Chemically amplified positive resist composition and resist pattern forming method

Abstract

To provide a chemically amplified positive resist composition which can form a resist film capable of forming a pattern with extremely high resolution, small LER, excellent rectangularity, and a suppressed influence of residue defects on a developer, and to provide a resist pattern forming method using the chemically amplified positive resist composition.SOLUTION: The chemically amplified positive resist composition comprises (A) a base polymer, (B) a photoacid generator, and (C) a quencher. The base polymer (A) contains a polymer containing a predetermined phenolic hydroxy group-containing unit, a predetermined aromatic ring-containing unit, and a phenolic hydroxy group-containing unit protected by a predetermined acid-labile group. All repeating units contained in the base polymer (A) are repeating units having an aromatic ring. The number of halogen atoms contained in the repeating units constituting the base polymer (A) is 3 or less.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In recent years, with the increasing integration density of integrated circuits, there is a demand for finer pattern formation, and chemically amplified resist compositions using acids as catalysts are mainly used for processing patterns of 0.2 μm or less. In addition, high-energy rays such as ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), and electron beams (EB) are used as exposure sources in this case, and EB lithography, which is used as an ultrafine processing technology, is also indispensable as a processing method for photomask blanks when producing photomasks for semiconductor manufacturing.

[0003] In EB lithography, EB writing is generally performed without using a mask. In the case of positive type, EB is sequentially irradiated on the areas other than the area to be left on the resist film, and in the case of negative type, EB is sequentially irradiated on the area to be left on the resist film. In other words, since the entire area of ​​the processing surface is finely divided, it takes more time than one-time exposure using a photomask, and a highly sensitive resist film is required to maintain throughput. In the processing of photomask blanks, which is a particularly important application, some photomask substrates have surface materials that easily affect the pattern shape of the chemically amplified resist film, such as chromium oxide and other chromium compound films formed on the photomask substrate. In order to maintain high resolution and the shape after etching, it is important to maintain the pattern profile of the resist film in a rectangular shape regardless of the type of substrate. Another important performance is to have a small line edge roughness (LER). In recent years, in order to achieve miniaturization, a multi-beam mask writing (MBMW) drawing process is sometimes used to process mask blanks. In this case, a low-sensitivity resist composition (high dose region) that is advantageous for roughness is used as the resist composition, and optimization of the resist composition in this high dose region has also been attracting attention.

[0004] Regarding the control of sensitivity and pattern profile, various improvements have been made by the selection and combination of materials used in the resist composition, process conditions, etc. One of the improvements is the suppression of acid diffusion, which has a significant effect on the resolution of the resist film. In photomask processing, it is required that the shape of the obtained resist pattern does not change depending on the time from exposure to heating. The main cause of the time-dependent change in the resist pattern shape is the diffusion of acid generated by exposure. This problem of acid diffusion is not limited to photomask processing, but has a significant effect on the sensitivity and resolution of general resist compositions as well, and has been much studied.

[0005] Patent Documents 1 and 2 disclose examples of suppressing acid diffusion and reducing LER by increasing the bulkiness of the acid generated from an acid generator. However, such acid generators do not sufficiently suppress acid diffusion, and therefore there has been a demand for the development of an acid generator with smaller acid diffusion.

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

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

[0008] As the base polymer of a positive-tone EB lithography resist composition or EUV lithography resist composition, a material is mainly used that uses an acid generated by irradiating a photoacid generator with high energy rays as a catalyst to deprotect the acid labile group masking the acidic functional group of the phenol side chain of the base polymer, thereby making it soluble in an alkaline developer. As the acid labile group, in addition to a tertiary alkyl group and a tert-butoxycarbonyl group, an acetal group has been used as an acid labile group with a relatively small activation energy (Patent Documents 4 to 8).

[0009] However, although acetal groups have the advantage of being able to produce a highly sensitive resist film, particularly in the MBMW writing process in EB lithography for producing cutting-edge photomasks at or below the 10 nm node, writing is performed in a thin region where the resist film has a thickness of 100 nm or less, and in a high-dose region where the irradiation energy is high. Therefore, if the reactivity of the acetal is high, a deprotection reaction will occur even in the unexposed portions of the resist film, resulting in a problem of degradation of resolution and roughness, which are particularly important in positive resist compositions.

[0010] In addition, in the development process of photomask manufacturing, there is a tendency to use more developer and the development conditions are stronger than those of so-called wafer-based KrF, ArF or EUV lithography in order to minimize mask defects. Resist design suited to such a strong development process is important, and there has been a demand for the development of a resist composition that can achieve high resolution, reduced roughness, and reduced development residue defects even in the latest generation. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2009-53518 A [Patent Document 2] JP 2010-100604 A [Patent Document 3] JP 2011-22564 A [Patent Document 4] Patent No. 3981830 [Patent Document 5] Patent No. 5385017 [Patent Document 6] International Publication No. 2019-167419 [Patent Document 7] Patent No. 6987873 [Patent Document 8] International Publication No. 2019-044259 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in order to solve the above-mentioned problems, and has an object to provide a chemically amplified positive resist composition that is capable of forming a resist film that has extremely high resolution, small LER, and excellent rectangularity, and is capable of forming a pattern in which the influence of residue defects on a developer is suppressed, and a method of forming a resist pattern that uses the chemically amplified positive resist composition. [Means for solving the problem]

[0013] As a result of intensive research into achieving the above-mentioned object, the inventors have found that by preparing a resist composition that contains a base polymer using an acetal-type acid labile group having a structure in which an aromatic ring is bonded to a carbon atom to which two oxygen atoms are bonded, a photoacid generator, and a quencher, and in which the content ratio of the photoacid generator to the quencher is controlled, it is possible to obtain a pattern that exhibits good resolution, pattern shape, and roughness even in a high dose region, and in which the influence of residue defects is suppressed, which has led to the completion of the present invention.

[0014] That is, the present invention provides the following chemically amplified positive resist composition and method of forming a resist pattern. 1. A chemically amplified positive resist composition comprising: (A) a base polymer; (B) a photoacid generator; and (C) a quencher, (A) the base polymer comprises a polymer containing a phenolic hydroxy group-containing unit represented by the following formula (A1), an aromatic ring-containing unit represented by any one of the following formulae (A2) to (A4), and a phenolic hydroxy group-containing unit protected by an acid labile group represented by formula (A5), (A) all of the repeating units contained in the base polymer have an aromatic ring; (A) The number of halogen atoms contained in the repeating unit constituting the base polymer is 3 or less. A chemically amplified positive resist composition. [ka] (In the formula, a1 is an integer that satisfies 0≦a1≦5+2(a3)−a2. a2 is an integer of 1 to 3. a3 is an integer of 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 in the main chain. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a portion of -CH2- in 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. [ka] (In the formula, b and c each independently represent an integer of 0 to 4; d1 represents an integer of 0 to 5; and d2 represents an integer of 0 to 2.) R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a portion of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. R 2 and R 3each independently represents a hydroxy group, a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom. R 4 represents 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 may also represent a hydroxy group when d2 is 1 or 2. [ka] [In the formula, e1 is an integer that satisfies 0≦e1≦5+2(e3)−e2; e2 is an integer of 1 to 3; and e3 is an integer of 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a portion of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. R 5 represents 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 ALis an acetal type acid labile group represented by the following formula (AL-1) when e2 is 1, and is a hydrogen atom or an acetal type acid labile group represented by the following formula (AL-1) when e2 is 2 or more, provided that at least one of them is an acetal type acid labile group represented by the following formula (AL-1). [ka] (In the formula, f1 is an integer of 0 to 2. f2 is an integer that satisfies 0≦f2≦5+2(f1). R 6 represents 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. R L1 is a hydrocarbyl group having 1 to 30 carbon atoms. The dashed lines represent bonds.) 2. The chemically amplified positive resist composition according to 1, wherein the phenolic hydroxy group-containing unit is a repeating unit represented by the following formula (A1-1): [ka] (In the formula, R A and a2 are the same as above.) 3. The chemically amplified positive resist composition of 1 or 2, wherein the acid labile group-protected phenolic hydroxy group-containing unit is a repeating unit represented by the following formula (A5-1): [ka] (In the formula, R A , R 6 , f1, f2 and R L1 is the same as above.) 4. (B) A chemically amplified positive resist composition according to any one of 1 to 3, wherein the acid strength (pKa) of the acid generated by the photoacid generator is −3.0 or higher. 5. The chemically amplified positive resist composition according to any one of 1 to 4, wherein the content ratio of the photoacid generator (B) to the quencher (C) ((B) / (C)) is less than 3 in terms of mass ratio. 6. The chemically amplified positive resist composition according to any one of 1 to 5, wherein (B) the photoacid generator is an onium salt compound containing an anion represented by the following formula (B-1) or (B-2): [ka] (In the formula, m1 and m2 each independently represent an integer of 0 to 2. m3 represents an integer of 1 to 5 when m1=0, an integer of 1 to 7 when m1=1, and an integer of 1 to 9 when m1=2. m4 represents an integer of 0 to 5 when m2=0, an integer of 0 to 7 when m2=1, and an integer of 0 to 9 when m2=2. L 1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a carbonate bond or a carbamate bond. R 11 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 11 , L 1 is bonded to the carbon atom adjacent to the carbon atom to which m3 is bonded. Also, when m3 is 2 or more, multiple R 11 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 12 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 12 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 is the carbon atom C of the adjacent aromatic ring. 1 and C 2 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. W 2 is the carbon atom C of the adjacent aromatic ring. 3 and C4 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom.) [ka] (In the formula, n1 and n2 are each independently an integer of 0 to 2. n3 is an integer of 1 to 4 when n2=0, an integer of 1 to 6 when n2=1, and an integer of 1 to 8 when n2=2. n4 is an integer of 0 to 3 when n2=0, an integer of 0 to 5 when n2=1, and an integer of 0 to 7 when n2=2. However, n3+n4 is an integer of 1 to 4 when n2=0, an integer of 1 to 6 when n2=1, and an integer of 1 to 8 when n2=2. n5 is an integer of 1 to 5 when n1=0, an integer of 1 to 7 when n1=1, and an integer of 1 to 9 when n1=2. R 21 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 21 , L 11 is bonded to the carbon atom adjacent to the carbon atom to which n5 is bonded. Also, when n5 is 2 or more, multiple R 21 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 22 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and when n4 is 2 or more, 22 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F1 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated thioalkoxy group having 1 to 6 carbon atoms. L 11 and L 12 is a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. X Lis a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. 7. (B) The chemically amplified positive resist composition according to 6, wherein the photoacid generator is an onium salt compound having no fluorine atom in the anion. 8. The chemically amplified positive resist composition according to any one of 1 to 7, further comprising a fluorine atom-containing polymer which contains at least one selected from the group consisting of a repeating unit represented by the following formula (D1), a repeating unit represented by the following formula (D2), a repeating unit represented by the following formula (D3), and a repeating unit represented by the following formula (D4), and which may further contain at least one selected from the group consisting of a repeating unit represented by the following formula (D5) and a repeating unit represented by the following formula (D6). [ka] (In the formula, x is 1, 2, or 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. k is 1, 2, or 3. R B each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R C are each independently a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 each independently represents a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; R 103 , R 106 , R 107 and R 108 When is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. R 109represents a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a heteroatom interposed between the carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a group containing a heteroatom interposed between the carbon-carbon bonds. R 111 represents a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a portion of the -CH2- in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. Z 1 is a (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 -It is. 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * is a bond to a carbon atom in the main chain.) 9. Any one of the chemically amplified positive resist compositions according to 1 to 8, further comprising (E) an organic solvent. 10. The chemically amplified positive resist composition according to any one of 1 to 9, wherein the dissolution rate of the base polymer in an alkaline developer is 5 nm / min or less. 11. The chemically amplified positive resist composition according to any one of 1 to 10, wherein the dissolution rate of the unexposed area of ​​a resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less. 12. Any one of the chemically amplified positive resist compositions 1 to 11 for use in EB lithography. 13. A method for forming a resist pattern, comprising the steps of forming a resist film on a substrate using any one of the chemically amplified positive resist compositions according to 1 to 12, irradiating the resist film with a pattern using EUV or EB, and developing the resist film irradiated with the pattern using an alkaline developer. 14. The method for forming a resist pattern according to claim 13, wherein the outermost surface of the substrate is made of a material containing at least one element selected from the group consisting of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin. 15. The method for forming a resist pattern according to 13 or 14, wherein the substrate is a transmission type or a reflection type mask blank. 16. A transmission or reflection mask blank coated with any one of the chemically amplified positive resist compositions according to 1 to 12. Effect of the Invention

