Onium salt type monomer, polymer, chemically amplified resist composition, and pattern forming method

Abstract

To provide an onium salt type monomer for a chemically amplified resist composition which has excellent solvent solubility and high sensitivity and contrast in photolithography using high-energy radiation, and is excellent in lithographic performance such as exposure tolerance (EL), LWR, CDU and depth of focus (DOF), and is also excellent in resistance to pattern collapse and etching resistance even in fine pattern formation; a polymer comprising a repeating unit derived from the onium salt type monomer; a chemically amplified resist composition comprising the polymer; and a pattern formation method using the chemically amplified resist composition.SOLUTION: The present invention provides an onium salt type monomer represented by the following formula (a).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an onium salt type monomer, a polymer, a chemically amplified 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. In particular, the expansion of the flash memory market and the increase in memory capacity are driving this miniaturization. The most advanced miniaturization technology is ArF lithography, which is used to mass-produce 65nm node devices, and preparations are underway to mass-produce 45nm node devices using next-generation ArF immersion lithography. As for the next-generation 32nm node devices, immersion lithography using ultra-high NA lenses that combine a liquid with a higher refractive index than water, a high refractive index lens, and a high refractive index resist film, extreme ultraviolet (EUV) lithography with a wavelength of 13.5nm, and double exposure (double patterning lithography) of ArF lithography are candidates that are being considered and are being considered.

[0003] As miniaturization progresses and approaches the diffraction limit of light, the optical contrast decreases, which in turn causes a decrease in the resolution of hole and trench patterns and a decrease in the focus margin in positive resist films.

[0004] As patterns become finer, line width roughness (LWR) of line patterns and dimension uniformity (CDU) of hole patterns become problems. The influence of uneven distribution and aggregation of base polymers and acid generators, and the influence of acid diffusion have been pointed out. Furthermore, as the resist film becomes thinner, the LWR tends to increase, and the deterioration of LWR due to the thinning that accompanies the progress of finer patterns has become a serious problem.

[0005] Resist compositions for EUV lithography must simultaneously achieve high sensitivity, high resolution, and low LWR. Shortening the acid diffusion distance reduces LWR but reduces sensitivity. For example, lowering the post-exposure bake (PEB) temperature reduces LWR but reduces sensitivity. Increasing the amount of quencher added also reduces LWR but reduces sensitivity. It is necessary to break the trade-off between sensitivity and LWR.

[0006] In order to suppress acid diffusion, a resist compound 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-bonded acid generators are characterized by a very short acid diffusion because polymeric 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 additive-type acid generator, increasing the amount of the additive increases the sensitivity, but in this case, the acid diffusion distance also increases. Since acid diffuses non-uniformly, increased acid diffusion leads to deterioration of LWR and CDU. It can be said that polymer-type acid generators have high capabilities in terms of the balance between sensitivity, LWR, and CDU.

[0007] Iodine atoms have a very high absorption of EUV light with a wavelength of 13.5 nm, and it has been confirmed that iodine atoms generate secondary electrons during exposure, which has attracted attention in EUV lithography. Patent Document 2 describes a photoacid generator in which an iodine atom is introduced into an anion, and Patent Document 3 describes a polymerizable group-containing photoacid generator in which an iodine atom is introduced into an anion. Although it has been confirmed that these improve lithography performance to a certain extent, iodine atoms are not highly soluble in organic solvents, and there is a concern that they may precipitate in the solvent. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4425776 [Patent Document 2] Patent No. 6720926 [Patent Document 3] Patent No. 6973274 Summary of the Invention [Problem to be solved by the invention]

[0009] There is a demand for the development of a resist composition that uses an acid as a catalyst for chemical amplification, which has even higher sensitivity, is capable of improving line LWR and hole CDU, and also has excellent etching resistance after pattern formation.

[0010] The present invention has been made in view of the above circumstances, and has an object to provide an onium salt-type monomer for use in a chemically amplified resist composition which has excellent solvent solubility, high sensitivity, high contrast, and excellent lithographic performance such as exposure tolerance (EL), LWR, CDU, and depth of focus (DOF), and which is also resistant to pattern collapse and has excellent etching resistance even in the formation of fine patterns, particularly in photolithography using high-energy rays such as KrF excimer laser light, ArF excimer laser light, electron beam (EB), and EUV, a polymer containing a repeating unit derived from the onium salt-type monomer, a chemically amplified resist composition containing the polymer, and a pattern formation method using the chemically amplified resist composition. [Means for solving the problem]

[0011] As a result of intensive research into achieving the above-mentioned object, the present inventors have found that by using, as a polymer-bonded acid generator, a polymer that has a styrene or vinylnaphthalene structure as a polymerizable group and that contains a repeating unit derived from an onium salt that contains a fluorosulfonate anion having an aromatic ring structure substituted with an iodine atom, it is possible to obtain a chemically amplified resist composition that has high sensitivity, improved LWR and CDU, high contrast and high resolution, and excellent etching resistance, and have completed the present invention.

[0012] That is, the present invention provides the following onium salt type monomer, polymer, chemically amplified resist composition, and pattern forming method. 1. An onium salt monomer represented by the following formula (a): [ka] (In the formula, n1 is 0 or 1. n2 is 0 or 1. n3 is an integer from 0 to 4. n4 is an integer from 0 to 4. n5 is an integer from 1 to 6, with the proviso that when n2 is 0, 1≦n4+n5≦4, and when n2 is 1, 1≦n4+n5≦6. n6 is an integer from 0 to 4. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. When n3 is 2, 3 or 4, a plurality of R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than an iodine atom or a heteroatom. When n4 is 2, 3 or 4, a plurality of R 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L A , L B and L C are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a sulfonate amide bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. Q 1 and Q 2 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Q 3 and Q 4are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z + is an onium cation. 2. An onium salt type monomer of formula 1, which is represented by the following formula (a1): [ka] (In the formula, n1~n6, R A , R 1 , R 2 , L A , L C , Q 1 ~Q 4 and Z + is the same as above.) 3. An onium salt type monomer of formula 2, which is represented by the following formula (a2): [ka] (In the formula, n1~n6, R A , R 1 , R 2 , L A , Q 1 , Q 2 and Z + is the same as above.) 4.Z + is a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka] (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 5. A polymer containing a repeating unit derived from any one of the onium salt monomers 1 to 4. 6. The polymer of 5 further comprising a repeating unit represented by the following formula (b1) or (b2): [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, a phenylene group, a naphthylene group, *-C(=O)-OX 11 - or -C(=O)-NH-X 11 -, and the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * indicates a bond to a carbon atom in the main chain. AL 1 and A.L. 2 are each independently an acid labile group. R 11 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. a is an integer from 0 to 4. 7. The polymer of 5 or 6 further comprising a repeating unit represented by the following formula (c1): [ka] (In the formula, R Ais a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y 1 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 21 represents a halogen atom, a nitro group, 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. c is an integer between 1 and 4. d is an integer between 0 and 3. However, 1≦c+d≦5. 8. A polymer according to any one of 5 to 7, further comprising a repeating unit represented by the following formula (d1): [ka] (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -, or the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. * represents a bond to a carbon atom of the main chain. Z 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. R 31is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic 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)-). 9. (A) A chemically amplified resist composition comprising a base polymer containing any one of the polymers 5 to 8. 10. The chemically amplified resist composition of 9 further comprising (B) an organic solvent. 11. The chemically amplified resist composition of 9 or 10, further comprising (C) a quencher. 12. Any one of the chemically amplified resist compositions 9 to 11, further comprising (D) an acid generator. 13. Any one of the chemically amplified resist compositions of 9 to 12, further comprising (E) a surfactant. 14. Any one of the chemically amplified resist compositions 9 to 13, further comprising (F) a dissolution inhibitor. 15. A pattern forming method comprising the steps of forming a resist film on a substrate using any one of the chemically amplified resist compositions according to any one of claims 9 to 14, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer. 16. The pattern formation method according to 15, wherein the high-energy radiation is ArF excimer laser light having a wavelength of 193 nm or KrF excimer laser light having a wavelength of 248 nm, EB or EUV having a wavelength of 3 to 15 nm. Effect of the Invention

[0013] A resist film containing a polymer containing a repeating unit derived from an onium salt type monomer represented by formula (a) has a good solvent solubility and is characterized by small acid diffusion due to the large atomic weight of the iodine atom. This makes it possible to prevent a decrease in resolution due to blurring caused by acid diffusion, and improve LWR and CDU. In addition, since the absorption of EUV with a wavelength of 13.5 nm by iodine atoms is very large, secondary electrons are generated from iodine atoms during exposure, resulting in high sensitivity. This makes it possible to construct a chemically amplified resist composition that is highly sensitive and has improved LWR and CDU. In addition, aromatic rings act as good etching resistance groups, making them suitable for fine pattern formation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] [Onium salt type monomer] The onium salt monomer of the present invention is represented by the following formula (a). [ka]

[0015] In formula (a), n1 is 0 or 1. When n1 is 0, it is a benzene ring, and when n1 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, n1 is preferably a benzene ring of 0. n2 is 0 or 1. When n2 is 0, it is a benzene ring, and when n2 is 1, it is a naphthalene ring, but from the viewpoint of solvent solubility, n2 is preferably a benzene ring of 0. n3 is an integer of 0 to 4. From the viewpoint of raw material procurement, n3 is preferably 0, 1 or 2, and more preferably 0 or 1. n4 is an integer of 0 to 4, but is preferably 0, 1, 2 or 3, more preferably 0, 1 or 2, and even more preferably 0 or 1. n5 is an integer of 1 to 6. The more iodine atoms in the anion structure, the higher the absorption, especially against EUV, but there is a concern that the solvent solubility is poor and precipitation occurs in the resist composition, so n5 is preferably 1, 2 or 3, and more preferably 1 or 2. However, when n2 is 0, 1≦n4+n5≦4, and when n2 is 1, 1≦n4+n5≦6. n6 is an integer of 0 to 4, preferably 0, 1, 2 or 3, and more preferably 1.

