Resist material and pattern forming method

Abstract

To provide a resist material having improved LWR and CDU.SOLUTION: A resist material contains a base polymer, and an acid generator containing a sulfonium salt represented by the formula (A-1) or an iodonium salt represented by the formula (A-2).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resist material and a pattern forming method. [Background technology]

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

[0003] EUV resist materials must simultaneously achieve high sensitivity, high resolution, and low edge roughness (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.

[0004] EUV has a wavelength that is more than an order of magnitude shorter than ArF excimer laser light, and an order of magnitude higher in energy density. As a result, the number of photons that the photoresist layer is exposed to in EUV exposure is extremely small, at 1 / 14th that of ArF light, and it is said that the variation in photons affects the variation in dimensions (LWR and dimensional uniformity (CDU)). Furthermore, the variation in photons can cause a phenomenon in which hole patterns do not open with a probability of one in several million. It has been pointed out that in order to reduce the variation in photons, it is necessary to increase the light absorption of the photoresist material.

[0005] Acid generators that generate acid having a ring substituted with a fluorine atom have been proposed (Patent Documents 1 and 2). Fluorine atoms have the property of absorbing EUV, and acid generators incorporating fluorine atoms have improved acid generation efficiency upon EUV exposure. However, since fluorine atoms do not have the function of controlling acid diffusion, increased acid diffusion leads to deterioration of the LWR and CDU of the resist pattern after development. Although a rigid ring structure controls acid diffusion, this alone is not sufficient.

[0006] Acid generators that have a ring structure substituted with a fluorine atom at the end and generate sulfonic acid having a linker of a ring structure (Patent Document 3), acid generators that generate sulfonic acid having a lactone linker (Patent Document 4), and acid generators that generate sulfonic acid having a carbonate linker (Patent Document 5) have been proposed. Although the introduction of these linker structures shortens the acid diffusion, it is necessary to further control the acid diffusion. As miniaturization progresses, there is a demand to shorten the acid diffusion in chemically amplified resist materials to the limit. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2011-121937 A [Patent Document 2] JP 2020-015715 A [Patent Document 3] JP 2013-053137 A [Patent Document 4] JP 2020-063242 A [Patent Document 5] JP 2019-053287 A Summary of the Invention [Problem to be solved by the invention]

[0008] There is a demand for development of an acid generator for use in a resist material that has high sensitivity, reduces LWR, and improves CDU of a hole pattern.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resist material, whether positive or negative, which has high sensitivity and improved LWR and CDU, and a pattern formation method using the same. [Means for solving the problem]

[0010] As a result of intensive research into achieving the above-mentioned object, the present inventors have found that by using, as an acid generator, a sulfonium salt or iodonium salt of a fluorinated sulfonic acid having a fluorine atom-containing cyclic group and a phenylene group substituted with a nitro group, it is possible to obtain a resist material which has improved LWR and CDU, high contrast, excellent resolution and a wide process margin, and have completed the present invention.

[0011] That is, the present invention provides the following resist material and pattern forming method. 1. A resist material comprising a base polymer and an acid generator containing a sulfonium salt represented by the following formula (A-1) or an iodonium salt represented by the following formula (A-2): [ka] (In the formula, k is an integer of 0 to 2. p is an integer of 1 to 5. q is an integer of 0 to 4. r is 1 or 2. s is an integer of 0 to 3, with the proviso that 1≦r+s≦4. The circle R is a cyclic hydrocarbyl group having 6 to 14 carbon atoms. L 1 is a single bond, an ether bond, an ester bond, an amide bond, a carbonate bond, a urethane bond, a urea bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and the -CH 2 A portion of - may be substituted with an ether bond, an ester bond, an amide bond or a carbonate bond. L 2 is a single bond or a divalent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom. Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group. R f is a fluorine atom, a fluorinated alkyl group having 1 to 10 carbon atoms, a fluorinated alkyloxy group having 1 to 10 carbon atoms, a fluorinated alkylthio group having 1 to 10 carbon atoms, a fluorinated alkylcarbonyloxy group having 2 to 11 carbon atoms, a fluorinated alkylsulfonyloxy group having 1 to 10 carbon atoms, a fluorinated alkylcarbonylamino group having 2 to 11 carbon atoms, or a fluorinated alkylsulfonylamino group having 1 to 10 carbon atoms, some of the hydrogen atoms of these groups may be substituted with hydroxy groups. f may be bonded to form a ring together with the atoms to which they are attached. R 1 is a hydroxy group, a carboxy group, 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 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 chlorine atom, a bromine atom, a hydroxy group, an amino group, or an ether bond, or 1A )(R 1B ), -N(R 1C )-C(=O)-R 1D Or -N(R 1C )-C(=O)-OR 1D R 1A and R 1B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 1C 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. 1Dis an aliphatic hydrocarbyl group having 1 to 16 carbon atoms or an aryl group having 6 to 12 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. R 2 represents an alkyl group having 1 to 4 carbon atoms, an alkyloxy group having 1 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 5 carbon atoms, or a halogen atom. R 3 , R 4 , R 5 , R 6 and R 7 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 3 and R 4 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. 2. The resist material of 1, wherein the circle R is an aryl group having 6 to 14 carbon atoms. 3. The resist material of 1 or 2, wherein the base polymer contains a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. X 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing an ester bond, an ether bond, or a lactone ring. X 2 is a single bond or an ester bond. X 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and its -CH 2 A portion of - may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4. 4. The resist material of 3, which is a chemically amplified positive resist material. 5. The resist material of 1 or 2, wherein the base polymer does not contain an acid labile group. 6. The resist material of 5, which is a chemically amplified negative resist material. 7. The resist material according to any one of 1 to 6, wherein the base polymer contains a repeating unit represented by any one of the following formulas (f1) to (f3): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. Z 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these groups, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. 11 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group obtained by combining these and having 7 to 18 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Z 2 is a single bond or an ester bond. Z 3 is a single bond, -Z 31 -C(=O)-O-, -Z31 -O- or -Z 31 -OC(=O)-. Z 31 represents a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group obtained by combining these and having 7 to 18 carbon atoms, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. Z 5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a hydroxy group, or a halogen atom. R 21 ~R 28 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. M - is a non-nucleophilic counterion. 8. A resist material according to any one of 1 to 7, further comprising an organic solvent. 9. A resist material according to any one of 1 to 8, further comprising a quencher. 10. A resist material according to any one of 1 to 9, further comprising a surfactant. 11. A pattern forming method comprising the steps of forming a resist film on a substrate using a resist material according to any one of claims 1 to 10, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer. 12. The pattern formation method according to claim 11, 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. 13. The pattern formation method according to 11, wherein the high energy radiation is EB or EUV having a wavelength of 3 to 15 nm. Effect of the Invention

[0012] The sulfonium salt or iodonium salt of fluorinated sulfonic acid having a fluorine atom-containing cyclic group and a phenylene group substituted with a nitro group has the characteristic that the nitro group suppresses acid diffusion and makes the acid diffusion distance uniform. Furthermore, due to the polarization of the nitro group, secondary electrons are generated from the nitro group during exposure, resulting in high sensitivity. In addition, the repulsion of fluorine atoms does not cause aggregation, and the dispersibility is excellent. These make it possible to construct a resist material that is highly sensitive and has improved LWR and CDU. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Resist material] The resist material of the present invention includes a base polymer and an acid generator containing a sulfonium salt represented by formula (A-1) or an iodonium salt represented by formula (A-2). The sulfonium salt and the iodonium salt are acid generators that generate a fluorinated sulfonic acid having a fluorine atom-containing cyclic group and a phenylene group substituted with a nitro group (hereinafter, also referred to as fluorinated sulfonic acid FN) by irradiation with light. The resist material of the present invention may contain an acid generator that generates a different sulfonic acid, imide acid, or methide acid, or may be combined with a bound-type acid generator that is bonded to the base polymer.

