Chemically amplified positive-type resist composition and resist pattern formation method

Abstract

To provide a chemically amplified positive resist composition capable of forming a resist film which can form a pattern having extremely high resolution, small LER and excellent rectangularity and capable forming a pattern with suppressed influence of development loading and to provide a resist patterning method using the chemically amplified positive resist composition.SOLUTION: There is provided a chemically amplified positive resist composition comprising a base polymer which contains a polymer comprising a phenolic hydroxy group-containing unit, a unit containing a phenolic hydroxy group protected with an acid unstable group and a unit containing a carboxy group protected with an acid unstable group or a polymer comprising a phenolic hydroxy group-containing unit and a unit containing a phenolic hydroxy group protected with an acid unstable group and a polymer comprising a phenolic hydroxy group-containing unit and a unit containing a carboxy group protected with an acid unstable group, wherein the repeating units having an aromatic ring skeleton in the total repeating units of the polymer contained in the base polymer is 65 mol% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a chemically amplified positive-type resist composition and a resist pattern formation method. [Background technology]

[0002] In recent years, with the increasing integration of integrated circuits, there has been a demand for the formation of finer patterns. For processing patterns of 0.2 μm or less, chemically amplified resist compositions using acids as catalysts are mainly used. High-energy rays such as ultraviolet light, far ultraviolet light, extreme ultraviolet (EUV), and electron beams (EB) are used as exposure sources in this process. EB lithography, in particular, which is used as an ultra-fine processing technology, has become indispensable as a method for processing photomask blanks when creating photomasks for semiconductor manufacturing.

[0003] Generally, in EB lithography, EB drawing is performed without the use of a mask. In the case of positive-type lithography, micro-area EB is sequentially irradiated onto areas of the resist film other than those to be preserved, while in the case of negative-type lithography, micro-area EB is sequentially irradiated onto areas of the resist film to be preserved. In other words, because the entire area of ​​the processed surface is swept across the finely divided sections, it takes longer than batch exposure using a photomask, and a highly sensitive resist film is required to maintain throughput. Particularly in the processing of photomask blanks, which is an important application, some photomask substrates have surface materials such as chromium oxide and other chromium compound films that can easily affect the pattern shape of the chemically amplified resist film. Therefore, maintaining a rectangular pattern profile of the resist film, regardless of the substrate type, is considered an important performance characteristic in order to maintain high resolution and shape after etching. Another important performance characteristic is a low line edge roughness (LER).

[0004] Various improvements have been made to control sensitivity and pattern profiles through the selection and combination of materials used in the resist composition, process conditions, and other factors. One such improvement is the suppression of acid diffusion, which has a significant impact on the resolution of the resist film. In photomask processing, it is required that the shape of the resulting resist pattern does not change depending on the time between exposure and heating. A major cause of time-dependent changes in the resist pattern shape is the diffusion of acid generated by exposure. This acid diffusion problem has been investigated extensively, not only in photomask processing but also in general resist compositions, as it significantly affects sensitivity and resolution.

[0005] Patent documents 1 and 2 describe examples of reducing LER by increasing the bulk of the acid generated from an acid generator to suppress acid diffusion. However, since the suppression of acid diffusion with such acid generators is still insufficient, there has been a need for the development of an acid generator that exhibits even less acid diffusion.

[0006] Furthermore, Patent Document 3 describes an example of controlling acid diffusion by introducing repeating units having a sulfonium structure that generates sulfonic acid upon exposure into a polymer used in a resist composition. This method of suppressing acid diffusion by introducing repeating units that generate acid upon exposure into a base polymer is effective in obtaining a pattern with a small LER. However, in some cases, base polymers containing such repeating units that generate acid upon exposure may have problems with solubility in organic solvents, depending on the structure and introduction rate of the units.

[0007] Polymers containing a large amount of aromatic skeletons with acidic side chains, such as polyhydroxystyrene, are useful as base polymers for KrF lithography resist compositions. However, they exhibit significant absorption for light around 200 nm, and therefore have not been used as base polymers for ArF lithography resist compositions. Nevertheless, they are important materials for EB lithography resist compositions and EUV lithography resist compositions, which are promising techniques for forming patterns smaller than the processing limit of ArF excimer laser light, due to their high etching resistance.

[0008] For positive-type EB lithography resist compositions and EUV lithography resist compositions, the base polymers mainly used are those that can be solubilized in an alkaline developer by using an acid generated by irradiating a photoacid generator with high-energy rays as a catalyst to deprotect the acid-unstable groups that mask the acidic functional groups of the phenol side chains of the base polymer. In addition, tertiary alkyl groups, tert-butoxycarbonyl groups, and acetal groups have been mainly used as the acid-unstable groups. Here, while using acid-unstable groups such as acetal groups, which require relatively low activation energy for deprotection, has the advantage of obtaining a highly sensitive resist film, if the diffusion of the generated acid is not sufficiently suppressed, the deprotection reaction will occur even in the unexposed parts of the resist film, leading to a deterioration of resolution and LER.

[0009] On the other hand, in the development process of photomask manufacturing, a phenomenon called development loading occurs, in which there are differences in the dimensional finish of the pattern between dense and sparse areas on the photomask. In other words, development loading causes an uneven distribution of the dimensional finish of the pattern depending on the pattern distribution of the surrounding area. Factors contributing to this include differences in the desorption reaction during acid generation due to the energy difference of the electroluminescent beam (EB), and differences in the dissolution rate of the dense and sparse patterned areas in the alkaline developer. As one improvement, Patent Document 4 describes a method of adjusting the incident dose amount in the EB writing apparatus to irradiate with EB and draw a pattern on the photomask in order to correct for development loading. However, conventional correction methods did not adequately consider the phenomenon of development loading. Therefore, conventional correction methods had poor accuracy in correcting for development loading. To solve this, methods for drawing resist films and methods for improving the development method after patterning, as described in Patent Documents 5 and 6, have been developed, but these are insufficient for uniformly distributing dense and sparse fine patterns in the advanced generation, and improvements to the resist composition have been desired. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2009-053518 [Patent Document 2] Japanese Patent Publication No. 2010-100604 [Patent Document 3] Japanese Patent Publication No. 2011-22564 [Patent Document 4] Japanese Patent Publication No. 2007-150243 [Patent Document 5] Patent No. 5443548 [Patent Document 6] Patent No. 6281244 [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention has been made in view of the above circumstances, and aims to provide a chemically amplified positive-type resist composition that can form a resist film having extremely high resolution, low LER, excellent rectangularity, and the ability to form a pattern that suppresses the effects of development loading, and a method for forming a resist pattern using the chemically amplified positive-type resist composition. [Means for solving the problem]

[0012] As a result of diligent research to achieve the above objective, the inventors of the present invention discovered that by introducing a base polymer having a specific structure into a resist composition, a pattern exhibiting good resolution, pattern shape, and LER, and suppressing the effects of development loading, can be obtained, leading to the present invention.