[0015] The chemically amplified positive resist composition of the present invention is capable of forming a pattern with high resolution, small LER, and excellent rectangularity with a good shape after exposure, and of forming a pattern in which the influence of residue defects on the developer is suppressed, and is suitable as a resist composition for forming an EB-sensitive resist film used in processing semiconductors, photomask blanks, etc. Furthermore, a pattern formation method using the chemically amplified positive resist composition of the present invention is capable of forming a pattern with high resolution, etching resistance, reduced LER, and a pattern in which the influence of residue defects on the developer is suppressed, and therefore can be suitably used in microfabrication techniques, in particular EUV lithography and EB lithography. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The present invention will be described in detail below. In the following description, some structures represented by chemical formulas may have asymmetric carbons and may have enantiomers or diastereomers, but in such cases, one formula will be used to represent these isomers. These isomers may be used alone or as a mixture.

[0017] [Chemically amplified positive resist composition] The chemically amplified positive resist composition of the present invention comprises (A) a base polymer, (B) a photoacid generator, and (C) a quencher.

[0018] [(A) Base polymer] The base polymer of the component (A) includes a polymer containing a phenolic hydroxy group-containing unit represented by the following formula (A1) (hereinafter also referred to as repeating unit A1). [ka]

[0019] In formula (A1), a1 is an integer satisfying 0≦a1≦5+2(a3)−a2. a2 is an integer from 1 to 3. a3 is an integer from 0 to 2.

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

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

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

[0023] In formula (A1), 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. The saturated hydrocarbyl group, and the saturated hydrocarbyl carbonyloxy group and the saturated hydrocarbyloxy group may be linear, branched, or cyclic, and specific examples thereof 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 groups. When the number of carbon atoms is equal to or less than the upper limit, the solubility in an alkaline developer is good. When a1 is 2 or more, each R 1 may be the same as or different from each other.

[0024] X 1 and A 1 When both are single bonds, preferred examples of the repeating unit A1 include units derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, etc. Among these, the repeating unit represented by the following formula (A1-1) is more preferred. [ka] (In the formula, R A and a2 are the same as above.)

[0025] X 1 When R is other than a single bond, preferred examples of the repeating unit A1 include, but are not limited to, those shown below. A is the same as above. [ka]

[0026] [ka]

[0027] The repeating unit A1 is preferably introduced in the range of 30 to 90 mol %, and more preferably in the range of 60 to 85 mol %, of the total repeating units of the polymer contained in the base polymer. However, when the repeating unit A1 contains at least one of the repeating units represented by formula (A2) and the repeating unit represented by formula (A3), which give higher etching resistance to the polymer described later, and the unit has a phenolic hydroxyl group as a substituent, the ratio of the repeating unit A1 is preferably within the above range. The repeating unit A1 may be used alone or in combination of two or more types.

[0028] The polymer further contains at least one selected from an aromatic ring-containing unit represented by the following formula (A2) (hereinafter also referred to as repeating unit A2), an aromatic ring-containing unit represented by the following formula (A3) (hereinafter also referred to as repeating unit A3), and an aromatic ring-containing unit represented by the following formula (A4) (hereinafter also referred to as repeating unit A4). [ka]

[0029] In the formulae (A2) and (A3), b and c each independently represent an integer of 0 to 4.

[0030] In formulas (A2) and (A3), R 2 and R 3 are each independently a hydroxy group, a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, and saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic. When b is 2 or more, each R2 may be the same or different. When c is 2 or more, each R 3 may be the same as or different from each other.

[0031] In formula (A4), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. d1 is an integer of 0 to 5. d2 is an integer of 0 to 2.

[0032] In formula (A4), R 4 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 may be a hydroxy group when d2 is 1 or 2. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, saturated hydrocarbyloxyhydrocarbyl group and saturated hydrocarbylthiohydrocarbyl group may be linear, branched or cyclic. When d1 is 2 or more, each R 4 may be the same as or different from each other.

[0033] In formula (A4), X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain.

[0034] In formula (A4), A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic. Specific examples thereof include A in formula (A1): 1 Examples of the examples are similar to those given in the description of .

[0035] When the repeating units A2 to A4 are used, in addition to the etching resistance of the aromatic ring, the addition of a ring structure to the main chain provides the effect of improving resistance to EB irradiation during etching and pattern inspection.

[0036] In order to obtain the effect of improving etching resistance, the repeating units A2 to A4 are preferably introduced in an amount of 5 mol % or more of the total repeating units of the polymer contained in the base polymer. The repeating units A2 to A4 are preferably introduced in an amount of 25 mol % or less of the total repeating units of the polymer contained in the base polymer, and more preferably introduced in an amount of 20 mol % or less. When there is no functional group or when the functional group is other than a hydroxy group, it is preferable that the amount introduced is 25 mol % or less, since there is no risk of development defects occurring. The repeating units A2 to A4 may be used alone or in combination of two or more.

[0037] Of all the repeating units in the base polymer, the content of at least one selected from the repeating unit A1 and the repeating units A2 to A4 is preferably 60 mol % or more, and more preferably 70 mol % or more.

[0038] The polymer further contains a phenolic hydroxy group-containing unit protected with an acid labile group represented by the following formula (A5) (hereinafter also referred to as repeating unit A5). [ka]

[0039] In formula (A5), R A is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. e1 is an integer that satisfies 0≦e1≦5+2(e3)-e2. e2 is an integer from 1 to 3. e3 is an integer from 0 to 2.

[0040] In formula (A5), X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain.

[0041] In formula (A5), A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and a part of -CH2- in the saturated hydrocarbylene group may be substituted with -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic. Specific examples thereof include A in formula (A1): 1 Examples of the examples are similar to those given in the description of .

[0042] In formula (A5), R 5 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. The saturated hydrocarbyl group, the saturated hydrocarbylcarbonyloxy group, and the saturated hydrocarbyloxy group may be linear, branched, or cyclic, and specific examples thereof include R 1 When the number of carbon atoms is equal to or less than the upper limit, the solubility in an alkaline developer is good. When e1 is 2 or more, each R 5 may be the same as or different from each other.

[0043] In formula (A5), R AL is an acetal type acid labile group represented by the following formula (AL-1) when e2 is 1, and is a hydrogen atom or an acetal type acid labile group represented by the following formula (AL-1) when e2 is 2 or more, provided that at least one of them is an acetal type acid labile group represented by the following formula (AL-1). [ka] (The dashed lines represent bonds.)

[0044] In formula (AL-1), f1 is an integer of 0 to 2. f2 is an integer that satisfies 0≦f2≦5+2(f1).

[0045] In formula (AL-1), R 6 represents 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.

[0046] R 6 is appropriately selected according to the design of the sensitivity of the decomposable group to acid. In order to further optimize the acetal elimination reaction, various substituents such as hydrogen atoms, electron donating groups, and electron withdrawing groups can be selected, but it is preferable to select an electron withdrawing group in terms of ease of control of elimination reactivity. In addition, when a halogen atom is selected, it is preferable that the number of halogen atoms is 3 or less from the viewpoint of reactivity control, compatibility with an alkaline developer, and suppression of development defects, and it is more preferable that the number of iodine atoms is 2 or less from the viewpoint of solubility in a resist solvent.

[0047] R AL The structural feature of the acetal-type acid labile group represented by the formula (1) is that an aromatic ring is bonded to the carbon atom to which two oxygen atoms are bonded. Compared to alkyl and cycloalkyl groups, it is easier to optimize the acid elimination reaction and also improves etching resistance.

[0048] In formula (AL-1), R L1 is a hydrocarbyl group having 1 to 30 carbon atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. A carbon atom forming the hydrocarbyl group may be replaced with a heteroatom such as an oxygen atom or a sulfur atom to form an ether bond or a sulfide bond. Specific examples thereof include saturated hydrocarbyl groups having 1 to 30 carbon atoms and aryl groups having 6 to 30 carbon atoms. In particular, in order to obtain higher resolution in the formation of fine patterns, R L1 R is preferably a hydrocarbyl group having 1 to 6 carbon atoms. L1When is a hydrocarbyl group having 1 to 6 carbon atoms, the alcohol generated after the deprotection reaction with an acid proceeds is water-soluble, and therefore dissolves in an alkaline developer when a positive pattern is formed using the developer, thereby making it possible to suppress residual defects in exposed areas.

[0049] R L1 Specific examples of the group represented by the formula include, but are not limited to, those shown below. In the following formula, * represents a bond to the adjacent -O-. [ka]

[0050] [ka]

[0051] Specific examples of the acetal-type acid labile group represented by formula (AL-1) include, but are not limited to, those shown below. L1 is the same as above, and the dashed lines represent bonds. [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] The phenolic hydroxy group-containing unit protected with an acid labile group is preferably one represented by the following formula (A5-1). [ka] (In the formula, R A , R 6 , f1, f2 and R L1 is the same as above.)

