Resist composition and pattern forming method

Abstract

Provided is a resist composition which generates an acid by exposure to light and which changes the solubility in a developing solution due to the action of the acid, the resist composition being characterized by containing a resin (A), an acid diffusion inhibitor (B), an additive (C), and a solvent (D), a structural unit with a photo-acid generator is introduced into the matrix resin, in addition, a strong electron withdrawing group such as trifluoromethyl or nitro is introduced into the structural unit containing the photo-acid generator in the matrix resin, so that the acid production efficiency of the structural unit of the photo-acid generator in the matrix resin can be improved, and the resolution of the pattern can be further improved; the roughness is reduced, and cracks are reduced. The resin (A) comprises a structural unit represented by a general formula (1).

Description

Technical Field

[0001] The present invention relates to the technical field of resist compositions and pattern forming methods. Background Art

[0002] In recent years, advances in photolithography have led to a rapid decrease in pattern size in the manufacture of semiconductor devices and liquid crystal displays. As a method for miniaturization, this reduction is generally achieved by shortening the wavelength (increasing the energy) of the exposure light source. Specifically, ultraviolet light, represented by g-rays and i-rays, as well as KrF excimer lasers and ArF excimer lasers, can be used for mass production of semiconductor devices. Furthermore, research is also underway into EUV (extreme ultraviolet light), EB (electron beams), and X-rays, all of which have even shorter wavelengths than these excimer lasers.

[0003] Resist materials are required to have sensitivity to these exposure light sources and photolithographic properties such as resolution that enables reproduction of fine-scale patterns.

[0004] Generally speaking, resists typically consist of a resin component whose solubility in alkaline developer is increased by the action of acid, and a photoacid generator component. After exposure, the acid generator generates acid, increasing the polarity of the resin due to the acid, making the exposed portion of the resist film more soluble in the alkaline developer. Existing formulations are mixtures of the resin and photoacid generator. During the exposure process, the acid generator and resin exhibit inherent incompatibility, leading to phase separation, aggregation, and uneven distribution of the photoacid generator within the resin. This, in turn, causes migration of the photoacid generator after exposure baking, preventing the pattern from achieving high resolution, high sensitivity, and low line-edge roughness.

[0005] Therefore, it is urgent to develop a new type of resist composition to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0006] The present invention addresses the problems existing in the prior art and prepares a resist composition that generates acid upon exposure and changes its solubility in a developer due to the action of the acid. The resist composition comprises a resin (A), an acid diffusion inhibitor (B), an additive (C), and a solvent (D).

[0007] The resin (A) comprises a structural unit represented by the general formula (1):

[0008]

[0009] In the general formula (1), R1 represents a monovalent organic group, including but not limited to an alkyl group having 1 to 4 carbon atoms, an alkoxy group, an alkenyl group, a phenyl group, a halogen atom, a halogen-substituted or polysubstituted alkyl group having 1 to 4 carbon atoms, an alkoxy group, an alkenyl group, and a nitro group; wherein m is a positive integer ranging from 1 to 3; R2 represents a monovalent organic group, including but not limited to an alkyl group having 1 to 4 carbon atoms, a phenyl group, a phenyl group, and a halogen-substituted or polysubstituted alkyl group having 1 to 4 carbon atoms; wherein n is a positive integer ranging from 1 to 3;

[0010] Furthermore, in the general formula (1), R1 comprises one or more combinations of methyl, trifluoromethyl, and nitro, wherein m is 1 or 2; R2 in the general formula (1) comprises one or more combinations of phenyl, p-methylphenyl, p-ethylphenyl, p-propylphenyl, p-butylphenyl, and p-tert-butylphenyl, wherein n is 2 or 3;

[0011] Furthermore, the general formula (1) comprises one or more combinations of the structural units shown in the chemical formula (2), wherein Ph represents a phenyl group:

[0012]

[0013] Furthermore, the molar percentage of the structural unit represented by the general formula (1) in the resin (A) is between 5 mol% and 10 mol%;

[0014] Preferably, the molar percentage of the structural unit represented by the general formula (1) in the resin (A) is between 6.2 mol% and 7 mol%;

[0015] Furthermore, the resin (A) comprises one or more combinations of methacrylate structural units comprising a cycloalkane structure as shown in chemical formula (3):

[0016]

[0017] Furthermore, the resin (A) comprises one or more combinations of aromatic vinyl structural units containing or not containing hydroxyl groups as shown in chemical formula (4):

[0018]