[0013] In other words, the present invention provides the following chemically amplified positive-type resist composition and resist pattern formation method. 1. A chemically amplified positive-type resist composition comprising a base polymer protected by an acid-unstable group and becoming alkali-soluble upon the action of an acid, The base polymer comprises a polymer containing a phenolic hydroxyl group-containing unit, a unit in which the phenolic hydroxyl group is protected by an acid-unstable group, and a unit in which the carboxyl group is protected by an acid-unstable group, or a polymer containing a phenolic hydroxyl group-containing unit and a unit in which the phenolic hydroxyl group is protected by an acid-unstable group, and a polymer containing a phenolic hydroxyl group-containing unit and a unit in which the carboxyl group is protected by an acid-unstable group. The phenolic hydroxyl group-containing unit is a repeating unit represented by the following formula (A1), the unit in which the phenolic hydroxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A2), and the unit in which the carboxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A3), A chemically amplified positive-type resist composition wherein 65 mol% or more of the total repeating units of the polymer contained in the base polymer have an aromatic ring skeleton. [ka] (In the formula, a is an integer satisfying 0 ≦ a ≦ 5 + 2c - b. b is an integer from 1 to 3. c is an integer from 0 to 2.) R A is 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 -CH2- constituting the saturated hydrocarbylene group may be substituted with -O-. R 1 is 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 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom.) [Chemical formula] (In the formula, R A is the same as above. d is an integer satisfying 0 ≦ d ≦ 5 + 2f - e. e is an integer from 1 to 3. f is an integer from 0 to 2.) X 2 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 2 is 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 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom.) R 3When e is 1, it is an acid-unstable group; when e is 2 or more, it is a hydrogen atom or an acid-unstable group, but at least one of them is an acid-unstable group. [ka] (In the formula, R A The same applies as above. X 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OX 3A - and X 3A This is a saturated hydrocarbylene group having 1 to 20 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. * indicates a bond with a carbon atom of the main chain. R 4 It is an acid-unstable group. 2. A chemically amplified positive resist composition wherein the phenolic hydroxyl group-containing unit is a repeating unit represented by the following formula (A1-1). [ka] (In the formula, R A (and b are the same as above.) 3. A chemically amplified positive resist composition of type 1 or 2, wherein the unit in which the phenolic hydroxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A2-1). [ka] (In the formula, R A This is the same as above. R 5 This is an acid-unstable group having an aromatic hydrocarbon group with 6 to 20 carbon atoms and / or an alicyclic hydrocarbon group with 5 to 20 carbon atoms. 4. A chemically amplified positive resist composition of any of 1 to 3, wherein the unit in which the carboxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A3-1). [ka] (In the formula, R A and X 3This is the same as above. R 6 This is an acid-unstable group having an aromatic hydrocarbon group with 6 to 20 carbon atoms and / or an alicyclic hydrocarbon group with 5 to 20 carbon atoms. 5. A chemically amplified positive resist composition of any of 1 to 3, wherein the unit in which the carboxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A3-2). [ka] (In the formula, R A and X 3 The same applies as above. R B and R C Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms, and R B and R C These elements may bond with each other to form a ring with the carbon atoms to which they are bonded. R 7 Each of these is 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 8 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms. n1 is either 1 or 2. n2 is an integer between 0 and 5. n3 is an integer between 0 and 2. 6. A chemically amplified positive resist composition of type 5, wherein the repeating unit represented by formula (A3-2) is represented by the following formula (A3-3). [ka] (In the formula, R A , R B , R C , X 3 , R 7 , R 8 (n1 and n2 are the same as above.) 7.R 7 A chemically amplified positive resist composition of 5 or 6, wherein the resist is a fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group. 8. A chemically amplified positive resist composition of any of 1 to 7, wherein the polymer contained in the base polymer further contains repeating units represented by any of the following formulas (B1) to (B3). [ka] (In the formula, R A The same applies as above. g and h are independent integers between 0 and 4. i is an integer between 0 and 5. j is an integer between 0 and 2. R 11 and R 12 These are, independently, a hydroxyl group, a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom. R 13 This group 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. If j is 1 or 2, it may also be a hydroxyl group. X 4 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. A 3 (This refers to a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, where some of the -CH2- groups constituting the saturated hydrocarbylene group may be substituted with -O- groups.) 9. A chemically amplified positive resist composition wherein the sum of repeating units represented by formula (A1) and any of the repeating units represented by formulas (B1) to (B3) is 50 mol% or more of the total repeating units of the polymer contained in the base polymer. 10. A chemically amplified positive resist composition according to any one of 1 to 9, comprising a fluorine atom-containing polymer that further comprises at least one selected from repeating units represented by the following formula (C1), repeating units represented by the following formula (C2), repeating units represented by the following formula (C3), and repeating units represented by the following formula (C4), and which may further comprise at least one selected from repeating units represented by the following formula (C5) and repeating units represented by the following formula (C6). [ka] (In the formula, R D These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R E Each of these is independently either a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 Each of these is independently either a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, or an acid-unstable group, and R 103 , R 106 , R 107 and R 108 When the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. R 109 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. R 110 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a heteroatom interposed between the carbon-carbon bonds. R 111This 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 some of the -CH2- groups constituting the saturated hydrocarbyl group may be substituted with ester bonds or ether bonds. x is an integer between 1 and 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is either 0 or 1. m is an integer between 1 and 3. Z 1 This 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. Z 2 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain. Z 3 This is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 -or *-C(=O)-NH-Z 31 -Z 32 - is Z 31 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 A is a single bond, ester bond, ether bond, or sulfonamide bond. * indicates a bond to a carbon atom in the main chain. 11. Furthermore, any of the 1 to 10 chemically amplified positive resist compositions containing an organic solvent. 12. Furthermore, any of the 1 to 10 chemically amplified positive resist compositions comprising a photoacid generator. 13. A chemically amplified positive resist composition wherein the acid strength (pKa) of the anion of the photoacid generator is -2.0 or higher. 14. A chemically amplified positive-type resist composition of any of 1 to 13, wherein the dissolution rate of the overexposed portion of the resist film obtained from the chemically amplified positive-type resist composition is 50 nm / sec or more. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using any of the chemically amplified positive-type resist compositions of 15.1 to 14; irradiating the resist film with a pattern using high-energy rays; and developing the resist film irradiated with the pattern using an alkaline developer. 16. A resist pattern formation method 15 wherein the high-energy beam is EUV or EB. 17. A resist pattern formation method 15 or 16 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. 18. A method for forming a resist pattern according to any of 15 to 17, wherein the substrate is a photomask blank. Photomask blanks coated with one of the chemically amplified positive resist compositions from 19.1 to 14. [Effects of the Invention]

[0014] The chemically amplified positive resist composition of the present invention exhibits high resolution, low LER, and enables the formation of highly rectangular patterns with good post-exposure shape and suppressed effects of development loading. It is suitable as a resist composition for forming resist films responsive to high-energy rays such as ultraviolet, far-ultraviolet, EB, EUV, X-rays, gamma rays, and synchrotron radiation used in the processing of semiconductors and photomask blanks. Furthermore, the pattern formation method using the chemically amplified positive resist composition of the present invention can form patterns with high resolution, etching resistance, reduced LER, and suppressed effects of development loading, making it suitable for use in microfabrication technologies, particularly EUV lithography and EB lithography. [Modes for carrying out the invention]

[0015] The present invention will be described in detail below. In the following description, depending on the structure represented by the chemical formula, an asymmetric carbon may be present, and enantiomers or diastereomers may exist. In such cases, a single formula will represent all of these isomers. These isomers may be used individually or as a mixture.

[0016] [Chemically amplified positive-type resist composition] The chemically amplified positive resist composition of the present invention comprises a base polymer protected by acid-unstable groups and becoming alkali-soluble upon the action of an acid.

[0017] The base polymer comprises a polymer containing a phenolic hydroxyl group-containing unit, a unit in which the phenolic hydroxyl group is protected by an acid-unstable group, and a unit in which the carboxyl group is protected by an acid-unstable group; or a polymer containing a phenolic hydroxyl group-containing unit and a unit in which the phenolic hydroxyl group is protected by an acid-unstable group, and a polymer containing a phenolic hydroxyl group-containing unit and a unit in which the carboxyl group is protected by an acid-unstable group.

[0018] The aforementioned phenolic hydroxyl group-containing unit is a repeating unit represented by the following formula (A1) (hereinafter also referred to as repeating unit A1). [ka]

[0019] In equation (A1), a is an integer satisfying 0 ≤ a ≤ 5 + 2c - b. b is an integer between 1 and 3. c is an integer between 0 and 2.

[0020] In formula (A1), R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0021] In formula (A1), X 1 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain.

[0022] In formula (A1), A 1The saturated hydrocarbylene group is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- groups constituting the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples include alkanediyl groups having 1 to 10 carbon atoms such as methylene groups, ethane-1,2-diyl groups, propane-1,3-diyl groups, butane-1,4-diyl groups, pentane-1,5-diyl groups, hexane-1,6-diyl groups, and their structural isomers; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms such as cyclopropanediyl groups, cyclobutanediyl groups, cyclopentanediyl groups, and cyclohexanediyl groups; and groups obtained by combining these.

[0023] In formula (A1), R 1 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, and the saturated hydrocarbyl portion of the saturated hydrocarbyl carbonyloxy group and saturated hydrocarbyloxy group may be linear, branched, or cyclic. Specific examples include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, and hexyl groups; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups; and groups obtained by combining these. If the number of carbon atoms is below the upper limit, the solubility in alkaline developer is good. When a is 2 or more, each R 1 They may be the same as or different from each other.

[0024] X 1 and A 1When both are single bonds, preferred examples of repeating unit A1 include units derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, etc. Of these, repeating units represented by the following formula (A1-1) are more preferred. [ka] (In the formula, R A (and b are the same as above.)

[0025] X 1 When the bond is not a single bond, preferred examples of the repeating unit A1 are, but are not limited to, those shown below. Note that in the following formula, R A This is the same as described above. [ka]

[0026] [ka]

[0027] The repeating unit A1 is preferably introduced in an amount of 10 to 95 mol%, and more preferably in an amount of 30 to 85 mol%, of the total repeating units of the polymer contained in the base polymer. However, if the polymer described later includes at least one of the repeating units represented by formula (B1) and formula (B2) that provide high etching resistance, and the unit has a phenolic hydroxyl group as a substituent, then it is preferable that the ratio of this unit is also included within the above range. The repeating unit A1 may be used alone or in combination of two or more types.

[0028] The unit in which the phenolic hydroxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A2) (hereinafter also referred to as repeating unit A2). [ka]

[0029] In formula (A2), R A The same applies as above. d is an integer satisfying 0 ≤ d ≤ 5 + 2f - e. e is an integer between 1 and 3. f is an integer between 0 and 2.

[0030] In formula (A2), X 2 A is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain.

[0031] In formula (A2), A 2 A is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and some of the -CH2- groups constituting the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and a specific example thereof is A in formula (A1). 1 Examples similar to those given in the explanation can be cited.

[0032] In formula (A2), R 2 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, as well as the saturated hydrocarbyl portion of the saturated hydrocarbyl carbonyloxy group and the saturated hydrocarbyl oxy group, may be linear, branched, or cyclic, and a specific example thereof is R in formula (A1). 1 Examples similar to those given in the explanation can be cited. If the number of carbon atoms is below the upper limit, solubility in alkaline developer is good. When d is 2 or more, each R 2 They may be the same as or different from each other.

[0033] In formula (A2), R 3When e is 1, it is an acid-labile group; when e is 2 or more, it is a hydrogen atom or an acid-labile group, and at least one is an acid-labile group.

[0034] The unit in which the carboxy group is protected by an acid-labile group is a repeating unit represented by the following formula (A3) (hereinafter, also referred to as repeating unit A3).

Chemical formula

[0035] In formula (A3), R A is the same as described above. X 3 is a single bond, a phenylene group, a naphthylene group or *-C(=O)-O-X 3A -, and X 3A is a hydroxy group, an ether bond, an ester bond or a saturated hydrocarbylene group having 1 to 20 carbon atoms which may contain a lactone ring, or a phenylene group or a naphthylene group. * is a bond to the carbon atom of the main chain. R 4 is an acid-labile group.

[0036] Repeating unit A2 is one in which the hydrogen atom of the phenolic hydroxy group is substituted with an acid-labile group, and in particular, one in which the hydrogen atom of the hydroxy group of hydroxystyrene or hydroxyphenyl (meth)acrylate is substituted with an acid-labile group is preferred. Preferred examples of repeating unit A2 include, but are not limited to, those shown below. In the following formulas, R A and R 3 are the same as described above.

Chemical formula

[0037] Also, repeating unit A3 is one in which the hydrogen atom of the carboxy group is substituted with an acid-labile group, and in particular, one in which the hydrogen atom of the carboxy group of (meth)acrylate is substituted with an acid-labile group is preferred. Preferred examples of repeating unit A3 include, but are not limited to, those shown below. In the following formulas, R Aand R 4 is the same as described above. [Chemical formula]

[0038] [Chemical formula]

[0039] R 3 and R 4 Examples of the acid-labile group represented by R and R include those used in many known chemically amplified resist compositions and are not particularly limited as long as they can be cleaved by an acid to give an acidic group, and any such group can be used. For example, examples of the acid-labile group include those described in paragraphs

[0030] to

[0082] of JP-A-2014-219657.