[0016] In formula (a), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Among these, a hydrogen atom or a methyl group is preferred, and a hydrogen atom is more preferred.

[0017] In formula (a), the iodine atom in the aromatic ring of the anion is L B Since the iodine atom is an element having a large atomic radius, the rotation of the bond axis between the aromatic ring to which the polymerizable group is bonded and the aromatic ring to which the iodine atom is bonded is suppressed, thereby improving the rigidity of the polymer.

[0018] In formula (a), R 1is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom or an iodine atom, and more preferably a fluorine atom or an iodine atom. 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, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group or an icosyl group; a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methyl Examples of the hydrocarbyl groups include cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl groups; aryl groups having 2 to 20 carbon atoms, such as phenyl and naphthyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these groups. In addition, some or all of the hydrogen atoms of the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen, sulfur, nitrogen, and halogen atoms, 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, may contain a hydroxyl group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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. When n3 is 2, 3, or 4, each R 1 may be the same as or different from each other.

[0019] In addition, when n3 is 2, 3, or 4, multiple R 1 may be bonded to each other to form a ring together with the carbon atom of the aromatic ring to which they are bonded. Specific examples of the ring formed in this case include a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, etc. In addition, some or all of the hydrogen atoms in the ring 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.

[0020] In formula (a), R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than iodine atom or a heteroatom. Specific examples of the halogen atom other than iodine atom include a fluorine atom, a chlorine atom, and a bromine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 1 When n4 is 2, 3 or 4, each R 2 may be the same as or different from each other.

[0021] In addition, when n4 is 2, 3, or 4, multiple R 2 However, they may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0022] In formula (a), L A , L B and L Care each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a sulfonamide bond, a carbonate bond or a carbamate bond. A is preferably a single bond, an ether bond, an ester bond or a sulfonate ester bond, and more preferably an ester bond or a sulfonate ester bond. B is preferably a single bond, an ether bond or an ester bond, and more preferably a single bond. C is preferably a single bond, an ether bond, an ester bond or a sulfonate ester bond, and more preferably an ether bond or an ester bond.

[0023] In formula (a), X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be linear, branched or cyclic, and specific examples thereof include an alkanediyl group, a cyclic saturated hydrocarbylene group, an arylene group, etc. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, etc.

[0024] X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a heteroatom, represented by the following formula, include, but are not limited to, those shown below. In the following formula, * represents L A and L B It is a combination with. [ka]

[0025] [ka]

[0026] [ka]

[0027] [ka]

[0028] Of these, X L -0~X L -22, X L -29~X L -34 and X L -47~X L -58 is preferred.

[0029] From the viewpoint of the rigidity of the resulting polymer, X L is preferably a single bond.

[0030] In formula (a), Q 1 and Q 2 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. As the fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a trifluoromethyl group is preferable.

[0031] In formula (a), Q 3 and Q 4 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. As the fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, a trifluoromethyl group is preferable. 3 and Q 4 is more preferably a fluorine atom.

[0032] In formula (a), -[C(Q 1 )(Q 2 )] n4 -C(Q 3 )(Q 4 )-SO 3 - Specific examples of the partial structure represented by the formula (I) are preferably, but are not limited to, those shown below. In the formula (I), * represents L C Represents a bond with . [ka]

[0033] Of these, Acid-1 to Acid-7 are preferred, and Acid-1 to Acid-3, Acid-6 and Acid-7 are more preferred.

[0034] The onium salt monomer represented by formula (a) is preferably one represented by the following formula (a1). [ka] (In the formula, n1~n6, R A , R 1 , R 2 , L A , L C , Q 1 ~Q 4 and Z + is the same as above.)

[0035] The onium salt monomer represented by formula (a1) is preferably one represented by the following formula (a2). [ka] (In the formula, n1~n6, R A , R 1 , R 2 , L A , Q 1 , Q 2 and Z + is the same as above.)

[0036] Specific examples of the anion of the onium salt monomer represented by formula (a) include, but are not limited to, those shown below. In the following formula, R A and Q 1 is the same as above, and Me is a methyl group. The bonding positions of the various substituents on the aromatic ring may be interchangeable. [ka]

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[0093] In formula (1), Z + is an onium cation. The onium cation is preferably a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka]

[0094] In formulas (cation-1) and (cation-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0095] R ct1 ~R ct5 Specific examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0096] R ct1 ~R ct5The hydrocarbyl group represented by the formula (I) 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, and a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 30 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 30 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 30 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group; aralkyl groups having 7 to 30 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 nitro 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.

[0097] Also, R ct1 and R ct2 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 structure include those represented by the following formulas. [ka] (In the formula, the dashed line represents R ct3 It is a bond with .)

[0098] Specific examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0099] [ka]

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[0125] Specific examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [ka]

[0126] [ka]

[0127] Specific examples of the onium salt monomer represented by formula (a) include any combination of the above-mentioned anions and cations.

[0128] The onium salt monomer represented by formula (a) can be synthesized, for example, by a method similar to that for the sulfonium salt having a polymerizable anion described in Japanese Patent No. 5201363, but is not limited thereto.

[0129] [polymer] The polymer of the present invention contains a repeating unit derived from an onium salt monomer represented by formula (a) (hereinafter also referred to as repeating unit a).

[0130] The polymer of the present invention is a polymer-bound photoacid generator that functions as a photoacid generator in a chemically amplified resist composition and also functions as a base polymer. The structural feature of the polymer of the present invention is that it contains a repeating unit having an onium salt structure that has a benzene or naphthalene structure directly bonded to the main chain, which is derived from the onium salt monomer of the present invention, and contains a fluorosulfonate anion having an aromatic ring structure substituted with an iodine atom. Since iodine atoms have a very high absorption of EUV with a wavelength of 13.5 nm, secondary electrons are generated during exposure, and the energy of the secondary electrons is transferred to the acid generator, promoting decomposition, thereby increasing sensitivity. Polymerizable groups consisting of styrene or vinylnaphthalene structures are more rigid than polymerizable groups such as methacrylic acid esters, and improve the glass transition temperature (Tg) of the polymer. It is considered that the base polymer is regularly arranged by the interaction of aromatic rings within or between base polymers (π-π stacking effect), and resistance to pattern collapse in a developer is exhibited even during fine pattern formation. In addition, in the etching process after the formation of a fine pattern, the aromatic ring directly connected to the main chain exhibits excellent etching resistance. In the aromatic ring substituted with an iodine atom, the iodine atom is preferably substituted at the ortho position of the carbon atom to which the polymerizable group is bonded, and it is expected that the rotation of the bond axis between the aromatic ring of the polymerizable group and the aromatic ring substituted with the iodine atom is suppressed. Therefore, excessive acid diffusion of the generated acid is suppressed, and the LWR of the line pattern and the CDU of the hole pattern are excellent, and it is possible to form a pattern that is resistant to pattern collapse, so that it is particularly suitable as a material for a chemically amplified positive resist composition.

[0131] The polymer may further include a repeating unit represented by the following formula (b1) (hereinafter also referred to as repeating unit b1) or a repeating unit represented by the following formula (b2) (hereinafter also referred to as repeating unit b2). [ka]

[0132] In formulas (b1) and (b2), R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0133] In formula (b1), X 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-OX 11 - or -C(=O)-NH-X 11 -, and the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. 11 represents a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. * represents a bond to a carbon atom of the main chain.

[0134] In formula (b2), X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 11 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. a represents an integer of 0 to 4, and preferably 0 or 1.

[0135] In formulas (b1) and (b2), AL 1 and A.L. 2 are each independently an acid labile group. Specific examples of the acid labile group include, but are not limited to, those described in JP-A-2013-80033 and JP-A-2013-83821.

[0136] Typically, specific examples of the acid labile group include those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, * represents a bond.)

[0137] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, and may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, or an iodine atom. The hydrocarbyl group may be linear, branched, or cyclic. The hydrocarbyl group preferably has 1 to 20 carbon atoms.

