Chemically amplified positive resist composition and resist pattern forming process

Abstract

The objective of this invention is to provide a chemically amplified positive resist composition that yields resist patterns with improved resolution during pattern formation and improved LER and CDU, fewer defects, and can be inspected using a short wavelength of 300-400 nm, and to provide a method for forming resist patterns. The solution to this objective is a chemically amplified positive resist composition comprising, in predetermined amounts: (A) an onium salt compound represented by formula (A1), (B) a base polymer containing repeating units represented by formula (B1) that decomposes under acid and increases solubility in alkaline developing solutions, but excluding polymers containing repeating units with lactone rings, and (C) a photoacid generator.

Description

Technical Field

[0001] This invention relates to chemically amplified positive inhibitor compositions and methods for forming inhibitor patterns. Prior Technology

[0002] In recent years, with the increasing integration and speed of LSI (Light Separation Technology), the miniaturization of patterns has also progressed rapidly. The processing of patterns smaller than 0.2 μm primarily utilizes chemical amplification inhibitor compositions with acid as a catalyst. Furthermore, exposure sources employ high-energy rays such as ultraviolet light, far-ultraviolet light, and electron beams (EB). Especially in EB lithography, which is used as an ultra-micro processing technology, it has become indispensable for the processing of blank photomasks when fabricating photomasks for semiconductor manufacturing.

[0003] Polymers containing a large number of aromatic backbones with acidic side chains, such as polyhydroxystyrene, are useful as resist compositions for KrF lithography using KrF excimer lasers. However, they exhibit significant absorption for light around 200 nm, making them unsuitable as resist compositions for ArF lithography using ArF excimer lasers. Nevertheless, they are important materials for EB lithography resist compositions or extreme ultraviolet (EUV) lithography resist compositions, which are powerful techniques for forming patterns with smaller processing limits than ArF excimer lasers, due to their high etch resistance.

[0004] Typically, the base polymers of resist compositions for positive EB lithography and resist compositions for EUV lithography primarily use acids generated from photoacid generators by irradiation with high-energy rays as catalysts. These acids deprotect the acid-degradable protecting groups (acid-unstable groups) of the acidic functional groups of the phenolic side chains of the base polymer, making the material soluble in alkaline developing solutions.

[0005] Various improvements have been made to control sensitivity and pattern profile by adjusting the selection, combination, and processing conditions of the materials used in the inhibitor composition. One such improvement addresses the issue of acid diffusion. Since acid diffusion significantly affects the sensitivity and resolution of chemically amplified inhibitor compositions, much research has been conducted on this topic.

[0006] Patent documents 1 and 2 describe examples of suppressing acid diffusion and reducing roughness (LER) by increasing the volume of benzenesulfonic acid generated from a photoacid generator through exposure. However, the suppression of acid diffusion in the aforementioned acid generators has not been sufficient to date, and the development of acid generators with smaller diffusion is desired.

[0007] Patent document 3 describes an example of controlling acid diffusion by bonding sulfonic acid generated during exposure to the polymer used in the inhibitor composition. This method of containing repeating units of acid generated during exposure in the base polymer to suppress acid diffusion is effective when obtaining patterns with small LER (Low Residue). However, depending on the structure and incorporation rate of such repeating units, there are sometimes problems with the solubility of the base polymer with the repeating units of acid generated during exposure in organic solvents.

[0008] It is believed that in order to suppress acid diffusion, in addition to the aforementioned methods of increasing the volume of generated acid, there are also methods of improving acid diffusion control agents (quenchers). Acid diffusion control agents, which suppress acid diffusion, are practically essential components used to improve the performance of resist compositions. Various studies have been conducted on acid diffusion control agents to date, generally using amines and weak acid onium salts. Regarding weak acid onium salts, Patent Document 4 describes how adding triphenylsulphine acetate can form a good resist pattern without T-top formation, without linewidth differences between isolated and dense patterns, and without standing waves. Patent Document 5 describes how adding ammonium sulfonate or ammonium carboxylate salts can improve sensitivity, resolution, and exposure latitude. Furthermore, Patent Document 6 describes resist compositions for KrF and EB photolithography containing a combination of photoacid generators that produce fluorine-containing carboxylic acids, exhibiting excellent resolution and improved process tolerances such as exposure latitude and depth of focus. These are used in KrF, EB, or F2 photolithography.

[0009] Patent document 7 describes a positive photosensitive composition for ArF lithography containing carboxylic acid onium salts. These compositions utilize the exchange between a strong acid (sulfonic acid) and a weak acid onium salt generated from a photoacid generator upon exposure, forming a weak acid and a strong acid onium salt. This process replaces the highly acidic strong acid (sulfonic acid) with a weak acid (carboxylic acid), thereby inhibiting the acid decomposition reaction of unstable acid groups and (controlling) the reduction of acid diffusion distance, thus functioning as an acid diffusion control agent.

[0010] However, when using the aforementioned inhibitor compositions containing carboxylic acid onium salts and fluorocarboxylic acid onium salts for patterning, the problem of large LER still exists in recent years due to the further progress in miniaturization. Therefore, it is hoped that acid diffusion control agents that can further reduce LER will be developed.

[0011] In addition, in order to reduce LER, a method is to add a large amount of acid diffusion control agent relative to the acid generator to suppress acid diffusion. However, in this case, since the onium salt type acid diffusion control agent has poor solubility in the inhibitor solvent, it will generate agglomerates and cause defects.

[0012] Furthermore, with the miniaturization of patterns formed in recent years, inspection devices with short inspection wavelengths are required to detect minute defects. However, since resist materials absorb inspection light with wavelengths below 400nm, the resist film may deteriorate due to photosensitivity.

[0013] Patent Document 8 describes a resist composition containing triphenylstyrene salt. However, in response to recent requirements for dimensional uniformity (CDU), the resist composition described in Patent Document 8 has insufficient CDU. [Previous Technical Documents] [Patent Literature]

[0014] [Patent Document 1] Japanese Patent Application Publication No. 2009-53518 [Patent Document 2] Japanese Patent Application Publication No. 2010-100604 [Patent Document 3] Japanese Patent Application Publication No. 2011-22564 [Patent Document 4] Japanese Patent No. 3955384 [Patent Document 5] Japanese Patent Application Publication No. 11-327143 [Patent Document 6] Japanese Patent No. 4231622 [Patent Document 7] Japanese Patent No. 4226803 [Patent Document 8] Japanese Patent Application Publication No. 2016-6495 [Patent Document 9] Japanese Patent No. 4575479 Summary of the Invention

[0015] [The problem that the invention aims to solve]

[0016] The present invention is made in view of the foregoing circumstances, and aims to provide a chemically amplified positive resist composition that can obtain resist patterns with improved resolution during pattern formation and improved LER and CDU, fewer defects, and can be used for defect inspection with a short wavelength of 300~400nm, as well as a method for forming resist patterns. [Methods for solving problems]

[0017] After repeated and in-depth explorations to achieve the aforementioned objectives, the inventors obtained the following insights, which led to the completion of this invention: an inhibitor composition containing an acid diffusion control agent composed of an onium salt compound having a specific phenyl oxide anion can obtain a pattern exhibiting good resolution and pattern shape, with improved LER and CDU, fewer defects, and no absorption of short wavelength light of 300-400 nm.

[0018] That is, the present invention provides the following chemically amplified positive inhibitor composition and inhibitor pattern formation method. 1. A chemically amplified positive inhibitor composition, comprising: (A) The onium salt compound represented by the following formula (A1), (B) Basic polymers, including polymers containing repeating units represented by formula (B1) that decompose under acid and increase their solubility in alkaline developing solutions, but excluding polymers containing repeating units with lactone rings, and (C) Photoacid generator; Of all the repeating units in the aforementioned basic polymer, the content of repeating units with an aromatic ring skeleton is 65 mol% or more. The aforementioned photoacid generator contained less than 4% of the onium salt compound represented by formula (A1). The content of the aforementioned photoacid generator is 5 parts by mass or more relative to 80 parts by mass of the polymer, and The total content of the onium salt compound represented by formula (A1) and the aforementioned photoacid generator is 10 parts by mass or more relative to 80 parts by mass of the polymer. [Chemistry 1] In the formula, R1 to R5 are independently hydrogen atoms, halogen atoms, nitro groups, cyano groups, aldehyde groups, or hydrocarbon groups with 1 to 18 carbon atoms that may contain heteroatoms, -C(O)OR6, -C(O)R7, -OR8, -S(O)2R9, or -S(O)2N(R10)2. R6 and R7 are independently hydrocarbon groups with 1 to 19 carbon atoms that may contain heteroatoms. R8 and R9 are independently hydrocarbon groups with 1 to 20 carbon atoms that may contain heteroatoms. R10 is independently hydrogen atoms or hydrocarbon groups with 1 to 20 carbon atoms that may contain heteroatoms. Q+ represents either the strontium cation represented by formula (A2) or the monium cation represented by formula (A3). [Chemistry 2] In the formula, R11 to R15 independently represent hydrocarbon groups with 1 to 20 carbon atoms that may also contain heteroatoms. Furthermore, R11 and R12 may also bond to each other and form a ring together with the sulfur atoms they are bonded to. [Chemistry 3] In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. a1 is 0 or 1. a2 is an integer from 0 to 2. a3 is an integer satisfying 0 ≤ a3 ≤ 5 + 2a2 - a4. a4 is an integer from 1 to 3. R 21 is a halogen atom, or a 2-8 carbon saturated hydrocarbon carbonyloxy group that can be substituted by a halogen atom, or a 1-6 carbon saturated hydrocarbon group that can be substituted by a halogen atom, or a 1-6 carbon saturated hydrocarbon oxygen group that can be substituted by a halogen atom. A1 is a single bond or a saturated hydrocarbon group with 1 to 10 carbon atoms, and the -CH2- constituting the saturated hydrocarbon group can also be replaced by -O-. 2. The chemical amplification positive inhibitor composition as described in 1, wherein at least one of R1 to R5 is a group containing a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. 3. A chemically amplified positive inhibitor composition as in 1. or 2, wherein the repeating unit represented by formula (B1) is represented by formula (B1-1). [Chemistry 4] In the formula, RA and a4 are the same as those mentioned above. 4. A chemically amplified positive inhibitor composition as described in any of 1. to 3, wherein the aforementioned polymer further contains a repeating unit represented by the following formula (B2). [Chemistry 5] In the formula, RA is the same as that mentioned above. b1 is 0 or 1. b2 is an integer from 0 to 2. b3 is an integer satisfying 0 ≤ b3 ≤ 5 + 2b2 - b4. b4 is an integer from 1 to 3. b5 is 0 or 1. R 22 is a halogen atom, or a 2-8 carbon saturated hydrocarbon carbonyloxy group that can be replaced by a halogen atom, or a 1-6 carbon saturated hydrocarbon group that can be replaced by a halogen atom, or a 1-6 carbon saturated hydrocarbon oxygen group that can be replaced by a halogen atom. A2 is a single bond or a saturated hydrocarbon group with 1 to 10 carbon atoms, and the -CH2- constituting the saturated hydrocarbon group can also be replaced by -O-. When X is 1, it is an acid-labile group; when X is 2 or higher, it is a hydrogen atom or an acid-labile group, but at least one of them is an acid-labile group. 5. A chemically amplified positive inhibitor composition as described in any one of 1. to 4, wherein the aforementioned polymer further contains at least one repeating unit selected from the repeating unit represented by formula (B3), the repeating unit represented by formula (B4), and the repeating unit represented by formula (B5). [Chemistry 6] In the formula, RA is the same as that mentioned above. c and d are independent integers from 0 to 4. e1 is 0 or 1. e2 is an integer from 0 to 5. e3 is an integer from 0 to 2. R 23 and R 24 are, independently, a hydroxyl group, a halogen atom, a 2-8 carbon saturated hydrocarbon carbonyloxy group that can be substituted by a halogen atom, a 1-8 carbon saturated hydrocarbon group that can be substituted by a halogen atom, a 1-8 carbon saturated hydrocarbon carbonyloxy group that can be substituted by a halogen atom, or a 2-8 carbon saturated hydrocarbon carbonyloxy group that can be substituted by a halogen atom. R 25 is acetyl, a saturated hydrocarbon group with 1 to 20 carbon atoms, a saturated hydrocarbon oxy group with 1 to 20 carbon atoms, a saturated hydrocarbon carbonyl oxy group with 2 to 20 carbon atoms, a saturated hydrocarbon oxy hydrocarbon group with 2 to 20 carbon atoms, a saturated hydrocarbon thioalkyl group with 2 to 20 carbon atoms, a halogen atom, a nitro group, a cyano group, a sulfinyl group, or a sulfonyl group. A3 is a single bond or a saturated hydrocarbon group with 1 to 10 carbon atoms, and the -CH2- constituting the saturated hydrocarbon group can also be replaced by -O-. 6. A chemically amplified positive inhibitor composition as described in any one of 1. to 5, wherein the aforementioned polymer further contains at least one repeating unit selected from the following formulas (B6) to (B13). [Chemistry 7] In the formula, RB can be either a hydrogen atom or a methyl group. Z1 is a single bond, an aliphatic alkyl group with 1 to 6 carbon atoms, an alkyl phenyl group, an alkyl naphthyl group, or a combination thereof with 7 to 18 carbon atoms, -OZ11-, -C(=O)-OZ11- or -C(=O)-NH-Z11-, Z11 is an aliphatic alkyl group with 1 to 6 carbon atoms, an alkyl phenyl group, an alkyl naphthyl group, or a combination thereof with 7 to 18 carbon atoms, and may also contain a carbonyl group, an ester bond, an ether bond or a hydroxyl group. Z2 is a single bond or -Z21-C(=O)-O-, where Z21 is a hydrocarbon group with 1 to 20 carbon atoms that may also contain heteroatoms. Z 3 can be a single bond, methylene, ethyl, phenyl, fluorinated phenyl, phenyl substituted with trifluoromethyl, -OZ 31-, -C(=O)-OZ 31- or -C(=O)-NH-Z 31-, where Z 31 is an aliphatic phenyl group with 1 to 6 carbon atoms, phenyl, fluorinated phenyl, phenyl substituted with trifluoromethyl, or a group with 7 to 20 carbon atoms obtained by combining them, and may also contain a carbonyl group, ester bond, ether bond or hydroxyl group. Z4 is a single bond or may contain a heteroatom of 1 to 30 carbon atoms in a alkyl group. f1 and f2 are 0 or 1 independently, but when Z4 is a single bond, f1 and f2 are 0. R 31 to R 48 are each independently a hydrocarbon group with 1 to 20 carbon atoms, which may also contain heteroatoms. Furthermore, R 31 and R 32 may also bond to each other and form a ring together with the sulfur atoms they are bonded to, and R 33 and R 34, R 36 and R 37, or R 39 and R 40 may also bond to each other and form a ring together with the sulfur atoms they are bonded to. R HF represents a hydrogen atom or a trifluoromethyl group. Xa- is a non-nucleophilic relative ion. 7. The chemical amplification positive inhibitor composition of any one of 1. to 6, further comprising (D) polymer, including a repeating unit represented by formula (D1) and at least one repeating unit selected from formulas (D2) to (D5). [Chemistry 8] In the formula, RC can be independently represented by a hydrogen atom or a methyl group. RD can be independently represented by a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R 51 is a hydrogen atom, or a straight-chain or branched hydrocarbon group containing heteroatoms inserted between carbon-carbon bonds, consisting of 1 to 5 carbon atoms. R 52 is a straight-chain or branched hydrocarbon group with 1 to 5 carbon atoms that can also have a heteroatom inserted between carbon-carbon bonds. R53, R54, R56 and R57 are each independently a hydrogen atom or a saturated hydrocarbon group with 1 to 10 carbon atoms. R55, R58, R59 and R60 are independently hydrogen atoms, hydrocarbon groups with 1 to 15 carbon atoms, fluorinated hydrocarbon groups or acid-unstable groups, and when R55, R58, R59 and R60 are hydrocarbon groups or fluorinated hydrocarbon groups, ether bonds or carbonyl groups may be inserted between carbon-carbon bonds. k1 is an integer from 1 to 3. k2 is an integer satisfying 0 ≤ k2 ≤ 5 + 2k3 - k1. k3 is 0 or 1. m is an integer from 1 to 3. X 1 is a single bond, -C(=O)-O- or -C(=O)-NH-. X 2 is a hydrocarbon group with a carbon number of 1 to 20 and a valence of (m+1) or a fluorinated hydrocarbon group with a carbon number of 1 to 20 and a valence of (m+1). 8. Any of the chemical amplification positive inhibitor compositions in 1 to 7, further contains (E) organic solvents. 9. A chemically amplified positive resist composition as described in any of 1 to 8, which provides a resist film with an extinction coefficient (k value) of less than 0.01 for inspection light with a wavelength of 300 to 400 nm. 10. A method for forming a resist pattern, comprising the following steps: A resist film is formed on a substrate using a chemically amplified positive resist composition as described in any of 1.~9. The pattern was created by irradiating the aforementioned resist film with high-energy rays, and The resist film with the previously irradiated pattern was developed using an alkaline developer. 11. The resist pattern forming method as described in 10, wherein the aforementioned high-energy rays are EUV or EB. 12. The resist patterning method of 10 or 11, wherein the outermost surface of the aforementioned substrate is composed of a material comprising at least one selected from chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin. 13. The resist pattern forming method of any one of 10. to 12, wherein the aforementioned substrate is a blank photomask. 14. A blank photomask, comprising: The resist film is obtained from any one of the chemical amplification positive resist composition in 1 to 9. 15. As in 14, the blank photomask also has an antistatic film. [Effects of the Invention]