[0040] The acid-labile group is preferably represented by the following formulas (AL-1) to (AL-19). [Chemical formula] (In the formula, the dashed line represents a bond.)

[0041] In formulas (AL-1) to (AL-19), R L1 is each independently a saturated hydrocarbyl group or an aryl group having 6 to 20 carbon atoms. R L2 and R L4 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 20 carbon atoms. R L3 is an aryl group having 6 to 20 carbon atoms. The saturated hydrocarbyl group may be linear, branched or cyclic. Further, as the aryl group, a phenyl group or the like is preferable. R F is a fluorine atom or a trifluoromethyl group. n is an integer of 1 to 5. Particularly preferable structures are (AL-1), (AL-2), and (AL-19), and improvement in resolution can be obtained by suppressing swelling during alkali development.

[0042] Selecting a tertiary hydrocarbyl group as the acid-unstable group is preferable because it allows the resist film to be formed with a thickness of, for example, 10 to 100 nm, and even when forming a fine pattern with a line width of 45 nm or less, the LER (Low Line Efficiency) provides a small pattern. The tertiary hydrocarbyl group is preferably one having 4 to 18 carbon atoms in order to obtain the monomer for polymerization by distillation. Furthermore, the group bonded to the tertiary carbon atom of the tertiary hydrocarbyl group may be a saturated hydrocarbyl group having 1 to 20 carbon atoms, which may contain oxygen atom-containing functional groups such as ether bonds or carbonyl groups, and the groups bonded to the tertiary carbon atom may bond to each other to form a ring.

[0043] Specific examples of groups bonded to the tertiary carbon atom include methyl group, ethyl group, propyl group, adamantyl group, norbornyl group, tetrahydrofuran-2-yl group, 7-oxanorbornan-2-yl group, cyclopentyl group, 2-tetrahydrofuryl group, tricyclo[5.2.1.0 2,6 ] Decyl group, tetracyclo[4.4.0.1 2,5 .1 7,10 Examples include the dodecyl group and the 3-oxo-1-cyclohexyl group.

[0044] The aforementioned tertiary hydrocarbyl groups include tert-butyl group, tert-pentyl group, 1-ethyl-1-methylpropyl group, 1,1-diethylpropyl group, 1,1,2-trimethylpropyl group, 1-adamantyl-1-methylethyl group, 1-methyl-1-(2-norbornyl)ethyl group, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, 1-methyl-1-(7-oxanorbornan-2-yl)ethyl group, 1-methylcyclopentyl group, 1-ethylcyclopentyl group, 1-propylcyclopentyl group, and 1-iso Propylcyclopentyl group, 1-cyclopentylcyclopentyl group, 1-cyclohexylcyclopentyl group, 1-(2-tetrahydrofuryl)cyclopentyl group, 1-(7-oxanorbornan-2-yl)cyclopentyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group, 1-isopropylcyclohexyl group, 1-cyclopentylcyclohexyl group, 1-cyclohexylcyclohexyl group, 2-methyl-2-norbornyl group, 2-ethyl-2-norbornyl group, 8-methyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 8-ethyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 3-methyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 3-ethyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 3-isopropyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 Examples include dodecyl group, 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 2-isopropyl-2-adamantyl group, 1-methyl-3-oxo-1-cyclohexyl group, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, 5-hydroxy-2-methyl-2-adamantyl group, 5-hydroxy-2-ethyl-2-adamantyl group, and 2-(4-fluorophenyl)-2-propyl group.

[0045] Furthermore, the acetal group represented by the following formula (AL-20) is frequently used as an acid-unstable group and is a useful choice for stably providing patterns with a relatively rectangular interface between the pattern and the substrate. [ka]

[0046] In formula (AL-20), R L5 R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. L6 This is a saturated hydrocarbyl group having 1 to 30 carbon atoms.

[0047] R L5 The choice of R depends on the design of the sensitivity of the decomposition group to acid. For example, if the design requires decomposition with a strong acid while ensuring relatively high stability, a hydrogen atom is chosen, while if the design requires high sensitivity to pH changes using relatively high reactivity, a linear alkyl group is chosen. The choice of R also depends on the combination with the acid generator and basic compound incorporated into the resist composition. L6 When a relatively large alkyl group is substituted at the terminal and the change in solubility due to decomposition is designed to be significant, R L5 Preferably, the carbon bonded to the acetal carbon is a secondary carbon atom. L5 Examples of these groups include isopropyl, sec-butyl, cyclopentyl, and cyclohexyl groups.

[0048] Of the aforementioned acetal groups, R is used to obtain higher resolution. L6 It is preferable that R is a polycyclic alkyl group having 7 to 30 carbon atoms. L6 When 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 the bond is on the secondary carbon atom of the ring structure, the polymer becomes a more stable compound compared to when the bond is on the tertiary carbon atom, resulting in better storage stability as a resist composition and no deterioration in resolution.L6 Compared to cases where the polymer is bonded on primary carbon atoms with a linear alkyl group having one or more carbon atoms interposed, the glass transition temperature (Tg) of the polymer is better, and the resist pattern after development does not suffer shape defects due to baking.

[0049] Preferred examples of the group represented by formula (AL-20) are, but are not limited to, those listed below. Note that in the following formula, R L5 This is the same as described above. [ka]

[0050] The repeating unit A2 is preferably represented by the following formula (A2-1), and the repeating unit A3 is preferably represented by the following formula (A3-1). [ka] (In the formula, R A and X 3 This is the same as above. R 5 and R 6 These are, independently, acid-unstable groups having an aromatic hydrocarbon group with 6 to 20 carbon atoms and / or an alicyclic hydrocarbon group with 5 to 20 carbon atoms.

[0051] The repeating unit A3 can also be expressed by the following formula (A3-2). [ka]

[0052] In formula (A3-2), R A and X 3 This is the same as above. R B and R CEach of these is independently a C1-C10 hydrocarbyl group which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C10 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, 2-ethylhexyl, and n-octyl groups; and C3-C10 cyclic saturated hydrocarbyl groups such as cyclopentyl, cyclohexyl, norbornyl, tricyclodecanyl, and adamantyl groups.

[0053] Also, R B and R C These elements may bond to each other to form a ring with the carbon atoms to which they are bonded. Examples of such rings include cyclopropane rings, cyclobutane rings, cyclopentane rings, and cyclohexane rings. Of these, cyclopentane rings and cyclohexane rings are preferred.

[0054] In formula (A3-2), R 7 Each of these is 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. Examples of the fluorinated alkyl group include fluoromethyl group, difluoromethyl group, trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, pentafluoropropyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group, nonafluorobutyl group, etc. Examples of the fluorinated alkoxy group include fluoromethoxy group, difluoromethoxy group, trifluoromethoxy group, 2,2,2-trifluoroethoxy group, pentafluoroethoxy group, pentafluoropropoxy group, 1,1,1,3,3,3-hexafluoro-2-propoxy group, nonafluorobutoxy group, etc. Of these, R 7 Preferably, it is a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms, and more preferably a fluorine atom.

[0055] In formula (A3-2), R 8Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A specific example is R B and R C Examples of hydrocarbyl groups represented by the same formula as those exemplified above include those shown.

[0056] In formula (A3-2), n1 is 1 or 2. n2 is an integer from 0 to 5, but is preferably 0 or 1. n3 is an integer from 0 to 2. When n3 is 0, it is a benzene ring; when n3 is 1, it is a naphthalene ring; and when n3 is 2, it is an anthracene ring. However, from the viewpoint of solvent solubility, it is preferable that n3 is 0 and it is a benzene ring.

[0057] The repeating unit represented by formula (A3-2) is preferably the one represented by formula (A3-3) below. [ka] (In the formula, R A , R B , R C , X 3 , R 7 , R 8 (n1 and n2 are the same as above.)

[0058] The repeating units represented by formula (A3-2) include, but are not limited to, the following. Note that in the formula below, R A This is the same as described above. [ka]

[0059] [ka]

[0060] [ka]

[0061]

change

[0062]

change

[0063]

change

[0064]

change

[0065]

change

[0066]

change

[0067]

change

[0068]

change

[0069]

change

[0070]

change

[0071]

change

[0072]

change

[0073]

change

[0074]

change

[0075]

change

[0076]

change

[0077]

change

[0078]

change

[0079]

change

[0080]

change

[0081]

change

[0082]

change

[0083]

change

[0084]

change

[0085]

change

[0086]

change

[0087]

change

[0088]

change

[0089]

change

[0090] Acid-unstable groups protected by tertiary benzyl alcohols have a much lower activation energy for acid-catalyzed deprotection compared to acid-unstable groups of tertiary alkyl groups such as tert-butyl groups, and the deprotection reaction proceeds even at temperatures of around 50°C. When a polymer with acid-unstable groups that have too low an activation energy for deprotection is used as a base polymer, the post-exposure bake (PEB) temperature becomes too low, making it difficult to control temperature uniformity and acid diffusion. If the acid diffusion distance cannot be controlled, the dimensional uniformity and critical resolution of the pattern after development will decrease. An appropriate PEB temperature is necessary for acid diffusion control, and a range of approximately 80-100°C is suitable.

[0091] Another problem with using low-activation-energy protecting groups is that, in polymers copolymerized with photoacid generators (PAGs), the protecting group may be removed during polymerization. While onium salt PAGs are basically neutral, heating during polymerization can cause partial dissociation of the onium salt, and if repeating units with phenolic hydroxyl groups are copolymerized simultaneously, an exchange reaction between the proton of the phenolic hydroxyl group and the cation of the PAG can occur, generating acid and leading to the deprotection of the protecting group. This deprotection during polymerization is particularly pronounced when using low-activation-energy protecting groups.

