Acetal modifier, polymer, chemically amplified positive resist composition and method for forming resist pattern

Abstract

To provide a chemically amplified positive resist composition having very high isolated space resolution, small LER, and excellent rectangularity, capable of suppressing effects of development loading and residual defects, in addition capable of imparting a resist film capable of forming a resist pattern with suppressed etching resistance and pattern collapse, an acetal modifier for producing a base polymer used in the resist composition, a polymer modified with the acetal modifier, and a method for forming a resist pattern using the chemically amplified positive resist composition.SOLUTION: The present invention provides: an acetal modifier having a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom, which serves as a protecting group for an aliphatic or aromatic hydroxy group; a polymer which contains a repeating unit A1 having, at its side chain, a structure in which an aromatic hydroxy group is protected with an acid labile group represented by the following formula (AL-1) or (AL-2), and which becomes alkali-soluble upon being deprotected by the action of an acid; and a chemically amplified positive resist composition comprising a base polymer which contains the polymer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an acetal modifying agent, a polymer, 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 describe examples in which the acid diffusion is suppressed and LER is reduced by increasing the bulkiness of the acid generated from an acid generator. However, these acid generators are still insufficient in suppressing acid diffusion, and therefore, there has been a demand for the development of an acid generator with smaller acid diffusion.

[0006] Patent Document 3 describes an example of controlling acid diffusion by introducing a repeating unit having a sulfonium structure that generates sulfonic acid upon exposure into a polymer used in a resist composition. The method of suppressing acid diffusion by introducing 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 resist film region of 100 nm or less in thickness and in a high dose region where irradiation energy is high. Therefore, if the reactivity and structure of the acetal are bulky, a deprotection reaction will occur even in unexposed areas of the resist film, and residues will remain even in exposed areas, resulting in problems such as deterioration of isolated space resolution and LER, which are particularly important in positive resist compositions, and the occurrence of defects.

[0010] It is known that in the development process of photomask manufacturing, a phenomenon called development loading occurs, in which the dimensional finish of the pattern differs between dense and sparse areas on the photomask. That is, development loading causes uneven distribution of the dimensional finish of the pattern depending on the surrounding pattern distribution. The causes include differences in the desorption reaction during acid generation due to the energy difference of EB, and differences in the dissolution rate in the alkaline developer of the sparse and dense pattern drawing part. As one of the improvements, Patent Document 9 discloses a method of adjusting the incident dose in an EB drawing device to correct the development loading, irradiating EB, and drawing a pattern on a photomask. However, the conventional correction method does not sufficiently take the development loading into consideration for correction. For this reason, the conventional correction method did not have good correction accuracy for the development loading. To solve this problem, methods have been developed to improve the writing methods for writing resist films and the development methods after patterning, as described in Patent Documents 10 and 11. However, these methods are insufficient for uniformly distributing sparse and dense fine patterns in the advanced generation, and there has been a demand for improved resist compositions that can achieve high resolution, reduced development loading, and reduced residue defects even in the advanced 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. 39811830 [Patent Document 5] Patent No. 5385017 [Patent Document 6] International Publication No. 2019 / 167419 [Patent Document 7] Patent No. 6987873 [Patent Document 8] Patent No. 5696254 [Patent Document 9] JP 2007-150243 A [Patent Document 10] Patent No. 5443548 [Patent Document 11] Patent No. 6281244 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 providing a resist film that has extremely high isolated space resolution, small LER, excellent rectangularity, and suppresses the effects of development loading and residue defects, as well as enabling the formation of a resist pattern that has excellent etching resistance and suppressed pattern collapse; an acetal modifier for producing a base polymer used in the resist composition; a polymer modified with the acetal modifier; and a method of forming a resist pattern that uses the chemically amplified positive resist composition. [Means for solving the problem]

[0013] Means for Solving the Problems The present inventors have conducted intensive research in order to achieve the above-mentioned object, and as a result have found that by using a resist composition containing a base polymer having an acid labile group derived from an acetal modifier having a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom, it is possible to obtain a pattern that exhibits good isolated space resolution, pattern shape, and LER, even in a high dose region, and that suppresses the effects of development loading and residue defects, thereby completing the present invention.

[0014] That is, the present invention provides the following acetal modifying agent, polymer, chemically amplified positive resist composition, and method of forming a resist pattern. 1. Acetal modifying agents which give groups having cyclic saturated heterocycles containing oxygen or sulfur atoms which serve as protecting groups for aliphatic or aromatic hydroxy groups. 2. Acetal modification of 1 to provide a group that serves as a protecting group for aromatic hydroxy groups. 3. An acetal modifying agent according to the formula 1 or 2, which is a compound represented by the following formula (AC-1) or (AC-2): [ka] (In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 15 carbon atoms. L1 and R L2 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached, R L5 ~R L7 Any two of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L3 and R L4 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached, R L8 and RL9 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 are each independently a group containing a saturated heterocyclic ring containing an oxygen atom or a sulfur atom. X is a chlorine atom, a bromine atom or an iodine atom. m1 and m2 each independently represent an integer of 0 to 3. 4. A polymer comprising a repeating unit A1 having, in its side chain, a structure in which an aromatic hydroxy group is protected with an acid labile group represented by the following formula (AL-1) or (AL-2), and which becomes alkali-soluble upon being deprotected by the action of an acid. [ka] (In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 15 carbon atoms. L1 and R L2 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached, R L5 ~R L7 Any two of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L3 and R L4 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached, R L8 and R L9 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 are each independently a group containing a saturated heterocyclic ring containing an oxygen atom or a sulfur atom. m1 and m2 each independently represent an integer of 0 to 3. The dashed line represents a bond to the oxygen atom of the aromatic hydroxy group. 5. The polymer of 4, wherein the repeating unit A1 is represented by the following formula (A1): [ka] (In the formula, a1 is 0 or 1. When a1=0, a2 is an integer of 0 to 4, and when a1=1, a2 is an integer of 0 to 6. A3 is an integer of 1 to 3, with the proviso that when a1=0, 1≦a2+a3≦5, and when a1=1, 1≦a2+a3≦7. 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. X 2 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2 A portion of - may be replaced by -O-. R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. R is an acid labile group represented by formula (AL-1) or (AL-2). 6. The polymer of 4 or 5 further comprising a phenolic hydroxy group-containing repeating unit A2 represented by the following formula (A2): [ka] (In the formula, b1 is 0 or 1. When b1=0, b2 is an integer of 0 to 4, and when b1=1, b2 is an integer of 0 to 6. When b1=0, b2+b3 is an integer of 1 to 3, with the proviso that 1≦b2+b3≦5 and when b1=1, 1≦b2+b3≦7. R Ais 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. X 4 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2 A portion of - may be replaced by -O-. R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. 7. The polymer according to 6, wherein the repeating unit A2 is represented by the following formula (A2-1): [ka] (In the formula, R A and b3 are the same as above.) 8. The polymer according to any one of 4 to 7, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (A3-1) and a repeating unit represented by the following formula (A3-2): [ka] (In the formula, c1 is 0 or 1. c2 is an integer of 0 to 2. c3 is an integer satisfying 0≦c3≦5+2(c2)−c4. c4 is an integer of 1 to 3. c5 is 0 or 1. d1 is an integer from 0 to 2. d2 is an integer from 0 to 2. d3 is an integer from 0 to 5. d4 is an integer from 0 to 2. R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2- may be replaced by -O-. A 4 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OA 41 -It is. 41 is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * is a bond to a carbon atom of the main chain. R 3 represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. R 4 and R 5 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, R 4 and R 5 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 6 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 7 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. X A is an acid labile group when c4 is 1, and is a hydrogen atom or an acid labile group when c4 is 2 or 3, but at least one is an acid labile group. 9. A polymer according to any one of 4 to 8, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B1), a repeating unit represented by the following formula (B2), and a repeating unit represented by the following formula (B3): [ka] (In the formula, e and f each independently represent an integer of 0 to 4; g1 represents an integer of 0 to 5; and g2 represents an integer of 0 to 2.) R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 5 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 5 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2 A portion of - may be replaced by -O-. R 11 and R 12 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 13 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 when g2 is 1 or 2, it may also be a hydroxy group. 10. A polymer according to any one of 4 to 9, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (C1), a repeating unit represented by the following formula (C2), a repeating unit represented by the following formula (C3), and a repeating unit represented by the following formula (C4): [ka] (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 is a single bond or a phenylene group. Z 2 teeth,* 1 -C(=O)-OZ 21 -, * 1-C(=O)-NH-Z 21 -or* 1 -OZ 21 -It is. 21 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group.* 1 is Z 1 Represents a bond with . Z 3 each independently represents a single bond, a phenylene group, a naphthylene group, or * 2 -C(=O)-OZ 31 -It is. 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 2 represents a bond to a carbon atom in the main chain. Z 4 each independently represents a single bond, * 3 -Z 41 -C(=O)-O-, * 3 -C(=O)-NH-Z 41 -or* 3 -OZ 41 -It is. It is. Z 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 3 is Z 3 Represents a bond with . Z 5 each independently represents a single bond, * 4 -Z 51 -C(=O)-O-, * 4 -C(=O)-NH-Z 51 -or* 4 -OZ 51 -It is. 51 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 4 is Z 4 Represents a bond with . Z 6is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, * 2 -C(=O)-OZ 61 -, * 2 -C(=O)-N(H)-Z 61 -or* 2 -OZ 61 -It is. 61 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group. 2 represents a bond to a carbon atom in the main chain. * indicates a bond to a carbon atom in the main chain. R 31 and R 32 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 31 and R 32 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. k1 and k2 each independently represent an integer of 0 to 3. 11. A chemically amplified positive resist composition comprising a base polymer comprising any one of the polymers recited in 4 to 10. 12. A chemically amplified positive resist composition according to claim 11, further comprising an organic solvent. 13. The chemically amplified positive resist composition according to 11 or 12, further comprising a photoacid generator that generates an acid having an acid strength (pKa) of -2.0 or more. 14. The chemically amplified positive resist composition according to any one of 11 to 13, wherein the photoacid generator contains an anion represented by the following formula (P1): [ka] (In the formula, m1 is 0 or 1. p is an integer of 1 to 3. q is an integer of 1 to 5. r is an integer of 0 to 3. L 1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. L 2 is an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. L A represents 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. Rf 1 and Rf 2 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group. R 101is 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 101A )(R 101B ), -N(R 101C )-C(=O)-R 101D Or -N(R 101C )-C(=O)-OR 101D R 101A and R 101B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 101C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 101D is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 102 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. 15. The chemically amplified positive resist composition according to any one of 11 to 14, further comprising a quencher. 16. The chemically amplified positive resist composition according to any one of 11 to 15, further comprising a fluorine atom-containing polymer containing 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). [ka] (In the formula, R B each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 301 , R 302 , R304 and R 305 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 303 , R 306 , R 307 and R 308 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 203 , R 206 , R 207 and R 208 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. n is an integer from 1 to 3. Z 1 is a (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms. 17. The chemically amplified positive resist composition of 16, wherein the fluorine atom-containing polymer further contains 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): [ka] (In the formula, R C are each independently a hydrogen atom or a methyl group. R 309 represents 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 310 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 311 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 portion of - may be substituted with an ester bond or an ether bond. x is an integer of 1 to 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-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.) 18. The chemically amplified positive resist composition according to any one of 11 to 17, wherein the dissolution rate of the polymer in an alkaline developer is 10 nm / min or less. 19. The chemically amplified positive resist composition according to any one of 11 to 18, wherein the dissolution rate of unexposed areas of a resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 10 nm / min or less. 20. The chemically amplified positive resist composition of any one of 11 to 19, wherein the dissolution rate of the exposed area of ​​a resist film obtained from the chemically amplified positive resist composition in an alkaline developer is 50 nm / sec or higher. 21. 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 11 to 20; irradiating the resist film with a pattern using high-energy rays; and developing the resist film irradiated with the pattern using an alkaline developer. 22. The method for forming a resist pattern according to claim 21, wherein the high-energy radiation is KrF excimer laser light, ArF excimer laser light, EB or EUV having a wavelength of 3 to 15 nm. 23. The method for forming a resist pattern according to 21 or 22, wherein the outermost surface of the substrate is made of a material containing at least one selected from the group consisting of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin. 24. The chemically amplified positive resist composition according to any one of 21 to 23, wherein the substrate is a transmission type or a reflection type mask blank. 25. A transmission or reflection mask blank coated with any one of the chemically amplified positive resist compositions of 11 to 20. Effect of the Invention

[0015] The chemically amplified positive resist composition containing the polymer modified with the acetal modifier of the present invention is capable of forming a pattern with high resolution, small LER, and excellent rectangularity with a good shape after exposure, as well as a pattern with suppressed effects of residual defects, and is suitable as a resist composition for forming an EB-sensitive resist film used in processing semiconductors, photomask blanks, etc. Furthermore, the 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 with suppressed effects of residual defects, and is therefore suitable for use in microfabrication techniques, particularly 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] [Acetal modifier] The acetal modifying agent of the present invention provides a group having a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom that serves as a protecting group for an aliphatic or aromatic hydroxy group.

