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KR-20260064581-A - RESIST COMPOSITION AND PATTERNING PROCESS

KR20260064581AKR 20260064581 AKR20260064581 AKR 20260064581AKR-20260064581-A

Abstract

[Problem] To provide a resist composition comprising a photosensitive onium salt having a highly photosensitive cation, which has good sensitivity, small edge roughness or dimensional deviation, excellent resolution, and good storage stability, and a method for forming a pattern. [Solution] A resist composition comprising a resin (A) whose alkali solubility is increased by the action of an acid, and a carboxylic acid (D) represented by the following general formula (1), and also comprising a photogenerator (B) and/or a photodisintegrating base (C). (In the formula, R1 is an organic group having 1 to 30 carbon atoms, and R2 is an organic group that may contain fluorine atoms having 1 to 8 carbon atoms.)

Inventors

  • 히다 겐타로
  • 오토모 유타로

Assignees

  • 신에쓰 가가꾸 고교 가부시끼가이샤

Dates

Publication Date
20260507
Application Date
20251027
Priority Date
20241031

Claims (18)

  1. A resist composition comprising a resin (A) whose alkali solubility is increased by the action of an acid, and a carboxylic acid (D) represented by the following general formula (1), and also comprising either or both of a photogenerator (B) and a photodisintegrating base (C). (In the formula, R1 is an organic group having 1 to 30 carbon atoms, and R2 is an organic group that may contain fluorine atoms having 1 to 8 carbon atoms.)
  2. A resist composition according to claim 1, characterized in that the carboxylic acid (D) is one or more selected from the carboxylic acids represented by the following general formulas (2) and (2)'. (In the formula, R₂ is an organic group that may contain a fluorine atom having 1 to 8 carbon atoms. R₄ to R₅ are each independently an organic group having 1 to 27 carbon atoms that may contain a heteroatom, a hydrogen atom, or a fluorine atom. Provided that the sum of the carbon atoms of R₄ and R₅ is at most 28. Additionally, R₄ and R₅ may be bonded to each other to form a ring. Ar is an aromatic group having 6 to 30 carbon atoms that may have a substituent.)
  3. A resist composition according to claim 1, characterized in that the acid dissociation constant pKa(C) of the photodissociable base (C) is pKa(C) > pKa(D) with respect to the acid dissociation constant pKa(D) of the carboxylic acid (D).
  4. A resist composition characterized in that, in any one of claims 1 to 3, the photogenerator (B) is represented by the following general formula (3), the photodisintegrating base (C) is represented by the following general formula (4), or both. (In the formula, R6 is an organic group having 1 to 40 carbon atoms. R7 to R9 are electron-spherical groups. l1, m1, and n1 are integers from 1 to 3, respectively. If l1, m1, and n1 are integers greater than or equal to 2, R7 to R9 may be the same or different.) (In the formula, R10 is an organic group having 1 to 40 carbon atoms. R11 to R13 are electron-spherical groups. l2, m2, and n2 are integers from 1 to 3, respectively. If l2, m2, and n2 are integers greater than or equal to 2, R11 to R13 may be the same or different.)
  5. A resist composition according to claim 4, wherein R7 to R9 in the general formula (3) and R11 to R13 in the general formula (4) are each independently one or more selected from organic groups including a fluorine atom, an iodine atom, a perfluoroalkyl group, a nitro group, a cyano group, and a carbonyl group, an amide bond, or an unsaturated bond.
  6. A resist composition according to any one of claims 1 to 3, wherein either or both of the photogenerator (B) and the photodisintegrating base (C) are included as repeating units of the resin (A), and wherein the photogenerator (B) is represented by the following general formula (5), the photodisintegrating base (C) is represented by the following general formula (6), or both. (In the formula, R₁₄ is each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z₁ is a single bond or a divalent organic group having 1 to 40 carbon atoms, and may include one or more selected from ester bonds, ether bonds, lactone rings, aromatic rings, fluorine atoms, bromine atoms, and iodine atoms. M⁺ is a sulfonium cation.) (In the formula, RA is each independently a hydrogen atom or a methyl group. Z3 is a single bond or a divalent organic group having 1 to 40 carbon atoms, and may include one or more selected from ester bonds, ether bonds, lactone rings, aromatic rings, fluorine atoms, bromine atoms, and iodine atoms. M + is a sulfonium cation.)
  7. A resist composition according to claim 6, characterized in that the M + in the above general formulas (5) and (6) is represented by the following general formula (7). (In the formula, R₁₆ – R₁₅ are electron spheres. o, p, and q are integers from 1 to 3, respectively. If o, p, and q are integers greater than or equal to 2, R₁₆ – R₅₅ may be the same or different.)
  8. A resist composition according to claim 7, wherein the R 16 to R 18 in the general formula (7) are each independently one or more selected from a fluorine atom, an iodine atom, a perfluoroalkyl group, a nitro group, a cyano group, and an organic group including a carbonyl group, an amide bond, or an unsaturated bond.
  9. As a pattern forming method, (i) a process of forming a resist film by applying a resist composition described in any one of claims 1 to 3 onto a substrate, and (ii) a process of exposing the above resist film to high-energy rays, and (iii) A process of developing the above-mentioned exposed resist film using a developer solution A pattern forming method characterized by including