[0138] In formula (AL-1), b is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0139] In formula (AL-2), R L3 and R L4 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, or an iodine atom. The hydrocarbyl group may be linear, branched, or cyclic. L2 , R L3 and R L4 Any 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.

[0140] In formula (AL-3), R L5 , R L6 and R L7 are each independently a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a fluorine atom, or an iodine atom. The 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 preferred, and an alicyclic ring is particularly preferred.

[0141] Specific examples of the repeating unit b1 include, but are not limited to, those shown below. A and A.L. 1 is the same as above. [ka]

[0142] [ka]

[0143] [ka]

[0144] [ka]

[0145] [ka]

[0146] [ka]

[0147] [ka]

[0148] Specific examples of the repeating unit b2 include, but are not limited to, those shown below. A and A.L. 2 is the same as above. [ka]

[0149] [ka]

[0150] [ka]

[0151] The base polymer preferably further contains a repeating unit represented by the following formula (c1) (hereinafter also referred to as repeating unit c). [ka]

[0152] In formula (c1), R A Y is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 1 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 21is a halogen atom, a nitro group, 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. c is an integer of 1 to 4. d is an integer of 0 to 3, with the proviso that 1≦c+d≦5.

[0153] Specific examples of the repeating unit c include, but are not limited to, those shown below. A is the same as above. [ka]

[0154] [ka]

[0155] [ka]

[0156] [ka]

[0157] [ka]

[0158] The base polymer preferably further contains a repeating unit represented by the following formula (d1) (hereinafter also referred to as repeating unit d). [ka]

[0159] In formula (d1), 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, *-C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -, or the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. * represents a bond to a carbon atom of the main chain. Z 11 R is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 31 is a group having 1 to 20 carbon atoms and containing at least one structure selected from a hydrogen atom, a hydroxy group other than a phenolic 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)-).

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

[0161] [ka]

[0162] [ka]

[0163] [ka]

[0164]

change

[0165]

change

[0166]

change

[0167]

change

[0168]

change

[0169]

change

[0170]

change

[0171]

change

[0172]

change

[0173]

change

[0174]

change

[0175] [ka]

[0176] As the repeating unit c or d, those having a lactone ring are particularly preferred in ArF lithography, and those having a phenol moiety are preferred in KrF lithography, EB lithography and EUV lithography.

[0177] The polymer may further include a repeating unit having a structure in which a hydroxy group is protected by an acid labile group (hereinafter, also referred to as repeating unit e). The repeating unit e is not particularly limited as long as it has one or more structures in which a hydroxy group is protected, and the protecting group is decomposed by the action of an acid to generate a hydroxy group, but is preferably represented by the following formula (e1). [ka]

[0178] In formula (e1), R A R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 41 R is a (e+1)-valent hydrocarbon group having 1 to 30 carbon atoms which may contain a heteroatom. 42 is an acid labile group. e is an integer of 1 to 4.

[0179] In formula (e1), R 42 The acid labile group represented by the formula (I) may be any group that can be deprotected by the action of an acid to generate a hydroxy group. 42 Although the structure is not particularly limited, an acetal structure, a ketal structure, an alkoxycarbonyl group, an alkoxymethyl group represented by the following formula (e2), and the like are preferred, and an alkoxymethyl group represented by the following formula (e2) is particularly preferred. [ka] (In the formula, * represents a bond. R 43 is a hydrocarbyl group having 1 to 15 carbon atoms.)

[0180] R 42 Examples of the acid-labile group represented by and the alkoxymethyl group represented by the formula (e2) and the repeating unit e are the same as those exemplified in the description of the repeating unit d described in JP-A-2020-111564.

[0181] The base polymer may further contain a repeating unit f derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene or a derivative thereof. Specific examples of the monomer that gives the repeating unit f include, but are not limited to, those shown below. [Chemical formula]

[0182] The base polymer may further contain a repeating unit g derived from styrene, indane, vinylpyridine or vinylcarbazole.

[0183] In the polymer of the present invention, the content ratios of the repeating units a, b1, b2, c, d, e, f, and g are preferably 0 < a ≤ 0.4, 0 < b1 ≤ 0.8, 0 ≤ b2 ≤ 0.8, 0 < c ≤ 0.6, 0 ≤ d ≤ 0.6, 0 ≤ e ≤ 0.3, 0 ≤ f ≤ 0.3, and 0 ≤ g ≤ 0.3, and more preferably 0 < a ≤ 0.3, 0 < b1 ≤ 0.7, 0 ≤ b2 ≤ 0.7, 0 < c ≤ 0.5, 0 ≤ d ≤ 0.5, 0 ≤ e ≤ 0.2, 0 ≤ f ≤ 0.2, and 0 ≤ g ≤ 0.2. However, a + b1 + b2 + c + d + e + f + g ≤ 1.0.

[0184] The weight average molecular weight (Mw) of the polymer is preferably 1000 to 500000, more preferably 3000 to 100000. If Mw is within this range, sufficient etching resistance is obtained, and there is no risk of a decrease in resolution due to an inability to ensure a difference in dissolution rate before and after exposure. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or N,N-dimethylformamide (DMF) as a solvent.

[0185] Furthermore, since the influence of Mw / Mn on the molecular weight distribution of the polymer tends to increase 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 Mw / Mn is a narrow dispersion of 1.0 to 2.0. Within this range, there is little low or high molecular weight polymer, and there is no risk of foreign matter being found on the pattern or the shape of the pattern being deteriorated after exposure.

[0186] The polymer can be synthesized, for example, by polymerizing a monomer that provides the repeating unit described above in an organic solvent with the addition of a radical polymerization initiator by heating.

[0187] Specific 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). Specific 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 from 2 to 24 hours, and more preferably from 2 to 12 hours in terms of production efficiency.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] Specific examples of the base that can be used in the alkaline hydrolysis include aqueous ammonia, triethylamine, etc. 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.

[0192] 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.

[0193] Regarding the polymer obtained by the above-mentioned production method, a reaction solution obtained by a polymerization reaction may be used as the final product, or a powder obtained through a purification step such as a reprecipitation method in which a polymerization solution is added to a poor solvent to obtain a powder may be handled as the final product. However, from the viewpoint of work efficiency and quality stabilization, it is preferable to handle a polymer solution obtained by dissolving the powder obtained by the purification step in a solvent as the final product.

[0194] Specific examples of the solvent used in this case include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] to

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; 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 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, propylene glycol mono tert-butyl ether acetate, etc.; lactones such as GBL; alcohols such as diacetone alcohol (DAA); high-boiling alcohol solvents such as diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, etc.; and mixed solvents thereof.

[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 chemically amplified 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 in combination of multiple filters. 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] [Chemically amplified resist composition] [(A) Base polymer] The chemically amplified resist composition of the present invention contains as component (A) a base polymer which contains the above-mentioned polymer.

[0199] The polymers may be used alone or in combination of two or more with different composition ratios, Mw and / or Mw / Mn. The base polymer (A) may contain, in addition to the polymers, a hydrogenated ring-opening metathesis polymer, and the polymers described in JP-A-2003-66612 can be used.

[0200] [(B) Organic solvent] The chemically amplified resist composition of the present invention may contain an organic solvent as component (B). The organic solvent (B) is not particularly limited as long as it is capable of dissolving each of the components described above and below. Specific 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.

[0201] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, cyclohexanone, GBL, DAA, and mixed solvents thereof are preferred, as they have particularly excellent solubility for the base polymer of component (A).

[0202] In the chemically amplified resist composition of the present invention, the content of the organic solvent (B) is preferably 200 to 5000 parts by mass, and more preferably 400 to 3500 parts by mass, relative to 80 parts by mass of the base polymer (A). The organic solvent (B) may be used alone or in combination of two or more kinds.

[0203] [(C) Quencher] The chemically amplified resist composition of the present invention may contain a quencher as component (C). In the present invention, the 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.

[0204] Specific examples of the (C) quencher include onium salts represented by the following formula (1) or (2). [ka]

[0205] In formula (1), R q1 is 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. q2 is a hydrogen atom or a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom.

[0206] R q1 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; and aryl groups having 6 to 40 carbon atoms, such as phenyl group, naphthyl group and anthracenyl group. 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 -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.

[0207] R q2 Specific examples of the hydrocarbyl group represented by the formula: q1 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.

[0208] Specific examples of the anion of the onium salt represented by formula (1) include, but are not limited to, those shown below. [ka]

[0209] [ka]

[0210] [ka]

[0211] Specific examples of the anion of the onium salt represented by formula (2) include, but are not limited to, those shown below. [ka]

[0212] [ka]

[0213] [ka]

[0214] In formulas (1) and (2), 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]

[0215] 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 may be bonded to each other to form a ring together with the nitrogen atom to which they are bonded. Specific examples of the hydrocarbyl group include R ct1 ~R ct5 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0216] Specific examples of the ammonium cation represented by formula (cation-3) include, but are not limited to, those shown below. [ka]

[0217] Specific examples of the onium salt represented by formula (1) or (2) 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 the ion exchange reaction, refer to, for example, JP-A-2007-145797.