[0018] The acetal modifying agent is preferably one represented by the following formula (AC-1) or (AC-2). [ka]

[0019] In formulas (AC-1) and (AC-2), R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 15 carbon atoms. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 15 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, or a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 15 carbon atoms, such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, or a cyclopropylmethyl group; alkenyl groups having 2 to 15 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, or a hexenyl group; and cyclic unsaturated hydrocarbyl groups having 3 to 15 carbon atoms, such as a cyclohexenyl group, but are not limited thereto.

[0020] Also, R L1 and R L2 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached, R L5 ~R L7 Any two of may be bonded to each other to form a ring together with the carbon atom to which they are bonded. Specific examples of the ring include, but are not limited to, a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a norbornane ring, an adamantane ring, and the like.

[0021] R L1 , R L2 , R L5 , R L6 and R L7 is appropriately selected depending on the design of the sensitivity of the decomposable group to acid. For example, if the design is to ensure relatively high stability and be decomposed by strong acid, a hydrogen atom is selected, and if the design is to use relatively high reactivity to increase sensitivity to pH changes and suppress residual defects, a linear alkyl group is selected. L1 , R L2 , R L5 , RL6 and R L7 Specific examples of the group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a cyclopentyl group, a cyclohexyl group, and a t-butyl group. Of these, a methyl group is preferred in terms of having optimal acid elimination performance.

[0022] In the acetal modifying agent represented by formula (AC-2), R L5 , R L6 and R L7 It is preferable that the carbon atom to which is bonded is a secondary carbon atom, particularly from the viewpoint of the stability of the polymer and the reactivity with an acid.

[0023] In formulas (AC-1) and (AC-2), R L3 , R L4 , R L8 and R L9 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R L1 , R L2 , R L5 , R L6 and R L7 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0024] Also, R L3 and R L4 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached, R L8 and R L9 and may be bonded to each other to form a ring together with the carbon atom to which they are attached. Specific examples of the ring include R L1 and R L2 and , when bonded to each other, can form a ring together with the carbon atom to which they are bonded, similar to the rings exemplified above.

[0025] In formulas (AC-1) and (AC-2), W 1is a group containing a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom. The cyclic saturated heterocycle is preferably a cyclic ether, a cyclic sulfide, a cyclic sulfoxide, a cyclic sulfone, etc., and more preferably a cyclic ether, a cyclic sulfide, etc. In addition, a lactone structure or a sulfone structure is not preferred because it has too high an acid diffusion suppressing ability and thus significantly reduces the sensitivity of the resist film.

[0026] W 1 Specific examples of the structure of the group containing a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom represented by the following formula (1) include, but are not limited to, those shown below. [ka]

[0027] In formula (AC-2), X is a chlorine atom, a bromine atom, or an iodine atom. From the viewpoint of synthesis, X is preferably a chlorine atom.

[0028] In formulae (AC-1) and (AC-2), m1 and m2 each independently represent an integer of 0 to 3. From the viewpoint of ease of progression of the modification reaction of the base polymer described below, m1 and m2 are preferably 1 or 2, and more preferably 1.

[0029] Specific examples of the acetal modifying agent represented by formula (AC-1) include, but are not limited to, those shown below. [ka]

[0030] [ka]

[0031] [ka]

[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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[0038]

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[0039]

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[0040]

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[0046]

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[0050]

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[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] [ka]

[0080] [ka]

[0081] Specific examples of the acetal modifying agent represented by formula (AC-2) include, but are not limited to, those shown below. [ka]

[0082] [ka]

[0083] [ka]

[0084] [ka]

[0085]

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[0086]

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[0087]

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[0088]

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[0090]

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[0138] [ka]

[0139] [ka]

[0140] [ka]

[0141] [ka]

[0142] [ka]

[0143] [ka]

[0144] [ka]

[0145] [polymer] The polymer of the present invention contains a repeating unit A1 having, in its side chain, a structure in which an aromatic hydroxy group is protected with an acid labile group represented by the following formula (AL-1) or (AL-2), and becomes alkali-soluble upon being deprotected by the action of an acid. [ka] (In the formula, R L1 ~R L9 , W 1 , m1 and m2 are the same as above. The dashed lines represent bonds to the oxygen atom of the aromatic hydroxy group.

[0146] The repeating unit A1 is preferably one represented by the following formula (A1). [ka]

[0147] In formula (A1), a1 is 0 or 1. When a1=0, a2 is an integer from 0 to 4, and when a1=1, a2 is an integer from 0 to 6. A3 is an integer from 1 to 3, with the proviso that when a1=0, 1≦a2+a3≦5, and when a1=1, 1≦a2+a3≦7.

[0148] In formula (A1), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0149] 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.

[0150] In formula (A1), X 2 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Among these, a single bond, an ether bond or an ester bond is preferred, and a single bond or an ester bond is more preferred.

[0151] In formula (A1), A 1 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2A part of - 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 methanediyl group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, and structural isomers thereof; cyclic saturated hydrocarbylene groups having 3 to 10 carbon atoms, such as cyclopropanediyl group, cyclobutanediyl group, cyclopentanediyl group, and cyclohexanediyl group; and groups obtained by combining these.

[0152] In formula (A1), R 1 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The saturated 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, and tert-butyl groups; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl groups; aryl groups having 2 to 20 carbon atoms, such as phenyl and naphthyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these groups. Of these, aryl groups are preferred. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine 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, or the like.

[0153] In formula (A1), R is an acid labile group represented by formula (AL-1) or (AL-2).

[0154] Specific examples of the repeating unit A1 include, but are not limited to, those shown below: In the following formula, R is the same as defined above. [ka]

[0155] [ka]

[0156] [ka]

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] [ka]

[0161] [ka]

[0162] [ka]

[0163] The content of the repeating unit A1 in all repeating units of the polymer is preferably from 10 to 40 mol%, more preferably from 10 to 35 mol%, and even more preferably from 20 to 30 mol%. The repeating unit A1 may be used alone or in combination of two or more kinds.

[0164] The polymer may further include a phenolic hydroxy group-containing repeating unit A2 represented by the following formula (A2). [ka]

[0165] In formula (A2), b1 is 0 or 1. When b1=0, b2 is an integer of 0 to 4, and when b1=1, b2 is an integer of 0 to 6. b3 is an integer of 1 to 3, with the proviso that when b1=0, 1≦b2+b3≦5, and when b1=1, 1≦b2+b3≦7.

[0166] In formula (A2), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0167] In formula (A2), X 3 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain.

[0168] In formula (A2), X 4is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Among these, a single bond, an ether bond or an ester bond is preferred, and a single bond or an ester bond is more preferred.

[0169] In formula (A2), A 2 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2 The saturated hydrocarbylene group may be linear, branched, or cyclic. Specific examples thereof include the following: 1 Examples of the saturated hydrocarbylene group represented by the following formula include the same as those exemplified above.

[0170] In formula (A2), R 2 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. The saturated hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R 1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0171] X 3 , X 4 and A 2 When both are single bonds, preferred examples of the repeating unit A2 include units derived from 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylnaphthalene, 6-hydroxy-2-vinylnaphthalene, etc. Among these, more preferred are repeating units represented by the following formula (A2-1), etc. [ka] (In the formula, R A and b3 are the same as above.)

[0172] X 1When R is other than a single bond, preferred examples of the repeating unit A2 include, but are not limited to, the repeating units A1 described above in which R is replaced with a hydrogen atom.

[0173] When the polymer contains the repeating unit A2, the content of the repeating unit A2 is preferably 30 to 90 mol %, more preferably 40 to 85 mol %, of the total repeating units of the polymer. However, when the polymer contains at least one of the repeating units represented by formula (B1) and the repeating unit represented by formula (B2), which will be described later, and the unit has a phenolic hydroxyl group as a substituent, the content of the repeating unit A2 is preferably within the above range. The repeating unit A2 may be used alone or in combination of two or more kinds.

[0174] The polymer may further include at least one selected from the repeating unit represented by the following formula (A3-1) (hereinafter also referred to as repeating unit A3-1) and the repeating unit represented by the following formula (A3-2) (hereinafter also referred to as repeating unit A3-2). [ka]

[0175] In formula (A3-1), c1 is 0 or 1. c2 is an integer of 0 to 2, and when it is 0, it represents a benzene skeleton, when it is 1, it represents a naphthalene skeleton, and when it is 2, it represents an anthracene skeleton. c3 is an integer satisfying 0≦c3≦5+2(c2)-c4. c4 is an integer of 1 to 3. c5 is 0 or 1. When c2 is 0, c3 is preferably an integer of 0 to 3 and c4 is an integer of 1 to 3, and when c2 is 1 or 2, c3 is preferably an integer of 0 to 4 and c4 is an integer of 1 to 3.

[0176] In formula (A3-2), d1 is an integer of 0 to 2. d2 is an integer of 0 to 2. d3 is an integer of 0 to 5. d4 is an integer of 0 to 2.

[0177] In formulas (A3-1) and (A3-2), R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0178] In formula (A3-1), A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2 - may be replaced by -O-. The saturated hydrocarbylene group may be linear, branched, or cyclic, and specific examples thereof include alkanediyl groups such as methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, and structural isomers thereof; cyclic saturated hydrocarbylene groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining these. When the saturated hydrocarbylene group contains an ether bond, when c1 in formula (A3-1) is 1, it may be located at any position except between the carbon atom at the α-position and the carbon atom at the β-position relative to the ester oxygen atom. When c1 is 0, the atom bonded to the main chain is an ether oxygen atom, and the second ether bond may be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position with respect to the ether oxygen atom. If the number of carbon atoms in the saturated hydrocarbylene group is 10 or less, sufficient solubility in an alkaline developer can be obtained, which is preferable.

[0179] In formula (A3-2), A 4 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OA 41 -It is. 41 is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * is a bond to a carbon atom of the main chain.

[0180] In formula (A3-1), R 3is a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. The saturated hydrocarbyl group, and the saturated hydrocarbyl part of the saturated hydrocarbyloxy group and the saturated hydrocarbylcarbonyloxy group may be linear, branched, or cyclic, and specific examples thereof include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, pentyl, and hexyl groups; cycloalkyl groups having 3 to 6 carbon atoms 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 c3 is 2 or more, each R 3 may be the same as or different from each other.

[0181] In formula (A3-2), R 4 and R 5 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom, R 4 and R 5 may be bonded to each other to form a ring together with the carbon atoms to which they are attached.

[0182] In formula (A3-2), R 6 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms.

[0183] In formula (A3-2), R 7 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom.

[0184] In formula (A3-1), X Ais an acid labile group when c4 is 1, and is a hydrogen atom or an acid labile group when c4 is 2 or 3, but at least one is an acid labile group. That is, the repeating unit A3-1 has at least one phenolic hydroxy group bonded to an aromatic ring protected with an acid labile group, or has a carboxy group bonded to an aromatic ring protected with an acid labile group. Such an acid labile group is not particularly limited and any of those that have been used in many known chemically amplified positive resist compositions and that are cleaved by an acid to give an acidic group can be used.

[0185] When a tertiary saturated hydrocarbyl group is selected as the acid labile group, it is preferable because a pattern with a small LER can be obtained even when a resist film is formed to have a thickness of, for example, 10 to 100 nm and a fine pattern with a line width of 45 nm or less is formed. The tertiary alkyl group preferably has 4 to 18 carbon atoms so that the obtained monomer for polymerization is obtained by distillation. In addition, the group bonded to the tertiary carbon atom of the tertiary saturated hydrocarbyl group may be a saturated hydrocarbyl group having 1 to 15 carbon atoms which may contain an ether bond or an oxygen atom-containing functional group such as a carbonyl group, and the groups bonded to the tertiary carbon atom may be bonded to each other to form a ring.