[0014] When the sulfonium salt represented by formula (A-1) is mixed with a sulfonium salt of a weaker acid such as sulfonic acid or carboxylic acid, and the mixture is irradiated with light, fluorinated sulfonic acid FN and a weaker acid such as sulfonic acid or carboxylic acid are generated. Since not all acid generators are decomposed, there are acid generators nearby that are not decomposed. Here, when fluorinated sulfonic acid FN and a sulfonium salt of a weaker acid such as sulfonic acid or carboxylic acid coexist, ion exchange occurs between fluorinated sulfonic acid FN and a sulfonium salt of a weaker acid such as sulfonic acid or carboxylic acid, a salt of fluorinated sulfonic acid FN is generated, and the weak acid sulfonic acid or carboxylic acid is released. This is because the salt of fluorinated sulfonic acid FN, which has a high acid strength, is more stable. On the other hand, even if a sulfonium salt of fluorinated sulfonic acid FN and a weak acid such as sulfonic acid or carboxylic acid are present, ion exchange does not occur. This ion exchange based on the order of acid strength occurs not only in sulfonium salts, but also in the case of iodonium salts. When combined with an acid generator that is a sulfonium or iodonium salt of a fluorinated sulfonic acid FN, the sulfonium or iodonium salt of a weak acid functions as a quencher.

[0015] By improving the contrast of the optical image, the dissolution contrast of the resist film is improved, and the LWR and CDU are improved. Since light is both a wave and a particle, increasing the number of particles absorbed in the resist film also improves the dissolution contrast of the resist film, and thus improves the CDU and LWR.

[0016] Nitro groups are polarized into positive and negative charges, and secondary electrons are generated from the negatively charged parts during exposure, accelerating the decomposition of the acid generator and increasing sensitivity. In particular, the amount of secondary electrons generated from the nitro group increases when highly absorbing fluorine atoms are present nearby. This effect is particularly noticeable when the number of fluorine atom substitutions is three or more.

[0017] The sulfonium salt or iodonium salt of fluorinated sulfonic acid FN has a small acid diffusion because fluorine atoms and nitro groups that control acid diffusion are introduced into the anion, and furthermore, it has excellent dispersibility without aggregation due to the repulsion of fluorine atoms, which also improves LWR and CDU. The nitro group is highly hydrophilic, so it also has the effect of offsetting the decrease in solubility in alkaline developers caused by fluorine atoms.

[0018] The effect of improving LWR and CDU by the sulfonium salt or iodonium salt of fluorinated sulfonic acid FN is effective in both positive and negative pattern formation by alkaline aqueous solution development and negative pattern formation by organic solvent development.

[0019] [Sulfonium and iodonium salts of fluorinated sulfonic acids having a fluorine atom-containing cyclic group and a phenylene group substituted with a nitro group] The sulfonium salt and iodonium salt contained in the resist material of the present invention are represented by the following formulas (A-1) and (A-2), respectively. [ka]

[0020] In formulae (A-1) and (A-2), k is an integer of 0 to 2. p is an integer of 1 to 5. q is an integer of 0 to 4. r is 1 or 2.

[0021] In formulae (A-1) and (A-2), the circle R is a cyclic hydrocarbyl group having 6 to 14 carbon atoms. Examples of the cyclic hydrocarbyl group having 6 to 14 carbon atoms include cyclic saturated hydrocarbyl groups having 6 to 14 carbon atoms, such as a cyclohexyl group and an adamantyl group; and aryl groups having 6 to 14 carbon atoms, such as a phenyl group and a naphthyl group. Of these, the circle R is preferably an aryl group having 6 to 14 carbon atoms.

[0022] In formulas (A-1) and (A-2), L 1is a saturated hydrocarbylene group having 1 to 6 carbon atoms, which is a single bond, an ether bond, an ester bond, an amide bond, a carbonate bond, a urethane bond, or a urea bond, and the -CH 2 A part of the -CH in the saturated hydrocarbylene group may be substituted with an ether bond, an ester bond, an amide bond or a carbonate bond. 2 - may be located at the end thereof.

[0023] L 1 The saturated hydrocarbylene group having 1 to 6 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups having 1 to 6 carbon atoms, such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, and hexane-1,6-diyl group; cyclic saturated hydrocarbylene groups having 3 to 6 carbon atoms, such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; and groups obtained by combining these groups.

[0024] In formulas (A-1) and (A-2), L 2 is a single bond or a divalent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0025] Examples of the divalent linking group having 1 to 20 carbon atoms include an ester bond, an amide bond, and a hydrocarbylene group having 1 to 20 carbon atoms. The hydrocarbylene group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include a divalent linking group having 1 to 2 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, and a dodecane-1,12-diyl group. 0 alkanediyl group; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group; unsaturated aliphatic hydrocarbylene groups having 2 to 20 carbon atoms, such as vinylene group, propene-1,3-diyl group, and 2-butene-1,4-diyl group; arylene groups having 6 to 20 carbon atoms, such as phenylene group and naphthylene group; and groups obtained by combining these. 2 A part of -CH in the saturated hydrocarbylene group may be substituted with an ester bond, an ether bond, an amide bond, a sulfonate bond, or the like. 2 - may be located at the end thereof.

[0026] In the formulas (A-1) and (A-2), Rf 1 ~Rf 4 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. In particular, when k=0, Rf 3 and Rf 4 At least one of Rf is preferably a fluorine atom or a trifluoromethyl group, and when k=1, Rf 1 ~Rf 4 At least one of the groups is preferably a fluorine atom or a trifluoromethyl group, and when k=2, -SO 3 - Rf bonded to the β carbon of1 and Rf 2 and Rf 3 and Rf 4 It is preferable that at least one of the groups is a fluorine atom or a trifluoromethyl group.