[0218] The onium salt represented by formula (1) or (2) 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 (1) or (2) 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.

[0219] In addition, as the quencher (C), an onium salt having a sulfonium cation and a phenoxide anion moiety in the same molecule as described in Japanese Patent No. 6,848,776, an onium salt having a sulfonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent No. 6,583,136 and JP-A-2020-200311, and an onium salt having an iodonium cation and a carboxylate anion moiety in the same molecule as described in Japanese Patent No. 6,274,755 can also be used.

[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 represented by formula (1) or (2) as the quencher (C), the content is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, relative to 80 parts by mass of the base polymer (A). If the onium salt type quencher of the component (C) is within the above range, the resolution is good and the sensitivity is not significantly reduced, which is preferable. The onium salt represented by formula (1) or (2) may be used alone or in combination of two or more kinds.

[0222] The chemically amplified resist composition of the present invention may contain a nitrogen-containing compound as a quencher (C). Specific examples of the nitrogen-containing compound of component (C) include primary, secondary, or tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond. In addition, compounds in which a primary or secondary amine is protected with a carbamate group, such as the compounds described in JP-A-3790649, may also be mentioned.

[0223] In addition, a sulfonium salt of sulfonic acid having a nitrogen-containing substituent may be used as the nitrogen-containing compound. Such a compound functions as a quencher in the unexposed area, and functions as a so-called photodegradable base in the exposed area, losing the quenching ability by neutralization with the acid generated by itself. By using a photodegradable base, the contrast between the exposed area and the unexposed area can be further enhanced. For example, JP-A-2009-109595 and JP-A-2012-46501 can be referred to for the photodegradable base.

[0224] When the chemically amplified resist composition of the present invention contains a nitrogen-containing compound as a quencher (C), the content thereof is preferably 0.001 to 12 parts by mass, more preferably 0.01 to 8 parts by mass, relative to 80 parts by mass of the base polymer (A). The nitrogen-containing compound may be used alone or in combination of two or more kinds.

[0225] [(D) Acid generator] The chemically amplified resist composition of the present invention may contain an acid generator within a range that does not impair the effects of the present invention. Examples of the acid generator include compounds (photoacid generators) that generate acid in response to actinic rays or radiation. The photoacid generator is not particularly limited as long as it is a compound that generates acid upon exposure to high-energy rays, but it is preferable that it generates sulfonic acid, imide acid, or methide acid. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate type acid generators. Specific examples of acid generators include those described in paragraphs

[0122] to

[0142] of JP-A-2008-111103.

[0226] In addition, as the photoacid generator, a sulfonium salt represented by the following formula (3-1) or an iodonium salt represented by the following formula (3-2) can also be suitably used. [ka]

[0227] In formulas (3-1) and (3-2), R 101 ~R 105 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. Specific examples of the halogen atom and hydrocarbyl group include R ct1 ~R ct5 Examples of the halogen atom and hydrocarbyl group represented by the formula (I) include the same as those exemplified above. 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, R may contain a hydroxyl group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro 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. 101 and R 102 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. Specific examples of the ring formed in this case are shown in the explanation of formula (cation-) as R ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, similar to those exemplified above.

[0228] Specific examples of the cation of the sulfonium salt represented by formula (3-1) include the same as those exemplified as the sulfonium cation represented by formula (cation-1). Specific examples of the cation of the iodonium salt represented by formula (4-2) include the same as those exemplified as the iodonium cation represented by formula (cation-2).

[0229] In formulas (3-1) and (3-2), Xa - is an anion selected from the following formulae (3A) to (3D). [ka]

[0230] In formula (3A), R fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the examples are similar to those given in the description of .

[0231] The anion represented by formula (3A) is preferably one represented by the following formula (3A'). [ka]

[0232] In formula (3A'), R HF is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group.

[0233] In formula (3A'), R fa1 is a hydrocarbyl group having 1 to 38 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. From the viewpoint of obtaining high resolution in the formation of a fine pattern, the hydrocarbyl group is preferably one having 6 to 30 carbon atoms.

[0234] R fa1 The hydrocarbyl group having 1 to 38 carbon atoms and represented by the formula (I) may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 38 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, and the like. Examples of the alkyl groups include cyclic saturated hydrocarbyl groups having 3 to 38 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 38 carbon atoms, such as an allyl group and a 3-cyclohexenyl group; aryl groups having 6 to 38 carbon atoms, such as a phenyl group, a 1-naphthyl group, and a 2-naphthyl group; aralkyl groups having 7 to 38 carbon atoms, such as a benzyl group and a diphenylmethyl group; and groups obtained by combining these.

[0235] 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 the - 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, or the like. The heteroatom is preferably an oxygen atom. Specific 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.

[0236] Synthesis of sulfonium salts containing an anion represented by formula (3A') is described in detail in JP-A-2007-145797, JP-A-2008-106045, JP-A-2009-7327, JP-A-2009-258695, etc. In addition, sulfonium salts described in JP-A-2010-215608, JP-A-2012-41320, JP-A-2012-106986, JP-A-2012-153644, etc. are also preferably used.

[0237] Specific examples of the anion represented by formula (3A) include, but are not limited to, those shown below: In the following formula, Ac is an acetyl group. [ka]

[0238] [ka]

[0239] [ka]

[0240] [ka]

[0241] In formula (3B), R fb1 and R fb2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 means that the groups to which they are bonded (-CF 2 -SO 2 -N - -SO 2 -CF 2 -) together to form a ring, in which case, R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0242] In formula (3C), R fc1 , R fc2 and R fc3 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fc1 , R fc2and R fc3 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 means that the groups to which they are bonded (-CF 2 -SO 2 -C - -SO 2 -CF 2 -) together to form a ring, in which case, R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0243] In formula (3D), R fd is a hydrocarbyl group having 1 to 40 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 fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0244] The synthesis of a sulfonium salt containing an anion represented by formula (3D) is described in detail in JP-A-2010-215608 and JP-A-2014-133723.

[0245] Specific examples of the anion represented by formula (3D) include, but are not limited to, those shown below. [ka]

[0246] [ka]

[0247] Although the photoacid generator containing the anion represented by formula (3D) does not have a fluorine atom at the α-position of the sulfo group, it has two trifluoromethyl groups at the β-position, and therefore has sufficient acidity to cleave the acid labile group in the base polymer, and can therefore be used as a photoacid generator.

[0248] As the photoacid generator, a compound represented by the following formula (4) can also be suitably used. [ka]

[0249] In formula (4), R 201 and R 202 R is each independently a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. 203 is a hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom. 201 , R 202 and R 203 Any two of 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 R ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, similar to those exemplified above.

[0250] R 201 and R 202The hydrocarbyl group having 1 to 30 carbon atoms and represented by the formula (I) 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, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group or 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, an oxanorbornyl group, a tricyclo[5.2.1.0 2,6 ] decyl group, adamantyl group, and other cyclic saturated hydrocarbyl groups having 3 to 30 carbon atoms; phenyl group, methylphenyl group, ethylphenyl group, n-propylphenyl group, isopropylphenyl group, n-butylphenyl group, isobutylphenyl group, sec-butylphenyl group, tert-butylphenyl group, naphthyl group, methylnaphthyl group, ethylnaphthyl group, n-propylnaphthyl group, isopropylnaphthyl group, n-butylnaphthyl group, isobutylnaphthyl group, sec-butylnaphthyl group, tert-butylnaphthyl group, anthracenyl group, and other aryl groups having 6 to 30 carbon atoms; and groups obtained by combining these. 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 cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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.

[0251] R 203The hydrocarbylene group having 1 to 30 carbon atoms represented by the following formula may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkanediyl groups having 1 to 30 carbon atoms, such as a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, a dodecane-1,12-diyl group, a tridecane-1,13-diyl group, a tetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, a hexadecane-1,16-diyl group, and a heptadecane-1,17-diyl group; a cyclopentanediyl group, a cyclohexanediyl group, and the like. cyclic saturated hydrocarbylene groups having 3 to 30 carbon atoms, such as xanediyl group, norbornanediyl group, and adamantanediyl group; arylene groups having 6 to 30 carbon atoms, such as phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, and tert-butylnaphthylene group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbylene 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 heteroatom may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, 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. As the heteroatom, an oxygen atom is preferable.

[0252] In formula (4), L A is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a single bond, an ether bond, or a heteroatom. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples of the hydrocarbylene group include: 203 Examples of the hydrocarbylene group represented by the formula (I) include the same as those exemplified above.

[0253] In formula (4), X A , X B , X C and X D are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group. A , X B , X C and X D At least one of the groups is a fluorine atom or a trifluoromethyl group.

[0254] In formula (4), k is an integer of 0 to 3.

[0255] The photoacid generator represented by formula (4) is preferably one represented by the following formula (4'). [ka]

[0256] In formula (4'), L A is the same as above. R HF R is a hydrogen atom or a trifluoromethyl group, preferably a trifluoromethyl group. 301 , R 302 and R 303 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 R fa1 Examples of the hydrocarbyl group represented by the formula: are the same as those exemplified above. Each of x and y is independently an integer of 0 to 5. z is an integer of 0 to 4.