[0057] Methods for protecting a polymer with an acetal-type acid labile group after polymerization include a method using a vinyl ether and an acid catalyst, and a method using an acetalizing agent having a haloalkoxy group together with a base. Here, the method using an acetalizing agent having a haloalkoxy group together with a base is preferred.

[0058] The method of using an acetalizing agent having a haloalkoxy group together with a base is a method of dropping an acetalizing agent having a haloalkoxy group in the presence of a basic compound such as triethylamine, etc. The reaction temperature is −20 to 50° C., and the reaction time is 0.2 to 10 hours, preferably 0.5 to 6 hours.

[0059] The repeating units protected with the acetal type acid labile group are preferably introduced in an amount of 10 to 40 mol %, more preferably 10 to 30 mol %, and even more preferably 20 to 30 mol %, of all repeating units of the polymer contained in the base polymer.

[0060] The base polymer may contain a polymer having a known acid labile group other than the acetal-type acid labile group represented by formula (AL-1), such as a tertiary alkyl group or a tert-butoxycarbonyl group. In this case, the polymer having an acid labile group other than the acetal-type acid labile group represented by formula (AL-1) preferably contains a repeating unit having an acid labile group other than the acetal-type acid labile group represented by formula (AL-1) and a repeating unit A1, and if necessary, repeating units A2 to A4. In order to exert the effects of the present invention, it is preferable that the proportion of the base polymer having an acetal-type acid labile group is 50% or more of all the base polymers contained in the chemically amplified positive resist composition of the present invention.

[0061] The number of halogen atoms contained in the repeating units constituting the base polymer is preferably not more than 3. If the number of halogen atoms is 4 or more, the solubility in an alkaline developer decreases, which may cause development residues.

[0062] The acetal-type acid labile group also has the effect of suppressing the influence of back scattering during EB writing. 2 More than 80μC / cm 2 More preferably, 100 μC / cm 2 In the above sensitivity region, the pattern shape does not become inversely tapered and exhibits rectangular performance.

[0063] The base polymer preferably has a weight average molecular weight (Mw) of 1000 to 20000, more preferably 4000 to 7000. If Mw is 1000 or more, there is no risk of the phenomenon that the head of the pattern becomes rounded, the resolution decreases, and the LER deteriorates, as has been known in the past. On the other hand, if Mw is 20000 or less, there is no risk of the LER deteriorates, especially when a pattern having a pattern line width of 100 nm or less is formed. In the present invention, Mw is a value measured in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran (THF) or dimethylformamide (DMF) as a solvent.

[0064] The base polymer preferably has a narrow molecular weight distribution (Mw / Mn) of 1.0 to 2.0, preferably 1.0 to 1.8, and more preferably 1.0 to 1.6, such that foreign matter is not generated on the pattern and the shape of the pattern is not deteriorated after development.

[0065] In addition, as the base polymer design, the dissolution rate in an 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 the advanced generation, when the coating film on the substrate is in the thin film region (100 nm or less), the effect of pattern film loss due to alkaline development becomes large, and if the alkaline dissolution rate of the polymer is more than 10 nm / min, the pattern collapses and fine patterns cannot be formed. This is particularly noticeable in the production of photomasks that are required to be free of defects, since the development process tends to be strong. In addition, in the present invention, the dissolution rate of the base polymer in an alkaline developer is a value calculated from the amount of film loss when a polymer solution (polymer concentration: 16.7 mass%, solvent: propylene glycol monomethyl ether acetate (PGMEA)) is spin-coated on an 8-inch silicon wafer, baked at 100°C for 90 seconds to form a film with a thickness of 1000 nm, and then developed with a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution at 23°C for 100 seconds.

[0066] [(B) Photoacid generator] The chemically amplified positive resist composition of the present invention may contain a photoacid generator. The photoacid generator is not particularly limited as long as it is a compound that generates an acid upon exposure to high-energy radiation. Suitable photoacid generators include sulfonium salts, iodonium salts, sulfonyldiazomethane, N-sulfonyloxyimide, and oxime-O-sulfonate type acid generators.

[0067] Specific examples of the photoacid generator include nonafluorobutanesulfonate, the partially fluorinated sulfonates described in JP-A-2012-189977, paragraphs

[0247] to

[0251] , the partially fluorinated sulfonates described in JP-A-2013-101271, paragraphs

[0261] to

[0265] , the ones described in JP-A-2008-111103, paragraphs

[0122] to

[0142] , and the ones described in JP-A-2010-215608, paragraphs

[0080] to

[0081] , and fluorobenzenesulfonic acid type. Among the specific examples, arylsulfonate type or alkane sulfonate type photoacid generators are preferred because they generate an acid of suitable strength for deprotecting the acid labile group of the repeating unit represented by formula (A5).

[0068] As such a photoacid generator, an onium salt compound having an anion of the structure shown below is preferred. [ka]

[0069] [ka]

[0070] [ka]

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] As the photoacid generator of the component (B), an onium salt compound containing an anion represented by the following formula (B-1) is also preferred. [ka]

[0078] In formula (B-1), m1 and m2 are each independently an integer of 0 to 2. When m1=0, it represents a benzene ring, when m1=1, it represents a naphthalene ring, and when m1=2, it represents an anthracene ring, but from the viewpoint of solvent solubility, m1=0, that is, a benzene ring, is preferred. Also, from the viewpoint of solvent solubility, m2 is preferably 0.

[0079] In formula (B-1), m3 is an integer of 1 to 5 when m1 = 0, an integer of 1 to 7 when m1 = 1, and an integer of 1 to 9 when m1 = 2. m4 is an integer of 0 to 5 when m2 = 0, an integer of 0 to 7 when m2 = 1, and an integer of 0 to 9 when m2 = 2.

[0080] In formula (B-1), L 1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a carbonate bond or a carbamate bond. Among these, an ether bond, an ester bond or a sulfonate ester bond is preferred, and a sulfonate ester bond is more preferred.

[0081] In formula (B-1), R 11 is an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 11 , L 1 Specific examples of the hydrocarbyl group include an isopropyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, a cyclopentyl group, a cyclohexyl group, a 2-ethylhexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, a tricyclo[5.2.1.0 2,6 ] decyl group, adamantyl group, and other aliphatic cyclic hydrocarbon groups having 3 to 20 carbon atoms; phenyl group, naphthyl group, anthracenyl group, and other aryl groups; and groups obtained by combining these groups, but are not limited thereto. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom or an iodine atom is preferable. When m3 is 2 or more, each R 11may be the same as or different from each other.

[0082] Also, when m3 is 2 or more, multiple R 11 However, they may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0083] In formula (B-1), R 12 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, or an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, or a tricyclo[5.2.1.0 2,6 ] decyl group, adamantyl group, adamantylmethyl group, and other cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms; phenyl group, naphthyl group, anthracenyl group, and other aryl groups having 6 to 20 carbon atoms. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom or an iodine atom is preferable. When m4 is 2 or more, each R 12may be the same as or different from each other.

[0084] Also, when m4 is 2 or more, multiple R 12 However, they may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0085] In formula (B-1), W 1 is the carbon atom C of the adjacent aromatic ring. 1 and C 2 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. The ring may be a monocyclic or polycyclic ring. 2 is the carbon atom C of the adjacent aromatic ring. 3 and C 4 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. The ring may be a monocyclic ring or a polycyclic ring.

[0086] W in formula (B-1) 1 and W 2 Examples of the structure in which L and an adjacent aromatic ring are condensed include, but are not limited to, those shown below. In the following formula, the dashed line indicates L 1 It is a combination with. [ka]

[0087] R in formula (B-1) 11 Examples of the structure in which L is bonded to an aromatic ring include, but are not limited to, those shown below. In the following formula, the dashed line represents L 1 It is a combination with. [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] [ka]

[0093] The anion represented by formula (B-1) is preferably an anion represented by the following formula (B-1-1). [ka] (In the formula, m2, m3, m4, L 1 , R 11 , R 12 , W 1 and W 2 is the same as above.)

[0094] The anion represented by formula (B-1-1) is preferably an anion represented by the following formula (B-1-2). [ka] (In the formula, m3, m4, R 11 , R 12 and W 1 is the same as above.)

[0095] Particularly preferred examples of the anion represented by formula (B-1) include, but are not limited to, those shown below. [ka]

[0096]

change

[0097]

change

[0098]

change

[0099]

change

[0100]

change

[0101]

change

[0102]

change

[0103]

change

[0104]

change

[0105]

change

[0106]

change

[0107]

change

[0108]

change

[0109]

change

[0110]

change

[0111]

change

[0112]

change

[0113]

change

[0114]

change

[0115]

change

[0116]

change

[0117] [ka]

[0118] [ka]

[0119] The onium salt containing the anion represented by formula (B-1) is an onium salt of sulfonic acid not substituted with fluorine atoms, and can generate an acid of moderate strength by irradiation with high energy rays. In addition, it has a structural feature that it has a ring structure further condensed to the aromatic ring bonded to the sulfo group of the anion, and has another aromatic ring structure containing a bulky substituent. The steric hindrance between these two aromatic rings suppresses the degree of rotational freedom of the bond connecting the aromatic rings, thereby restricting excessive acid diffusion of the generated acid. Furthermore, since the onium salt of the present invention has sufficient liposolubility, it is easy to manufacture and handle. Due to these effects, an acid with moderate acid strength and acid diffusion controlled can be generated in the resist film, so that a pattern with good resolution and small LER can be obtained even in a fine pattern, and a positive resist composition using an alkaline developer has a moderate dissolution inhibition property to obtain a pattern with good rectangularity.

[0120] As the photoacid generator of the component (B), an onium salt compound containing an anion represented by the following formula (B-2) is also preferred. [ka]

[0121] In formula (B-2), n1 and n2 each independently represent an integer of 0 to 2. n3 represents an integer of 1 to 4 when n2=0, an integer of 1 to 6 when n2=1, and an integer of 1 to 8 when n2=2.

[0122] In formula (B-2), n4 is an integer from 0 to 3 when n2=0, an integer from 0 to 5 when n2=1, and an integer from 0 to 7 when n2=2. However, n3+n4 is an integer from 1 to 4 when n2=0, an integer from 1 to 6 when n2=1, and an integer from 1 to 8 when n2=2.

[0123] In formula (B-2), n5 is an integer of 1 to 5 when n1=0, an integer of 1 to 7 when n1=1, and an integer of 1 to 9 when n1=2.

