Patterning process and resist material

Abstract

To provide a patterning process according to which a fine pattern can be formed with a high aspect ratio and without pattern collapse occurring.SOLUTION: A patterning process includes: providing a resist material containing a polymer in which a carboxy group bonded to a polymer main chain is protected with an acid-labile group; forming a resist film by using the resist material; and subjecting the resist film to exposure and heating, and then to development by dry etching to form a pattern, wherein, as the polymer, a polymer having one or both of repeating units having a phenolic hydroxyl group and a naphtholic hydroxyl group on a side chain is used.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] As LSIs become more highly integrated and faster, pattern rules are becoming increasingly miniaturized. This is due to the increasing popularity of 5G high-speed communications and artificial intelligence (AI), which require high-performance devices to process these technologies. The most advanced miniaturization technology is extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm, which is currently used to mass-produce 5nm and 3nm node devices. Furthermore, the use of EUV lithography is being considered for next-generation 2nm node devices and the generation after that, the 14Å node, with Belgium's IMEC announcing the development of 2Å devices.

[0003] As miniaturization progresses, image blurring due to acid diffusion has become a problem. To ensure resolution in fine patterns with dimensions of 45 nm and smaller, it has been suggested that controlling acid diffusion is important, in addition to improving dissolution contrast, as has been proposed previously (Non-Patent Document 1). However, because chemically amplified resist materials increase sensitivity and contrast through acid diffusion, attempts to minimize acid diffusion by lowering the post-exposure bake (PEB) temperature or shortening the time result in significant decreases in sensitivity and contrast.

[0004] The triangle trade-off relationship between sensitivity, resolution, and edge roughness (LWR) is shown. To improve resolution, it is necessary to suppress acid diffusion, but as the acid diffusion distance becomes shorter, sensitivity decreases.

[0005] It is effective to suppress acid diffusion by adding an acid generator that generates bulky acid. Therefore, it has been proposed to incorporate repeating units derived from onium salts having polymerizable unsaturated bonds into a polymer. In this case, the polymer also functions as an acid generator (polymer-bound acid generator). Patent Document 1 proposes sulfonium salts and iodonium salts having polymerizable unsaturated bonds that generate specific sulfonic acids. Patent Document 2 proposes sulfonium salts in which sulfonic acids are directly linked to the main chain.

[0006] It has been reported that pattern collapse determines the resolution limit of resists (Non-Patent Document 1). The pattern collapse occurs due to stress applied to the pattern during spin drying after rinsing in alkaline water development. Lowering the surface tension of the rinse solution is effective in reducing stress during spin drying, and rinse solutions containing surfactants have been used for this purpose, but this is insufficient for line patterns with a pattern pitch of 20 nm or less. Rinsing with supercritical carbon dioxide, which reduces surface tension to zero, has been considered, but this requires a special chamber to create a high-pressure supercritical state, making it impractical from the perspective of improving throughput. A method has been proposed in which the gaps between patterns are filled with a water-soluble silicon-containing rinse solution and then dry-etched with oxygen gas, but this method suffers from the problem of image inversion.

[0007] A pattern formation method has been proposed in which the exposed portions are opened by dry etching a resist pattern in which the exposed portions have shrunk due to exposure and deprotection of acid labile groups by PEB (Patent Document 3). If the amount of shrinkage of the exposed portions is large, problems arise such as deformation of two-dimensional patterns such as L-shapes, or the cross-sectional shape of lines becoming triangular. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-045311 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-178317 [Patent Document 3] Japanese Patent Application Publication No. 2023-157346 [Non-patent literature]

[0009] [Non-Patent Document 1] SPIE Vol. 6153 p61531C-1 (2006) Summary of the Invention [Problem to be solved by the invention]

[0010] As mentioned above, as pattern rules become finer in line with the increasing integration and speed of LSIs, there is a demand for a pattern formation method that does not cause pattern collapse or deformation.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pattern forming method capable of forming a fine pattern with a high aspect ratio without causing pattern collapse. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides a pattern formation method including: preparing a resist material containing a polymer in which a carboxyl group bonded to a polymer main chain is protected by an acid labile group; forming a resist film using the resist material; exposing and heating the resist film; and developing the resist film by dry etching to form a pattern, The present invention provides a pattern forming method characterized in that the polymer used has one or both of repeating units represented by the following general formulae (a1) and (a2): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 and R 2are each independently a linear, branched, or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to form a ring. 4 R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. 3 and R 5 are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl (CF3) group, a trifluoromethoxy (CF3O) group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each integers of 1 to 3, and p and q are each integers of 0 to 6. X 1 is a single bond, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group.

[0013] The pattern forming method of the present invention can form a fine pattern with a high aspect ratio without causing pattern collapse.

[0014] In this case, the resist material may further contain an acid generator, or may contain a polymer having a repeating unit b having an acid generating moiety in addition to the repeating unit described above, or may be a combination of both.

[0015] In the present invention, the acid-generating function of the resist material can be optimized by incorporating an acid generator into the resist material (external addition), by using a polymer incorporating an acid-generating moiety (polymer-bound acid generator) (internal addition), or by combining these methods.

[0016] When using a polymer incorporating a repeating unit b having an acid generating moiety, it is preferable to use a repeating unit selected from the repeating units represented by the following formulas (b1) to (b5) as the repeating unit b having an acid generating moiety. [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. B are each independently a hydrogen atom or Z 6 may be bonded to form a ring. 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 -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 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, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O- or -Z 31 -O-. Z 31 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, a nitro group, a cyano group, an ester bond, an ether bond, a urethane bond, a fluorine atom, an iodine atom, or a bromine atom. Z 4 is a single bond, a methylene group, or an ethylene group. 5represents a single bond, a methylene group, an ethylene group, a phenylene group, a methylphenylene group, a dimethylphenylene 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. Z 51 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a methylphenylene group, a dimethylphenylene 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. 6 is a single bond, a phenylene group, a naphthylene ring, an ester bond or an amide bond. 7A represents a single bond or a divalent organic group having 1 to 24 carbon atoms, and may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. 7B is a monovalent organic group having 1 to 10 carbon atoms, which may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. 8 is a single bond, an ether bond, an ester bond, a thioether bond, or an alkanediyl group having 1 to 6 carbon atoms. 9 is a trivalent organic group having 1 to 12 carbon atoms, and may have at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine with the carbon atom to which they are attached to form a carbonyl group. 21 and R 22 R are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23is a saturated hydrocarbyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a fluorine atom, an iodine atom, a trifluoromethoxy group, a difluoromethoxy group, a cyano group, or a nitro group. Ring R is a (d+2)-valent aromatic hydrocarbon group having 6 to 10 carbon atoms. d is an integer of 0 to 5. X - is a non-nucleophilic counterion. M + is a sulfonium cation or an iodonium cation.

[0017] In the present invention, by using a polymer incorporating a repeating unit b having such an acid generating moiety, it is possible to more preferably form a fine pattern with a high aspect ratio without pattern collapse.

[0018] In this case, the repeating unit b having the acid generating moiety is Z in the above formula. 3 , Z 7A , Z 7B or M + However, repeat units containing one or more iodine atoms can be used.

[0019] By using such a repeating unit containing an iodine atom, more suitable pattern formation becomes possible.

[0020] In the present invention, the exposure can also be carried out using extreme ultraviolet light having a wavelength of 3 to 15 nm or an electron beam having an acceleration voltage of 1 to 150 kV.

[0021] In the present invention, such high-energy rays can be used to more preferably form a fine pattern with a high aspect ratio without causing pattern collapse.

[0022] The present invention also provides a resist material for use in pattern formation by dry etching, which resist material contains a polymer having either or both of repeating units represented by the following general formulae (a1) and (a2): [ka] (In the formula, RA are each independently a hydrogen atom or a methyl group. 1 and R 2 are each independently a linear, branched, or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to form a ring. 4 R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. 3 and R 5 are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each integers of 1 to 3, and p and q are each integers of 0 to 6. X 1 is a single bond, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group.

