Polymer, chemically amplified positive resist composition, resist pattern forming method, and mask blank

Abstract

To provide: a polymer capable of forming a resist film that enables formation of a pattern having extremely high isolated space resolution, small LER, and excellent rectangularity, and suppressing effects of development loading and residue defects, as well as, having etching resistance and suppressing pattern collapse in the produced resist pattern; a chemically amplified positive resist composition using the polymer; a resist pattern formation method using the chemically amplified positive resist composition; and a mask blank using the chemically amplified positive resist composition.SOLUTION: Provided is a polymer which comprises a structural unit including an aromatic hydroxyl group bonded to a main chain, wherein the aromatic hydroxyl group is protected by an acid-labile group represented by the following formula (ALU-1) and is deprotected by an action of an acid to become alkali-soluble.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polymer having a specific structure, a chemically amplified positive resist composition using the same, a resist pattern forming method, and a mask blank.

Background Art

[0002] In recent years, with the increasing integration of integrated circuits, finer pattern formation has been required. In the processing of patterns with a size of 0.2 μm or less, chemically amplified resist compositions mainly catalyzed by acids are mainly used. At this time, high-energy rays such as ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), and electron beams (EB) are used as exposure light sources. In particular, EB lithography, which is used as an ultrafine processing technology, is also indispensable as a method for processing photomask blanks when manufacturing photomasks for semiconductor production.

[0003] Generally, in electron beam (EB) lithography, drawing with EB is performed without using a mask. In the case of a positive type, fine-area EB is sequentially irradiated on the portions other than the areas where the resist film is to be left, and in the case of a negative type, fine-area EB is sequentially irradiated on the areas where the resist film is to be left. That is, since it sweeps over all the finely divided regions of the processing surface, it takes more time than single exposure using a photomask. To avoid reducing throughput, a highly sensitive resist film is required. In the processing of photomask blanks, which is a particularly important application, there are those with surface materials such as chromium compound films including chromium oxide formed on the photomask substrate, which are likely to affect the pattern shape of chemically amplified resist films. To maintain high resolution and the shape after etching, regardless of the type of substrate, keeping the pattern profile of the resist film rectangular is regarded as one of the important performances. Also, having a small line edge roughness (LER) is regarded as one of the important performances. In recent years, in order to achieve miniaturization, a multi-beam mask writing (MBMW) drawing process may be used for processing mask blanks. In this case, a low-sensitivity resist (high-dose region) that is advantageous for roughness is used for the resist, and the optimization of the resist composition in this high-dose region has also been spotlighted.

[0004] Regarding the control of sensitivity and pattern profile, various improvements have been made depending on the selection and combination of materials used in the resist composition, process conditions, etc. One of such improvements is the suppression of acid diffusion, which significantly affects the resolution of the resist film. In photomask processing, it is required that the shape of the obtained resist pattern does not change depending on the time from exposure to heating. A major cause of the time-dependent change in the resist pattern shape is the diffusion of the acid generated by exposure. This problem of acid diffusion has been studied extensively because it significantly affects sensitivity and resolution not only in photomask processing but also in general resist compositions.

[0005] Patent Document 1 and Patent Document 2 describe examples of suppressing acid diffusion and reducing LER by swelling the acid generated from an acid generator. However, in such acid generators, the suppression of acid diffusion is still insufficient, so the development of an acid generator with smaller acid diffusion has been desired.

[0006] In addition, Patent Document 3 describes an example of controlling acid diffusion by introducing a repeating unit having a sulfonium structure that generates sulfonic acid upon exposure into a polymer used in a resist composition. The method of suppressing acid diffusion by introducing a repeating unit that generates an acid upon such exposure into a base polymer is effective as a method for obtaining a pattern with a small LER. However, a base polymer containing a repeating unit that generates an acid upon such exposure may have a problem in solubility in an organic solvent depending on the structure and introduction rate of the unit.

[0007] A polymer having a large amount of an aromatic skeleton having an acidic side chain, for example, polyhydroxystyrene, is useful as a base polymer for a resist composition for KrF lithography, but since it exhibits a large absorption to light in the vicinity of a wavelength of 200 nm, it has not been used as a base polymer for a resist composition for ArF lithography. However, it is an important material in terms of obtaining high etching resistance as a resist composition for EB lithography or a resist composition for EUV lithography, which is a promising technology for forming a pattern smaller than the processing limit by ArF excimer laser light.

[0008] As a base polymer for a positive resist composition for EB lithography or a resist composition for EUV lithography, a material that solubilizes in an alkaline developer by deprotecting an acid-labile group that masks the acidic functional group of the phenol side chain of the base polymer using the acid generated by irradiating a photoacid generator with high-energy rays as a catalyst is mainly used. As the acid-labile group, in addition to a tertiary alkyl group and a tert-butoxycarbonyl group, an acetal group has been used as an acid-labile group having a relatively small activation energy (Patent Document 4, Patent Document 5, Patent Document 6, Patent Document 7, Patent Document 8).

[0009] However, although the acetal group has the advantage of obtaining a highly sensitive resist film, especially in the multi-beam mask writing (MBMW) drawing process in electron beam (EB) lithography for fabricating advanced masks with a line width of 10 nm or less, since it is drawn in a thin film region with a resist film thickness of 100 nm or less and a high-dose region with a large irradiation energy, if the reactivity and structure of the acetal are bulky, a deprotection reaction occurs even in the unexposed portion of the resist film, and residues remain even in the exposed portion, particularly causing problems such as deterioration of isolated space resolution and line edge roughness (LER), which are important for positive resists, and generation of defects.

[0010] Also, in the development process of photomask manufacturing, it is known that a phenomenon called development loading occurs, where there is a difference in the pattern size finish between the dense region and the sparse region on the photomask. That is, due to development loading, a non-uniform distribution occurs in the pattern size finish according to the surrounding pattern distribution. The factors include differences in the elimination reaction during acid generation due to the energy difference of the EB, and differences in the dissolution rate of the alkaline developer in the dense and sparse pattern drawing areas. As one of the improvements, Patent Document 9 discloses a method of adjusting the incident dose amount in the EB drawing apparatus to irradiate the EB and draw a pattern on the photomask so as to correct the development loading. However, the conventional correction method did not sufficiently consider the phenomenon of development loading for correction. Therefore, the conventional correction method had poor correction accuracy for development loading. To solve this problem, methods for improving the drawing method when drawing a resist film and the development method after patterning, described in Patent Documents 10 and 11, have been developed, but they are insufficient for uniformly distributing dense and fine patterns in the advanced generation, and there has been a demand for improvement of a resist composition that can achieve high resolution, reduction of development loading, and reduction of residue defects even in the advanced generation.

Prior Art Documents

Patent Documents

[0011] Patent Document 1 Japanese Patent Application Laid-Open No. 2009-053518 Patent Document 2 Japanese Patent Application Laid-Open No. 2010-100604 Patent Document 3 Japanese Patent Application Laid-Open No. 2011-022564 Patent Document 4 Japanese Patent No. 3981830 Patent Document 5 Japanese Patent No. 5385017 Patent Document 6 International Publication No. 2019 / 167419 Patent Document 7 Japanese Patent No. 6987873 Patent Document 8 Japanese Patent No. 5696254 Patent Document 9 Japanese Patent Application Laid-Open No. 2007-150243 Patent Document 10 Japanese Patent No. 5443548 Patent Document 11 Japanese Patent No. 6281244 Summary of the Invention Problems to be Solved by the Invention

[0012] The present invention has been made to solve the above problems, has extremely high isolated space resolution, a small LER, excellent rectangularity, suppresses the influence of development loading and residue defects, and has etching resistance excellent in It is an object of the present invention to provide a polymer capable of forming a resist film capable of forming a pattern that suppresses pattern collapse of a produced resist pattern, a chemically amplified positive resist composition using the same, a resist pattern forming method using the chemically amplified positive resist composition, and a mask blank using the chemically amplified positive resist composition Means for Solving the Problems

[0013] In order to solve the above problems, the present invention provides a polymer in which the aromatic hydroxyl group in the structural unit containing an aromatic hydroxyl group bonded to the main chain is protected by an acid-labile group represented by the following formula (ALU-1) and is deprotected by the action of an acid to become alkali-soluble. [Chemical formula] (In formula (ALU-1), R L1 ~R L3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms and do not contain an aromatic cyclic structure. Among R L1 ~R L3 , any two of them may be bonded to each other to form a cyclic structure together with the carbon atom to which they are bonded. R L4 is a hydrogen atom, a halogen atom, a nitro group, or a hydrocarbyl group having 1 to 6 carbon atoms which may contain a hetero atom. n1 is an integer of 0 or 1. n2 is an integer of 0 to 5 when n1 = 0, and an integer of 0 to 7 when n1 = 1. The dashed line represents the bond with the oxygen atom of the aromatic hydroxyl group of the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer.)

[0014] Such a polymer has extremely high isolated space resolution, a small LER, excellent rectangularity, suppresses the influence of development loading and residue defects, and has etching resistance excellent in It becomes a polymer capable of forming a resist film capable of suppressing pattern collapse of the produced resist pattern.

[0015] Further, in the present invention, it is preferable that the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer is a repeating unit represented by the following formula (A1). [Chemical formula] (In formula (A1), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 1is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. X 2 is any one of a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond and a carbamate bond. R B is a halogen atom, or a linear, branched or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. n1 is the same as above. n3 is an integer of 0 to 4 when n1 = 0, and an integer of 0 to 6 when n1 = 1. n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≤ 5, and when n1 = 1, n3 + n4 ≤ 7. The dashed line represents a bond with the above formula (ALU-1).)

[0016] With such a polymer, the above effects can be surely achieved.

[0017] Further, in the present invention, it is preferable that the polymer further contains a repeating unit containing a phenolic hydroxy group represented by the following formula (A2). [Chemical formula] (In formula (A2), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. X 2 is any one of a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond and a carbamate bond. R Bis a linear, branched or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a hetero atom. n1 is the same as described above. n3 is an integer of 0 to 4 when n1 = 0, and an integer of 0 to 6 when n1 = 1. n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≤ 5, and when n1 = 1, n3 + n4 ≤ 7.)

[0018] For such a polymer, an appropriate dissolution rate in an alkaline developer can be ensured.

[0019] At this time, it is preferable that the repeating unit containing a phenolic hydroxy group is a repeating unit represented by the following formula (A2-1).

Chemical formula

[0020] For such a polymer, the above effects can be more effectively exerted.

[0021] Further, in the present invention, it is preferable that the polymer further contains one or more repeating units represented by any of the following formulas (B1) to (B3).

Chemical formula

[0022] For such a polymer, in addition to the etching resistance of the aromatic ring, the EB irradiation resistance during etching and pattern inspection can be enhanced by adding a ring structure to the main chain.)

[0023] In the present invention, it is preferable that the polymer further contains a repeating unit represented by the following formula (A3-1) and / or the following formula (A3-2). [Chemical formula] (In formula (A3-1), R A are, independently of each other, a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. b1 is 0 or 1. b2 is an integer of 0 to 2. b3 is an integer satisfying 0 ≦ b3 ≦ 5 + 2b2 - b4. b4 is an integer of 1 to 3. b5 is 0 or 1. R’ 12 is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. A 3is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH2- of the saturated hydrocarbylene group may be substituted with -O-. X is an acid-labile group when b4 is 1, and is a hydrogen atom or an acid-labile group when b4 is 2 or more, and at least one of them is an acid-labile group.)

Chemical formula

[0024] For such a polymer, since the dissolution rate of the exposed portion becomes high, good performance can be given to the line width variation in development loading.)

[0025] Further, in the present invention, it is preferable that the polymer further contains one or more repeating units represented by any of the following formulas (C1) to (C8).

Chemical formula

[0026] For such a polymer, acid diffusion can be moderately suppressed, and a pattern with reduced LER can be obtained.

[0027] Further, the present invention provides a chemically amplified positive resist composition containing the polymer described above.

[0028] For such a chemically amplified positive resist composition, it has extremely high isolated space resolution, small LER, excellent rectangularity, suppresses the influence of development loading and residue defects, and etching resistance excellent in A chemically amplified positive resist composition using a polymer capable of forming a resist film capable of forming a pattern that suppresses pattern collapse of the produced resist pattern is obtained.

[0029] Further, in the present invention, it is preferably further contained in an organic solvent.

[0030] For such a chemically amplified positive resist composition, workability is excellent.

[0031] Further, in the present invention, it is preferably further contained a photoacid generator in which the acid strength (pKa) of the conjugate acid of the anion is -2.0 or more.

[0032] In the case of such a chemically amplified positive resist composition, the deprotection reaction of the acid-labile group of the polymer is catalyzed, resulting in good resolution.

[0033] At this time, as the photoacid generator, it is preferably one containing the anion structure of the photoacid generator represented by the following formula (M-1). [Chemical formula] (In formula (M-1), m is 0 or 1. p is an integer from 1 to 3. q is an integer from 1 to 5. r is an integer from 0 to 3. L 1 is a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. L 2 is an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. X 4 When p is 1, it is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms. When p is 2 or 3, it is a (p + 1)-valent hydrocarbon group having 1 to 20 carbon atoms. The hydrocarbylene group and the (p + 1)-valent hydrocarbon group may contain at least one 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. Rf 1 and Rf 2 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. R 21 is a hydroxy group, a carboxy group, 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, a fluorine atom, a chlorine atom, a bromine atom, an amino group, -N(R 1A )-C(=O)-R 1B or -N(R 1A )-C(=O)-O-R 1B and R 1A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 1Bis a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 22 is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, and part or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and part or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from saturated hydrocarbyl groups having 1 to 20 carbon atoms, saturated hydrocarbyloxy groups having 1 to 20 carbon atoms, aryl groups having 6 to 14 carbon atoms, halogen atoms, and hydroxy groups.)

[0034] Such a chemically amplified positive resist composition can exhibit the above effects more effectively.

[0035] In addition, in the present invention, it is preferably further included a quencher.

[0036] Such a chemically amplified positive resist composition can further suppress the acid diffusion rate in the resist film and correct the shape.

[0037] In addition, in the present invention, it is preferably further included a fluorine atom-containing polymer containing at least one selected from the repeating unit represented by the following formula (D1), the repeating unit represented by the following formula (D2), the repeating unit represented by the following formula (D3), and the repeating unit represented by the following formula (D4). [Chemical formula] (In the formula, R B are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108is, independently, a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms or an acid-labile group, R 103 , R 106 , R 107 and R 108 when being a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. m’ is an integer of 1 to 3. Z 1 is a hydrocarbon group having (m’ + 1) valences with 1 to 20 carbon atoms or a fluorinated hydrocarbon group having (m’ + 1) valences with 1 to 20 carbon atoms. )

[0038] For such a chemically amplified positive resist composition, it is possible to achieve high contrast, shield chemical flare of acid in high-energy ray irradiation and mixing of acid from an antistatic film material in the process of coating the antistatic film material on the resist film, and suppress unexpected unnecessary pattern deterioration.