[0124] In formula (B-2), R 21 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 21 is the L 11 Specific examples of the hydrocarbyl group include branched alkyl groups such as an isopropyl group, a sec-butyl group, a tert-butyl group, a tert-pentyl group, and a 2-ethylhexyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, an oxanorbornyl group, a tricyclo[5.2.1.0 2,6] decyl group, adamantyl group, and other cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms; phenyl group, naphthyl group, anthracenyl group, and other aryl groups; and groups obtained by combining these groups, but are not limited thereto. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom or an iodine atom is preferable. When n5 is 2 or more, each R 21 may be the same as or different from each other.

[0125] Also, when n5 is 2 or more, multiple R 21 However, they may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0126] R in formula (B-2) 21 Examples of the structure in which L is bonded to an aromatic ring include, but are not limited to, those shown below. In the following formula, the dashed line represents L 11 It is a combination with. [ka]

[0127] [ka]

[0128] [ka]

[0129] [ka]

[0130] [ka]

[0131] [ka]

[0132] [ka]

[0133] In formula (B-2), R 22 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group, or an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, or a tricyclo[5.2.1.0 2,6] decyl group, adamantyl group, adamantylmethyl group, and other cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms; phenyl group, naphthyl group, anthracenyl group, and other aryl groups having 6 to 20 carbon atoms. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom, or a halogen atom, and some of -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a halogen atom, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom or an iodine atom is preferable. When n4 is 2 or more, each R 22 may be the same as or different from each other.

[0134] Also, when n4 is 2 or more, multiple R 22 However, they may be bonded to each other to form a ring together with the carbon atom to which they are bonded. The ring is preferably a 5- to 8-membered ring.

[0135] In formula (B-2), R F1 R are each independently a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated thioalkoxy group having 1 to 6 carbon atoms. F1 is preferably a fluorine atom, a trifluoromethyl group, a difluoromethyl group, a trifluoromethoxy group, a difluoromethoxy group, a trifluoromethylthio group, or a difluoromethylthio group, and more preferably a fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group. By containing a fluorine atom, the acid strength of the generated acid is improved, so that the deprotection reaction proceeds smoothly. When n3 is 2 or more, each R F1 may be the same as or different from each other.

[0136] In formula (B-2), L 11and L 12 are each independently a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. Among these, an ether bond, an ester bond or a sulfonate ester bond is preferred, and an ether bond or a sulfonate ester bond is more preferred.

[0137] In formula (B-2), X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom. The hydrocarbylene group may be linear, branched or cyclic, and specific examples thereof include an alkanediyl group, a cyclic saturated hydrocarbylene group, etc. Specific examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, etc.

[0138] X L Specific examples of the hydrocarbylene group having 1 to 40 carbon atoms and optionally containing a heteroatom, represented by the following formula, include, but are not limited to, those shown below. In the following formula, * represents L 11 and L 12 Represents a bond with . [ka]

[0139] [ka]

[0140] [ka]

[0141] [ka]

[0142] Of these, X L -0~X L -22 and X L -47~XL -58 is preferred.

[0143] The acid generator represented by formula (B-2) is preferably one represented by the following formula (B-2-1). [ka] (In the formula, n1~n5, R 21 , R 22 , R F1 , L 11 and X L is the same as above.)

[0144] Specific examples of the anion represented by formula (B-2) include, but are not limited to, those shown below. [ka]

[0145] [ka]

[0146] [ka]

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151]

change

[0152]

change

[0153]

change

[0154]

change

[0155]

change

[0156]

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[0157]

change

[0158]

change

[0159]

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[0160]

change

[0161]

change

[0162]

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[0163]

change

[0164]

change

[0165]

change

[0166]

change

[0167]

change

[0168]

change

[0169]

change

[0170]

change

[0171]

change

[0172] [ka]

[0173] [ka]

[0174] [ka]

[0175] [ka]

[0176] As the photoacid generator, component (B), an onium salt compound containing an anion represented by the following formula (B-3) is also preferred. [ka]

[0177] In formula (B-3), p is 1, 2 or 3. q is an integer of 1 to 5. r is an integer of 0 to 3. s1 is 0 or 1.

[0178] In formula (B-3), L 21 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond.

[0179] In formula (B-3), L 22 is an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond.

[0180] In formula (B-3), L 23represents a single bond or a hydrocarbylene group having 1 to 20 carbon atoms when p is 1, and represents a (p+1)-valent hydrocarbon group having 1 to 20 carbon atoms when p is 2 or 3, and the hydrocarbylene group and the (p+1)-valent hydrocarbon group may contain at least one bond selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group.

[0181] L 23 The hydrocarbylene group having 1 to 20 carbon atoms represented by the formula (1) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diyl group, and a dodecane-1,12-diyl group. alkanediyl groups having 1 to 20 carbon atoms; cyclic saturated hydrocarbylene groups having 3 to 20 carbon atoms, such as cyclopentanediyl group, cyclohexanediyl group, norbornanediyl group, and adamantanediyl group; unsaturated aliphatic hydrocarbylene groups having 2 to 20 carbon atoms, such as vinylene group and propene-1,3-diyl group; arylene groups having 6 to 20 carbon atoms, such as phenylene group and naphthylene group; and groups obtained by combining these. 23 The (p+1)-valent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include groups obtained by further removing one or two hydrogen atoms from the specific examples of the hydrocarbylene group having 1 to 20 carbon atoms described above.

[0182] In formula (B-3), Rf 1 and Rf 2 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group.

[0183] In formula (B-3), R31 is a hydroxy group, a carboxy group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, -N(R 31A )(R 31B ), -N(R 31C )-C(=O)-R 31D Or -N(R 31C )-C(=O)-OR 31D R 31A and R 31B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 31C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 31D is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0184] R 31 , R 31A , R 31B and R 31C The saturated hydrocarbyl group having 1 to 6 carbon atoms represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups; and cyclic saturated hydrocarbyl groups having 3 to 6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl groups. 31 Examples of the saturated hydrocarbyl moiety of the saturated hydrocarbyloxy group having 1 to 6 carbon atoms represented by the formula (I) include the same as the specific examples of the saturated hydrocarbyl group described above, and R 31 Examples of the saturated hydrocarbyl moiety of the saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms represented by the following formula include those having 1 to 5 carbon atoms among the specific examples of the saturated hydrocarbyl groups having 1 to 6 carbon atoms mentioned above.

[0185] R 31DThe unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include alkenyl groups having 2 to 8 carbon atoms, such as a vinyl group, a propenyl group, a butenyl group, or a hexenyl group; alkynyl groups having 2 to 8 carbon atoms, such as an ethynyl group, a propynyl group, or a butynyl group; and cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 8 carbon atoms, such as a cyclohexenyl group or a norbornenyl group.

[0186] In formula (B-3), R 32 represents a saturated hydrocarbylene group having 1 to 20 carbon atoms or an arylene group having 6 to 20 carbon atoms, some or all of the hydrogen atoms of the saturated hydrocarbylene group may be substituted with halogen atoms other than fluorine atoms, and some or all of the hydrogen atoms of the arylene group may be substituted with a substituent selected from a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a halogen atom, and a hydroxy group.

[0187] R 32 The hydrocarbylene group having 1 to 20 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include: 23 Examples of the hydrocarbylene group having 1 to 20 carbon atoms represented by the following formula include the same as those exemplified above.

[0188] R 32Specific examples of the arylene group having 6 to 20 carbon atoms represented by the following formula include a phenylene group, a naphthylene group, a phenanthrenediyl group, and an anthracenediyl group. The hydrocarbyl moiety of the saturated hydrocarbyl group having 1 to 20 carbon atoms and the hydrocarbyloxy group having 1 to 20 carbon atoms, which are substituents of the arylene group, may be any one of linear, branched, and cyclic, and specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an icosyl group; and cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclopropylmethyl group, a 4-methylcyclohexyl group, a cyclohexylmethyl group, a norbornyl group, and an adamantyl group. Specific examples of the arylene group having 6 to 14 carbon atoms which is the substituent of the arylene group include a phenylene group, a naphthylene group, a phenanthrenediyl group, and an anthracenediyl group.

[0189] The anion represented by formula (B-3) is preferably an anion represented by the following formula (B-3-1). [ka]

[0190] In formula (B-3-1), p, q, r, L 21 , L 23 and R 31 is the same as above. s2 is an integer of 1 to 4. R 32A is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, an aryl group having 6 to 14 carbon atoms, a halogen atom, or a hydroxy group. 32A may be the same as or different from each other.

[0191] Examples of the anion represented by formula (B-3) include, but are not limited to, those shown below. [ka]

[0192] [ka]

[0193] [ka]

[0194] [ka]

[0195] [ka]

[0196] [ka]

[0197] [ka]

[0198] [ka]

[0199] [ka]

[0200] [ka]

[0201]

change

[0202]

change

[0203]

change

[0204]

change

[0205]

change

[0206]

change

[0207]

change

[0208]

change

[0209]

change

[0210]

change

[0211]

change

[0212] [ka]

[0213] [ka]

[0214] [ka]

[0215] [ka]

[0216] [ka]

[0217] [ka]

[0218] [ka]

[0219] The cation paired with the anion of the onium salt is preferably a sulfonium cation represented by the following formula (B-4) or an iodonium cation represented by the following formula (B-5). [ka]

[0220] In formulas (B-4) and (B-5), R 41 ~R 45 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom.

[0221] R 41 ~R 45 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0222] R 41 ~R 45 The hydrocarbyl group having 1 to 20 carbon atoms represented by the formula (I) may be saturated or unsaturated, and may be linear, branched or cyclic. Specific examples thereof include alkyl groups having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an n-hexyl group, an n-octyl group, a 2-ethylhexyl group, an n-nonyl group or an n-decyl group; a cyclopentyl group, a cyclohexyl group, a cyclopentylmethyl group, a cyclopentylethyl group, a cyclopentylbutyl group, a cyclohexylmethyl group, a cyclohexylethyl group, a cyclohexylbutyl group, a norbornyl group, a tricyclo[5.2.1.0 2,6 ] cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as a decyl group, an adamantyl group, and an adamantylmethyl group; aryl groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, and an anthryl group; and groups obtained by combining these. In addition, some or all of the hydrogen atoms of the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms, and some of -CH2- of the hydrocarbyl groups may be substituted with groups containing heteroatoms, such as oxygen atoms, sulfur atoms, and nitrogen atoms, and as a result, the hydrocarbyl groups may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, carbonyl groups, ether bonds, ester bonds, sulfonate ester bonds, carbonate bonds, lactone rings, sultone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, and the like.

[0223] Also, R 41 and R 42 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. Examples of the ring formed in this case include the rings shown below. [ka] (In the formula, the dashed line represents R 43 It is a combination with .)