[0257] Specific examples of the photoacid generator represented by formula (4) include the same as those exemplified as the photoacid generator represented by formula (2) in JP2017-26980A.

[0258] Among the photoacid generators, those containing an anion represented by formula (3A') or (3D) are particularly preferred because of their small acid diffusion and excellent solubility in solvents. Also, those represented by formula (4') are particularly preferred because of their extremely small acid diffusion.

[0259] As other acid generators, sulfonium salts and iodonium salts containing an anion having an aromatic ring substituted with an iodine atom, represented by the following formula (5-1) or (5-2), can also be used. [ka]

[0260] In formulae (5-1) and (5-2), p is 1, 2, or 3. q and r are integers satisfying 1≦q≦5, 0≦r≦3, and 1≦q+r≦5. q is preferably 1, 2, or 3, and more preferably 2 or 3. r is preferably 0, 1, or 2.

[0261] In formulas (5-1) and (5-2), L 1 is a single bond, an ether bond or an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched or cyclic.

[0262] In formulas (5-1) and (5-2), L 2 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when p is 1, and represents a (p+1)-valent linking group having 1 to 20 carbon atoms when p is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0263] In formulas (5-1) and (5-2), R 401is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms or a hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond, or 401A )(R 401B ), -N(R 401C )-C(=O)-R 401D Or -N(R 401C )-C(=O)-OR 401D R 401A and R 401B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 401C R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. 401D is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 14 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When p and / or r is 2 or more, each R 401 may be the same or different from each other.

[0264] Of these, R 401Examples of the hydroxyl group include -N(R 401C )-C(=O)-R 401D , -N(R 401C )-C(=O)-OR 401D , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, and the like are preferred.

[0265] In formulas (5-1) and (5-2), Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, at least one of which is a fluorine atom or a trifluoromethyl group. 11 and Rf 12 may combine to form a carbonyl group. 13 and Rf 14 are preferably both fluorine atoms.

[0266] In formulas (5-1) and (5-2), R 402 ~R 406 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R ct1 ~R ct5 In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, a cyano group, a nitro group, a mercapto group, a sultone ring, a sulfo group or a sulfonium salt-containing group, and the -CH 2 A part of R may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond or a sulfonate bond. 402 and R 403 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 R ct1 and R ct2may be bonded to each other to form a ring together with the sulfur atom to which they are bonded, similar to those exemplified above.

[0267] Specific examples of the cation of the sulfonium salt represented by formula (5-1) include the same as those exemplified as the sulfonium cation represented by formula (cation-1). Specific examples of the cation of the iodonium salt represented by formula (5-2) include the same as those exemplified as the iodonium cation represented by formula (cation-2).

[0268] Specific examples of the anion of the onium salt represented by formula (5-1) or (5-2) include, but are not limited to, those shown below. [ka]

[0269] [ka]

[0270] [ka]

[0271] [ka]

[0272] [ka]

[0273] [ka]

[0274] [ka]

[0275]

change

[0276]

change

[0277]

change

[0278]

change

[0279]

change

[0280]

change

[0281]

change

[0282]

change

[0283]

change

[0284]

change

[0285]

change

[0286] [ka]

[0287] [ka]

[0288] [ka]

[0289] [ka]

[0290] When the chemically amplified resist composition of the present invention contains an acid generator (D), the content is preferably 0.1 to 40 parts by mass, more preferably 0.5 to 20 parts by mass, relative to 80 parts by mass of the base polymer (A). If the amount of the acid generator (D) added is within the above range, the resolution is good and there is no risk of problems with foreign matter occurring after development of the resist film or during stripping, which is preferable. The acid generator (D) may be used alone or in combination of two or more types.

[0291] [(E) Surfactant] The chemically amplified resist composition of the present invention may further contain a surfactant as component (E). The surfactant (E) is preferably a surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer, or a surfactant that is insoluble or poorly soluble in water and an alkaline developer. Examples of such surfactants include those described in JP-A-2010-215608 and JP-A-2011-16746.

[0292] Among the surfactants described in the above publication, preferred surfactants that are insoluble or poorly soluble in water and alkaline developers include FC-4430 (manufactured by 3M), Surflon (registered trademark) S-381 (manufactured by AGC Seimi Chemical Co., Ltd.), Olfine (registered trademark) E1004 (manufactured by Nissin Chemical Industry Co., Ltd.), KH-20, KH-30 (manufactured by AGC Seimi Chemical Co., Ltd.), and an oxetane ring-opening polymer represented by the following formula (surf-1): [ka]

[0293] Here, R, Rf, A, B, C, m, and n apply only to formula (surf-1), regardless of the above description. R is a divalent to tetravalent aliphatic group having 2 to 5 carbon atoms. Examples of the aliphatic group include divalent ones such as ethylene group, 1,4-butylene group, 1,2-propylene group, 2,2-dimethyl-1,3-propylene group, and 1,5-pentylene group, and examples of trivalent or tetravalent ones include the following: [ka] (In the formula, the dashed lines represent bonds and are partial structures derived from glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol, respectively.)

[0294] Among these, a 1,4-butylene group, a 2,2-dimethyl-1,3-propylene group, and the like are preferable.

[0295] Rf is a trifluoromethyl group or a pentafluoroethyl group, preferably a trifluoromethyl group. m is an integer of 0 to 3, n is an integer of 1 to 4, and the sum of n and m is the valence of R, which is an integer of 2 to 4. A is 1. B is an integer of 2 to 25, preferably an integer of 4 to 20. C is an integer of 0 to 10, preferably 0 or 1. The order of the constituent units in the formula (surf-1) is not specified, and they may be bonded in blocks or randomly. The production of a partially fluorinated oxetane ring-opening polymer surfactant is described in detail in the specification of U.S. Pat. No. 5,650,483.

[0296] A surfactant that is insoluble or poorly soluble in water and soluble in an alkaline developer has a function of reducing water penetration and leaching by orienting on the surface of the resist film when a resist protective film is not used in ArF immersion lithography. Therefore, it is useful for suppressing the elution of water-soluble components from the resist film and reducing damage to the exposure device, and is also useful because it is soluble during development with an alkaline aqueous solution after exposure or post-exposure bake (PEB) and is unlikely to become a foreign matter that causes defects. Such surfactants are insoluble or poorly soluble in water and soluble in an alkaline developer, and are polymer-type surfactants, also called hydrophobic resins, and are particularly preferred for their high water repellency and improved water slippage.

[0297] Specific examples of such polymeric surfactants include those containing at least one type selected from the repeating units represented by the following formulas (6A) to (6E). [ka]

[0298] In formulas (6A) to (6E), R B is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 Ha-CH 2 -, -CH 2 CH 2 -, -O- or two -H separated from each other.s1 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 10 carbon atoms. s2 R is a single bond or a linear or branched hydrocarbylene group having 1 to 5 carbon atoms. s3 R are each independently a hydrogen atom, a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group. s3 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. s4 is a (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group having 1 to 20 carbon atoms. u is an integer of 1 to 3. s5 each independently represents a hydrogen atom or -C(=O)-OR sa R is a group represented by the formula: sa R is a fluorinated hydrocarbyl group having 1 to 20 carbon atoms. s6 is a hydrocarbyl group or a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, and an ether bond or a carbonyl group may be present between the carbon-carbon bonds.

[0299] R s1 The hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) is preferably a saturated hydrocarbyl group, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornyl. Of these, those having 1 to 6 carbon atoms are preferred.

[0300] R s2The hydrocarbylene group represented by the formula (I) is preferably a saturated hydrocarbylene group, which may be linear, branched or cyclic. Specific examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group and a pentylene group.

[0301] R s3 or R s6 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbyl groups, and aliphatic unsaturated hydrocarbyl groups such as alkenyl groups and alkynyl groups, with saturated hydrocarbyl groups being preferred. Specific examples of the saturated hydrocarbyl group include R s1 In addition to the examples of the hydrocarbyl group represented by the formula (I), examples thereof include an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, and a pentadecyl group. s3 or R s6 Specific examples of the fluorinated hydrocarbyl group represented by the formula (1) include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the aforementioned hydrocarbyl group have been replaced with fluorine atoms. As described above, an ether bond or a carbonyl group may be present between these carbon-carbon bonds.

[0302] R s3 Specific examples of the acid labile group represented by the formula (AL-3) to (AL-5) include the groups represented by the formulas (AL-3) to (AL-5) above, trialkylsilyl groups in which each alkyl group has 1 to 6 carbon atoms, and oxo group-containing alkyl groups having 4 to 20 carbon atoms.

[0303] R s4 The (u+1)-valent hydrocarbon group or fluorinated hydrocarbon group represented by the formula (1) may be linear, branched, or cyclic, and specific examples thereof include groups obtained by further eliminating u hydrogen atoms from the above-mentioned hydrocarbyl group or fluorinated hydrocarbyl group.