[0023] Such a resist material can be suitably used in the pattern forming method of the present invention. [Effects of the Invention]

[0024] In the pattern formation method of the present invention, when acid is generated in the resist film by exposure, acid-labile groups containing phenol groups in the polymer are deprotected to generate carboxyl groups. When a positive resist material is used, dry etching is performed to open the exposed areas where carboxyl groups have been generated, forming a positive pattern. Radicals generated in the dry etching chamber increase the etching rate in the exposed areas due to main chain decomposition and carbon dioxide generation, while the etching rate in the unexposed areas decreases due to the absorption of radicals by the phenol groups. A positive pattern is formed by increasing the difference in etching rate between the exposed and unexposed areas. Development by dry etching does not cause pattern collapse due to capillary force, making it possible to form fine patterns with high aspect ratios. DETAILED DESCRIPTION OF THE INVENTION

[0025] As mentioned above, as pattern rules become finer in line with the increasing integration and speed of LSIs, there has been a demand for a pattern formation method that does not cause pattern collapse or deformation.

[0026] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that by using a resist material based on a polymer having a repeating unit in which a carboxyl group is protected with an acid labile group having a phenol group, the unexposed parts have phenol groups, and carboxyl groups are generated by deprotection in the exposed parts, and when this is dry etched, radicals generated in the etching chamber are absorbed by phenol, slowing the etching rate of the unexposed parts, while the exposed parts have a faster etching rate accompanied by decarboxylation and main chain decomposition, thereby increasing the etching rate selectivity between the exposed and unexposed parts without relying on film shrinkage in the exposed parts, and making it possible to form a fine pattern with a high aspect ratio, thereby completing the present invention.

[0027] That is, the present invention relates to a pattern formation method comprising the steps of preparing a resist material containing a polymer (base polymer) in which a carboxyl group bonded to the polymer main chain is protected by an acid labile group, forming a resist film using the resist material, exposing and heating the resist film, and developing the resist film by dry etching to form a pattern, wherein the polymer used is a polymer having a specific repeating unit described below. Note that hereinafter, the base polymer may also be referred to as a base resin.

[0028] The present invention will be described in detail below, but the present invention is not limited thereto. In this specification, the descriptions using endpoints of numerical ranges include all values ​​included in that range.

[0029] [Pattern formation method] The pattern forming method of the present invention includes the following steps (i) to (iv): (i) preparing a resist material comprising a polymer in which a carboxyl group attached to the polymer main chain is protected by an acid labile group; (ii) forming a resist film using the resist material and exposing the resist film; (iii) a step of baking the exposed resist film; (iv) A pattern forming method comprising a step of developing the heated resist film by dry etching to form a pattern, The polymer used has repeating units represented by the following general formulae (a1) and (a2), or both of them. [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 and R 2 are each independently a linear, branched, or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R 1 and R2 may be bonded to form a ring. 4 R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. 3 and R 5 are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each integers of 1 to 3, and p and q are each integers of 0 to 6. X 1 is a single bond, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group.

[0030] [Step (i)] Step (i) is a step of preparing a resist material containing a polymer (base resin) in which carboxyl groups attached to the polymer main chain are protected by acid labile groups. The resist material will be described in detail later.

[0031] [Step (ii)] In step (ii), a resist film is formed using the resist material, and the resist film is exposed to light. The resist film can be formed, for example, by applying a resist material containing the base resin onto a substrate and then subjecting the substrate to a heat treatment.

[0032] Specifically, for example, the resist material is applied to a substrate for integrated circuit manufacturing or a process layer on the substrate (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coating, etc.), or to a substrate for mask circuit manufacturing or a process layer on the substrate (Cr, CrO, CrON, MoSi2, SiO2, Ru, Ta, TaB, TaBN, TaBO, etc.) by an appropriate coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., to a coating thickness of 0.1 to 2.0 μm. This is then pre-baked on a hot plate at 60 to 150°C for 10 seconds to 30 minutes, preferably 80 to 120°C for 30 seconds to 20 minutes, to form a resist film.

[0033] Next, the resist film is exposed to a high-energy ray such as ultraviolet light, far ultraviolet light, an electron beam (EB) with an acceleration voltage of 1 to 150 kV, extreme ultraviolet light (EUV) with a wavelength of 3 to 15 nm, X-rays, soft X-rays, an excimer laser, gamma rays, or synchrotron radiation, either through a predetermined mask or directly, to form a desired pattern. In the pattern forming method of the present invention, it is particularly preferred that the exposure be carried out using extreme ultraviolet light having a wavelength of 3 to 15 nm or an electron beam having an acceleration voltage of 1 to 150 kV. The exposure dose is 1 to 300 mJ / cm 2 degree, especially 10-200mJ / cm 2 , or 1 to 500 μC / cm 2 degree, especially 5 to 400 μC / cm 2 is preferred.

[0034] [Step (iii)] Step (iii) is a step of post-exposure baking (PEB) of the resist film at 30 to 170° C. The PEB temperature is preferably 40 to 160° C., more preferably 50 to 150° C., and the treatment time is preferably 10 seconds to 30 minutes, more preferably 10 seconds to 20 minutes.

[0035] In the pattern forming method of the present invention, heating of the PEB after exposure can be carried out not only by a hot plate but also by infrared irradiation, laser irradiation, hot air blowing, or by placing the wafer in an atmosphere at the baking temperature.

[0036] Currently, most wafer heating methods use a hot plate. By placing a silicon wafer on the hot plate, the resist film is heated by heat transfer from the wafer. The temperature of the hot plate is controlled to adjust the temperature to which the resist film is heated.

[0037] [Step (iv)] In step (iv), the resist film is developed by dry etching after baking. The dry etching gas can be a mixed gas of oxygen, hydrogen, ammonia, fluorocarbon, chlorine, or bromine gas diluted with nitrogen, argon, helium, carbon dioxide, carbon monoxide, or sulfur dioxide.

[0038] [Resist materials] As described above, the resist film is formed using a resist material based on a polymer having a repeating unit in which a carboxyl group is substituted with an acid labile group having a phenol group.

[0039] The base polymer contained in the resist material used in the present invention is a polymer having either or both of the repeating units represented by the above-mentioned general formula (a1) and (a2) (these repeating units are also collectively referred to as repeating unit a). The repeating unit constituting the main chain of the base polymer has a carboxyl group, and the carboxyl group is protected (substituted) by an acid labile group. This acid labile group has a phenol group. A resist film is formed in a state in which the carboxyl group bonded to the main chain of the base polymer is protected by the acid labile group. The resist film is then exposed to light, whereby the carboxyl group is deprotected by the action of acid.

[0040] The group substituting the carboxyl group of the repeating unit, that is, the acid labile group having a phenol group, is represented by the following formula (a11) or (a22). [ka] (In the formula, R 1 and R 2 are each independently a linear, branched, or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to form a ring. 4 R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. 3 and R 5 are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each an integer of 1 to 3, and p and q are each an integer of 0 to 6.

[0041] Examples of monomers that provide the repeating unit represented by the above formula (a1) (hereinafter also referred to as repeating unit a1) include, but are not limited to, those shown below. A is the same as above.

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka] In the formula, the vinyl group on the aromatic ring may be replaced with an isopropenyl group.

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] Examples of monomers that provide the repeating unit represented by formula (a2) (hereinafter also referred to as repeating unit a2) include, but are not limited to, those shown below. A is the same as above.

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] [ka]

[0062] The present invention is characterized by having a repeating unit having an acid labile group of a phenolic hydroxyl group represented by the above general formula (a1) or (a2), but it is also possible to copolymerize a repeating unit having a conventional acid labile group without a phenolic hydroxyl group.

[0063] Examples of such conventional repeating units ax include those represented by the following formulae (ax1) and (ax2) (also referred to as repeating unit ax1 and repeating unit ax2, respectively; the same applies hereinafter). [ka] In formulas (ax1) and (ax2), R A are each independently a hydrogen atom or a methyl group. 1 is a single bond, a phenylene group, a naphthylene group, or a linking group having 1 to 12 carbon atoms and having an ester bond, an ether bond, or a lactone ring, and may have a halogen atom, a nitro group, a hydroxy group, an alkoxy group, an acyloxy group, or an alkoxycarbonyloxy group. 2 is a single bond, an ester bond or an amide bond. 11 and R 12 is an acid labile group. 13 R is a fluorine atom, a trifluoromethyl group, a cyano group, or an alkyl group having 1 to 6 carbon atoms. 14 is a single bond or a linear or branched alkanediyl group having 1 to 6 carbon atoms, some of the carbon atoms of which may be substituted with ether bonds or ester bonds. a is 1 or 2. b is an integer of 0 to 4.