[0027] In formulas (A-1) and (A-2), R f is a fluorine atom, a fluorinated alkyl group having 1 to 10 carbon atoms, a fluorinated alkyloxy group having 1 to 10 carbon atoms, a fluorinated alkylthio group having 1 to 10 carbon atoms, a fluorinated alkylcarbonyloxy group having 2 to 11 carbon atoms, a fluorinated alkylsulfonyloxy group having 1 to 10 carbon atoms, a fluorinated alkylcarbonylamino group having 2 to 11 carbon atoms, or a fluorinated alkylsulfonylamino group having 1 to 10 carbon atoms, some of the hydrogen atoms of these groups may be substituted with hydroxy groups. f may be bonded to form a ring together with the atoms to which they are attached.

[0028] The fluorinated alkyl group and the fluorinated alkyl moiety of the fluorinated alkyloxy group, fluorinated alkylthio group, fluorinated alkylcarbonyloxy group, fluorinated alkylsulfonyloxy group, fluorinated alkylcarbonylamino group and fluorinated alkylsulfonylamino group are alkyl groups having 1 to 10 carbon atoms in which at least one hydrogen atom has been substituted with a fluorine atom, and specific examples thereof include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, and a 1,1,1,3,3,3-hexafluoro-2-propyl group.

[0029] In formulas (A-1) and (A-2), R 1is 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 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 1A )(R 1B ), -N(R 1C )-C(=O)-R 1D Or -N(R 1C )-C(=O)-OR 1D R 1A and R 1B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 1C 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. 1D is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms or an aryl group having 6 to 12 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.

[0030] R 1The hydrocarbyl moiety of the hydrocarbyl group having 1 to 20 carbon atoms, the hydrocarbyloxy group having 1 to 20 carbon atoms, the hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, the hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, and the hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms represented by the following formula may be linear, branched, or cyclic, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, alkyl groups having 1 to 20 carbon atoms, such as an alkyl group, a tert-butyl group, a n-pentyl group, a n-hexyl group, a n-octyl group, a n-nonyl group, a 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-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, an azathioprine group, an aryl group, a tert-butyl group, a n-pentyl group, a n-hexyl group, a n-octyl group, a n-nonyl group, a 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; Cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a damantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 2 to 20 carbon atoms, such as a cyclohexenyl group and a norbornenyl group; alkynyl groups having 2 to 20 carbon atoms, such as an ethynyl group, a propynyl group, and a butynyl group; a phenyl group, a methylphenyl group, an ethylphenyl group, a n-propylphenyl group, an isopropylphenyl group, a n-butylphenyl group, Examples of the alkyl group include aryl groups having 6 to 20 carbon atoms, such as an nyl group, an isobutylphenyl group, a sec-butylphenyl group, a tert-butylphenyl group, a naphthyl group, a methylnaphthyl group, an ethylnaphthyl group, an n-propylnaphthyl group, an isopropylnaphthyl group, an n-butylnaphthyl group, an isobutylnaphthyl group, a sec-butylnaphthyl group, and a tert-butylnaphthyl group; aralkyl groups having 7 to 20 carbon atoms, such as a benzyl group and a phenethyl group; and groups obtained by combining these.

[0031] R 1A , R 1B and R 1CThe saturated hydrocarbyl group having 1 to 6 carbon atoms represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups; and cyclic saturated hydrocarbyl groups having 3 to 6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups. 1C Examples of the saturated hydrocarbyl moiety of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be contained in R include the same as the specific examples of the saturated hydrocarbyl group described above. 1C Examples of the saturated hydrocarbyl moiety of the saturated hydrocarbyl carbonyl group having 2 to 6 carbon atoms and the saturated hydrocarbyl carbonyloxy group having 2 to 6 carbon atoms that can be contained in include those having 1 to 5 carbon atoms among the specific examples of the saturated hydrocarbyl groups having 1 to 6 carbon atoms mentioned above.

[0032] R 1D The aliphatic 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 16 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, n-decyl, undecyl, dodecyl, tridecyl, tetradecyl, and pentadecyl groups; cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methyl, and the like. Examples of the alkyl groups include cyclic saturated hydrocarbyl groups having 3 to 16 carbon atoms, such as a cyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group; alkenyl groups having 2 to 16 carbon atoms, such as a vinyl group, a propenyl group, a butenyl group, and an hexenyl group; alkynyl groups having 2 to 20 carbon atoms, such as an ethynyl group, a propynyl group, and an butynyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 16 carbon atoms, such as a cyclohexenyl group and a norbornenyl group; and groups obtained by combining these groups. 1D Examples of the aryl group having 6 to 12 carbon atoms represented by the formula (R) include a phenyl group and a naphthyl group. 1DThe hydrocarbyl portion of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms that can be contained in R 1A , R 1B and R 1C Examples of the saturated hydrocarbyl group having 1 to 6 carbon atoms and represented by the formula (I) include the same as those exemplified above, and examples of the saturated hydrocarbyl moiety of the saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms or the saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms include those having 1 to 5 carbon atoms among the specific examples of the saturated hydrocarbyl group having 1 to 6 carbon atoms mentioned above.

[0033] In formulas (A-1) and (A-2), R 2 is an alkyl group having 1 to 4 carbon atoms, an alkyloxy group having 1 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 5 carbon atoms, or a halogen atom. The alkyl group and the alkyl moiety of the alkyloxy group and alkylcarbonyloxy group include 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. The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

[0034] In formulas (A-1) and (A-2), R 3 , R 4 , R 5 , R 6 and R 7 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom.

[0035] R 3 ~R 7 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0036] R 3 ~R 7The 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 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; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, or an adamantyl group; alkenyl groups having 2 to 20 carbon atoms, such as a vinyl group, a propenyl group, a butenyl group, or a hexenyl group; Examples of such groups include cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 20 carbon atoms, such as ethynyl, propynyl, and butynyl; alkynyl groups having 2 to 20 carbon atoms, such as phenyl, methylphenyl, ethylphenyl, n-propylphenyl, isopropylphenyl, n-butylphenyl, isobutylphenyl, sec-butylphenyl, tert-butylphenyl, naphthyl, methylnaphthyl, ethylnaphthyl, n-propylnaphthyl, isopropylnaphthyl, n-butylnaphthyl, isobutylnaphthyl, sec-butylnaphthyl, and tert-butylnaphthyl; aralkyl groups having 7 to 20 carbon atoms, such as benzyl and phenethyl; 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 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.

[0037] Also, R 3 and R 4 However, they may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring is preferably one having the structure shown below. [ka] (In the formula, the dashed line represents R 5 It is a bond with .)