[0186] Specific examples of the group bonded to the tertiary carbon atom include a methyl group, an ethyl group, a propyl group, an adamantyl group, a norbornyl group, a tetrahydrofuran-2-yl group, a 7-oxanorbornan-2-yl group, a cyclopentyl group, a 2-tetrahydrofuryl group, a tricyclo[5.2.1.0 2,6 ]decyl group, tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, and 3-oxo-1-cyclohexyl group.

[0187] Examples of tertiary saturated hydrocarbyl groups having these as substituents include tert-butyl, tert-pentyl, 1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1,2-trimethylpropyl, 1-adamantyl-1-methylethyl, 1-methyl-1-(2-norbornyl)ethyl, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl, 1-methyl-1-(7-oxanorbornan-2-yl)ethyl, 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-ethylcyclopentyl, 1-methyl ... -propylcyclopentyl group, 1-isopropylcyclopentyl group, 1-cyclopentylcyclopentyl group, 1-cyclohexylcyclopentyl group, 1-(2-tetrahydrofuryl)cyclopentyl group, 1-(7-oxanorbornan-2-yl)cyclopentyl group, 1-methylcyclohexyl group, 1-ethylcyclohexyl group, 1-cyclopentylcyclohexyl group, 1-cyclohexylcyclohexyl group, 2-methyl-2-norbornyl group, 2-ethyl-2-norbornyl group, 8-methyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 8-ethyl-8-tricyclo[5.2.1.0 2,6 ]decyl group, 3-methyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 3-ethyl-3-tetracyclo[4.4.0.1 2,5 .1 7,10 ]dodecyl group, 2-methyl-2-adamantyl group, 2-ethyl-2-adamantyl group, 1-methyl-3-oxo-1-cyclohexyl group, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl group, 5-hydroxy-2-methyl-2-adamantyl group, and 5-hydroxy-2-ethyl-2-adamantyl group.

[0188] Further, the acid labile group may be a group represented by the following formula (A3-1-1). The group represented by formula (A3-1-1) is often used as an acid labile group, and is a useful option as an acid labile group that stably gives a pattern with a relatively rectangular interface between the pattern and the substrate. When X is a group represented by formula (A3-1-1), an acetal structure is formed. [ka]

[0189] In formula (A3-1-1), R L11 R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. L12 is a saturated hydrocarbyl group having a carbon number of 1 to 30. The saturated hydrocarbyl group may be linear, branched, or cyclic.

[0190] R L11 is appropriately selected depending on the design of the sensitivity of the decomposable group to acid. For example, if the design is to ensure relatively high stability and to decompose with strong acid, a hydrogen atom is selected, and if the design is to use relatively high reactivity to achieve high sensitivity to pH changes, a linear alkyl group is selected. Depending on the combination with the acid generator and basic compound to be blended in the resist composition, R L12 In the case where a relatively large alkyl group is selected at the end of the alkyl group, and the solubility change due to decomposition is large, R L11 As for R, the carbon atom bonded to the acetal carbon is preferably a secondary carbon atom. L11 Examples of the aryl group include an isopropyl group, a sec-butyl group, a cyclopentyl group, and a cyclohexyl group.

[0191] Of the acetal groups, R L12 is preferably a polycyclic alkyl group having 7 to 30 carbon atoms. L12 When R is a polycyclic alkyl group, it is preferable that a bond is formed between a secondary carbon atom constituting the polycyclic ring structure and an acetal oxygen. When the bond is formed on a secondary carbon atom of the ring structure, the polymer becomes a stable compound, and the storage stability of the resist composition is good and there is no deterioration in resolution, compared with when the bond is formed on a tertiary carbon atom. In addition, when R L12is bonded to a primary carbon atom via a linear alkyl group having one or more carbon atoms, the glass transition temperature (Tg) of the polymer is good, and the developed resist pattern does not suffer from shape defects due to baking.

[0192] Preferred examples of the group represented by formula (A3-1-1) include, but are not limited to, the following: L11 is the same as above. [ka]

[0193] Preferred examples of the repeating unit A3-2 include, but are not limited to, those shown below. A is the same as above. [ka]

[0194] Other acid labile groups include the phenolic hydroxyl group with a hydrogen atom of -CH 2 It is also possible to use one substituted with COO- (a tertiary saturated hydrocarbyl group). In this case, the tertiary saturated hydrocarbyl group may be the same as the tertiary saturated hydrocarbyl group used for protecting the phenolic hydroxy group described above.

[0195] When the polymer contains at least one selected from the repeating units A3-1 and A3-2, the content thereof is preferably 2 to 40 mol % of the total repeating units of the polymer, and the combined content of the repeating units A1, A3-1 and A3-2 is preferably 10 to 60 mol %, more preferably 10 to 50 mol %, and even more preferably 10 to 40 mol % of the total repeating units of the polymer. The repeating units A3-1 and A3-2 may be used alone or in combination of two or more.

[0196] The polymer may further include at least one selected from a repeating unit represented by the following formula (B1) (hereinafter also referred to as repeating unit B1), a repeating unit represented by the following formula (B2) (hereinafter also referred to as repeating unit B2), and a repeating unit represented by the following formula (B3) (hereinafter also referred to as repeating unit B3). [ka]

[0197] In the formulae (B1) and (B2), e and f each independently represent an integer of 0 to 4.

[0198] In formula (B3), R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. g1 is an integer of 0 to 5. g2 is an integer of 0 to 2.

[0199] In formula (B3), X 5 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain.

[0200] In formula (B3), A 5 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the -CH 2 The saturated hydrocarbylene group may be linear, branched, or cyclic. 1 Examples of the examples are similar to those given in the description of .

[0201] In formulas (B1) and (B2), R 11 and R 12are 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 hydrocarbylcarbonyloxy group, saturated hydrocarbyl group, and saturated hydrocarbyloxy group may be linear, branched, or cyclic. When e is 2 or more, each R 11 may be the same or different. When f is 2 or more, each R 12 may be the same as or different from each other.

[0202] In formula (B3), R 13 is an acetyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group or a cyano group, and may be a hydroxy group when g2 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 g1 is 2 or more, each R 13 may be the same as or different from each other.

[0203] When the repeating units B1 to B3 are used, in addition to the etching resistance of the aromatic ring, the addition of a ring structure to the main chain provides the effect of improving resistance to EB irradiation during etching and pattern inspection.

[0204] When the polymer contains repeating units B1 to B3, the content of the repeating units is preferably 5 mol % or more of the total repeating units of the polymer in order to obtain the effect of improving etching resistance. The upper limit of the content of the repeating units B1 to B3 is preferably 25 mol % or less, more preferably 20 mol % or less of the total repeating units of the polymer. When there is no functional group or when the functional group is other than a hydroxyl group, it is preferable that the amount of introduction is 25 mol % or less, since there is no risk of development defects occurring. The repeating units B1 to B3 may be used alone or in combination of two or more.

[0205] The content of at least one type selected from the repeating unit A2 and the repeating units B1 to B3 in all the repeating units of the polymer is preferably 50 mol % or more, more preferably 60 mol % or more.

[0206] The polymer may contain a commonly used (meth)acrylic acid ester unit protected by an acid labile group, or a (meth)acrylic acid ester unit having an adhesive group such as a lactone structure or a hydroxy group other than a phenolic hydroxy group. Although these repeating units allow fine adjustment of the properties of the resist film, they may not be included.

[0207] Examples of the (meth)acrylic acid ester unit having the adhesive group include a repeating unit represented by the following formula (B4) (hereinafter also referred to as repeating unit B4), a repeating unit represented by the following formula (B5) (hereinafter also referred to as repeating unit B5), and a repeating unit represented by the following formula (B6) (hereinafter also referred to as repeating unit B6). These units do not exhibit acidity and can be used auxiliary as units that impart adhesion to a substrate or units that adjust solubility. [ka]

[0208] In formulas (B4) to (B6), R A R are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.14 is -O- or a methylene group. 15 R is a hydrogen atom or a hydroxyl group. 16 is a saturated hydrocarbyl group having 1 to 4 carbon atoms. h is an integer of 0 to 3.

[0209] When the polymer contains the repeating units B4 to B6, the content thereof is preferably 0 to 20 mol %, more preferably 0 to 10 mol %, based on the total repeating units of the polymer. The repeating units B4 to B6 may be used alone or in combination of two or more kinds.

[0210] The polymer may further contain at least one selected from the group consisting of a repeating unit represented by the following formula (C1) (hereinafter also referred to as repeating unit C1), a repeating unit represented by the following formula (C2) (hereinafter also referred to as repeating unit C2), a repeating unit represented by the following formula (C3) (hereinafter also referred to as repeating unit C3), and a repeating unit represented by the following formula (C4) (hereinafter also referred to as repeating unit C4). [ka]

[0211] In formulas (C1) to (C4), R A are each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. 1 is a single bond or a phenylene group. 2 is *-C(=O)-OZ 21 -, *-C(=O)-NH-Z 21 -or*-OZ 21 -It is. 21 Z is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. 3 each independently represents a single bond, a phenylene group, a naphthylene group, or *-C(=O)-OZ 31 -It is. 31Z is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 4 are each independently a single bond, **-Z 41 -C(=O)-O-, **-C(=O)-NH-Z 41 -or**-OZ 41 -It is. It is. Z 41 Z is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 5 are each independently a single bond, *-Z 51 -C(=O)-O-, *-C(=O)-NH-Z 51 -or*-OZ 51 -It is. 51 Z is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 6 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, *-C(=O)-OZ 61 -, *-C(=O)-N(H)-Z 61 -or*-OZ 61 -It is. 61 represents an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. * represents a bond to a carbon atom in the main chain. ** represents Z 3 Represents a bond with .

[0212] Z 21 , Z 31 and Z 61The aliphatic hydrocarbylene group 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- Examples of the alkanediyl groups include a 2,3-diyl group, a butane-1,4-diyl group, a 1,1-dimethylethane-1,2-diyl group, a pentane-1,5-diyl group, a 2-methylbutane-1,2-diyl group, and a hexane-1,6-diyl group; cycloalkanediyl groups such as a cyclopropanediyl group, a cyclobutanediyl group, a cyclopentanediyl group, and a cyclohexanediyl group; and groups obtained by combining these groups.

[0213] Z 41 and Z 51 The hydrocarbylene group represented by the formula (I) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include, but are not limited to, those shown below. [ka] (In the formula, the dashed lines represent bonds.)

[0214] In formula (C1), R 31 and R 32are 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 methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, and tert-butyl groups; cyclic saturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 4-methylcyclohexyl, cyclohexylmethyl, norbornyl, and adamantyl groups; alkenyl groups having 2 to 20 carbon atoms, such as vinyl, allyl, propenyl, butenyl, and hexenyl groups; cyclic unsaturated hydrocarbyl groups having 3 to 20 carbon atoms, such as cyclohexenyl groups; aryl groups having 6 to 20 carbon atoms, such as phenyl, naphthyl, and thienyl groups; aralkyl groups having 7 to 20 carbon atoms, such as benzyl, 1-phenylethyl, and 2-phenylethyl groups; and groups obtained by combining these, with aryl groups being preferred. In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2 A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0215] Also, R 31 and R 32 and may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, the ring may be the same as R ct1 and R ct2 can be bonded to form a ring together with the sulfur atom to which they are bonded, similar to the examples given above.

[0216] Examples of the cation of the repeating unit C1 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0217] [ka]

[0218] [ka]

[0219] [ka]

[0220] [ka]

[0221] [ka]

[0222] [ka]

[0223] In formula (C1), M -is a non-nucleophilic counter ion. The non-nucleophilic counter ion is preferably a halide ion, a sulfonate anion, an imide anion, or a methide anion. Specific examples of the halide ion include a chloride ion and a bromide ion. Specific examples of the sulfonate anion (sulfonate ion) include fluoroalkylsulfonate ions such as a triflate ion, a 1,1,1-trifluoroethanesulfonate ion, and a nonafluorobutanesulfonate ion; arylsulfonate ions such as a tosylate ion, a benzenesulfonate ion, a 4-fluorobenzenesulfonate ion, and a 1,2,3,4,5-pentafluorobenzenesulfonate ion; and alkylsulfonate ions such as a mesylate ion and a butanesulfonate ion. Specific examples of the imide anion (imide ion) include a bis(trifluoromethylsulfonyl)imide ion, a bis(perfluoroethylsulfonyl)imide ion, and a bis(perfluorobutylsulfonyl)imide ion. Specific examples of the methide acid anion (methide ion) include imide ions such as bis(trifluoromethylsulfonyl)imide ion, bis(perfluoroethylsulfonyl)imide ion, and bis(perfluorobutylsulfonyl)imide ion; tris(trifluoromethylsulfonyl)methide ion, and tris(perfluoroethylsulfonyl)methide ion.