[0019] The chemically amplified positive resist composition of this invention utilizes the effect of the onium salt compound represented by formula (A1) to effectively control acid diffusion caused by exposure during pattern formation. When patterned by forming a resist film, it exhibits extremely high resolution and can obtain improved LER and CDU patterns. Furthermore, its high solubility in the solvent used for the resist composition prevents the aggregation of the acid diffusion control agent and suppresses defect formation. In addition, since it is not sensitive to short-wavelength inspection light (300-400 nm), it can also inspect minute defects using short-wavelength inspection light. Moreover, the repeating unit represented by formula (B1) not only exhibits good solubility in alkaline developer but also improves the adhesion to the substrate when forming the resist film.

[0020] The resist patterning method using the chemically amplified positive resist composition of the present invention can form patterns with high resolution and improved LER and CDU, suppress defects, and also perform inspection of small defects using short wavelengths. Therefore, it is applicable to microfabrication technology, especially EUV lithography and EB lithography. Simple Explanation of the Diagram

[0021] [Figure 1] is the 1H-NMR spectrum of compound QA obtained from Synthesis Example 1-1. Implementation

[0022] The present invention will now be described in detail. Furthermore, in the following description, depending on the structure represented by the chemical formula, there may be asymmetric carbons and possibly mirror-image isomers and non-mirror-image isomers; in such cases, these isomers are represented by a general formula. These isomers may be used individually or in mixtures.

[0023] [Chemical Amplification Positive Inhibitor Composition] The chemical amplification positive inhibitor composition of the present invention is characterized by containing: (A) a predetermined onium salt compound, (B) a base polymer comprising a predetermined polymer and (C) a photoacid generator.

[0024] [(A) Onium salt compound] (A) The onium salt compound of component (A1) is represented by the following formula (A1). [Chemistry 9]

[0025] In formula (A1), R1 to R5 are independently hydrogen atoms, halogen atoms, nitro groups, cyano groups, aldehyde groups, or hydrocarbon groups with 1 to 18 carbon atoms that may contain heteroatoms, -C(O)OR6, -C(O)R7, -OR8, -S(O)2R9, or -S(O)2N(R10)2. R6 and R7 are independently hydrocarbon groups with 1 to 19 carbon atoms that may contain heteroatoms. R8 and R9 are independently hydrocarbon groups with 1 to 20 carbon atoms that may contain heteroatoms. R10 is independently hydrogen atoms or hydrocarbon groups with 1 to 20 carbon atoms that may contain heteroatoms.

[0026] Halogen atoms represented by R1 to R5 can be listed as follows: fluorine atom, chlorine atom, bromine atom, iodine atom, etc.

[0027] R1 to R10 represent hydrocarbon groups that can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, secondary butyl, tertiary butyl, tertiary pentyl, n-pentyl, n-hexyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl; cyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norcamphenyl, tricyclo[5.2.1.0 2,6]decyl, adamantyl, and adamantylmethyl; alkenyl groups such as vinyl, allyl, propenyl, butenyl, and hexenyl; cyclic unsaturated aliphatic hydrocarbon groups such as cyclohexenyl; aryl groups with 6 to 20 carbon atoms such as phenyl, naphthyl, and anthracene; and groups obtained by combining them. Furthermore, some or all of the hydrogen atoms in the aforementioned hydrocarbon group can be replaced by a group containing heteroatoms such as oxygen atoms, sulfur atoms, nitrogen atoms, and halogen atoms. A portion of the -CH 2- group in the aforementioned hydrocarbon group can also be replaced by a group containing heteroatoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. As a result, it may contain hydroxyl groups, fluorine atoms, chlorine atoms, bromine atoms, iodine atoms, cyano groups, nitro groups, carbonyl groups, ether bonds, ester bonds, sulfonate bonds, carbonate bonds, lactone rings, sulfonolactone rings, carboxylic anhydrides (-C(=O)-OC(=O)-), haloalkyl groups, etc.

[0028] R1 to R5 should preferably be halogen atoms, alkyl groups with 1 to 6 carbon atoms, alkyl halogenates with 1 to 6 carbon atoms, hydroxyalkyl groups with 1 to 6 carbon atoms, alkyloxy groups with 1 to 6 carbon atoms, alkyloxy groups with 1 to 6 carbon atoms, etc.

[0029] Specific examples of the anions of onium salt compounds represented by formula (A1) are listed below, but are not limited to these. [Chemistry 10]

[0030] [Chemistry 11]

[0031] [Chemistry 12]

[0032] In formula (A1), Q+ is the strontium cation represented by formula (A2) or the monium cation represented by formula (A3). [Chemistry 13]

[0033] In formulas (A2) and (A3), R11 to R15 are each independently a hydrocarbon group with 1 to 20 carbon atoms, which may also contain heteroatoms. Furthermore, R11 and R12 may also bond to each other and form a ring together with the sulfur atoms they are bonded to.

[0034] The hydrocarbon groups represented by R11 to R15 can be saturated or unsaturated, and can be linear, branched, or cyclic. Specific examples can be listed and illustrated in the description of formula (A1) as hydrocarbon groups represented by R1 to R10. Aryl groups are particularly preferred for R11 to R15.

[0035] Furthermore, R11 and R12 can also bond to each other and form a ring together with the sulfur atoms they are bonded to. In this case, the aforementioned ring should preferably have the structure shown below. [Chemistry 14] In the formula, the dashed lines represent atomic bonds.

[0036] Specific examples of strontium cations represented by formula (A2) are listed below, but are not limited thereto. [Chemistry 15]

[0037] Specific examples of monazine cations represented by formula (A3) include: bis(4-methylphenyl)monazine, bis(4-ethylphenyl)monazine, bis(4-tributylphenyl)monazine, bis[4-(1,1-dimethylpropyl)phenyl]monazine, 4-methoxyphenylphenylmonazine, 4-tributylphenylphenylmonazine, 4-acryloxyphenylphenylmonazine, 4-methacryloxyphenylphenylmonazine, etc. Among them, bis(4-tributylphenyl)monazine is particularly preferred.

[0038] The specific structures of the aforementioned onium salts can be described by any combination of the specific examples of the aforementioned anions and specific examples of the aforementioned cations.

[0039] The onium salt compound represented by formula (A1) functions extremely effectively as an acid diffusion control agent when used in a chemically amplified positive resist composition. Furthermore, in this invention, the acid diffusion control agent refers to a material that prevents the acid generated by the photoacid generator in the chemically amplified positive resist composition from diffusing towards the unexposed area, thereby forming a desired pattern.

[0040] The acid diffusion control mechanism of the aforementioned onium salt compound is believed to be as follows. The acid that generates the photoacid generator in the inhibitor composition must be a strong acid in order to deprotect the acid-labile groups of the base polymer. For example, in EB lithography, unfluorinated sulfonic acid with the α-position of the sulfonate group is generally used. Here, if the photoacid generator coexists with the aforementioned onium salt compound in the inhibitor composition, the acid generated by the photoacid generator will be captured by the aforementioned onium salt compound, which will then become a phenolic compound. Considering that the aforementioned onium salt compound itself may photodecompose, the resulting product is a weakly acidic phenolic compound, which does not deprotect the acid-labile groups of the base polymer. It is speculated that this phenolic compound will thus function strongly as an acid diffusion control agent.

[0041] This acid diffusion control agent, also known as an onium salt quencher, generally tends to reduce the LER of the resist pattern compared to acid diffusion control agents using amine compounds. It is presumed that this is due to the repeated salt exchange between strong acid and the aforementioned onium salt compound. That is, the location where strong acid is generated at the end of the exposure differs from the location of the initial strong acid-generating onium salt. It is presumed that the cycle of acid generation and salt exchange caused by repeated light exposure averages out the acid generation points, and this homogenization effect reduces the LER of the resist pattern after development.

[0042] Since the onium salt compound represented by formula (A1) does not have absorption in the short wavelength region of 300-400 nm, the inspection of minute defects in the resist film of the chemically amplified positive resist composition of the present invention can be carried out using an inspection device that uses short-wavelength inspection light. Here, the wavelength of the inspection light used by the inspection device for confirming the aforementioned minute defects in the resist film can be 355 nm, but is not limited thereto.

[0043] In order to avoid photosensitivity caused by inspection light, the extinction coefficient (k value) of the resist film of the chemically amplified positive resist composition of the present invention is preferably 0.01 or less, more preferably 0.005 or less, and even more preferably 0.003 or less.

[0044] In formula (A1), at least one of R1 to R5 preferably contains a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. It is particularly preferred that at least one of R1 to R5 is a halogen atom, a halogenated alkyl group having 1 to 6 carbon atoms, or a halogenated alkyloxy group having 1 to 6 carbon atoms. This improves the solubility in organic solvents used as solvents for inhibiting the reaction, and even when a large amount of formula (A1) is added relative to the acid-generating agent to improve LER, aggregation will not occur, and defects can be prevented.