[0039] At this time, it is preferable that the fluorine atom-containing polymer further contains at least one selected from the repeating unit represented by the following formula (D5) and the repeating unit represented by the following formula (D6). [Chemical formula] (In the formula, R C is, independently, a hydrogen atom or a methyl group. R 109 is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms in which a group containing a hetero atom may be interposed between carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms in which a group containing a hetero atom may be interposed between carbon-carbon bonds. R 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a part of -CH2- constituting the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. x is an integer of 1 to 3. y is an integer satisfying 0 ≦ y ≦ 5 + 2z - x. z is 0 or 1. Z2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 -. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. Z 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * is a bond to a carbon atom of the main chain.)

[0040] For such a chemically amplified positive resist composition, the above effects can be more effectively exerted.

[0041] In the present invention, it is preferable that the dissolution rate of the polymer in an alkaline developer is 10 nm / min or less.

[0042] For such a chemically amplified positive resist composition, the pattern does not collapse and a fine pattern can be formed.

[0043] In the present invention, it is preferable that the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less.

[0044] For such a chemically amplified positive resist composition, the pattern does not collapse and a fine pattern can be formed.

[0045] In the present invention, it is preferable that the dissolution rate of the exposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 50 nm / sec or more.

[0046] For such a chemically amplified positive resist composition, even if there is a pattern layout difference in the dense and sparse patterns, it can be uniformly dissolved in an alkaline developer, and the line width variation can be reduced.

[0047] In addition, the present invention provides a resist pattern forming method including a step of forming a resist film on a substrate using the chemically amplified positive resist composition described above, a step of irradiating the resist film with a high-energy ray to form a pattern, and a step of developing the resist film irradiated with the pattern using an alkaline developer.

[0048] Such a resist pattern forming method has extremely high isolated space resolution, small LER, excellent rectangularity, suppresses the influence of development loading and residue defects, and has etching resistance excellent in It becomes possible to form a pattern that suppresses pattern collapse of the produced resist pattern.

[0049] In addition, in the present invention, it is preferable to use KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm as the high-energy ray.

[0050] Such a high-energy ray can be used in the resist pattern forming method of the present invention.

[0051] In addition, in the present invention, it is preferable to use a substrate whose outermost surface is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin.

[0052] The resist pattern forming method of the present invention is particularly useful for forming a pattern on a substrate having a surface made of a material that is likely to cause pattern peeling or pattern collapse.

[0053] At this time, it is preferable to use a transmissive or reflective mask blank as the substrate.

[0054] The resist pattern forming method of the present invention can use the substrate as described above.

[0055] Further, the present invention provides a transmissive or reflective mask blank coated with the chemically amplified positive resist composition described above.

[0056] Such a mask blank has extremely high isolated space resolution, small LER, excellent rectangularity, suppresses the effects of development loading and residue defects, and has etching resistance excellent in It becomes a mask blank using a chemically amplified positive resist composition using a polymer capable of forming a resist film capable of forming a pattern that suppresses pattern collapse of the produced resist pattern.

Advantages of the Invention

[0057] The chemically amplified positive resist composition using the polymer of the present invention has high resolution, small LER, can form a pattern with excellent rectangularity in the shape after exposure and suppress the influence of residue defects, and is suitable as a resist composition for forming a resist film sensitive to an electron beam used for processing such as semiconductors and photomask blanks. Further, the pattern formation method using the chemically amplified positive resist composition of the present invention has high resolution, has etching resistance, and can form a pattern with reduced LER and a pattern that suppresses the influence of residue defects, so it can be suitably used for microfabrication techniques, particularly EUV lithography and EB lithography.

Modes for Carrying Out the Invention

[0058] As described above, it has extremely high isolated space resolution, small LER, excellent rectangularity, suppresses the effects of development loading and residue defects, and has etching resistance excellent in There has been a demand for the development of a polymer capable of forming a resist film capable of forming a pattern that suppresses pattern collapse of the produced resist pattern, a chemically amplified positive resist composition using the same, a resist pattern formation method using the chemically amplified positive resist composition, and a mask blank using the chemically amplified positive resist composition.

[0059] As a result of intensive studies to achieve the above object, the present inventors have found that by using a resist composition containing a polymer having an acetal-type acid-labile group with a specific structure, even in a high-dose region, good isolated space resolution, pattern shape, and LER are exhibited, and a pattern in which the effects of development loading and residue defects are suppressed can be obtained, and thus the present invention has been accomplished.

[0060] That is, the present invention relates to a polymer in which the aromatic hydroxyl group in the structural unit containing an aromatic hydroxyl group bonded to the main chain is protected by an acid-labile group represented by the following formula (ALU-1) and is deprotected by the action of an acid to become alkali-soluble. [Chemical formula] (In formula (ALU-1), R L1 ~R L3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms and do not contain an aromatic cyclic structure. Among R L1 ~R L3 , any two of them may be bonded to each other to form a cyclic structure together with the carbon atom to which they are bonded. R L4 is a hydrogen atom, a halogen atom, a nitro group, or a hydrocarbyl group having 1 to 6 carbon atoms which may contain a hetero atom. n1 is an integer of 0 or 1. n2 is an integer of 0 to 5 when n1 = 0 and an integer of 0 to 7 when n1 = 1. The broken line represents the bond with the oxygen atom of the aromatic hydroxyl group of the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer.)

[0061] Hereinafter, the present invention will be described in detail. In the following description, depending on the structure represented by the chemical formula, there may be asymmetric carbons and enantiomers and diastereomers may exist. In that case, those isomers are represented by one formula. Those isomers may be used alone or as a mixture.

[0062] [Polymer] In the polymer of the present invention, the aromatic hydroxyl group in the structural unit containing an aromatic hydroxyl group bonded to the main chain is protected by an acid-labile group represented by the following formula (ALU-1), and is deprotected by the action of an acid to become alkali-soluble. [Chemical formula] (In formula (ALU-1), R L1 ~R L3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms and not containing an aromatic cyclic structure. R L1 ~R L3 Among them, any two of them may be bonded to each other to form a cyclic structure together with the carbon atom to which they are bonded. R L4 is a hydrogen atom, a halogen atom, a nitro group, or a hydrocarbyl group having 1 to 6 carbon atoms which may contain a hetero atom. n1 is an integer of 0 or 1. n2 is an integer of 0 to 5 when n1 = 0, and an integer of 0 to 7 when n1 = 1. The dashed line represents the bond with the oxygen atom of the aromatic hydroxyl group of the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer.)

[0063] In formula (ALU-1), R L1 ~R L3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms and not containing an aromatic cyclic structure. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 6 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group; alkenyl groups having 2 to 6 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 6 carbon atoms such as cyclohexenyl group, etc., but are not limited thereto.

[0064] R L1 ~R L3Among them, any two of them may be bonded to each other to form a cyclic structure together with the carbon atoms to which they are bonded. Specific examples of the ring structure include, but are not limited to, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, etc.

[0065] R L1 ~R L3 are appropriately selected according to the design of the sensitivity to the decomposable group with respect to the acid. For example, if the design is to decompose with a strong acid while ensuring relatively high stability, a hydrogen atom is selected. If the design is to achieve high sensitivity to pH changes and suppress residue defects using relatively high reactivity, a linear alkyl group is selected. Examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group. When R L1 ~R L3 forms a ring, a cyclopentyl group and a cyclohexyl group can be mentioned, and more preferably a methyl group having optimal acid elimination performance.

[0066] As the acetal structure composed of formula (ALU-1), the carbon between R L1 ~R L3 is preferably secondary from the viewpoints of the stability of the polymer and the reactivity with an acid. If the carbon between R L1 ~R L3 is secondary, the reactivity is moderate and the stability is good compared to the case where the carbon between R L1 ~R L3 is primary, and the reactivity is good and the reaction contrast is improved compared to the case where the carbon between R L1 ~R L3 is tertiary.

[0067] R L4 is a hydrocarbyl group having 1 to 6 carbon atoms which may contain a hydrogen atom, a halogen atom, a nitro group, or a hetero atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0068] Specific examples of the hydrocarbyl group include the above R L1 ~R L3Examples similar to those listed above can be cited, but are not limited thereto. Further, 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 -CH2- constituting the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, an alkoxy group, a thioalkoxy group, a fluorine-containing alkyl group, a fluorine-containing alkoxy group, a fluorine-containing thioalkoxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, or the like.

[0069] In formula (ALU-1), n1 is an integer of 0 or 1. When n1 = 0, it represents a benzene ring, and when n1 = 1, it represents a naphthalene ring. From the viewpoints of ease of raw material procurement and solubility of the decomposition product after deprotection in an alkaline developer, a benzene ring with n1 = 0 is preferred.

[0070] In formula (ALU-1), n2 is an integer from 0 to 5 when n1 = 0, and an integer from 0 to 7 when n1 = 1.

[0071] Specific examples of formula (ALU-1) include, but are not limited to, the following. The dashed line represents the bond with the oxygen atom of the aromatic hydroxy group of the unit containing the aromatic hydroxy group bonded to the main chain of the polymer.

Chemical formula

[0072]

Chemical formula

[0073]

Chemical formula

[0074] [Chemical formula]

[0075] As factors for obtaining high resolution due to the aromatic acetal type acid-labile group contained in the polymer of the present invention, in the exposed area, the aromatic alcohol component generated after the elimination reaction has high solubility in the alkaline developer, and the residue component after development is reduced. On the other hand, in the unexposed area, the aromatic rings in the polymer main chain and the aromatic rings in the aromatic acetal type acid-labile group are regularly arranged due to the stacking effect, improving the rigidity, and the resistance to collapse against the developer is manifested. Therefore, the contrast between the exposed area and the unexposed area is improved. Due to these synergistic effects, it works advantageously for mask processing in the sub-10 nm generation.

[0076] The unit containing an aromatic hydroxyl group bonded to the main chain of the polymer, which is modified by the above (ALU-1), is preferably the repeating unit A1 represented by the following formula (A1). [Chemical formula] (In formula (A1), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to the carbon atom of the main chain. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. X 2 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. R Bis a linear, branched or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a hetero atom. n1 is the same as described above. n3 is an integer of 0 to 4 when n1 = 0, and an integer of 0 to 6 when n1 = 1. n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≤ 5, and when n1 = 1, n3 + n4 ≤ 7. The dashed line represents the bond with the formula (ALU-1).)

[0077] In the formula (A1), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0078] In the formula (A1), X 1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond with a carbon atom of the main chain.

[0079] In the formula (A1), A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched or cyclic. Specific examples thereof include alkane diyl groups having 1 to 10 carbon atoms such as a methylene group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms such as a cyclopropane diyl group, a cyclobutane diyl group, a cyclopentane diyl group, a cyclohexane diyl group; and groups obtained by combining these.

[0080] In the formula (A1), X 2 is any one of a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond and a carbamate bond. Among these, a single bond, an ether bond or an ester bond is preferable, and a single bond or an ester bond is more preferable.

[0081] In the formula (A1), R B is a halogen atom or a linear, branched or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group; alkenyl groups having 2 to 20 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclohexenyl group; aryl groups having 6 to 20 carbon atoms such as phenyl group, naphthyl group; aralkyl groups having 7 to 20 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group; groups obtained by combining these, etc. Among these, an aryl group is preferable. Further, 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, a halogen atom, and a part of -CH2- constituting the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, and as a result, it may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride, a haloalkyl group, etc.

[0082] In the formula (A1), n1 is an integer of 0 or 1.

[0083] In the formula (A1), when n1 = 0, n3 is an integer of 0 to 4, and when n1 = 1, n3 is an integer of 0 to 6.

[0084] In the formula (A1), n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≤ 5, and when n1 = 1, n3 + n4 ≤ 7.

[0085] Specific examples of formula (A1) include, but are not limited to, the following. The dashed line represents the bond with the formula (ALU-1). [Chemical formula]

[0086] [Chemical formula]

[0087] [Chemical formula]

[0088] [Chemical formula]

[0089] [Chemical formula]

[0090] Methods for protecting the polymer with an acetal-type acid-labile group after polymerization include methods using vinyl ether and an acid catalyst, methods using an acetalizing agent having a haloalkoxy group together with a base, etc. Any of these methods can be used here.

[0091] For example, in the case of the method using vinyl ether and an acid catalyst, examples of the acid catalyst used during the reaction include methanesulfonic acid, trifluoroacetic acid, oxalic acid, pyridine methanesulfonate, etc. The reaction temperature is preferably 5°C to 30°C, and the reaction time is 0.2 to 10 hours, preferably 0.5 to 6 hours. Li

[0092] ​Also, as a method of using an acetalizing agent having a haloalkoxy group together with a base, the method is to drop an acetalizing agent having a haloalkoxy group in the presence of a basic compound such as triethylamine. The reaction temperature at this time is -20 to 50 °C, and the reaction time is 0.2 to 10 hours, preferably 0.5 to 6 hours.

[0093] However, in the method of using an acetalizing agent having a haloalkoxy group together with a base, a highly corrosive strong acid such as hydrochloric acid is generated, which may corrode a metal production kettle or piping, and there is a risk that metal components that are defect factors in semiconductor products may be contaminated. Particularly in the advanced generations, the metal impurities in the raw materials used in the resist composition are required to be 10 ppb or less. Therefore, preferably, it is a method using vinyl ether and an acid catalyst.

[0094] The repeating unit protected by the above acetal-type acid-labile group is preferably introduced in the range of 10 to 40 mol%, more preferably 10 to 35 mol%, and still more preferably 20 to 30 mol% in all the repeating units of the polymer contained in the chemically amplified positive resist composition described later.

[0095] As the design of the above chemically amplified positive resist composition, in addition to the polymer having an acid-labile group protected by the acetal group shown in the present invention, it can also be mixed with a polymer having a tertiary alkyl group or an acid-labile group protected by a tert-butoxycarbonyl group as known and well-known. However, in order to exhibit the effects of the present invention, the proportion of the polymer having an acid-labile group protected by the acetal group shown in the present invention in all the polymers contained in the chemically amplified positive resist composition is preferably 30% or more.

[0096] Since the acetal-type acid-labile group contained in the polymer of the present invention also has the effect of suppressing the influence of backscattering during electron beam lithography, the pattern shape exhibits rectangular performance without becoming an inverse taper in a sensitivity region of 50 μC or more, preferably 80 μC or more, and more preferably 100 μC or more.