[0092] As mentioned earlier, acid-unstable groups protected by tertiary benzyl alcohols have the advantage of excellent etching resistance because they contain a benzene ring, but when PAG is copolymerized, elimination occurs during polymerization. Attaching an electron-withdrawing group to the benzene ring increases the activation energy of deprotection. This is thought to be because the electron-withdrawing group reduces the stability of the benzyl cation, an intermediate in the deprotection process. By attaching an electron-withdrawing group to a protecting group that is very easy to deprotect, the reactivity of the deprotection reaction can be reduced and optimized.

[0093] Introducing a fluorine atom into the protecting group is expected to improve resolution by suppressing swelling during alkaline development. However, when a fluorine atom is introduced into the acid-unstable group of a tertiary alkyl group, the electron-withdrawing effect of the fluorine atom severely reduces the stability of the intermediate cation in the deprotection reaction, preventing the formation of olefins and thus preventing the deprotection reaction from occurring. However, a tertiary acid-unstable group having an aromatic group containing a fluorine atom exhibits optimal intermediate cation stability, shows appropriate deprotection reactivity, and also provides an improved etching resistance effect.

[0094] Based on the above, by using the polymer as the base polymer of a positive-type resist composition, particularly a chemically amplified positive-type resist composition, in order to suppress acid diffusion and improve dissolution contrast and etching resistance, the alkali dissolution rate contrast before and after exposure is significantly higher, the effect of suppressing acid diffusion is high, it has high resolution, the pattern shape and LER after exposure are good, and it exhibits even better etching resistance.

[0095] Repeating unit A2 is preferably introduced in an amount of 2 to 40 mol% of the total repeating units of the polymer contained in the base polymer, and repeating unit A3 is preferably introduced in an amount of 2 to 40 mol% of the total repeating units of the polymer contained in the base polymer. When repeating units A2 and A3 are combined, they are preferably introduced in an amount of 8 to 60 mol%, and more preferably 10 to 40 mol%, of the total repeating units of the polymer contained in the base polymer.

[0096] As part of the design of the base polymer, by mixing acid-unstable groups protected by two types of acid-unstable groups, phenolic hydroxyl groups and carboxyl groups, the dissolution rate of the exposed areas is improved by the carboxylate skeleton while maintaining pattern rigidity due to the phenol skeleton. This optimizes the dissolution contrast between the exposed and unexposed areas while maintaining good resolution in the exposed areas. As a result, the effects of development loading are suppressed, and patterns with small dimensional differences are obtained, independent of pattern density. When fabricating photomasks, the development conditions are stronger than when processing wafer substrates, so it is required to form patterns with good resolution and small dimensional differences that suppress the effects of development loading. Therefore, the chemically amplified positive resist composition of the present invention is particularly suitable for photomask substrate processing.

[0097] Preferably, the polymer contained in the base polymer further includes at least one selected from the repeating units represented by the following formula (B1) (hereinafter also referred to as repeating unit B1), the repeating unit represented by the following formula (B2) (hereinafter also referred to as repeating unit B2), and the repeating unit represented by the following formula (B3) (hereinafter also referred to as repeating unit B3). [ka]

[0098] In equations (B1) and (B2), g and h are independent integers between 0 and 4.

[0099] In formulas (B1) and (B2), R 11 and R 12 Each of these is independently a hydroxyl group, a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, and saturated hydrocarbyl carbonyloxy group may be linear, branched, or cyclic. When g is 2 or more, each R11 may be the same as or different from each other. When h is 2 or more, each R 12 may be the same as or different from each other.

[0100] In formula (B3), R A is the same as described above. i is an integer from 0 to 5. j is an integer from 0 to 2.

[0101] 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 j 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 i is 2 or more, each R 13 may be the same as or different from each other.

[0102] In formula (B3), X 4 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * is a bond to the carbon atom of the main chain.

[0103] In formula (B3), A 3 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 those similar to those exemplified in the description of A 1 in formula (A1).

[0104] When repeating units B1 to B3 are used, in addition to the etching resistance of the aromatic ring, the addition of a ring structure to the main chain enhances resistance to EB irradiation during etching and pattern inspection.

[0105] To obtain the effect of improving etching resistance, it is preferable that repeating units B1 to B3 be introduced in an amount of 5 mol% or more of the total repeating units of the polymer contained in the base polymer. Furthermore, it is preferable that repeating units B1 to B3 be introduced in an amount of 30 mol% or less of the total repeating units constituting the base polymer, and more preferably 25 mol% or less. If the amount introduced is 30 mol% or less when there is no functional group or when the functional group is not a hydroxyl group, it is preferable because there is no risk of development defects occurring. Repeating units B1 to B3 may be used individually or in combination of two or more types.

[0106] The content of at least one repeating unit selected from repeating unit A1 and repeating units B1 to B3 in the total repeating units of the polymer contained in the base polymer is preferably 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more.

[0107] In the base polymer, the repeating units having an aromatic ring skeleton are preferably 65 mol% or more, more preferably 85 mol% or more, and even more preferably all units are repeating units having an aromatic ring skeleton.

[0108] The content of at least one repeating unit selected from repeating units A1, A2, A3, and B1 to B3 in the total repeating units of the polymer contained in the base polymer is preferably 80 mol% or more, and more preferably 90 mol% or more.

[0109] The polymer included in the base polymer preferably does not contain repeating units that generate acid upon exposure. In other words, the polymer included in the base polymer preferably is not a so-called PAG bound polymer. In the design of the present invention, repeating units that generate acid upon exposure may cause swelling during alkaline development, potentially degrading resolution.

[0110] The polymer may contain commonly used (meth)acrylic acid ester units protected by acid-unstable groups, or (meth)acrylic acid ester units having adhesive groups such as lactone structures or hydroxyl groups other than phenolic hydroxyl groups. While these repeating units allow for fine-tuning of the properties of the resist film, they are not required to be included.

[0111] Examples of (meth)acrylic acid ester units having the aforementioned adhesive group include the repeating unit represented by the following formula (B4) (hereinafter also referred to as repeating unit B4), the repeating unit represented by the following formula (B5) (hereinafter also referred to as repeating unit B5), and the repeating unit represented by the following formula (B6) (hereinafter also referred to as repeating unit B6). These units do not exhibit acidity and can be used auxiliaryly as units that provide adhesion to the substrate or as units that adjust solubility. [ka]

[0112] In formulas (B4) to (B6), R A This is the same as above. R 14 R is either an -O- or a methylene group. 15 R is a hydrogen atom or a hydroxyl group. 16 k is a saturated hydrocarbyl group having 1 to 4 carbon atoms. k is an integer from 0 to 3.

[0113] When repeating units B4 to B6 are included, their content is preferably 0 to 20 mol%, and more preferably 0 to 10 mol%, of the total repeating units of the polymer contained in the base polymer. Repeating units B4 to B6 may be used individually or in combination of two or more types.

[0114] The aforementioned polymer can be synthesized by copolymerizing each monomer, which is optionally protected with a protecting group, using known methods, and then performing a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but radical polymerization and anionic polymerization are preferred. For these methods, refer to Japanese Patent Application Publication No. 2004-115630.

[0115] The polymer preferably has a weight-average molecular weight (Mw) of 1,000 to 50,000, and more preferably 2,000 to 20,000. If Mw is 1,000 or more, there is no risk of phenomena such as the pattern heads becoming rounded, reducing resolution, and LER degradation, as is conventionally known. On the other hand, if Mw is 50,000 or less, there is no risk of LER degradation, especially when forming patterns with a pattern line width of 100 nm or less. In this invention, Mw is a polystyrene-converted measurement value obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0116] The polymer preferably has a narrow dispersion with a molecular weight distribution (Mw / Mn) of 1.0 to 2.0, preferably 1.0 to 1.9, and more preferably 1.0 to 1.8. When the dispersion is narrow in this way, no foreign matter is generated on the pattern or the shape of the pattern deteriorates after development.

[0117] Furthermore, regarding the base polymer design, the dissolution rate in alkaline developer is preferably 10 nm / min or less, more preferably 7 nm / min or less, and even more preferably 5 nm / min or less. In advanced generations, when the coated film on the substrate is in the thin film region (100 nm or less), the effect of pattern film reduction on alkaline development becomes significant, and if the alkali dissolution rate of the polymer is greater than 10 nm / min, the pattern collapses, making it impossible to form fine patterns. This is particularly noticeable in the fabrication of photomasks, where defect-free conditions are required, as the development process tends to be more intense. In this invention, the dissolution rate of the base polymer in alkaline developer is calculated from the amount of film reduction when a polymer solution (polymer concentration: 16.7% by mass, solvent: propylene glycol monomethyl ether acetate (PGMEA)) is spin-coated onto 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 solution of tetramethylammonium hydroxide (TMAH) at 23°C for 100 seconds.

[0118] [Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention may contain a fluorine atom-containing polymer, which includes at least one selected from repeating units represented by the following formula (C1), repeating units represented by the following formula (C2), repeating units represented by the following formula (C3), and repeating units represented by the following formula (C4) (hereinafter also referred to as repeating units C1, C2, C3, and C4, respectively), and may further contain at least one selected from repeating units represented by the following formula (C5) and repeating units represented by the following formula (C6, respectively). The fluorine atom-containing polymer also functions as a surfactant, thus preventing the re-adhesion of insoluble substances to the substrate during the development process, and thus exhibiting an effect against development defects. [ka]

[0119] In formulas (C1) to (C6), R D These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. E Each of these is independently either a hydrogen atom or a methyl group. 101 , R 102 , R 104 and R 105 Each of these is independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 103 , R 106 , R 107 and R 108 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, or an acid-unstable group, and R 103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. 109 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. 110 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a heteroatom interposed between the carbon-carbon bonds. 111 This 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 some of the -CH2- groups constituting the saturated hydrocarbyl group may be substituted with ester bonds or ether bonds. x is an integer from 1 to 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is 0 or 1. m is an integer from 1 to 3. Z 1 This 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. 2 The bond is a single bond, *-C(=O)-O- or *-C(=O)-NH-. * represents a bond with a carbon atom in the main chain.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.