[0064] Examples of monomers that provide the repeating unit ax1 include, but are not limited to, those shown below. A and R 11 is the same as above. [ka]

[0065] [ka]

[0066] Examples of monomers that provide the repeating unit ax2 include, but are not limited to, those shown below.A and R 12 is the same as above. [ka]

[0067] R 11 or R 12 The acid labile group represented by the formula (AL-1) may be selected from a variety of groups, and examples thereof include those represented by the following formulae (AL-1) to (AL-3). [ka] (In the formula, the dashed lines represent bonds.)

[0068] In formula (AL-1), c is an integer of 0 to 6. L1 is a tertiary hydrocarbyl group having 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trihydrocarbylsilyl group in which each hydrocarbyl group is a saturated hydrocarbyl group having 1 to 6 carbon atoms, a carbonyl group, or a saturated hydrocarbyl group having 4 to 20 carbon atoms containing an ether bond or an ester bond, or a group represented by formula (AL-3).

[0069] R L1The tertiary hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be branched or cyclic. Specific examples thereof include a tert-butyl group, a tert-pentyl group, a 1,1-diethylpropyl group, a 1-ethylcyclopentyl group, a 1-butylcyclopentyl group, a 1-ethylcyclohexyl group, a 1-butylcyclohexyl group, a 1-ethyl-2-cyclopentenyl group, a 1-ethyl-2-cyclohexenyl group, and a 2-methyl-2-adamantyl group. Examples of the trialkylsilyl group include a trimethylsilyl group, a triethylsilyl group, and a dimethyl-tert-butylsilyl group. The saturated hydrocarbyl group containing a carbonyl group, an ether bond, or an ester bond may be linear, branched, or cyclic, but is preferably cyclic. Specific examples thereof include a 3-oxocyclohexyl group, a 4-methyl-2-oxooxan-4-yl group, a 5-methyl-2-oxoxolan-5-yl group, a 2-tetrahydropyranyl group, and a 2-tetrahydrofuranyl group.

[0070] Examples of the acid labile group represented by formula (AL-1) include a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a tert-pentyloxycarbonyl group, a tert-pentyloxycarbonylmethyl group, a 1,1-diethylpropyloxycarbonyl group, a 1,1-diethylpropyloxycarbonylmethyl group, a 1-ethylcyclopentyloxycarbonyl group, a 1-ethylcyclopentyloxycarbonylmethyl group, a 1-ethyl-2-cyclopentenyloxycarbonyl group, a 1-ethyl-2-cyclopentenyloxycarbonylmethyl group, a 1-ethoxyethoxycarbonylmethyl group, a 2-tetrahydropyranyloxycarbonylmethyl group, and a 2-tetrahydrofuranyloxycarbonylmethyl group.

[0071] Further, examples of the acid labile group represented by formula (AL-1) include groups represented by the following formulae (AL-1)-1 to (AL-1)-10. [ka] (In the formula, the dashed lines represent bonds.)

[0072] In formulae (AL-1)-1 to (AL-1)-10, c is the same as defined above. L8 are each independently a saturated hydrocarbyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. L9 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. L10 is a saturated hydrocarbyl group having 2 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic.

[0073] In formula (AL-2), R L2 and R L3 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10. The saturated hydrocarbyl group may be linear, branched, or cyclic, and specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a cyclopentyl group, a cyclohexyl group, a 2-ethylhexyl group, and an n-octyl group.

[0074] In formula (AL-2), R L4 is a hydrocarbyl group having 1 to 18 carbon atoms, preferably 1 to 10, which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Examples of the hydrocarbyl group include saturated hydrocarbyl groups having 1 to 18 carbon atoms, and some of the hydrogen atoms may be substituted with hydroxy groups, alkoxy groups, oxo groups, amino groups, alkylamino groups, etc. Examples of such substituted saturated hydrocarbyl groups include those shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0075] R L2 and R L3 and R L2 and R L4 and, or R L3and R L4 may be bonded to each other to form a ring together with the carbon atom to which they are bonded, or together with the carbon atom and oxygen atom, and in this case, R L2 and R L3 , R L2 and R L4 , or R L3 and R L4 are each independently an alkanediyl group having 1 to 18 carbon atoms, preferably 1 to 10. The ring obtained by combining these groups preferably has 3 to 10 carbon atoms, more preferably 4 to 10 carbon atoms.

[0076] Among the acid labile groups represented by formula (AL-2), linear or branched ones include, but are not limited to, those represented by the following formulae (AL-2)-1 to (AL-2)-69, in which the dashed lines represent bonds. [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] Among the acid labile groups represented by formula (AL-2), examples of cyclic groups include a tetrahydrofuran-2-yl group, a 2-methyltetrahydrofuran-2-yl group, a tetrahydropyran-2-yl group, and a 2-methyltetrahydropyran-2-yl group.

[0081] Further, examples of the acid labile group include groups represented by the following formula (AL-2a) or (AL-2b): The base polymer may be inter- or intramolecularly crosslinked by the acid labile group. [ka] (In the formula, the dashed lines represent bonds.)

[0082] In formula (AL-2a) or (AL-2b), R L11 and R L12 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 8 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. L11 and R L12 may be bonded to each other to form a ring together with the carbon atoms to which they are attached, in which case R L11 and R L12 are each independently an alkanediyl group having 1 to 8 carbon atoms. L13 are each independently a saturated hydrocarbylene group having 1 to 10 carbon atoms. The saturated hydrocarbylene group may be linear, branched, or cyclic. d and e are each independently an integer of 0 to 10, preferably an integer of 0 to 5, and f is an integer of 1 to 7, preferably an integer of 1 to 3.

[0083] In formula (AL-2a) or (AL-2b), L A is an (f+1)-valent aliphatic saturated hydrocarbon group having 1 to 50 carbon atoms, an (f+1)-valent alicyclic saturated hydrocarbon group having 3 to 50 carbon atoms, an (f+1)-valent aromatic hydrocarbon group having 6 to 50 carbon atoms, or an (f+1)-valent heterocyclic group having 3 to 50 carbon atoms. In addition, some of the carbon atoms of these groups may be substituted with heteroatom-containing groups, and some of the hydrogen atoms bonded to carbon atoms of these groups may be substituted with hydroxy groups, carboxy groups, acyl groups, or fluorine atoms. A As L, saturated hydrocarbon groups such as saturated hydrocarbylene groups having 1 to 20 carbon atoms, trivalent saturated hydrocarbon groups, and tetravalent saturated hydrocarbon groups, and arylene groups having 6 to 30 carbon atoms are preferred. The saturated hydrocarbon groups may be linear, branched, or cyclic.B is -C(=O)-O-, -NH-C(=O)-O- or -NH-C(=O)-NH-.

[0084] Examples of the crosslinked acetal group represented by formula (AL-2a) or (AL-2b) include groups represented by the following formulae (AL-2)-70 to (AL-2)-77. [ka] (In the formula, the dashed lines represent bonds.)

[0085] 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 heteroatoms such as oxygen, sulfur, nitrogen, or fluorine atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, alkenyl groups having 2 to 20 carbon atoms, cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, and aryl groups having 6 to 10 carbon atoms. In addition, R L5 and R L6 and R L5 and R L7 and, or R L6 and R L7 may be bonded to each other to form an alicyclic ring having 3 to 20 carbon atoms together with the carbon atom to which they are bonded.

[0086] Examples of the group represented by formula (AL-3) include a tert-butyl group, a 1,1-diethylpropyl group, a 1-ethylnorbornyl group, a 1-methylcyclopentyl group, a 1-isopropylcyclopentyl group, a 1-ethylcyclopentyl group, a 1-methylcyclohexyl group, a 2-(2-methyl)adamantyl group, a 2-(2-ethyl)adamantyl group, and a tert-pentyl group.

[0087] Further, examples of the group represented by formula (AL-3) include groups represented by the following formulae (AL-3)-1 to (AL-3)-19. [ka] (In the formula, the dashed lines represent bonds.)