[0304] R saThe fluorinated hydrocarbyl group represented by the formula (I) is preferably saturated and may be linear, branched or cyclic. Specific examples thereof include those in which some or all of the hydrogen atoms of the hydrocarbyl groups have been substituted with fluorine atoms. Specific examples thereof include a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a 3,3,3-trifluoro-1-propyl group, a 3,3,3-trifluoro-2-propyl group, a 2,2,3,3-tetrafluoropropyl group, a 1,1,1,3,3,3-hexafluoroisopropyl group, a 2,2,3,3,4,4,4-heptafluorobutyl group, a 2,2,3,3,4,4,5,5-octafluoropentyl group, a 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl group, a 2-(perfluorobutyl)ethyl group, a 2-(perfluorohexyl)ethyl group, a 2-(perfluorooctyl)ethyl group, and a 2-(perfluorodecyl)ethyl group.

[0305] Specific examples of the repeating unit represented by any one of formulas (6A) to (6E) include, but are not limited to, those shown below. B is the same as above. [ka]

[0306] [ka]

[0307] [ka]

[0308] [ka]

[0309] [ka]

[0310] The polymer surfactant may further contain other repeating units than the repeating units represented by formulae (6A) to (6E). Specific examples of the other repeating units include repeating units obtained from methacrylic acid and α-trifluoromethylacrylic acid derivatives. In the polymer surfactant, the content of the repeating units represented by formulae (6A) to (6E) in the total repeating units is preferably 20 mol % or more, more preferably 60 mol % or more, and even more preferably 100 mol %.

[0311] The Mw of the polymer surfactant is preferably from 1,000 to 500,000, and more preferably from 3,000 to 100,000. The Mw / Mn is preferably from 1.0 to 2.0, and more preferably from 1.0 to 1.6.

[0312] The method for synthesizing the polymeric surfactant includes a method in which a monomer containing an unsaturated bond that gives the repeating units represented by formulae (6A) to (6E) and other repeating units as necessary is heated in an organic solvent with the addition of a radical initiator to polymerize. Specific examples of the organic solvent used during polymerization include toluene, benzene, THF, diethyl ether, and dioxane. Specific examples of the polymerization initiator include AIBN, 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. The reaction temperature is preferably 50 to 100°C. The reaction time is preferably 4 to 24 hours. The acid labile group introduced into the monomer may be used as it is, or may be protected or partially protected after polymerization.

[0313] When synthesizing the polymeric surfactant, a known chain transfer agent such as dodecyl mercaptan or 2-mercaptoethanol may be used to adjust the molecular weight. In this case, the amount of the chain transfer agent added is preferably 0.01 to 10 mol% based on the total moles of the monomers to be polymerized.

[0314] When the chemically amplified resist composition of the present invention contains a surfactant (E), the content is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 10 parts by mass, relative to 80 parts by mass of the base polymer (A). If the surfactant (E) content is 0.1 part by mass or more, the receding contact angle between the resist film surface and water is sufficiently improved, and if it is 50 parts by mass or less, the dissolution rate of the resist film surface in the developer is low, and the height of the formed fine pattern is sufficiently maintained. The surfactant (E) may be used alone or in combination of two or more kinds.

[0315] [(F) Dissolution inhibitor] The chemically amplified resist composition of the present invention may further contain a dissolution inhibitor as component (F). When the chemically amplified resist composition of the present invention is a positive type, the difference in dissolution rate between exposed and unexposed areas can be further increased by blending a dissolution inhibitor, thereby further improving resolution.

[0316] Specific examples of the dissolution inhibitor include a compound having a molecular weight of preferably 100 to 1000, more preferably 150 to 800, and containing two or more phenolic hydroxyl groups in the molecule, in which the hydrogen atoms of the phenolic hydroxyl groups are substituted with acid labile groups at a ratio of 0 to 100 mol % as a whole, or a compound having a carboxyl group in the molecule, in which the hydrogen atoms of the carboxyl groups are substituted with acid labile groups at an average ratio of 50 to 100 mol % as a whole.Specific examples include compounds in which the hydrogen atoms of the hydroxyl groups and carboxyl groups of bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalene carboxylic acid, adamantane carboxylic acid, and cholic acid are substituted with acid labile groups, and the like, for example, those described in paragraphs

[0155] to

[0178] of JP2008-122932A.

[0317] When the chemically amplified resist composition of the present invention contains the dissolution inhibitor (F), the content thereof is preferably from 0 to 50 parts by mass, and more preferably from 5 to 40 parts by mass, per 80 parts by mass of the base polymer (A).

[0318] [(G) Other ingredients] The chemically amplified resist composition of the present invention may contain, as (G) other components, a compound that decomposes with an acid to generate an acid (acid amplifying compound), an organic acid derivative, a fluorine-substituted alcohol, a water repellency improver, etc. As the acid amplifying compound, the compounds described in JP-A-2009-269953 or JP-A-2010-215608 can be referred to. When the acid amplifying compound is contained, the content is preferably 0 to 5 parts by mass, more preferably 0 to 3 parts by mass, relative to 80 parts by mass of the (A) base polymer. If the content is too high, it is difficult to control acid diffusion, and degradation of resolution and pattern shape may occur. As the organic acid derivative and fluorine-substituted alcohol, the compounds described in JP-A-2009-269953 or JP-A-2010-215608 can be referred to.

[0319] The water repellency improver can be used in immersion lithography without using a topcoat. As the water repellency improver, a polymer containing a fluorinated alkyl group, a polymer containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue of a specific structure, etc. are preferred, and those exemplified in JP-A-2007-297590, JP-A-2008-111103, etc. are more preferred. The water repellency improver needs to be dissolved in an alkaline developer or an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, a polymer containing a repeating unit containing an amino group or an amine salt is highly effective in preventing the evaporation of the acid in the PEB and preventing the opening failure of the hole pattern after development. When the chemically amplified resist composition of the present invention contains the water repellency improver, the content thereof is preferably from 0 to 20 parts by mass, and more preferably from 0.5 to 10 parts by mass, per 80 parts by mass of the (A) base polymer.

[0320] [Pattern formation method] When the chemically amplified resist composition of the present invention is used in various integrated circuit manufacturing processes, known lithography techniques can be applied. For example, a pattern forming method includes a process of forming a resist film on a substrate using the above-mentioned chemically amplified resist composition, a process of exposing the resist film to high-energy radiation, and a process of developing the exposed resist film using a developer.

[0321] First, the chemically amplified resist composition of the present invention is applied to a substrate (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 The resist is applied onto a substrate (e.g., a substrate) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., so that the coating thickness is 0.01 to 2.0 μm. This is then pre-baked on a hot plate, preferably at 60 to 150° C. for 10 seconds to 30 minutes, more preferably at 80 to 120° C. for 30 seconds to 20 minutes, to form a resist film.

[0322] Next, the resist film is exposed to high-energy radiation. Examples of the high-energy radiation include ultraviolet radiation, far ultraviolet radiation, EB, EUV radiation with a wavelength of 3 to 15 nm, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, etc. When ultraviolet radiation, far ultraviolet radiation, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, etc. are used as the high-energy radiation, the exposure dose is preferably 1 to 200 mJ / cm2, either directly or using a mask for forming a desired pattern. 2 Approximately, more preferably 10 to 100 mJ / cm 2 When EB is used as the high energy beam, the exposure dose is preferably 0.1 to 100 μC / cm 2 Approximately, more preferably 0.5 to 50 μC / cm 2The chemically amplified resist composition of the present invention is particularly suitable for fine patterning using high energy rays such as ArF excimer laser light with a wavelength of 193 nm, KrF excimer laser light with a wavelength of 248 nm, EB, or EUV with a wavelength of 3 to 15 nm, X-rays, soft X-rays, γ-rays, or synchrotron radiation.

[0323] After the exposure, PEB may be performed on a hot plate, preferably at 60 to 150° C. for 10 seconds to 30 minutes, more preferably at 80 to 120° C. for 30 seconds to 20 minutes.

[0324] After exposure or PEB, development is performed using a developer of an alkaline aqueous solution of 0.1 to 10 mass %, preferably 2 to 5 mass %, of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, or the like for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, by a conventional method such as a dip method, a puddle method, a spray method, or the like. The portions irradiated with light are dissolved in the developer, while the portions not exposed to light are not dissolved, and the desired positive pattern is formed on the substrate.

[0325] A negative pattern can also be obtained by using an organic solvent developer instead of the alkaline aqueous solution. Specific examples of the developer used in this case include 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, butenyl acetate, isopentyl acetate, propyl formate, butyl formate, isobutyl formate, pentyl formate, isopentyl formate, methyl valerate, methyl pentenoate, methyl crotonate, and ethyl crotonate. Examples of the organic solvent include methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, pentyl lactate, isopentyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate, 2-phenylethyl acetate, etc. These organic solvents may be used alone or in combination of two or more.

[0326] At the end of the development, rinsing may be performed. As the rinsing liquid, a solvent that is miscible with the developer and does not dissolve the resist film is preferable. As such a solvent, alcohols having 3 to 10 carbon atoms, ether compounds having 8 to 12 carbon atoms, alkanes, alkenes, alkynes, and aromatic solvents having 6 to 12 carbon atoms are preferably used.