  10. A resist composition comprising a resin (A) whose alkali solubility is increased by the action of an acid, and a carboxylic acid (D) represented by the following general formula (1'), and also comprising either or both of a photogenerator (B) and a photodisintegrating base (C). (In the formula, R is an organic group having 1 to 30 carbon atoms that may have substituents, and R' is an organic group that may contain a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, or a fluorine atom having 1 to 9 carbon atoms. k is an integer from 1 to 3, and when k is 2 or greater, R' may be identical or different.)
  11. A resist composition according to claim 10, characterized in that the carboxylic acid (D) is one or more selected from the carboxylic acids represented by the following general formulas (1a) and (1b). (In the formula, R1a is a hydrocarbyl group having 1 to 30 carbon atoms substituted or unsubstituted with a hydroxyl group, an alkoxy group, a halogen atom, a nitro group, an amide group, or a heteroatom, and may include a halogen atom, a carbonyl group, an amide group, or a hydroxyl group. However, it does not include an ester group. L1a is a single bond or a divalent linker and may include an ester bond, an ether bond, a lactone ring, an aromatic ring, a fluorine atom, a bromine atom, or an iodine atom. n1a is an integer from 0 to 3, and when n1a is 2 or more, R1a may be the same or different. Provided that the total number of carbon atoms in the formula is at most 58.) (In the formula, R 2b is a hydrocarbyl group having 1 to 30 carbon atoms substituted or unsubstituted with a hydroxyl group, an alkoxy group, a nitro group, or a heteroatom, and may include a halogen atom, a carbonyl group, an amide group, or a hydroxyl group, or may include an alicyclic group or an aromatic cyclic group. L 2b is a single bond or a divalent linker and may include an ester bond, an ether bond, a lactone ring, an aromatic ring, a fluorine atom, a bromine atom, or an iodine atom. Rf 1b and Rf 2b are each independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group.)
  12. A resist composition according to claim 10, characterized in that the acid dissociation constant pKa(C) of the photodissociable base (C) is pKa(C) > pKa(D) with respect to the acid dissociation constant pKa(D) of the carboxylic acid (D).
  13. A resist composition characterized in that, in any one of claims 10 to 12, the photogenerator (B) is represented by the following general formula (3), the photodisintegrating base (C) is represented by the following general formula (4), or both. (In the formula, R6 is an organic group having 1 to 40 carbon atoms. R7 to R9 are electron-spherical groups. l1, m1, and n1 are integers from 1 to 3, respectively. If l1, m1, and n1 are integers greater than or equal to 2, R7 to R9 may be the same or different.) (In the formula, R10 is an organic group having 1 to 40 carbon atoms. R11 to R13 are electron-spherical groups. l2, m2, and n2 are integers from 1 to 3, respectively. If l2, m2, and n2 are integers greater than or equal to 2, R11 to R13 may be the same or different.)
  14. A resist composition according to claim 13, wherein the R7 to R9 in the general formula (3) and the R11 to R13 in the general formula (4) are each independently one or more selected from organic groups including a fluorine atom, an iodine atom, a perfluoroalkyl group, a nitro group, a cyano group, and a carbonyl group, an amide bond, or an unsaturated bond.
  15. A resist composition according to any one of claims 10 to 12, wherein either or both of the photogenerator (B) and the photodisintegrating base (C) are included as repeating units of the resin (A), and wherein the photogenerator (B) is represented by the following general formula (5), the photodisintegrating base (C) is represented by the following general formula (6), or both. (In the formula, R₁₄ is each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Z₁ is a single bond or a divalent organic group having 1 to 40 carbon atoms, and may include one or more selected from ester bonds, ether bonds, lactone rings, aromatic rings, fluorine atoms, bromine atoms, and iodine atoms. M⁺ is a sulfonium cation.) (In the formula, RA is each independently a hydrogen atom or a methyl group. Z3 is a single bond or a divalent organic group having 1 to 40 carbon atoms, and may include one or more selected from ester bonds, ether bonds, lactone rings, aromatic rings, fluorine atoms, bromine atoms, and iodine atoms. M + is a sulfonium cation.)
  16. A resist composition according to claim 15, characterized in that the M + in the above general formulas (5) and (6) is represented by the following general formula (7). (In the formula, R₁₆ – R₁₅ are electron spheres. o, p, and q are integers from 1 to 3, respectively. If o, p, and q are integers greater than or equal to 2, R₁₆ – R₅₅ may be the same or different.)
  17. A resist composition according to claim 16, wherein the R 16 to R 18 in the above general formula (7) are each independently selected from one or more organic groups including a fluorine atom, an iodine atom, a perfluoroalkyl group, a nitro group, a cyano group, and a carbonyl group, an amide bond, or an unsaturated bond.
  18. As a pattern forming method, (i) a process of forming a resist film by applying a resist composition described in any one of claims 10 to 12 onto a substrate, and (ii) a process of exposing the above resist film to high-energy rays, and (iii) A process of developing the above-mentioned exposed resist film using a developer solution A pattern forming method characterized by including