[0097] The polymer of the present invention preferably contains, in addition to the repeating unit A1 in which the aromatic hydroxyl group is protected by (ALU-1), a repeating unit represented by the repeating unit A2 containing a phenolic hydroxyl group.

[0098] The repeating unit A2 is represented by the following formula (A2). For a polymer having such a repeating unit, an appropriate dissolution rate in an alkaline developer can be ensured.

Chemical formula

[0099] In formula (A2), R A , X 1 , X 2 , A 1 , R B , n1, n3, n4 are the same as above.

[0100] X 1 and A 1When both are single bonds, preferable examples of the repeating unit A2 include units derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, and the like. Among these, more preferably, it is a repeating unit represented by the following formula (A2-1) or the like. [Chemical formula] (In formula (A2-1), R A is the same as described above. b’ is an integer from 1 to 3.)

[0101] X 1 When it is other than a single bond, preferable examples of the repeating unit A2 include those in which the dashed line part in the above formula (A1) becomes a hydrogen atom, but are not limited thereto.

[0102] The repeating unit A2 is preferably introduced in the range of 30 to 90 mol% in all the repeating units of the polymer, and more preferably in the range of 40 to 85 mol%. However, when it contains at least one of the repeating unit B1 represented by the formula (B1) and the repeating unit B2 represented by the formula (B2) that gives high etching resistance depending on the polymer described later, and the unit has a phenolic hydroxy group as a substituent, it is preferably within the above range including that ratio. The repeating unit A2 may be used alone or in combination of two or more.

[0103] The polymer preferably further contains one or more selected from the repeating unit B1 represented by the following formula (B1), the repeating unit B2 represented by the following formula (B2), and the repeating unit B3 represented by the following formula (B3). [Chemical formula] (In the formula, R A are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. b and c are each independently an integer from 0 to 4. d is an integer from 0 to 5. e is an integer from 0 to 2. X3 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. R 11 and R 12 are each independently a hydroxy group, a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom. R 13 is an acetyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group or a cyano group, and when e is 1 or 2, it may also be a hydroxy group.)

[0104] In formulas (B1) and (B2), b and c are each independently an integer of 0 to 4.

[0105] In formulas (B1) and (B2), R 11 and R 12 are each independently a hydroxy group, a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom. The saturated hydrocarbyl group, saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group may be linear, branched or cyclic. When b is 2 or more, each R 11 may be the same as or different from each other. When c is 2 or more, each R 12 may be the same as or different from each other.

[0106] In formula (B3), R A is the same as described above. d is an integer from 0 to 5. e is an integer from 0 to 2.

[0107] In formula (B3), R 13 is an acetyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group or a cyano group, and when e is 1 or 2, it may also be a hydroxy group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbyloxyhydrocarbyl group and saturated hydrocarbylthiohydrocarbyl group may be linear, branched or cyclic. When d is 2 or more, each R 13 may be the same as or different from each other.

[0108] In formula (B3), X 3 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom of the main chain.

[0109] In formula (B3), A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched or cyclic, and specific examples thereof include A in formula (A1) 1 which are the same as those exemplified in the description of.

[0110] When the repeating units B1 to B3 are used, in addition to the etching resistance of the aromatic ring, an effect of enhancing the EB irradiation resistance during etching and pattern inspection can be obtained due to the addition of a ring structure to the main chain.

[0111] In order to obtain the effect of improving the etching resistance, the repeating units B1 to B3 are preferably introduced in an amount of 5 mol% or more in all the repeating units of the polymer. Further, the repeating units B1 to B3 are preferably introduced in an amount of 25 mol% or less, more preferably 20 mol% or less, in all the repeating units constituting the polymer. When there is no functional group or when the functional group is other than a hydroxy group, an introduction amount of 25 mol% or less is preferable because there is no risk of developing defects. The repeating units B1 to B3 may be used alone or in combination of two or more.

[0112] In all the repeating units of the polymer, the content of at least one selected from the repeating unit A2 and the repeating units B1 to B3 is preferably 50 mol% or more, more preferably 60 mol% or more.

[0113] The polymer of the present invention preferably further contains a repeating unit represented by the following formula (A3-1) and / or the following formula (A3-2). The polymer may be a polymer containing the repeating unit A1, the repeating unit A2, the repeating unit A3-1 represented by the following formula (A3-1), and the repeating unit A3-2 represented by the following formula (A3-2), or may be a polymer containing the repeating unit A1 and the repeating unit A2, a polymer containing the repeating unit A1 and the repeating unit A3-1, and / or a polymer containing the repeating unit A1 and the repeating unit A3-2.

Chemical formula

[0114] In formula (A3-1), R A is the same as described above. b1 is 0 or 1. b2 is an integer of 0 to 2, and represents a benzene skeleton when 0, a naphthalene skeleton when 1, and an anthracene skeleton when 2, respectively. b3 is an integer satisfying 0 ≦ b3 ≦ 5 + 2b2 - b4. b4 is an integer of 1 to 3. b5 is 0 or 1. When b2 is 0, preferably, b3 is an integer of 0 to 3, and b4 is an integer of 1 to 3. When b2 is 1 or 2, preferably, b3 is an integer of 0 to 4, and b4 is an integer of 1 to 3.

[0115] In formula (A3-1), R’ 12 is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. The saturated hydrocarbyl moiety of the saturated hydrocarbyl group, saturated hydrocarbyloxy group and saturated hydrocarbylcarbonyloxy group may be linear, branched or cyclic. Specific examples thereof include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group; cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group; groups obtained by combining these, etc. If the number of carbon atoms is below the upper limit, the solubility in an alkaline developer is good. When b3 is 2 or more, each R’12 may be the same as or different from each other.

[0116] In formula (A3-1), A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and -CH2- of the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic. Specific examples thereof include alkane diyl groups such as methylene group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, and structural isomers thereof; cyclic saturated hydrocarbylene groups such as cyclopropane diyl group, cyclobutane diyl group, cyclopentane diyl group, cyclohexane diyl group; groups obtained by combining these, etc. When the saturated hydrocarbylene group contains an ether bond, when b1 in formula (A3-1) is 1, it may be located at any position except between the α-carbon atom and the β-carbon atom with respect to the ester oxygen atom. When b1 is 0, the atom bonding to the main chain becomes an etheric oxygen atom, and a second ether bond may be located at any position except between the α-carbon atom and the β-carbon atom with respect to the etheric oxygen atom. Note that when the number of carbon atoms of the saturated hydrocarbylene group is 10 or less, it is preferable because sufficient solubility in an alkaline developer can be obtained.

[0117] In formula (A3-1), X is an acid-labile group when b4 is 1, and is a hydrogen atom or an acid-labile group when b4 is 2 or more, provided that at least one is an acid-labile group. That is, the repeating unit A3-1 is one in which at least one phenolic hydroxy group bonded to an aromatic ring is protected by an acid-labile group, or one in which at least one carboxy group bonded to an aromatic ring is protected by an acid-labile group. As such an acid-labile group, any one can be used without particular limitation as long as it is one that has been used in many known chemically amplified positive resist compositions and dissociates by an acid to give an acidic group.

[0118] When a tertiary saturated hydrocarbyl group is selected as the acid-labile group, a resist film thickness is formed to be, for example, 10 to 100 nm, and even when a fine pattern having a line width of 45 nm or less is formed, it is preferable because it gives a pattern with small LER. As the tertiary saturated hydrocarbyl group, in order to obtain the resulting monomer for polymerization by distillation, it is preferably one having 4 to 18 carbon atoms. Further, examples of the group bonded to the tertiary carbon atom of the tertiary saturated hydrocarbyl group include saturated hydrocarbyl groups having 1 to 15 carbon atoms which may contain an oxygen-containing functional group such as an ether bond or a carbonyl group, and the groups bonded to the tertiary carbon atom may be bonded to each other to form a ring.

[0119] Specific examples of the group bonded to the tertiary carbon atom include a methyl group, an ethyl group, a propyl group, an adamantyl group, a norbornyl group, a tetrahydrofuran-2-yl group, a 7-oxanorborna-2-yl group, a cyclopentyl group, a 2-tetrahydrofuryl group, tricyclo[5.2.1.0 2,6 decyl group, tetracyclo[4.4.0.1 2,5 .1 7,10 dodecyl group, 3-oxo-1-cyclohexyl group.

[0120] In addition, examples of the tertiary saturated hydrocarbyl group having these as substituents include a tert-butyl group, a tert-pentyl group, a 1-ethyl-1-methylpropyl group, a 1,1-diethylpropyl group, a 1,1,2-trimethylpropyl group, a 1-adamantyl-1-methylethyl group, a 1-methyl-1-(2-norbornyl)ethyl group, a 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, a 1-methyl-1-(7-oxanorboran-2-yl)ethyl group, a 1-methylcyclopentyl group, a 1-ethylcyclopentyl group, a 1-propylcyclopentyl group, a 1-isopropylcyclopentyl group, a 1-cyclopentylcyclopentyl group, a 1-cyclohexylcyclopentyl group, a 1-(2-tetrahydrofuryl)cyclopentyl group, a 1-(7-oxanorboran-2-yl)cyclopentyl group, a 1-methylcyclohexyl group, a 1-ethylcyclohexyl group, a 1-cyclopentylcyclohexyl group, a 1-cyclohexylcyclohexyl group, a 2-methyl-2-norbornyl group, a 2-ethyl-2-norbornyl group, an 8-methyl-8-tricyclo[5.2.1.0 2,6 decyl group, an 8-ethyl-8-tricyclo[5.2.1.0 2,6 decyl group, a 3-methyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 dodecyl group, a 3-ethyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 dodecyl group, a 2-methyl-2-adamantyl group, a 2-ethyl-2-adamantyl group, a 1-methyl-3-oxo-1-cyclohexyl group, a 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, a 5-hydroxy-2-methyl-2-adamantyl group, a 5-hydroxy-2-ethyl-2-adamantyl group, but are not limited thereto.

[0121] In addition, examples of the acid-labile group include a group represented by the following formula (A3-1'). The group represented by the formula (A3-1') is often used as an acid-labile group and is a useful option as an acid-labile group that stably provides a pattern in which the interface between the pattern and the substrate is relatively rectangular. When X is a group represented by the formula (A3-1'), an acetal structure is formed. [Chemical formula]

[0122] In formula (A3-1’), R’ L1 is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R’ L2 is a saturated hydrocarbyl group having 1 to 30 carbon atoms. The saturated hydrocarbyl group may be linear, branched, or cyclic.

[0123] R’ L1 is appropriately selected according to the design of the sensitivity of the decomposable group to an acid. For example, if the design is to decompose with a strong acid while ensuring relatively high stability, a hydrogen atom is selected. If the design is to increase the sensitivity to pH changes using relatively high reactivity, a linear alkyl group is selected. Depending on the combination with the acid generator and basic compound formulated in the resist composition, when a relatively large alkyl group is selected at the end as R’ L2 and the solubility change due to decomposition is designed to be large, as R’ L1 it is preferable that the carbon atom bonded to the acetal carbon is a secondary carbon atom. Examples of R’ L1 bonded to the acetal carbon by a secondary carbon atom include an isopropyl group, a sec-butyl group, a cyclopentyl group, a cyclohexyl group, and the like.

[0124] Among the acetal groups, in order to obtain higher resolution, R’ L2 is preferably a polycyclic alkyl group having 7 to 30 carbon atoms. Also, when R’ L2 is a polycyclic alkyl group, it is preferable that a bond is formed between the secondary carbon atom constituting the polycyclic ring structure and the acetal oxygen. When bonded on the secondary carbon atom of the ring structure, compared to when bonded on the tertiary carbon atom, the polymer becomes a stable compound, the storage stability of the resist composition is good, and the resolution does not deteriorate. Also, R’ L2Even when compared with the case where it is bonded on a primary carbon atom with a linear alkyl group having 1 or more carbon atoms intervening, the glass transition temperature (Tg) of the polymer is good, and the resist pattern after development does not cause shape defects due to baking.

[0125] Preferred examples of the group represented by formula (A3-1’) include, but are not limited to, those shown below. In the following formulas, R’ L1 is the same as described above.

Chemical formula

[0126] Further, as the repeating unit having an acidic functional group protected by the acid-labile group, a repeating unit represented by the following formula (A3-2) (hereinafter, also referred to as repeating unit A3-2) may be included. The repeating unit represented by formula (A3-2) is a useful option as an acid-labile group-containing unit that gives good performance against line width fluctuations in development loading because the dissolution rate in the exposed area is high.

Chemical formula

[0127] In formula (A3-2), c1 is an integer of 0 to 2. c2 is an integer of 0 to 2. c3 is an integer of 0 to 5. c4 is an integer of 0 to 2.

[0128] In formula (A3-2), R A is, independently of each other, a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0129] In formula (A3-2), A 4 is a single bond, a phenylene group, a naphthylene group or *-C(=O)-O-A 41 -. A 41 is a hydroxyl group, an ether bond, an ester bond, or an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a lactone ring, or a phenylene group or a naphthylene group.

[0130] In formula (A3-2), R' 13 and R' 14 are, independently of each other, a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, and R' 13 and R' 14 may be bonded to each other to form a ring together with the carbon atom to which they are bonded.

[0131] In formula (A3-2), R' 15 is, independently of each other, a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms.

[0132] In formula (A3-2), R' 16 is, independently of each other, a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom.

[0133] Preferred examples of the repeating unit A3-2 include, but are not limited to, those shown below. In the following formula, R A is the same as described above. [Chemical formula]

[0134] As other acid-labile groups, those in which the hydrogen atom of the phenolic hydroxy group is substituted with -CH2COO-(tertiary saturated hydrocarbyl group) can also be used. At this time, as the tertiary saturated hydrocarbyl group, the same group as the tertiary saturated hydrocarbyl group used for protecting the phenolic hydroxy group described above can be used.

[0135] The repeating unit A2 is preferably introduced in the range of 4 to 40 mol% in all the repeating units of the polymer. The repeating units A3-1 and A3-2 are preferably introduced in the range of 2 to 40 mol% in all the repeating units of the polymer. The repeating units A2, A3-1 and A3-2 together are preferably introduced in the range of 8 to 60 mol% in all the repeating units of the polymer, more preferably 10 to 50 mol%, and still more preferably 10 to 40 mol%.

