252] [ka]

[0253] [Synthesis Example 2-1] Synthesis of Polymer P-1 In a nitrogen atmosphere, monomer MB-1 (50.1 g), monomer MC-1 (24.8 g), monomer MA-1 (38.0 g), 3.96 g of V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 127 g of MEK were placed in a flask to prepare a monomer-polymerization initiator solution. 46 g of MEK was placed in another flask in a nitrogen atmosphere, and the mixture was heated to 80° C. with stirring, and then the monomer-polymerization initiator solution was dropped over 4 hours. After the dropwise addition, the temperature of the polymerization liquid was kept at 80° C. and stirring was continued for 2 hours, and then cooled to room temperature. The obtained polymerization liquid was dropped into 2000 g of vigorously stirred hexane, and the precipitated polymer was filtered off. Furthermore, the obtained polymer was washed twice with 600 g of hexane, and then vacuum dried at 50° C. for 20 hours to obtain a white powdery polymer P-1 (yield 98.1 g, yield 98%). Polymer P-1 had an Mw of 10,900 and an Mw / Mn ratio of 1.82. Note that Mw was a value measured in terms of polystyrene by GPC using DMF as a solvent. [ka]

[0254] [Synthesis Examples 2-2 to 2-13, Comparative Synthesis Examples 2-1 to 2-6] Synthesis of polymers P-2 to P-13 and comparative polymers CP-1 to CP-6 Except for changing the type and compounding ratio of each monomer, the polymers shown in Tables 1 and 2 were synthesized in the same manner as in Synthesis Example 2-1. In Tables 1 and 2, the incorporation ratios are in mol %.

[0255] [Table 1]

[0256] [Table 2]

[0257] [3] Preparation and evaluation of chemically amplified resist compositions (1) Preparation of Chemically Amplified Resist Composition [Examples 1-1 to 1-22, Comparative Examples 1-1 to 1-8] Polymer P (P-1 to P-13), comparative polymers (CP-1 to CP-6), photoacid generator (PAG-1), and quencher (Q-1 to Q-4) were dissolved in a solvent containing 50 ppm of Omnova's PolyFox PF-636 as a surfactant, according to the compositions shown in Tables 3 and 4 below, and the resulting solution was filtered through a 0.2 μm Teflon (registered trademark) filter to prepare chemically amplified resist compositions.

[0258] In Tables 3 and 4, the components are as follows. Photoacid generator: PAG-1 [ka]

[0259] Quencher: Q-1~Q-4 [ka]

[0260] Crosslinking agent: X-1~X-4 [ka]

[0261] Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (Diacetone Alcohol) EL (Ethyl lactate)

[0262] [Table 3]

[0263] [Table 4]

[0264] (2) Crosslinking reactivity evaluation [Examples 2-1 to 2-23, Comparative Examples 2-1 to 2-2] Resist compositions R-1 to R-21 and CR-7 to CR-8 were each spin-coated onto a Si substrate and pre-baked for 60 seconds using a hot plate at the temperatures shown in Tables 5 and 6 to form a resist film with a thickness of 50 nm. 2 After performing PEB for 60 seconds on a hot plate at the temperatures shown in Tables 5 and 6, the film was peeled off from the substrate and dissolved in an organic solvent, and the weight average molecular weight in terms of polystyrene was measured by gel permeation chromatography (GPC) using DMF as the solvent. The results are shown in Tables 5 and 6.

[0265] [Table 5]

[0266] [Table 6]

[0267] From the results shown in Tables 5 and 6, in Examples 2-1 to 2-23, which used resist compositions R-1 to R-21 containing a crosslinking agent, the average molecular weight after exposure was increased compared to Comparative Examples 2-1 to 2-2, which used resist compositions CR-7 to CR-8 not containing a crosslinking agent, indicating that the crosslinking reaction had progressed. Note that in Example 2-23, in which the PEB temperature was set higher, crosslinking had occurred to such an extent that the resist film after prebaking was insoluble in a GPC solvent.