[0120] In formulas (C1) and (C2), R 101 , R 102 , R 104 and R 105 Examples of the saturated hydrocarbyl group having 1 to 10 carbon atoms represented by 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.

[0121] In formulas (C1) to (C4), R 103 , R 106 , R 107 and R 108Examples of C1-C15 hydrocarbyl groups represented by include C1-C15 alkyl groups, C2-C15 alkenyl groups, C2-C15 alkynyl groups, etc., but C1-C15 alkyl groups are preferred. Examples of the alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. Examples of the alkyl groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, n-pentyl group, n-hexyl group, n-hexyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, etc. Examples of fluorinated hydrocarbyl groups include groups in which some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbyl group mentioned above are substituted with fluorine atoms.

[0122] In formula (C4), Z 1 Examples of (m+1) valent hydrocarbon groups having 1 to 20 carbon atoms, represented by , include alkyl groups having 1 to 20 carbon atoms or cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms from which m hydrogen atoms have been removed. Also, Z 1 Examples of (m+1) valent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, as represented by the formula, include groups in which at least one hydrogen atom of the aforementioned (m+1) valent hydrocarbon group is substituted with a fluorine atom.

[0123] Specific examples of repeating units C1 to C4 are shown below, but are not limited to these. Note that in the following formula, R D This is the same as described above. [ka]

[0124] [ka]

[0125] [ka]

[0126] In formula (C5), R109 and R 110 Examples of C1-C5 hydrocarbyl groups represented by include alkyl groups, alkenyl groups, and alkynyl groups, but alkyl groups are preferred. Examples of the alkyl groups include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, sec-butyl groups, and n-pentyl groups. In addition, groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms may be interposed between the carbon-carbon bonds of these groups.

[0127] In formula (C5), -OR 109 It is preferable that R is a hydrophilic group. In this case, R 109 Preferred elements include hydrogen atoms, C1-C5 alkyl groups with oxygen atoms interposed between carbon-carbon bonds, etc.

[0128] In formula (C5), Z 2 It is preferable that *-C(=O)-O- or *-C(=O)-NH-. Furthermore, R E It is preferable that it is a methyl group. 2 The presence of a carbonyl group improves the acid trapping ability derived from the antistatic film. Also, R E When the group is a methyl group, a more rigid polymer with a higher glass transition temperature (Tg) is formed, thus suppressing acid diffusion. This results in good temporal stability of the resist film, and the resolution and pattern shape do not deteriorate.

[0129] The repeating unit C5 can be, but is not limited to, the following. Note that in the following formula, R E This is the same as described above. [ka]

[0130] [ka]

[0131] In formula (C6), Z 3The saturated hydrocarbylene group having 1 to 10 carbon atoms, represented by , may be linear, branched, or cyclic. Specific examples include methanediyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-1,1-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-2,3-diyl group, butane-1,4-diyl group, and 1,1-dimethylethane-1,2-diyl group.

[0132] In formula (C6), R 111 A saturated hydrocarbyl group having 1 to 20 carbon atoms, represented by , in which at least one hydrogen atom is substituted with a fluorine atom, may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 20 carbon atoms or cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom.

[0133] The repeating unit C6 can be, but is not limited to, the following. Note that in the following formula, R E This is the same as described above. [ka]

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] The content of repeating units C1 to C4 is preferably 15 to 95 mol%, and more preferably 20 to 85 mol%, of the total repeating units of the fluorine atom-containing polymer. The content of repeating units C5 and / or C6 is preferably 5 to 85 mol%, and more preferably 15 to 80 mol%, of the total repeating units of the fluorine atom-containing polymer. Repeating units C1 to C6 may be used individually or in combination of two or more types.

[0138] The fluorine atom-containing polymer may contain other repeating units besides those described above. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of Japanese Patent Application Publication No. 2014-177407. If the fluorine atom-containing polymer contains other repeating units, the content thereof is preferably 50 mol% or less of the total repeating units of the fluorine atom-containing polymer.

[0139] The aforementioned fluorine atom-containing polymer can be synthesized by copolymerizing each monomer, which is optionally protected with a protecting group, using known methods, and then performing a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but radical polymerization and anionic polymerization are preferred. For these methods, refer to Japanese Patent Application Publication No. 2004-115630.

[0140] The Mw of the fluorine atom-containing polymer is preferably 2,000 to 50,000, and more preferably 3,000 to 20,000. If the Mw is less than 2,000, it may promote acid diffusion, leading to a deterioration in resolution and impaired stability over time. If the Mw is too high, the solubility in the solvent will decrease, potentially causing coating defects. Furthermore, the Mw / Mn of the fluorine atom-containing polymer is preferably 1.0 to 2.2, and more preferably 1.0 to 1.7.

[0141] When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer, its content is preferably 0.01 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.5 to 10 parts by mass, based on 80 parts by mass of the base polymer.

[0142] [Organic solvents] 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, as described in paragraphs

[0144] to

[0145] of Japanese Patent Application Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and ethylene glycol Examples include ethers such as monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, propylene glycol monoethyl ether acetate, 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 using acetal-based acid-unstable groups, high-boiling point alcohol-based solvents, specifically diethylene glycol, propylene glycol, glycerin, 1,4-butanediol, and 1,3-butanediol, can be added to accelerate the deprotection reaction of the acetal.

[0143] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixtures thereof are preferred.

[0144] When the chemically amplified positive resist composition of the present invention contains the organic solvent, its content is preferably 200 to 10,000 parts by mass, and more preferably 400 to 5,000 parts by mass, per 80 parts by mass of the base polymer. The organic solvent may be used alone or as a mixture of two or more.

[0145] [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 acid upon irradiation with high-energy rays. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxiimide, oxime-O-sulfonate type acid generators, and the like.

[0146] Specific examples of the photoacid generator include nonafluorobutanesulfonate, partially fluorinated sulfonates described in paragraphs

[0247] to

[0251] of Japanese Patent Publication No. 2012-189977, partially fluorinated sulfonates described in paragraphs

[0261] to

[0265] of Japanese Patent Publication No. 2013-101271, and those described in paragraphs

[0122] to

[0142] of Japanese Patent Publication No. 2008-111103 and paragraphs

[0080] to

[0081] of Japanese Patent Publication No. 2010-215608. Among these specific examples, arylsulfonate type or alkanesulfonate type photoacid generators are preferred because they generate an acid of appropriate strength for deprotecting the acid-unstable group of the repeating unit represented by formula (A2) or (A3).

[0147] As such a photoacid generator, compounds having an anion with the structure shown below are preferred. [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] As the cation paired with the anion, a sulfonium cation represented by the following formula (D) or an iodonium cation represented by the following formula (E) is preferred. [ka]

[0155] In equations (D) and (E), R 201 ~R 205 Each of these is independently a C1-C20 hydrocarbyl group which may contain a halogen atom or a heteroatom.

[0156] Examples of the halogen atoms mentioned above include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0157] The aforementioned hydrocarbyl group having 1 to 20 carbon atoms may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; C3-C20 cyclic saturated hydrocarbyl groups such as cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, tricyclo[5.2.1.02,6]decanyl, adamantyl, and adamantylmethyl groups; and C6-C20 aryl groups such as phenyl, naphthyl, and anthracenyl groups. Furthermore, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with groups containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and groups containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms may be interposed between the carbon-carbon bonds of the hydrocarbyl group, and as a result, it may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0158] Also, R 201 and R 202 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded. Examples of rings formed in this case include those shown below. [ka] (In the formula, the dashed line represents R 203 (This is a combination of the two.)

[0159] Specific examples of sulfonium cations represented by formula (D) are listed below, but are not limited to these.

change

[0160]

change

[0161]

change

[0162]

change

[0163]

change

[0164]

change

[0165]

change

[0166]

change

[0167]

change

[0168]

change

[0169]

change

[0170]

change

[0171]

change

[0172]

change

[0173]

change

[0174]

change

[0175]

change

[0176]

change

[0177]

change

[0178]

change

[0179]

change

[0180]

change

[0181] Specific examples of iodonium cations represented by formula (E) are listed below, but are not limited to these. [ka]

[0182] [ka]

[0183] The acid generated by the aforementioned photoacid generator preferably has a pKa of -2.0 or higher. Furthermore, the upper limit of the pKa is preferably 2.0. The pKa values ​​were calculated using the pKa DB in the ACD / Chemsketch ver:9.04 software from Advanced Chemistry Development, Inc.

[0184] If the chemically amplified positive resist composition of the present invention contains a photoacid generator, its content is preferably 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass, per 80 parts by mass of the base polymer. The photoacid generator may be used alone or in combination of two or more types.

[0185] [Quencher] The chemically amplified positive resist composition of the present invention preferably contains a quencher. Examples of the quencher include conventional basic compounds. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxyl group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxyl 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 Japanese Patent Publication No. 2008-111103 are preferred, especially amine compounds having a hydroxyl group, ether bond, ester bond, lactone ring, cyano group, or sulfonic acid ester bond, or compounds having a carbamate group described in Japanese Patent No. 3790649. Preferred examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine N-oxide, dibutylaminobenzoic acid, morpholine derivatives, and imidazole derivatives. By adding such basic compounds, it is possible to further suppress the diffusion rate of the acid in the resist film or correct its shape, for example.

[0186] Furthermore, 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 Japanese Patent Publication No. 2008-158339. Sulfonic acids, imido acids, or methidic acids with α-position fluorinated are necessary for deprotecting acid-unstable groups, but salt exchange with onium salts whose α-position is not fluorinated releases carboxylic acids whose α-position is not fluorinated. Carboxylic acids whose α-position is not fluorinated hardly undergo deprotection reactions and therefore function as quenchers.

[0187] Examples of onium salts of carboxylic acids whose α-position is not fluorinated include those represented by the following formula (F1). [ka]

[0188] In formula (F1), R 301 This refers to a hydrocarbyl group having 1 to 40 carbon atoms, which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the α-carbon atom of the sulfo group is substituted with a fluorine atom or a fluoroalkyl group.