[0136] The polymer may further contain at least one selected from the repeating units C1 to C8 represented by any of the following formulas (C1) to (C8). [Chemical formula] (In the formula, R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Y 1 is 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-Y 11 -, *-C(=O)-O-Y 11 - or *-C(=O)-NH-Y 11 -, and Y 11is 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. Y 2 is a single bond or **-Y 21 -C(=O)-O-, and Y 21 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a hetero atom. Y 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-O-Y 31 -, *-C(=O)-O-Y 31 - or *-C(=O)-NH-Y 31 -. Y 31 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a group having 7 to 20 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * is a bond to a carbon atom of the main chain, and ** is a bond to an oxygen atom in the formula. Y 4 is a single bond or a hydrocarbylene group having 1 to 30 carbon atoms which may contain a hetero atom. k 1 and k 2 are each independently 0 or 1, provided that when Y 4 is a single bond, k 1 and k 2 are 0. R 51 ~R 68 are each independently a halogen atom, or a hydrocarbyl group having 1 to 25 carbon atoms which may contain a hetero atom. Also, R 51 and R 52 may combine with each other to form a ring together with the sulfur atom to which they are attached, and R 53 and R 54 、R 56 and R 57 、and R 59 and R 60 may each combine with each other to form a ring together with the sulfur atom to which they are attached. R HFis a hydrogen atom or a trifluoromethyl group. Xa - is a non-nucleophilic counter ion.)

[0137] In formulas (C1) to (C8), R A is the same as described above. Y 1 is 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-Y 11 -, *-C(=O)-O-Y 11 - or *-C(=O)-NH-Y 11 -, and Y 11 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. Y 2 is a single bond or **-Y 21 -C(=O)-O-, and Y 21 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a hetero atom. Y 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-O-Y 31 -, *-C(=O)-O-Y 31 - or *-C(=O)-NH-Y 31 -. Y 31 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a group having 7 to 20 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * is a bond to a carbon atom of the main chain, and ** is a bond to an oxygen atom in the formula. Y 4 is a single bond or a hydrocarbylene group having 1 to 30 carbon atoms which may contain a hetero atom. k 1 and k 2 are each independently 0 or 1, provided that when Y 4 is a single bond, k 1 and k 2is 0.

[0138] When the repeating unit represented by formula (C4) or (C8) is irradiated with high-energy rays such as ultraviolet rays, far ultraviolet rays, EB, EUV, X-rays, γ-rays, synchrotron radiation, etc., it generates an acid in which the β-position of the sulfonyl group is difluoromethylated. The acid has an acid strength suitable for deprotecting the polymer containing the repeating unit A2. Further, when a polymer containing the repeating unit represented by formula (C4) or (C8) is used as the polymer of a chemically amplified positive resist composition, it is possible to appropriately control the movement and diffusion of the generated acid.

[0139] Photoacid generators that generate arenesulfonic acid upon irradiation with high-energy rays are also commonly used for deprotecting polymers containing units protected with an acetal group, a tertiary alkyl group, or a tert-butoxycarbonyl group. However, in order to obtain the effects of the present invention, even when an arenesulfonic acid generating unit is introduced as a repeating unit of the base polymer, the base polymer may not dissolve in the solvent due to its low solvent solubility. On the other hand, the polymer containing the repeating unit represented by formula (C4) or (C8) of the present invention has sufficient fat solubility, so its production and handling are easy, and the preparation of the resist composition is also easy.

[0140] In formulas (C2) and (C6), Y 2 is -Y 21 -C(=O)-O-, examples of the hydrocarbylene group which may contain a hetero atom represented by Y 21 include, but are not limited to, the following.

Chemical formula

[0141] In formulas (C2) and (C6), R HF is a hydrogen atom or a trifluoromethyl group. In the repeating units C2 and C6, R HFSpecific examples where it is a hydrogen atom include those described in JP-A-2010-116550, and R HF Specific examples where it is a trifluoromethyl group include those described in JP-A-2010-077404. Examples of repeating units C3 and C7 include those described in JP-A-2012-246265 and JP-A-2012-246426.

[0142] In formulas (C1) and (C5), Xa - is a non-nucleophilic counter ion. Examples of non-nucleophilic counter ions represented by Xa - include those described in JP-A-2010-113209 and JP-A-2007-145797.

[0143] Y 4The hydrocarbylene group having 1 to 30 carbon atoms which may contain a heteroatom represented by may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkanediyl groups such as methanediyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group; cyclic saturated hydrocarbylene groups such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group; arylene groups such as phenylene group, methylphenylene group, ethylphenylene group, n-propylphenylene group, isopropylphenylene group, n-butylphenylene group, isobutylphenylene group, sec-butylphenylene group, tert-butylphenylene group, naphthylene group, methylnaphthylene group, ethylnaphthylene group, n-propylnaphthylene group, isopropylnaphthylene group, n-butylnaphthylene group, isobutylnaphthylene group, sec-butylnaphthylene group, tert-butylnaphthylene group; groups obtained by combining these, and the like.

[0144] Further, some or all of the hydrogen atoms of the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, etc., and a part of -CH2- constituting the hydrocarbylene group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc., and as a result, a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. may be formed.

[0145] Preferred examples of anions of monomers that give repeating units C4 and C8 include, but are not limited to, those shown below. [Chemical formula]

[0146] [Chemical formula]

[0147] In formulas (C1) to (C8), R 51 ~R 68 are each independently a halogen atom or a hydrocarbyl group having 1 to 25 carbon atoms which may contain a heteroatom.

[0148] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.

[0149] The hydrocarbyl group having 1 to 25 carbon atoms may be saturated or unsaturated and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 25 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, etc.; cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6Cyclic saturated hydrocarbyl groups having 3 to 25 carbon atoms such as a decanyl group, an adamantyl group, an adamantylmethyl group; aryl groups having 6 to 25 carbon atoms such as a phenyl group, a naphthyl group, an anthracenyl group, etc. may be mentioned. Further, 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, a halogen atom, etc., and a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. may be interposed between the carbon-carbon bonds of the hydrocarbyl group. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0150] Also, R 53 and R 54 , R 56 and R 57 , and R 59 and R 60 may each be bonded to each other to form a ring together with the sulfur atom to which they are bonded. Examples of the ring formed at this time include those shown below.

Chemical formula

[0151] In formulas (C2) to (C4), specific structures of the sulfonium cation include, but are not limited to, those shown below.

Chemical formula

[0152]

Chemical formula

[0153]

Chemical formula

[0154]

Chem.

[0155]

Chem.

[0156]

Chem.

[0157]

Chem.

[0158]

Chem.

[0159]

Chem.

[0160]

Chem.

[0161]

Chem.

[0162]

Chem.

[0163]

Chem.

[0164]

Chem.

[0165]

Chem.

[0166]

Chem.

[0167]

Chem.

[0168]

Chem.

[0169]

Chem.

[0170]

Chem.

[0171]

Chem.

[0172]

Chem.

[0173] In formulas (C6) to (C8), specific structures of the iodonium cation include, but are not limited to, those shown below.

Chem.

[0174] [Chemical formula]

[0175] Among the repeating units C1 to C8, the unit preferable for the processing of the photomask blank is the repeating unit C4 because it has an optimal acid strength in designing the acid-labile group of the polymer.

[0176] The repeating units C1 to C8 are units that generate acid upon irradiation with high-energy rays. By including these units in the polymer, it is considered that acid diffusion can be moderately suppressed and a pattern with reduced LER can be obtained. In addition, by including these units in the polymer, the phenomenon in which acid volatilizes from the exposed portion and reattaches to the unexposed portion during baking in a vacuum is suppressed, and it is considered effective for reducing LER and reducing shape deterioration due to unwanted film loss in the unexposed portion.

[0177] The repeating units C1 to C8 are preferably introduced in the range of 0.1 to 30 mol% and more preferably in the range of 0.5 to 20 mol% in all the repeating units of the polymer. The repeating units C1 to C8 may be used alone or in combination of two or more.

[0178] In all the repeating units of the polymer, the content of the repeating unit having an aromatic ring skeleton is preferably 65 mol% or more, more preferably 75 mol% or more, and still more preferably 85 mol% or more. When not including the repeating units C1 to C8, it is preferable that all the units have an aromatic ring skeleton.

[0179] In all the repeating units of the polymer, the content of at least one selected from the repeating unit A1, the repeating unit A2, the repeating unit A3-1, the repeating unit A3-2, and the repeating units B1 to B3 is preferably 70 mol% or more, more preferably 80 mol% or more, and still more preferably 90 mol% or more.

[0180] The polymer may contain commonly used (meth)acrylate ester units protected with acid-labile groups, and (meth)acrylate ester units having an adhesion group such as a lactone structure or a hydroxy group other than a phenolic hydroxy group. The characteristics of the resist film can be finely adjusted by these repeating units, but these units may not be included.

[0181] Examples of the (meth)acrylate ester unit having the adhesion group include a repeating unit represented by the following formula (B4) (hereinafter also referred to as repeating unit B4), a repeating unit represented by the following formula (B5) (hereinafter also referred to as repeating unit B5), and a repeating unit represented by the following formula (B6) (hereinafter also referred to as repeating unit B6). These units do not show acidity and can be used as auxiliary units for imparting adhesion to the substrate or adjusting solubility.

Chemical formula

[0182] In formulas (B4) to (B6), R A is the same as described above. R 71 is -O- or a methylene group. R 72 is a hydrogen atom or a hydroxy group. R 73 is a saturated hydrocarbyl group having 1 to 4 carbon atoms. h is an integer from 0 to 2.

[0183] When repeating units B4 to B6 are included, their content is preferably 0 to 20 mol%, more preferably 0 to 10 mol% in all the repeating units of the polymer. The repeating units B4 to B6 may be used alone or in combination of two or more.

[0184] The polymer can be synthesized by copolymerizing each monomer protected with a protecting group, if necessary, by a known method and then performing a deprotection reaction, if necessary. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, reference can be made to JP-A-2004-115630.

[0185] The polymer preferably has a weight average molecular weight (Mw) of 1,000 to 50,000, more preferably 2,000 to 20,000. If Mw is 1,000 or more, there is no possibility of a phenomenon such as the head of the pattern becoming round and the resolution decreasing, and the LER deteriorating, as is conventionally known. On the other hand, if Mw is 50,000 or less, there is no possibility of the LER deteriorating, particularly when forming a pattern with a pattern line width of 100 nm or less. In the present invention, Mw is a polystyrene-equivalent measurement value by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0186] The polymer preferably has a narrow molecular weight distribution (Mw / Mn) of 1.0 to 2.0, preferably 1.0 to 1.9, more preferably 1.0 to 1.8. When the distribution is narrow in this way, foreign matter does not occur on the pattern and the shape of the pattern does not deteriorate after development.

[0187] In addition, the dissolution rate of the polymer in an alkaline developer is preferably 10 nm / min or less, more preferably 7 nm / min or less, and still more preferably 5 nm / min or less. In the latest generation, when the coating film on the substrate is in the thin film region (100 nm or less), since the influence of pattern film loss on alkali development is large, if the alkali dissolution rate of the polymer is 10 nm / min or less, the pattern will not collapse and a fine pattern can be formed. In particular, in the production of photomasks where no defects are required, this is remarkable because the development process has a strong tendency. In the present invention, the dissolution rate of the polymer in an alkaline developer is a value calculated from the film loss amount when a polymer solution (polymer concentration: 16.7% by mass, solvent: propylene glycol monomethyl ether acetate (PGMEA)) is spin-coated on a 200 mm (8-inch) silicon wafer, baked at 100°C for 90 seconds to form a film with a thickness of 1,000 nm, and then developed with a 2.38% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) at 23°C for 100 seconds.

[0188] [Chemically amplified positive resist composition] The chemically amplified positive resist composition of the present invention contains the polymer described above. In addition, it can contain an organic solvent, a photoacid generator, a quencher, a fluorine atom-containing polymer, and the like. Hereinafter, the chemically amplified positive resist composition of the present invention will be described in detail.

[0189] As the design of the above chemically amplified positive resist composition, in addition to the polymer having the formula (A2) shown in the present invention, it can also be mixed with a polymer having an acid-labile group protected by a known tertiary alkyl group or a tert-butoxycarbonyl group. However, in order to exhibit the effects of the present invention, the proportion of the polymer having the formula (A2) shown in the present invention in all the polymers contained in the chemically amplified positive resist composition is preferably 30% or more.

[0190] [Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention shields high contrast, chemical flare of acid in high energy ray irradiation, and mixing of acid from the antistatic film material in the process of applying the antistatic film material onto the resist film, and suppresses unexpected unnecessary pattern deterioration. For this purpose, it may contain a fluorine atom-containing polymer including at least one selected from the repeating unit represented by the following formula (D1), the repeating unit represented by the following formula (D2), the repeating unit represented by the following formula (D3), and the repeating unit represented by the following formula (D4) (hereinafter, also referred to as repeating units D1, D2, D3, and D4, respectively). Since the fluorine atom-containing polymer also has the function of a surfactant, it can prevent reattachment of insoluble substances that may occur during the development process to the substrate, and thus also exhibits an effect on development defects. [Chemical formula] (In the formula, R B is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 101 , R 102 , R 104 and R 105 are independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 are independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid-labile group. When R 103 , R 106 , R 107 and R 108 are a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. m' is an integer of 1 to 3. Z 1 is a hydrocarbon group having (m'+1) valences and 1 to 20 carbon atoms or a fluorinated hydrocarbon group having (m'+1) valences and 1 to 20 carbon atoms.)

[0191] In formulas (D1) to (D4), R Bis independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 101 and R 102 and R 104 and R 105 are independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 and R 106 and R 107 and R 108 are independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms or an acid-labile group, and when R 103 and R 106 and R 107 and R 108 are a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. m' is an integer of 1 to 3. Z 1 is a hydrocarbon group having (m'+1) valences and having 1 to 20 carbon atoms or a fluorinated hydrocarbon group having (m'+1) valences and having 1 to 20 carbon atoms.

[0192] In formulas (D1) and (D2), examples of the saturated hydrocarbyl group having 1 to 10 carbon atoms represented by R 101 and R 102 and R 104 and R 105 include alkyl groups having 1 to 10 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, adamantyl group, norbornyl group. Among these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0193] In formulas (D1) to (D4), R 103 and R 106 and R 107 and R 108Examples of the hydrocarbyl group having 1 to 15 carbon atoms represented by include an alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, an alkynyl group having 2 to 15 carbon atoms, etc., and an alkyl group having 1 to 15 carbon atoms is preferred. Examples of the alkyl group include, in addition to those described above, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, etc. Further, examples of the fluorinated hydrocarbyl group include a group in which some or all of the hydrogen atoms bonded to the carbon atoms of the above-described hydrocarbyl group are substituted with fluorine atoms.

[0194] In formula (D4), Z 1 Examples of the (m'+1)-valent hydrocarbon group having 1 to 20 carbon atoms represented by include a group obtained by further removing m' hydrogen atoms from an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms. Further, Z 1 Examples of the (m'+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by include a group in which at least one hydrogen atom of the above-described (m'+1)-valent hydrocarbon group is substituted with a fluorine atom.

