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JP-7856029-B2 - Resist material and pattern formation method

JP7856029B2JP 7856029 B2JP7856029 B2JP 7856029B2JP-7856029-B2

Inventors

  • 畠山 潤

Assignees

  • 信越化学工業株式会社

Dates

Publication Date
20260511
Application Date
20230310
Priority Date
20220325

Claims (14)

  1. A resist material comprising a quencher containing a sulfonium salt represented by the following formula (1) or Q-13 . (In the formula, m is an integer from 0 to 5, n is an integer from 0 to 3, p is 0 or 1, q is an integer from 0 to 4, r is 1 or 2, and s is an integer from 1 to 3.) R1 is a single bond, an ether bond, a thioether bond, or an ester bond. R2 is a single bond or an alkanediyl group having 1 to 20 carbon atoms, and the alkanediyl group may have a fluorine atom or a hydroxyl group. R3 and R4 are each independently a saturated hydrocarbyl group having 1 to 12 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or an aryl group having 6 to 10 carbon atoms, and the saturated hydrocarbyl group, alkenyl group, alkynyl group, and aryl group may contain an oxygen atom or a sulfur atom. Furthermore, R3 and R4 may bond to each other to form a ring with the carbon atoms to which they are bonded. R5 is a fluorine atom, a C1-C4 alkyl group which may be substituted with a fluorine atom, a C1-C4 alkoxy group which may be substituted with a fluorine atom, or a C1-C4 alkylthio group which may be substituted with a fluorine atom. R 6 is a hydroxyl group, an alkoxycarbonyl group having 2 to 4 carbon atoms, a nitro group, a cyano group, a chlorine atom, a bromine atom, or an amino group. R7 is a saturated hydrocarbyl group having 1 to 20 carbon atoms, a saturated hydrocarbyloxy group having 1 to 20 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 20 carbon atoms, a saturated hydrocarbyloxycarbonyl group having 2 to 20 carbon atoms, or a saturated hydrocarbylsulfonyloxy group having 1 to 4 carbon atoms, which may contain at least one selected from a hydroxyl group, a carboxyl group, a nitro group, a cyano group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an amino group, or a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a hydroxyl group, an amino group, and an ether bond. R8 is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. When s=1, the two R8 groups may be identical or different, and they may bond to each other to form a ring with the sulfur atom to which they are bonded. Circle Ar is an aromatic group with 6 to 18 carbon atoms and a (m+n+1) valency, and may contain an oxygen atom, a sulfur atom, or a nitrogen atom. X- is a non-nucleophilic counterion that is a weaker acid than sulfonic acid.
  2. The resist material according to claim 1, wherein the non-nucleophilic counterion represented by X- is a carboxylic acid anion, a sulfonamide anion, a fluorine-free methidoate anion, a phenoxide anion, a halide anion, or a carbonate anion.
  3. The resist material according to claim 2, wherein the carboxylic acid anion is represented by the following formula (2)-1, the sulfonamide anion is represented by the following formula (2)-2, the fluorine atom-free methidoic acid anion is represented by the following formula (2)-3, and the phenoxide anion is represented by the following formula (2)-4. (In the formula, R 11 is a C1-C24 hydrocarbyl group which may contain a hydrogen atom, a fluorine atom, or a heteroatom.) R 12 is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain heteroatoms. R 13 is a hydrocarbyl group having 1 to 20 carbon atoms, which may contain a hydrogen atom or a heteroatom. R14 to R16 are each independently a hydrocarbyl group having 1 to 10 carbon atoms, which may contain heteroatoms. R 17 is a halogen atom, a hydroxyl group, a cyano group, a nitro group, an amino group, a C2-C10 alkylcarbonylamino group, a C1-C10 alkylsulfonylamino group, a C1-C10 alkylsulfonyloxy group, a C1-C10 alkyl group, a phenyl group, a C1-C10 alkoxy group, a C1-C10 alkylthio group, a C2-C10 alkoxycarbonyl group, a C1-C10 acyl group, or a C1-C10 acyloxy group, and some or all of the hydrogen atoms bonded to these carbon atoms may be substituted with fluorine atoms. k is an integer between 0 and 5.