[0038] Examples of the cation of the sulfonium salt represented by formula (A-1) include, but are not limited to, those shown below. [ka]

[0039] [ka]

[0040] [ka]

[0041] [ka]

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045]

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[0046]

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[0047]

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[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] Examples of the cation of the iodonium salt represented by formula (A-2) include, but are not limited to, those shown below. [ka]

[0063] [ka]

[0064] The anions of the sulfonium salt represented by formula (A-1) and the iodonium salt represented by formula (A-2) have a ring structure having a fluorine atom and a phenylene group substituted with a nitro group as a linker between the ring structure and the fluorosulfonic acid part, and the sulfonium salt represented by formula (A-1) and the iodonium salt represented by formula (A-2) are prevented from agglomerating by the absorption of EUV by the fluorine atom and the electrical repulsion of the fluorine atom, and are uniformly dispersed, resulting in uniform reaction points. Furthermore, the anions of the sulfonium salt represented by formula (A-1) and the iodonium salt represented by formula (A-2) have a nitro group, and therefore have an acid diffusion control ability.

[0065] Examples of the anion of the sulfonium salt represented by formula (A-1) and the iodonium salt represented by formula (A-2) include, but are not limited to, those shown below. [ka]

[0066] [ka]

[0067] [ka]

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072]

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[0073]

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[0074]

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[0075]

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[0076]

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[0077]

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[0078]

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[0079]

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[0080]

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[0081]

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[0082]

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[0083]

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[0084]

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[0085]

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[0086]

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[0087]

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[0088]

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[0089]

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[0090]

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[0091]

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[0092]

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[0093]

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[0094]

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[0095]

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[0096]

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[0097]

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[0098]

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[0099]

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[0100]

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[0101] The synthesis method of the sulfonium salt represented by formula (A-1) and the iodonium salt represented by formula (A-2) includes a method of ion-exchanging an ammonium salt of a fluorinated sulfonic acid with a sulfonium salt or an iodonium salt of an acid weaker than the fluorinated sulfonic acid. Examples of acids weaker than the fluorinated sulfonic acid include carbonic acid, halogen, and carboxylic acid. In addition, the synthesis can also be performed by ion-exchanging a sodium salt or an ammonium salt of a fluorinated sulfonic acid with a sulfonium chloride or an iodonium chloride.

[0102] In the resist material of the present invention, the content of the sulfonium salt represented by formula (A-1) or the iodonium salt represented by formula (A-2) is preferably 0.01 to 1,000 parts by mass, and more preferably 0.05 to 500 parts by mass, per 100 parts by mass of the base polymer described below, from the viewpoints of sensitivity and acid diffusion suppression effect.

[0103] [Base polymer] In the case of a positive resist material, the base polymer contained in the resist material of the present invention contains a repeating unit containing an acid labile group. The repeating unit containing an acid labile group is preferably a repeating unit represented by the following formula (a1) (hereinafter also referred to as repeating unit a1) or a repeating unit represented by the following formula (a2) (hereinafter also referred to as repeating unit a2). [ka]

[0104] In formulas (a1) and (a2), R A are each independently a hydrogen atom or a methyl group. 1 X is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and containing an ester bond, an ether bond, or a lactone ring. 2 is a single bond or an ester bond. 3 R is a single bond, an ether bond or an ester bond. 11 and R 12 R is each independently an acid labile group. 13R is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and its -CH 2 A part of - may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer of 0 to 4.

[0105] Examples of monomers that provide the repeating unit a1 include, but are not limited to, those shown below. A and R 11 is the same as above. [ka]

[0106] Examples of monomers that provide the repeating unit a2 include, but are not limited to, those shown below. A and R 12 is the same as above. [ka]

[0107] In formulas (a1) and (a2), R 11 and R 12 Examples of the acid labile group represented by the formula (I) include those described in JP-A-2013-80033 and JP-A-2013-83821.

[0108] Typically, the acid labile group includes those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0109] In formulas (AL-1) and (AL-2), R L1 and R L2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 40 carbon atoms, more preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms.

[0110] In formula (AL-1), c is an integer of 0 to 10, and an integer of 1 to 5 is preferable.

[0111] 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, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. 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.

[0112] 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, or a fluorine atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. The hydrocarbyl group is preferably a saturated hydrocarbyl group having 1 to 20 carbon atoms. L5 , R L6 and R L7Any 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.

[0113] The base polymer may contain a repeating unit b containing a phenolic hydroxy group as an adhesive group. Examples of monomers that provide the repeating unit b include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0114] The base polymer may contain a repeating unit c containing a hydroxy group other than a phenolic hydroxy group, a lactone ring, a sultone ring, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonyl group, a sulfonyl group, a cyano group, or a carboxy group as another adhesive group. Examples of monomers that provide the repeating unit c include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0115] [ka]

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120] [ka]

[0121] [ka]

[0122] The base polymer may include repeat units d derived from indene, benzofuran, benzothiophene, acenaphthylene, chromone, coumarin, norbornadiene, or derivatives thereof. Monomers that provide repeat units d include, but are not limited to, those shown below. [ka]

[0123] The base polymer may include repeat units e derived from styrene, vinyl naphthalene, vinyl anthracene, vinyl pyrene, methylene indane, vinyl pyridine, or vinyl carbazole.

[0124] The base polymer may contain a repeating unit f derived from an onium salt containing a polymerizable unsaturated bond. Preferred repeating units f include a repeating unit represented by the following formula (f1) (hereinafter also referred to as repeating unit f1), a repeating unit represented by the following formula (f2) (hereinafter also referred to as repeating unit f2), and a repeating unit represented by the following formula (f3) (hereinafter also referred to as repeating unit f3). The repeating units f1 to f3 may be used alone or in combination of two or more. [ka]

[0125] In formulas (f1) to (f3), R A are each independently a hydrogen atom or a methyl group. 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these groups, or -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. 11 Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these groups, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -OC(=O)-. Z 31 Z is a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. 5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -OZ 51 -, -C(=O)-OZ 51 - or -C(=O)-NH-Z 51 -It is. 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a hydroxy group, or a halogen atom.

[0126] In formulas (f1) to (f3), R 21 ~R 28are 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 3 ~R 7 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, 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. 23 and R 24 or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring may be any of the rings represented by R 3 and R 4 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.

[0127] In formula (f1), M -is a non-nucleophilic counter ion. Examples of the non-nucleophilic counter ion include halide ions such as chloride ion and bromide ion; fluoroalkylsulfonate ions such as triflate ion, 1,1,1-trifluoroethanesulfonate ion, and nonafluorobutanesulfonate ion; arylsulfonate ions such as tosylate ion, benzenesulfonate ion, 4-fluorobenzenesulfonate ion, and 1,2,3,4,5-pentafluorobenzenesulfonate ion; alkylsulfonate ions such as mesylate ion and butanesulfonate ion; imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, and bis(perfluorobutylsulfonyl)imide ion; and methide ions such as tris(trifluoromethylsulfonyl)methide ion and tris(perfluoroethylsulfonyl)methide ion.

[0128] Other examples of the non-nucleophilic counter ion include a sulfonate ion represented by the following formula (f1-1) in which the α-position is substituted with a fluorine atom, and a sulfonate ion represented by the following formula (f1-2) in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group. [ka]

[0129] In formula (f1-1), R 31 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms, and may contain an ether bond, an ester bond, a carbonyl group, a lactone ring or a fluorine atom.