[0088] In formulas (AL-3)-1 to (AL-3)-19, R L14 are each independently a hydrogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 20 carbon atoms. L15 and R L17 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. L16 is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. The aryl group is preferably a phenyl group. R F is a fluorine atom or a trifluoromethyl group, and g is an integer of 1 to 5.

[0089] Further examples of the acid labile group include groups represented by the following formula (AL-3)-20 or (AL-3)-21: The acid labile group may cause intramolecular or intermolecular crosslinking of the polymer. [ka] (In the formula, the dashed lines represent bonds.)

[0090] In formulas (AL-3)-20 and (AL-3)-21, R L14 is the same as above. R L18 is a (h+1)-valent saturated hydrocarbylene group having 1 to 20 carbon atoms or a (h+1)-valent arylene group having 6 to 20 carbon atoms, and may contain a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. The saturated hydrocarbylene group may be linear, branched, or cyclic. h is an integer of 1 to 3.

[0091] Examples of the monomer that provides the repeating unit containing the acid labile group represented by formula (AL-3) include (meth)acrylate esters containing the exo structure represented by formula (AL-3)-22 below. [ka]

[0092] In formula (AL-3)-22, R A is the same as above. R Lc1 R is a saturated hydrocarbyl group having 1 to 8 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic. Lc2 ~R Lc11 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 15 carbon atoms which may contain a heteroatom. Examples of the heteroatom include an oxygen atom. Examples of the hydrocarbyl group include an alkyl group having 1 to 15 carbon atoms and an aryl group having 6 to 15 carbon atoms. R Lc2 and R Lc3 and R Lc4 and R Lc6 and R Lc4 and R Lc7 and R Lc5 and R Lc7 and R Lc5 and R Lc11 and R Lc6 and R Lc10 and R Lc8 and R Lc9 and, or R Lc9 and R Lc10 may be bonded to each other to form a ring together with the carbon atom to which they are bonded, and in this case, the group participating in the bond is a hydrocarbylene group having 1 to 15 carbon atoms which may contain a heteroatom. Lc2 and R Lc11 and R Lc8 and R Lc11 and, or R Lc4 and R Lc6 The term "a" means that adjacent carbon atoms may bond to each other without any intervening bond to form a double bond. This formula also represents an enantiomer.

[0093] Here, examples of monomers that provide the repeating unit represented by formula (AL-3)-22 include those described in JP-A-2000-327633. Specific examples include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0094] Examples of monomers that provide repeating units containing an acid labile group represented by formula (AL-3) include (meth)acrylic acid esters containing a furandiyl group, a tetrahydrofurandiyl group, or an oxanorbornanediyl group represented by formula (AL-3)-23 below. [ka]

[0095] In formula (AL-3)-23, R A is the same as above. R Lc12 and R Lc13 are each independently a hydrocarbyl group having 1 to 10 carbon atoms. Lc12 and R Lc13 may be bonded to each other to form an alicyclic ring together with the carbon atoms to which they are attached. Lc14 is a furandiyl group, a tetrahydrofurandiyl group, or an oxanorbornanediyl group. Lc15 is a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hydrogen atom or a heteroatom. The hydrocarbyl group may be linear, branched, or cyclic. Specific examples thereof include saturated hydrocarbyl groups having 1 to 10 carbon atoms.

[0096] Examples of monomers that provide the repeating unit represented by formula (AL-3)-23 include, but are not limited to, those shown below. A is the same as above, Ac is an acetyl group, and Me is a methyl group. [ka]

[0097] [ka]

[0098] The base polymer preferably further contains a repeating unit b having at least one acid generating moiety selected from the repeating units represented by the following formulas (b1) to (b5). [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. B are each independently a hydrogen atom or Z 6 may be bonded to form a ring. 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 -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 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, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O- or -Z 31 -O-. Z 31 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, a nitro group, a cyano group, an ester bond, an ether bond, a urethane bond, a fluorine atom, an iodine atom, or a bromine atom. Z 4 is a single bond, a methylene group, or an ethylene group. 5represents a single bond, a methylene group, an ethylene group, a phenylene group, a methylphenylene group, a dimethylphenylene 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. Z 51 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a methylphenylene group, a dimethylphenylene 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. 6 is a single bond, a phenylene group, a naphthylene ring, an ester bond or an amide bond. 7A represents a single bond or a divalent organic group having 1 to 24 carbon atoms, and may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. 7B is a monovalent organic group having 1 to 10 carbon atoms, which may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. 8 is a single bond, an ether bond, an ester bond, a thioether bond, or an alkanediyl group having 1 to 6 carbon atoms. 9 is a trivalent organic group having 1 to 12 carbon atoms, and may have at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine with the carbon atom to which they are attached to form a carbonyl group. 21 and R 22 R are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23is a saturated hydrocarbyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a fluorine atom, an iodine atom, a trifluoromethoxy group, a difluoromethoxy group, a cyano group, or a nitro group. Ring R is a (d+2)-valent aromatic hydrocarbon group having 6 to 10 carbon atoms. d is an integer of 0 to 5. X - is a non-nucleophilic counterion. M + is a sulfonium cation or an iodonium cation.

[0099] Examples of monomers that provide the repeating unit b1 include, but are not limited to, the following: A is the same as above. [ka]

[0100] In formula (b1), X - 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, imidate 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.

[0101] Further examples of the non-nucleophilic counter ion include a sulfonate ion represented by the following formula (b1-1) in which the α-position is substituted with a fluorine atom, and a sulfonate ion represented by the following formula (b1-2) in which the α-position is substituted with a fluorine atom and the β-position is substituted with a trifluoromethyl group. [ka]

[0102] In formula (b1-1), R 31 is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, and may contain an ether bond, an ester bond, a carbonyl group, a lactone ring, or a fluorine atom. The alkyl group and alkenyl group may be linear, branched, or cyclic.

[0103] In formula (b1-2), R 32 is a hydrogen atom, an alkyl group having 1 to 30 carbon atoms, an acyl group having 2 to 30 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aryloxy group having 6 to 20 carbon atoms, and may contain an ether bond, an ester bond, a carbonyl group, or a lactone ring. The alkyl group, acyl group, and alkenyl group may be linear, branched, or cyclic.

[0104] As the non-nucleophilic counter ion, an anion containing bromine or iodine represented by the following formula (b1-3) can also be used.

[0105] [ka]

[0106] Specific examples of the anion shown in (b1-3) above include the following.

[0107] [ka]

[0108]

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[0109]

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[0110]

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[0111]

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[0112]

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[0113]

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[0114]

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[0115]

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[0116]

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[0117]

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[0118]

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[0119]

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[0120]

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[0121]

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[0122]

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[0123]

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[0124]

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[0125]

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[0126]

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[0127]

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[0128]

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[0129] [ka] In the above, X BI is a bromine atom or an iodine atom.

[0130] Examples of the anion of the monomer that gives the repeating unit b2 include, but are not limited to, those shown below. A is the same as above. [ka]

[0131] [ka]

[0132] [ka]

[0133] [ka]

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] [ka]

[0138] [ka]

[0139] [ka]

[0140] [ka]

[0141] [ka]

[0142] Examples of the anion of the monomer that gives the repeating unit b3 include, but are not limited to, those shown below. A is the same as above. [ka]

[0143] [ka]

[0144] Specific examples of the anion of the repeating units b4 and b5 include, but are not limited to, the following: BI is an iodine atom or a bromine atom. [ka]

[0145] [ka]

[0146] [ka]

[0147]

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[0148]

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[0149]

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[0150]

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[0151]

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[0152]

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[0153]

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[0154]

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[0155]

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[0156]

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[0157]

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[0158]

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[0159]

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[0160]

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[0161]

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[0162]

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[0163]

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[0164]

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[0165]

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[0166]

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[0167]

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[0168]

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[0169]

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[0170]

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[0171]

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[0172]

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[0173]

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[0174]

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[0175]

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[0176]

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[0177]

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[0178]

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[0179]

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[0180]

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[0181]

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[0182]

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[0183]

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[0184]

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[0185]

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[0186]

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[0187]

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[0188]

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[0189]

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[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] The base polymer contains Z in the formulas (b2) to (b5) as the repeating unit b having an acid generating moiety. 3 , Z 7A , Z 7B or M + However, it is preferable to use a repeating unit containing one or more iodine atoms, as the use of such a repeating unit containing an iodine atom enables more suitable pattern formation. The base polymer may further contain a repeating unit c having an adhesive group selected from a hydroxy group, a carboxy group, a lactone ring, a carbonate group, a thiocarbonate group, a carbonyl group, a cyclic acetal group, an ether bond, an ester bond, a sulfonate ester bond, a cyano group, an amide group, -OC(=O)-S-, and -OC(=O)-NH-.