[0327] Specific examples of the alcohol having 3 to 10 carbon atoms include n-propyl alcohol, isopropyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-pentyl alcohol, neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, and 3-hexanol. Examples of such an alcohol include 2,3-dimethyl-2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, and 1-octanol.

[0328] Specific examples of the ether compound having 8 to 12 carbon atoms include di-n-butyl ether, diisobutyl ether, di-sec-butyl ether, di-n-pentyl ether, diisopentyl ether, di-sec-pentyl ether, di-tert-pentyl ether, and di-n-hexyl ether.

[0329] Specific examples of the alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Specific examples of the alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Specific examples of the alkynes having 6 to 12 carbon atoms include hexine, heptine, octyne, etc.

[0330] Specific examples of the aromatic solvent include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0331] Rinsing can reduce the occurrence of resist pattern collapse and defects. Rinsing is not always necessary, and not performing rinsing can reduce the amount of solvent used.

[0332] The developed hole pattern or trench pattern can also be shrunk by thermal flow, RELACS technology, or DSA technology. A shrink agent is applied onto the hole pattern, and the shrink agent crosslinks on the surface of the resist film due to the diffusion of an acid catalyst from the resist film during baking, and the shrink agent adheres to the sidewalls of the hole pattern. The baking temperature is preferably 70 to 180°C, more preferably 80 to 170°C, and the baking time is preferably 10 to 300 seconds, and excess shrink agent is removed to reduce the hole pattern. EXAMPLES

[0333] 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. The apparatuses used are as follows. MALDI TOF-MS: JEOL S3000

[0334] [1] Synthesis of onium salt monomers [Example 1-1] Synthesis of onium salt type monomer a-1 [ka]

[0335] (1) Synthesis of intermediate In-1 In a nitrogen atmosphere, raw materials SM-1 (37.2 g), triethylamine (18.0 g) and 4-dimethylaminopyridine (1.50 g) were dissolved or suspended in THF (200 g) in a reaction vessel and cooled in an ice bath. Then, a solution of p-styrenesulfonyl chloride (16.4 g) dissolved in THF (50 g) was added dropwise. After the dropwise addition, the temperature in the reaction vessel was raised to 50°C and aged for 6 hours. Then, the reaction solution was cooled and saturated sodium bicarbonate water (100 g) was added to stop the reaction. The target product was extracted twice with ethyl acetate (200 g), and the usual aqueous work-up was performed. After the solvent was distilled off, the intermediate In-1 was obtained as an oily product in an amount of 45.8 g (yield 97%) by purifying it by silica gel chromatography.

[0336] (2) Synthesis of intermediate In-2 Under a nitrogen atmosphere, intermediate In-1 (45.8 g) was dissolved in THF (200 g). While cooling in an ice bath, 25% by mass aqueous sodium hydroxide solution (15.5 g) was added dropwise. After the addition, the temperature in the reaction vessel was raised to 30°C and aged for 12 hours. After aging, the reaction solution was cooled and 20% by mass hydrochloric acid (18.2 g) was added dropwise to stop the reaction. The target product was extracted twice with ethyl acetate (200 g), and after normal aqueous work-up, the solvent was distilled off, and recrystallization was performed with hexane to obtain 37.5 g of intermediate In-2 as white crystals (yield 90%).

[0337] (3) Synthesis of intermediate In-3 Under a nitrogen atmosphere, intermediate In-2 (37.5 g), raw material SM-2 (34.8 g), 4-dimethylaminopyridine (1.1 g) and methylene chloride (150 g) were added to a reaction vessel and cooled in an ice bath. While maintaining the temperature in the reaction vessel at 20°C or less, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (20.1 g) was added as a powder. After the addition, the temperature was raised to room temperature and aged for 12 hours. After aging, water (100 g) was added to stop the reaction, and the reaction was subjected to a normal aqueous work-up. After the solvent was distilled off, diisopropyl ether was added to recrystallize, and 61.5 g of intermediate In-3 was obtained as an oil (yield 89%).

[0338] (4) Synthesis of onium salt monomer a-1 Under a nitrogen atmosphere, intermediate In-3 (61.5 g), raw material SM-3 (31.8 g), methylene chloride (200 g) and water (150 g) were added to a reaction vessel, stirred for 30 minutes, and then the organic layer was separated, washed with water, and then concentrated under reduced pressure. The concentrated liquid was purified by silica gel chromatography to obtain 61.0 g of the target onium salt monomer a-1 as an oily product (yield 87%). MALDI TOF-MS: POSITIVE M + 261(C 18 H 13 S + equivalent) NEGATIVE M - 766(C 18 H 10 F 5 I 2 O 8 S 2 - equivalent)

[0339] [Examples 1-2 to 1-7] Synthesis of onium salt monomers a-2 to a-10 Using the corresponding raw materials and known organic synthesis reactions, onium salt monomers a-2 to a-10 represented by the following formulas were synthesized. [ka]

[0340] [ka]

[0341] [Comparative Examples 1-1 to 1-4] Synthesis of Comparative Onium Salt Monomers ca-1 to ca-4 Using the corresponding raw materials and known organic synthesis reactions, comparative onium salt monomers ca-1 to ca-4 represented by the following formulas were synthesized. [ka]

[0342] [2] Synthesis of base polymer Among the monomers used in the synthesis of the base polymer, those other than the monomers a-1 to a-10 and the comparative monomers ca-1 to ca-4 are as follows. [ka]

[0343] [ka]

[0344] [ka]

[0345] [Example 2-1] Synthesis of polymer P-1 In a nitrogen atmosphere, monomer a-1 (49.4 g), monomer b1-1 (39.3 g), monomer c-1 (11.5 g), 3.68 g of V-601 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 139 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 the mixture was stirred for 2 hours, and then cooled to room temperature. The obtained polymerization liquid was dropped into 3000 g of vigorously stirred hexane, and the precipitated polymer was filtered off. 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 97.1 g, yield 97%). Polymer P-1 had an Mw of 9400 and an Mw / Mn of 1.75. Note that Mw was a value measured in terms of polystyrene by GPC using DMF as a solvent. [ka]

[0346] [Examples 2-2 to 2-23, Comparative Examples 2-1 to 2-10] Synthesis of Polymers P-2 to P-23 and Comparative Polymers CP-1 to CP-10 The polymers shown in Tables 1 and 2 were produced in the same manner as in Synthesis Example 2-1, except that the types and compounding ratios of the respective monomers were changed.

[0347] [Table 1]

[0348] [Table 2]

[0349] [3] Preparation of chemically amplified resist composition [Examples 3-1 to 3-26, Comparative Examples 3-1 to 3-10] Predetermined components selected from the base polymers of the present invention (P-1 to P-23), comparative base polymers (CP-1 to CP-10), acid generators (PAG-1, PAG-2) and quenchers (SQ-1 to SQ-3, AQ-1) were dissolved in a solvent containing 0.01 mass % of FC-4430 manufactured by 3M as a surfactant in the compositions shown in Tables 3 and 4 below, and the solutions were filtered through a 0.2 μm Teflon (registered trademark) type filter to prepare chemically amplified resist compositions (R-1 to R-26, CR-1 to CR-10).

[0350] [Table 3]

[0351] [Table 4]

[0352] In Tables 3 and 4, the solvents, quenchers (SQ-1 to SQ-4, AQ-1) and acid generators (PAG-1, PAG-2) are as follows. Solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (Diacetone Alcohol)

[0353] Quencher: SQ-1~SQ-4, AQ-1 [ka]

[0354] Acid generator: PAG-1, PAG-2 [ka]

[0355] [4] EUV Lithography Evaluation (1) [Examples 4-1 to 4-26, Comparative Examples 4-1 to 4-10] Each chemically amplified resist composition (R-1 to R-26, CR-1 to CR-10) shown in Tables 3 and 4 was spin-coated onto a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) manufactured by Shin-Etsu Chemical Co., Ltd. had been formed to a thickness of 20 nm, and the substrate was pre-baked at 100°C for 60 seconds using a hot plate to produce a resist film with a thickness of 50 nm. The resist film was exposed to an LS pattern with an on-wafer dimension of 18 nm and a pitch of 36 nm using an ASML EUV scanner NXE3300 (NA 0.33, σ 0.9 / 0.6, dipole illumination) with varying exposure dose and focus (exposure dose pitch: 1 mJ / cm 2 After exposure, PEB was performed for 60 seconds at the temperatures shown in Tables 5 and 6. Thereafter, paddle development was performed with a 2.38 mass % TMAH aqueous solution for 30 seconds, followed by rinsing with a surfactant-containing rinse material and spin drying to obtain a positive pattern. The obtained LS pattern was observed with a critical dimension SEM (CG6300) manufactured by Hitachi High-Technologies Corporation, and the sensitivity, EL, LWR, DOF and collapse limit were evaluated according to the following methods. The results are shown in Tables 5 and 6.