[0189] The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include alkyl groups having 1 to 40 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, tert-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups; cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, and tricyclo[5.2.1.0 2,6 ] Cyclic saturated hydrocarbyl groups with 3 to 40 carbon atoms, such as decanyl group, adamantyl group, and adamantylmethyl group; alkenyl groups with 2 to 40 carbon atoms, such as vinyl group, allyl group, propenyl group, butenyl group, and hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups with 3 to 40 carbon atoms, such as cyclohexenyl group; phenyl group, naphthyl group, alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-methylmethylphenyl group, 4-methylphenyl group, methylphenyl group, methylphenyl group, 4-methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, methylphenyl group, Examples include aryl groups with 6 to 40 carbon atoms, such as t-butylphenyl group, 4-n-butylphenyl group, dialkylphenyl group (2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group, etc.), alkylnaphthyl group (methylnaphthyl group, ethylnaphthyl group, etc.), and dialkylnaphthyl group (dimethylnaphthyl group, diethylnaphthyl group, etc.); and aralkyl groups with 7 to 40 carbon atoms, such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0190] Furthermore, some of the hydrogen atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of the carbon atoms of these groups may be substituted with heteroatom-containing groups such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, they may contain hydroxyl groups, cyano groups, carbonyl groups, ether bonds, thioether bonds, ester bonds, sulfonic acid ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic acid anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc. Examples of hydrocarbyl groups containing heteroatoms include heteroaryl groups such as thienyl groups; alkoxyphenyl groups such as 4-hydroxyphenyl, 4-methoxyphenyl, 3-methoxyphenyl, 2-methoxyphenyl, 4-ethoxyphenyl, 4-tert-butoxyphenyl, and 3-tert-butoxyphenyl groups; alkoxynaphthyl groups such as methoxynaphthyl, ethoxynaphthyl, n-propoxynaphthyl, and n-butoxynaphthyl groups; dialkoxynaphthyl groups such as dimethoxynaphthyl and diethoxynaphthyl groups; and aryloxoalkyl groups such as 2-aryl-2-oxoethyl groups such as 2-phenyl-2-oxoethyl, 2-(1-naphthyl)-2-oxoethyl, and 2-(2-naphthyl)-2-oxoethyl groups.

[0191] In formula (F1), Mq + This is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation, or an ammonium cation, and more preferably a sulfonium cation or an iodonium cation. The sulfonium cation is the same as the one exemplified as the sulfonium cation represented by formula (D). The iodonium cation is the same as the one exemplified as the iodonium cation represented by formula (E).

[0192] The anions of the salt represented by formula (F1) include, but are not limited to, those listed below. [ka]

[0193] [ka]

[0194] [ka]

[0195] As the quencher, a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (F2) can also be suitably used. [ka]

[0196] In formula (F2), R 401 This may be 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, or -N(R 401A )-C(=O)-R 401B Or -N(R 401A )-C(=O)-OR 401B That is. R 401A R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 401B This is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0197] In equation (F2), p is an integer between 1 and 5. q is an integer between 0 and 3. r is an integer between 1 and 3. L 1This is a single bond or a (r+1) valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, carbonyl group, ester bond, amide bond, sultone ring, lactam ring, carbonate bond, halogen atom, hydroxyl group, and carboxyl group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When q and / or r is 2 or more, each R 401 They may be the same or different from one another.

[0198] In formula (F2), R 402 , R 403 and R 404 Each of these is a C1-C20 hydrocarbyl group, which may independently contain a halogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples include C1-C20 alkyl groups, C2-C20 alkenyl groups, C6-C20 aryl groups, C7-C20 aralkyl groups, etc. Furthermore, some or all of the hydrogen atoms of these groups may be substituted with a hydroxyl group, carboxyl group, halogen atom, oxo group, cyano group, nitro group, sultone group, sulfone group, or sulfonium salt-containing group, and some of the carbon atoms of these groups may be substituted with an ether bond, ester bond, carbonyl group, amide bond, carbonate bond, or sulfonic acid ester bond. 402 and R 403 However, they may bond with each other to form a ring with the sulfur atom to which they are bonded.

[0199] A specific example of the compound represented by formula (F2) is the one described in Japanese Patent Publication No. 2017-219836. The compound represented by formula (F2) exhibits high absorption, high sensitization effect, and high acid diffusion control effect.

[0200] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (F3) can also be used. [ka]

[0201] In formula (F3), R 501 ~R 504 These are, independently, hydrogen atoms and -L 2 -CO2 - or a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. 501 and R 502 And, R 502 and R 503 or R 503 and R 504 These may bond with each other to form a ring with the carbon atom to which they are bonded. 2 R is a hydroxylene group having 1 to 20 carbon atoms, which may contain single bonds or heteroatoms. 505 This is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom.

[0202] In formula (F3), ring R is a ring having 2 to 6 carbon atoms, including the carbon and nitrogen atoms in the formula, and some 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 2 -CO2 - The ring may be substituted with a sulfur atom, oxygen atom, or nitrogen atom. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5-membered or 6-membered ring. Specific examples include pyridine rings, pyrrole rings, pyrrolidine rings, piperidine rings, pyrazole rings, imidazoline rings, pyridazine rings, pyrimidine rings, pyrazine rings, imidazoline rings, oxazole rings, thiazole rings, morpholine rings, thiazine rings, triazole rings, and the like.

[0203] The onium carboxylate salt represented by formula (F3) contains at least one -L 2 -CO2 - It has a group. That is, R 501 ~R 504 At least one of them is -L 2 -CO2 -is and / or at least one hydrogen atom bonded to a carbon atom of ring R is -L 2 -CO2 - It has been replaced with this.

[0204] In formula (F3), Q + This is a sulfonium cation, an iodonium cation, or an ammonium cation, but a sulfonium cation is preferred. Examples of the sulfonium cation include those exemplified as the sulfonium cation represented by formula (D).

[0205] The anions of the compound represented by formula (F3) include, but are not limited to, those listed below. [ka]

[0206] [ka]

[0207] [ka]

[0208] [ka]

[0209] [ka]

[0210] [ka]

[0211] Furthermore, a weak acidic betaine-type compound can also be used as the quencher. Specific examples are listed below, but are not limited to these. [ka]

[0212] As an example of the aforementioned quencher, a polymer-type quencher described in Japanese Patent Publication No. 2008-239918 can be cited. This enhances the rectangularity of the resist pattern by oriented on the surface of the resist film. The polymer-type quencher also has the effect of preventing film thinning of the pattern and rounding of the pattern top when a protective film for immersion lithography is applied.

[0213] When the chemically amplified positive resist composition of the present invention contains a quencher, its content is preferably 0 to 50 parts by mass, and more preferably 0.1 to 40 parts by mass, per 80 parts by mass of the base polymer. The quencher may be used alone or in combination of two or more types.

[0214] [Surfactants] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant to improve its applicability to the substrate. When using a surfactant, many are known, as numerous examples are described in Japanese Patent Application Publication No. 2004-115630, and can be selected by referring to these. The amount of the surfactant is preferably 0 to 5 parts by mass per 80 parts by mass of the base polymer. If the fluorine atom-containing polymer is included in the chemically amplified positive resist composition of the present invention, the fluorine atom-containing polymer also acts as a surfactant, so the surfactant may not be included.

[0215] In designing the chemically amplified positive-type resist composition of the present invention, the dissolution rate of the overexposed portion of the resulting resist film in the alkaline developer is preferably 50 nm / sec or higher, more preferably 100 nm / sec or higher, and even more preferably 200 nm / sec or higher, from the viewpoint of improving development loading. A dissolution rate of 50 nm / sec or higher allows for uniform dissolution in the alkaline developer even if there are differences in pattern layout in the dense / sparse pattern, thereby reducing linewidth fluctuations. The dissolution rate of the overexposed portion in the present invention is calculated from the film loss when the chemically amplified positive-type resist composition of the present invention is spin-coated onto an 8-inch silicon wafer, baked at 110°C for 60 seconds to form a resist film with a thickness of 90 nm, exposed with KrF excimer laser light at an energy level sufficient to complete the polymer deprotection reaction, baked at 110°C for 60 seconds, and then developed at 23°C with a 2.38 mass% TMAH aqueous solution using a resist development analyzer.

[0216] Furthermore, 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 8 nm / min or less, and even more preferably 6 nm / min or less. When the resist film is in the thin film region (100 nm or less), the effect of pattern film reduction on the alkaline developer becomes large, and if the dissolution rate of the unexposed portion is greater than 10 nm / min, the pattern collapses, making it impossible to form a fine pattern. This is particularly noticeable in the fabrication of photomasks, where defect-free conditions are required, as the development process tends to be strong. The dissolution rate of the unexposed portion was calculated from the amount of film reduction when the chemically amplified positive resist composition of the present invention was spin-coated onto a 6-inch silicon wafer, baked at 110°C for 240 seconds to form a resist film with a thickness of 80 nm, and then developed in a 2.38 mass% TMAH aqueous solution at 23°C for 80 seconds.

[0217] [Method for forming a resist pattern] The resist pattern formation method of the present invention includes the steps of forming a resist film on a substrate using the chemically amplified positive-type resist composition described above, irradiating the resist film with a pattern using high-energy rays (i.e., exposing the resist film with high-energy rays), and developing the resist film irradiated with the pattern using an alkaline developer.

[0218] As the substrate, for example, substrates for integrated circuit manufacturing (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflective coatings, etc.) or substrates for 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 to the substrate by a method such as spin coating to a film thickness of 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.

[0219] Next, the resist film is exposed using high-energy rays to irradiate a pattern. Examples of high-energy rays include ultraviolet light, far-ultraviolet light, excimer laser light (KrF, ArF, etc.), EUV, X-rays, gamma rays, synchrotron radiation, and EB. In the present invention, exposure using EUV or EB is preferred.

[0220] When using ultraviolet light, far ultraviolet light, excimer laser light, EUV, X-rays, gamma rays, or synchrotron radiation as the high-energy rays, a mask is used to form the desired pattern, and the exposure amount is preferably 1 to 500 mJ / cm². 2 More preferably 10 to 400 mJ / cm² 2 Irradiate in such a manner. When using an EB, direct exposure is preferred to form the desired pattern, with an exposure dose of 1 to 500 μC / cm². 2 More preferably 10-400 μC / cm² 2 Irradiate in such a way that it results in the following.