[0224] Specific examples of the sulfonium cation represented by formula (B-4) include, but are not limited to, those shown below. [ka]

[0225] [ka]

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] [ka]

[0230] [ka]

[0231] [ka]

[0232] [ka]

[0233]

change

[0234]

change

[0235]

change

[0236]

change

[0237]

change

[0238]

change

[0239]

change

[0240]

change

[0241]

change

[0242]

change

[0243] [ka]

[0244] [ka]

[0245] [ka]

[0246] [ka]

[0247] [ka]

[0248] [ka]

[0249] [ka]

[0250] Specific examples of the iodonium cation represented by formula (B-5) include, but are not limited to, those shown below. [ka]

[0251] [ka] Specific examples of the onium salt of the present invention include any combination of the above-mentioned anions and cations.

[0252] The acid generated by the photoacid generator preferably has a pKa of -3.0 or more, more preferably -1.0 or more. The upper limit of the pKa is preferably 2.0. The pKa value is calculated using the pKa DB in the software ACD / Chemsketch ver:9.04 manufactured by Advanced Chemistry Development, Inc.

[0253] In the chemically amplified positive resist composition of the present invention, the content of the photoacid generator (B) is preferably 1 to 30 parts by mass, and more preferably 2 to 20 parts by mass, relative to 80 parts by mass of the base polymer (A). The photoacid generator (B) may be used alone or in combination of two or more kinds.

[0254] [(C) Quencher] The chemically amplified positive resist composition of the present invention contains a quencher (acid diffusion inhibitor). In the present invention, the quencher refers to a material that traps the acid generated by the photoacid generator in the chemically amplified resist composition, thereby preventing the acid from diffusing into unexposed areas and forming a desired pattern.

[0255] The quencher may be a conventional basic compound. Examples of conventional basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, nitrogen-containing compounds having a sulfonyl group, nitrogen-containing compounds having a hydroxy group, nitrogen-containing compounds having a hydroxyphenyl group, alcoholic nitrogen-containing compounds, amides, imides, and carbamates. In particular, the primary, secondary, and tertiary amine compounds described in paragraphs

[0146] to

[0164] of JP-A-2008-111103, particularly amine compounds having a hydroxy group, an ether bond, an ester bond, a lactone ring, a cyano group, or a sulfonic acid ester bond, or compounds having a carbamate group described in JP-A-3790649 are preferred. Preferable examples include tris[2-(methoxymethoxy)ethyl]amine, tris[2-(methoxymethoxy)ethyl]amine-N-oxide, dibutylaminobenzoic acid, morpholine derivatives, imidazole derivatives, etc. By adding such a basic compound, for example, it is possible to further suppress the diffusion rate of the acid in the resist film and correct the shape.

[0256] Further, the quencher may be an onium salt such as a sulfonium salt, an iodonium salt, or an ammonium salt of a carboxylic acid not fluorinated at the α-position, as described in JP-A-2008-158339. A sulfonic acid, an imide acid, or a methide acid fluorinated at the α-position is necessary for deprotecting an acid labile group, but a carboxylic acid not fluorinated at the α-position is released by salt exchange with an onium salt not fluorinated at the α-position. A carboxylic acid not fluorinated at the α-position hardly undergoes a deprotection reaction, and therefore functions as a quencher.

[0257] An example of an onium salt of a carboxylic acid not fluorinated at the α-position is one represented by the following formula (C1). [ka]

[0258] In formula (C1), R 51 represents a hydrocarbyl group having 1 to 40 carbon atoms which may contain a hydrogen atom or a heteroatom, but excludes those in which the hydrogen atom bonded to the carbon atom at the α-position of the carboxy group is substituted with a fluorine atom or a fluoroalkyl group.

[0259] R 51 The hydrocarbyl group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, 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 having 3 to 40 carbon atoms, such as a decyl group, an adamantyl group, and an adamantylmethyl group; alkenyl groups having 2 to 40 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated aliphatic hydrocarbyl groups having 3 to 40 carbon atoms, such as a cyclohexenyl group; a phenyl group, a naphthyl group, an alkylphenyl group (2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, 4-ethylphenyl group, 4-tert-butylphenyl group, 5-butylphenyl group, 6-butylphenyl group, 7-butylphenyl group, 8-butylphenyl group, 9-butylphenyl group, 10-butylphenyl group, 11-butylphenyl group, 12-butylphenyl group, 13-butylphenyl group, 14-butylphenyl group, 15-butylphenyl group, 16-butylphenyl group, 17-butylphenyl group, 18-butylphenyl group, 19-butylphenyl group, 20-butylphenyl group, 21-butylphenyl group, 22-butylphenyl group, 23-butylphenyl group, 24-butylphenyl group, 25-butylphenyl group, 26-butylphenyl group, 27-butylphenyl group, 28-butylphenyl group, 29-butylphenyl group, 30-butylphenyl group, 31-butylphenyl group, 32-butylphenyl group, 33-butylphenyl group, 34-butylphenyl group, 35-butylphenyl group, 36-butylphenyl group, 37-butylphenyl group, 38-butylphenyl group, 39-butylphenyl group, 40-butylphenyl group, 41-butylphenyl group, 42-butylphenyl group, 43-butylphenyl group, 44-butylphenyl group, 45-butylphenyl group, 46-butylphenyl group, 4 Examples of such aryl groups include aryl groups having 6 to 40 carbon atoms, such as arylphenyl groups (e.g., 4-n-butylphenyl group, 4-n-butylphenyl group), di- or trialkylphenyl groups (e.g., 2,4-dimethylphenyl group, 2,4,6-triisopropylphenyl group), alkylnaphthyl groups (e.g., methylnaphthyl group, ethylnaphthyl group), dialkylnaphthyl groups (e.g., dimethylnaphthyl group, diethylnaphthyl group), and aralkyl groups having 7 to 40 carbon atoms, such as benzyl group, 1-phenylethyl group, and 2-phenylethyl group.

[0260] In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and some of the -CH2- of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom, and as a result, the hydrocarbyl group may contain a hydroxy group, a cyano group, a carbonyl group, an ether bond, a thioether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like. Examples of the hydrocarbyl group containing a heteroatom include heteroaryl groups such as a thienyl group; alkoxyphenyl groups such as a 4-hydroxyphenyl group, a 4-methoxyphenyl group, a 3-methoxyphenyl group, a 2-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-tert-butoxyphenyl group, and a 3-tert-butoxyphenyl group; alkoxynaphthyl groups such as a methoxynaphthyl group, an ethoxynaphthyl group, an n-propoxynaphthyl group, and an n-butoxynaphthyl group; dialkoxynaphthyl groups such as a dimethoxynaphthyl group and a diethoxynaphthyl group; and aryloxoalkyl groups such as a 2-aryl-2-oxoethyl group, a 2-(1-naphthyl)-2-oxoethyl group, and a 2-(2-naphthyl)-2-oxoethyl group.

[0261] In formula (C1), Mq A + is an onium cation. The onium cation is preferably a sulfonium cation, an iodonium cation or an ammonium cation, more preferably a sulfonium cation or an iodonium cation. Specific examples of the sulfonium cation include the same as those exemplified as the sulfonium cation represented by formula (B-4). Specific examples of the iodonium cation include the same as those exemplified as the iodonium cation represented by formula (B-5).

[0262] Examples of the anion of the onium salt represented by formula (C1) include, but are not limited to, those shown below. [ka]

[0263] [ka]

[0264] [ka]

[0265] As the quencher, a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (C2) can also be suitably used. [ka]

[0266] In formula (C2), t is an integer of 1 to 5. u is an integer of 0 to 3. v is an integer of 1 to 3.

[0267] In formula (C2), R 61 represents a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an amino group, a nitro group, a cyano group, or a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, in which some or all of the hydrogen atoms may be substituted with halogen atoms, or -N(R 61A )-C(=O)-R 61B Or -N(R 61A )-C(=O)-OR 61B R 61A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 61B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When u and / or v are 2 or more, each R 61 may be the same or different from each other.

[0268] In formula (C2), L31 is a single bond or a (v+1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic.

[0269] In formula (C2), R 62 , R 63 and R 64 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a hydroxy group, a carboxy group, a halogen atom, an oxo group, a cyano group, a nitro group, a sultone ring, a sulfo group, or a sulfonium salt-containing group, and some of the -CH2- of the hydrocarbyl group may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond, or a sulfonate ester bond. In addition, R 62 and R 63 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0270] Specific examples of the compound represented by formula (C2) include those described in JP 2017-219836 A. The compound represented by formula (C2) has high absorption, a high sensitizing effect, and a high acid diffusion suppressing effect.

[0271] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (C3) can also be used. [ka]

[0272] In formula (C3), R 71 ~R 74 Each independently represents a hydrogen atom, -L 41 -CO2 - or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 71 and R 72 And, R 72 and R 73 and, or R 73 and R 74 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached. 41 R is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 75 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom.

[0273] In formula (C3), ring R r is a ring containing carbon atoms and nitrogen atoms and having 2 to 6 carbon atoms, and some or all of the hydrogen atoms bonded to the carbon atoms of the ring are hydrocarbyl groups having 1 to 20 carbon atoms, or -L 41 -CO2 - and a part of the carbon atoms of the ring may be substituted with a sulfur atom, an oxygen atom, or a nitrogen atom. The ring may be an alicyclic ring or an aromatic ring, and is preferably a 5-membered or 6-membered ring, and specific examples thereof include a pyridine ring, a pyrrole ring, a pyrrolidine ring, a piperidine ring, a pyrazole ring, an imidazoline ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, an imidazoline ring, an oxazole ring, a thiazole ring, a morpholine ring, a thiazine ring, and a triazole ring.

[0274] The carboxylic acid onium salt represented by formula (C3) has at least one -L 41 -CO2 - That is, R 61 ~R 64 At least one of the following is -L 41 -CO2 - and / or ring R rAt least one of the hydrogen atoms bonded to the carbon atom of is -L 41 -CO2 - is replaced by

[0275] In formula (C3), Mq B + is a sulfonium cation, an iodonium cation, or an ammonium cation, and is preferably a sulfonium cation. Specific examples of the sulfonium cation include the same as those exemplified as the sulfonium cation represented by formula (B-4).

[0276] Examples of the anion of the compound represented by formula (C3) include, but are not limited to, those shown below. [ka]

[0277] [ka]

[0278] [ka]

[0279] [ka]

[0280] [ka]

[0281] [ka]

[0282] Alternatively, a weak acid betaine type compound may be used as the quencher, specific examples of which include, but are not limited to, those shown below. [ka]

[0283] Further examples of the quencher include polymer-type quenchers described in JP 2008-239918 A. These improve the rectangularity of the resist pattern by being oriented on the surface of the resist film. Polymer-type quenchers also have the effect of preventing film loss of the pattern and rounding of the pattern top when a protective film for immersion exposure is applied.