[0045] Furthermore, when forming an antistatic film on top of the resist film, at least one of R1 to R5 in the onium salt compound represented by formula (A1) preferably contains a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. It is particularly preferable that at least one of R1 to R5 is a halogen atom, a halogenated alkyl group having 1 to 6 carbon atoms, or a halogenated alkyloxy group having 1 to 6 carbon atoms. In this way, the onium salt compound represented by formula (A1) will disperse in the resist film without causing aggregation, thus effectively capturing the weak acids contained in the antistatic film. In addition, when at least one of R1 to R5 in formula (A1) contains a fluorine atom, the onium salt compound represented by formula (A1) will concentrate near the interface between the resist film and the antistatic film, which can very efficiently capture the weak acids contained in the antistatic film. As a result, the degradation of resist resolution caused by the antistatic film can be suppressed, and good resolution can still be obtained even when using an antistatic film.

[0046] In the chemical amplification positive inhibitor composition of this invention, the content of the onium salt compound represented by formula (A1) is preferably 0.1 to 100 parts by mass, and more preferably 1 to 80 parts by mass, relative to 80 parts by mass of the base polymer described later (B). If the content of the onium salt compound represented by formula (A1) is within the aforementioned range, it will function fully as an acid diffusion control agent, and there is no concern about performance degradation due to defects such as reduced sensitivity or insufficient solubility. The onium salt compound represented by formula (A1) can be used alone or in combination of two or more.

[0047] Furthermore, regarding the ratio of the photoacid generator to the onium salt compound represented by formula (A1), the ratio of the photoacid generator to the onium salt compound represented by formula (A1) should preferably be less than 4, and more preferably less than 3. If the aforementioned ratio is within the aforementioned range, acid diffusion can be sufficiently suppressed, and excellent resolution and CDU can be obtained.

[0048] Furthermore, the amount of photoacid generator added later should preferably be 5 parts by mass or more relative to 80 parts by mass of the polymer, and the total amount of the onium salt compound represented by formula (A1) and the photoacid generator added should preferably be 10 parts by mass or more relative to 80 parts by mass of the polymer. If the amount of addition meets these conditions, and the ratio of photoacid generator to onium salt compound represented by formula (A1) is less than the aforementioned 4, then the acid generation point of the exposed section can be sufficiently obtained, and acid diffusion can be suppressed, thus obtaining excellent resolution and CDU.

[0049] [(B) Basic Polymer] (B) The base polymer of the component contains a polymer containing a repeating unit (hereinafter also referred to as repeating unit B1) represented by the following formula (B1). [Chemistry 16]

[0050] In formula (B1), RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0051] In formula (B1), a1 is 0 or 1. a2 is an integer from 0 to 2, where 0 represents the benzene skeleton, 1 represents the naphthalene skeleton, and 2 represents the anthracene skeleton. a3 is an integer satisfying 0 ≤ a3 ≤ 5 + 2a2 - a4, and a4 is an integer from 1 to 3. When a2 is 0, it is preferable that a3 is an integer from 0 to 3 and a4 is an integer from 1 to 3. When a2 is 1 or 2, it is preferable that a3 is an integer from 0 to 4 and a4 is an integer from 1 to 3.

[0052] In formula (B1), R 21 can be a halogen atom, a 2-8 carbonyl carbonyl group that can be substituted with a halogen atom, a 1-6 carbonyl group that can be substituted with a halogen atom, or a 1-6 carbonyl carbonyl group that can be substituted with a halogen atom. The aforementioned saturated hydrocarbon group, as well as the saturated hydrocarbon carbonyl group and the saturated hydrocarbon group, can be linear, branched, or cyclic. Specific examples include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, and hexyl; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining them. If the number of carbon atoms is below the upper limit, the solubility in alkaline developing solutions is good. When a3 is 2 or more, each R 21 can be the same or different.

[0053] In formula (B1), A1 is a single bond or a saturated hydrocarbon group with 1 to 10 carbon atoms, and the -CH2- constituting the saturated hydrocarbon group can also be replaced by -O-. The aforementioned saturated hydrocarbon group can be any of the following: linear, branched, or cyclic; specific examples include: alkyl diyl 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 their structural isomers; cyclic saturated hydrocarbon groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining them. When the aforementioned saturated hydrocarbon group contains an ether bond, if a1 in formula (B1) is 1, it can be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position for ester oxygen. Furthermore, when a1 is 0, the atom bonded to the main chain is an ether oxygen, and a second ether bond can be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position for this ether oxygen. In addition, if the number of carbon atoms in the aforementioned saturated hydrocarbon group is 10 or less, sufficient solubility in alkaline developing solutions can be obtained, which is more ideal.

[0054] When a1 is 0 and A1 is a single bond, that is, when the aromatic ring is directly bonded to the polymer backbone (i.e., there is no linking group (-C(=O)-OA1-)), ideal examples of repeating unit B1 can be listed from units such as 3-hydroxystyrene, 4-hydroxystyrene, 5-hydroxy-2-vinylinderm, and 6-hydroxy-2-vinylinderm. From the perspective of achieving excellent CDU, repeating unit B1 should preferably be represented by the repeating unit of formula (B1-1). By containing repeating units represented by formula (B1-1), the solubility of the exposure area in the alkaline developer can be improved, and the dimensional errors caused by slight differences in the contact impact of the developer can be mitigated, thus achieving excellent CDU. [Chemistry 17] In the formula, RA and a4 are the same as those mentioned above.

[0055] Furthermore, when a1 is 1 (that is, has -C(=O)-OA 1- as a linking basis), ideal examples of repeating unit B1 can be listed as follows, but are not limited to these. [Chemistry 18] In the formula, RA is the same as that mentioned above.

[0056] The content of repeating unit B1 in all repeating units constituting the aforementioned polymer is preferably 10-95 mol%, and more preferably 40-90 mol%. However, it is also desirable that the polymer used in this invention, as described later, contains at least one of the repeating units represented by formula (B3) and formula (B4) that provide higher etch resistance, and that the unit has a phenolic hydroxyl group as a substituent, and that ratio also falls within the aforementioned range. Repeating unit B1 can be used alone or in combination of two or more.

[0057] In order to provide the characteristic that the exposed portion of the aforementioned polymer dissolves in alkaline aqueous solutions as a positive resist component, it is preferable to contain units with acidic functional groups protected by acid-indestructible groups (units protected by acid-indestructible groups and becoming alkali-soluble due to the action of acid). In this case, the acid-indestructible groups (protecting groups) in the aforementioned repeating units will undergo a deprotection reaction due to the action of acid, thus the aforementioned polymer will exhibit better solubility in alkaline developing solutions.

[0058] Such repeating units can be represented by the following formula (B2) (hereinafter also called repeating unit B2). [Chemistry 19]

[0059] In formula (B2), RA is the same as described above. b1 is 0 or 1. b2 is an integer from 0 to 2, where 0 represents the benzene skeleton, 1 represents the naphthalene skeleton, and 2 represents the anthracene skeleton. b3 is an integer satisfying 0 ≤ b3 ≤ 5 + 2b2 - b4. b4 is an integer from 1 to 3. b5 is 0 or 1. When b2 is 0, it is preferable that b3 is an integer from 0 to 3 and b4 is an integer from 1 to 3; when b2 is 1 or 2, it is preferable that b3 is an integer from 0 to 4 and b4 is an integer from 1 to 3.

[0060] In formula (B2), R22 can be a halogen atom, a 2-8 carbonyl carbonyl group that can be substituted by a halogen atom, a 1-6 carbonyl group that can be substituted by a halogen atom, or a 1-6 carbonyl carbonyl group that can be substituted by a halogen atom. The aforementioned saturated hydrocarbon group, as well as the saturated hydrocarbon carbonyl group and the saturated hydrocarbon group, can be linear, branched, or cyclic. Specific examples include: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, butyl, pentyl, and hexyl; cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and groups obtained by combining them. If the number of carbon atoms is below the upper limit, the solubility in alkaline developing solutions is good. When b3 is 2 or more, each R22 can be the same or different.

[0061] In formula (B2), A2 is a single bond or a saturated hydrocarbon group with 1 to 10 carbon atoms, and the -CH2- constituting the saturated hydrocarbon group can also be replaced by -O-. The aforementioned saturated hydrocarbon group can be any of the following: linear, branched, or cyclic. Specific examples include: alkyl diyl 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 their structural isomers; cyclic saturated hydrocarbon groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining them. When the aforementioned saturated hydrocarbon group contains an ether bond, if b1 in formula (B2) is 1, it can be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position for ester oxygen. Furthermore, when b1 is 0, the atom bonded to the main chain is an ether oxygen, and a second ether bond can be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position for this ether oxygen. In addition, if the number of carbon atoms in the aforementioned saturated hydrocarbon group is 10 or less, sufficient solubility in alkaline developing solution can be obtained, which is more ideal.

[0062] In formula (B2), X is an acid-labile group when b4 is 1, and a hydrogen atom or an acid-labile group when b4 is 2 or more, but at least one of them is an acid-labile group. That is, the repeating unit B2 is either a phenolic hydroxyl group bonded to the aromatic ring that is protected by an acid-labile group or a carboxyl group bonded to the aromatic ring that is protected by an acid-labile group. Such acid-labile groups can be used without particular restriction if they are those that are desorbed by acid and provide an acidic group in many known chemical amplification inhibitor compositions.

[0063] If the aforementioned acid-instable group is a tertiary saturated hydrocarbon group, even when the inhibitor film thickness is, for example, 10-100 nm and a fine pattern with a linewidth of less than 45 nm is formed, it will still provide a pattern with a small LER, which is ideal. Regarding the aforementioned tertiary saturated hydrocarbon group, in order to obtain the monomer for polymerization by distillation, it is preferable to have 4-18 carbon atoms. Furthermore, the groups bonded to the tertiary carbon atoms of the aforementioned tertiary saturated hydrocarbon group can be saturated hydrocarbon groups with 1-15 carbon atoms containing oxygen-containing functional groups such as ether bonds or carbonyl groups, and the aforementioned groups bonded to the tertiary carbon atoms can also bond to each other and form rings.

[0064] Specific examples of the aforementioned bonds to tertiary carbon atoms include: methyl, ethyl, propyl, adamantyl, norcamphenyl, tetrahydrofuran-2-yl, 7-oxanorcamphenyl-2-yl, cyclopentyl, 2-tetrahydrofuranyl, tricyclo[5.2.1.0 2,6]decyl, tetracyclo[4.4.0.1 2,5.1 7,10]dodecyl, and 3-sideoxy-1-cyclohexyl.

[0065] Furthermore, examples of tertiary saturated hydrocarbon groups having these as substituents include: tertiary butyl, tertiary pentyl, 1-ethyl-1-methylpropyl, 1,1-diethylpropyl, 1,1,2-trimethylpropyl, 1-adamantyl-1-methylethyl, 1-methyl-1-(2-norborneol)ethyl, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl, 1-methyl-1-(7-oxanorborneol-2-yl)ethyl, 1-methylcyclopentyl, 1 -Ethylcyclopentyl, 1-propylcyclopentyl, 1-isopropylcyclopentyl, 1-cyclopentylcyclopentyl, 1-cyclohexylcyclopentyl, 1-(2-tetrahydrofuranyl)cyclopentyl, 1-(7-oxanorbornen-2-yl)cyclopentyl, 1-methylcyclohexyl, 1-ethylcyclohexyl, 1-cyclopentylcyclohexyl, 1-cyclohexylcyclohexyl, 2-methyl-2-norbornenyl, 2-ethyl-2-norbornenyl, 8-methyl-8-tricyclo[5.2.1.0] [2,6]decyl, 8-ethyl-8-tricyclo[5.2.1.0 2,6]decyl, 3-methyl-3-tetracyclo[4.4.0.1 2,5.1 7,10]dodecyl, 3-ethyl-3-tetracyclo[4.4.0.1 2,5.1 7,10]dodecyl, 2-methyl-2-adamantyl, 2-ethyl-2-adamantyl, 1-methyl-3-sideoxy-1-cyclohexyl, 1-methyl-1-(tetrahydrofuran-2-yl)ethyl, 5-hydroxy-2-methyl-2-adamantyl, 5-hydroxy-2-ethyl-2-adamantyl, but not limited thereto.

[0066] Furthermore, the aforementioned acid-indestabilizing groups can be exemplified by groups represented by formula (B2-1). Groups represented by formula (B2-1) are commonly used as acid-indestabilizing groups, and are an ideal option for providing a relatively rectangular pattern at the interface between the pattern and the substrate. When X is a group represented by formula (B2-1), an acetal structure is formed. [Chemistry 20]

[0067] In formula (B2-1), RL1 is a hydrogen atom or a saturated hydrocarbon group with 1 to 10 carbon atoms. RL2 is a saturated hydrocarbon group with 1 to 30 carbon atoms. The aforementioned saturated hydrocarbon group can be any of the following: linear, branched, or cyclic.