[0224] Other examples of the non-nucleophilic counter ion include anions represented by any of the following formulas (C1-1) to (C1-4). [ka]

[0225] In formula (C1-1), R fa is a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0226] The anion represented by formula (C1-1) is preferably one represented by the following formula (C1-1-1): [ka]

[0227] In formula (C1-1-1), Q 11 and Q 12 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms, and in order to improve the solvent solubility, it is preferable that at least one of them is a trifluoromethyl group. m is an integer of 0 to 4, and is particularly preferably 1. R fa1 is a hydrocarbyl group having 1 to 35 carbon atoms which may contain a heteroatom. The heteroatom is preferably an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or the like, and more preferably an oxygen atom. From the viewpoint of obtaining high resolution in the formation of a fine pattern, the hydrocarbyl group is preferably one having 6 to 30 carbon atoms.

[0228] In formula (C1-1-1), R fa1The hydrocarbyl group having 1 to 35 carbon atoms and 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 35 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, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, a nonyl group, an undecyl group, a tridecyl group, a pentadecyl group, a heptadecyl group, and an icosyl group; a cyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a 2-adamantyl group, a 1-adamantylmethyl group, a norbornyl group, a norbornyl group, and a cyclohexyl group. Examples of the alkyl group include cyclic saturated hydrocarbyl groups having 3 to 35 carbon atoms, such as bornylmethyl group, tricyclodecyl group, tetracyclododecyl group, tetracyclododecylmethyl group, and dicyclohexylmethyl group; unsaturated aliphatic hydrocarbyl groups having 2 to 35 carbon atoms, such as allyl group and 3-cyclohexenyl group; aryl groups having 6 to 35 carbon atoms, such as phenyl group, 1-naphthyl group, 2-naphthyl group, and 9-fluorenyl group; aralkyl groups having 7 to 35 carbon atoms, such as benzyl group and diphenylmethyl group; and groups obtained by combining these groups.

[0229] In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2 A part of the - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, etc. Examples of hydrocarbyl groups containing heteroatoms include a tetrahydrofuryl group, a methoxymethyl group, an ethoxymethyl group, a methylthiomethyl group, an acetamidomethyl group, a trifluoroethyl group, a (2-methoxyethoxy)methyl group, an acetoxymethyl group, a 2-carboxy-1-cyclohexyl group, a 2-oxopropyl group, a 4-oxo-1-adamantyl group, and a 3-oxocyclohexyl group.

[0230] In formula (C1-1-1), L a1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond, and from the viewpoint of synthesis, an ether bond or an ester bond is preferable, and an ester bond is more preferable.

[0231] Examples of the anion represented by formula (C1-1) include, but are not limited to, those shown below. In the following formula, Q 11 is the same as above, and Ac is an acetyl group. [ka]

[0232] [ka]

[0233] [ka]

[0234] [ka]

[0235] [ka]

[0236] [ka]

[0237] [ka]

[0238] [ka]

[0239] [ka]

[0240] [ka]

[0241] In formula (C1-2), R fb1 and R fb2 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1 Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fb1 and R fb2 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fb1 and R fb2 are bonded to each other and the group to which they are bonded (-CF 2 -SO 2 -N - -SO 2 -CF 2 -) may form a ring, in which case, R fb1 and R fb2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0242] In formula (C1-3), R fc1 , R fc2 and R fc3 are each independently a hydrocarbyl group having 1 to 40 carbon atoms which may contain a fluorine atom or a heteroatom. The hydrocarbyl group may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include R fa1Examples of the hydrocarbyl group represented by the formula R include the same as those exemplified above. fc1 , R fc2 and R fc3 is preferably a fluorine atom or a linear fluorinated alkyl group having 1 to 4 carbon atoms. fc1 and R fc2 are bonded to each other and the group to which they are bonded (-CF 2 -SO 2 -C - -SO 2 -CF 2 -) may form a ring, in which case, R fc1 and R fc2 The group obtained by bonding together is preferably a fluorinated ethylene group or a fluorinated propylene group.

[0243] In formula (c1-4), R fd is a hydrocarbyl group having 1 to 40 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 R fa1 Examples of the hydrocarbyl group represented by the formula (I) include the same as those exemplified above.

[0244] Examples of the anion represented by formula (C1-4) include, but are not limited to, those shown below. [ka]

[0245] [ka]

[0246] Further examples of the non-nucleophilic counter ion include anions having an aromatic ring substituted with an iodine atom or a bromine atom. Specific examples of such anions include those represented by the following formula (C1-5): [ka]

[0247] In formula (C1-5), x is an integer satisfying 1≦x≦3. y and z are integers satisfying 1≦y≦5, 0≦z≦3, and 1≦y+z≦5. y is preferably an integer satisfying 1≦y≦3, more preferably 2 or 3. z is preferably an integer satisfying 0≦z≦2.

[0248] In formula (C1-5), X BI is an iodine atom or a bromine atom, and when x and / or y are 2 or more, they may be the same or different.

[0249] In formula (C1-5), L 11 is a single bond, an ether bond or an ester bond, or a saturated hydrocarbylene group having 1 to 6 carbon atoms which may contain an ether bond or an ester bond. The saturated hydrocarbylene group may be linear, branched or cyclic.

[0250] In formula (C1-5), L 12 represents a single bond or a divalent linking group having 1 to 20 carbon atoms when x is 1, and represents a (x+1)-valent linking group having 1 to 20 carbon atoms when x is 2 or 3, and the linking group may contain an oxygen atom, a sulfur atom, or a nitrogen atom.

[0251] In formula (C1-5), R fe is a hydroxy group, a carboxy group, a fluorine atom, a chlorine atom, a bromine atom or an amino group, or a hydrocarbyl group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 20 carbon atoms, a hydrocarbylcarbonyl group having 2 to 20 carbon atoms, a hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, a hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms or a hydrocarbylsulfonyloxy group having 1 to 20 carbon atoms which may contain a fluorine atom, a chlorine atom, a bromine atom, a hydroxy group, an amino group or an ether bond, or feA )(R feB ), -N(R feC )-C(=O)-R feD Or -N(R feC )-C(=O)-ORfeD R feA and R feB R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. feC R is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. feD is an aliphatic hydrocarbyl group having 1 to 16 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 15 carbon atoms, and may contain a halogen atom, a hydroxy group, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 6 carbon atoms, or a saturated hydrocarbylcarbonyloxy group having 2 to 6 carbon atoms. The aliphatic hydrocarbyl group may be saturated or unsaturated and may be linear, branched, or cyclic. The hydrocarbyl group, hydrocarbyloxy group, hydrocarbylcarbonyl group, hydrocarbyloxycarbonyl group, hydrocarbylcarbonyloxy group, and hydrocarbylsulfonyloxy group may be linear, branched, or cyclic. When x and / or z is 2 or more, each R fe may be the same or different from each other.

[0252] Of these, R fe Examples of the hydroxyl group include -N(R feC )-C(=O)-R feD , -N(R feC )-C(=O)-OR feD , a fluorine atom, a chlorine atom, a bromine atom, a methyl group, a methoxy group, and the like are preferred.

[0253] In formula (C1-5), Rf 11 ~Rf 14 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, at least one of which is a fluorine atom or a trifluoromethyl group. 11 and Rf 12 may combine to form a carbonyl group. 13and Rf 14 are preferably both fluorine atoms.

[0254] Examples of the anion represented by formula (C1-5) include, but are not limited to, those shown below. In the following formula, X BI is the same as above. [ka]

[0255] [ka]

[0256] [ka]

[0257] [ka]

[0258] [ka]

[0259] [ka]

[0260] [ka]

[0261] [ka]

[0262] [ka]

[0263]

change

[0264]

change

[0265]

change

[0266]

change

[0267]

change

[0268]

change

[0269]

change

[0270]

change

[0271]

change

[0272]

change

[0273]

change

[0274] [ka]

[0275] [ka]

[0276] [ka]

[0277] As the non-nucleophilic counter ion, a fluorobenzenesulfonate anion bonded to an aromatic group containing an iodine atom as described in Japanese Patent No. 6648726, an anion having a mechanism of decomposition by acid as described in International Publication No. 2021 / 200056 and Japanese Patent Application Publication No. 2021-70692, an anion having a cyclic ether group as described in Japanese Patent Application Publication No. 2018-180525 and Japanese Patent Application Publication No. 2021-35935, and an anion as described in Japanese Patent Application Publication No. 2018-92159 can also be used.

[0278] Further, as the non-nucleophilic counter ion, anions of bulky benzenesulfonic acid derivatives not containing fluorine atoms, as described in JP 2006-276759 A, JP 2015-117200 A, JP 2016-65016 A, and JP 2019-202974 A, and benzenesulfonic acid anions and alkylsulfonic acid anions not containing fluorine atoms bonded to aromatic groups containing iodine atoms, as described in Japanese Patent No. 6645464, can also be used.

[0279] Further examples of the non-nucleophilic counter ion include an anion of bissulfonic acid described in JP 2015-206932 A, an anion of sulfonamide or sulfonimide having a sulfonic acid on one side and a different sulfonic acid on the other side described in WO 2020 / 158366 A, and an anion of sulfonic acid on one side and carboxylic acid on the other described in JP 2015-24989 A.

[0280] In formulae (C2) and (C3), L is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond, or a carbamate bond. Among these, from the viewpoint of synthesis, an ether bond, an ester bond, and a carbonyl group are preferred, and an ester bond and a carbonyl group are more preferred.

[0281] In formula (C2), Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 1 and Rf 2 In order to increase the acid strength of the generated acid, each of Rf is preferably a fluorine atom. 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Of these, Rf 3 and Rf 4 At least one of these is preferably a trifluoromethyl group.

[0282] In formula (C3), Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 Of these, Rf 5 and Rf 6 At least one of these is preferably a trifluoromethyl group.

[0283] In formulae (C2) and (C3), k1 and k2 each independently represent an integer of 0 to 3, with 1 being preferred.

[0284] Specific examples of the anion of the repeating unit C2 include, but are not limited to, those shown below. A is the same as above. [ka]

[0285] [ka]

[0286] [ka]

[0287] [ka]

[0288] [ka]

[0289] [ka]

[0290] [ka]

[0291] Specific examples of the anion of the repeating unit C3 include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0292] [ka]

[0293] [ka]

[0294] [ka]

[0295] [ka]

[0296] [ka]

[0297] [ka]

[0298] Specific examples of the anion of the repeating unit represented by formula (C4) include, but are not limited to, those shown below. In the following formula, R A is the same as above. [ka]

[0299] In formulas (C2) to (C4), A + is an onium cation. The onium cation is preferably a sulfonium cation represented by the following formula (cation-1) or an iodonium cation represented by the following formula (cation-2). [ka]

[0300] In formulas (cation-1) and (cation-2), R ct1 ~R ct5 are each independently a halogen atom or a hydrocarbyl group having 1 to 30 carbon atoms which may contain a heteroatom.

[0301] R ct1 ~R ct5 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0302] R ct1 ~R ct5 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 30 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, and a tert-butyl group; cyclic saturated hydrocarbyl groups having 3 to 30 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; alkenyl groups having 2 to 30 carbon atoms, such as a vinyl group, an allyl group, a propenyl group, a butenyl group, and a hexenyl group; cyclic unsaturated hydrocarbyl groups having 3 to 30 carbon atoms, such as a cyclohexenyl group; aryl groups having 6 to 30 carbon atoms, such as a phenyl group, a naphthyl group, and a thienyl group; aralkyl groups having 7 to 30 carbon atoms, such as a benzyl group, a 1-phenylethyl group, and a 2-phenylethyl group; and groups obtained by combining these, with an aryl group being preferred. In addition, a part of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0303] Also, R ct1 and R ct2 may be bonded to each other to form a ring together with the sulfur atom to which they are bonded. In this case, examples of the ring structure include those represented by the following formulas: [ka] (In the formula, the dashed line represents R ct3 It is a combination with .)