[0195] Specific examples of the repeating units D1 to D4 include, but are not limited to, those shown below. In the following formulas, R B is the same as described above.

Chemical formula

[0196]

Chemical formula

[0197]

Chemical formula

[0198] Further, it is preferable that the fluorine atom-containing polymer further contains at least one selected from the repeating unit represented by the following formula (D5) and the repeating unit represented by the following formula (D6) (hereinafter, also referred to as repeating unit D5 and repeating unit D6, respectively).

Chemical formula

[0199] In formula (D5) and (D6), R C is each independently a hydrogen atom or a methyl group. R 109 is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a group containing a heteroatom intervening between carbon-carbon bonds.110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a group containing a heteroatom intervening between carbon-carbon bonds. R 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a part of -CH2- constituting the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. x is an integer of 1 to 3. y is an integer satisfying 0 ≦ y ≦ 5 + 2z - x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 - is. Z 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. Z 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * is a bond to a carbon atom of the main chain.

[0200] In formula (D5), R 109 and R 110 Examples of the hydrocarbyl group having 1 to 5 carbon atoms represented by include an alkyl group, an alkenyl group, an alkynyl group, etc., and an alkyl group is preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, an n-pentyl group, etc. Further, a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. may intervene between the carbon-carbon bonds of these groups.

[0201] In formula (D5), -OR 110 is preferably a hydrophilic group. In this case, R 110 is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms in which an oxygen atom intervenes between carbon-carbon bonds, etc.

[0202] In formula (D5), Z 2is preferably *-C(=O)-O- or *-C(=O)-NH-. Further, R C is preferably a methyl group. Z 2 The presence of a carbonyl group in improves the ability to trap the acid derived from the antistatic film. Further, when R C is a methyl group, a more rigid polymer with a higher glass transition temperature (Tg) is obtained, so that the diffusion of the acid is suppressed. As a result, the resist film has good stability over time, and the resolution and pattern shape do not deteriorate either.

[0203] Examples of the repeating unit D5 include, but are not limited to, those shown below. In the following formula, R C is the same as described above.

Chemical formula

[0204]

Chemical formula

[0205] In formula (D6), the saturated hydrocarbylene group having 1 to 10 carbon atoms represented by Z 3 may be linear, branched or cyclic. Specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,3-diyl group, a butane-1,4-diyl group, a 1,1-dimethylethane-1,2-diyl group and the like.

[0206] In formula (D6), R 111A saturated hydrocarbyl group having 1 to 20 carbon atoms, in which at least one hydrogen atom represented by is substituted with a fluorine atom, may be linear, branched or cyclic. Specific examples thereof include those in which at least one hydrogen atom of an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms is substituted with a fluorine atom.

[0207] Examples of the repeating unit D6 include, but are not limited to, those shown below. In the following formula, R C is the same as described above.

Chemical formula

[0208]

Chemical formula

[0209]

Chemical formula

[0210]

Chemical formula

[0211] The content of the repeating units D1 to D4 is preferably 15 to 95 mol%, more preferably 20 to 85 mol% in all the repeating units of the fluorine atom-containing polymer. The content of the repeating unit D5 and / or D6 is preferably 5 to 85 mol%, more preferably 15 to 80 mol% in all the repeating units of the fluorine atom-containing polymer. The repeating units D1 to D6 may be used alone or in combination of two or more.

[0212] The fluorine atom-containing polymer may contain other repeating units in addition to the repeating units described above. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of JP-A-2014-177407. When the fluorine atom-containing polymer contains other repeating units, the content thereof is preferably 50 mol% or less based on all the repeating units of the fluorine atom-containing polymer.

[0213] The fluorine atom-containing polymer can be synthesized by copolymerizing each monomer protected with a protecting group, if necessary, by a known method, and then performing a deprotection reaction, if necessary. The copolymerization reaction is not particularly limited, but radical polymerization and anionic polymerization are preferred. For these methods, reference can be made to JP-A-2004-115630.

[0214] The Mw of the fluorine atom-containing polymer is preferably from 2,000 to 50,000, more preferably from 3,000 to 20,000. If Mw is 2,000 or more, the acid does not diffuse, the resolution does not deteriorate, and the stability over time is not impaired. If Mw is 50,000 or less, the solubility in the solvent is sufficient and coating defects do not occur. Further, the fluorine atom-containing polymer preferably has an Mw / Mn of from 1.0 to 2.2, more preferably from 1.0 to 1.7.

[0215] When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer, the content thereof is preferably from 0.01 to 30 parts by mass, more preferably from 0.1 to 20 parts by mass, still more preferably from 0.5 to 10 parts by mass, based on 80 parts by mass of the polymer.

[0216] [Photoacid generator] The chemically amplified positive resist composition of the present invention may contain a photoacid generator. The photoacid generator is not particularly limited as long as it is a compound that generates an acid upon irradiation with high-energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethanes, N-sulfonyloxyimides, oxime-O-sulfonate type acid generators, and the like.

[0217] Specific examples of the photoacid generator include nonafluorobutanesulfonate, partially fluorinated sulfonates described in paragraphs

[0247] to

[0251] of JP-A-2012-189977, partially fluorinated sulfonates described in paragraphs

[0261] to

[0265] of JP-A-2013-101271, those described in paragraphs

[0122] to

[0142] of JP-A-2008-111103, and those described in paragraphs

[0080] to

[0081] of JP-A-2010-215608. Among these specific examples, arylsulfonate-type or alkanesulfonate-type photoacid generators are preferred because they generate an acid with an appropriate strength to deprotect the acid-labile group of the repeating unit represented by formula (A1).

[0218] As such a photoacid generator, a compound having an anion with the structure shown below is preferred.

Chemical formula

[0219]

Chemical formula

[0220]

Chemical formula

[0221]

Chemical formula

[0222]

Chemical formula

[0223]

Chemical formula

[0224] [Chemistry]

[0225] [Chemistry]

[0226] Preferably, the photoacid generator contains an anion structure of a photoacid generator represented by the following formula (M-1). [Chemistry] (In formula (M-1), m is 0 or 1. p is an integer from 1 to 3. q is an integer from 1 to 5. r is an integer from 0 to 3. L 1 is a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. L 2 is an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. X 4 When p is 1, is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms, and when p is 2 or 3, is a (p + 1)-valent hydrocarbon group having 1 to 20 carbon atoms. The hydrocarbylene group and the (p + 1)-valent hydrocarbon group may contain at least one 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. Rf 1 and Rf 2 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. R 21 is a hydroxy group, a carboxy group, 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, a fluorine atom, a chlorine atom, a bromine atom, an amino group, -N(R 1A )-C(=O)-R 1B or -N(R 1A )-C(=O)-O-R 1B and R1A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 1B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 22 is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, and part or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and part or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, and a hydroxy group. )

[0227] In formula (M-1), m is 0 or 1. p is an integer from 1 to 3. q is an integer from 1 to 5. r is an integer from 0 to 3.

[0228] In formula (M-1), L 1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond.

[0229] In formula (M-1), L 2 is an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, or a carbamate bond.

[0230] In formula (M-1), X 4 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms when p is 1, and is a (p + 1)-valent hydrocarbon group having 1 to 20 carbon atoms when p is 2 or 3, and the hydrocarbylene group and the (p + 1)-valent hydrocarbon group may contain at least one 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.

[0231] X 4The hydrocarbylene group having 1 to 20 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkanediyl groups having 1 to 20 carbon atoms such as methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, adamantanediyl group; unsaturated aliphatic hydrocarbylene groups having 2 to 20 carbon atoms such as vinylene group, propene-1,3-diyl group; arylene groups having 6 to 20 carbon atoms such as phenylene group, naphthylene group; groups obtained by combining these, etc. Further, X 4 The (p + 1)-valent hydrocarbon group having 1 to 20 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include groups obtained by removing one or two hydrogen atoms from the specific examples of the hydrocarbylene group having 1 to 20 carbon atoms described above.

[0232] In formula (M-1), Rf 1 and Rf 2 are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group.

[0233] In formula (M-1), R 21 is a hydroxy group, a carboxy group, 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, a fluorine atom, a chlorine atom, a bromine atom, an amino group, -N(R 1A )-C(=O)-R 1B or -N(R 1A )-C(=O)-O-R 1B wherein R 1Ais a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 1B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0234] R 21 、R 1A and R 1B The saturated hydrocarbyl groups having 1 to 6 carbon atoms represented by may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 6 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group; and cyclic saturated hydrocarbyl groups having 3 to 6 carbon atoms such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group. Further, as the saturated hydrocarbyl moiety of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms represented by R 21 are the same as the specific examples of the saturated hydrocarbyl groups described above, and the saturated hydrocarbyl moiety of the saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms represented by R 21 represented by carbon Among the specific examples of the saturated hydrocarbyl groups having 1 to 6 carbon atoms described above, those having 1 to 5 carbon atoms are included.

[0235] R 1B The unsaturated aliphatic hydrocarbyl groups having 2 to 8 carbon atoms represented by may be linear, branched or cyclic. Specific examples thereof include alkenyl groups having 2 to 8 carbon atoms such as vinyl group, propenyl group, butenyl group, hexenyl group; alkynyl groups having 2 to 8 carbon atoms such as ethynyl group, propynyl group, butynyl group; and cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 8 carbon atoms such as cyclohexenyl group, norbornenyl group.

[0236] In formula (M-1), R 22is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, and a part or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and a part or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from saturated hydrocarbyl groups having 1 to 20 carbon atoms, saturated hydrocarbyloxy groups having 1 to 20 carbon atoms, aryl groups having 6 to 14 carbon atoms, halogen atoms, and hydroxy groups.

[0237] R 22 The hydrocarbylene group having 1 to 20 carbon atoms represented by may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include X 4 The same as those exemplified as the hydrocarbylene group having 1 to 20 carbon atoms represented by.

[0238] R 22 Specific examples of the arylene group having 6 to 14 carbon atoms represented by include a phenylene group, a naphthylene group, a phenanthrenediyl group, an anthracenediyl group, and the like. The hydrocarbyl moieties of the saturated hydrocarbyl group having 1 to 20 carbon atoms and the saturated hydrocarbyloxy group having 1 to 20 carbon atoms, which are substituents of the arylene group, may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group; and cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, adamantyl group. Specific examples of the arylene group having 6 to 14 carbon atoms, which is a substituent of the arylene group, include a phenylene group, a naphthylene group, a phenanthrenediyl group, an anthracenediyl group, and the like.

[0239] It is more preferable that the photoacid generator includes an anion structure of a photoacid generator represented by the following formula (M-2).

Chemical formula

[0240] In formula (M-2), p, q, r, L 1 , X 4 , R 21 are the same as those described above. n is an integer from 1 to 4. R 2A is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, or a hydroxy group. When n is 2 to 4, each R 2A may be the same as or different from each other.

[0241] Examples of the anion of the sulfonic acid represented by formula (M-1) include, but are not limited to, those shown below.

[0242]

Chemical formula

[0243]

Chemical formula

[0244]

Chemical formula

[0245]

Chemical formula

[0246]

Chemical formula

[0247] [Chemistry]

[0248] [Chemistry]

[0249] [Chemistry]

[0250] [Chemistry]

[0251] [Chemistry]

[0252] [Chemistry]

[0253] [Chemistry]

[0254] [Chemistry]

[0255] [Chemistry]

[0256] [Chemistry]

[0257] [Chemistry]

[0258]

Chem.

[0259]

Chem.

[0260]

Chem.

[0261]

Chem.

[0262]

Chem.

[0263]

Chem.

[0264]

Chem.

[0265]

Chem.

[0266]

Chem.

[0267]

Chem.

[0268]

Chem.

[0269]

Chem.

[0270] As the cation that forms a pair with the anion, a sulfonium cation represented by the following formula (E) or an iodonium cation represented by the following formula (F) is preferable.

Chem.

[0271] In formulas (E) and (F), R 201 ~R 205 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom.

[0272] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.

[0273] The hydrocarbyl group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, tert-pentyl group, n-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, etc.; cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6Cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms such as decanyl group, adamantyl group, adamantylmethyl group; aryl groups having 6 to 20 carbon atoms such as phenyl group, naphthyl group, anthracenyl group, etc. are exemplified. Further, 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, a halogen atom, etc., and a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, etc. may be interposed between the carbon-carbon bonds of the hydrocarbyl group. As a result, it may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc.

[0274] Also, R 201 and R 202 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. Examples of the ring formed at this time include those shown below. [Chemical formula] (In the formula, the dashed line is a bond.)

[0275] Specific structures of the sulfonium cation include those similar to the sulfonium cation in formulas (C2) to (C4), but are not limited thereto.

[0276] Specific structures of the iodonium cation include those similar to the iodonium cation in formulas (C6) to (C8), but are not limited thereto.

[0277] The acid generated by the photoacid generator, i.e., the conjugate acid of the anion, preferably has an acid strength (pKa) of -2.0 or more, more preferably -1.0 or more. The upper limit of pKa is preferably 2.0. The pKa value is calculated using the pKa DB in the software ACD / Chemsketch ver:9.04 manufactured by Advanced Chemistry Development, Inc. With such a chemically amplified positive resist composition containing a photoacid generator, the deprotection reaction of the acid-labile group of the polymer is catalyzed and the developability becomes good.

[0278] When the chemically amplified positive resist composition of the present invention contains a photoacid generator, its content is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass with respect to 80 parts by mass of the polymer. The photoacid generator may be used alone or in combination of two or more.

[0279] [Quencher] The chemically amplified positive resist composition of the present invention preferably contains a quencher (acid diffusion inhibitor). Examples of the quencher include conventional basic compounds. Examples of the conventional basic compounds include primary, secondary, and tertiary aliphatic amines, hybrid 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, carbamates, and the like. In particular, primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, a sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent No. 3790649 are preferable. Preferred examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, imidazole derivatives, and the like. By adding such a basic compound, for example, the acid diffusion rate in the resist film can be further suppressed, and the shape can be corrected.

[0280] In addition, examples of the quencher include onium salts such as sulfonium salts, iodonium salts, and ammonium salts of carboxylic acids whose α-position is not fluorinated, as described in JP-A-2008-158339. Sulfonic acids, imidic acids, or methidic acids whose α-position is fluorinated are necessary for deprotecting acid-labile groups, but carboxylic acids whose α-position is not fluorinated are released by salt exchange with onium salts whose α-position is not fluorinated. Carboxylic acids whose α-position is not fluorinated hardly cause a deprotection reaction and thus function as a quencher.