[0221] In addition to conventional exposure methods, immersion methods, which involve immersing the mask and resist in liquid, can also be used in some cases. In such cases, a water-insoluble protective film can be used.

[0222] Next, the food is subjected to PEB (Periodic Emission Breaking) on ​​a hot plate, preferably at 60-150°C for 1-20 minutes, more preferably at 80-140°C for 1-10 minutes.

[0223] Subsequently, the substrate is developed using a developer solution of an alkaline aqueous solution such as TMAH in a concentration of 0.1 to 5% by mass, preferably 2 to 3% by mass, by conventional methods such as dipping, puddling, or spraying, preferably for 0.1 to 3 minutes, more preferably for 0.5 to 2 minutes, thereby forming the desired pattern on the substrate.

[0224] Furthermore, the chemically amplified positive resist composition of the present invention is particularly useful because it can form patterns with good resolution and low LER. In addition, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on substrates having a surface material that is prone to pattern peeling or pattern collapse because it is difficult to achieve good adhesion of the resist pattern. Suitable substrates for this purpose include substrates in which a chromium compound containing one or more light elements selected from metallic chromium, oxygen, nitrogen, and carbon is sputtered onto the outermost surface, SiO, SiO x Examples include substrates containing tantalum compounds, molybdenum compounds, cobalt compounds, nickel compounds, tungsten compounds, and tin compounds in their outermost layer. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using photomask blanks as substrates. In this case, the photomask blanks may be transmissive or reflective.

[0225] According to the resist pattern formation method of the present invention, even when a substrate (e.g., a photomask blank) is used in which the outermost surface is made of a material that easily affects the resist pattern shape, such as a material containing chromium, silicon, or tantalum, a high-resolution pattern with small dimensional differences that are independent of pattern density and suppress the effects of development loading can be obtained. [Examples]

[0226] The present invention will be specifically described below with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples. The copolymerization composition ratio is expressed as a molar ratio, and Mw is the weight-average molecular weight on a polystyrene basis as measured by GPC.

[0227] [1] Polymer synthesis [Synthesis Example 1-1] Synthesis of Polymer P-1 Under a nitrogen atmosphere, 49.3 g of 4-acetoxystyrene, 18.9 g of 4-(1-methyl-1-cyclopentyloxy)styrene, 11.8 g of 1-methylcyclopentyl methacrylate, 8.6 g of dimethyl-2,2'-azobis-(2-methylpropionate) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name V601), and 124 g of methyl ethyl ketone as a solvent were added to a 300 mL dropping cylinder to prepare a solution. Furthermore, 62 g of methyl ethyl ketone was added to another 500 mL polymerization flask under a nitrogen atmosphere, and the solution was added dropwise over 4 hours while heated to 80°C. After the addition was complete, stirring was continued for 18 hours while maintaining the polymerization temperature at 80°C, and then the mixture was cooled to room temperature. The obtained polymerization solution was added dropwise to 1,300 g of hexane, and the precipitated copolymer was filtered off. The filtered copolymer was washed twice with 500 g of hexane. The obtained copolymer was dissolved in a 1 L flask in a mixed solvent of 144 g of tetrahydrofuran and 48 g of methanol under a nitrogen atmosphere, and 22.3 g of ethanolamine was added. The mixture was stirred at 60°C for 3 hours. This reaction solution was concentrated under reduced pressure, and the resulting concentrate was dissolved in a mixed solvent of 240 g of ethyl acetate and 60 g of water. The resulting solution was transferred to a separatory funnel, 11.1 g of acetic acid was added, and the separation was performed. The lower layer was removed by distillation, and 60 g of water and 14.8 g of pyridine were added to the resulting organic layer, and the separation was performed by washing with water (a total of 5 washes). After concentration of the organic layer following liquid-liquid separation, it was dissolved in 130 g of acetone. The resulting acetone solution was added dropwise to 1,200 g of water, and the resulting precipitate was filtered, washed with water, and subjected to suction filtration for 2 hours. The resulting precipitate was again dissolved in 130 g of acetone, and the resulting acetone solution was added dropwise to 1,200 g of water. The resulting precipitate was filtered, washed with water, and dried to obtain 50.3 g of the target polymer P-1, which is a white polymer. 13 C-NMR, 1 The following analysis results were obtained by measuring using H-NMR and GPC. [ka]

[0228] [Synthesis Examples 1-2 to 1-44, Comparative Synthesis Examples 1-1, 1-2] Synthesis of polymers P-2 to P-44, comparative polymers cP-1 and cP-2 Polymers P-2 to P-44 and comparative polymers cP-1 and cP-2, shown in Tables 1 to 3 below, were synthesized using the same method as in Synthesis Example 1-1, except for changes in the type and mixing ratio of each monomer. In Tables 1 to 3 below, the introduction ratio is shown as the molar ratio.

[0229] [Table 1]

[0230] [Table 2]

[0231] [Table 3]

[0232] The structure of the repeating unit introduced into the polymer is shown below. [ka]

[0233] [ka]

[0234] [ka]

[0235] [ka]

[0236] [ka]

[0237] The dissolution rate of the polymers in the alkaline developer was calculated by spin-coating an 8-inch silicon wafer with the polymer solution (polymer concentration: 16.7% by mass, solvent: PGME), baking it at 100°C for 90 seconds to form a film with a thickness of 1,000 nm, and then developing it in a 2.38% by mass TMAH aqueous solution at 23°C for 100 seconds, measuring the amount of film loss. As a result, the dissolution rates of polymers P-1 to P-44 and comparative polymer cP-2 were 10 nm / min or less, and the dissolution rate of comparative polymer cP-1 was 20 nm / min.

[0238] [Synthesis Examples 2-1 to 2-6, Comparative Synthesis Example 1-3] Synthesis of polymers AP-1 to AP-6 and polymer cP-3 Polymers AP-1 to AP-6 and comparative polymer cP-3 were synthesized using the same method as in Synthesis Example 1-1, except that the raw material compounds used were changed. [ka]

[0239] [ka]

[0240] [ka]

[0241] The dissolution rates of polymers AP-1 to AP-6 and comparative polymer cP-3 were 10 nm / min or less.

[0242] [2] Preparation of chemically amplified positive resist compositions [Examples 1-1 to 1-58, Comparative Examples 1-1 to 1-5] Chemically amplified positive resist compositions were prepared by dissolving each component in an organic solvent with the compositions shown in Tables 4 to 7 below, and filtering the resulting solution through a 0.02 μm UPE filter. The organic solvent was a mixed solvent consisting of 340 parts by mass of PGMEA, 1,700 parts by mass of EL, and 1,360 parts by mass of PGME.

[0243] [Table 4]

[0244] [Table 5]

[0245] [Table 6]

[0246] [Table 7]

[0247] The structures of Quenchers Q-1 to Q-3, Photoacid Generators PAG-A to PAG-C, and Polymers D-1 to D-5 in Tables 4 to 7 are as follows. [ka]

[0248] [ka]

[0249] [ka]

[0250] [3] EB lithography evaluation [Examples 2-1 to 2-57, Comparative Examples 2-1 to 2-4] Each chemically amplified positive resist composition (R-1 to R-57, CR-1 to CR-4) was spin-coated onto a 152 mm square photomask blank with a chromium outer surface using ACT-M (manufactured by Tokyo Electron Ltd.). The blanks were then pre-baked on a hot plate at 110°C for 600 seconds to produce a resist film with a thickness of 80 nm. The thickness of the obtained resist films was measured using an optical measuring instrument, NanoSpec (manufactured by Nanometrics). Measurements were taken at 81 locations within the plane of the blank substrate, excluding the outer edge portion up to 10 mm inward from the outer edge, and the average thickness and thickness range were calculated.

[0251] Furthermore, exposure was performed using an electron beam lithography system (EBM-5000plus, manufactured by Newflare Technology Co., Ltd., accelerating voltage 50kV), followed by PEB at 110°C for 600 seconds, and development with a 2.38 mass% TMAH aqueous solution to obtain a positive-type pattern.

[0252] The obtained resist patterns were evaluated as follows: The fabricated patterned mask blanks were observed using an overhead SEM (scanning electron microscope), and the optimal exposure (μC / cm²) was determined to resolve 200 nm 1:1 line and space (LS) lines at a 1:1 ratio. 2 The resolution (limiting resolution) was defined as the minimum dimension at the exposure dose that resolves a 200nm LS at a 1:1 ratio, and the LER of a 200nm LS was measured by SEM. For development loading evaluation, the exposure dose (μC / cm²) that resolves a 200nm LS at a 1:1 ratio within the substrate surface was defined. 2 The dimensions of the space between a 200nm LS pattern formed using ( ) and a 200nm LS pattern with dummy patterns of densities of 15%, 25%, 33%, 45%, 50%, 55%, 66%, 75%, 85%, and 95% placed around the pattern were measured by SEM, and the difference in dimensional differences between the dense and sparse patterns was compared. The pattern shape was determined visually to determine whether it was rectangular or not.

[0253] The overexposure dissolution rate is determined by spin-coating a resist solution onto an 8-inch silicon wafer, baking it at 110°C for 60 seconds to form a 90 nm thick resist film, and then applying an exposure dose (mJ / cm²) that resolves a 200 nm 1:1 line-and-space (LS) pattern at a 1:1 ratio. 2 The resist was exposed to KrF excimer laser light, baked at 110°C for 60 seconds, and then developed at 23°C with a 2.38 mass% TMAH aqueous solution using a resist development analyzer (RDA-800, manufactured by Lithotec Japan Co., Ltd.) for calculation. The results are shown in Tables 8-10.