[0304] Specific examples of the sulfonium cation represented by formula (cation-1) include, but are not limited to, those shown below. [ka]

[0305] [ka]

[0306] [ka]

[0307] [ka]

[0308] [ka]

[0309]

change

[0310]

change

[0311]

change

[0312]

change

[0313]

change

[0314]

change

[0315]

change

[0316]

change

[0317]

change

[0318]

change

[0319]

change

[0320]

change

[0321]

change

[0322]

change

[0323]

change

[0324]

change

[0325]

change

[0326]

change

[0327]

change

[0328]

change

[0329]

change

[0330] Specific examples of the iodonium cation represented by formula (cation-2) include, but are not limited to, those shown below. [ka]

[0331] [ka]

[0332] Specific structures of the repeating units C1 to C4 include any combination of the above-mentioned anions and cations.

[0333] Among the repeating units C1 to C4, the repeating units preferred for processing the photomask blank include the repeating units C2 and C3, since they have optimal acid strength in designing the acid labile groups of the polymer.

[0334] The repeating units C1 to C4 are units that generate acid by irradiation with high energy rays. It is believed that the inclusion of these units in the polymer appropriately suppresses acid diffusion, making it possible to obtain a pattern with reduced LER. In addition, the inclusion of these units in the polymer suppresses the phenomenon in which acid volatilizes from the exposed area and reattaches to the unexposed area during baking in a vacuum, which is believed to be effective in reducing LER and reducing shape deterioration due to unwanted film loss in the unexposed area.

[0335] When the polymer contains the repeating units C1 to C4, the content thereof is preferably 0.1 to 30 mol %, more preferably 0.5 to 20 mol %, of the total repeating units of the polymer. The repeating units C1 to C4 may be used alone or in combination of two or more kinds.

[0336] The content of repeating units having an aromatic ring skeleton in all repeating units of the polymer is preferably 65 mol % or more, more preferably 75 mol % or more, and even more preferably 85 mol % or more. When the repeating units C1 to C4 are not included, it is preferable that all units have an aromatic ring skeleton.

[0337] Of all the repeating units of the polymer, the content of repeating unit A1 and at least one selected from repeating unit A2, repeating unit A3-1, repeating unit A3-2, and repeating units B1 to B3 is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more.

[0338] The polymer can be synthesized by copolymerizing each monomer that gives the repeating unit described above by a known method. The monomer may be protected with a protecting group, and in this case, the polymer can be synthesized by carrying out a deprotection reaction after polymerization. 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.

[0339] Alternatively, the polymer can be synthesized by copolymerizing monomers that do not include a monomer that provides the repeating unit A1, but include a monomer that provides the repeating unit A2, to synthesize a polymer, and then protecting the aromatic hydroxyl group of the polymer with an acetal group. Known methods for this 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, and any of these methods can be used here.

[0340] For example, in the case of a method using an acetal modifying agent (vinyl ether) represented by formula (AC-1) and an acid catalyst, specific examples of the acid catalyst include hydrochloric acid, sulfuric acid, nitric acid, methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, oxalic acid, methanesulfonic acid pyridine salt, etc. The reaction temperature is preferably 5° C. to 30° C., and the reaction time is preferably 0.2 to 10 hours, more preferably 0.5 to 6 hours.

[0341] In addition, a method of using an acetal modifying agent represented by formula (AC-2) (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, diisopropylethylamine, pyridine, 2,6-lutidine, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, etc. In this case, the reaction temperature is preferably −20 to 50° C., and the reaction time is preferably 0.2 to 10 hours, more preferably 0.5 to 6 hours.

[0342] However, in the method of using an acetalizing agent having a haloalkoxy group together with a base, a corrosive strong acid such as hydrochloric acid is generated, which corrodes metal production vessels and piping and may result in contamination with metal components that may cause defects in semiconductor products. In particular, in the advanced generation of semiconductors, the metal impurities in the raw materials used in the resist composition are required to be 10 ppb or less, so the method of using vinyl ether and an acid catalyst is preferred.

[0343] The polymer preferably has a weight average molecular weight (Mw) of 1000 to 50000, more preferably 2000 to 20000. 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 50000 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.

[0344] The polymer preferably has a narrow molecular weight distribution (Mw / Mn) of 1.0 to 2.0, preferably 1.0 to 1.9, and more preferably 1.0 to 1.8. When the polymer has such a narrow molecular weight distribution, no foreign matter is generated on the pattern after development, and the shape of the pattern is not deteriorated.

[0345] [Chemically amplified positive resist composition] The chemically amplified positive resist composition of the present invention contains a base polymer including the above-mentioned polymer. When an aromatic hydroxy group is generated in the polymer by a deprotection reaction with an acid, the aromatic hydroxy group has a higher acidity than an aliphatic hydroxy group, and therefore when a resist film is formed using the positive resist composition and developed with an alkaline developer, the dissolution contrast between the exposed and unexposed areas is increased, resulting in good resolution.

[0346] The base polymer may contain only the above-mentioned polymer, or may contain other polymers in addition to the above-mentioned polymer. Examples of other polymers include those containing repeating units A3-1 and / or A3-2 and at least one selected from repeating units A2, B1 to B3, and C1 to C4, and those containing a repeating unit having a known acid labile group such as a tertiary alkyl group or a tert-butoxycarbonyl group and at least one selected from repeating units A2, B1 to B3, and C1 to C4. In order to exert the effects of the present invention, it is preferable that the proportion of polymers containing repeating unit A1 is 30% or more of all base polymers contained in the resist composition.

[0347] When the base polymer contains other polymers in addition to the above-mentioned polymers, the content of the repeating unit A1 is preferably 10 to 40 mol %, more preferably 10 to 35 mol %, and even more preferably 20 to 30 mol % of the total repeating units of the polymers contained in the entire base polymer. The content of the repeating unit A2 is preferably 30 to 90 mol %, more preferably 40 to 85 mol % of the total repeating units of the polymers contained in the entire base polymer. However, when the repeating unit contains at least one of the repeating units represented by formula (B1) and the repeating unit represented by formula (B2) and the unit has a phenolic hydroxyl group as a substituent, it is preferable that the ratio is also included within the above range. The content of the repeating units B1 to B3 is preferably 5 mol % or more of the total repeating units of the polymers contained in the entire base polymer, and the upper limit is preferably 25 mol % or less, more preferably 20 mol % or less. The content of the repeating units B4 to B6 is preferably 0 to 20 mol %, more preferably 0 to 10 mol % of the total repeating units of the polymers contained in the base polymer. The content of the repeating units C1 to C4 is preferably from 0.1 to 30 mol %, and more preferably from 0.5 to 20 mol %, of all the repeating units of the polymer contained in the entire base polymer.

[0348] The content of repeating units having an aromatic ring skeleton in all repeating units of the polymer contained in the entire base polymer is preferably 65 mol % or more, more preferably 75 mol % or more, and even more preferably 85 mol % or more. When the repeating units C1 to C4 are not included, it is preferable that all units have an aromatic ring skeleton.

[0349] Of all the repeating units of the polymer contained in the entire base polymer, the content of repeating unit A1, and at least one selected from repeating unit A2, repeating unit A3-1, repeating unit A3-2, and repeating units B1 to B3 is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more.

[0350] 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 when 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 photomask production, which requires no defects, because the development process tends to be strong. 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 at 23°C for 100 seconds with a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH).

[0351] The reason why high resolution can be obtained by the acid labile group derived from the acetal modifier having a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom of the present invention is that in the unexposed area, the heteroatom derived from the oxygen atom or sulfur atom in the cyclic saturated heterocycle has a moderate affinity with the proton of the generated acid, so that it functions as an acid diffusion suppressing group, and the cyclic structure improves the etching resistance after pattern formation. On the other hand, in the exposed area, since the acetal structure exhibits a sharp reactivity to acid, the acid elimination reactivity is high, and since the alcohol having a cyclic saturated heterocycle generated after the acid elimination reaction has hydrophilicity, the exposed area is developed without leaving any residue during alkali development, so that the contrast between the exposed area and the unexposed area is improved. Due to these synergistic effects, good resolution can be obtained even in the formation of a positive fine pattern by alkali development, which is particularly advantageous for photomask processing in the generation of 10 nm node or finer.

[0352] [Organic solvents] The chemically amplified positive resist composition of the present invention may contain an organic solvent. There are no particular limitations on the organic solvent as long as it is capable of dissolving each of the components. Examples of such organic solvents include ketones such as cyclohexanone and methyl-2-n-pentyl ketone, as described in paragraphs

[0144] and

[0145] of JP-A-2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; ethers such as propylene glycol monomethyl ether (PGME), ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as PGMEA, 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, etc., can be added to accelerate the deprotection reaction of the acetal.

[0353] Among these organic solvents, 1-ethoxy-2-propanol, PGMEA, PGME, cyclohexanone, EL, γ-butyrolactone, and mixed solvents thereof are preferable.

[0354] When the chemically amplified positive resist composition of the present invention contains the organic solvent, 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. The organic solvent may be used alone or in combination of two or more kinds.

[0355] [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.

[0356] 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 partially fluorinated sulfonates described in JP-A-2008-111103, paragraphs

[0122] to

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

[0080] to

[0081] , etc. 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 A1.

[0357] As such a photoacid generator, a salt compound containing the anion shown below is preferable. [ka]

[0358] [ka]

[0359] [ka]

[0360] [ka]

[0361] [ka]

[0362]

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[0363]

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[0364]

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[0365]

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[0366]

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[0367]

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[0368]

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[0369]

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[0370]

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[0371]

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[0372]

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[0373]

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[0374]

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[0375]

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[0376]

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[0377]

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[0378]

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[0379]

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[0380]

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[0381]

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[0382]

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[0383]

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[0384]

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[0385]

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[0386]

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[0387]

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[0388]

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[0389]

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[0390]

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[0391]

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[0392]

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[0393]

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[0394]

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[0395]

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[0396]

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[0397]

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[0398]

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[0399]

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[0400]

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[0401]

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[0402]

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[0403]

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[0404]

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[0405]

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[0406]

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[0407]

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[0408]

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[0409]

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[0410]

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[0411]

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[0412]

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[0413]

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[0414]

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[0415] [ka]

[0416] [ka]

[0417] [ka]

[0418] Furthermore, as the photoacid generator, a salt compound containing an anion represented by the following formula (P1) is also preferred. [ka]

[0419] In formula (P1), m1 is 0 or 1. p is an integer of 1 to 3. q is an integer of 1 to 5. r is an integer of 0 to 3.

[0420] In formula (P1), L 1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond.

[0421] In formula (P1), L 2 is an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond.

[0422] In formula (P1), L A represents 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.

[0423] L A 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. A 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.

[0424] In formula (P1), 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.

[0425] In formula (P1), R 101 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 101A )(R 101B ), -N(R 101C )-C(=O)-R 101D Or -N(R101C )-C(=O)-OR 101D R 101A and R 101B R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 101C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 101D is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms.

[0426] R 101 , R 101A , R 101B and R 101C 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. 101 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 101 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.

[0427] R 101D The 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.

[0428] In formula (M-1), R 102represents 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.

[0429] R 102 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: A Examples of the hydrocarbylene group having 1 to 20 carbon atoms represented by the following formula include the same as those exemplified above.

[0430] R 102 Specific 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.

[0431] The anion represented by formula (P1) is preferably an anion represented by the following formula (P2). [ka]

[0432] In formula (P2), p, q, r, L 1 , L A and R 101 is the same as above. m2 is an integer of 1 to 4. R 102A 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. 102A may be the same as or different from each other.

[0433] Examples of the anion represented by formula (P1) include, but are not limited to, those shown below. [ka]

[0434] [ka]

[0435] [ka]

[0436] [ka]

[0437] [ka]

[0438] [ka]

[0439]

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[0440]

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[0441]

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[0442]

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[0443]

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[0444]

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[0445]

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[0446]

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[0447]

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[0448]

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[0449]

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[0450]

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[0451]

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[0452]

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[0453]

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[0454]

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[0455]

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[0456]

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[0457]

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[0458]

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[0459]

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[0460]

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[0461]

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[0462]

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[0463]

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[0464]

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[0465]

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[0466]

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[0467]

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[0468]

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[0469]

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[0470] The cation paired with the anion is preferably a sulfonium cation represented by the following formula (P3) or an iodonium cation represented by the following formula (P4). [ka]

[0471] In formulas (E) and (F), R 111 ~R 115 are each independently a halogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom.