[0068] The RL1 group is appropriately selected based on the sensitivity of the decomposable group to acids. For example, if the design aims to ensure relatively high stability while allowing decomposition with strong acids, a hydrogen atom is chosen; if the design aims for higher reactivity and greater sensitivity to pH changes, a straight-chain alkyl group is chosen. Although it also depends on the combination of acid-generating agents and basic compounds incorporated into the inhibitor composition, when the RL2 group has a larger terminal alkyl group and the design results in a large change in solubility due to decomposition, an RL1 group with a secondary carbon atom bonded to the acetal carbon is more ideal. Examples of RL1 groups with a secondary carbon atom bonded to the acetal carbon include isopropyl, secondary butyl, cyclopentyl, and cyclohexyl.

[0069] In the aforementioned acetal group, to obtain higher resolution, RL2 should preferably be a polycyclic alkyl group with 7 to 30 carbon atoms. Furthermore, when RL2 is a polycyclic alkyl group, a bond should preferably be formed between the secondary carbon atom constituting the ring structure and the acetal oxygen. Compared to bonding at the tertiary carbon atom, bonding at the secondary carbon atom of the ring structure results in a more stable polymer, exhibiting good storage stability in the formulated resist composition, and without degradation of resolution. Moreover, compared to bonding at the primary carbon atom after inserting a linear alkyl group with 1 or more carbon atoms, the polymer also exhibits a better glass transition temperature (Tg), and the resist pattern after development will not suffer from shape defects due to baking.

[0070] Ideal examples of the basis represented by equation (B2-1) can be listed below, but are not limited to these. In addition, R L1 in the following equation is the same as that mentioned above. [Chemistry 21]

[0071] Other acid-labile groups can also be replaced by phenolic hydroxyl groups with a hydrogen atom replaced by -CH₂COO- (a tertiary saturated hydrocarbon group). In this case, the aforementioned tertiary saturated hydrocarbon group can be the same as the tertiary saturated hydrocarbon group used for the protection of the aforementioned phenolic hydroxyl group.

[0072] The content of repeating unit B2 in all repeating units constituting the aforementioned polymer should preferably be 5-45 mol%. Repeating unit B2 can be used alone or in combination of two or more types.

[0073] The aforementioned polymer may further contain at least one of the repeating units selected from the following formula (B3) (hereinafter also referred to as repeating unit B3), the following formula (B4) (hereinafter also referred to as repeating unit B4), and the following formula (B5) (hereinafter also referred to as repeating unit B5). [Chemistry 22]

[0074] In equations (B3) and (B4), c and d are independent integers from 0 to 4.

[0075] In formulas (B3) and (B4), R23 and R24 are independently a hydroxyl group, a halogen atom, a 2-8 carbon-numbered saturated hydrocarbon carbonyloxy group that can be substituted by a halogen atom, a 1-8 carbon-numbered saturated hydrocarbon group that can be substituted by a halogen atom, a 1-8 carbon-numbered saturated hydrocarbon carbonyloxy group that can be substituted by a halogen atom, or a 2-8 carbon-numbered saturated hydrocarbon carbonyloxy group that can be substituted by a halogen atom. The aforementioned saturated hydrocarbon group, saturated hydrocarbon oxygen group, and saturated hydrocarbon carbonyloxy group can be any of the following: linear, branched, or cyclic. When c is 2 or more, each R23 can be the same or different. When d is 2 or more, each R24 can be the same or different.

[0076] In formula (B5), e1 is 0 or 1. e2 is an integer from 0 to 5. e3 is an integer from 0 to 2, and when it is 0, it represents the benzene skeleton, when it is 1, it represents the naphthalene skeleton, and when it is 2, it represents the anthracene skeleton. When e3 is 0, e2 should preferably be an integer from 0 to 3. When e3 is 1 or 2, e2 should preferably be an integer from 0 to 4.

[0077] In formula (B5), RA is the same as described above. R25 can be acetyl, a saturated hydrocarbon group with 1-20 carbon atoms, a saturated hydrocarbon oxy group with 1-20 carbon atoms, a saturated hydrocarbon carbonyl oxy group with 2-20 carbon atoms, a saturated hydrocarbon thioalkyl group with 2-20 carbon atoms, a halogen atom, a nitro group, a cyano group, a sulfinyl group, or a sulfonyl group. The aforementioned saturated hydrocarbon group, saturated hydrocarbon oxy group, saturated hydrocarbon carbonyl oxy group, saturated hydrocarbon oxyalkyl group, and saturated hydrocarbon thioalkyl group can be any of the following: linear, branched, or cyclic. When e2 is 2 or more, each R25 can be the same or different.

[0078] R 25 is preferably a halogen atom such as chlorine, bromine, or iodine; a saturated hydrocarbon group such as methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl, cyclohexyl, or their structural isomers; or a saturated hydrocarbon group such as methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, cyclopentoxy, cyclohexoxy, or their hydrocarbon structural isomers. Among these, methoxy and ethoxy are particularly preferred.

[0079] Furthermore, saturated hydrocarbon carbonyl oxy groups can be easily introduced through chemical modification even after polymer polymerization, and can be used to fine-tune the solubility of the base polymer in alkaline developers. Examples of such saturated hydrocarbon carbonyl oxy groups include: methyl carbonyl oxy, ethyl carbonyl oxy, propyl carbonyl oxy, butyl carbonyl oxy, pentyl carbonyl oxy, hexyl carbonyl oxy, cyclopentyl carbonyl oxy, cyclohexyl carbonyl oxy, benzoyl oxy, and their hydrocarbon structural isomers. If the carbon number is 20 or less, the effect of controlling / adjusting the solubility of the base polymer in alkaline developers (mainly the reduction effect) can be appropriately adjusted, and the generation of scum (development defects) can be suppressed.

[0080] Among the aforementioned ideal substituents, those that are particularly easy to prepare in monomer form and can be ideally used include: chlorine atom, bromine atom, iodine atom, methyl, ethyl, methoxy, etc.

[0081] In formula (B5), A3 is a single bond or a saturated alkyl group with 1 to 10 carbon atoms, and the -CH2- constituting the saturated alkyl group can also be replaced by -O-. The aforementioned saturated alkyl group can be any of the following: linear, branched, or cyclic. Specific examples include: alkyl diyl 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 their structural isomers; cyclic saturated alkyl groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; and groups obtained by combining them. When the aforementioned saturated alkyl group contains an ether bond, if e1 in formula (B5) is 1, it can be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position for ester oxygen. Furthermore, when e1 is 0, the atom bonded to the main chain is an ether oxygen, and a second ether bond can be inserted at any position except between the carbon atom at the α-position and the carbon atom at the β-position for this ether oxygen. In addition, if the number of carbon atoms in the aforementioned saturated hydrocarbon group is 10 or less, sufficient solubility in alkaline developing solution can be obtained, which is more ideal.

[0082] When e1 is 0 and A3 is a single bond, that is, when the aromatic ring is directly bonded to the main chain of the polymer (i.e., it does not have a linker group (-C(=O)-OA3-)), ideal examples of repeating unit B5 can be listed from units such as styrene, 4-chlorostyrene, 4-methylstyrene, 4-methoxystyrene, 4-bromostyrene, 4-ethoxystyrene, 2-hydroxypropylstyrene, 2-vinylnaphthalene, 3-vinylnaphthalene, etc.

[0083] Furthermore, when e1 is 1 (i.e., when -C(=O)-OA 3- is used as a linking basis), ideal examples of repeating unit B5 can be listed as follows, but are not limited to these. In addition, RA is the same as described above in the following formula. [Chemistry 23]

[0084] [Chemistry 24]

[0085] When at least one of the repeating units B3 to B5 is used as a constituent unit, in addition to obtaining the etching resistance of the aromatic ring, the effect of improved etching resistance or EB irradiation resistance during pattern inspection can also be obtained due to the additional ring structure of the main chain.

[0086] To achieve the effect of improving etching resistance, the content of repeating units B3 to B5 should preferably be 5 moles or more in all repeating units constituting the aforementioned polymer. Furthermore, the content of repeating units B3 to B5 in all repeating units constituting the aforementioned polymer should preferably be 35 moles or less, and more preferably 30 moles or less. If the amount introduced when there are no functional groups or when the functional groups are not any of them is 35 moles or less, there is no concern about the generation of development defects, which is therefore ideal. Repeating units B3 to B5 can be used alone or in combination of two or more.

[0087] In the aforementioned polymer, it is ideal to have repeating units B1, B2, and at least one of repeating units selected from B3 to B5 as constituent units, considering the viewpoint of achieving a good balance between high etch resistance and resolution. In this case, these repeating units should preferably contain 60 mol% or more, more preferably 70 mol% or more, and even more preferably 80 mol% or more in all repeating units.

[0088] The aforementioned polymer may further contain at least one of the repeating units selected from the following formula (B6) (hereinafter also referred to as repeating unit B6), the following formula (B7) (hereinafter also referred to as repeating unit B7), the following formula (B8) (hereinafter also referred to as repeating unit B8), the following formula (B9) (hereinafter also referred to as repeating unit B9), the following formula (B10) (hereinafter also referred to as repeating unit B10), the following formula (B11) (hereinafter also referred to as repeating unit B11), the following formula (B12) (hereinafter also referred to as repeating unit B12), and the following formula (B13) (hereinafter also referred to as repeating unit B13). In this case, acid diffusion can be effectively suppressed, and a pattern with improved resolution and reduced LER can be obtained. [Chemistry 25]

[0089] In formulas (B6) to (B13), RB is independently a hydrogen atom or a methyl group. Z1 is a single bond, an aliphatic alkyl group with 1 to 6 carbon atoms, an alkylphenyl group, an alkylnaphthyl group, or a combination thereof with 7 to 18 carbon atoms, -OZ11-, -C(=O)-OZ11-, or -C(=O)-NH-Z11-, Z11 is an aliphatic alkyl group with 1 to 6 carbon atoms, an alkylphenyl group, an alkylnaphthyl group, or a combination thereof with 7 to 18 carbon atoms, and may also contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z2 is a single bond or -Z21-C(=O)-O-, Z21 is an alkyl group with 1 to 20 carbon atoms, and may also contain heteroatoms. Z3 can be a single bond, methylene, ethyl, phenyl, fluorinated phenyl, trifluoromethyl-substituted phenyl, -OZ31-, -C(=O)-OZ31-, or -C(=O)-NH-Z31-, where Z31 is an aliphatic alkyl group with 1 to 6 carbon atoms, phenyl, fluorinated phenyl, trifluoromethyl-substituted phenyl, or a combination thereof with 7 to 20 carbon atoms, and may also contain a carbonyl group, ester bond, ether bond, or hydroxyl group. Z4 can be a single bond or a alkyl group with 1 to 30 carbon atoms containing heteroatoms. f1 and f2 are independently 0 or 1, but when Z4 is a single bond, f1 and f2 are 0.

[0090] In formulas (B7) and (B11), when Z2 is -Z21-C(=O)-O-, Z21 can also contain heteroatoms and extended hydrocarbon groups, as shown below, but not limited to these. [Chemistry 26] In the formula, the dashed lines represent atomic bonds.

[0091] In formulas (B7) and (B11), RHF is a hydrogen atom or a trifluoromethyl group. Specific examples of RHF being a hydrogen atom in repeating units B7 and B11 can be found in Japanese Patent Application Publication No. 2010-116550, and specific examples of RHF being a trifluoromethyl group can be found in Japanese Patent Application Publication No. 2010-77404. Repeating units B8 and B12 can be found in Japanese Patent Application Publication Nos. 2012-246265 and 2012-246426.

[0092] In formulas (B6) and (B10), Xa- represents a non-nucleophilic relative ion. Examples of non-nucleophilic relative ions represented by Xa- can be found in Japanese Patent Application Publication No. 2010-113209 and Japanese Patent Application Publication No. 2007-145797.

[0093] Ideal examples of anions providing monomers of repeating units B9 and B13 can be listed below, but are not limited thereto. [Chemistry 27]

[0094] [Chemistry 28]

[0095] In formulas (B6) to (B13), R31 to R48 are each independently a hydrocarbon group with 1 to 20 carbon atoms, which may also contain heteroatoms. The aforementioned hydrocarbon groups may be saturated or unsaturated, and may be linear, branched, or cyclic. Specific examples can be given as those exemplified in the description of formula (A1) as hydrocarbon groups represented by R1 to R10. Furthermore, some or all of the hydrogen atoms in the aforementioned hydrocarbon groups may be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, or halogen atoms, and a portion of the -CH2- group in the aforementioned hydrocarbon groups may also be replaced by groups containing heteroatoms such as oxygen, sulfur, or nitrogen atoms. As a result, the hydrocarbon groups may contain hydroxyl, fluorine, chlorine, bromine, iodine, cyano, nitro, carbonyl, ether, ester, sulfonate, carbonate, lactone ring, sulfonyl lactone ring, carboxylic anhydride (-C(=O)-OC(=O)-), haloalkyl, etc.

[0096] Furthermore, R31 and R32 can also bond to each other and form a ring together with the sulfur atoms they are bonded to. R33 and R34, R36 and R37, or R39 and R40 can also bond to each other and form a ring together with the sulfur atoms they are bonded to. Examples of the rings formed in this case are shown below. [Chemistry 29] In the formula, the dashed lines represent atomic bonds.