[0130] In formula (f1-2), R 32 represents a hydrogen atom, a hydrocarbyl group having 1 to 30 carbon atoms, or a hydrocarbylcarbonyl group having 2 to 30 carbon atoms, and may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring.

[0131] R 31 or R 32The hydrocarbyl group and the hydrocarbyl moiety of the hydrocarbyl carbonyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, 2-ethylhexyl group, nonyl group, undecyl group, tridecyl group, pentadecyl group, heptadecyl group, and icosanyl group; cyclopentyl group, cyclohexyl group, 1-adamantyl group, 2-adamantyl group, and 1-adamantylmethyl group. cyclic saturated hydrocarbyl groups such as a norbornyl group, a norbornylmethyl group, a tricyclodecanyl group, a tetracyclododecanyl group, a tetracyclododecanylmethyl group, or a dicyclohexylmethyl group; alkenyl groups such as an allyl group; cyclic unsaturated hydrocarbyl groups such as a 3-cyclohexenyl group; aryl groups such as a phenyl group, a 1-naphthyl group, or a 2-naphthyl group; aralkyl groups such as a benzyl group or a diphenylmethyl group; and groups obtained by combining these.

[0132] In addition, some or all of the hydrogen atoms of the hydrocarbyl group or hydrocarbyl carbonyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2A part of 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 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, etc. Examples of hydrocarbyl groups containing heteroatoms include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, and a 3-oxocyclohexyl group.

[0133] Examples of the cation of the monomer that gives the repeating unit f1 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0134] Specific examples of the cation of the monomer that gives the repeating unit f2 or f3 include the same as those given as examples of the cation of the sulfonium salt represented by formula (A-1).

[0135] Examples of the anion of the monomer that gives the repeating unit f2 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0136] [ka]

[0137] [ka]

[0138] [ka]

[0139] [ka]

[0140] [ka]

[0141] [ka]

[0142] [ka]

[0143] [ka]

[0144] [ka]

[0145] [ka]

[0146] [ka]

[0147] Examples of the anion of the monomer that gives the repeating unit f3 include, but are not limited to, those shown below. In the following formula, RA is the same as described above. [Chemical formula]

[0148] By bonding an acid generator to the polymer main chain, acid diffusion can be reduced, and a decrease in resolution due to blurring of acid diffusion can be prevented. In addition, the LWR and CDU are improved by the uniform dispersion of the acid generator.

[0149] The base polymer for the positive resist material essentially contains a repeating unit a1 or a2 containing an acid-labile group. In this case, the content ratios of the repeating units a1, a2, b, c, d, e, and f are preferably 0 ≦ a1 < 1.0, 0 ≦ a2 < 1.0, 0 < a1 + a2 < 1.0, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.9, 0 ≦ d ≦ 0.8, 0 ≦ e ≦ 0.8, and 0 ≦ f ≦ 0.5, more preferably 0 ≦ a1 ≦ 0.9, 0 ≦ a2 ≦ 0.9, 0.1 ≦ a1 + a2 ≦ 0.9, 0 ≦ b ≦ 0.8, 0 ≦ c ≦ 0.8, 0 ≦ d ≦ 0.7, 0 ≦ e ≦ 0.7, and 0 ≦ f ≦ 0.4, and even more preferably 0 ≦ a1 ≦ 0.8, 0 ≦ a2 ≦ 0.8, 0.1 ≦ a1 + a2 ≦ 0.8, 0 ≦ b ≦ 0.75, 0 ≦ c ≦ 0.75, 0 ≦ d ≦ 0.6, 0 ≦ e ≦ 0.6, and 0 ≦ f ≦ 0.3. When the repeating unit f is at least one selected from the repeating units f1 to f3, f = f1 + f2 + f3. Also, a1 + a2 + b + c + d + e + f = 1.0.

[0150] On the one hand, for the base polymer for a negative resist material, an acid-labile group is not necessarily required. Examples of such base polymers include those containing repeating unit b and, optionally, further containing repeating units c, d, e, and / or f. The content ratios of these repeating units are preferably 0 < b ≤ 1.0, 0 ≤ c ≤ 0.9, 0 ≤ d ≤ 0.8, 0 ≤ e ≤ 0.8, and 0 ≤ f ≤ 0.5, more preferably 0.2 ≤ b ≤ 1.0, 0 ≤ c ≤ 0.8, 0 ≤ d ≤ 0.7, 0 ≤ e ≤ 0.7, and 0 ≤ f ≤ 0.4, and even more preferably 0.3 ≤ b ≤ 1.0, 0 ≤ c ≤ 0.75, 0 ≤ d ≤ 0.6, 0 ≤ e ≤ 0.6, and 0 ≤ f ≤ 0.3. When the repeating unit f is at least one selected from repeating units f1 to f3, f = f1 + f2 + f3. Also, b + c + d + e + f = 1.0.

[0151] To synthesize the base polymer, for example, monomers providing the aforementioned repeating units may be heated in an organic solvent with the addition of a radical polymerization initiator to conduct polymerization.

[0152] Examples of the organic solvent used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, dioxane, etc. Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, lauroyl peroxide, etc. The temperature during polymerization is preferably 50 to 80°C. The reaction time is preferably 2 to 100 hours, more preferably 5 to 20 hours.

[0153] When copolymerizing 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 before polymerization and then deprotected with a weak acid and water after polymerization, or it may be substituted with an acetyl group, a formyl group, a pivaloyl group, etc. and then subjected to alkaline hydrolysis after polymerization.

[0154] When hydroxystyrene or hydroxyvinylnaphthalene is copolymerized, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group may be deprotected by the above-mentioned alkaline hydrolysis to give hydroxystyrene or hydroxyvinylnaphthalene.

[0155] As the base for the alkaline hydrolysis, ammonia water, triethylamine, etc. can be used. The reaction temperature is preferably −20 to 100° C., more preferably 0 to 60° C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0156] The base polymer has a weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) using THF as a solvent of preferably 1,000 to 500,000, more preferably 2,000 to 30,000. When the Mw is within the above range, the resist film has good heat resistance and solubility in an alkaline developer.

[0157] In addition, when the base polymer has a wide molecular weight distribution (Mw / Mn), low and high molecular weight polymers are present, which may result in foreign matter being found on the pattern after exposure or deterioration of the pattern shape. As the pattern rule becomes finer, the effects of Mw and Mw / Mn tend to become greater, so in order to obtain a resist material suitable for fine pattern dimensions, it is preferable that the Mw / Mn of the base polymer has a narrow distribution of 1.0 to 2.0, particularly 1.0 to 1.5.

[0158] The base polymer may include two or more polymers having different composition ratios, Mw, and Mw / Mn.

[0159] [Organic solvents] The resist material of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve the above-mentioned components and the components described below. Examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, 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, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol Examples of the monoethyl ether include ethers such as propylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, 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; and lactones such as γ-butyrolactone.