[0254] [Table 8]

[0255] [Table 9]

[0256] [Table 10]

[0257] [4] Etching resistance evaluation [Examples 3-1 to 3-3, Comparative Example 3-1] Each chemically amplified positive resist composition (R-9, R-22, R-58, CR-5) was spin-coated onto a 152 mm square photomask blank with a chromium outer surface using ACT-M (manufactured by Tokyo Electron Ltd.). The blanks were then pre-baked on a hot plate at 110°C for 600 seconds to produce a resist film with a thickness of 120 nm. The thickness of the obtained resist film was measured using an optical measuring instrument, NanoSpec (manufactured by Nanometrics). Measurements were taken at 81 locations within the plane of the blank substrate, excluding the outer edge portion up to 10 mm inward from the outer edge, and the average thickness and thickness range were calculated. The obtained coated substrates were dry-etched using a dry etching apparatus (UNAXIS G4) under the following conditions, and the film loss rate (A / sec) derived from the remaining film after etching was calculated. The results are shown in Table 11.

[0258] RF1(RIE): Pulse 700V RF2(ICP): CW 400W Pressure: 6 mTorr Cl2: 185sccm O2: 55 sccm He: 9.25 sccm Etching time: 75 sec

[0259] [Table 11]

[0260] The chemically amplified positive resist compositions (R-1 to R-57) of the present invention all exhibited good resolution, LER, and pattern rectangularity, and showed suppressed development loading. On the other hand, the comparative resist compositions (CR-1 to CR-4) showed different results. In CR-1, the dissolution rate of the unexposed areas of the polymer was high, resulting in a rounded shape and degraded resolution. In CR-2, the dissolution rate of the overexposed areas was too low, resulting in insufficient suppression of development loading. In CR-3 and CR-4, the base polymer design was insufficient; although development loading was good, resolution, LER, and pattern rectangularity could not be achieved simultaneously. This is thought to be because the base polymer design of the present invention, specifically by not having a PAG bound polymer backbone and combining phenolic acid-unstable groups with acrylate-based acid-unstable groups, succeeded in optimizing the pattern shape with phenolic units and the dissolution rate of the exposed areas with acrylate-based groups, thereby achieving resolution, LER, pattern rectangularity, and suppressed development loading. Furthermore, dry etching evaluations using R-9, R-22, and R-58 showed better etching resistance compared to CR-5, suggesting that having 65 mol% or more of aromatic ring skeletons in the base polymer is effective in mask processing.

[0261] The resist pattern formation method using the chemically amplified positive resist composition of the present invention is useful for semiconductor device manufacturing, particularly for photolithography in the processing of transmissive and reflective photomask blanks.

Claims

1. A chemically amplified positive-type resist composition comprising a base polymer protected by an acid-unstable group and becoming alkali-soluble upon the action of an acid, The base polymer comprises a polymer containing a phenolic hydroxyl group-containing unit, a unit in which the phenolic hydroxyl group is protected by an acid-unstable group, and a unit in which the carboxyl group is protected by an acid-unstable group, or a polymer containing a phenolic hydroxyl group-containing unit and a unit in which the phenolic hydroxyl group is protected by an acid-unstable group, and a polymer containing a phenolic hydroxyl group-containing unit and a unit in which the carboxyl group is protected by an acid-unstable group. The phenolic hydroxyl group-containing unit is a repeating unit represented by the following formula (A1), the unit in which the phenolic hydroxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A2), and the unit in which the carboxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A3), Of the total repeating units of the polymer contained in the base polymer, 65 mol% or more have an aromatic ring skeleton. A chemically amplified positive-type resist composition wherein the dissolution rate of the overexposed portion of the resist film obtained from the chemically amplified positive-type resist composition is 50 nm / sec or higher. 【Chemistry 1】 (In the equation, a is an integer satisfying 0 ≤ a ≤ 5 + 2c - b. b is an integer from 1 to 3. c is an integer from 0 to 2.) R A These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. X 1 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) is a bond to a carbon atom in the main chain. A 1 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group is composed of -CH 2 Some of the hyphens may be replaced with -O-. R 1 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. 【Chemistry 2】 (In the formula, R A The same applies as above. d is an integer satisfying 0 ≤ d ≤ 5 + 2f - e. e is an integer between 1 and 3. f is an integer between 0 and 2. X 2 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) 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 -CH 2 - constituting the saturated hydrocarbylene group may be substituted with -O-. R 2 This is a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 6 carbon atoms that may be substituted with a halogen atom. R 3 (When e is 1, it is an acid-unstable group; when e is 2 or more, it is a hydrogen atom or an acid-unstable group, but at least one is an acid-unstable group.) 【Transformation 3】 (In the formula, R A The same applies as above. X 3 This refers to a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-X 3A - and X 3A This is a saturated hydrocarbylene group having 1 to 20 carbon atoms, which may contain a hydroxyl group, an ether bond, an ester bond, or a lactone ring, or a phenylene group or a naphthylene group. * indicates a bond with a carbon atom of the main chain. R 4 It is an acid-unstable group.

2. The chemically amplified positive resist composition according to claim 1, wherein the phenolic hydroxyl group-containing unit is a repeating unit represented by the following formula (A1-1). 【Chemistry 4】 (In the formula, R A (and b are the same as above.)

3. The chemically amplified positive resist composition according to claim 1, wherein the unit in which the phenolic hydroxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A2-1). 【Transformation 5】 (In the formula, R A This is the same as above. R 5 This is an acid-unstable group having an aromatic hydrocarbon group with 6 to 20 carbon atoms and / or an alicyclic hydrocarbon group with 5 to 20 carbon atoms.

4. The chemically amplified positive resist composition according to claim 1, wherein the unit in which the carboxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A3-1). 【Transformation 6】 (In the formula, R A and X 3 This is the same as above. R 6 This is an acid-unstable group having an aromatic hydrocarbon group with 6 to 20 carbon atoms and / or an alicyclic hydrocarbon group with 5 to 20 carbon atoms.

5. The chemically amplified positive resist composition according to claim 1, wherein the unit in which the carboxyl group is protected by an acid-unstable group is a repeating unit represented by the following formula (A3-2). 【Transformation 7】 (In the formula, R A and X 3 The same applies as above. R B and R C Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms, and R B and R C These elements may bond with each other to form a ring with the carbon atoms to which they are bonded. R 7 Each of these is 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 8 Each of these is independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms. n1 is either 1 or 2. n2 is an integer between 0 and 5. n3 is an integer between 0 and 2.

6. The chemically amplified positive resist composition according to claim 5, wherein the repeating unit represented by formula (A3-2) is represented by the following formula (A3-3). 【Transformation 8】 (In the formula, R A , R B , R C , X 3 , R 7 , R 8 (n1 and n2 are the same as above.)

7. R 7 The chemically amplified positive resist composition according to claim 5, wherein the resist is a fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group.

8. The chemically amplified positive resist composition according to claim 1, wherein the polymer contained in the base polymer further includes repeating units represented by any of the following formulas (B1) to (B3). 【Chemistry 9】 (In the formula, R A The same applies as above. g and h are independent integers between 0 and 4. i is an integer between 0 and 5. j is an integer between 0 and 2. R 11 and R 12 These are, independently, a hydroxyl group, a halogen atom, a saturated hydrocarbyl carbonyloxy group having 2 to 8 carbon atoms that may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms that may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms that may be substituted with a halogen atom. R 13 This group 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. If j is 1 or 2, it may also be a hydroxyl group. X 4 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) is a bond to a carbon atom in the main chain. A 3 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the saturated hydrocarbylene group is composed of -CH 2 (Some of the hyphens may be replaced with -O-.)

9. The chemically amplified positive resist composition according to claim 8, wherein the total of the repeating units represented by formula (A1) and any of the repeating units represented by formulas (B1) to (B3) is 50 mol% or more of the total repeating units of the polymer contained in the base polymer.

10. The chemically amplified positive resist composition according to claim 1, further comprising a fluorine atom-containing polymer that includes at least one selected from the repeating units represented by the following formula (C1), the repeating units represented by the following formula (C2), the repeating units represented by the following formula (C3), and the repeating units represented by the following formula (C4), and which may further include at least one selected from the repeating units represented by the following formula (C5) and the repeating units represented by the following formula (C6). 【Chemistry 10】 (In the formula, R D These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R E Each of these is independently either a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 Each of these is independently either a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 Each of these is independently a hydrogen atom, a C1-C15 hydrocarbyl group, a C1-C15 fluorinated hydrocarbyl group, or an acid-unstable group, R 103 , R 106 , R 107 and R 108 When the group is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be interposed between the carbon-carbon bonds. R 109 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a hydrogen atom or a group containing a heteroatom between the carbon-carbon bonds. R 110 This is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms, which may have a heteroatom interposed between the carbon-carbon bonds. R 111 This is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom, and the saturated hydrocarbyl group is composed of -CH 2 A portion of the - may be substituted with an ester bond or an ether bond. x is an integer between 1 and 3. y is an integer satisfying 0 ≤ y ≤ 5 + 2z - x. z is either 0 or 1. m is an integer between 1 and 3. Z 1 This 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. Z 2 The bond is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. The asterisk (*) is a bond to a carbon atom in the main chain. Z 3 This is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or * - C (= O) - NH - Z 31 -Z 32 - is Z 31 This is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 A is a single bond, ester bond, ether bond, or sulfonamide bond. * indicates a bond to a carbon atom in the main chain.

11. Furthermore, the chemically amplified positive resist composition according to claim 1, further comprising an organic solvent.

12. Furthermore, the chemically amplified positive-type resist composition according to claim 1, further comprising a photoacid generator.

13. The chemically amplified positive resist composition according to claim 12, wherein the acid strength (pKa) of the anion of the photoacid generator is -2.0 or higher.

14. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using a chemically amplified positive-type resist composition according to any one of claims 1 to 13; irradiating the resist film with a pattern using a high-energy beam; and developing the resist film irradiated with the pattern using an alkaline developer.

15. The resist pattern formation method according to claim 14, wherein the high-energy ray is an extreme ultraviolet ray or an electron ray.

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 14, wherein the substrate is a photomask blank.

18. Photomask blanks coated with a chemically amplified positive resist composition according to any one of claims 1 to 13.

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