[0284] In the chemically amplified positive resist composition of the present invention, the content of the quencher (C) is preferably from 0.01 to 50 parts by mass, and more preferably from 0.1 to 30 parts by mass, relative to 80 parts by mass of the base polymer (A). The quencher (C) may be used alone or in combination of two or more kinds.

[0285] In the chemically amplified positive resist composition of the present invention, the content ratio of the photoacid generator to the quencher ((B) / (C)) is, in mass ratio, less than 3, preferably less than 2.5, and more preferably less than 2. When the content ratio of the photoacid generator to the quencher contained in the chemically amplified positive resist composition of the present invention is within the above range, it becomes possible to sufficiently suppress acid diffusion, and it becomes possible to obtain excellent resolution, dimensional uniformity, and pattern shape, particularly in EB lithography, which is easily affected by forward scattering and backward scattering.

[0286] [(D) Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention may contain a fluorine atom-containing polymer that contains at least one selected from the group consisting of a repeating unit represented by the following formula (D1) (hereinafter also referred to as repeating unit D1), a repeating unit represented by the following formula (D2) (hereinafter also referred to as repeating unit D2), a repeating unit represented by the following formula (D3) (hereinafter also referred to as repeating unit D3), and a repeating unit represented by the following formula (D4) (hereinafter also referred to as repeating unit D4), and may further contain at least one selected from the group consisting of a repeating unit represented by the following formula (D5) (hereinafter also referred to as repeating unit D5) and a repeating unit represented by the following formula (D6) (hereinafter also referred to as repeating unit D6), for the purposes of increasing contrast, suppressing chemical flare of acid upon irradiation with high-energy rays, shielding mixing of acid from the antistatic film in the process of applying an antistatic film material onto the resist film, and suppressing unexpected and unnecessary pattern deterioration. The fluorine atom-containing polymer also functions as a surfactant, and is therefore effective against development defects since it can prevent insoluble matter from re-adhering to the substrate during the development process. [ka]

[0287] In the formulas (D1) to (D6), x is 1, 2, or 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. k is 1, 2, or 3. R B R are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. C R is each independently a hydrogen atom or a methyl group. 101 , R 102 , R 104 and R 105 R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 103 , R 106 , R 107 and R 108 each independently represents a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; R 103 , R106 , R 107 and R 108 When R is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bonds. 109 R is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between the carbon-carbon bonds. 110 R is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group between its carbon-carbon bonds. 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and a part of the -CH2- in the saturated hydrocarbyl group may be substituted with an ester bond or an ether bond. 1 Z is a (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. 3 is a single bond, -O-, *-C(=O)-OZ 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 -It is. 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 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.

[0288] In formulas (D1) and (D2), R 101 , R 102 , R 104 and R 105The saturated hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include alkyl groups having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group or an n-decyl group; and cyclic saturated hydrocarbyl groups having 3 to 10 carbon atoms, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, an adamantyl group or a norbornyl group. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0289] In formulas (D1) to (D4), R 103 , R 106 , R 107 and R 108 The hydrocarbyl group having 1 to 15 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include an alkyl group having 1 to 15 carbon atoms, an alkenyl group having 2 to 15 carbon atoms, and an alkynyl group having 2 to 15 carbon atoms, and an alkyl group having 1 to 15 carbon atoms is preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, and an n-pentadecyl group. Examples of the fluorinated hydrocarbyl group include a group in which some or all of the hydrogen atoms bonded to the carbon atoms of the hydrocarbyl group described above are substituted with fluorine atoms.

[0290] In formula (D4), Z 1 Examples of the (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms and represented by the formula (1) include an alkyl group having 1 to 20 carbon atoms or a group in which k hydrogen atoms have been removed from a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms. 1 Examples of the (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the following formula include groups in which at least one hydrogen atom of the above-mentioned (k+1)-valent hydrocarbon group has been substituted with a fluorine atom.

[0291] Specific examples of the repeating units D1 to D4 include, but are not limited to, those shown below. B is the same as above. [ka]

[0292] [ka]

[0293] [ka]

[0294] In formula (D5), R 109 and R 110 Examples of the hydrocarbyl group having 1 to 5 carbon atoms represented by the formula (I) include an alkyl group, an alkenyl group, and an alkynyl group, with an alkyl group being preferred. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and an n-pentyl group. The carbon-carbon bonds of the hydrocarbyl group may be interrupted by a group containing a heteroatom such as an oxygen atom, a sulfur atom or a nitrogen atom.

[0295] In formula (D5), -OR 109 is preferably a hydrophilic group. In this case, R 109 is preferably a hydrogen atom, an alkyl group having 1 to 5 carbon atoms and an oxygen atom intervening between the carbon-carbon bonds, or the like.

[0296] In formula (D5), Z 2 is preferably *-C(=O)-O- or *-C(=O)-NH-. C is preferably a methyl group. 2 The presence of a carbonyl group in R improves the acid trapping ability of the antistatic film.C When the methyl group is used, the polymer becomes more rigid with a higher glass transition temperature (Tg), which suppresses the diffusion of acid. This improves the stability of the resist film over time, and the resolution and pattern shape do not deteriorate.

[0297] Examples of the repeating unit D5 include, but are not limited to, those shown below. In the following formula, R C is the same as above. [ka]

[0298] [ka]

[0299] In formula (D6), Z 3 The saturated hydrocarbylene group having 1 to 10 carbon atoms represented by the formula (I) may be linear, branched, or cyclic, and specific examples thereof include a methanediyl group, an ethane-1,1-diyl group, an ethane-1,2-diyl group, a propane-1,1-diyl group, a propane-1,2-diyl group, a propane-1,3-diyl group, a propane-2,2-diyl group, a butane-1,1-diyl group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-2,3-diyl group, a butane-1,4-diyl group, and a 1,1-dimethylethane-1,2-diyl group.

[0300] In formula (D6), R 111 The saturated hydrocarbyl group having 1 to 20 carbon atoms and at least one hydrogen atom of which is substituted with a fluorine atom, represented by the formula (I) may be linear, branched or cyclic, and specific examples thereof include an alkyl group having 1 to 20 carbon atoms or a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom.

[0301] Examples of the repeating unit D6 include, but are not limited to, those shown below. In the following formula, R C is the same as above. [ka]

[0302] [ka]

[0303] [ka]

[0304] [ka]

[0305] The content of the repeating units D1 to D4 is preferably 15 to 95 mol %, more preferably 20 to 85 mol %, based on all repeating units of the fluorine atom-containing polymer. The content of the repeating units D5 and / or D6 is preferably 5 to 85 mol %, more preferably 15 to 80 mol %, based on all repeating units of the fluorine atom-containing polymer. The repeating units D1 to D6 may be used alone or in combination of two or more.

[0306] The fluorine atom-containing polymer may contain other repeating units in addition to the repeating units described above. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of JP2014-177407A. When the fluorine atom-containing polymer contains other repeating units, the content of such other repeating units is preferably 50 mol% or less of the total repeating units of the fluorine atom-containing polymer.

[0307] The fluorine-containing polymer can be synthesized by copolymerizing each monomer protected by a protecting group as necessary by a known method, and then carrying out a deprotection reaction as necessary. The copolymerization reaction is not particularly limited, but is preferably radical polymerization or anionic polymerization. For these methods, JP-A-2004-115630 can be referred to.

[0308] The Mw of the fluorine atom-containing polymer is preferably 2000 to 50000, more preferably 3000 to 20000. If the Mw is less than 2000, the diffusion of the acid is promoted, which may result in deterioration of the resolution and deterioration of the stability over time. If the Mw is too large, the solubility in the solvent may decrease, which may cause coating defects. Furthermore, the Mw / Mn of the fluorine atom-containing polymer is preferably 1.0 to 2.2, more preferably 1.0 to 1.7.

[0309] When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer (D), the content thereof 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, relative to 80 parts by mass of the base polymer (A). The fluorine atom-containing polymer (D) may be used alone or in combination of two or more kinds.

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

[0144] to

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

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

[0312] When the chemically amplified positive resist composition of the present invention contains an organic solvent (E), the content thereof is preferably 200 to 10,000 parts by mass, and more preferably 400 to 5,000 parts by mass, relative to 80 parts by mass of the base polymer (A). The organic solvent (E) may be used alone or in combination of two or more kinds.

[0313] [(F) Surfactant] The chemically amplified positive resist composition of the present invention may contain a surfactant commonly used as component (F) in order to improve the coating property to the substrate. Many of the surfactants are known, as described in JP-A-2004-115630, and the surfactant can be selected with reference to these. When the chemically amplified positive resist composition of the present invention contains the surfactant (F), the content is preferably 0 to 5 parts by mass relative to 80 parts by mass of the base polymer (A). The surfactant may be used alone or in combination of two or more types. When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer, the fluorine atom-containing polymer also serves as a surfactant, so the surfactant may not be contained.

[0314] The chemically amplified positive resist composition of the present invention can be prepared by dissolving components (A) to (C) and, if necessary, components (D) and (F) in an organic solvent of component (E) either simultaneously or in any order to prepare a homogeneous resist solution. The resist solution obtained is preferably filtered. By using nylon or polyethylene (PE) as a filter for filtration, gel components and particles contained in the resist solution can be effectively removed. Furthermore, in order to maintain quality for the latest generation, it is preferable to use a filter with a pore size of 20 nm or less.

[0315] In designing the chemically amplified positive resist composition of the present invention, the dissolution rate of the exposed portion of the resist film obtained in an alkaline developer is preferably 50 nm / sec or more from the viewpoint of improving development loading, and more preferably 80 nm / sec or more. By being 50 nm / sec or more, even if there is a difference in the pattern layout in the sparse and dense pattern, it is possible to uniformly dissolve in an alkaline developer, and the line width fluctuation can be reduced. The dissolution rate of the exposed portion in the present invention is a value calculated from the film loss amount when the chemically amplified positive resist composition of the present invention is spin-coated on an 8-inch silicon wafer, baked at 110°C for 60 seconds to form a resist film with a film thickness of 90 nm, exposed to KrF excimer laser light with an energy amount that completes the deprotection reaction of the polymer, 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.

[0316] In addition, the dissolution rate of the unexposed portion of the resist film obtained from the chemically amplified positive resist composition of the present invention in an alkaline developer is preferably 10 nm / min or less, more preferably 9 nm / min or less, and even more preferably 8 nm / min or less. When the resist film is in a thin film region (100 nm or less), the effect of the pattern film loss in the alkaline developer becomes large, and when the dissolution rate of the unexposed portion is greater than 10 nm / min, the pattern collapses and fine patterns cannot be formed. This is particularly noticeable in the production of photomasks that are required to be free of defects, since the development process tends to be strong. The dissolution rate of the unexposed portion is a value calculated from the film loss amount when the chemically amplified positive resist composition of the present invention is spin-coated on 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 with a 2.38 mass% TMAH aqueous solution at 23°C for 80 seconds.