[0097] The specific structures of strontium cations in formulas (B7) to (B9) can be listed as follows, but are not limited to these. [Chemistry 30]

[0098] [Chemistry 31]

[0099] The specific structures of the molybdenum cations in formulas (B11) to (B13) can be listed as follows, but are not limited to these. [Chemistry 32]

[0100] [Chemistry 33]

[0101] Repeating units B6 to B13 are units that generate acid upon irradiation with high-energy rays. It is believed that the presence of these units in the polymer can appropriately suppress acid diffusion and obtain improved LER and CDU patterns. Furthermore, it is believed that the presence of these units in the polymer is effective in suppressing the phenomenon of acid evaporation from the exposed area and re-adhesion to the unexposed area during vacuum baking, improving LER and CDU, and reducing pattern defects caused by the suppression of undesirable deprotection reactions in the unexposed area. When repeating units B6 to B13 are included, their content should preferably be 0.5 to 30 mol% of all repeating units constituting the aforementioned polymer. Repeating units B6 to B13 can be used alone or in combination of two or more.

[0102] (B) The base polymer may also be a mixture of a polymer containing at least one of repeating units B6 to B13 in addition to repeating unit B1, and a polymer containing repeating unit B1 but not repeating units B6 to B13. In this case, the content of the polymer containing repeating unit B1 but not repeating units B6 to B13 is preferably 2 to 5000 parts by mass relative to 100 parts by mass of the polymer containing repeating units B6 to B13, and more preferably 10 to 1000 parts by mass.

[0103] Of all the repeating units in the aforementioned base polymer, the content of repeating units with aromatic ring skeletons should preferably be 65 mol% or more, preferably 85 mol% or more, and all units should preferably be repeating units with aromatic ring skeletons. This improves the polymerization uniformity of the polymer and the in-plane uniformity of the inhibitor film, resulting in excellent CDU.

[0104] As described in Patent Document 8, the aforementioned basic polymers are known to contain lactone functional groups. However, polymers with lactone functional groups suffer from reduced lipid solubility, which leads to decreased resistance to alkaline developers. Because of this property, which is a major cause of pattern shape deterioration and reduced CDU, the polymer in the chemical amplification positive resist composition of the present invention should preferably be lactone-free.

[0105] The aforementioned polymer can be synthesized by copolymerizing monomers with protecting groups as needed using known methods, followed by deprotection reactions as required. There are no particular limitations on the copolymerization reaction; free radical polymerization and anionic polymerization are preferred. For information on these methods, please refer to Japanese Patent Application Publication No. 2004-115630.

[0106] The weight-average molecular weight (Mw) of the aforementioned polymer is preferably between 1,000 and 50,000, and more preferably between 2,000 and 20,000. If Mw is above 1,000, there is no concern, as is conventional, about the formation of a rounded top of the pattern leading to reduced resolution and degradation of LER and CDU. On the other hand, if Mw is below 50,000, there is no concern about degradation of LER and CDU, especially when forming patterns with a linewidth of 100 nm or less. In addition, in this invention, Mw is a polystyrene-converted value determined by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as a solvent.

[0107] The molecular weight distribution (Mw / Mn) of the aforementioned polymer is 1.0~2.0, preferably a narrow dispersion of 1.0~1.8. With such a narrow dispersion, there will be no foreign matter generated on the pattern after development or the pattern shape will be deteriorated.

[0108] [(C) Photoacid Generator] The chemical amplification positive inhibitor composition of the present invention may also contain a photoacid generator (hereinafter also referred to as an additive photoacid generator) as component (C). There are no particular limitations on the aforementioned additive photoacid generator if it is a compound that generates acid upon irradiation by high-energy rays. Ideal photoacid generators include strontium salts, ferrous salts, sulfonyldiazomethane, N-sulfonoxyimide, oxime-O-sulfonate type acid generators, etc.

[0109] Specific examples of the aforementioned photoacid generators include: nonafluorobutane sulfonate, or the partially fluorinated sulfonate described in paragraphs

[0247] to

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

[0261] to

[0265] of Japanese Patent Application Publication No. 2013-101271, the partially fluorinated sulfonate described in paragraphs

[0122] to

[0142] of Japanese Patent Application Publication No. 2008-111103, and the photoacid generators described in paragraphs

[0080] to

[0081] of Japanese Patent Application Publication No. 2010-215608. Among these, aryl sulfonate type or alkyl sulfonate type photoacid generators are more ideal because they generate an acid with a strength suitable for deprotecting the acid unstable group of the repeating unit represented by formula (B2).

[0110] Such a photoacid generator is preferably a compound having a sulfonic acid anion with the structure shown below. Paired cations can be exemplified by the strontium cations in formulas (B7) to (B9) mentioned above, or by the ferronium cations in formulas (B11) to (B13) mentioned above. [Chemistry 34]

[0111] [Chemistry 35]

[0112] [Chemistry 36]

[0113] [Chemistry 37]

[0114] [Chemistry 38]

[0115] [Chemistry 39]

[0116] [Chemistry 40]

[0117] [Chemistry 41]

[0118] In the chemically amplified positive inhibitor composition of this invention, the content of the additive photoacid generator (C) relative to 80 parts by mass of the base polymer (B) is preferably 5 to 30 parts by mass, and more preferably 5 to 20 parts by mass. Furthermore, when the base polymer contains repeating units B6 to B13 (i.e., polymer-bonded acid generators), the addition of the additive photoacid generator can be omitted. The additive photoacid generator (C) can be used alone or in combination of two or more types.

[0119] [(D) Fluorinated polymers] In the chemical amplification positive resist composition of the present invention, in order to achieve high contrast, shield against chemical flare of acids during high-energy radiation irradiation, and prevent the mixing of acids from the antistatic film during the coating of the antistatic film material onto the resist film, and to suppress unintended pattern degradation, a fluorinated polymer may be included as component (D) comprising a repeating unit represented by formula (D1) (hereinafter also referred to as repeating unit D1) and repeating units selected from formulas (D2), (D3), (D4) and (D5) (hereinafter also referred to as repeating units D2, D3, D4 and D5, respectively). Since the aforementioned fluorinated polymer also possesses interfacial activity, it can prevent insoluble substances that may be generated during the development process from re-adhering to the substrate, thus also contributing to the treatment of development defects. [Chemistry 42]

[0120] In formulas (D1) to (D5), RC is independently a hydrogen atom or a methyl group. RD is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R51 is a hydrogen atom, or a straight-chain or branched hydrocarbon group with 1 to 5 carbon atoms, which may also have a heteroatom inserted between carbon-carbon bonds. R52 is a straight-chain or branched hydrocarbon group with 1 to 5 carbon atoms, which may also have a heteroatom inserted between carbon-carbon bonds. R53, R54, R56, and R57 are independently hydrogen atoms or saturated hydrocarbon groups with 1 to 10 carbon atoms. R55, R58, R59, and R60 are independently hydrogen atoms, hydrocarbon groups with 1 to 15 carbon atoms, fluorinated hydrocarbon groups, or acid-unstable groups. When R55, R58, R59, and R60 are hydrocarbon groups or fluorinated hydrocarbon groups, an ether bond or a carbonyl group may also be inserted between carbon-carbon bonds. k1 is an integer from 1 to 3. k2 is an integer satisfying 0 ≤ k2 ≤ 5 + 2k3 - k1. k3 is 0 or 1. m is an integer from 1 to 3. X1 is a single bond, -C(=O)-O- or -C(=O)-NH-. X2 is a hydrocarbon group with a carbon number of 1 to 20 and a valence of (m+1) or a fluorinated hydrocarbon group with a carbon number of 1 to 20 and a valence of (m+1).

[0121] R 51 and R 52 can represent hydrocarbon groups with 1 to 5 carbon atoms, including alkyl, alkenyl, and ynyl groups, preferably alkyl. Examples of the aforementioned alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, dibutyl, and n-pentyl. Furthermore, heteroatoms containing oxygen, sulfur, or nitrogen atoms can be inserted between the carbon-carbon bonds of these groups.

[0122] In formula (D1), -OR 51 should preferably be a hydrophilic group. In this case, R 51 should preferably be a hydrogen atom, an alkyl group with 1 to 5 carbon atoms with oxygen atoms inserted between carbon-carbon bonds, etc.

[0123] Repeating unit D1 can be listed as shown below, but is not limited to these. Additionally, in the following formula, RC is the same as described above. [Chemistry 43]

[0124] [Chemistry 44]

[0125] In repeating unit D1, X1 should preferably be -C(=O)-O- or -C(=O)-NH-. Furthermore, RC should preferably be methyl. The presence of a carbonyl group in X1 improves the ability to capture acids from the antistatic film. Also, if RC is methyl, it becomes a rigid polymer with a high glass transition temperature (Tg), thus inhibiting acid diffusion. Therefore, the stability of the resist film over time improves, and the resolution and pattern shape do not deteriorate.

[0126] In formulas (D2) and (D3), R53, R54, R56, and R57 represent saturated hydrocarbon groups with 1 to 10 carbon atoms, including: alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, secondary butyl, tertiary butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl; and cyclic saturated hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, adamantyl, and norbornel. Among these, saturated hydrocarbon groups with 1 to 6 carbon atoms are preferred.

[0127] In formulas (D2) to (D5), the hydrocarbon groups with 1 to 15 carbon atoms represented by R 55, R 58, R 59, and R 60 can be alkyl, alkenyl, alkynyl, etc., and preferably alkyl. In addition to the aforementioned alkyl groups, other alkyl groups can include n-undecyl, n-dodecyl, tridecyl, tetradecyl, pentadecyl, etc. Furthermore, fluorinated hydrocarbon groups can be groups in which one or all of the hydrogen atoms of the carbon atoms bonded to the aforementioned hydrocarbon groups are replaced by fluorine atoms.

[0128] X 2 represents hydrocarbon groups with a carbon number of 1 to 20 and a valence of (m+1) and fluorinated hydrocarbon groups with a carbon number of 1 to 20 and a valence of (m+1), which can be listed as groups obtained by further removing m hydrogen atoms from the aforementioned hydrocarbon groups or fluorinated hydrocarbon groups.

[0129] Specific examples of repeating units D2 to D5 can be listed below, but are not limited to these. Furthermore, in the following formula, RD is the same as described above. [Chemistry 45]

[0130] [Chemistry 46]

[0131] [Chemistry 47]

[0132] The content of repeating unit D1 in the total repeating units of the (D) fluorinated polymer is preferably 5-85 mol%, and more preferably 15-80 mol%. The content of repeating units D2-D5 in the total repeating units of the (D) fluorinated polymer is preferably 15-95 mol%, and more preferably 20-85 mol%. Repeating units D1-D5 can be used alone or in combination of two or more.

[0133] (D) Fluorinated polymers may also contain other repeating units besides the aforementioned repeating units. Examples of such repeating units include those described in paragraphs

[0046] to

[0078] of Japanese Patent Application Publication No. 2014-177407. (D) When fluorinated polymers contain other repeating units, their content in all repeating units should preferably be 50 mol% or less.

[0134] (D) Fluorinated polymers can be synthesized by copolymerizing monomers protected with protecting groups as needed using known methods, followed by deprotection reactions as required. There are no particular limitations on the copolymerization reaction; free radical polymerization and anionic polymerization are preferred. For information on these methods, please refer to Japanese Patent Application Publication No. 2004-115630.

[0135] (D) The Mw of fluorinated polymers should preferably be 2000~50000, and 3000~20000 is more preferred. If the Mw is less than 2000, it may sometimes promote acid diffusion, degrade resolution, or impair stability over time. If the Mw is too large, it may sometimes reduce the solubility in the solvent and cause coating defects. Also, (D) The Mw / Mn ratio of fluorinated polymers should preferably be 1.0~2.2, and 1.0~1.7 is more preferred.

[0136] In the chemical amplification positive inhibitor composition of the present invention, the content of (D) the fluorinated polymer relative to 80 parts by mass of (B) the base polymer is preferably 0.01 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass. (D) The fluorinated polymer can be used alone or in combination of two or more.

[0137] [(E) Organic solvents] The chemical amplification positive inhibitor composition of the present invention may also contain an organic solvent as component (E). There are no particular limitations on the organic solvent being capable of dissolving each component. Examples of such organic solvents include ketones such as cyclohexanone, cyclopentanone, methyl-2-n-pentyl ketone, and 2-heptanone as described in paragraphs

[0144] to

[0145] of Japanese Patent Application Publication No. 2008-111103; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and diacetone alcohol; and propylene glycol monomethyl ether and ethylene glycol monomethyl ether. Ethers such as dimethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tributyl acetate, tributyl propionate, and propylene glycol monotert-butyl ether acetate; lactones such as γ-butyrolactone; and mixed solvents thereof. When using the unstable acid group of an acetal system, a high-boiling-point alcohol solvent can be added to accelerate the deprotection reaction of the acetal. Specifically, diethylene glycol, propylene glycol, glycerol, 1,4-butanediol, and 1,3-butanediol can also be added.

[0138] Among these organic solvents, 1-ethoxy-2-propanol, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, cyclohexanone, ethyl lactate, γ-butyrolactone, and mixtures thereof are preferred.

[0139] In the chemical amplification positive inhibitor composition of the present invention, the content of (E) organic solvent relative to 80 parts by mass of (B) base polymer is preferably 200-10000 parts by mass, and more preferably 400-5000 parts by mass. (E) organic solvent can be used alone or in combination of two or more.