[0194] Examples of monomers that provide the repeating unit c include, but are not limited to, those shown below. A is the same as above. [ka]

[0195] [ka]

[0196] [ka]

[0197] [ka]

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201] [ka]

[0202] The base polymer may further contain a repeating unit d that does not contain an amino group but contains an iodine atom. Examples of monomers that provide the repeating unit d include, but are not limited to, the following. In the following formula, R A is the same as above. [ka]

[0203] [ka]

[0204] The base polymer may contain a repeating unit e other than the repeating units described above. Examples of the repeating unit e include those derived from styrene, vinyl naphthalene, indene, acenaphthylene, coumarin, coumarone, and the like.

[0205] In the base polymer, the content ratios (mole fractions) of the repeating units a1, a2, b1, b2, b3, b4, b5, c, d, and e with respect to all the repeating units are preferably 0 ≦ a1 ≦ 1.0, 0 ≦ a2 ≦ 1.0, 0 < a1 + a2 ≦ 1.0, 0 ≦ b1 ≦ 0.5, 0 ≦ b2 ≦ 0.5, 0 ≦ b3 ≦ 0.5, 0 ≦ b4 ≦ 0.5, 0 ≦ b5 ≦ 0.5, 0 ≦ b1 + b2 + b3 + b4 + b5 ≦ 0.5, 0 ≦ c ≦ 0.8, 0 ≦ d ≦ 0.5, and 0 ≦ e ≦ 0.5. However, a1 + a2 + b1 + b2 + b3 + b4 + b5 + c + d + e = 1.0. In this specification, the description based on the endpoints of the numerical range includes all the values included in that range.

[0206] To synthesize the base polymer, for example, monomers that provide the repeating units described above may be heated in an organic solvent with a radical polymerization initiator added thereto to perform polymerization.

[0207] Examples of the organic solvent used during polymerization include toluene, benzene, tetrahydrofuran (THF), diethyl ether, dioxane, propylene glycol monomethyl ether, γ-butyrolactone, and mixed solvents thereof. 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, and the like. 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.

[0208] When a monomer containing a hydroxy group is copolymerized, the hydroxy group may be substituted with an acetal group that is easily deprotected by an acid, such as an ethoxyethoxy group, during polymerization, and then deprotected with a weak acid and water after polymerization. Alternatively, the hydroxy group may be substituted with an acetyl group, a formyl group, a pivaloyl group, or the like, and then subjected to alkaline hydrolysis after polymerization.

[0209] When copolymerizing hydroxystyrene or hydroxyvinylnaphthalene, acetoxystyrene or acetoxyvinylnaphthalene may be used instead of hydroxystyrene or hydroxyvinylnaphthalene, and after polymerization, the acetoxy group may be deprotected by the alkaline hydrolysis to give hydroxystyrene or hydroxyvinylnaphthalene.

[0210] The base that can be used in alkaline hydrolysis includes aqueous ammonia, triethylamine, etc. The reaction temperature is preferably −20 to 100° C., more preferably 0 to 60° C. The reaction time is preferably 0.2 to 100 hours, more preferably 0.5 to 20 hours.

[0211] The base polymer preferably has a weight-average molecular weight (Mw) of 1,000 to 500,000, more preferably 2,000 to 30,000, as measured by gel permeation chromatography (GPC) using THF as a solvent, relative to polystyrene standards. An Mw of 1,000 or greater provides a resist material with good heat resistance, while an Mw of 500,000 or less provides sufficient alkali solubility, making it less likely for tailing to occur after pattern formation. The number-average molecular weight (Mn) can also be determined by GPC.

[0212] Furthermore, if the base polymer has a broad molecular weight distribution (Mw / Mn), the presence of low-molecular-weight and high-molecular-weight polymers may result in the appearance of foreign matter on the pattern after exposure, or the pattern shape may be deteriorated. As the pattern rule becomes finer, the effects of Mw and Mw / Mn tend to become greater. Therefore, in order to obtain a resist material that is suitable for use with 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.

[0213] To obtain narrow-dispersity polymers, living radical polymerization can be used in addition to conventional radical polymerization, including nitroxide-mediated radical polymerization (NMP), atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer (RAFT) polymerization.

[0214] The base polymer may contain two or more polymers with different composition ratios, Mw, or Mw / Mn. Alternatively, a polymer containing the repeating unit a and a polymer not containing the repeating unit a may be blended.

[0215] [Acid generator] In the present invention, instead of using a polymer having an acid generating moiety incorporated therein (polymer-bound acid generator) as the acid generator, an acid generator can be incorporated into the resist material, or these can be combined. The acid generation mode can be adjusted by adding an acid generator separately from the base polymer (externally added acid generator), by using a polymer having an acid generating moiety that also functions as an acid generator incorporated therein (internal added acid generator), or by combining these. By incorporating such an acid generator—an externally added acid generator, an internally added acid generator, or a combination thereof—into a resist material, the acid-generating function of the resist material can be optimized.

[0216] The externally added acid generator is not particularly limited, and may be any substance that generates an acid in response to an external stimulus such as heat or light. Examples include compounds (photoacid generators) that generate an acid in response to actinic rays or radiation. The photoacid generator component may be any compound that generates an acid upon exposure to high-energy rays, but acid generators that generate sulfonic acid, imide acid, or methide acid are preferred. Specific examples of suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate-type acid generators. Specific examples of the acid generators include those described in paragraphs

[0122] to

[0142] of JP 2008-111103 A, JP 2018-5224 A, and JP 2018-25789 A. When the resist composition of the present invention contains such an externally added acid generator, the content thereof is preferably from 0 to 200 parts by mass, and more preferably from 0.1 to 100 parts by mass, per 100 parts by mass of the base polymer.

[0217] [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 components described above and the components described below. Specific examples of the organic solvent include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone, as described in paragraphs

[0144] and

[0145] of JP-A No. 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 monomethyl ether. 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.

[0218] In the resist composition 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, per 100 parts by mass of the base polymer. The organic solvents may be used singly or in combination of two or more.

[0219] [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.

[0220] Examples of the quencher include conventional basic compounds. Specific 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. Particularly preferred are the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP 2008-111103 A, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonate ester bond, and compounds having a carbamate bond described in Japanese Patent No. 3790649 A. Addition of such basic compounds can, for example, further suppress the diffusion rate of acid in the resist film or correct the shape.

[0221] Further, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of sulfonic acids, carboxylic acids, or fluorinated alkoxides that are not fluorinated at the α-position, as described in JP 2008-158339 A. Sulfonic acids, imide acids, or methide acids that are fluorinated at the α-position are necessary for deprotecting the acid labile group of a carboxylic acid ester, and salt exchange with the onium salt releases sulfonic acids, carboxylic acids, or fluorinated alcohols that are not fluorinated at the α-position. Sulfonic acids, carboxylic acids, and fluorinated alcohols that are not fluorinated at the α-position do not undergo a deprotection reaction, and therefore function as quenchers.

[0222] Specific examples of such quenchers include a compound represented by the following formula (4) (onium salt of sulfonic acid not fluorinated at the α-position), a compound represented by the following formula (5) (onium salt of carboxylic acid), and a compound represented by the following formula (6) (onium salt of alkoxide). [ka]

[0223] In formula (4), R 101 represents a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group.