[0317] [Method of forming resist pattern] The method for forming a resist pattern of the present invention includes the steps of forming a resist film on a substrate using the above-mentioned chemically amplified positive resist composition, irradiating the resist film with a pattern using EUV or EB, particularly EB (i.e., exposing the resist film with EUV or EB), and developing the resist film that has been irradiated with the pattern using an alkaline developer.

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

[0319] Next, the resist film is exposed to EUV or EB to irradiate a pattern. When EB is used, the EB energy is set to an exposure dose of 10 to 500 μC / cm to form a desired pattern. 2 , preferably 50 to 400 μC / cm 2 Irradiate so that

[0320] The exposure may be performed by a conventional exposure method, or in some cases by an immersion method in which the space between the mask and the resist film is immersed in liquid. In this case, a water-insoluble protective film may be used.

[0321] Next, post-exposure baking (PEB) is performed on a hot plate, preferably at 60 to 150° C. for 1 to 20 minutes, more preferably at 80 to 140° C. for 1 to 10 minutes.

[0322] Thereafter, the substrate is developed using a developer of an alkaline aqueous solution of 0.1 to 5 mass %, preferably 2 to 3 mass %, TMAH or the like, for preferably 0.1 to 3 minutes, more preferably 0.5 to 2 minutes, by a conventional method such as a dip method, a puddle method or a spray method, to form a desired pattern on the substrate.

[0323] The chemically amplified positive resist composition of the present invention is useful because it can form a pattern with particularly good resolution and small LER. Also, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on a substrate having a surface made of a material that is prone to pattern peeling or pattern collapse because it is difficult to obtain adhesion of the resist pattern. Examples of such substrates include substrates having a sputtering film formed on the outermost surface of a chromium compound containing one or more light elements selected from metallic chromium, oxygen, nitrogen, and carbon, SiO, SiO x , a tantalum compound, a molybdenum compound, a cobalt compound, a nickel compound, a tungsten compound, or a tin compound in the outermost layer. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation using a photomask blank as the substrate. In this case, the photomask blank may be either a transmission type or a reflection type.

[0324] As a transmission type mask blank, a photomask blank having a light-shielding film made of a chromium-based material may be a photomask blank for a binary mask or a photomask blank for a phase shift mask. In the case of a photomask blank for a binary mask, the light-shielding film may have an antireflection layer and a light-shielding layer made of a chromium-based material, and the entire antireflection film on the surface layer side or only the surface layer side of the antireflection film on the surface layer side may be made of a chromium-based material, and the remaining part may be made of a silicon-based compound material that may contain a transition metal, for example. In the case of a photomask blank for a phase shift mask, a photomask blank for a phase shift mask having a chromium-based light-shielding film on a phase shift film may be the target.

[0325] The above-mentioned photomask blank having a chromium-based material in the outermost layer is very well known, as exemplified in JP2008-26500A and JP2007-302873A or as prior art therein, and detailed description will be omitted. For example, when forming a light-shielding film having an antireflection layer and a light-shielding layer using a chromium-based material, the following film configuration can be used.

[0326] When a light-shielding film having an anti-reflection layer and a light-shielding layer is formed using a chromium-based material, the layer structure may be such that the anti-reflection layer and the light-shielding layer are laminated in this order from the surface layer side, or the anti-reflection layer, the light-shielding layer, and the anti-reflection layer are laminated in this order. The anti-reflection layer and the light-shielding layer may each be multi-layered, and the composition between layers having different compositions may change discontinuously or may change continuously. As the chromium-based material to be used, a material containing light elements such as oxygen, nitrogen, and carbon in metal chromium is used. Specifically, metal chromium, chromium oxide, chromium nitride, chromium carbide, chromium oxide nitride, chromium carbide oxide, chromium nitride, chromium oxynitride, etc. may be used.

[0327] The reflective mask blank includes a substrate, a multilayer reflective film formed on one main surface (front surface) of the substrate, specifically, a multilayer reflective film that reflects exposure light such as EUV light, and an absorber film formed on the multilayer reflective film, specifically, an absorber film that absorbs exposure light such as EUV light and reduces reflectance. From the reflective mask blank (EUV reflective mask blank), a reflective mask (EUV reflective mask) having an absorber pattern (absorber film pattern) formed by patterning the absorber film is manufactured. The wavelength of EUV light used in EUV lithography is 13 to 14 nm, and is usually light with a wavelength of about 13.5 nm.

[0328] The multilayer reflective film is usually preferably provided in contact with one main surface of the substrate, but it is also possible to provide an undercoat film between the substrate and the multilayer reflective film, provided that the effect of the present invention is not lost. The absorber film may be formed in contact with the multilayer reflective film, but a protective film (protective film for the multilayer reflective film) may be provided between the multilayer reflective film and the absorber film, preferably in contact with the multilayer reflective film, more preferably in contact with the multilayer reflective film and the absorber film. The protective film is used to protect the multilayer reflective film during processing such as cleaning and correction. In addition, the protective film is preferably one that has the function of protecting the multilayer reflective film when the absorber film is patterned by etching, and preventing the oxidation of the multilayer reflective film. On the other hand, a conductive film used for electrostatic chucking the reflective mask to the exposure device may be provided under the other main surface (back surface) that is the surface opposite to the one main surface of the substrate, preferably in contact with the other main surface. In this embodiment, one main surface of the substrate is the front surface and the upper side, and the other main surface is the back surface and the lower side, but the front and back and the top and bottom of both are defined for convenience, and the one main surface and the other main surface are either of the two main surfaces (film formation surfaces) of the substrate, and the front and back and the top and bottom are interchangeable. More specifically, it can be formed by a method such as that exemplified in JP 2021-139970 A or the prior art therein.

[0329] According to the method for forming a resist pattern of the present invention, even when a substrate (e.g., a transmissive or reflective mask blank) is used whose outermost surface is made of a material that is likely to affect the resist pattern shape, such as a material containing chromium, silicon or tantalum, it is possible to obtain a high-resolution pattern with small dimensional difference that is independent of pattern density and in which the effects of development loading and residue defects are suppressed. EXAMPLES

[0330] 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 a molar ratio, and Mw is a weight average molecular weight in terms of polystyrene measured by GPC.

[0331] [1] Polymer synthesis [Synthesis Example] Synthesis of Polymer P-1 In a 200 mL flask, 20 g of polyhydroxystyrene-acenaphthylene copolymer and 180 g of THF as a solvent were added. After adding 12 g of triethylamine to this reaction solution at about 25° C. under a nitrogen atmosphere, 19 g of an acetalizing agent Ac-1 represented by the following formula was dripped in over 30 minutes and reacted at room temperature for 3 hours. After the reaction was completed, 12 g of acetic acid was added, the resulting reaction solution was dripped into 500 g of hexane, and the precipitated copolymer was filtered off. The filtered copolymer was washed twice with 120 g of hexane. The resulting copolymer was dissolved in a mixed solvent of 60 g of ethyl acetate and 20 g of water, and the resulting solution was transferred to a separatory funnel and subjected to a water washing and separation operation. The organic layer after separation was concentrated and then dissolved in 40 g of acetone, and the resulting solution was dripped into 600 g of water, and the resulting crystallized precipitate was filtered off, washed with water, and dried to obtain 20.8 g of the target polymer P-1, which is a white polymer. Polymer P-1 was 13 C-NMR, 1 Measurement by H-NMR and GPC gave the following analytical results: [ka] [ka]

[0332] In addition, polymers P-2 to P-19 and comparative polymers cP-1 to cP-5 and AP-1 to AP-5 shown below were synthesized in the same manner as in the above synthesis examples or known methods, except that the types and compounding ratios of each monomer were changed.

[0333] [ka]

[0334] [ka]

[0335] [ka]

[0336] [ka]

[0337] [ka]

[0338] [ka]

[0339] [ka]

[0340] The dissolution rate of the polymer in an alkaline developer was calculated by spin-coating a polymer solution (polymer concentration: 16.7% by mass, solvent: PGMEA) on an 8-inch silicon wafer, baking at 100°C for 90 seconds to form a film with a thickness of 1000 nm, developing with a 2.38% by mass aqueous TMAH solution at 23°C for 100 seconds, and measuring the amount of film loss. As a result, the dissolution rates of P-1 to P-19, AP-1 to AP-5, and cP-1 to cP-4 were 5 nm / min or less, and the dissolution rate of cP-5 was 14 nm / min.

[0341] [2] Preparation of chemically amplified positive resist composition [Examples 1-1 to 1-41, Comparative Examples 1-1 to 1-5] Chemically amplified positive resist compositions were prepared by dissolving each component in an organic solvent according to the compositions shown in Tables 1 to 3 below, and filtering the resulting solution through a 5 nm nylon filter and a 1 nm UPE filter. The organic solvent was a mixed solvent of 940 parts by mass of PGMEA, 1870 parts by mass of EL, and 1870 parts by mass of PGME.

[0342] The dissolution rate of the resist composition in an alkaline developer was calculated by spin-coating the resist composition on an 8-inch silicon wafer, baking the resist film at 110° C. for 240 seconds to form a resist film with a thickness of 80 nm, developing the resist film in a 2.38 mass % TMAH aqueous solution at 23° C. for 80 seconds, and measuring the amount of film loss. As a result, the dissolution rates of the resist films obtained from resist compositions R-1 to R-41 and CR-1 to CR-5 were 10 nm / min or less, and the dissolution rate of the resist film obtained from resist composition CR-6 was 16 nm / min.

[0343] [Table 1]

[0344] [Table 2]

[0345] [Table 3]

[0346] In Tables 1 to 3, the structures of the photoacid generators PAG-1 to PAG-6, the quenchers Q-1 to Q-4 and the fluorine atom-containing polymers FP-1 to FP-5 are as follows. [ka]

[0347] [ka]

[0348] [ka]

[0349] [3] EB lithography evaluation [Examples 2-1 to 2-41, Comparative Examples 2-1 to 2-5] Each chemically amplified positive resist composition (R-1 to R-41, CR-1 to CR-5) was spin-coated using ACT-M (Tokyo Electron Ltd.) onto a reflective mask blank for EUV exposure masks, which was a 6-inch-side low-thermal expansion glass substrate with a 284-nm-thick Mo / Si 40-layer multilayer reflective film, a 3.5-nm-thick Ru film as a protective film, a 70-nm-thick TaN film as an absorbing layer, and a 6-nm-thick CrN film as a hard mask. The mask blank was prebaked 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 film was measured using an optical measuring instrument Nanospec (Nanometrics). Measurements were performed at 81 points on the surface of the blank substrate, excluding the outer edge portion from the outer periphery to the inside of 10 mm, and the average thickness and thickness range were calculated. Furthermore, the resist film was exposed using an EB exposure device (EBM-5000plus, manufactured by NuFlare Technology, Inc., acceleration voltage 50 kV), subjected to PEB at 110° C. for 600 seconds, and developed with a 2.38 mass % TMAH aqueous solution to obtain a positive pattern. The obtained resist patterns were evaluated as follows. The prepared patterned mask blanks were observed with an overhead SEM (scanning electron microscope), and the exposure dose required to resolve 200 nm 1:1 line and space (LS) at 1:1 was determined as the optimal exposure dose (μC / cm 2 ) and the minimum dimension at the exposure dose that resolves at 1:1 was taken as the resolution (limiting LS resolution), and the LER of 200 nm LS was measured by SEM. The pattern shape was visually judged to be rectangular or not. The results are shown in Tables 4 to 6.