  4. The resist material according to claim 1, wherein m is an integer from 1 to 5.
  5. Furthermore, the resist material according to claim 1 includes an acid generator that produces a strong acid.
  6. The resist material according to claim 5, wherein the strong acid is a sulfonic acid, a fluorinated imido acid, or a fluorinated methidoic acid.
  7. Furthermore, the resist material according to claim 1, comprising an organic solvent.
  8. Furthermore, the resist material according to claim 1, comprising a base polymer.
  9. The resist material according to claim 8, wherein the base polymer includes a repeating unit represented by the following formula (a1) or a repeating unit represented by the following formula (a2). (In the formula, R A is independently a hydrogen atom or a methyl group.) X1 is a linking group having 1 to 12 carbon atoms, containing at least one of a single bond, a phenylene group or a naphthylene group, or an ester bond, an ether bond, and a lactone ring. X2 is either a single bond or an ester bond. X3 is a single bond, an ether bond, or an ester bond. R21 and R22 are independently acid-unstable groups. R 23 is a fluorine atom, a trifluoromethyl group, a cyano group, a saturated hydrocarbyl group having 1 to 6 carbon atoms, a saturated hydrocarbyloxy group having 1 to 6 carbon atoms, a saturated hydrocarbylcarbonyl group having 2 to 7 carbon atoms, a saturated hydrocarbylcarbonyloxy group having 2 to 7 carbon atoms, or a saturated hydrocarbyloxycarbonyl group having 2 to 7 carbon atoms. R 24 is a single bond or an alkanediyl group having 1 to 6 carbon atoms, and a portion of the -CH2- of the alkanediyl group may be substituted with an ether bond or an ester bond. a is either 1 or 2. b is an integer between 0 and 4, where 1 ≤ a + b ≤ 5.
  10. The resist material according to claim 9, which is a chemically amplified positive-type resist material.
  11. The resist material according to claim 8, wherein the base polymer comprises at least one selected from repeating units represented by the following formulas (f1) to (f3). (In the formula, R A is independently a hydrogen atom or a methyl group.) Z1 is a single bond, an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, or -O- Z11- , -C(=O)-O- Z11- , or -C(=O)-NH- Z11- . Z11 is an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a naphthylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, or a hydroxyl group. Z2 is either a single bond or an ester bond. Z3 is a single bond, -Z31 -C(=O)-O-, -Z31 -O-, or -Z31 -O-C(=O)-. Z31 is an aliphatic hydrocarbylene group having 1 to 12 carbon atoms, a phenylene group, or a group having 7 to 18 carbon atoms obtained by combining these, and may contain a carbonyl group, an ester bond, an ether bond, an iodine atom, or a bromine atom. Z4 is a methylene group, a 2,2,2-trifluoro-1,1-ethanediyl group, or a carbonyl group. Z 5 is a single bond, a methylene group, an ethylene group, a phenylene group, a fluorinated phenylene group, a phenylene group substituted with a trifluoromethyl group, -O-Z 51- , -C(=O)-O-Z 51- , or -C(=O)-NH-Z 51- . Z 51 is a phenylene group substituted with an aliphatic hydrocarbylene group having 1 to 6 carbon atoms, a phenylene group, a fluorinated phenylene group, or a trifluoromethyl group, and may contain a carbonyl group, an ester bond, an ether bond, a hydroxyl group, or a halogen atom. R31 to R38 are each independently a C1 to C20 hydrocarbyl group which may contain a halogen atom or a heteroatom. Furthermore, R33 and R34 or R36 and R37 may bond to each other to form a ring with the sulfur atom to which they are bonded. M- is a non-nucleophilic counterion.
  12. Furthermore, the resist material according to claim 1, further comprising a surfactant.
  13. A pattern forming method comprising the steps of: forming a resist film on a substrate using a resist material according to any one of claims 1 to 12; exposing the resist film with high-energy rays; and developing the exposed resist film using a developer.
  14. The pattern formation method according to claim 13, wherein the high-energy beam is a KrF excimer laser beam, an ArF excimer laser beam, an electron beam, or extreme ultraviolet light with a wavelength of 3 to 15 nm.