[0224] R 101 The hydrocarbyl group having 1 to 40 carbon atoms 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 40 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, and an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, and a tricyclo[5.2.1.0] 2,6 ]Cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as a decyl group, an adamantyl group, and an adamantylmethyl group; alkenyl groups having 2 to 40 carbon atoms such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 40 carbon atoms such as a cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl groups (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, Examples of aryl groups include aryl groups having 6 to 40 carbon atoms such as arylphenyl groups (e.g., 2,4-n-butylphenyl group, 4-n-butylphenyl group), di- or trialkylphenyl groups (e.g., 2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group), alkylnaphthyl groups (e.g., methylnaphthyl group, ethylnaphthyl group), and dialkylnaphthyl groups (e.g., dimethylnaphthyl group, diethylnaphthyl group); and aralkyl groups having 7 to 40 carbon atoms such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0225] Furthermore, 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 some of the -CH- groups of the hydrocarbyl group 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 hydrocarbyl group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Specific examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; and aryloxoalkyl groups such as a 2-aryl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0226] In formula (5), R 102 R is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a heteroatom. 102 Specific examples of the hydrocarbyl group represented by R 101 Examples of the hydrocarbyl group include the same groups as those exemplified above. Other specific examples include fluorinated 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 fluorinated aryl groups such as a pentafluorophenyl group and a 4-trifluoromethylphenyl group.

[0227] In formula (6), R 103is a saturated hydrocarbyl group having 1 to 8 carbon atoms and at least three fluorine atoms, or an aryl group having 6 to 10 carbon atoms and at least three fluorine atoms, which may contain a nitro group.

[0228] In equations (4), (5) and (6), 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. Specific examples of the sulfonium cation include M + Examples of the sulfonium cation represented by the formula: include the same as those exemplified above.

[0229] As the quencher, a sulfonium salt of an iodinated benzene ring-containing carboxylic acid represented by the following formula (7) can also be suitably used. [ka]

[0230] In formula (7), x is an integer of 1 to 5. y is an integer of 0 to 3. z is an integer of 1 to 3.

[0231] In formula (7), R 111 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 111A )-C(=O)-R 111B or -N(R 111A )-C(=O)-OR 111B R 111A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 111Bis a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When y and / or z is 2 or more, each R 111 may be the same or different from each other.

[0232] In formula (7), L 1 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. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic.

[0233] In formula (7), R 112 , R 113 and R 114 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 4 ~R 8 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0234] Specific examples of the compound represented by formula (7) include those described in JP-A-2017-219836 and JP-A-2021-91666.

[0235] Another example of the quencher is the polymer-type quencher described in JP 2008-239918 A. This quencher enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. The polymer-type quencher also has the effect of preventing pattern thinning and rounding of the pattern top when a protective film for immersion lithography is applied.

[0236] Furthermore, betaine-type sulfonium salts described in Japanese Patent No. 6848776 and Japanese Patent Application Laid-Open No. 2020-37544, fluorine-free methide acids described in Japanese Patent Application Laid-Open No. 2020-55797, sulfonium salts of sulfonamides described in Japanese Patent Application Laid-Open No. 5807552, sulfonium salts of sulfonamides containing iodine atoms described in Japanese Patent Application Laid-Open No. 2019-211751, and acid generators that generate phenols, halogens, and carbonic acid can also be used as quenchers.

[0237] When the resist composition of the present invention contains the quencher, the content thereof is preferably 0 to 5 parts by mass, more preferably 0 to 4 parts by mass, relative to 100 parts by mass of the base polymer. The quencher may be used alone or in combination of two or more types.

[0238] [Other ingredients] In addition to the above-mentioned components, surfactants, dissolution inhibitors, crosslinking agents, water repellency improvers, acetylene alcohols, etc. may also be contained.

[0239] Specific examples of the surfactant include those described in paragraphs

[0165] and

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

[0240] When the resist material of the present invention is a positive resist, the incorporation of a dissolution inhibitor can further increase the difference in dissolution rate between exposed and unexposed areas, thereby further improving resolution. Specific examples of the dissolution inhibitor include compounds having a molecular weight of preferably 100 to 1000, more preferably 150 to 800, containing two or more phenolic hydroxy groups in the molecule, in which the hydrogen atoms of the phenolic hydroxy groups have been substituted with acid labile groups at a rate of 0 to 100 mol % overall, and compounds containing carboxy groups in the molecule in which the hydrogen atoms of the carboxy groups have been substituted with acid labile groups at an average rate of 50 to 100 mol % overall. Specific examples include compounds in which the hydrogen atoms of the hydroxyl groups or carboxyl groups of bisphenol A, trisphenol, phenolphthalein, cresol novolak, naphthalenecarboxylic acid, adamantanecarboxylic acid, and cholic acid have been substituted with acid labile groups, as described, for example, in paragraphs

[0155] to

[0178] of JP 2008-122932 A.

[0241] When the resist composition of the present invention is a positive resist composition and contains the dissolution inhibitor, the content thereof is preferably 0 to 50 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the base polymer. The dissolution inhibitor may be used alone or in combination of two or more types.

[0242] On the other hand, when the resist material of the present invention is negative-working, a negative pattern can be obtained by adding a crosslinking agent to reduce the dissolution rate of the exposed area. Specific 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, all 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 polymer side chains. Hydroxy-containing compounds may also be used as crosslinking agents.

[0243] Specific examples of the epoxy compound include tris(2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

[0244] Specific 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.

[0245] Specific examples of the guanamine compound include tetramethylolguanamine, tetramethoxymethylguanamine, a compound of tetramethylolguanamine in which 1 to 4 methylol groups are methoxymethylated, or a mixture thereof; tetramethoxyethylguanamine, tetraacyloxyguanamine, a compound of tetramethylolguanamine in which 1 to 4 methylol groups are acyloxymethylated, or a mixture thereof; and the like.

[0246] Specific examples of the glycoluril compound include tetramethylol glycoluril, tetramethoxy glycoluril, tetramethoxymethyl glycoluril, a compound in which 1 to 4 methylol groups of tetramethylol glycoluril have been methoxymethylated or a mixture thereof, a compound in which 1 to 4 methylol groups of tetramethylol glycoluril have been acyloxymethylated or a mixture thereof, etc. Specific examples of the urea compound include tetramethylol urea, tetramethoxymethyl urea, a compound in which 1 to 4 methylol groups of tetramethylol urea have been methoxymethylated or a mixture thereof, tetramethoxyethyl urea, etc.

[0247] Specific examples of the isocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and cyclohexane diisocyanate.

[0248] Specific examples of the azide compound include 1,1'-biphenyl-4,4'-bisazide, 4,4'-methylidenebisazide, and 4,4'-oxybisazide.

[0249] Specific examples of the compound 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.

[0250] When the resist composition of the present invention is a negative resist composition 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, per 100 parts by mass of the base polymer. The crosslinking agents may be used alone or in combination of two or more.

[0251] The water repellency improver improves the water repellency of the resist film surface and can be used in immersion lithography without a top coat. Preferred examples of the water repellency improver include polymers containing fluorinated alkyl groups and polymers containing a 1,1,1,3,3,3-hexafluoro-2-propanol residue with a specific structure, and examples thereof are described in JP-A Nos. 2007-297590 and 2008-111103. The water repellency improver must be soluble in an alkaline developer or an organic solvent developer. The water repellency improver having the specific 1,1,1,3,3,3-hexafluoro-2-propanol residue described above has good solubility in the developer. As a water repellency improver, a polymer containing a repeating unit containing an amino group or an amine salt is highly effective in preventing the evaporation of acid during PEB and preventing poor opening 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, relative to 100 parts by mass of the base polymer. The water repellency improver may be used alone or in combination of two or more.

[0252] Specific examples of 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 the acetylene alcohols, the content thereof is preferably 0 to 5 parts by mass per 100 parts by mass of the base polymer. The acetylene alcohols may be used alone or in combination of two or more.

[0253] When the resist material of the present invention is used in the manufacture of various integrated circuits, known lithography techniques can be applied as needed.

[0254] For example, the resist material of the present invention is applied to a substrate for integrated circuit manufacturing (Si, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective coating, etc.) or a substrate for mask circuit manufacturing (Cr, CrO, CrON, MoSi2, SiO2, etc.) by a suitable coating method such as spin coating, roll coating, flow coating, dip coating, spray coating, doctor coating, etc., to 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.