[0160] In the resist material of the present invention, the content of the organic solvent is preferably 100 to 10,000 parts by mass, more preferably 200 to 8,000 parts by mass, based on 100 parts by mass of the base polymer. The organic solvent may be used alone or in combination of two or more kinds.

[0161] [Quencher] The resist material of the present invention may contain a quencher. The quencher refers to a compound that can trap the acid generated by the acid generator in the resist material, thereby preventing the acid from diffusing into unexposed areas.

[0162] The quencher may be a conventional basic compound. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond, or compounds having a carbamate group described in JP-A-3790649 are preferred. By adding such a basic compound, for example, the diffusion rate of the acid in the resist film can be further suppressed or the shape can be corrected.

[0163] Further, the quencher may be an onium salt such as a sulfonium salt, an iodonium salt, or an ammonium salt of a sulfonic acid or a carboxylic acid not fluorinated at the α-position, as described in JP-A-2008-158339. A sulfonic acid, an imide acid, or a methide acid having a fluorinated α-position is necessary for deprotecting an acid labile group of a carboxylic acid ester, but a sulfonic acid or a carboxylic acid not fluorinated at the α-position is released by salt exchange with an onium salt having a fluorinated α-position. A sulfonic acid or a carboxylic acid not fluorinated at the α-position does not cause a deprotection reaction, and therefore functions as a quencher.

[0164] Examples of such quenchers include a compound represented by the following formula (B) (an onium salt of a sulfonic acid not fluorinated at the α-position) and a compound represented by the following formula (C) (an onium salt of a carboxylic acid). [ka]

[0165] In formula (B), R 101represents 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.

[0166] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0]. 2,6 ]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms, such as decanyl group, adamantyl group, and adamantylmethyl group; alkenyl groups having 2 to 40 carbon atoms, such as vinyl group, allyl group, propenyl group, butenyl group, and hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 40 carbon atoms, such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-n-butylphenyl group, Examples of such groups include aryl groups having 6 to 40 carbon atoms, such as arylphenyl groups (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl groups (methylnaphthyl group, ethylnaphthyl group, etc.), and dialkylnaphthyl groups (dimethylnaphthyl group, diethylnaphthyl group, etc.); heteroaryl groups, such as thienyl group; aralkyl groups having 7 to 40 carbon atoms, such as benzyl group, 1-phenylethyl group, 2-phenylethyl group; and groups obtained by combining these groups.

[0167] 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 -CH2 A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a 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. Examples of hydrocarbyl groups containing heteroatoms include alkoxyphenyl groups such as 4-hydroxyphenyl group, 4-methoxyphenyl group, 3-methoxyphenyl group, 2-methoxyphenyl group, 4-ethoxyphenyl group, 4-tert-butoxyphenyl group, and 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as methoxynaphthyl group, ethoxynaphthyl group, n-propoxynaphthyl group, and n-butoxynaphthyl group; dialkoxynaphthyl groups such as dimethoxynaphthyl group and diethoxynaphthyl group; and aryloxoalkyl groups such as 2-aryl-2-oxoethyl group, 2-(1-naphthyl)-2-oxoethyl group, and 2-(2-naphthyl)-2-oxoethyl group.

[0168] In formula (C), R 102 R is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. 102 The hydrocarbyl group represented by R 101 Examples of the hydrocarbyl group include the same as those exemplified above. Other specific examples include fluorine-containing alkyl groups such as a trifluoromethyl group, a trifluoroethyl group, a 2,2,2-trifluoro-1-methyl-1-hydroxyethyl group, and a 2,2,2-trifluoro-1-(trifluoromethyl)-1-hydroxyethyl group; and fluorine-containing aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0169] In formulas (B) and (C), Mq +is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. Examples of the sulfonium cation or the iodonium cation include the same as those exemplified as the cation of the sulfonium salt represented by formula (A-1) and the same as those exemplified as the cation of the iodonium salt represented by formula (A-2).

[0170] As the quencher, a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (D) can also be suitably used. [ka]

[0171] In formula (D), R 201 represents a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, in which some or all of the hydrogen atoms may be substituted with halogen atoms, or -N(R 201A )(R 201B ), -N(R 201C )-C(=O)-R 201D Or -N(R 201C )-C(=O)-OR 201D R 201A and R 201B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 201C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 201D is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group and saturated hydrocarbylsulfonyloxy group may be linear, branched or cyclic. When y and / or z is 2 or more, each R201 may be the same or different from each other.

[0172] In formula (D), x is an integer of 1 to 5. y is an integer of 0 to 3. z is an integer of 1 to 3. L 11 is a single bond or a (z+1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one bond selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group.

[0173] In formula (D), R 202 , R 203 and R 204 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 3 ~R 7 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, an oxo group, a cyano group, a nitro 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. 202 and R 203 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring may be any of the groups represented by R 3 and R 4 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.

[0174] Specific examples of the compound represented by formula (D) include those described in JP-A-2017-219836.

[0175] Further examples of the quencher include polymer-type quenchers described in JP 2008-239918 A. These improve the rectangularity of the resist pattern by orienting on the surface of the resist film after coating. Polymer-type quenchers also have the effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for immersion exposure is applied.

[0176] When the resist composition of the present invention contains the quencher, the content thereof is preferably from 0 to 20 parts by mass, and more preferably from 0.1 to 10 parts by mass, relative to 100 parts by mass of the base polymer.

[0177] [Other ingredients] The resist material of the present invention may contain, in addition to the above-mentioned components, an acid generator other than the sulfonium salt represented by formula (A-1) or the iodonium salt represented by formula (A-2) (hereinafter referred to as "other acid generators"), a surfactant, a dissolution inhibitor, a crosslinking agent, a water repellency enhancer, acetylene alcohols, etc.

[0178] The other acid generators include compounds (photoacid generators) that generate acid in response to actinic rays or radiation. The photoacid generator may be any compound that generates acid upon exposure to high-energy rays, but is preferably an acid generator that generates sulfonic acid, imide acid, or methide acid. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate acid generators. Specific examples of acid generators are described in paragraphs

[0122] to

[0142] of JP-A-2008-111103, JP-A-2018-5224, and JP-A-2018-25789. When the resist material of the present invention contains another acid generator, the content thereof is preferably 0 to 200 parts by mass, and more preferably 0.1 to 100 parts by mass, relative to 100 parts by mass of the base polymer. The other acid generators may be used alone or in combination of two or more.

[0179] Examples of the surfactant include those described in paragraphs

[0165] to

[0166] of JP 2008-111103 A. The addition of a surfactant can further improve or control the coatability of the resist material. When the resist material of the present invention contains the surfactant, the content thereof is preferably 0.0001 to 10 parts by mass relative to 100 parts by mass of the base polymer. The surfactant may be used alone or in combination of two or more kinds.