[0268] (3) Dissolution contrast evaluation [Examples 3-1 to 2-23, Comparative Examples 3-1 to 3-8] Resist compositions R-1 to R-21 and CR-1 to CR-8 were spin-coated on an anti-reflective film DUV-42 manufactured by Nissan Chemical Industries, Ltd., which was prepared on an 8-inch wafer with a thickness of 61 nm, and pre-baked for 60 seconds using a hot plate to prepare a resist film with a thickness of 50 nm. This was exposed using a KrF exposure machine (Nikon Corporation S206D), and PEB was performed for 60 seconds on a hot plate at the temperatures shown in Tables 7 and 8, and development was performed for 30 seconds using butyl acetate as a developer. The resist film thickness after this development process was measured, and the relationship between the exposure dose and the resist film thickness after development process was plotted to analyze the dissolution contrast. Furthermore, the contrast was evaluated according to the following criteria. In addition, a film thickness meter VM-2210 manufactured by Hitachi High-Technologies Corporation was used to measure the film thickness. In addition, the presence or absence of dissolution residue in the unexposed area after development with butyl acetate was evaluated according to two criteria: present / absent. The results are shown in Tables 7 and 8.

[0269] As representative compositions in the dissolution contrast evaluation, the contrast curves of the resist films of Examples 3-17 and Comparative Examples 3-7 are shown in FIG. 1. The vertical axis in FIG. 1 is the film thickness after development normalized by the film thickness before development. The contrast values ​​in Table 7 represent the slope of the film thickness change with respect to the exposure dose at the point where the solubility of the resist film in the developer changes rapidly. In the section from when the film thickness is 8% or more of the initial film thickness to when the film thickness is 60% or less of the initial film thickness, the horizontal axis is the logarithm of the exposure dose and the vertical axis is the normalized film thickness. The contrast of the resist film formed from each resist composition was evaluated as follows based on the absolute value of the contrast value. (Judgment criteria) ◎: Absolute contrast value is 10 or more ○: Absolute contrast value is 5 or more and less than 10 ×: Absolute contrast value is less than 5

[0270] [Table 7]

[0271] [Table 8]

[0272] From the results shown in FIG. 1, it was confirmed that the difference in solubility between the exposed and unexposed parts of Example 3-17 was significantly different from that of Comparative Example 3-7, and that the change in film thickness after development processing with respect to the amount of exposure was steep. In addition, it was also confirmed that the organic solvent solubility of the exposed part was also very low, and the film loss after exposure was greatly improved. The contrast values ​​in Tables 7 and 8 represent the slope of this film thickness change, with a positive slope for negative resists and a negative slope for positive resists. In addition, the larger the absolute value, the better the dissolution contrast. All of Examples 3-1 to 3-23 showed good contrast, which is believed to be due to the fact that crosslinking between polymers was promoted by the acid generated in the exposed part. In addition, it was revealed that resists containing a crosslinking agent with more crosslinking sites showed good contrast. In addition, in Comparative Examples 3-1 to 3-4, the film was observed to remain undissolved in the unexposed part, suggesting that having the repeating unit B as an acid labile group is essential for improving solubility in an organic solvent developer.

[0273] (5) EB lithography evaluation [Examples 4-1 to 4-23, Comparative Examples 4-1 to 4-4] Resist compositions R-1 to R-21 and CR-5 to CR-8 were spin-coated on an anti-reflective film DUV-42 manufactured by Nissan Chemical Co., Ltd., which was prepared on an 8-inch wafer with a thickness of 61 nm, and pre-baked for 60 seconds using a hot plate to prepare a resist film with a thickness of about 50 nm. This was exposed using an electron beam lithography device manufactured by Elionix (ELS-F125, acceleration voltage 125 kV), and PEB was performed for 60 seconds on a hot plate at various temperatures, and development was performed with butyl acetate for 30 seconds. The obtained 44 nmP line and space pattern was observed with a length measuring SEM (S9380) manufactured by Hitachi High-Tech Corporation, and the standard deviation (σ) calculated from the results was tripled (3σ) to obtain the pattern width variation (LWR). Furthermore, the pattern width variation was evaluated based on the following criteria. The results are shown in Tables 9 and 10. (Judgment criteria) ◎: LWR value is less than 3.0 ○: LWR value is 3.0 or more and less than 3.5 ×: LWR value is 3.5 or more