Description

This invention relates to a resist material and a pattern forming method. With the increasing integration and speed of LSIs, the miniaturization of pattern rules is progressing rapidly. This is due to the advancement of 5G high-speed communication and the proliferation of artificial intelligence (AI), which necessitates high-performance devices for processing this data. At the forefront of miniaturization technology, mass production of 5nm node devices is underway using extreme ultraviolet (EUV) lithography at a wavelength of 13.5nm. Furthermore, research using EUV lithography is progressing for next-generation 3nm node and the following-generation 2nm node devices, and IMEC in Belgium has announced the development of 1nm and 0.7nm devices. As miniaturization progresses, image blurring due to acid diffusion is becoming a problem. To ensure resolution in fine patterns of 45 nm and beyond, it has been suggested that controlling acid diffusion is crucial, in addition to improving dissolution contrast as previously proposed (Non-Patent Literature 1). However, since chemically amplified resist materials increase sensitivity and contrast through acid diffusion, attempting to suppress acid diffusion to the extreme by lowering the post-exposure bake (PEB) temperature or shortening the time results in a significant decrease in sensitivity and contrast. The triangle trade-off relationship between sensitivity, resolution, and edge roughness (LWR) is shown. Improving resolution requires suppressing acid diffusion, but a shorter acid diffusion distance leads to decreased sensitivity. Adding an acid generator that produces bulky acids to suppress acid diffusion is effective. Therefore, it has been proposed to incorporate repeating units derived from onium salts having polymerizable unsaturated bonds into the polymer. In this case, the polymer also functions as an acid generator (polymer-bound type acid generator). Patent Document 1 proposes sulfonium salts and iodonium salts having polymerizable unsaturated bonds that generate specific sulfonic acids. Patent Document 2 proposes sulfonium salts in which sulfonic acids are directly linked to the main chain. To form finer patterns, it is necessary not only to suppress acid diffusion but also to improve dissolution contrast. To improve dissolution contrast, polarity-converting base polymers that generate phenolic or carboxyl groups through acid-induced deprotection reactions are used. Using resist materials containing these polymers, positive patterns are formed by alkaline development, and negative patterns are formed by organic solvent development. Positive patterns have higher resolution. This is because alkaline development results in higher dissolution contrast. Furthermore, base polymers that generate carboxyl groups have higher alkaline solubility than base polymers that generate phenolic groups, allowing for higher dissolution contrast. Therefore, carboxyl-generating base polymers are increasingly being used. Non-chemically amplified resist materials with a main chain decomposition type, where the main chain decomposes upon exposure, reducing molecular weight and improving solubility in organic solvent developers, are not affected by acid diffusion but have low dissolution contrast. Chemically amplified resist materials with the aforementioned polarity conversion function offer higher resolution. To further improve dissolution contrast, it has been proposed to add an acid generator with polarity conversion capabilities to the resist material, in addition to a base polymer with polarity conversion capabilities. Patent documents 3 and 4 show resist materials containing sulfonium salts having a tertiary ester-type acid-unstable group in the cationic portion, while patent documents 5 and 6 show resist materials containing sulfonium salts having an acid-unstable group in the anionic portion. However, the alicyclic and dimethylphenylcarbinol-type acid-unstable groups described in these documents were insufficient in improving dissolution contrast and reducing swelling. Japanese Patent Publication No. 2006-045311Japanese Patent Publication No. 2006-178317Japanese Patent Publication No. 2011-006400Japanese Patent Publication No. 2021-070692Japanese Patent Publication No. 2014-224236International Publication No. 2021/200056 SPIE Vol. 6520 65203L-1 (2007) [Resist material] The resist material of the present invention comprises a quencher containing a sulfonium salt of a weak acid having a tertiary ester-type acid-unstable group having an aromatic group as a cation. [A sulfonium salt of a weak acid having a tertiary ester-type acid-unstable group with an aromatic group as its cation] The sulfonium salt of a weak acid having the aforementioned aromatic group-containing tertiary ester-type acid-unstable group as a cation is represented by the following formula (1). In equation (1), m is an integer between 0 and 5, n is an integer between 0 and 3, p is 0 or 1, q is an integer betw