[0180] When the resist material of the present invention is a positive type, the difference in dissolution rate between the exposed and unexposed areas can be further increased by adding a dissolution inhibitor, and the resolution can be further improved. The dissolution inhibitor includes a compound having a molecular weight of preferably 100 to 1,000, 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 containing 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 bisphenol A, trisphenol, phenolphthalein, cresol novolac, naphthalene carboxylic acid, adamantane carboxylic acid, hydroxyl groups of cholic acid, and compounds in which hydrogen atoms of carboxyl groups are substituted with acid labile groups, and the like, and are described, for example, in paragraphs

[0155] to

[0178] of JP-A-2008-122932.

[0181] When the resist material of the present invention is a positive type and contains the dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass, based on 100 parts by mass of the base polymer. The dissolution inhibitor may be used alone or in combination of two or more kinds.

[0182] On the other hand, when the resist material of the present invention is a negative type, a crosslinking agent can be added to reduce the dissolution rate of the exposed area to obtain a negative type pattern. Examples of the crosslinking agent include epoxy compounds, melamine compounds, guanamine compounds, glycoluril compounds or urea compounds, isocyanate compounds, azide compounds, and compounds containing double bonds such as alkenyloxy groups, which are substituted with at least one group selected from methylol groups, alkoxymethyl groups, and acyloxymethyl groups. These may be used as additives, or may be introduced as pendant groups into the polymer side chain. Compounds containing hydroxyl groups may also be used as crosslinking agents.

[0183] Examples of the epoxy compound include tris(2,3-epoxypropyl)isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0184] Examples of the melamine compound include hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are acyloxymethylated or a mixture thereof, and the like.

[0185] Examples of the guanamine compound include tetramethylol guanamine, tetramethoxymethyl guanamine, a compound in which 1 to 4 methylol groups of tetramethylol guanamine are methoxymethylated or a mixture thereof, tetramethoxyethyl guanamine, tetraacyloxyguanamine, a compound in which 1 to 4 methylol groups of tetramethylol guanamine are acyloxymethylated or a mixture thereof, and the like.

[0186] Examples of glycoluril compounds include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, compounds in which 1 to 4 methylol groups of tetramethylol glycoluril are methoxymethylated or mixtures thereof, compounds in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated or mixtures thereof, etc. Examples of urea compounds include tetramethylol urea, tetramethoxymethyl urea, compounds in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated or mixtures thereof, tetramethoxyethyl urea, etc.

[0187] Examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0188] Examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0189] Examples of compounds containing an alkenyloxy group include ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether.

[0190] When the resist composition of the present invention is a negative type and contains the crosslinking agent, the content thereof is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, based on 100 parts by mass of the base polymer. The crosslinking agent may be used alone or in combination of two or more kinds.

[0191] The water repellency improver improves the water repellency of the resist film surface, and 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, and the like are preferred, and those exemplified in JP-A-2007-297590 and JP-A-2008-111103 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 the 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 resist composition of the present invention contains the water repellency improver, the content thereof is preferably 0 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, based on 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more kinds.

[0192] The acetylene alcohols include those described in paragraphs

[0179] to

[0182] of JP 2008-122932 A. When the resist material of the present invention contains an acetylene alcohol, the content is preferably 0 to 5 parts by mass relative to 100 parts by mass of the base polymer. The acetylene alcohols may be used alone or in combination of two or more kinds.

[0193] [Pattern formation method] When the resist material of the present invention is used in various integrated circuit manufacturing, known lithography techniques can be applied.For example, as a pattern forming method, the method includes the steps of forming a resist film on a substrate using the above-mentioned resist material, exposing the resist film to high-energy radiation, and developing the exposed resist film using a developer.

[0194] First, the resist material 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 as to give a coating thickness of 0.01 to 2 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.

[0195] 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 1,000 μC / cm 2 Approximately, more preferably 0.5 to 200 μC / cm 2The resist material of the present invention is suitable for fine patterning using high energy rays, particularly i-rays with a wavelength of 365 nm, KrF excimer laser light, ArF excimer laser light, EB, EUV, X-rays, soft X-rays, γ-rays, and synchrotron radiation, and is particularly suitable for fine patterning using EB or EUV.

[0196] After the exposure, PEB may be performed on a hot plate or in an oven, preferably at 50 to 150° C. for 10 seconds to 30 minutes, more preferably at 60 to 120° C. for 30 seconds to 20 minutes.

[0197] After exposure or PEB, the exposed resist film is developed by a conventional method such as a dip method, a puddle method, or a spray method using a developer of an alkaline aqueous solution of 0.1 to 10 mass%, preferably 2 to 5 mass%, such as tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), or tetrabutylammonium hydroxide (TBAH) for 3 seconds to 3 minutes, preferably 5 seconds to 2 minutes, to form a desired pattern. In the case of a positive resist material, the portion irradiated with light dissolves in the developer, and the portion not exposed to light does not dissolve, forming a desired positive pattern on the substrate. In the case of a negative resist material, the opposite is true to the case of a positive resist material, where the portion irradiated with light becomes insoluble in the developer, and the portion not exposed to light dissolves.

[0198] A negative pattern can also be obtained by organic solvent development using a positive resist material containing a base polymer containing an acid labile group. The developer used in this case is 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, 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.

[0199] At the end of the development, rinsing is 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.

[0200] Specific examples of alcohols 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. , 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.

[0201] 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.

[0202] Examples of alkanes having 6 to 12 carbon atoms include hexane, heptane, octane, nonane, decane, undecane, dodecane, methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, cycloheptane, cyclooctane, cyclononane, etc. Examples of alkenes having 6 to 12 carbon atoms include hexene, heptene, octene, cyclohexene, methylcyclohexene, dimethylcyclohexene, cycloheptene, cyclooctene, etc. Examples of alkynes having 6 to 12 carbon atoms include hexine, heptine, octyne, etc.

[0203] Examples of aromatic solvents include toluene, xylene, ethylbenzene, isopropylbenzene, tert-butylbenzene, and mesitylene.

[0204] 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.

[0205] 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

[0206] 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.

[0207] The structures of the sulfonium salt or iodonium salt acid generators PAG-1 to PAG-22 used in the resist materials are shown below. PAG-1 to PAG-22 were synthesized by ion exchange between the ammonium salt of a fluorinated sulfonic acid, which gives the anion shown below, and a sulfonium chloride or an iodonium chloride, which gives the cation shown below. [ka]

[0208] [ka]

[0209] [ka]

[0210] [ka]

[0211] [ka]

[0212] [ka]

[0213] [Synthesis Example] Synthesis of base polymers (polymers P-1 to P-4) Each monomer was combined and copolymerized in THF as a solvent, the reaction solution was poured into methanol, and the precipitated solid was washed with hexane, isolated, and dried to obtain base polymers (polymers P-1 to P-4) with the following compositions. The resulting base polymers had the following compositions: 1 Mw and Mw / Mn were confirmed by H-NMR and GPC (solvent: THF, standard: polystyrene). [ka]

[0214] [Examples 1 to 25, Comparative Examples 1 to 3] Preparation of resist materials and their evaluation (1) Preparation of resist material A resist material was prepared by filtering a solution obtained by dissolving each component in the composition shown in Table 1 in a solvent containing 100 ppm of Polyfox PF-636 (manufactured by Omnova) as a surfactant through a 0.2 μm filter.