[0472] R 111 ~R 115 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0473] R 111 ~R 115 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 decyl group, adamantyl group, and adamantylmethyl group; and aryl groups having 6 to 20 carbon atoms, such as phenyl group, naphthyl group, and anthracenyl group. 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 the -CH 2A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a carbonyl group, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond, a lactone ring, a sultone ring, a carboxylic anhydride (-C(=O)-OC(=O)-), a haloalkyl group, or the like.

[0474] Also, R 111 and R 112 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. In the explanation of formula (cation-1), R ct1 and R ct2 However, examples of the ring that can be formed by bonding together with the sulfur atom to which they are bonded include the same as those exemplified above.

[0475] Specific examples of the sulfonium cation represented by formula (P3) include, but are not limited to, those exemplified as the sulfonium cation represented by formula (cation-1). Specific examples of the iodonium cation represented by formula (P4) include, but are not limited to, those exemplified as the sulfonium cation represented by formula (cation-2).

[0476] The acid generated by the photoacid generator preferably has a pKa of -2.0 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. A chemically amplified positive resist composition containing such a photoacid generator catalyzes the deprotection reaction of the acid labile group of the polymer, resulting in good resolution.

[0477] When the chemically amplified positive resist composition of the present invention contains a photoacid generator, the content thereof 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. The photoacid generator may be used alone or in combination of two or more kinds.

[0478] [Quencher] The chemically amplified positive resist composition of the present invention preferably contains a quencher (acid diffusion inhibitor). Examples of the quencher include conventional basic compounds. Examples of 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.

[0479] 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.

[0480] An example of an onium salt of a carboxylic acid not fluorinated at the α-position is one represented by the following formula (Q1). [ka]

[0481] In formula (Q1), R 201 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.

[0482] R 201 The hydrocarbyl group represented by the formula (1) may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples thereof include alkyl groups having 1 to 40 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, 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 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.

[0483] In addition, some or all of the hydrogen atoms of the hydrocarbyl group may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, a nitrogen atom or a halogen atom, and the -CH 2A part of - may be substituted with a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom, and as a result, the group may contain a hydroxy group, a 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.

[0484] In formula (Q1), 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 (cation-1). Specific examples of the iodonium cation include the same as those exemplified as the iodonium cation represented by formula (cation-2).

[0485] Examples of the anion of the onium salt represented by formula (Q1) include, but are not limited to, those shown below. [ka]

[0486] [ka]

[0487] [ka]

[0488] As the quencher, a sulfonium salt of an iodized benzene ring-containing carboxylic acid represented by the following formula (Q2) can also be suitably used. [ka]

[0489] In formula (Q2), s is an integer of 1 to 5. t is an integer of 0 to 3, provided that 1≦s+t≦5. u is an integer of 1 to 3.

[0490] In formula (Q2), R 211 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 211A )-C(=O)-R 211B Or -N(R 211A )-C(=O)-OR 211B R 211A is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 221B is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. When t and / or u is 2 or more, each R 211 may be the same or different from each other.

[0491] In formula (Q2), L 21is a single bond or a (u+1)-valent linking group having 1 to 20 carbon atoms, and may contain at least one selected from an ether bond, a carbonyl group, an ester bond, an amide bond, a sultone ring, a lactam ring, a carbonate bond, a halogen atom, a hydroxy group, and a carboxy group. The saturated hydrocarbyl group, saturated hydrocarbyloxy group, saturated hydrocarbylcarbonyloxy group, and saturated hydrocarbylsulfonyloxy group may be linear, branched, or cyclic.

[0492] In formula (Q2), R 212 , R 213 and R 214 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 the -CH 2 A part of R may be substituted with an ether bond, an ester bond, a carbonyl group, an amide bond, a carbonate bond or a sulfonate bond. 212 and R 213 may be bonded to each other to form a ring together with the sulfur atom to which they are attached.

[0493] Specific examples of the compound represented by formula (Q2) include those described in JP 2017-219836 A. The compound represented by formula (Q2) has high absorption, a high sensitizing effect, and a high acid diffusion control effect.

[0494] As the quencher, a nitrogen atom-containing carboxylate compound represented by the following formula (Q3) can also be used. [ka]

[0495] In formula (Q3), R 221 ~R 224 Each independently represents a hydrogen atom, -L 22 -CO 2 - or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 221 and R 222 And, R 222 and R 223 and, or R 223 and R 224 and may be bonded to each other to form a ring together with the carbon atoms to which they are attached. 22 R is a single bond or a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 225 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a hydrogen atom or a heteroatom.

[0496] In formula (Q3), 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 22 -CO 2 - 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.

[0497] The carboxylic acid onium salt represented by formula (Q3) has at least one -L 22 -CO 2 - That is, R 221 ~R 224 At least one of the following is -L 22 -CO2 - and / or at least one of the hydrogen atoms bonded to the carbon atom of the ring R is -L 22 -CO 2 - is replaced by

[0498] In formula (Q3), 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 specific examples of the sulfonium cation in the formulae (C2) to (C4).

[0499] Examples of the anion of the compound represented by formula (Q3) include, but are not limited to, those shown below. [ka]

[0500] [ka]

[0501] [ka]

[0502] [ka]

[0503] [ka]

[0504] [ka]

[0505] 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]

[0506] 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.

[0507] When the chemically amplified positive resist composition of the present invention contains a quencher, the content thereof is preferably from 0 to 50 parts by mass, and more preferably from 0.1 to 40 parts by mass, relative to 80 parts by mass of the base polymer. The quencher may be used alone or in combination of two or more kinds.

[0508] When the chemically amplified positive resist composition of the present invention contains both a photoacid generator and a quencher, the content ratio of the photoacid generator to the quencher (photoacid generator / quencher) is preferably less than 3, more preferably less than 2.5, and even more preferably less than 2. When the content ratio of the photoacid generator to the quencher contained in the chemically amplified positive resist composition is within the above range, acid diffusion can be sufficiently suppressed, and excellent resolution and dimensional uniformity can be obtained.

[0509] [Fluorine atom-containing polymer] The chemically amplified positive resist composition of the present invention may contain a fluorine atom-containing polymer containing at least one selected from the repeating unit represented by the following formula (D1) (hereinafter also referred to as repeating unit D1), the repeating unit represented by the following formula (D2) (hereinafter also referred to as repeating unit D2), the repeating unit represented by the following formula (D3) (hereinafter also referred to as repeating unit D3), and the repeating unit represented by the following formula (D4) (hereinafter also referred to as repeating unit D4) for the purpose of increasing contrast, shielding chemical flare of acid during high-energy radiation exposure, and mixing of acid from the antistatic film during the process of applying an antistatic film material onto the resist film, thereby suppressing unexpected and unnecessary pattern deterioration. The fluorine atom-containing polymer also functions as a surfactant, and therefore can prevent reattachment of insoluble matter that may occur during the development process to the substrate, thereby exerting an effect against development defects. [ka]

[0510] In formulas (D1) to (D4), R B R are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 301 , R 302 , R 304 and R 305 R are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. 303 , R 306 , R 307 and R 308 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 203 , R 206 , R 207 and R 208 When Z is a hydrocarbyl group or a fluorinated hydrocarbyl group, an ether bond or a carbonyl group may be present between the carbon-carbon bond. n is an integer of 1 to 3. 1 is a (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.

[0511] R 301 , R 302 , R 304 and R 305 Examples of the saturated hydrocarbyl group having 1 to 10 carbon atoms represented by the formula (I) 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, and 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, and a norbornyl group. Of these, saturated hydrocarbyl groups having 1 to 6 carbon atoms are preferred.

[0512] R 303 , R 306 , R 307 and R 308 Examples of the hydrocarbyl group having 1 to 15 carbon atoms represented by the formula (1) 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 the like, with an alkyl group having 1 to 15 carbon atoms being preferred. Examples of the alkyl group include, in addition to those mentioned above, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a n-pentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group, a n-decyl group, a n-undecyl group, a n-dodecyl group, a n-tridecyl group, a n-tetradecyl group, and a 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 mentioned above are substituted with fluorine atoms.

[0513] Z 1 Examples of the (n+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 n hydrogen atoms have been removed from a cyclic saturated hydrocarbyl group having 3 to 20 carbon atoms. 1Examples of the (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the following formula include the above-mentioned (n+1)-valent hydrocarbon group in which at least one hydrogen atom has been substituted with a fluorine atom.

[0514] 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]

[0515] [ka]

[0516] [ka]

[0517] In addition, it is preferable that the fluorine atom-containing polymer further contains at least one selected from the repeating unit represented by the following formula (D5) (hereinafter also referred to as repeating unit D5) and the repeating unit represented by the following formula (D6) (hereinafter also referred to as repeating unit D6). [ka]

[0518] In formulas (D5) and (D6), R C R is each independently a hydrogen atom or a methyl group. 309 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. 310 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. 311is 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 - may be substituted with an ester bond or an ether bond. x is an integer of 1 to 3. y is an integer satisfying 0≦y≦5+2z-x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O- or *-C(=O)-NH-. 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.

[0519] R 309 and R 310 Examples of the hydrocarbyl group having 1 to 5 carbon atoms represented by the formula (1) 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. In addition, a group containing a heteroatom such as an oxygen atom, a sulfur atom, or a nitrogen atom may be present between the carbon-carbon bonds of these groups.

[0520] Also, -OR 309 is preferably a hydrophilic group. In this case, R 309 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.

[0521] Z 2 is preferably *-C(=O)-O- or *-C(=O)-NH-. C is preferably a methyl group. 2The 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.

[0522] 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]

[0523] [ka]

[0524] 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.

[0525] R 311 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.

[0526] 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]

[0527] [ka]

[0528] [ka]

[0529] [ka]

[0530] 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.

[0531] 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.

[0532] 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.

[0533] The Mw of the fluorine atom-containing polymer is preferably 2000 to 50000, more preferably 3000 to 20000. If the Mw is 2000 or more, the acid does not diffuse, the resolution does not deteriorate, and the stability over time is not impaired. If the Mw is 50000 or less, the solubility in the solvent is sufficient and no coating defects occur. Moreover, the fluorine atom-containing polymer preferably has an Mw / Mn of 1.0 to 2.2, more preferably 1.0 to 1.7.

[0534] When the chemically amplified positive resist composition of the present invention contains the fluorine atom-containing polymer, 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.

[0535] [Surfactants] The chemically amplified positive resist composition of the present invention may contain a commonly used surfactant in order to improve the coating property on the substrate. When using a surfactant, many of them are known, as described in JP-A-2004-115630, and the surfactant can be selected by referring to them. The content of the surfactant is preferably 0 to 5 parts by mass relative to 80 parts by mass of the base polymer. In addition, when the fluorine atom-containing polymer is contained in the chemically amplified positive resist composition of the present invention, the fluorine atom-containing polymer also plays the role of a surfactant, so the surfactant may not be contained.

[0536] The chemically amplified positive resist composition of the present invention can be prepared by dissolving the base polymer and, if necessary, components other than the base polymer in an organic solvent simultaneously or in any order to prepare a homogeneous resist solution. The resist solution obtained is preferably filtered. By using a filter made of nylon or polyethylene (PE) for filtration, gel components and particles contained in the resist solution can be effectively removed. Furthermore, it is preferable to use a filter with a pore size of 20 nm or less in order to maintain quality in the latest generation.

[0537] 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 thin (film thickness is 100 nm or less), the pattern is greatly affected by the loss of the pattern film in the alkaline developer, so if the dissolution rate of the unexposed portion is 10 nm / min or less, the pattern does not collapse and a fine pattern can be formed. 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 amount of film loss when the chemically amplified positive resist composition of the present invention is spin-coated on a 150 mm (6 inch) silicon wafer, baked at 110° C. for 240 seconds to form a resist film with a film thickness of 80 nm, and then developed with a 2.38 mass % TMAH aqueous solution at 23° C. for 80 seconds.