[0281] Examples of the onium salts of carboxylic acids whose α-position is not fluorinated include those represented by the following formula (C’1). [Chemical formula]

[0282] In formula (C’1), R 69 is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hydrogen atom or a hetero atom, provided that the hydrogen atom bonded to the carbon atom at the α-position of the carboxy group is excluded from those substituted with a fluorine atom or a fluoroalkyl group.

[0283] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, tert-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, etc.; cyclic saturated hydrocarbyl groups having 3 to 40 carbon atoms such as cyclopentyl group, cyclohexyl group, cyclopentylmethyl group, cyclopentylethyl group, cyclopentylbutyl group, cyclohexylmethyl group, cyclohexylethyl group, cyclohexylbutyl group, norbornyl group, tricyclo[5.2.1.0 2,6 decanyl group, adamantyl group, adamantylmethyl group, etc.; alkenyl groups having 2 to 40 carbon atoms such as vinyl group, allyl group, propenyl group, butenyl group, hexenyl group, etc.; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 40 carbon atoms such as cyclohexenyl group, etc.; aryl groups having 6 to 40 carbon atoms such as phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 4-n-butylphenyl group, etc.), dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl group (methylnaphthyl group, ethylnaphthyl group, etc.), dialkylnaphthyl group (dimethylnaphthyl group, diethylnaphthyl group, etc.), etc.; aralkyl groups having 7 to 40 carbon atoms such as benzyl group, 1-phenylethyl group, 2-phenylethyl group, etc.

[0284] Further, 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 -CH2- of the hydrocarbyl group may be substituted with a heteroatom-containing group such as an oxygen atom, a sulfur atom, or a nitrogen atom. As a result, it may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic acid anhydride (-C(=O)-O-C(=O)-), a haloalkyl group, etc. 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 such as a 2-phenyl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0285] In formula (C'1), Mq + is an onium cation. As the onium cation, a sulfonium cation, an iodonium cation, or an ammonium cation is preferable, and a sulfonium cation or an iodonium cation is more preferable. Specific examples of the sulfonium cation include the same ones as those exemplified as the cation of the sulfonium salts represented by formulas (C2) to (C4). Specific examples of the iodonium cation include the same ones as those exemplified as the cation of the iodonium salts represented by formulas (C6) to (C8).

[0286] Examples of the anion of the onium salt represented by formula (C'1) include, but are not limited to, those shown below. [Chemistry]

[0287] [Chemistry]

[0288] [Chemistry]

[0289] As the quencher, a sulfonium salt of a carboxylic acid containing an iodinated benzene ring represented by the following formula (C'2) can also be preferably used. [Chemistry]

[0290] In formula (C'2), s is an integer from 1 to 5. t is an integer from 0 to 3. u is an integer from 1 to 3. s + t is an integer from 1 to 5.

[0291] In formula (C'2), R 71 is 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 part or all of the hydrogen atoms may be substituted by halogen atoms, or -N(R 71A )-C(=O)-R 71B or -N(R 71A )-C(=O)-O-R 71B . R 71A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. R 71B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When t and / or u is 2 or more, each R 71 may be the same as or different from each other.

[0292] In formula (C’2), L 11 is a single bond or a (u + 1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one 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.

[0293] In formula (C’2), R 72 , R 73 and R 74 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, etc. Further, part or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone ring, a sulfo group, or a sulfonium salt-containing group, and part of -CH2- of the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonic acid ester bond. Further, R 72 and R 73 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded.

[0294] Specific examples of the compound represented by formula (C’2) include those described in JP-A-2017-219836. The compound represented by formula (C’2) has high absorption, a high sensitizing effect, and a high acid diffusion control effect.

[0295] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (C’3) can also be used.

Chemical formula

[0296] In formula (C'3), R 81 ~R 84 are each independently a hydrogen atom, -L 12 -CO2 - , or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. R 81 and R 82 and, R 82 and R 83 and, and R 83 and R 84 and may each be bonded to each other to form a ring together with the carbon atom to which they are bonded. L 12 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. R 85 is a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom.

[0297] In formula (C'3), ring R is a ring having 2 to 6 carbon atoms containing the carbon atoms and nitrogen atoms in the formula, and part or all of the hydrogen atoms bonded to the carbon atoms of the ring are a hydrocarbyl group having 1 to 20 carbon atoms, or -L 12 -CO2 - and may be substituted, and part of the carbon atoms of the ring may be substituted with a sulfur atom, an oxygen atom or a nitrogen atom. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5-membered ring or a 6-membered ring. Specific examples thereof include a pyridine ring, a pyrrole ring, a pyrrolidine ring, a piperidine ring, a pyrazole ring, an imidazoline ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring O oxazole ring, thiazole ring, morpholine ring, thiazine ring, triazole ring and the like.

[0298] The onium carboxylate salt represented by formula (C'3) has at least one -L 12 -CO2 - group. That is, at least one of R 81 ~R 84 is -L 12 -CO2 -and / or at least one of the hydrogen atoms bonded to the carbon atoms of ring R is -L 12 -CO2 - and is substituted therewith.

[0299] In formula (C'3), Q + is a sulfonium cation, an iodonium cation or an ammonium cation, with the sulfonium cation being preferred. Specific examples of the sulfonium cation include the same ones as those exemplified as the sulfonium cation in formulas (C2) to (C4).

[0300] Examples of the anion of the compound represented by formula (C'3) include, but are not limited to, those shown below.

Chemical formula

[0301]

Chemical formula

[0302]

Chemical formula

[0303]

Chemical formula

[0304]

Chemical formula

[0305]

Chemical formula

[0306] Also, as the quencher, a betaine-type compound of a weak acid can also be used. Specific examples thereof include, but are not limited to, those shown below. [Chemical formula]

[0307] As the quencher, a polymer-type quencher described in JP-A-2008-239918 can be further mentioned. This enhances the rectangularity of the resist pattern by orienting on the surface of the resist film. The polymer-type quencher also has an effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for immersion exposure is applied.

[0308] When the chemically amplified positive resist composition of the present invention contains a quencher, its content is preferably 0 to 50 parts by mass, more preferably 0.1 to 40 parts by mass, based on 80 parts by mass of the polymer. The quencher may be used alone or in combination of two or more.

[0309] When the chemically amplified positive resist composition of the present invention contains both a photoacid generator and a quencher, the content ratio of the photoacid generator to the quencher (photoacid generator / quencher) is preferably included so as to be less than 3 in terms of mass ratio, more preferably less than 2.5, and still more preferably less than 2. When the content ratio of the photoacid generator to the quencher contained in the chemically amplified positive resist composition is within the above range, acid diffusion can be sufficiently suppressed, and excellent resolution and dimensional uniformity can be obtained.

[0310] [Organic solvent] The chemically amplified positive resist composition of the present invention may contain an organic solvent. The organic solvent is not particularly limited as long as it can dissolve each component. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-pentyl ketone described in paragraphs

[0144] to

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; ethers such as propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monoethyl ether acetate (PGMEA), ethyl lactate (EL), ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as γ-butyrolactone; and mixed solvents thereof. When an acetal-based acid-labile group is used, a high-boiling alcohol-based solvent, specifically, diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, 1,3-butanediol, etc. can be added to accelerate the deprotection reaction of the acetal.

[0311] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixed solvents thereof are preferred.

[0312] When the chemically amplified positive resist composition of the present invention contains the organic solvent, the content is preferably 200 to 10,000 parts by mass, more preferably 400 to 5,000 parts by mass, based on 80 parts by mass of the polymer. The organic solvent may be used alone or in combination of two or more.

[0313] [Surfactant] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant in order to improve the coatability on a substrate. When using a surfactant, as described in many examples in JP-A-2004-115630, many surfactants are known and can be selected with reference to them. The content of the surfactant is preferably 0 to 5 parts by mass with respect to 80 parts by mass of the polymer. When the fluorine atom-containing polymer is included in the chemically amplified positive resist composition of the present invention, since the fluorine atom-containing polymer also serves as a surfactant, the surfactant may not be included.

[0314] It is preferable to filter the chemically amplified positive resist composition of the present invention. As the filter type, by using nylon or polyethylene (PE), gel components and particles contained in the resist can be effectively removed. Further, in order to maintain the quality in the advanced generation, it is preferable to use a filter having a pore size of 20 nm or less.

[0315] Also, the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition of the present invention in an alkaline developer is preferably 10 nm / min or less, more preferably 9 nm / min or less, and still more preferably 8 nm / min or less. When the resist film is in the thin film region (100 nm or less), since the influence of pattern film loss in an alkaline developer is large, if the dissolution rate of the unexposed portion is 10 nm / min or less, the pattern does not collapse and a fine pattern can be formed. In particular, in the production of a photomask that requires no defects, this is remarkable because the developing process has a strong tendency. The dissolution rate of the unexposed portion is a value calculated from the film loss amount when a silicon wafer of 150 mm (6 inches) is spin-coated with the chemically amplified positive resist composition of the present invention, baked at 110° C. for 240 seconds to form a resist film with a film thickness of 80 nm, and then developed with a 2.38 mass % TMAH aqueous solution at 23° C. for 80 seconds.

[0316] In the resist film obtained from the chemically amplified positive resist composition of the present invention, the dissolution rate of the exposed portion in an alkaline developer is preferably 50 nm / sec or more, more preferably 80 nm / sec or more, from the viewpoint of improving development loading. By being 50 nm / sec or more, even if there are differences in pattern layout in a dense / non-dense pattern, it can be uniformly dissolved in the alkaline developer, and line width variation can be reduced. The dissolution rate of the exposed portion in the present invention is obtained by spin-coating the chemically amplified positive resist composition of the present invention on a 200 mm (8-inch) silicon wafer, baking at 110°C for 60 seconds to form a resist film with a film thickness of 90 nm, exposing with KrF excimer laser light at an energy amount at which the deprotection reaction of the polymer is completed, baking at 110°C for 60 seconds, and then using a resist development analyzer to calculate from the film reduction amount when developing at 23°C with a 2.38 mass% TMAH aqueous solution.

[0317] [Resist Pattern Forming Method] The resist pattern forming method of the present invention includes a step of forming a resist film on a substrate using the above-described chemically amplified positive resist composition, a step of irradiating the resist film with a pattern using high-energy rays (i.e., a step of exposing the resist film using high-energy rays), and a step of developing the resist film irradiated with the pattern using an alkaline developer.

[0318] As the substrate, for example, substrates for integrated circuit manufacturing (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflection film, etc.), or substrates for transmissive or reflective mask circuit manufacturing (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, SiON, SiONC, CoTa, NiTa, TaBN, SnO2, etc.) can be used. The chemically amplified positive resist composition is applied on the substrate by a method such as spin coating so that the film thickness becomes 0.03 to 2 μm, and this is pre-baked on a hot plate, preferably at 60 to 150°C for 1 to 20 minutes, more preferably at 80 to 140°C for 1 to 10 minutes, to form a resist film.

[0319] Next, the resist film is exposed using high-energy rays to irradiate a pattern. Examples of the high-energy rays include KrF excimer laser light, ArF excimer laser light, electron beams, or extreme ultraviolet rays with a wavelength of 3 to 15 nm. In the present invention, it is preferable to perform exposure using an electron beam.

[0320] The energy of the electron beam is irradiated so that the exposure dose is preferably 50 to 400 μC / cm 2 to form the target pattern.

[0321] In addition to the normal exposure method, in some cases, it is also possible to use an immersion method in which the space between the mask and the resist film is immersed. In that case, it is also possible to use a protective film that is insoluble in water.

[0322] Next, PEB is performed on a hot plate, preferably at 60 to 150 °C for 1 to 20 minutes, more preferably at 80 to 140 °C for 1 to 10 minutes.

[0323] Thereafter, a developer of an alkaline aqueous solution such as 0.1 to 5 mass%, preferably 2 to 3 mass% of TMAH is used, and development is preferably performed for 0.1 to 3 minutes, more preferably for 0.5 to 2 minutes, by a conventional method such as a dip method, a puddle method, or a spray method, whereby a target pattern is formed on the substrate.

[0324] The chemically amplified positive resist composition of the present invention is useful because it can form a pattern with particularly good isolated space resolution and a small LER. In addition, since it is difficult to achieve good adhesion of the resist pattern, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on a substrate having a surface with a material that is likely to cause pattern peeling or pattern collapse. As such a substrate, it is preferable that the outermost surface of the substrate is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin. That is, a substrate obtained by sputter-depositing a chromium compound containing one or more light elements selected from metallic chromium, oxygen, nitrogen, and carbon on the outermost surface, SiO, SiO x , substrates containing a tantalum compound, a molybdenum compound, a cobalt compound, a nickel compound, a tungsten compound, a tin compound in the outermost layer, etc. can be mentioned. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using a photomask blank as a substrate. At this time, the photomask blank may be a transmissive type or a reflective type. That is, a transmissive or reflective mask blank coated with the chemically amplified positive resist composition described above is preferable.

[0325] As a transmissive mask blank, a photomask blank having a light-shielding film made of a chromium-based material may be a photomask blank for a binary mask or a photomask blank for a phase shift mask. In the case of a photomask blank for a binary mask, it may have an antireflection layer and a light-shielding layer made of a chromium-based material as the light-shielding film, or all of the antireflection films on the surface layer side or only the outermost layer side of the antireflection films on the surface layer side are made of a chromium-based material, and the remaining part may be made of, for example, a silicon-based compound material that may contain a transition metal. Also, in the case of a photomask blank for a phase shift mask, a photomask blank for a phase shift mask having a chromium-based light-shielding film on the phase shift film can be targeted.

[0326] The photomask blank having a chromium-based material on the outermost layer as described above is very well-known as exemplified in JP-A-2008-026500, JP-A-2007-302873 or as prior art therein, and although detailed description is omitted, for example, when forming a light-shielding film having an antireflection layer and a light-shielding layer with a chromium-based material, the following film configurations can be used.

[0327] When forming a light-shielding film having an antireflection layer and a light-shielding layer with a chromium-based material, as the layer configuration, the antireflection layer and the light-shielding layer may be laminated in this order from the surface layer side, or may be laminated in the order of the antireflection layer, the light-shielding layer, and the antireflection layer. Further, the antireflection layer and the light-shielding layer may each be a multilayer, and between layers having different compositions, the composition may change discontinuously or may change continuously. As the chromium-based material to be used, metallic chromium and materials containing light elements such as oxygen, nitrogen, and carbon in metallic chromium are used. Specifically, metallic chromium, chromium oxide, chromium nitride, chromium carbide, oxynitride chromium, oxycarbide chromium, carbonitride chromium, oxynitride carbide chromium, etc. can be used.