[0140] [(F) Basic compounds] For purposes such as pattern and shape correction, the chemically amplified positive resist composition of this invention may also contain (F) an alkaline compound as an acid diffusion control agent other than component (A). By adding an alkaline compound, acid diffusion can be effectively controlled, and even when a substrate made of a material containing chromium on its outermost surface is used as the substrate, the effect of acid generated within the resist film on the chromium-containing material can still be suppressed.

[0141] Regarding basic compounds, a variety are known, including: primary, secondary, or tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds with carboxyl groups, nitrogen-containing compounds with sulfonyl groups, nitrogen-containing compounds with hydroxyl groups, nitrogen-containing compounds with hydroxyphenyl groups, alcoholic nitrogen-containing compounds, amides, amides, carbamates, ammonium salts, etc. Specific examples of these are numerous and have been illustrated in Patent Document 9; essentially, all of them are usable. Among preferred examples are: tris(2-(methoxymethoxy)ethyl)amine, tris(2-(methoxymethoxy)ethyl)amine-N-oxide, dibutylaminobenzoic acid, α-line derivatives, imidazole derivatives, etc.

[0142] In the chemical amplification positive inhibitor composition of the present invention, the content of the (F) basic compound relative to 80 parts by mass of the (B) base polymer is preferably 0 to 10 parts by mass, and more preferably 0 to 5 parts by mass. The (F) basic compound can be used alone or in combination of two or more.

[0143] (G) Surfactants In order to improve the coatability of the chemically amplified positive resist composition of the present invention, it may also contain conventional surfactants. When using surfactants, as described in many examples in Japanese Patent Application Publication No. 2004-115630, various methods are known and can be selected by referring to them. In the chemically amplified positive resist composition of the present invention, the content of surfactant (G) is preferably 0 to 5 parts by mass relative to 80 parts by mass of the base polymer (B). Surfactant (G) can be used alone or in combination of two or more.

[0144] [Resistant Pattern Formation Method] The resist pattern forming method of the present invention includes the following steps: forming a resist film on a substrate using the aforementioned chemically amplified positive resist composition, irradiating the aforementioned resist film with a pattern using high-energy rays (i.e., exposing the aforementioned resist film with high-energy rays), and developing the aforementioned irradiated resist film with an alkaline developer.

[0145] The aforementioned substrate can be, for example, substrates used in integrated circuit manufacturing (Si, SiO, SiO2, SiN, SiON, TiN, WSi, BPSG, SOG, organic antireflective films, etc.) or substrates used in mask circuit manufacturing (Cr, CrO, CrON, MoSi2, Si, SiO, SiO2, SiON, SiN, SiONC, CoTa, NiTa, TaBN, SnO2, etc.). The aforementioned resist composition is coated onto the substrate using methods such as spin coating to achieve a film thickness of 0.03~2μm. The substrate is then pre-baked on a heated plate, preferably at 60~150°C for 1~20 minutes, more preferably at 80~140°C for 1~10 minutes, to form a resist film.

[0146] Then, the resist film is exposed and patterned using high-energy radiation. Examples of such high-energy radiation include: ultraviolet light, far-ultraviolet light, excimer laser light (KrF, ArF, etc.), EUV, X-rays, gamma rays, synchrotron radiation, and EB. In this invention, EUV or EB is preferably used for exposure.

[0147] When using ultraviolet light, far ultraviolet light, excimer laser light, EUV, X-rays, gamma rays, or synchrotron radiation to generate the aforementioned high-energy rays, an exposure dose of 1-500 mJ / cm², preferably 10-400 mJ / cm², is used to form the desired pattern. When using EB, irradiation is performed directly with an exposure dose of 1-500 μC / cm², preferably 10-400 μC / cm².

[0148] In addition to the usual exposure methods, exposure can also be achieved by wetting the mask and the resist film. In this case, a water-insoluble protective film can also be used.

[0149] Then, expose and bake on a heating plate at 60-150°C for 1-20 minutes, preferably 80-140°C for 1-10 minutes (PEB).

[0150] Subsequently, the desired pattern is formed on the substrate by using a developing solution containing 0.1-5% by mass, preferably 2-3% by mass, of an alkaline aqueous solution such as tetramethylammonium hydroxide (TMAH), and developing it using common methods such as dip, immersion, and spray for 0.1-3 minutes, preferably 0.5-2 minutes.

[0151] Furthermore, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation, especially for substrates with excellent resolution and capable of forming patterns with superior LER and CDU properties. Moreover, the chemically amplified positive resist composition of the present invention is particularly useful for pattern formation on substrates with materials on their surfaces that are prone to pattern peeling or breakage, as it readily achieves good adhesion of the resist pattern. Examples of such substrates include: substrates with a chromium film sputtered on their outermost surface, or chromium compounds containing one or more light elements selected from oxygen, nitrogen, and carbon atoms; substrates with a tantalum film sputtered on their outermost surface, or tantalum compounds containing one or more light elements selected from oxygen, nitrogen, and carbon atoms; and substrates with SiO₂ as their outermost layer. The chemically amplified positive resist composition of the present invention is particularly useful for pattern formation when using a blank photomask as the substrate.

[0152] If the resist patterning method of the present invention is used, even if a substrate (e.g., a blank photomask) is made of a material that easily affects the shape of the resist pattern, such as a material containing at least one of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin, is used on the outermost surface, the chemically amplified positive resist composition of the present invention can still form a high-resolution pattern with excellent LER and CDU by efficiently controlling acid diffusion at the substrate interface and by exposure.

[0153] The chemically amplified positive resist composition of the present invention can suppress the generation of defects, so even when forming tiny patterns, a pattern forming substrate with a small number of defects can still be obtained.

[0154] Furthermore, when using the chemically amplified positive resist composition of the present invention for pattern formation, since defect inspection can be performed at a short wavelength of less than 400 nm, minute defects can be detected. [Example]

[0155] The present invention will now be specifically described with reference to exemplary embodiments and comparative examples, but the present invention is not limited to the embodiments described below. Furthermore, the copolymer composition ratio is molar ratio, and Mw is the polystyrene conversion value determined by GPC. The apparatus used is as described below. • 1H-NMR: Manufactured by Nippon Electronics Co., Ltd., ECA-500

[0156] [1] Synthesis of acid diffusion control agents [Synthetic Example 1-1] Synthesis of Triphenylstrontium 3,5-Bis(trifluoromethyl)phenolate (QA) [Chemistry 48]

[0157] 50g of 3,5-bis(trifluoromethyl)phenol was added to 200g of pure water, and 34.8g of 25% sodium hydroxide aqueous solution was added to the solution. The mixture was stirred for 30 minutes. After stirring, 400g of dichloromethane and 648.5g of 10% aqueous solution of triphenylsilane chloride (a chlorinated compound) were added. The organic layer was separated and extracted, washed with water, and concentrated under reduced pressure. Methyl isobutyl ketone was added to the concentrated residue, and the mixture was concentrated under reduced pressure again. Hexane was added to the residue to carry out recrystallization. The resulting crystals were recovered and dried under vacuum to obtain triphenylsilane 3,5-bis(trifluoromethyl)phenol salt (QA) as the target compound (yield 100.8g, 94% yield). The NMR spectrum (1H-NMR / DMSO-d6) of compound QA is shown in Figure 1.

[0158] [Synthetic Examples 1-2, 1-3] Synthesis of Compounds QB and QC By changing the raw materials and chlorine compounds, the following compounds QB and QC were synthesized using the same method as in Synthesis Example 1-1. [Chemistry 49]

[0159] [2] Polymer Synthesis [Synthetic Example 2-1] Synthesis of Polymer A1 407.5 g of acetylacetonate, 42.5 g of acenaphthene, and 1275 g of toluene as a solvent were added to a 3 L flask. The reaction vessel was cooled to -70 °C under nitrogen atmosphere, and the process of degassing under reduced pressure and nitrogen blowing was repeated three times. After heating to room temperature, 34.7 g of 2,2'-azobis(2,4-dimethylpentanonitrile) (Fujifilm Wako Pure Chemicals Co., Ltd. V-65) as a polymerization initiator was added, and the temperature was raised to 55 °C, allowing the reaction to proceed for 40 hours. A mixed solvent of 970 g of methanol and 180 g of water was added dropwise to the reaction solution while stirring. After the addition was complete, the mixture was allowed to stand for 30 minutes to separate into two layers. The lower layer (polymer layer) was concentrated under reduced pressure, and then dissolved again in a mixed solvent of 0.45 L of methanol and 0.54 L of THF. 160 g of triethylamine and 30 g of water were added to this solution, and the deprotection reaction was carried out at 60 °C for 40 hours. The deprotection reaction solution was concentrated under reduced pressure. 548 g of methanol and 112 g of acetone were added to the concentrate to solubilize it. 990 g of hexane was added dropwise while stirring. After the addition was complete, the mixture was allowed to stand for 30 minutes to separate into two layers. 300 g of THF was added to the lower layer (polymer layer), and 1030 g of hexane was added dropwise while stirring. After 30 minutes, the lower layer (polymer layer) was concentrated under reduced pressure. The resulting polymer solution was neutralized with 82 g of acetic acid. After concentration, the solution was dissolved in 0.3 L of acetone, and then water was added to 10 L to precipitate the precipitate. The precipitate was then filtered and dried to obtain 280 g of white polymer. The obtained polymer, when analyzed by 1H-NMR and GPC, was found to have a copolymer composition of hydroxystyrene:acenaphthene = 89.3:10.7, Mw = 5000, and Mw / Mn = 1.63. In 100g of the obtained polymer, 50g of (2-methyl-1-propenyl) methyl ether was reacted under acidic conditions, followed by neutralization, liquid-liquid separation, and crystallization steps to obtain polymer A1. The yield was 125g.

[0160] [Synthetic Example 2-2] Synthesis of polymers A-2~A-7 and polymer P-1 By changing the raw material compounds used, polymers A-2 to A-7 and polymer P-1 were synthesized using the same method as in Synthesis Example 2-1.

[0161] The structures of polymers A-1 to A-6 are shown below. [Transformation 50]

[0162] The structure of polymer A-7 used in the comparative example is shown below. [Chemistry 51]

[0163] The structure of polymer P-1 is shown below. [Chemistry 52]

[0164] [3] Preparation of positive inhibitor composition [Examples 1-1 to 1-35, Comparative Examples 1-1 to 1-12] The components were dissolved in organic solvents according to the compositions shown in Tables 1 to 3 below, and the resulting solutions were filtered through UPE filters with a size of 0.02 μm to obtain chemically amplified positive inhibitor compositions (R-1 to R-35, CR-1 to CR-12).

[0165] In addition, the organic solvents listed in Tables 1-3 are PGMEA (propylene glycol monomethyl ether acetate), EL (ethyl lactate), and PGME (propylene glycol monomethyl ether).

[0166] The structures of the acid diffusion control agents QD and QE, photoacid generators PAG-A to PAG-C, and fluorinated polymers C-1 and C-2 used in the comparative examples are described in Tables 1 to 3 below. QD, QE: [Chemistry 53]

[0167] ･PAG-A~PAG-C: [Chemistry 54]

[0168] •C-1, C-2: [Chemistry 55]

[0169] [Table 1] inhibitor Composition Acid diffusion control agent (parts by weight) Polymer 1 (parts by weight) Polymer 2 (parts by weight) Photoacid generator (parts by weight) Fluorinated polymers (parts by weight) Solvent 1 (parts by weight) Solvent 2 (parts by weight) Solvent 3 (parts by weight) Example 1-1 R-1 QA (3.0) A-1 (80) - PAG-A (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-2 R-2 QA (5.0) A-1 (80) - PAG-A (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-3 R-3 QA (5.0) A-1 (80) - PAG-B (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-4 R-4 QA (5.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-5 R-5 QA (15.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-6 R-6 QA (25.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-7 R-7 QA (35.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-8 R-8 QA (15.0) A-1 (80) - PAG-C (10) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-9 R-9 QA (15.0) A-1 (80) - PAG-C (10) C-2 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-10 R-10 QA (15.0) A-2 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-11 R-11 QA (15.0) A-3 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-12 R-12 QA (15.0) A-4 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-13 R-13 QA (15.0) A-5 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-14 R-14 QA (15.0) A-6 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-15 R-15 QA (15.0) A-6 (80) - PAG-C (10) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-16 R-16 QA (15.0) A-3 (40) P-1 (40) - C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-17 R-17 QA (15.0) A-3 (40) P-1 (40) - C-2 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-18 R-18 QA (15.0) A-3 (40) P-1 (40) PAG-A (5) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-19 R-19 QA (15.0) A-3 (40) P-1 (40) PAG-C (5) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-20 R-20 QA (15.0) A-6 (40) P-1 (40) PAG-A (5) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-21 R-21 QA (15.0) A-6 (40) P-1 (40) PAG-C (5) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-22 R-22 QB (5.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-23 R-23 QB (15.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-24 R-24 QB (35.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-25 R-25 QB (15.0) A-1 (80) - PAG-C (10) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546)