[0255] When ultraviolet rays, far ultraviolet rays, EUV, X-rays, soft X-rays, excimer laser light, gamma rays, synchrotron radiation, or the like is used as the high-energy rays, the exposure dose is preferably 1 to 200 mJ / cm, 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 300 μC / cm 2 approximately, more preferably 0.5 to 200 μC / cm 2 As described above, the resist material of the present invention is particularly suitable for fine patterning using high-energy rays such as 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. Specifically, examples of the pattern forming method include a pattern forming method in which exposure is performed using extreme ultraviolet light with a wavelength of 3 to 15 nm, and a pattern forming method in which exposure is performed using an electron beam with an acceleration voltage of 1 to 150 kV.

[0256] After exposure, PEB can be performed on a hot plate or in an oven, preferably at 30 to 150°C for 10 seconds to 30 minutes, more preferably at 50 to 120°C for 30 seconds to 20 minutes. The deprotection reaction during PEB deprotects the acid labile groups having phenolic groups, evaporates the deprotecting components from the film, and produces a polymer having carboxyl groups in the resist film.

[0257] As described above, dry etching is performed after PEB to remove the exposed areas and open the spaces. For dry etching, a gas containing oxygen, hydrogen, ammonia, or the like, and a diluting gas containing nitrogen, helium, argon, carbon dioxide, or carbon monoxide is preferably used. Fluorocarbon, chlorine, bromine, or iodine-based gases can also be mixed.

[0258] Regarding the detailed conditions for dry etching, the conditions described in Patent Document 3 can be used.

[0259] The developed hole or trench pattern can also be shrunk using thermal flow, RELACS, or DSA. A shrink agent is applied to the hole pattern, and the diffusion of an acid catalyst from the resist film during baking causes crosslinking of the shrink agent on the surface of the resist film, resulting in adhesion of the shrink agent 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. Excess shrink agent is removed, and the hole pattern is shrunk.

[0260] The pattern formation method of the present invention is characterized by combining the use of a base polymer having one or both of the repeating units represented by the above general formula (a1) and (a2) with the formation of a pattern by development using dry etching. In the present invention, a resist film is formed using a resist material containing the above-described base polymer in which the carboxyl group bonded to the polymer main chain is protected by an acid labile group, and the resist film is exposed to light, heated, and then developed by dry etching to form a pattern. In the present invention, a resist material based on a polymer having a repeating unit in which a carboxyl group is protected with an acid labile group having a phenol group is used. As a result, the unexposed portion has a phenol group, and the exposed portion generates a carboxyl group by deprotection. When this is dry etched, radicals generated in the etching chamber are absorbed by the phenol, slowing the etching rate of the unexposed portion, while the exposed portion etch rate increases with decarboxylation and main chain decomposition. This increases the etching rate selectivity between the exposed and unexposed portions without relying on film shrinkage in the exposed portion, allowing for the formation of fine patterns with a high aspect ratio. Development by dry etching does not cause pattern collapse due to stress generated during spin drying in solution development, and therefore allows for the formation of patterns with higher aspect ratios and higher resolution. [Example]

[0261] The present invention will be specifically explained below by showing synthesis examples, preparation examples, working examples and comparative examples, but the present invention is not limited to the following examples.

[0262] [Synthesis example] Synthesis of base resin Each monomer was combined and copolymerized in THF, crystallized in methanol, and then repeatedly washed with hexane, isolated, and dried to synthesize the base resins (polymers 1 to 12, comparative polymers 1 and 2) with the following compositions. The resulting base resins had the following compositions: 1 Mw and Mw / Mn were confirmed by H-NMR and GPC (solvent: THF, standard: polystyrene).

[0263] [ka]

[0264] [ka]

[0265] [ka]

[0266] [ka]

[0267] [ka]

[0268] [Preparation Examples 1 to 12, Comparative Preparation Examples 1 and 2] Preparation of resist materials A solution of the components shown in Table 1 dissolved in a solvent containing 50 ppm of Omnova surfactant Polyfox 636 was filtered through a 0.2 μm filter to prepare a positive resist material.

[0269] In Table 1, the components are as follows: Acid generator: PAG-1, PAG-2 [ka]

[0270] Quencher: Quencher 1 [ka]

[0271] Organic solvent: PGMEA (propylene glycol monomethyl ether acetate) DAA (diacetone alcohol)

[0272] [Table 1]

[0273] [Examples 1-1 to 1-12, Comparative Examples 1-1 and 1-2] KrF exposure and dry etching evaluation Each resist material (R-1 to R-7, CR-1, CR-2) was spin-coated onto a Si substrate coated with a 60-nm-thick anti-reflective coating (DUV-42) manufactured by Nissan Chemical Industries, Ltd., and pre-baked at 105°C for 60 seconds using a hot plate to produce a 140-nm-thick resist film. A 90-nm line-and-space pattern was exposed to the resist using an ASML KrF excimer scanner (XT860N, NA 0.8, dipole illumination, 6% halftone phase-shift mask), and PEB was performed on a hot plate at the temperature listed in Table 2 for 60 seconds.

[0274] After the PEB treatment, the wafer was etched using a dry etching apparatus Terius manufactured by Tokyo Electron Limited under the following conditions. Chamber pressure 12.0Pa RF power 600W Bias power 50W Stage temperature: 25℃ O2 gas flow rate 20sccm N2 gas flow rate: 400sccm Time 30sec

[0275] The resist film and anti-reflection film in the exposed areas were thinned by dry etching until the Si substrate surface was revealed.

[0276] The exposure dose at which 90 nm lines and spaces were formed at a 1:1 ratio using a Hitachi High-Technologies Corporation CG-6300 measuring SEM was used, and the resist sensitivity was determined. The wafer was then cut, and the cross section of the 90 nm line and space pattern was observed using a Hitachi High-Technologies Corporation S-4100 electron microscope.

[0277] The results are shown in Table 2.

[0278] [Table 2]

[0279] [Examples 2-1 to 2-12, Comparative Examples 2-1 and 2-2] KrF exposure and film thickness evaluation Each resist material (R-1 to R-7, CR-1, CR-2) was spin-coated onto a Si substrate coated with a 60-nm-thick anti-reflective coating (DUV-42) manufactured by Nissan Chemical Industries, Ltd., and pre-baked at 105°C for 60 seconds using a hot plate to produce a 140-nm-thick resist film. This was then subjected to open-frame exposure using an ASML KrF excimer scanner (XT860N, NA 0.8, normal illumination), followed by PEB for 60 seconds on a hot plate at the temperature listed in Table 3. An exposure dose of 0 mJ / cm was measured using an optical film thickness meter. 2 and 100 mJ / cm 2 The film thickness was measured at an exposure dose of 100 mJ / cm 2 The exposure dose is 0 mJ / cm 2 The shrinkage rate of the film was calculated by dividing the film thickness by the film thickness.

[0280] The results are shown in Table 3.

[0281] [Table 3]

[0282] The results shown in Tables 2 and 3 demonstrate that the use of a resist material based on a polymer copolymerized with an acid-labile group having a phenolic hydroxyl group enables pattern formation by dry etching development according to the present invention. In the case of the resist material CR-1 based on a polymer copolymerized with an acid-labile group not having a phenolic hydroxyl group (Comparative Example 1-1), although the amount of film shrinkage was not significant (Comparative Example 2-1), the film disappeared not only in the exposed areas but also in the unexposed areas. In the case of the resist of Comparative Example 1-2, the amount of film shrinkage in the spaced areas of the exposed areas after PEB was large (Comparative Example 2-2), and although the spaced areas were opened after dry etching, the pattern deformation due to the large amount of film shrinkage during PEB resulted in a triangular cross-sectional shape. Development by dry etching eliminates pattern collapse due to stress generated during spin drying in solution development, enabling the formation of patterns with higher aspect ratios and higher resolution.