[0215] In Table 1, the components are as follows. Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) EL (D-form, ethyl lactate) DAA (Diacetone Alcohol)

[0216] Comparative acid generator: cPAG-1, cPAG-2 [ka]

[0217] Quencher: Q-1, Q-2 [ka]

[0218] (2) EUV lithography evaluation Each resist material shown in Table 1 was spin-coated on 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. was formed to a thickness of 20 nm, and the substrate was pre-baked at 105°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 light using an EUV scanner NXE3400 manufactured by ASML (NA 0.33, σ 0.9 / 0.6, quadruple pole illumination, a mask with a hole pattern with a pitch of 40 nm on the wafer and a +20% bias), and PEB was performed on a hot plate at the temperature shown in Table 1 for 60 seconds, and development was performed with a 2.38% by mass TMAH aqueous solution for 30 seconds to obtain hole patterns with a size of 20 nm in Examples 1 to 24 and Comparative Examples 1 and 2, and dot patterns with a size of 20 nm in Example 25 and Comparative Example 3. Using a Hitachi High-Technologies Corporation CD-SEM (CG6300), the amount of exposure when holes or dots were formed at 20 nm was measured and used as the sensitivity, and the dimensions of 50 holes or dots were measured, and the standard deviation (σ) calculated from the results was tripled (3σ) to give the dimensional variation (CDU). The results are shown in Table 1.

[0219] [Table 1]

[0220] The results shown in Table 1 show that the resist material of the present invention, which contains a sulfonium salt represented by formula (A-1) or an iodonium salt represented by formula (A-2) as an acid generator, has high sensitivity and good CDU.

Claims

1. A resist material comprising a base polymer and an acid generator containing a sulfonium salt represented by the following formula (A-1) or an iodonium salt represented by the following formula (A-2): 【Chemistry 1】 (In the formula, k is an integer of 0 to 2, p is an integer of 1 to 5, q is an integer of 0 to 4, r is 1 or 2, and s is an integer of 0 to 3, with the proviso that 1≦r+s≦4. The circle R is a cyclic hydrocarbyl group having 6 to 14 carbon atoms. L 1 is a single bond, an ether bond, an ester bond, an amide bond, a carbonate bond, a urethane bond, a urea bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms, and the —CH 2 A part of the - may be substituted with an ether bond, an ester bond, an amide bond or a carbonate bond. L 2 is a single bond or a divalent linking group having 1 to 20 carbon atoms, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom. Rf 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group. R f is a fluorine atom, a fluorinated alkyl group having 1 to 10 carbon atoms, a fluorinated alkyloxy group having 1 to 10 carbon atoms, a fluorinated alkylthio group having 1 to 10 carbon atoms, a fluorinated alkylcarbonyloxy group having 2 to 11 carbon atoms, a fluorinated alkylsulfonyloxy group having 1 to 10 carbon atoms, a fluorinated alkylcarbonylamino group having 2 to 11 carbon atoms, or a fluorinated alkylsulfonylamino group having 1 to 10 carbon atoms, some of the hydrogen atoms of these groups may be substituted with hydroxy groups. f may be bonded to form a ring together with the atoms to which they are attached. R 1 is a hydroxy group, a carboxy group, 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 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 chlorine atom, a bromine atom, a hydroxy group, an amino group, or an ether bond, or 1A ) (R 1B ), -N(R 1C )-C(=O)-R 1D Or -N(R 1C )-C(=O)-OR 1D It is. 1A and R 1B are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 1C 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. R 1D is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms or an aryl group having 6 to 12 carbon atoms, which 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. R 2 represents an alkyl group having 1 to 4 carbon atoms, an alkyloxy group having 1 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 5 carbon atoms, or a halogen atom. R 3 , R 4 , R 5 , R 6 and R 7 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 3 and R 4 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.)

2. 2. The resist material according to claim 1, wherein the circle R is an aryl group having 6 to 14 carbon atoms.

3. The resist material according to claim 1 , wherein the base polymer contains a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2): 【Chemistry 2】 (In the formula, R A are each independently a hydrogen atom or a methyl group. X 1 is a linking group having 1 to 12 carbon atoms which includes a single bond, a phenylene group, a naphthylene group, an ester bond, an ether bond, or a lactone ring. X 2 is a single bond or an ester bond. X 3 is a single bond, an ether bond or an ester bond. R 11 and R 12 are each independently an acid labile group. R 13 is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. R 14 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, 2 A part of the - may be substituted with an ether bond or an ester bond. a is 1 or 2. b is an integer from 0 to 4.

4. The resist material of claim 3 which is a chemically amplified positive resist material.

5. 2. The resist material of claim 1, wherein the base polymer does not contain an acid labile group.

6. 6. The resist material of claim 5 which is a chemically amplified negative resist material.

7. The resist material according to claim 1, wherein the base polymer contains a repeating unit represented by any one of the following formulas (f1) to (f3): 【Chemistry 3】 (In the formula, R A are each independently a hydrogen atom or a methyl group. Z 1 represents a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -O-Z 11 -, -C(=O)-O-Z 11 - or -C(=O)-NH-Z 11 - is. 11 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. Z 2 is a single bond or an ester bond. Z 3 is a single bond, -Z 31 -C(=O)-O-, -Z 31 -O- or -Z 31 -O-C(=O)-. Z 31 represents a hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group obtained by combining these and having 7 to 18 carbon atoms, which may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z 4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. Z 5 represents a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O-Z 51 -, -C(=O)-O-Z 51 - or -C(=O)-NH-Z 51 - is. 51 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a hydroxy group, or a halogen atom. R 21 ~R 28 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23 and R 24 Or R 26 and R 27 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. M - is a non-nucleophilic counterion.)

8. The resist material according to claim 1, further comprising an organic solvent.

9. The resist material according to claim 1, further comprising a quencher.

10. The resist material according to claim 1, further comprising a surfactant.

11. A pattern forming method comprising the steps of: forming a resist film on a substrate using the resist material according to any one of claims 1 to 10; exposing the resist film to high-energy radiation; and developing the exposed resist film using a developer.

12. 12. The method for forming a pattern according to claim 11, wherein the high-energy radiation is an ArF excimer laser beam having a wavelength of 193 nm or a KrF excimer laser beam having a wavelength of 248 nm.

13. 12. The pattern formation method according to claim 11, wherein the high-energy beam is an electron beam or extreme ultraviolet light having a wavelength of 3 to 15 nm.

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