[0356] [Sensitivity evaluation] The optimal exposure dose Eop (mJ / cm) to obtain an LS pattern with a line width of 18 nm and a pitch of 36 nm2 ) was calculated and used as the sensitivity. The smaller this value, the higher the sensitivity.

[0357] [EL Rating] From the exposure amount formed within the range of ±10% (16.2 to 19.8 nm) of the 18 nm space width in the LS pattern, EL (unit: %) was calculated by the following formula. The larger this value, the better the performance. EL(%)=(|E 1 -E 2 | / Eop)×100 E 1 : Optimal exposure dose for LS pattern with line width of 16.2 nm and pitch of 36 nm E 2 : Optimal exposure dose to give LS pattern with line width of 19.8 nm and pitch of 36 nm Eop: Optimal exposure dose for LS pattern with line width of 18 nm and pitch of 36 nm

[0358] [LWR rating] The LS pattern obtained by irradiating at Eop was measured at 10 points along the line length, and the LWR was calculated as three times the standard deviation (σ). The smaller this value, the smaller the roughness and the more uniform the line width of the pattern.

[0359] [DOF evaluation] For the evaluation of the depth of focus, the focus range formed within the range of ±10% (16.2 to 19.8 nm) of the dimension of 18 nm in the LS pattern was obtained. The larger this value, the wider the depth of focus.

[0360] [Line pattern collapse limit evaluation] The line dimension of each exposure dose at the optimum focus of the LS pattern was measured at 10 points in the longitudinal direction. The thinnest line dimension obtained without collapse was defined as the collapse limit dimension. The smaller this value, the better the collapse limit.

[0361] [Table 5]

[0362] [Table 6]

[0363] From the results shown in Tables 5 and 6, it was found that the chemically amplified resist composition using the base polymer containing the repeating unit derived from the onium salt type monomer of the present invention has good sensitivity and is excellent in EL, LWR and DOF. In addition, it was confirmed that the collapse limit value is small and the pattern is resistant to collapse even in fine pattern formation. Therefore, it was shown that the chemically amplified resist composition of the present invention is suitable as a material for EUV lithography.

[0364] [5] EUV Lithography Evaluation (2) [Examples 5-1 to 5-26, Comparative Examples 5-1 to 5-10] Each chemically amplified resist composition (R-1 to R-26, CR-1 to CR-10) shown in Tables 3 and 4 was spin-coated on a Si substrate on which a silicon-containing spin-on hard mask SHB-A940 (silicon content 43% by mass) made by Shin-Etsu Chemical Co., Ltd. was formed to a thickness of 20 nm, and the resist film was pre-baked for 60 seconds at 105°C using a hot plate to produce a resist film with a thickness of 50 nm. This was exposed using an EUV scanner NXE3400 (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, a hole pattern mask with a pitch of 46 nm on the wafer and a +20% bias), and PEB was performed for 60 seconds using a hot plate at the temperatures shown in Tables 7 and 8, and development was performed for 30 seconds with a 2.38% by mass TMAH aqueous solution to form a hole pattern with a dimension of 23 nm. Using a Hitachi High-Technologies Corporation CD-SEM (CG6300), the exposure dose when the hole dimension was 23 nm was measured and used as the sensitivity. The dimensions of 50 holes were also measured, and the standard deviation (σ) calculated from the results was tripled (3σ) to use as the dimensional variation (CDU). The results are shown in Tables 7 and 8.

[0365] [Table 7]

[0366] [Table 8]

[0367] The results shown in Tables 7 and 8 confirm that the chemically amplified resist composition of the present invention has good sensitivity and excellent CDU.

[0368] [6] Dry etching resistance evaluation [Examples 6-1 to 6-23, Comparative Examples 6-1 to 6-10] 2 g of each of the polymers shown in Tables 1 and 2 (polymers P-1 to P-23, comparative polymers CP-1 to CP-10) was dissolved in 10 g of cyclohexanone and filtered through a 0.2 μm filter to form a polymer solution on a Si substrate by spin coating to form a film with a thickness of 300 nm. The film was then evaluated under the following conditions. CHF 3 / CF 4 Etching test with fluorine-based gas: The difference in thickness of the polymer film before and after etching was determined using a dry etching apparatus TE-8500P manufactured by Tokyo Electron Limited. The etching conditions are as follows: Chamber pressure 40Pa RF power 1000W Gap 9mm CHF 3 Gas flow rate: 30mL / min CF 4 Gas flow rate: 30mL / min Ar gas flow rate: 100mL / min Time 60sec In this evaluation, a film with a smaller difference in film thickness, that is, a smaller amount of reduction, indicates high etching resistance. The dry etching resistance results are shown in Tables 9 and 10.

[0369] [Table 9]

[0370] [Table 10]

[0371] From the results shown in Tables 9 and 10, the polymer of the present invention has 3 / CF 4 It was confirmed that the material had excellent dry etching resistance against SiO2-based gases.

Claims

1. An onium salt monomer represented by the following formula (a): 【Chemistry 1】 (In the formula, n1 is 0 or 1. n2 is 0 or 1. n3 is an integer from 0 to 4. n4 is an integer from 0 to 4. n5 is an integer from 1 to 6. However, when n2 is 0, 1≦n4+n5≦4, and when n2 is 1, 1≦n4+n5≦6. n6 is an integer from 0 to 4. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. When n3 is 2, 3, or 4, a plurality of R 1 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom other than an iodine atom or a heteroatom. 2 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. L A , L B and L C are each independently a single bond, an ether bond, an ester bond, a sulfonate ester bond, a sulfonate amide bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. Q 1 and Q. 2 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Q 3 and Q. 4 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Z + is an onium cation.

2. The onium salt monomer according to claim 1, which is represented by the following formula (a1): 【Chemistry 2】 (In the formula, n1 to n6, R A , R 1 , R 2 , L A , L C , Q 1 ~Q 4 and Z + is the same as above.)

3. The onium salt monomer according to claim 2, which is represented by the following formula (a2): 【Chemistry 3】 (In the formula, n1 to n6, R A , R 1 , R 2 , L A , Q 1 , Q 2 and Z + is the same as above.)

4. Z + The onium salt monomer according to claim 1, wherein is a sulfonium cation represented by the following formula (category-1) or an iodonium cation represented by the following formula (category-2). 【Chemistry 4】 (In the formula, R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom. ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

5. A polymer comprising a repeating unit derived from the onium salt type monomer according to any one of claims 1 to 4.

6. The polymer according to claim 5 , further comprising a repeating unit represented by the following formula (b1) or (b2): 【Chemistry 5】 (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, a phenylene group, a naphthylene group, *-C(=O)-O-X 11 - or -C(=O)-NH-X 11 -, and the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * indicates a bond to a carbon atom in the main chain. A.L. 1 and A.L. 2 are each independently an acid labile group. R 11 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. a is an integer from 0 to 4.

7. The polymer according to claim 5 , further comprising a repeating unit represented by the following formula (c1): 【Chemistry 6】 (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, *-C(=O)-O-, or *-C(=O)-NH-. * represents a bond to a carbon atom in the main chain. R 21 represents a halogen atom, a nitro group, 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. c is an integer from 1 to 4. d is an integer from 0 to 3, provided that 1≦c+d≦5.

8. The polymer according to claim 5 , further comprising a repeating unit represented by the following formula (d1): 【Chemistry 7】 (In the formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z 1 is a single bond, a phenylene group, a naphthylene group, *-C(=O)-O-Z 11 - or -C(=O)-NH-Z 11 -, or the phenylene group or naphthylene group may be substituted with a halogen atom or an alkoxy group having 1 to 10 carbon atoms which may contain a fluorine atom. * represents a bond to a carbon atom of the main chain. Z 11 is a saturated hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group or a naphthylene group, and the saturated hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond or a lactone ring. R 31 is a hydrogen atom, or a group having 1 to 20 carbon atoms containing at least one structure selected from a hydroxy group other than a phenolic 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)-O-C(=O)-).

9. A chemically amplified resist composition comprising (A) a base polymer comprising the polymer of claim 5.

10. 10. The chemically amplified resist composition according to claim 9, further comprising (B) an organic solvent.

11. 10. The chemically amplified resist composition according to claim 9, further comprising (C) a quencher.

12. 10. The chemically amplified resist composition according to claim 9, further comprising (D) an acid generator.

13. 10. The chemically amplified resist composition according to claim 9, further comprising: (E) a surfactant.

14. 10. The chemically amplified resist composition according to claim 9, further comprising (F) a dissolution inhibitor.

15. A pattern forming method comprising the steps of: forming a resist film on a substrate using the chemically amplified resist composition according to claim 9; exposing the resist film to high-energy radiation; and developing the exposed resist film using a developer.

16. 16. The pattern forming method according to claim 15, wherein the high energy beam is an ArF excimer laser beam having a wavelength of 193 nm, a KrF excimer laser beam having a wavelength of 248 nm, an electron beam, or an extreme ultraviolet ray having a wavelength of 3 to 15 nm.

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