Description

Resist Composition and Patterning Process The present invention relates to a resist composition and a pattern forming method. With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. This is because the widespread adoption of 5G high-speed communication and artificial intelligence (AI) is creating a need for high-performance devices to process them. As a cutting-edge miniaturization technology, mass production of 5 nm node devices is being carried out using extreme ultraviolet (EUV) lithography with a wavelength of 13.5 nm. Furthermore, the use of EUV lithography is being explored for next-generation 3 nm node and next-next-generation 2 nm node devices as well. In lithography using a DUV light source, namely a KrF excimer laser or an ArF excimer laser, a chemically amplified resist composition that changes solubility in a developer by causing a reaction of a base polymer using an acid generated from a photosensitive compound (photoacid generator) by exposure as a catalyst has realized high sensitivity and high resolution lithography and has driven miniaturization as a main resist composition used in actual production processes. In next-generation lithography such as EUV, chemically amplified resist compositions are continuously being widely studied and are reaching commercialization. Meanwhile, with miniaturization, the demand for improved resist performance is increasing even further. In particular, since variations in resist pattern dimensions (e.g., Line With Roughness (LWR)) affect pattern dimensional variations after substrate processing and can ultimately impact the operational stability of the device, it is required to suppress this to the extreme. Furthermore, it is also required that the resist composition possess good storage stability. EUV light sources currently in use have low output power but possess high energy due to their short wavelength, so the number of photons included during exposure is very small. Consequently, the amount of photoresist that is sensitized during EUV exposure is reduced compared to DUV exposure, and as a result, the distribution of acid within the resist film becomes non-uniform. It is known that such photon shot noise causes a degradation in LWR performance (Non-patent Literature 1). In order to improve performance degradation caused by such a low number of photons, it is effective to add a photogenerator with high photosensitivity. For example, Patent Documents 1 and 2 propose an onium salt of a sulfonium cation substituted with a fluorine atom. However, compounds having cations with good quantum efficiency and high photoreactivity have problems in terms of storage stability due to their high reactivity. It is known that storage stability deteriorates when combined with anions with high nucleational activity, and Patent Document 3 reports that stability is improved by adding carboxylic acids such as acetic acid or lactic acid or fluoroalcohols. Figure 1 is a diagram showing an example of the trend of sensitivity variation when the storage period is extended in the storage stability evaluation. As mentioned above, there was a need to develop a resist composition containing a photosensitive onium salt having a highly photosensitive cation, which has good sensitivity, small edge roughness or dimensional deviation, excellent resolution, and good storage stability, as well as a pattern forming method. As mentioned above, photosensitive iodium salts having highly photosensitive cations are unstable and gradually decompose during storage as a resist solution, causing results such as fluctuations in resist sensitivity or deterioration of lithography performance. One of the hypothesized mechanisms for the decomposition of iodium salts during storage is the reaction between nucleating components contained in the resist solution and highly photosensitive cations. The nucleating components mentioned here include components such as hydroxide ions, carboxylate ions, and amines, as well as polymers, polymers, quenchers, and solvents essential to the resist composition. Highly photosensitive cations have high absorption efficiency of EUV light and also high electron accepting capacity, which allows for the high sensitivity of the resist. On the other hand, due to the instability of the aforementioned highly photosensitive cations, the systems that can be handled stably have been limited. The inventors examined various additives to suppress the decomposition of the highly photosensitive cation in a resist composition comprising a photosensitive onium salt having a highly photosensitive cation. As a result, they discovered that by adding a specific acid compound, good sensitivity, small edge roughness and dimensional deviation, excellent resolution, and the problem of storage stability could be overcome. The specific acid compound in the present invention is Brønsted acid, which dissociates in a solution containing the resist comp