[0328] The reflective mask blank includes a substrate, a multilayer reflective film formed on one main surface (front surface) of the substrate, specifically, a multilayer reflective film that reflects exposure light such as EUV light, and an absorber film formed on the multilayer reflective film, specifically, an absorber film that absorbs exposure light such as EUV light and reduces the reflectance. From the reflective mask blank (EUV reflective mask blank), a reflective mask (EUV reflective mask) having an absorber pattern (pattern of the absorber film) formed by patterning the absorber film is manufactured. The wavelength of EUV light used in EUV lithography is 13 to 14 nm, and usually, it is light having a wavelength of about 13.5 nm.

[0329] The multilayer reflective film is usually preferably provided in contact with one main surface of the substrate. However, as long as the effects of the present invention are not lost, it is also possible to provide an underlayer film between the substrate and the multilayer reflective film. The absorber film may be formed in contact with the multilayer reflective film. However, between the multilayer reflective film and the absorber film, a protective film (a protective film for the multilayer reflective film) may be provided preferably in contact with the multilayer reflective film, and more preferably in contact with both the multilayer reflective film and the absorber film. The protective film is used for protecting the multilayer reflective film during processes such as cleaning and correction. Further, the protective film preferably has a function of protecting the multilayer reflective film when patterning the absorber film by etching and preventing oxidation of the multilayer reflective film. On the other hand, under the other main surface (the back side surface) which is the surface opposite to one main surface of the substrate, preferably in contact with the other main surface, a conductive film used for electrostatically chucking a reflective mask to an exposure apparatus may be provided. Here, one main surface of the substrate is defined as the front side surface and the upper side, and the other main surface is defined as the back side surface and the lower side. However, the front and back and the upper and lower of both are defined for convenience. One main surface and the other main surface are any of the two main surfaces (film formation surfaces) of the substrate, and the front and back and the upper and lower are interchangeable. More specifically, it can be formed by the method as exemplified in JP-A-2021-139970 or as the prior art therein.

[0330] According to the resist pattern forming method of the present invention, even when a substrate (for example, a transmissive or reflective mask blank) whose outermost surface is made of a material that easily affects the resist pattern shape, such as a material containing chromium, silicon, or tantalum, is used, a pattern with high resolution and a small dimensional difference independent of pattern density, suppressing the influence of development loading and residue defects, can be obtained.

Examples

[0331] Hereinafter, the present invention will be specifically described by showing synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The copolymer composition ratio is a molar ratio, and Mw is the polystyrene-reduced weight average molecular weight measured by GPC.

[0332] [1] Synthesis of Acetal Modifier [Synthesis Example 1-1] Synthesis of Acetal Modifying Agent AC-1 [Chemical Formula]

[0333] (1) Synthesis of Intermediate In-1 Under a nitrogen atmosphere, 4-fluorophenol (250 g), potassium carbonate (370 g), and sodium iodide (33 g) were suspended in DMF (1,000 g). Then, the internal temperature was raised to 50 °C, and methallyl chloride (242 g) was added dropwise. After the addition, the internal temperature was raised to 65 °C and aged for 5 hours. After aging, the reaction solution was cooled, and water (1,500 g) was added to stop the reaction. The target product was extracted twice with toluene (1,000 g), subjected to a normal aqueous work-up, the solvent was distilled off, and then purified by distillation to obtain 344 g of Intermediate In-1 (yield 91%).

[0334] (2) Synthesis of Acetal Modifying Agent AC-1 Under a nitrogen atmosphere, Intermediate In-1 (344 g) and potassium t-butoxide (23 g) were dissolved in DMSO (350 g). The reaction solution was heated to an internal temperature of 80 °C and aged for 12 hours. After aging, the reaction solution was cooled, and water (500 g) was added to stop the reaction. The target product was extracted twice with toluene (500 g), subjected to a normal aqueous work-up, the solvent was distilled off, and then purified by distillation to obtain 321 g of the target acetal modifying agent AC-1 as a colorless oily substance (yield 94%).

[0335] The IR spectrum data and nuclear magnetic resonance spectrum ( 1 1H-NMR / DMSO-d6) results of the acetal modifying agent AC-1 are shown below. IR (D-ATR): ν = 3053, 2966, 2918, 2884, 2859, 1691, 1614, 1503, 1451, 1379, 1288, 1250, 1208, 1149, 1122, 1092, 1035, 1009, 830, 764, 547, 505, 445 cm -1 . 11H-NMR (600 MHz in DMSO-d6): δ = 7.13 (2H, m), 6.99 (2H, m), 6.34 (1H, m), 1.63 (6H, s) ppm.

[0336] [Synthesis Examples 1-2 to 1-8] Synthesis of Acetal Modifying Agents AC-2 to AC-8 Using the corresponding raw materials and known organic synthetic methods, acetal modifying agents AC-2 to AC-8 were synthesized respectively. [Chemical Formula]

[0337] [2] Synthesis of Polymer [Synthesis Example 2-1] Synthesis of Polymer P-1 To a 100 ml flask, 20 g of polyhydroxystyrene-ace naphthylene copolymer and 46.7 g of tetrahydrofuran as a solvent were added. With this reaction vessel under a nitrogen atmosphere, at around 25 °C, after adding 0.5 g of methanesulfonic acid, 4.4 g of acetal modifying agent AC-1 was added dropwise, and the reaction was carried out at room temperature for 4.5 hours. After the reaction was completed, 1.0 g of triethylamine was added, and the resulting reaction solution was added dropwise to 500 g of hexane, and the precipitated copolymer was filtered off. The filtered copolymer was washed twice with 120 g of hexane. The obtained copolymer was dissolved in a mixed solvent of 60 g of ethyl acetate and 20 g of water, and the resulting solution was transferred to a separatory funnel, 0.7 g of acetic acid was added, and a liquid separation operation was performed. The lower layer was distilled off, 20 g of water and 0.9 g of pyridine were added to the obtained organic layer, and a liquid separation operation was performed. The lower layer was distilled off, and further 20 g of water was added to the obtained organic layer for washing and liquid separation (washing and liquid separation were carried out 5 times in total). After liquid separation, the organic layer was concentrated, dissolved in 40 g of PGME, and the resulting solution was added dropwise to 600 g of water, and the obtained crystalline precipitate was filtered, washed with water, and dried to obtain 20.3 g of the target polymer P-1, which is a white polymer. Polymer P-1 was 13 13C-NMR, 1 When measured by 1H-NMR and GPC, the following analysis results were obtained. [Chemical Formula]

[0338] Except for changing the types and mixing ratios of the monomers, polymers P-2 to P-15, AP-1 to AP-6, and comparative polymers cP-1 to cP-6 shown below were synthesized in the same manner as in Synthesis Example 2-1 and known methods.

[0339]

Chemical formula

[0340]

Chemical formula

[0341]

Chemical formula

[0342]

Chemical formula

[0343] The dissolution rate of the polymer in the alkaline developer was measured and calculated as follows: A polymer solution (polymer concentration: 16.7% by mass, solvent: PGMEA) was spin-coated on an 8-inch silicon wafer, baked at 100 °C for 90 seconds to form a film with a thickness of 1,000 nm, and then developed with a 2.38% by mass aqueous TMAH solution at 23 °C for 100 seconds, and the film thickness reduction was measured. As a result, the dissolution rates of polymers P-1 to P-15, AP-1 to AP-6, and cP-2 to cP-6 were 5 nm / min or less, and the dissolution rate of comparative polymer cP-1 was 14 nm / min.

[0344] [3] Preparation of chemically amplified positive resist composition [Examples 1-1 to 1-41, Comparative Examples 1-1 to 1-10] Each component was dissolved in an organic solvent with the compositions shown in Tables 1 to 3 below, and the resulting solution was filtered through a nylon filter with a size of 5 nm and a UPE filter with a size of 1 nm to prepare a chemically amplified positive resist composition. The organic solvent is a mixed solvent of 940 parts by mass of PGMEA, 1,870 parts by mass of EL, and 1,870 parts by mass of PGME.

[0345]

Table 1

[0346]

Table 2

[0347]

Table 3

[0348] In Tables 1 to 3, the structures of photoacid generators PAG-1 to PAG-5, quenchers Q-1 to Q-4, and fluorine atom-containing polymers D-1 to D-5 are as follows.

[0349]

Chemical formula

[0350]

Chemical formula

[0351]

Chemical formula

[0352] [4] EB Lithography Evaluation [Examples 2-1 to 2-41, Comparative Examples 2-1 to 2-10] Each chemically amplified positive resist composition (R-1 to R-41, CR-1 to CR-10) was spin-coated onto a mask blank formed on a low thermal expansion glass substrate with a side length of 150 mm (6 inches) as a reflective mask blank for EUV exposure mask using ACT-M (manufactured by Tokyo Electron Limited), which had a 284-nm-thick Mo / Si 40-layer multilayer reflective film, a 3.5-nm-thick Ru film as a protective film thereon, a 70-nm-thick TaN film as an absorption layer thereon, and a 6-nm-thick CrN film as a hard mask thereon. The resist film with a thickness of 80 nm was fabricated by prebaking on a hot plate at 110 °C for 600 seconds. The film thickness of the obtained resist film was measured using an optical measuring instrument, Nanoscope (manufactured by Nanometrics, Inc.). The measurement was performed at 81 in-plane locations of the blank substrate excluding the outer edge portion from the outer periphery to 10 mm inside, and the film thickness average value and the film thickness range were calculated.

[0353] Furthermore, exposure was carried out using an electron beam exposure apparatus (EBM-5000plus manufactured by NuFlare Technology Inc., acceleration voltage 50 kV), PEB was performed at 110 °C for 600 seconds, and development was carried out with a 2.38 mass% TMAH aqueous solution to obtain a positive pattern.

[0354] The obtained resist pattern was evaluated as follows. The fabricated mask blank with the pattern was observed with an aerial SEM (scanning electron microscope), and the exposure dose for resolving a 200-nm 1:1 line and space (LS) at 1:1 was defined as the optimum exposure dose (μC / cm 2 ), the minimum dimension at the exposure dose for resolving a 200-nm isolated space at 9:1 was defined as the resolution (limit IS resolvability), and the LER of 200-nm LS was measured with an SEM. For the development loading evaluation, on the substrate surface, the space portion dimensions of a 200-nm LS pattern formed at the exposure dose (μC / cm 2 ) for resolving a 200-nm 1:1 LS at a 1:1 ratio and a 200-nm LS pattern with dummy patterns having densities of 15%, 25%, 33%, 45%, 50%, 55%, 66%, 75%, 85%, and 95% arranged around the pattern were measured with an SEM, and the dense and sparse pattern dimension differences were compared. Regarding the pattern shape, it was visually determined whether it was rectangular or not.

[0355] The dissolution rate of the exposed area was determined by spin-coating a resist solution on a 200 mm (8-inch) silicon wafer, baking it at 110 °C for 60 seconds to form a resist film with a thickness of 90 nm, and then exposing it with KrF excimer laser light at an exposure dose (mJ / cm 2 ) that resolves a 1:1 line-and-space (LS) pattern of 200 nm at a 1:1 ratio. After baking at 110 °C for 60 seconds, development was carried out at 23 °C using a 2.38 mass% TMAH aqueous solution with a resist development analyzer (RDA-800 manufactured by Resotec Japan Co., Ltd.). The results are shown in Tables 4 to 6.

[0356]

Table 4

[0357]

Table 5

[0358]

Table 6

[0359] [5] Residual defect evaluation [Examples 3-1 to 3-41, Comparative Examples 3-1 to 3-10] Substrates coated with resist compositions (R-1 to R-41, CR-1 to CR-10) on a reflective mask blank for EUV exposure were entirely drawn at the optimum exposure dose of each resist composition using an electron beam exposure apparatus (EBM-5000plus manufactured by NuFlare Technology Inc., acceleration voltage 50 keV), subjected to PEB at 110 °C for 600 seconds, developed with a 2.38 mass% TMAH aqueous solution, and the developed residues were evaluated with a mask defect inspection apparatus (M9650 manufactured by Lasertec Corporation). The total number of defects after development is shown in Table 7.

[0360]

Table 7

[0361] As shown in Tables 4 to 7, the chemically amplified positive resist compositions (R-1 to R-41) of the present invention all exhibited good isolated space (IS) resolution, LER, and pattern rectangularity compared to the resist compositions (CR-1 to CR-10) of the comparative examples, and showed values with suppressed development loading and total number of defects after development.

[0362] [6] Dry etching resistance evaluation [Examples 4-1 to 4-41, Comparative Examples 4-1 to 4-10] Resist compositions (R-1 to R-41, CR-1 to CR-10) in which 2 g of each component were dissolved in 10 g of cyclohexanone with the compositions shown in Tables 1 to 3 and filtered through a 0.2 μm size filter were spin-coated onto a mask blank with a 152 mm square top surface of Cr film to form a film with a thickness of 300 nm and evaluated under the following conditions. Etching test with chlorine-based gas: Using a plasma thermo mask dry etching apparatus Gen-4, the film thickness difference of the polymer film before and after etching was determined. The etching conditions are as shown below. Chamber pressure 6.0 mTorr RF power 700 V Cl2 gas flow rate 185 sccm O2 flow rate 55 sccm He flow rate 9 sccm Time 75 sec In this evaluation, those with a small film thickness difference, that is, those with a small reduction amount, indicate resistance to etching. The results of the dry etching resistance evaluation are shown in Table 8.

[0363]

Table 8

[0364] From the results shown in Table 8, it was confirmed that the chemically amplified positive resist compositions (R-1 to R-41) containing the polymer of the present invention have excellent dry etching resistance in Cl2 / O2-based gases.

[0365] From the above results, the polymer of the present invention, the chemically amplified positive resist composition using the same, the resist pattern forming method, and the mask blank using the chemically amplified positive resist composition of the present invention are useful for photolithography in the manufacture of semiconductor elements, particularly in the processing of transmissive or reflective photomask blanks.