[0538] In addition, the dissolution rate of the exposed portion of the resist film obtained from the chemically amplified positive resist composition of the present invention in an alkaline developer is preferably 50 nm / sec or more, more preferably 80 nm / sec or more, from the viewpoint of improving development loading. By being 50 nm / sec or more, even if there 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 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 200 mm (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.

[0539] The acetal acid labile group of the present invention also has the effect of suppressing the influence of backscattering during electron beam writing, and therefore exhibits rectangular performance without the pattern shape becoming inversely tapered in a sensitivity range of 50 μC or more, preferably 80 μC or more, and more preferably 100 μC or more.

[0540] [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 high-energy rays (i.e., exposing the resist film with high-energy rays), and developing the resist film that has been irradiated with the pattern using an alkaline developer.

[0541] The substrate may be, for example, a substrate for manufacturing integrated circuits (Si, SiO, SiO 2 , SiN, SiON, TiN, WSi, BPSG, SOG, organic anti-reflection coating, etc.), or substrates for manufacturing transmission or reflection mask circuits (Cr, CrO, CrON, MoSi 2 , Si, SiO, SiO 2, SiON, SiONC, CoTa, NiTa, TaBN, SnO 2 The chemically amplified positive resist composition is applied onto the substrate by a method such as spin coating to a film thickness of 0.03 to 2 μm, and this is pre-baked on a hot plate preferably at 60 to 150° C. for 1 to 20 minutes, more preferably at 80 to 140° C. for 1 to 10 minutes, to form a resist film.

[0542] Next, the resist film is exposed to high energy rays to irradiate a pattern. Examples of the high energy rays include KrF excimer laser light, ArF excimer laser light, EB, and EUV having a wavelength of 3 to 15 nm. In the present invention, exposure using EB is preferred. In order to form a desired pattern, the exposure dose of EB is preferably 50 to 400 μC / cm. 2 In the resist composition of the present invention, the polymer containing an acetal type acid labile group described above has the effect of suppressing the influence of back scattering during EB writing, so that the irradiation is preferably performed at a dose of 50 μC / cm 2 More preferably, 80μC / cm 2 More preferably, 100 μC / cm 2 In the above sensitivity region, the pattern shape does not become inversely tapered, and rectangular performance can be exhibited.

[0543] 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.

[0544] 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.

[0545] 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.

[0546] The chemically amplified positive resist composition of the present invention is useful because it can form a pattern with particularly good isolated space resolution and small LER. In addition, 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. As such a substrate, a substrate having an outermost surface made of a material containing at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten, and tin is preferable. As such a substrate, a substrate having a sputtering film formed on the outermost surface of a chromium compound containing at least one light element 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. In other words, a transmission type or a reflection type mask blank coated with the above-mentioned chemically amplified positive resist composition is preferred.

[0547] 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.

[0548] The above-mentioned photomask blank having a chromium-based material in the outermost layer is very well known, as exemplified in JP2008-026500A, JP2007-302873A, and the like, as prior art therein. Detailed description will be omitted, but 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.

[0549] When a light-shielding film having an anti-reflection layer and a light-shielding layer is formed using a chromium-based material, the layers may be laminated in the order of an anti-reflection layer and a light-shielding layer from the surface side, or the anti-reflection layer, a light-shielding layer, and an anti-reflection layer. 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 carbonitride, chromium oxynitride, etc. may be used.

[0550] 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.

[0551] 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.

[0552] 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

[0553] 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. In the synthesis examples, the copolymer composition ratio is a molar ratio, and Mw is a weight average molecular weight converted into polystyrene by GPC measurement. The apparatus used is as follows. IR: Thermo Fisher Scientific NICOLET 6700 · 1 H-NMR: ECA-500 manufactured by JEOL Ltd.

[0554] [1] Synthesis of acetal modifier [Example 1-1] Synthesis of acetal modifying agent AC-1 [ka]

[0555] (1) Synthesis of intermediate In-1 Under a nitrogen atmosphere, sodium hydride (purity 55% by mass, 91.6 g) was suspended in THF (530 g) in a reaction vessel. The temperature in the reaction vessel was raised to 50°C, and a solution consisting of tetrahydrofurfuryl alcohol (224.7 g) and THF (90 g) was added dropwise. After the dropwise addition, the mixture was stirred for 2 hours at a temperature of 50°C in the reaction vessel. After the stirring, sodium iodide (30.0 g) was added, and methallyl chloride (180.7 g) was added dropwise while maintaining the temperature in the reaction vessel at 50 to 60°C. After the dropwise addition, the temperature in the reaction vessel was raised to 65°C, and the mixture was aged for 5 hours. After the aging, the reaction liquid was cooled, and water (620 g) was added to stop the reaction. The target product was extracted with hexane (620 g), subjected to normal aqueous work-up, and the solvent was removed by distillation. After that, 281.2 g of intermediate In-1 was obtained (yield 90%).

[0556] (2) Synthesis of acetal modifier AC-1 Under a nitrogen atmosphere, intermediate In-1 (281.2 g) and potassium t-butoxide (20.2 g) were dissolved in DMSO (300 g) in a reaction vessel. The temperature in the reaction vessel was raised to 80°C and aged for 12 hours. After aging, the reaction solution was cooled and water (300 g) was added to stop the reaction. The target product was extracted with hexane (500 g), subjected to a normal aqueous work-up, and the solvent was distilled off. After distillation purification, 268.1 g of the target acetal modifier AC-1 was obtained as a colorless oil (yield 95%).

[0557] IR spectrum data, nuclear magnetic resonance spectrum ( 1 H-NMR / DMSO-d 6 )The results are shown below. IR(D-ATR): ν= 2959, 2918, 2871, 1692, 1452, 1376, 1339, 1290, 1226, 1167, 1076, 1052, 1023, 922, 824, 444 cm -1 . 1H-NMR(600MHz in DMSO-d6): δ= 5.90(1H, m), 3.93(1H, m), 3.71(1H, m), 3.60(3H, m), 1.89-1.75(3H, m), 1.55(1H, m), 1.49(3H, s), 1.47(3H, s) ppm.

[0558] [Examples 1-2 to 1-8] Synthesis of acetal modifying agents AC-2 to AC-8 Acetal modifiers AC-2 to AC-8 were synthesized using the corresponding raw materials and known organic synthesis techniques. [ka]

[0559] [2] Polymer synthesis [Example 2-1] Synthesis of polymer P-1 In a 100 mL flask, 20 g of polyhydroxystyrene-acenaphthylene copolymer and 46.7 g of THF as a solvent were added. Then, under a nitrogen atmosphere, 0.5 g of methanesulfonic acid was added at about 25°C, and 4.4 g of acetal modifier AC-1 was added dropwise, and the mixture was reacted at room temperature for 4.5 hours. After the reaction was completed, 1.0 g of triethylamine was added, and the resulting reaction solution was dropped 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 0.7 g of acetic acid was added to perform a separation operation. The lower layer was distilled off, and 20 g of water and 0.9 g of pyridine were added to the resulting organic layer, and a separation operation was performed. The lower layer was distilled off, and 20 g of water was added to the resulting organic layer, and a water washing separation was performed (water washing separation was performed a total of 5 times). The organic layer after separation was concentrated and then dissolved in 40 g of PGME. The resulting solution was added dropwise to 600 g of water, and the resulting precipitate was filtered off, washed with water, and dried to obtain 20.3 g of the target polymer P-1, which was a white polymer. 1 H-NMR, 13 Measurement by C-NMR and GPC gave the following analytical results: [ka]

[0560] [Examples 2-2 to 2-15] Synthesis of polymers P-2 to P-15 Polymers P-2 to P-15 shown below were synthesized in the same manner as in Synthesis Example 1 or by a known method, except that the raw material polymer and / or acetal modifying agent was changed. [ka]

[0561] [ka]

[0562] [ka]

[0563] [Comparative Examples 1-1 to 1-6] Synthesis of Polymers cP-1 to cP-6 Polymers cP-1 to cP-6 shown below were synthesized by combining the respective monomers according to a known method. [ka]

[0564] [Reference Synthesis Examples 1 to 6] Synthesis of Polymers AP-1 to AP-6 Polymers AP-1 to AP-6 shown below were synthesized by combining the respective monomers according to a known method. [ka]

[0565] 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 polymers P-1 to P-15, AP-1 to AP-6, and cP-2 to cP-6 were 5 nm / min or less, and the dissolution rate of comparative polymer cP-1 was 14 nm / min.

[0566] [3] Preparation of chemically amplified positive resist composition [Examples 3-1 to 3-41, Comparative Examples 2-1 to 2-10] 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.

[0567] [Table 1]

[0568] [Table 2]

[0569] [Table 3]

[0570] In Tables 1 to 3, the structures of the photoacid generators PAG-1 to PAG-5, the quenchers Q-1 to Q-4, and the fluorine atom-containing polymers FP-1 to FP-5 are as follows. [ka]

[0571] [ka]

[0572] [ka]

[0573] [3] EB lithography evaluation [Examples 4-1 to 4-41, Comparative Examples 3-1 to 3-10] Each chemically amplified positive resist composition (R-1 to R-41, CR-1 to CR-10) 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.

[0574] Next, the resist film was exposed using an electron beam 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.

[0575] 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 a 200 nm isolated space at a ratio of 9:1 was taken as the resolution (limit IS resolution), and the LER of 200 nm LS was measured using an SEM. For the development loading evaluation, the exposure dose (μC / cm) that resolves a 1:1 LS of the design 200 nm at a ratio of 1:1 was used within the substrate surface. 2 The space dimensions of a 200nm LS pattern formed by the 200nm LS pattern with dummy patterns of densities of 15%, 25%, 33%, 45%, 50%, 55%, 66%, 75%, 85%, and 95% were measured by SEM, and the dimensional differences of the dense and sparse patterns were compared. The pattern shape was visually judged to be rectangular or not.

[0576] The dissolution rate of the exposed area was measured by spin-coating a resist solution onto an 8-inch silicon wafer, baking it at 110°C for 60 seconds to form a resist film with a thickness of 90 nm, and then measuring the exposure dose (mJ / cm2) required to resolve a 1:1 line and space (LS) of 200 nm at 1:1. 2 ) and exposed to KrF excimer laser light, baked at 110°C for 60 seconds, and then developed at 23°C with a 2.38% by mass TMAH aqueous solution using a resist development analyzer (RDA-800 manufactured by LithoTech Japan Co., Ltd.), and calculations were performed. The results are shown in Tables 4 to 6.

[0577] [Table 4]

[0578] [Table 5]

[0579] [Table 6]

[0580] The chemically amplified positive resist compositions of the present invention (R-1 to R-41) all exhibited good isolated space (IS) resolution, LER, and pattern rectangularity, and showed suppressed development loading, compared to the comparative resist compositions (CR-1 to CR-10).

[0581] [4] Residual defect evaluation [Examples 5-1 to 5-41, Comparative Examples 4-1 to 4-10] The resist compositions (R-1 to R-41, CR-1 to CR-10) were applied to a reflective mask blank for EUV exposure masks, and the substrate was fully patterned with the optimal exposure dose for each resist composition using an electron beam exposure device (EBM-5000plus, manufactured by NuFlare Technology, Inc., acceleration voltage 50 kV), and PEB was performed for 600 seconds at 110 ° C., and 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 Tables 7 to 9.

[0582] [Table 7]

[0583] [Table 8]

[0584] [Table 9]

[0585] The chemically amplified positive resist compositions of the present invention (R-1 to R-41) all showed a smaller total number of defects after development than the comparative resist compositions (CR-1 to CR-10).

[0586] [5] Dry etching resistance evaluation [Examples 6-1 to 6-41, Comparative Examples 5-1 to 5-10] 2 g of each polymer (P-1 to P-41, CP-1 to CP-10) shown in Tables 1 and 2 was dissolved in 10 g of cyclohexanone, and the polymer solution was filtered through a 0.2 μm filter. The polymer solution was spin-coated onto a 152 mm square mask blank having a Cr film on the outermost surface to form a film with a thickness of 300 nm, and evaluated under the following conditions. Chlorine gas etching test: The difference in thickness of the polymer film before and after etching was determined using a mask dry etching device Gen-4 manufactured by Plasma Thermo Corporation. The etching conditions are as follows: Chamber pressure: 6.0mTorr RF power 700V Cl 2 Gas flow rate: 185sccm O 2 Flow rate 55sccm He flow rate 9sccm Time 75sec In this evaluation, a film with a small difference in film thickness, that is, a film with a small amount of reduction, shows good etching resistance. The results of the dry etching resistance are shown in Tables 10 to 13.