[0283] The present specification includes the following aspects. [1]: A pattern formation method comprising: preparing a resist material containing a polymer in which a carboxyl group bonded to a polymer main chain is protected by an acid labile group; forming a resist film using the resist material; exposing and heating the resist film; and developing the resist film by dry etching to form a pattern, The pattern forming method is characterized in that the polymer used has one or both of repeating units represented by the following general formulas (a1) and (a2): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 and R 2 are each independently a linear, branched, or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to form a ring. 4 R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. 3 and R 5 are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each integers of 1 to 3, and p and q are each integers of 0 to 6. X 1 is a single bond, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group. [2]: The pattern forming method according to [1], wherein the resist material further contains an acid generator. [3]: The pattern formation method according to [1] or [2], characterized in that a resist material containing a polymer having a repeating unit b having an acid generating moiety in addition to the repeating unit is used. [4]: The pattern forming method according to [3], wherein the repeating unit b having the acid generating moiety is a repeating unit selected from the repeating units represented by the following formulas (b1) to (b5): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. B are each independently a hydrogen atom or Z 6 may be bonded to form a ring. 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 -OZ 11 -, -C(=O)-OZ 11 - or -C(=O)-NH-Z 11 -It is. Z 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, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 is a single bond or an ester bond. 3 is a single bond, -Z 31 -C(=O)-O- or -Z 31 -O-. Z 31 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, a nitro group, a cyano group, an ester bond, an ether bond, a urethane bond, a fluorine atom, an iodine atom, or a bromine atom. Z 4 is a single bond, a methylene group, or an ethylene group. 5represents a single bond, a methylene group, an ethylene group, a phenylene group, a methylphenylene group, a dimethylphenylene 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. Z 51 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a methylphenylene group, a dimethylphenylene 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. 6 is a single bond, a phenylene group, a naphthylene ring, an ester bond or an amide bond. 7A represents a single bond or a divalent organic group having 1 to 24 carbon atoms, and may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. 7B is a monovalent organic group having 1 to 10 carbon atoms, which may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. 8 is a single bond, an ether bond, an ester bond, a thioether bond, or an alkanediyl group having 1 to 6 carbon atoms. 9 is a trivalent organic group having 1 to 12 carbon atoms, and may have at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. 1 ~Rf 4 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a trifluoromethyl group. 1 and Rf 2 may combine with the carbon atom to which they are attached to form a carbonyl group. 21 and R 22 R are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 23is a saturated hydrocarbyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a fluorine atom, an iodine atom, a trifluoromethoxy group, a difluoromethoxy group, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring R is a (d+2)-valent aromatic hydrocarbon group having 6 to 10 carbon atoms. d is an integer of 0 to 5. X - is a non-nucleophilic counterion. M + is a sulfonium cation or an iodonium cation. [5]: As the repeating unit b having the acid generating moiety, Z in the above formula 3 , Z 7A , Z 7B or M + The pattern forming method according to [4], wherein a repeating unit containing one or more iodine atoms is used. [6]: The pattern forming method according to any one of [1] to [5], wherein the exposure is carried out with extreme ultraviolet light having a wavelength of 3 to 15 nm. [7]: The pattern forming method according to any one of [1] to [5], wherein the exposure is carried out with an electron beam having an acceleration voltage of 1 to 150 kV. [8]: A resist material used for pattern formation by dry etching, characterized in that it contains a polymer having one or both of repeating units represented by the following general formulas (a1) and (a2): [ka] (In the formula, R A are each independently a hydrogen atom or a methyl group. 1 and R 2 are each independently a linear, branched, or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R 1 and R 2 may be bonded to form a ring. 4 R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. 3and R 5 are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each integers of 1 to 3, and p and q are each integers of 0 to 6. X 1 is a single bond, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group.

[0284] The present invention is not limited to the above-described embodiments, which are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that provides similar effects is included within the technical scope of the present invention.

Claims

1. A pattern forming method comprising: preparing a resist material containing a polymer in which a carboxyl group bonded to a polymer main chain is protected by an acid labile group; forming a resist film using the resist material; exposing and heating the resist film; and developing the resist film by dry etching to form a pattern, The pattern forming method is characterized in that the polymer used has one or both of repeating units represented by the following general formulas (a1) and (a2): 【Chemical 1】 (In the formula, R Ａ are each independently a hydrogen atom or a methyl group. １ and R ２ are each independently a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R １ and R ２ may be bonded to form a ring. ４ R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. ３ and R ５ are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each integers of 1 to 3, and p and q are each integers of 0 to 6. X １ is a single bond, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group.

2. 2. The pattern forming method according to claim 1, wherein the resist material further contains an acid generator.

3. 2. The pattern formation method according to claim 1, wherein a resist material containing a polymer having a repeating unit b having an acid generating moiety in addition to the repeating unit is used.

4. 4. The pattern formation method according to claim 3, wherein the repeating unit b having the acid generating moiety is a repeating unit selected from the repeating units represented by the following formulas (b1) to (b5): 【Chemistry 2】 (In the formula, R Ａ are each independently a hydrogen atom or a methyl group. Ｂ are each independently a hydrogen atom or Z ６ may be bonded to form a ring. 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. Z 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. ２ is a single bond or an ester bond. ３ is a single bond, -Z ３１ -C(=O)-O- or -Z ３１ -O-. Z ３１ represents 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, a nitro group, a cyano group, an ester bond, an ether bond, a urethane bond, a fluorine atom, an iodine atom, or a bromine atom. ４ is a single bond, a methylene group, or an ethylene group. ５ represents a single bond, a methylene group, an ethylene group, a phenylene group, a methylphenylene group, a dimethylphenylene 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. Z ５１ represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a methylphenylene group, a dimethylphenylene 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. ６ is a single bond, a phenylene group, a naphthylene ring, an ester bond or an amide bond. ７Ａ represents a single bond or a divalent organic group having 1 to 24 carbon atoms, and may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. ７Ｂ is a monovalent organic group having 1 to 10 carbon atoms, which may have at least one atom selected from a halogen atom, an oxygen atom, a nitrogen atom, and a sulfur atom. ８ is a single bond, an ether bond, an ester bond, a thioether bond, or an alkanediyl group having 1 to 6 carbon atoms. ９ is a trivalent organic group having 1 to 12 carbon atoms, and may have at least one atom selected from an oxygen atom, a nitrogen atom, and a sulfur atom. １ ~Rf ４ are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a trifluoromethyl group. １ and Rf ２ may combine with the carbon atom to which they are attached to form a carbonyl group. ２１ and R ２２ R are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. ２３ is a saturated hydrocarbyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, a fluorine atom, an iodine atom, a trifluoromethoxy group, a difluoromethoxy group, a cyano group, or a nitro group. Ring R is a (d+2)-valent aromatic hydrocarbon group having 6 to 10 carbon atoms. d is an integer of 0 to 5. X － is a non-nucleophilic counterion. ＋ is a sulfonium cation or an iodonium cation.

5. The repeating unit b having the acid generating moiety is Z in the formula ３ , Z ７Ａ , Z ７Ｂ or M ＋ 5. The pattern formation method according to claim 4, wherein the repeating unit contains one or more iodine atoms.

6. 2. The pattern forming method according to claim 1, wherein the exposure is carried out with extreme ultraviolet light having a wavelength of 3 to 15 nm.

7. 2. The pattern forming method according to claim 1, wherein the exposure is carried out with an electron beam having an acceleration voltage of 1 to 150 kV.

8. A resist material used for pattern formation by dry etching, comprising a polymer having one or both of repeating units represented by the following general formulas (a1) and (a2): 【Chemistry 3】 (In the formula, R Ａ are each independently a hydrogen atom or a methyl group. １ and R ２ are each independently a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms, which may have a double bond or a triple bond, or an aryl group having 6 to 10 carbon atoms; R １ and R ２ may be bonded to form a ring. ４ R is a hydrogen atom or a linear, branched or cyclic aliphatic hydrocarbon group having 1 to 14 carbon atoms which may have a double bond or a triple bond. ３ and R ５ are each independently a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxy group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkoxycarbonyl group having 1 to 6 carbon atoms, a linear, branched, or cyclic alkanoyl group having 1 to 6 carbon atoms, a halogen atom, a cyano group, a trifluoromethyl group, a trifluoromethoxy group, or a nitro group. Ring A is an aryl group having 6 to 16 carbon atoms, ring B is a 4- to 8-membered ring which may have a double bond, and ring C is an aryl group having 6 to 16 carbon atoms. m and n are each integers of 1 to 3, and p and q are each integers of 0 to 6. X １ is a single bond, or a linking group having 1 to 12 carbon atoms and containing at least one selected from an ester bond, a lactone ring, a phenylene group, and a naphthylene group.

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