[0366] This specification includes the following aspects. [1]: A polymer, wherein the aromatic hydroxyl group in the structural unit containing an aromatic hydroxyl group bonded to the main chain is protected by an acid-labile group represented by the following formula (ALU-1) and becomes alkali-soluble by deprotection by the action of an acid. [Chemical formula] (In formula (ALU-1), R L1 ~R L3 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms and not containing an aromatic cyclic structure. Among R L1 ~R L3 , any two of them may be bonded to each other to form a cyclic structure together with the carbon atom to which they are bonded. R L4 is a hydrogen atom, a halogen atom, a nitro group, or a hydrocarbyl group having 1 to 6 carbon atoms which may contain a hetero atom. n1 is an integer of 0 or 1. n2 is an integer of 0 to 5 when n1 = 0, and an integer of 0 to 7 when n1 = 1. The broken line represents the bond with the oxygen atom of the aromatic hydroxyl group of the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer.) [2]: The polymer according to [1] above, wherein the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer is a repeating unit represented by the following formula (A1). [Chemical formula] (In formula (A1), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 1is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond with a carbon atom in the main chain. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. X 2 is any one of a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond and a carbamate bond. R B is a halogen atom, or a linear, branched or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. n1 is the same as described above. n3 is an integer of 0 to 4 when n1 = 0, and an integer of 0 to 6 when n1 = 1. n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≦ 5, and when n1 = 1, n3 + n4 ≦ 7. The broken line represents a bond with the formula (ALU-1).) [3]: The polymer according to [1] or [2] above, characterized in that the polymer further contains a repeating unit containing a phenolic hydroxy group represented by the following formula (A2). [Chemical formula] (In the formula (A2), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 1 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond with a carbon atom in the main chain. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. X 2 is any one of a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond and a carbamate bond. R Bis a linear, branched or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a hetero atom. n1 is the same as described above. n3 is an integer of 0 to 4 when n1 = 0, and an integer of 0 to 6 when n1 = 1. n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≤ 5, and when n1 = 1, n3 + n4 ≤ 7.) [4]: The polymer according to the above [3], wherein the phenolic hydroxy group-containing repeating unit is a repeating unit represented by the following formula (A2-1). [Chemical formula] (In formula (A2-1), R A is the same as described above. b’ is an integer of 1 to 3.) [5]: The polymer according to any one of the above [1] to [4], wherein the polymer further contains one or more repeating units represented by any of the following formulas (B1) to (B3). [Chemical formula] (In the formula, R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. b and c are each independently an integer of 0 to 4. d is an integer of 0 to 5. e is an integer of 0 to 2. X 3 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom of the main chain. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. R 11 and R 12 are each independently a hydroxy group, a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom. R 13is an acetyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group or a cyano group, and when e is 1 or 2, it may also be a hydroxy group.) [6]: The polymer is characterized in that it further contains a repeating unit represented by the following formula (A3-1) and / or the following formula (A3-2), which is the polymer according to any one of [1] to [5] above.

Chemical formula

Chemical formula

[10] : Further, the chemically amplified positive resist composition of [8] or [9] above, which is characterized by containing a photoacid generator whose conjugate acid of the anion has an acid strength (pKa) of -2.0 or more.

[11] : The chemically amplified positive resist composition of

[10] above, which is characterized by containing, as the photoacid generator, an anion structure of a photoacid generator represented by the following formula (M-1). [Chemical formula] (In formula (M-1), m is 0 or 1. p is an integer from 1 to 3. q is an integer from 1 to 5. r is an integer from 0 to 3. L 1 is a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. L 2 is an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. X 4 is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms when p is 1, and a (p + 1)-valent hydrocarbon group having 1 to 20 carbon atoms when p is 2 or 3. The hydrocarbylene group and the (p + 1)-valent hydrocarbon group may contain at least one 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. Rf 1 and Rf 2 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. R 21 is a hydroxy group, a carboxy group, 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, a fluorine atom, a chlorine atom, a bromine atom, an amino group, -N(R 1A )-C(=O)-R 1B or -N(R 1A )-C(=O)-O-R 1B and R1A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R 1B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 22 is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms. Part or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and part or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, and a hydroxy group.)

[12] : Further, the chemically amplified positive resist composition according to any one of [8] to

[11] above, which comprises a quencher.

[13] : Further, the chemically amplified positive resist composition according to any one of [8] to

[12] above, which comprises at least one selected from a repeating unit represented by the following formula (D1), a repeating unit represented by the following formula (D2), a repeating unit represented by the following formula (D3), and a repeating unit represented by the following formula (D4), and which comprises a fluorine atom-containing polymer. [Chemical formula] (In the formula, R B are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid-labile group, and R 103 , R 106 , R 107 and R 108When it is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. m' is an integer of 1 to 3. Z 1 is a (m'+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (m'+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.)

[14] : The fluorine atom-containing polymer further contains at least one selected from the repeating unit represented by the following formula (D5) and the repeating unit represented by the following formula (D6), and the chemically amplified positive resist composition according to the above

[13] .

Chemical formula

[15] : The chemically amplified positive resist composition according to any one of [8] to

[14] above, wherein the dissolution rate of the polymer in an alkaline developer is 10 nm / min or less.

[16] : The chemically amplified positive resist composition according to any one of [8] to

[14] above, wherein the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less.

[17] : The chemically amplified positive resist composition according to any one of [8] to

[14] above, wherein the dissolution rate of the exposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 50 nm / sec or more.

[18] : A resist pattern forming method comprising a step of forming a resist film on a substrate using the chemically amplified positive resist composition according to any one of [8] to

[17] above, a step of irradiating the resist film with a high-energy ray to form a pattern, and a step of developing the resist film irradiated with the pattern using an alkaline developer.

[19] : The resist pattern forming method according to

[18] above, wherein the high-energy ray is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

[20] : The resist pattern forming method according to

[18] or

[19] above, wherein the outermost surface of the substrate is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin.

[21] : The resist pattern forming method according to

[20] above, wherein a transmissive or reflective mask blank is used as the substrate.

[22] : A transmissive or reflective mask blank coated with the chemically amplified positive resist composition according to any one of [8] to

[17] above.

[0367] Note that the present invention is not limited to the above-described embodiments. The above-described embodiments are examples, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Claims

1. A polymer, comprising a structural unit containing an aromatic hydroxyl group bonded to the main chain, a repeating unit containing a phenolic hydroxyl group represented by the following formula (A2), and one or more repeating units represented by any of the following formulas (B1), (B2), and (A3-2), not containing a repeating unit represented by any of the following formulas (C1) to (C8), and having an aromatic ring skeleton in all units, wherein the aromatic hydroxyl group in the structural unit containing an aromatic hydroxyl group bonded to the main chain is protected by an acid-labile group represented by the following formula (ALU-1) and is deprotected by the action of an acid to become alkali-soluble. 【Chemical 1】 (In formula (ALU-1), R Ｌ１ to R Ｌ３ are each independently a hydrogen atom or a hydrocarbyl group having 1 to 6 carbon atoms and not containing an aromatic ring structure. Among R Ｌ１ to R Ｌ３ , any two of them may be bonded to each other to form a cyclic structure together with the carbon atoms to which they are bonded. R Ｌ４ is a hydrogen atom, a halogen atom, a nitro group, or a hydrocarbyl group having 1 to 6 carbon atoms which may contain a hetero atom. n1 is an integer of 0 or 1. n2 is an integer of 0 to 5 when n1 = 0, and an integer of 0 to 7 when n1 = 1. The dashed line represents the bond with the oxygen atom of the aromatic hydroxyl group of the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer.) 【Chemical Formula 2】 (In formula (A2), each RA is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X1 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom of the main chain. A1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. X2 is any of a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond, and a carbamate bond. RB is a halogen atom, or a linear, branched, or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. n1 is the same as above. n3 is an integer of 0 to 4 when n1 = 0, and an integer of 0 to 6 when n1 = 1. n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≦ 5, and when n1 = 1, n3 + n4 ≦ 7.) 【Chemical Formula 3】 (In the formula, b and c are each independently an integer of 0 to 4. R11 and R12 are each independently a hydroxyl group, a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom.) [Chemical Formula 4] (In formula (A3-2), c1 is an integer from 0 to 2. c2 is an integer from 0 to 2. c3 is an integer from 0 to 5. c4 is an integer from 0 to 2. Each RA is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A4 is a single bond, a phenylene group, a naphthylene group or *-C(=O)-O-A41-. A41 is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or a naphthylene group. R'13 and R'14 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hetero atom, and R'13 and R'14 may combine with each other to form a ring together with the carbon atom to which they are attached. R'15 is each independently a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms or a fluorinated alkoxy group having 1 to 5 carbon atoms. R'16 is each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a hetero atom.) 【Chemical Formula 5】 (In the formula, each R A is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y 1 is 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-Y 11 -, *-C(=O)-O-Y 11 -, or *-C(=O)-NH-Y 11 -, where Y 11 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. Y 2 is a single bond or **-Y 21 -C(=O)-O-, where Y 21 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a hetero atom. Y 3 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-O-Y 31 -, *-C(=O)-O-Y 31 -, or *-C(=O)-NH-Y 31 -, where Y 31 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, or a group having 7 to 20 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. * is a bond to a carbon atom of the main chain, and ** is a bond to an oxygen atom in the formula. Y 4 is a single bond or a hydrocarbylene group having 1 to 30 carbon atoms which may contain a hetero atom. k 1 and k 2 are each independently 0 or 1, provided that when Y 4 is a single bond, k 1 and k 2 are 0. R 51 to R 68 are each independently a halogen atom, or a hydrocarbyl group having 1 to 25 carbon atoms which may contain a hetero atom. Further, R 51 and R 52 may combine with each other to form a ring together with the sulfur atom to which they are attached, and R 53 and R 54, R 56 and R 57, and R 59 and R 60 may each combine with each other to form a ring together with the sulfur atom to which they are attached. R HF is a hydrogen atom or a trifluoromethyl group. Xa - is a non-nucleophilic counter ion.)

2. The polymer according to claim 1, wherein the unit containing the aromatic hydroxyl group bonded to the main chain of the polymer is a repeating unit represented by the following formula (A1). [Chemical Formula 6] (In formula (A1), R Ａ is each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X １ is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to a carbon atom of the main chain. A １ is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH ２ - constituting the saturated hydrocarbylene group may be substituted with -O-. X ２ is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonic acid ester bond, a carbonate bond, or a carbamate bond. R Ｂ is a halogen atom, or a linear, branched, or cyclic hydrocarbyl group having 1 to 20 carbon atoms which may contain a hetero atom. n1 is the same as described above. n3 is an integer of 0 to 4 when n1 = 0, and an integer of 0 to 6 when n1 = 1. n4 is an integer of 1 to 3. However, when n1 = 0, n3 + n4 ≤ 5, and when n1 = 1, n3 + n4 ≤ 7. The dashed line represents a bond to the formula (ALU-1).)

3. The polymer according to claim 1, wherein the repeating unit containing a phenolic hydroxyl group is a repeating unit represented by the following formula (A2-1). 【Chemical Formula 7】 (In formula (A2-1), R Ａ is the same as described above. b' is an integer of 1 to 3.)

4. A chemically amplified positive resist composition comprising the polymer according to any one of claims 1 to 3.

5. The chemically amplified positive resist composition according to claim 4, further comprising an organic solvent.

6. The chemically amplified positive resist composition according to claim 4, further comprising a photoacid generator having an acid strength (pKa) of the conjugate acid of the anion of -2.0 or more.

7. The chemically amplified positive resist composition according to claim 6, wherein the photoacid generator contains an anion structure of a photoacid generator represented by the following formula (M-1). 【Chemical 8】 (In formula (M-1), m is 0 or 1. p is an integer from 1 to 3. q is an integer from 1 to 5. r is an integer from 0 to 3. L １ is a single bond, an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. L ２ is an ether bond, an ester bond, a sulfonic acid ester bond, a carbonate bond or a carbamate bond. X ４ is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms when p is 1, and a (p+1)-valent hydrocarbon group having 1 to 20 carbon atoms when p is 2 or 3. The hydrocarbylene group and the (p+1)-valent hydrocarbon group may contain at least one 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. Rf １ and Rf ２ are each independently a hydrogen atom, a fluorine atom or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group. R ２１ is a hydroxy group, a carboxy group, 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, a fluorine atom, a chlorine atom, a bromine atom, an amino group, -N(R １Ａ )-C(=O)-R １Ｂ or -N(R １Ａ )-C(=O)-O-R １Ｂ wherein R １Ａ is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and R １Ｂ is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R ２２ is a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 14 carbon atoms, and part or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and part or all of the hydrogen atoms of the arylene group may be substituted with substituents selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, and a hydroxy group.)

8. The chemically amplified positive resist composition according to claim 4, further comprising a quencher.

9. The chemically amplified positive resist composition according to claim 4, further comprising at least one selected from the repeating unit represented by the following formula (D1), the repeating unit represented by the following formula (D2), the repeating unit represented by the following formula (D3), and the repeating unit represented by the following formula (D4), and containing a fluorine atom-containing polymer. 【Chemical Formula 9】 (In the formula, R Ｂ is independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R １０１ , R １０２ , R １０４ and R １０５ are independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R １０３ , R １０６ , R １０７ and R １０８ are independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms or an acid-labile group, and when R １０３ , R １０６ , R １０７ and R １０８ are a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between carbon-carbon bonds. m' is an integer of 1 to 3. Z １ is a (m'+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (m'+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.)

10. The chemically amplified positive resist composition according to claim 9, wherein the fluorine atom-containing polymer further contains at least one selected from the repeating unit represented by the following formula (D5) and the repeating unit represented by the following formula (D6). 【Chemical Formula 10】 (wherein R Ｃ is, independently of one another, a hydrogen atom or a methyl group. R １０９ is a hydrogen atom, or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group intervening between carbon-carbon bonds. R １１０ is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group intervening between carbon-carbon bonds. R １１１ is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a part of -CH ２ - constituting the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. x is an integer of 1 to 3. y is an integer satisfying 0 ≦ y ≦ 5 + 2z - x. z is 0 or 1. Z ２ is a single bond, *-C(=O)-O- or *-C(=O)-NH-. Z ３ is a single bond, -O-, *-C(=O)-O-Z ３１ -Z ３２ - or *-C(=O)-NH-Z ３１ -Z ３２ -. Z ３１ is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. Z ３２ is a single bond, an ester bond, an ether bond or a sulfonamide bond. * is a bond to a carbon atom of the main chain.)

11. The chemically amplified positive resist composition according to claim 4, wherein the dissolution rate of the polymer in an alkaline developer is 10 nm / min or less.

12. The chemically amplified positive resist composition according to claim 4, wherein the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less.

13. The chemically amplified positive resist composition according to claim 4, wherein the dissolution rate of the resist film obtained from the chemically amplified positive resist composition in an alkaline developer in the exposed area is 50 nm / sec or more.

14. A resist pattern forming method comprising a step of forming a resist film on a substrate using the chemically amplified positive resist composition according to claim 4, a step of irradiating the resist film with a high-energy ray to form a pattern, and a step of developing the resist film irradiated with the pattern using an alkaline developer.

15. The resist pattern forming method according to claim 14, wherein the high-energy ray is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

16. The resist pattern forming method according to claim 14, wherein the outermost surface of the substrate is made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin.

17. The resist pattern forming method according to claim 16, wherein a transmissive or reflective mask blank is used as the substrate.

18. A transmissive or reflective mask blank coated with the chemically amplified positive resist composition according to claim 4.

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