[0170] [Table 2] inhibitor Composition Acid diffusion control agent (parts by weight) Polymer 1 (parts by weight) Polymer 2 (parts by weight) Photoacid generator (parts by weight) Fluorinated polymers (parts by weight) Solvent 1 (parts by weight) Solvent 2 (parts by weight) Solvent 3 (parts by weight) Example 1-26 R-26 QB (15.0) A-3 (80) - PAG-C (10) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-27 R-27 QB (15.0) A-6 (80) - PAG-A (10) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-28 R-28 QB (15.0) A-6 (80) - PAG-C (10) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-29 R-29 QB (15.0) A-3 (40) P-1 (40) PAG-A (5) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-30 R-30 QB (15.0) A-6 (40) P-1 (40) PAG-A (5) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-31 R-31 QB (15.0) A-6 (40) P-1 (40) PAG-C (5) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546) Example 1-32 R-32 QC (5.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-33 R-33 QC (15.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-34 R-34 QC (35.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Example 1-35 R-35 QC (15.0) A-6 (80) - PAG-C (10) C-1 (3) PGMEA (386) EL (1,932) PGME (1,546)

[0171] [Table 3] inhibitor Composition Acid diffusion control agent (parts by weight) Polymer 1 (parts by weight) Polymer 2 (parts by weight) Photoacid generator (parts by weight) Fluorinated polymers (parts by weight) Solvent 1 (parts by weight) Solvent 2 (parts by weight) Solvent 3 (parts by weight) Comparative example 1-1 CR-1 QD (5.0) A-1 (80) - PAG-A (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-2 CR-2 QD (5.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-3 CR-3 QD (15.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-4 CR-4 QD (25.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-5 CR-5 QD (35.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-6 CR-6 QE (5.0) A-1 (80) - PAG-C (5) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-7 CR-7 QE (15.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-8 CR-8 QE (25.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-9 CR-9 QE (35.0) A-1 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-10 CR-10 QA (5.0) A-7 (80) - PAG-C (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-11 CR-11 QA (2.0) A-1 (80) - PAG-A (10) - PGMEA (386) EL (1,932) PGME (1,546) Comparative example 1-12 CR-12 QA (2.0) A-1 (80) - PAG-A (5) - PGMEA (386) EL (1,932) PGME (1,546)

[0172] [4] Defect evaluation [Examples 2-1 to 2-35, Comparative Examples 2-1 to 2-9] Each chemically amplified positive inhibitor composition (R-1~R-35, CR-1~CR-9) was prepared and stirred for 8 hours. Afterwards, the dissolution of the inhibitor composition in the solvent was visually inspected.

[0173] The prepared resist compositions (R-1~R-35, CR-1~CR-9) were spin-coated onto a blank mask with a Cr film as the outermost layer using an ACT-M (Tokyo Powertech Co., Ltd.) spin-coated system. The films were then pre-baked at 110°C for 600 seconds on a heated plate to obtain a resist film with a thickness of 80 nm. A full-scale pattern was then created using an electron beam lithography (EBM-5000plus, NuFlare Technology Co., Ltd., accelerating voltage 50 kV) system, followed by PEB exposure at 110°C for 600 seconds. Development was then performed using a 2.38% (w / w) TMAH aqueous solution, and the development residue was evaluated using a mask defect inspection device (Lasertec Co., Ltd., M9650). The results are shown in Tables 4 and 5.

[0174] [Table 4] inhibitor composition Solvent solubility Visual inspection Number of defects Example 2-1 R-1 Dissolve 118 Example 2-2 R-2 Dissolve 120 Example 2-3 R-3 Dissolve 132 Examples 2-4 R-4 Dissolve 128 Examples 2-5 R-5 Dissolve 132 Examples 2-6 R-6 Dissolve 135 Examples 2-7 R-7 Dissolve 135 Examples 2-8 R-8 Dissolve 120 Examples 2-9 R-9 Dissolve 125 Example 2-10 R-10 Dissolve 138 Example 2-11 R-11 Dissolve 137 Example 2-12 R-12 Dissolve 134 Example 2-13 R-13 Dissolve 135 Example 2-14 R-14 Dissolve 134 Example 2-15 R-15 Dissolve 127 Example 2-16 R-16 Dissolve 129 Example 2-17 R-17 Dissolve 135 Example 2-18 R-18 Dissolve 129 Example 2-19 R-19 Dissolve 130 Example 2-20 R-20 Dissolve 129 Example 2-21 R-21 Dissolve 128 Example 2-22 R-22 Dissolve 126 Example 2-23 R-23 Dissolve 129 Example 2-24 R-24 Dissolve 133 Example 2-25 R-25 Dissolve 125 Example 2-26 R-26 Dissolve 128 Example 2-27 R-27 Dissolve 128 Example 2-28 R-28 Dissolve 127 Example 2-29 R-29 Dissolve 129 Examples 2-30 R-30 Dissolve 128 Example 2-31 R-31 Dissolve 129 Example 2-32 R-32 Dissolve 144 Example 2-33 R-33 Dissolve 160 Examples 2-34 R-34 Insoluble - Example 2-35 R-35 Dissolve 155

[0175] [Table 5] inhibitor composition Solvent solubility Visual inspection Number of defects Comparative Example 2-1 CR-1 Dissolve 210 Comparative Example 2-2 CR-2 Dissolve 206 Comparative Examples 2-3 CR-3 Dissolve 334 Comparative Examples 2-4 CR-4 Dissolve 560 Comparative Examples 2-5 CR-5 Insoluble - Comparative Examples 2-6 CR-6 Dissolve 220 Comparative Examples 2-7 CR-7 Dissolve 556 Comparative Examples 2-8 CR-8 Dissolve 945 Comparative Examples 2-9 CR-9 Insoluble -

[0176] The chemically amplified positive inhibitor compositions (R-1 to R-35) of the present invention containing onium salt compounds represented by formula (A1) all exhibited better defect reduction performance than the inhibitor compositions (CR-1 to CR-9) of the comparative examples. Furthermore, among the onium salt compounds represented by formula (A1), no increase in the number of defects was observed for QA and QB, which contain halogen atoms, even when the addition amount was increased to 35 parts by mass. However, for QC to QE, it was observed that with increasing addition amount, aggregate formation, an increase in the number of defects, or insolubility occurred.

[0177] [5] EB Microfilm Review [Examples 3-1 to 3-34, Comparative Examples 3-1 to 3-10] Each chemically amplified positive resist composition was spin-coated onto a 152 mm² blank mask with a Cr film as the outermost surface using an ACT-M spin coater. The mask was then pre-baked at 110°C for 600 seconds on a heated plate to obtain a resist film with a thickness of 80 nm. Next, exposure was performed using an electron beam lithography apparatus (EBM-5000plus, NuFlare Technology, 50 kV accelerating voltage), followed by PEB exposure at 110°C for 600 seconds, and then development with a 2.38% (w / w) TMAH aqueous solution to obtain a positive pattern.

[0178] The obtained resist patterns were evaluated as follows. The patterned blank mask was observed using an overhead SEM (scanning electron microscope). The optimal exposure (μC / cm²) was determined by resolving the 1:1 line-to-spacing (LS) at 200 nm using a 1:1 ratio. The smallest dimension within this 1:1 ratio of the 200 nm LS exposure was defined as the resolution (limiting resolution). Edge detection was performed at 80 points along the edges of each of the 32 lines of the 200 nm LS pattern using SEM, and the deviation (standard deviation, σ) was calculated as three times the value of the deviation (3σ) as the LER (nm). Furthermore, the dimensions at 144 locations within the blank substrate were measured for the 200 nm LS pattern obtained with the optimal exposure. The result was divided by three times the standard deviation (σ) as the CDU. A smaller CDU value indicates a better LS pattern. The results are shown in Tables 6 and 7.

[0179] [Table 6] inhibitor composition Optimal exposure (μC / cm 2) Limiting resolution (nm) LER (nm) CDU (nm) Example 3-1 R-1 27 37 4.0 2.6 Example 3-2 R-2 46 37 3.7 2.4 Example 3-3 R-3 48 37 3.8 2.4 Examples 3-4 R-4 51 37 3.9 2.4 Examples 3-5 R-5 102 37 3.2 2.1 Examples 3-6 R-6 155 35 2.4 1.5 Examples 3-7 R-7 210 32 2.1 1.3 Examples 3-8 R-8 99 37 3.1 2.1 Examples 3-9 R-9 100 37 3.2 2.1 Examples 3-10 R-10 101 37 3.3 2.2 Example 3-11 R-11 102 37 3.2 2.1 Example 3-12 R-12 115 37 3.1 2.1 Example 3-13 R-13 99 37 3.0 2.0 Example 3-14 R-14 99 37 2.9 1.9 Example 3-15 R-15 97 37 2.9 1.9 Example 3-16 R-16 90 37 3.0 2.0 Example 3-17 R-17 94 37 2.8 1.8 Example 3-18 R-18 89 35 2.7 1.8 Example 3-19 R-19 90 32 2.6 1.7 Example 3-20 R-20 88 35 2.6 1.8 Example 3-21 R-21 89 32 2.5 1.6 Example 3-22 R-22 48 35 3.9 2.5 Example 3-23 R-23 98 35 3.3 2.2 Example 3-24 R-24 201 32 2.2 1.4 Example 3-25 R-25 97 35 3.2 2.1 Example 3-26 R-26 96 37 3.1 2.1 Example 3-27 R-27 93 37 3.4 2.3 Example 3-28 R-28 95 35 3.1 2.0 Example 3-29 R-29 88 35 2.9 1.9 Examples 3-30 R-30 87 35 2.8 1.9 Example 3-31 R-31 92 32 2.7 1.8 Example 3-32 R-32 58 37 3.9 2.6 Example 3-33 R-33 118 37 3.6 2.4 Examples 3-34 R-35 114 37 3.5 2.4

[0180] [Table 7] inhibitor composition Optimal exposure (μC / cm 2) Limiting resolution (nm) LER (nm) CDU (nm) Comparative Example 3-1 CR-1 61 45 5.1 3.8 Comparative Example 3-2 CR-2 64 40 4.9 3.6 Comparative Example 3-3 CR-3 121 40 4.6 3.4 Comparative Examples 3-4 CR-4 168 40 4.5 3.1 Comparative Examples 3-5 CR-6 45 50 5.4 4.0 Comparative Examples 3-6 CR-7 91 45 5.1 3.7 Comparative Examples 3-7 CR-8 142 45 4.9 3.3 Comparative Examples 3-8 CR-10 49 40 5.4 4.2 Comparative Examples 3-9 CR-11 18 45 6.5 4.6 Comparative Example 3-10 CR-12 32 45 6.8 4.8

[0181] The chemically amplified positive inhibitor composition of the present invention containing onium salt compounds represented by formula (A1) exhibits better resolution than the inhibitor composition of the comparative examples, and LER and CDU also show good values.

[0182] When using onium salt compounds represented by formula (A1), such as QA and QB, at least one compound containing a fluorine atom, chlorine atom, bromine atom or iodine atom is used. Due to its high solubility in organic solvents, even if a large amount of this compound is added, it will not agglomerate, and excellent LER and CDU are achieved as shown in Examples 3-7 and 3-24.

[0183] The resist composition (CR-10) containing the A-7 polymer with a lactone backbone has reduced developer resistance due to decreased lipid solubility, resulting in deteriorated pattern shape. As shown in Comparative Examples 3-8, it is inferior to the chemically amplified positive resist composition of the present invention in terms of resolution, LER, and CDU.

[0184] The photoacid generator, with a content of 4 or more of the onium salt compound represented by formula (A1) in the inhibitor composition (CR-11), cannot adequately suppress acid diffusion. Therefore, as in Comparative Examples 3-9, it results in poorer resolution, LER, and CDU compared to the chemically amplified positive inhibitor composition of the present invention.

[0185] The resist composition (CR-12) in which the total amount of photoacid generator and onium salt compound represented by formula (A1) is less than 10 parts by mass cannot adequately obtain the acid generation point of the exposed part and cannot adequately suppress acid diffusion. Therefore, as in Comparative Examples 3-10, it results in poor resolution, LER and CDU compared to the chemical amplification positive resist composition of the present invention.

[0186] [6] Determination of extinction coefficient (k value) [Examples 4-1 to 4-9, Comparative Examples 4-1 to 4-3] The chemically amplified positive resist compositions shown in Table 8 were spin-coated onto a silicon wafer to obtain an evaluation substrate with a film thickness of 100 nm. The extinction coefficients (k-values) of the prepared substrates were measured using a VUV-VASE (manufactured by JA Woollam) when irradiated with light at wavelengths of 400 nm, 355 nm, 330 nm, and 300 nm. To prevent photosensitization of the resist film due to irradiation by inspection light, a k-value of 0.01 or less, and preferably 0.003 or less, was preferred. The results are shown in Table 8.

[0187] [Table 8] inhibitor composition k-value (400nm) k-value (355nm) k-value (330nm) k-value (300nm) Example 4-1 R-4 0.001 0.001 0.001 0.003 Example 4-2 R-5 0.001 0.002 0.002 0.004 Example 4-3 R-6 0.001 0.002 0.002 0.004 Example 4-4 R-7 0.001 0.002 0.002 0.006 Examples 4-5 R-22 0.001 0.001 0.001 0.004 Examples 4-6 R-23 0.001 0.002 0.002 0.005 Examples 4-7 R-24 0.001 0.002 0.002 0.006 Examples 4-8 R-32 0.001 0.001 0.001 0.005 Examples 4-9 R-33 0.001 0.002 0.002 0.008 Comparative Example 4-1 CR-2 0.011 0.011 0.011 0.035 Comparative Example 4-2 CR-3 0.011 0.012 0.013 0.038 Comparative Example 4-3 CR-4 0.012 0.015 0.017 0.042

[0188] The onium salt compound represented by formula (A1) exhibits a good k value of less than 0.01 at any wavelength, and an excellent k value of less than 0.003 at wavelengths of 400 nm, 355 nm, and 330 nm. On the other hand, the comparative example exhibits a k value of more than 0.01 at any wavelength, which exposes the resist film to light.