[0350] [Table 4]

[0351] [Table 5]

[0352] [Table 6]

[0353] [4] Residual defect evaluation [Examples 3-1 to 3-8, Comparative Examples 3-1 to 3-2] The resist compositions (R-8, R-15 to R-20, R-33, CR-3, CR-4) were applied to a reflective mask blank for EUV exposure mask in the same manner as above to form a resist film with a thickness of 80 nm, and the resist film was fully exposed to light at the optimal exposure dose for each resist composition using an EB exposure device (EBM-5000plus, manufactured by NuFlare Technology, Inc., acceleration voltage 50 kV), and PEB was applied for 600 seconds at 110 ° C., development was performed with a 2.38 mass % TMAH aqueous solution, and development residue was evaluated using a mask defect inspection device (M9650, manufactured by Lasertec Corporation). The total number of defects after development is shown in Table 7.

[0354] [Table 7]

[0355] The chemically amplified positive resist compositions (R-1 to R-41) of the present invention all exhibited good LS resolution, LER, and pattern rectangularity, and showed values ​​that suppressed development loading. On the other hand, the resist compositions of the comparative examples (CR-1 to CR-5) had insufficient design of the base polymer in CR-1 to CR-4, and the performance was insufficient in terms of line and space resolution, LER, and pattern rectangularity. In CR-5, the dissolution rate of the unexposed part of the polymer was high, resulting in a round head shape and deteriorating resolution. In addition, in the residue defect evaluation, the performance was insufficient in CR-3 and CR-4. It is considered that the resist composition using the base polymer with a specific acetal type acid labile group and a limited number of halogen atoms as the design of the present invention has realized a pattern that exhibits good resolution, pattern shape, and LER, even in the high dose region, and suppresses the effect of residue defects on the alkaline developer.

[0356] The method of forming a resist pattern using the chemically amplified positive resist composition of the present invention is useful for the production of semiconductor devices, particularly for photolithography in the processing of transmission and reflection photomask blanks.

Claims

1. A chemically amplified positive resist composition comprising: (A) a base polymer; (B) a photoacid generator; and (C) a quencher, (A) the base polymer comprises a polymer containing a phenolic hydroxy group-containing unit represented by the following formula (A1), an aromatic ring-containing unit represented by any one of the following formulae (A2) to (A4), and a phenolic hydroxy group-containing unit protected by an acid labile group represented by formula (A5), (A) all of the repeating units contained in the base polymer have an aromatic ring; (A) The number of halogen atoms contained in the repeating unit constituting the base polymer is 3 or less. A chemically amplified positive resist composition. 【Chemistry 1】 (In the formula, a1 is an integer satisfying 0≦a1≦5+2(a3)−a2. a2 is an integer from 1 to 3. a3 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 in the main chain. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 A part of - 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. 【Chemistry 2】 (In the formula, b and c are each independently an integer of 0 to 4. d1 is an integer of 0 to 5. d2 is an integer of 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 A part of - may be substituted with -O-. R 2 and R 3 each independently represents a hydroxy group, a halogen atom, a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyl group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbyloxy group having 1 to 8 carbon atoms which may be substituted with a halogen atom. R 4 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 may be a hydroxy group when d2 is 1 or 2. 【Chemistry 3】 [In the formula, e1 is an integer satisfying 0≦e1≦5+2(e3)−e2, e2 is an integer from 1 to 3, and e3 is an integer from 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 A part of - may be substituted with -O-. R 5 represents 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 AL is an acetal type acid labile group represented by the following formula (AL-1) when e2 is 1, and is a hydrogen atom or an acetal type acid labile group represented by the following formula (AL-1) when e2 is 2 or more, provided that at least one of them is an acetal type acid labile group represented by the following formula (AL-1). 【Chemistry 4】 (In the formula, f1 is an integer from 0 to 2. f2 is an integer satisfying 0≦f2≦5+2(f1). R 6 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. R L1 is a hydrocarbyl group having 1 to 30 carbon atoms. The dashed lines represent bonds.)

2. 2. The chemically amplified positive resist composition according to claim 1, wherein the phenolic hydroxy group-containing unit is a repeating unit represented by the following formula (A1-1): 【Chemistry 5】 (In the formula, R A and a2 are the same as above.

3. 2. The chemically amplified positive resist composition according to claim 1, wherein the unit containing a phenolic hydroxy group protected by an acid labile group is a repeating unit represented by the following formula (A5-1): 【Chemistry 6】 (In the formula, R A , R 6 , f1, f2 and R L1 is the same as above.)

4. 2. The chemically amplified positive resist composition according to claim 1, wherein the acid strength (pKa) of the acid generated by the photoacid generator (B) is -3.0 or more.

5. 2. The chemically amplified positive resist composition according to claim 1, wherein the content ratio of the photoacid generator (B) to the quencher (C), ((B) / (C)), is less than 3 in terms of mass ratio.

6. 2. The chemically amplified positive resist composition according to claim 1, wherein the photoacid generator (B) is an onium salt compound containing an anion represented by the following formula (B-1) or (B-2): 【Chemistry 7】 (In the formula, m1 and m2 each independently represent an integer of 0 to 2. m3 represents an integer of 1 to 5 when m1=0, an integer of 1 to 7 when m1=1, and an integer of 1 to 9 when m1=2. m4 represents an integer of 0 to 5 when m2=0, an integer of 0 to 7 when m2=1, and an integer of 0 to 9 when m2=2. L 1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, an amide bond, a carbonate bond or a carbamate bond. R 11 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 11 L 1 is bonded to a carbon atom adjacent to the carbon atom to which m3 is bonded. 11 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 12 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 12 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 is a carbon atom C of an adjacent aromatic ring. 1 and C 2 and a part of the carbon atoms forming the ring may be substituted with a group containing a hetero atom. W 2 is a carbon atom C of an adjacent aromatic ring. 3 and C 4 A ring having 3 to 15 carbon atoms formed together with 【Chemistry 8】 (In the formula, n1 and n2 are each independently an integer of 0 to 2. n3 is an integer of 1 to 4 when n2=0, an integer of 1 to 6 when n2=1, and an integer of 1 to 8 when n2=2. n4 is an integer of 0 to 3 when n2=0, an integer of 0 to 5 when n2=1, and an integer of 0 to 7 when n2=2. However, n3+n4 is an integer of 1 to 4 when n2=0, an integer of 1 to 6 when n2=1, and an integer of 1 to 8 when n2=2. n5 is an integer of 1 to 5 when n1=0, an integer of 1 to 7 when n1=1, and an integer of 1 to 9 when n1=2. R 21 are each independently an iodine atom or a branched or cyclic hydrocarbyl group having 3 to 20 carbon atoms which may contain a heteroatom, and at least one R 21 L 11 is bonded to a carbon atom adjacent to the carbon atom to which n5 is bonded. 21 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 22 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom, and when n4 is 2 or more, 22 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R F1 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 6 carbon atoms, a fluorinated alkoxy group having 1 to 6 carbon atoms, or a fluorinated thioalkoxy group having 1 to 6 carbon atoms. L 11 and L 12 is a single bond, an ether bond, an ester bond, an amide bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. X L is a single bond or a hydrocarbylene group having 1 to 40 carbon atoms which may contain a heteroatom.

7. 7. The chemically amplified positive resist composition according to claim 6, wherein the photoacid generator (B) is an onium salt compound having no fluorine atom in the anion.

8. The chemically amplified positive resist composition according to claim 1, further comprising (D) a fluorine atom-containing polymer which contains at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D1), a repeating unit represented by the following formula (D2), a repeating unit represented by the following formula (D3), and a repeating unit represented by the following formula (D4), and which may further contain at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (D5) and a repeating unit represented by the following formula (D6): 【Chemistry 9】 (In the formula, x is 1, 2, or 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. k is 1, 2, or 3. R B each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R C are each independently a hydrogen atom or a methyl group. R 101 , R 102 , R 104 and R 105 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 103 , R 106 , R 107 and R 108 are each independently a hydrogen atom, a hydrocarbyl group having 1 to 15 carbon atoms, a fluorinated hydrocarbyl group having 1 to 15 carbon atoms, or an acid labile group; 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 present between the carbon-carbon bonds. R 109 is a hydrogen atom or a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group interposed between the carbon-carbon bonds. R 110 is a linear or branched hydrocarbyl group having 1 to 5 carbon atoms which may have a heteroatom-containing group between its carbon-carbon bonds. R 111 is a saturated hydrocarbyl group having 1 to 20 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, and the —CH 2 A part of the - may be substituted with an ester bond or an ether bond. Z 1 is a (k+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (k+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or -C(=O)-NH-Z 31 -Z 32 - is. 31 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms. 32 is a single bond, an ester bond, an ether bond or a sulfonamide bond. * indicates a bond to a carbon atom in the main chain.)

9. 2. The chemically amplified positive resist composition according to claim 1, further comprising (E) an organic solvent.

10. 2. The chemically amplified positive resist composition according to claim 1, wherein the dissolution rate of said base polymer in an alkaline developer is 5 nm / min or less.

11. 2. The chemically amplified positive resist composition according to claim 1, wherein a dissolution rate of unexposed areas of a resist film obtained from said chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less.

12. 2. The chemically amplified positive resist composition according to claim 1, which is used for electron beam lithography.

13. A method for forming a resist pattern, comprising the steps of: forming a resist film on a substrate using the chemically amplified positive resist composition according to any one of claims 1 to 12; irradiating the resist film with an extreme ultraviolet ray or an electron beam to form a pattern; and developing the resist film irradiated with the pattern using an alkaline developer.

14. 14. The method for forming a resist pattern according to claim 13, wherein the outermost surface of the substrate is made of a material containing at least one element selected from the group consisting of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin.

15. 14. The method of forming a resist pattern according to claim 13, wherein the substrate is a transmission type or a reflection type mask blank.

16. A transmission or reflection mask blank coated with the chemically amplified positive resist composition according to any one of claims 1 to 12.

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