[0274] [Table 9]

[0275] [Table 10]

[0276] All of Examples 4-1 to 4-21 showed good LWR. Also, resist films containing a crosslinking agent with more crosslinking sites showed better LWR. Furthermore, Examples 4-22 to 4-23, which had a higher PEB temperature, provided particularly excellent LWR performance. Generally, when the PEB temperature is set to a high temperature above the glass transition point, acid diffusion is promoted and roughness deteriorates. However, in the chemically amplified negative resist composition of the present invention, the glass transition point is improved by crosslinking, and the molecular weight is also increased, so that it is expected that acid diffusibility is greatly suppressed.

[0277] The above results show that the chemically amplified negative resist composition of the present invention has high dissolution contrast and good LWR, and therefore has small edge roughness and dimensional variation, excellent resolution, and a good pattern shape after exposure.

Claims

1. (A) a polymer P including a repeating unit represented by any one of the following formulas (A1) to (A4) which generates an acid upon exposure, a repeating unit represented by formula (B) which is decomposed by the action of an acid to change the solubility in a developer, and a repeating unit having a phenolic hydroxy group represented by the following formula (C); (B) a crosslinking agent X which is a melamine compound, a glycoluril compound, a urea compound or an epoxy compound substituted with at least one group selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group; A chemically amplified negative resist composition comprising: 【Chemistry 1】 (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 is a single bond or a phenylene group. X 2 is *-C(=O)-O-X 21 -, *-C(=O)-NH-X 21 - or *-O-X 21 - is. 21 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. X 3 each independently represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X 31 - is. 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the aliphatic hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond and a lactone ring. X 4 each independently represents a single bond or *-X 41 -C(=O)-O-. X 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. X 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-C(=O)-O-X 51 -, *-C(=O)-N(H)-X 51 - or *-O-X 51 - is. 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * indicates a bond to a carbon atom in the main chain. R 1 and R 2 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 1 and R 2 and may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L 1 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. a is an integer from 0 to 3. 【Chemistry 2】 (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y 1 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-Y 11 - is. 11 represents an aliphatic hydrocarbylene group having 1 to 20 carbon atoms, a phenylene group, or a naphthylene group, and the hydrocarbylene group may contain at least one type selected from a hydroxy group, an ether bond, an ester bond, and a lactone ring. * represents a bond to a carbon atom of the main chain. R B and R C are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom; R B and R C may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 11 is a fluorine atom, a fluorinated saturated hydrocarbyl group having 1 to 5 carbon atoms, or a fluorinated saturated hydrocarbyloxy group having 1 to 5 carbon atoms. R 12 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. b1 is an integer from 0 to 2. b2 is an integer from 0 to 5. b3 is an integer from 0 to 2. 【Chemistry 3】 (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y 2 is a single bond or *-C(=O)-O-. * represents a bond to a carbon atom in the main chain. R 21 represents a halogen atom, a cyano group, a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbyloxy group having 1 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms which may contain a heteroatom, or a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms which may contain a heteroatom. c1 is an integer from 1 to 4. c2 is an integer from 0 to 4, provided that 1≦c1+c2≦5.

2. 2. The chemically amplified negative resist composition according to claim 1, wherein b1 is 1 or 2.

3. 2. The chemically amplified negative resist composition according to claim 1, wherein the polymer P further comprises a repeating unit containing a lactone ring.

4. The resist composition according to claim 1, further comprising an onium salt quencher represented by the following formula (Q1) or (Q2): 【Chemistry 4】 (In the formula, R 31 represents a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom, except for those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group. R 32 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. Mq + is an onium cation.

5. 2. The chemically amplified negative resist composition according to claim 1, further comprising an organic solvent.

6. 2. The chemically amplified negative resist composition according to claim 1, further comprising a surfactant.

7. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified negative resist composition according to any one of claims 1 to 6; exposing the resist film to high-energy radiation; and developing the exposed resist film using a developer containing an organic solvent.

8. 8. The method for forming a pattern according to claim 7, further comprising a step of heating the resist film after exposure and before development.

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