[0189] [7] Evaluation of EB lithography during antistatic film coating [Examples 5-1 to 5-9, Comparative Examples 5-1 to 5-5] The chemically amplified positive resist compositions shown in Table 9 were spin-coated onto a 152 mm square blank mask with a Cr film as the outermost surface using an ACT-M spin coater (manufactured by Tokyo Power Technology Co., Ltd.). The mask was then pre-baked at 110°C for 600 seconds on a heated plate to obtain a resist film with a thickness of 80 nm. A conductive polymer composition was then spin-coated onto the resist film and pre-baked at 70°C for 600 seconds on a heated plate to obtain an antistatic film with a thickness of 15 nm. The film was then exposed using an electron beam lithography apparatus (EBM-5000plus manufactured by NuFlare Technology Co., Ltd., accelerating voltage 50 kV), subjected to PEB at 110°C for 600 seconds, and developed with a 2.38% (w / w) TMAH aqueous solution to obtain a positive pattern.

[0190] The obtained resist patterns were evaluated as follows. The patterned blank mask was observed using an overhead SEM (scanning electron microscope). The optimal exposure (μC / cm²) was determined by resolving the 1:1 line-to-spacing (LS) at 200 nm using a 1:1 ratio. The smallest dimension among the 1:1 LS exposures at 200 nm was defined as the resolution (limiting resolution). The results are shown in Table 9.

[0191] [Table 9] inhibitor composition Optimal exposure (μC / cm 2) Limiting resolution (nm) Example 5-1 R-4 50 37 Example 5-2 R-5 100 37 Example 5-3 R-6 153 35 Example 5-4 R-7 207 32 Example 5-5 R-22 47 37 Examples 5-6 R-23 96 37 Examples 5-7 R-24 199 35 Examples 5-8 R-32 54 40 Examples 5-9 R-33 110 40 Comparative Example 5-1 CR-2 58 45 Comparative Example 5-2 CR-3 114 45 Comparative Example 5-3 CR-4 160 45 Comparative Example 5-4 CR-6 40 70 Comparative Example 5-5 CR-7 82 60

[0192] The chemically amplified positive resist composition of the present invention, containing halogen atoms QA or QB in the onium salt compound represented by formula (A1), exhibits excellent resolution even when coated with an antistatic film. On the other hand, resist compositions containing QC or QD exhibit good resolution, while resist compositions containing QE exhibit poor resolution. This is believed to be a result of an undesirable reaction caused by the slight deprotection of the protecting groups in the base polymer in the unexposed area due to the presence of weak acids in the antistatic film. Compounds QA to QD, due to their high basicity and structure that easily captures acids, are less likely to cause the aforementioned undesirable reaction. Furthermore, compound QA, containing fluorine atoms, can concentrate near the interface with the antistatic film coated on top of the resist film, thus effectively capturing weak acids in the antistatic film and achieving excellent resolution. Furthermore, because compound QB contains iodine atoms, it does not cause aggregation in the resistive film and has high uniformity of dispersion. Therefore, it can effectively capture weak acids in the antistatic film and obtain excellent resolution.

[0193] As explained above, using the chemically amplified positive resist composition of this invention can produce patterns with extremely high resolution, good LER and CDU, and few defects. Furthermore, due to its non-sensitivity to short-wavelength light, even minute defects can be detected using defect inspection employing short-wavelength light sources. The resist patterning method using the chemically amplified positive resist composition of this invention is useful in semiconductor device manufacturing, particularly in photolithography during the processing of blank photomasks.

[0194] none

Claims

1. A chemically amplified positive inhibitor composition comprising: (A) an onium salt compound represented by formula (A1); (B) a base polymer comprising repeating units represented by formula (B1) and repeating units represented by formula (B2), further comprising at least one repeating unit selected from formula (B3), formula (B4), and formula (B5), and a polymer that decomposes under the action of acid and increases its solubility in alkaline developing solution, but does not comprise a polymer comprising repeating units having a lactone ring; (C) a photoacid generator; and (D) a polymer comprising repeating units represented by formula (D1) and at least one repeating unit selected from formulas (D2) to (D5); wherein the content of repeating units having an aromatic ring skeleton in all repeating units of the polymer comprised in the base polymer is 65 mol% or more. Based on parts by mass, the content ratio of the photoacid generator to the onium salt compound represented by formula (A1) is less than 4, the content of the photoacid generator is more than 5 parts by mass relative to 80 parts by mass of the polymer, and the total content of the onium salt compound represented by formula (A1) and the photoacid generator is more than 10 parts by mass relative to 80 parts by mass of the polymer. In the formula, R1~R5 are independently hydrogen atoms, halogen atoms, nitro groups, cyano groups, aldehyde groups, or hydrocarbon groups with 1~18 carbon atoms containing heteroatoms, -C(O)OR6, -C(O)R7, -OR8, -S(O)2R9 or -S(O)2N(R10)2; R6 and R7 are independently hydrocarbon groups with 1~19 carbon atoms containing heteroatoms; R8 and R9 are independently hydrocarbon groups with 1~20 carbon atoms containing heteroatoms; R10 is independently hydrogen atoms or hydrocarbon groups with 1~20 carbon atoms containing heteroatoms; Q+ is a strontium cation represented by formula (A2) or a monium cation represented by formula (A3); In the formula, R11~R15 are independently hydrocarbon groups with 1~20 carbon atoms containing heteroatoms; Furthermore, R11 and R12 can also be bonded to each other and form a ring together with the sulfur atoms they are bonded to; In the formula, RA is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; a1 is 0 or 1; a2 is an integer from 0 to 2; a3 is an integer satisfying 0 ≤ a3 ≤ 5 + 2a2 - a4; a4 is an integer from 1 to 3; R21 is a halogen atom, a 2-8 carbon saturated hydrocarbon carbonyl group that can be substituted by a halogen atom, a 1-6 carbon saturated hydrocarbon group that can be substituted by a halogen atom, or a 1-6 carbon saturated hydrocarbon group that can be substituted by a halogen atom; A1 is a single bond or a 1-10 carbon saturated hydrocarbon group, and the -CH2- constituting the saturated hydrocarbon group can also be substituted by -O-; In the formula, RA is the same as above; b1 is 0 or 1; b2 is an integer from 0 to 2; b3 is an integer satisfying 0 ≤ b3 ≤ 5 + 2b2 - b4; b4 is an integer from 1 to 3; b5 is 0 or 1;R22 is a halogen atom, a 2-8 carbon saturated hydrocarbon carbonyl group that can be substituted by a halogen atom, a 1-6 carbon saturated hydrocarbon group that can be substituted by a halogen atom, or a 1-6 carbon saturated hydrocarbon oxygen group that can be substituted by a halogen atom; A2 is a single bond or a 1-10 carbon saturated hydrocarbon group, and the -CH2- constituting the saturated hydrocarbon group can also be substituted by -O-; X is an acid-unstable group when b4 is 1, and a hydrogen atom or an acid-unstable group when b4 is 2 or more, but at least one is an acid-unstable group; In the formula, RA is the same as above; c and d are independent integers from 0 to 4; e1 is 0 or 1; e2 is an integer from 0 to 5; e3 is an integer from 0 to 2; R23 and R24 are independently hydroxyl groups, halogen atoms, 2-8 carbonyl carbonyl groups that can be substituted with halogen atoms, 1-8 carbonyl groups that can be substituted with halogen atoms, 1-8 carbonyl groups that can be substituted with halogen atoms, or 2-8 carbonyl carbonyl groups that can be substituted with halogen atoms; R25 is acetyl, 1-20 carbonyl groups, 1-20 carbonyl carbonyl groups, 2-20 carbonyl carbonyl groups, 2-20 carbonyl oxyalkyl groups, 2-20 carbonyl thioalkyl groups, halogen atoms, nitro groups, cyano groups, sulfinyl groups, or sulfonyl groups; A3 is a single bond or a 1-10 carbonyl carbonyl group, and the -CH2- group constituting the saturated carbonyl group can also be substituted with -O-; In the formula, RC are independently hydrogen atoms or methyl groups; RD is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; R51 is a hydrogen atom, or a straight-chain or branched hydrocarbon group with 1 to 5 carbon atoms that may have a heteroatom inserted between carbon-carbon bonds; R52 is a straight-chain or branched hydrocarbon group with 1 to 5 carbon atoms that may have a heteroatom inserted between carbon-carbon bonds; R53, R54, R56, and R57 are independently hydrogen atoms or saturated hydrocarbon groups with 1 to 10 carbon atoms; R55, R58, R59, and R60 are independently hydrogen atoms, hydrocarbon groups with 1 to 15 carbon atoms, fluorinated hydrocarbon groups, or acid-unstable groups, and when R55, R58, R59, and R60 are hydrocarbon groups or fluorinated hydrocarbon groups, an ether bond or a carbonyl group may also be inserted between carbon-carbon bonds; k1 is an integer from 1 to 3; k2 is an integer satisfying 0 ≤ k2 ≤ 5 + 2k3 - k1; k3 is 0 or 1; m is an integer from 1 to 3; X1 is a single bond, -C(=O)-O-, or -C(=O)-NH-; X2 is a hydrocarbon group with a carbon number of 1 to 20 and a valence of (m+1) or a fluorinated hydrocarbon group with a carbon number of 1 to 20 and a valence of (m+1).

2. The chemical amplification positive inhibitor composition as claimed in claim 1, wherein, At least one of R1 to R5 is a base containing a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

3. As in claim 1, the chemical amplification positive inhibitor composition, wherein, The repeating unit represented by equation (B1) is represented by the following equation (B1-1); where RA and a4 are the same as those mentioned above.

4. The chemical amplification positive inhibitor composition as described in claim 1, wherein, The polymer further contains at least one repeating unit selected from the following formulas (B6) to (B13); wherein RB is independently a hydrogen atom or a methyl group; Z1 is a single bond, an aliphatic alkyl group with 1 to 6 carbon atoms, an alkyl phenyl group, an alkyl naphthyl group, or a group with 7 to 18 carbon atoms obtained by combining them, -O-Z11-, -C(=O)-O-Z11- or -C(=O)-NH-Z11-, Z11 is an aliphatic alkyl group with 1 to 6 carbon atoms, an alkyl phenyl group, an alkyl naphthyl group, or a group with 7 to 18 carbon atoms obtained by combining them, and may also contain a carbonyl group, an ester bond, an ether bond or a hydroxyl group; Z2 is a single bond or -Z21-C(=O)-O-, Z21 is an alkyl group with 1 to 20 carbon atoms that may also contain heteroatoms; Z3 can be a single bond, methylene, ethyl, phenyl, fluorinated phenyl, trifluoromethyl-substituted phenyl, -O-Z31-, -C(=O)-O-Z31-, or -C(=O)-NH-Z31-, where Z31 is an aliphatic alkyl group with 1 to 6 carbon atoms, phenyl, fluorinated phenyl, trifluoromethyl-substituted phenyl, or a group with 7 to 20 carbon atoms obtained by combining them, and may also contain a carbonyl group, ester bond, ether bond, or hydroxyl group; Z4 can be a single bond or an alkyl group with 1 to 30 carbon atoms that may contain heteroatoms; f1 and f2 are independently 0 or 1, but when Z4 is a single bond, f1 and f2 are 0; R31 to R48 are each an independent hydrocarbon group with 1 to 20 carbon atoms, which may also contain heteroatoms; furthermore, R31 and R32 may also bond to each other and form a ring with the sulfur atoms they are bonded to, and R33 and R34, R36 and R37, or R39 and R40 may also bond to each other and form a ring with the sulfur atoms they are bonded to; RHF is a hydrogen atom or a trifluoromethyl group; Xa- is a non-nucleophilic relative ion.

5. The chemical amplification positive inhibitor composition of claim 1 further contains (E) organic solvent.

6. The chemical amplification positive resist composition as requested in item 1, which provides a resist film with an extinction coefficient (k value) of less than 0.01 for inspection light with a wavelength of 300~400nm.

7. A method for forming a resist pattern, comprising the following steps: forming a resist film on a substrate using a chemically amplified positive resist composition as claimed in any one of claims 1 to 6, irradiating the resist film with a pattern using high-energy rays, and developing the irradiated resist film with an alkaline developer.

8. The method for forming the resist pattern as described in claim 7, wherein, The high-energy rays are extreme ultraviolet rays or electron beams.

9. The method for forming the resist pattern as described in claim 7, wherein, The outermost surface of the substrate is made of a material selected from at least one of chromium, silicon, tantalum, molybdenum, cobalt, nickel, tungsten and tin.

10. The method for forming the resist pattern as described in claim 7, wherein, The substrate is a blank photomask.

11. A blank photomask comprising: a resist film of a chemically amplified positive resist composition obtained from any one of claims 1 to 6.

12. The blank photomask, as requested in item 11, also has an antistatic film.

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