[0587] [Table 10]

[0588] [Table 11]

[0589] [Table 12]

[0590] From the results shown in Tables 10 to 13, the polymer of the present invention has Cl 2 / O 2 It was confirmed that the film had excellent dry etching resistance in SiO2-based gases.

[0591] The polymer, chemically amplified positive resist composition and method of forming a resist pattern of the present invention are useful for photolithography in the manufacture of semiconductor devices, particularly in the processing of transmission and reflection photomask blanks.

Claims

1. An acetal modifying agent which gives a group having a cyclic saturated heterocycle containing an oxygen atom or a sulfur atom which serves as a protecting group for an aliphatic or aromatic hydroxy group.

2. The acetal modifying agent according to claim 1, which provides a group that serves as a protecting group for an aromatic hydroxy group.

3. The acetal modifying agent according to claim 1, which is a compound represented by the following formula (AC-1) or (AC-2): 【Chemistry 1】 (In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 15 carbon atoms. L1 and R L2 and may be bonded to each other to form a ring together with the carbon atom to which they are attached, R L5 ~R L7 Any two of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L3 and R L4 and may be bonded to each other to form a ring together with the carbon atom to which they are attached, R L8 and R L9 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 are each independently a group containing a saturated heterocyclic ring containing an oxygen atom or a sulfur atom. X is a chlorine atom, a bromine atom or an iodine atom. m1 and m2 each independently represent an integer of 0 to 3.

4. A polymer comprising a repeating unit A1 having, at its side chain, a structure in which an aromatic hydroxy group is protected with an acid labile group represented by the following formula (AL-1) or (AL-2), and which becomes alkali-soluble upon being deprotected by the action of an acid. 【Chemistry 2】 (In the formula, R L1 , R L2 , R L5 , R L6 and R L7 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 15 carbon atoms. L1 and R L2 and may be bonded to each other to form a ring together with the carbon atom to which they are attached, R L5 ~R L7 Any two of may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R L3 , R L4 , R L8 and R L9 are each independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. L3 and R L4 and may be bonded to each other to form a ring together with the carbon atom to which they are attached, R L8 and R L9 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. W 1 are each independently a group containing a saturated heterocyclic ring containing an oxygen atom or a sulfur atom. m1 and m2 each independently represent an integer of 0 to 3. The dashed line represents a bond to the oxygen atom of the aromatic hydroxy group.

5. 5. The polymer according to claim 4, wherein the repeating unit A1 is represented by the following formula (A1): 【Chemistry 3】 (In the formula, a1 is 0 or 1. When a1=0, a2 is an integer of 0 to 4, and when a1=1, a2 is an integer of 0 to 6. A3 is an integer of 1 to 3, with the proviso that when a1=0, 1≦a2+a3≦5, and when a1=1, 1≦a2+a3≦7. 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. X 2 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. 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 hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom. R is an acid labile group represented by formula (AL-1) or (AL-2).

6. The polymer according to claim 4, further comprising a repeating unit A2 containing a phenolic hydroxy group represented by the following formula (A2): 【Chemistry 4】 (In the formula, b1 is 0 or 1. When b1=0, b2 is an integer from 0 to 4, and when b1=1, b2 is an integer from 0 to 6. When b1=0, b2+b3 is an integer from 1 to 3, with the proviso that 1≦b2+b3≦5 and when b1=1, 1≦b2+b3≦7. 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. X 4 is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. 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 is a hydrocarbyl group having 1 to 20 carbon atoms which may contain a halogen atom or a heteroatom.

7. 7. The polymer according to claim 6, wherein the repeating unit A2 is represented by the following formula (A2-1): 【Chemistry 5】 (In the formula, R A and b3 are the same as above.)

8. The polymer according to claim 4, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (A3-1) and a repeating unit represented by the following formula (A3-2): 【Chemistry 6】 (In the formula, c1 is 0 or 1. c2 is an integer from 0 to 2. c3 is an integer satisfying 0≦c3≦5+2(c2)−c4. c4 is an integer from 1 to 3. c5 is 0 or 1. d1 is an integer from 0 to 2. d2 is an integer from 0 to 2. d3 is an integer from 0 to 5. d4 is an integer from 0 to 2. R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. A 3 is a single bond or a saturated hydrocarbylene group having 1 to 10 carbon atoms, and the —CH 2 - may be replaced by -O-. A 4 is a single bond, a phenylene group, a naphthylene group, or *-C(=O)-O-A 41 - is. 41 is an aliphatic hydrocarbylene group having 1 to 20 carbon atoms which may contain a hydroxy group, an ether bond, an ester bond or a lactone ring, or a phenylene group or naphthylene group. * is a bond to a carbon atom of the main chain. R 3 represents a halogen atom, a saturated hydrocarbyl group having 1 to 6 carbon atoms which may be substituted with a halogen atom, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms which may be substituted with a halogen atom, or a saturated hydrocarbylcarbonyloxy group having 2 to 8 carbon atoms which may be substituted with a halogen atom. R 4 and R 5 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom; R 4 and R 5 may be bonded to each other to form a ring together with the carbon atoms to which they are attached. R 6 each independently represents a fluorine atom, a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkoxy group having 1 to 5 carbon atoms. R 7 are each independently a hydrocarbyl group having 1 to 10 carbon atoms which may contain a heteroatom. X A is an acid labile group when c4 is 1, and is a hydrogen atom or an acid labile group when c4 is 2 or 3, but at least one of them is an acid labile group.

9. The polymer according to claim 4, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (B1), a repeating unit represented by the following formula (B2), and a repeating unit represented by the following formula (B3): 【Chemistry 7】 (In the formula, e and f each independently represent an integer of 0 to 4. g1 represents an integer of 0 to 5. g2 represents an integer of 0 to 2. R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X 5 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. * is a bond to a carbon atom in the main chain. A 5 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 11 and R 12 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 13 is an acetyl group, a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxyhydrocarbyl group having 2 to 20 carbon atoms, a saturated hydrocarbylthiohydrocarbyl group having 2 to 20 carbon atoms, a halogen atom, a nitro group, or a cyano group, and when g2 is 1 or 2, it may be a hydroxy group.

10. The polymer according to claim 4, further comprising at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (C1), a repeating unit represented by the following formula (C2), a repeating unit represented by the following formula (C3), and a repeating unit represented by the following formula (C4): 【Chemistry 8】 (In the formula, R A each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z 1 is a single bond or a phenylene group. Z 2 teeth,* 1 -C(=O)-O-Z 21 -, * 1 -C(=O)-NH-Z 21 -or* 1 -O-Z 21 - is. 21 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, or a divalent group obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group.* 1 Is, Z 1 Represents a bond with . Z 3 each independently represents a single bond, a phenylene group, a naphthylene group, or * 2 -C(=O)-O-Z 31 - is. 31 is an aliphatic hydrocarbylene group having 1 to 10 carbon atoms, a phenylene group, or a naphthylene group, and the aliphatic hydrocarbylene group may contain a hydroxy group, an ether bond, an ester bond, or a lactone ring. 2 represents a bond to a carbon atom in the main chain. Z 4 each independently represents a single bond, * 3 -Z 41 -C(=O)-O-, * 3 -C(=O)-NH-Z 41 -or* 3 -O-Z 41 - is. is. Z 41 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 3 Is, Z 3 Represents a bond with . Z 5 each independently represents a single bond, * 4 -Z 51 -C(=O)-O-, * 4 -C(=O)-NH-Z 51 -or* 4 -O-Z 51 - is. 51 is a hydrocarbylene group having 1 to 20 carbon atoms which may contain a heteroatom. 4 Is, Z 4 Represents a bond with . Z 6 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, * 2 -C(=O)-O-Z 61 -, * 2 -C(=O)-N(H)-Z 61 -or* 2 -O-Z 61 - is. 61 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a phenylene group substituted with a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxy group.* 2 represents a bond to a carbon atom in the main chain. * indicates a bond to a carbon atom in the main chain. R 31 and R 32 are each independently a hydrocarbyl group having 1 to 20 carbon atoms which may contain a heteroatom. 31 and R 32 may be bonded to each other to form a ring together with the sulfur atom to which they are attached. L is a single bond, an ether bond, an ester bond, a carbonyl group, a sulfonate ester bond, a carbonate bond or a carbamate bond. Rf 1 and Rf 2 are each independently a fluorine atom or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 3 and Rf 4 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. Rf 5 and Rf 6 are each independently a hydrogen atom, a fluorine atom, or a fluorinated saturated hydrocarbyl group having 1 to 6 carbon atoms. 5 and Rf 6 cannot simultaneously become a hydrogen atom. M - is a non-nucleophilic counterion. A + is an onium cation. k1 and k2 each independently represent an integer of 0 to 3.

11. A chemically amplified positive resist composition comprising a base polymer comprising the polymer according to any one of claims 4 to 10.

12. The chemically amplified positive resist composition according to claim 11, further comprising an organic solvent.

13. 12. The chemically amplified positive resist composition according to claim 11, further comprising a photoacid generator capable of generating an acid having an acid strength (pKa) of -2.0 or more.

14. 12. The chemically amplified positive resist composition according to claim 11, wherein the photoacid generator contains an anion represented by the following formula (P1): 【Chemistry 9】 (In the formula, m1 is 0 or 1. p is an integer from 1 to 3. q is an integer from 1 to 5. r is an integer from 0 to 3. L 1 is a single bond, an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. L 2 is an ether bond, an ester bond, a sulfonate ester bond, a carbonate bond or a carbamate bond. L A represents 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. Rf 1 and Rf 2 are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, provided that at least one of them is a fluorine atom or a trifluoromethyl group. R 101 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 101A )(R 101B ), -N(R 101C )-C(=O)-R 101D Or -N(R 101C )-C(=O)-O-R 101D It is. 101A and R 101B are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 101C is a hydrogen atom or a saturated hydrocarbyl group having 1 to 6 carbon atoms. 101D is a saturated hydrocarbyl group having 1 to 6 carbon atoms or an unsaturated aliphatic hydrocarbyl group having 2 to 8 carbon atoms. R 102 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.

15. The chemically amplified positive resist composition according to claim 11, further comprising a quencher.

16. The chemically amplified positive resist composition according to claim 11, further comprising a fluorine atom-containing polymer containing 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): 【Chemistry 10】 (In the formula, R B each independently represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 301 , R 302 , R 304 and R 305 are each independently a hydrogen atom or a saturated hydrocarbyl group having 1 to 10 carbon atoms. R 303 , R 306 , R 307 and R 308 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 203 , R 206 , R 207 and R 208 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. n is an integer from 1 to 3. Z 1 is a (n+1)-valent hydrocarbon group having 1 to 20 carbon atoms or a (n+1)-valent fluorinated hydrocarbon group having 1 to 20 carbon atoms.

17. The chemically amplified positive resist composition according to claim 16, wherein the fluorine atom-containing polymer further comprises 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 11】 (In the formula, R C are each independently a hydrogen atom or a methyl group. R 309 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 310 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 311 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. x is an integer of 1 to 3. y is an integer satisfying 0≦y≦5+2z−x. z is 0 or 1. Z 2 is a single bond, *-C(=O)-O-, or *-C(=O)-NH-. Z 3 is a single bond, -O-, *-C(=O)-O-Z 31 -Z 32 - or *-C(=O)-NH-Z 31 -Z 32 - is. 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.)

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

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

20. 12. The chemically amplified positive resist composition according to claim 11, wherein the exposed area of ​​a resist film obtained from the chemically amplified positive resist composition has a dissolution rate in an alkaline developer of 50 nm / sec or more.

21. 12. 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 claim 11; irradiating the resist film with a pattern using high-energy rays; and developing the resist film irradiated with the pattern using an alkaline developer.

22. 22. The method of forming a resist pattern according to claim 21, wherein the high-energy radiation is KrF excimer laser light, ArF excimer laser light, an electron beam, or extreme ultraviolet light having a wavelength of 3 to 15 nm.

23. 22. The method for forming a resist pattern according to claim 21, 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.

24. 22. The chemically amplified positive resist composition according to claim 21, wherein the substrate is a transmission or reflection mask blank.

25. A transmission or reflection mask blank coated with the chemically amplified positive resist composition according to claim 11.

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