[0019] Furthermore, the resin (A) comprises one or more combinations of aromatic methacrylate structural units containing or not containing hydroxyl groups as shown in chemical formula (5):

[0020]

[0021] Further, the resist composition comprises an acid diffusion inhibitor (B), and the acid diffusion inhibitor (B) comprises one or more combinations of the following compounds: n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, dialkylamine, di-n-heptylamine, di-n-octylamine, dicyclohexylamine, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, n-dodecylamine, diethanolamine, triethanolamine, diisopropanolamine, trialkylamine, isopropanolamine, di-n-octanolamine, and tri-n-octanolamine;

[0022] Preferably, the acid diffusion inhibitor (B) comprises one of tri-n-pentylamine or tri-n-octylamine;

[0023] Furthermore, the resist composition comprises an additive (C), wherein the additive (C) is one or more combinations of organic carboxylic acids or oxygen-containing phosphoric acids and their derivatives;

[0024] Preferably, the additive comprises one or more combinations of acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, phosphoric acid, phosphonic acid, and phosphinic acid;

[0025] The second aspect of the present invention provides a pattern forming method, which includes the steps of coating the above-mentioned resist composition on a substrate; after performing a heat treatment before exposure, exposing the substrate through a photomask using any one of high-energy rays, electron beams or extreme ultraviolet light with a wavelength of 140 to 250 nm; and after the exposure and heat treatment, developing the substrate using a developer; using an alkaline aqueous solution or an organic solvent as the developer to dissolve the exposed or unexposed part, thereby obtaining a positive or negative pattern.

[0026] Beneficial effects

[0027] By introducing a structural unit containing a photoacid generator into the main resin, the problems of phase separation, aggregation, and uneven initial distribution of the photoacid generator, which are caused by mixing the photoacid generator substance with the main resin, can be avoided. In addition, the introduction of strong electron-withdrawing groups, such as trifluoromethyl or nitro groups, into the structural unit containing the photoacid generator in the main resin can improve the acid generation efficiency of the photoacid generator structural unit in the main resin, further improving the resolution of the pattern, reducing roughness, and reducing the occurrence of cracks. DETAILED DESCRIPTION

[0028] The present invention is described in detail below.

[0029] A resist composition that generates acid upon exposure and changes its solubility in a developer due to the action of the acid, comprising a resin A, an acid diffusion inhibitor B, an additive C, and a solvent D;

[0030] The resin A contains the structural unit shown in the general formula (1):

[0031]

[0032] In the general formula (1), R1 represents a monovalent organic group, including but not limited to an alkyl group having 1 to 4 carbon atoms, an alkoxy group, an alkenyl group, a phenyl group, a halogen atom, a halogen-substituted or polysubstituted alkyl group having 1 to 4 carbon atoms, an alkoxy group, an alkenyl group, and a nitro group; wherein m is a positive integer ranging from 1 to 3; R2 represents a monovalent organic group, including but not limited to an alkyl group having 1 to 4 carbon atoms, a phenyl group, a phenyl group, and a halogen-substituted or polysubstituted alkyl group having 1 to 4 carbon atoms; wherein n is a positive integer ranging from 1 to 3;

[0033] In the general formula (1), R1 comprises one or more combinations of methyl, trifluoromethyl, and nitro, wherein m is 1 or 2; R2 in the general formula (1) comprises one or more combinations of phenyl, p-methylphenyl, p-ethylphenyl, p-propylphenyl, p-butylphenyl, and p-tert-butylphenyl, wherein n is 2 or 3;

[0034] The general formula (1) comprises one or more combinations of the structural units shown in the chemical formula (2), wherein Ph represents a phenyl group:

[0035]

[0036] Preferably, the general formula (1) comprises one or more combinations of the following compounds, wherein Ph represents a phenyl group:

[0037]

[0038] Particularly preferably, the general formula (1) comprises one or more combinations of the following compounds, wherein Ph represents a phenyl group:

[0039]

[0040] The molar percentage of the structural unit represented by general formula (1) in resin A is between 5 mol% and 10 mol%;

[0041] Preferably, the molar percentage of the structural unit represented by general formula (1) in resin A is between 6.2 mol% and 7 mol%;

[0042] Resin A contains a methacrylate structural unit containing a cycloalkane structure as shown in chemical formula (3):

[0043]

[0044] Preferably, resin A comprises one or more combinations of the following methacrylate structural units of cycloalkane structures:

[0045]

[0046] Particularly preferably, resin A comprises one or more combinations of the following methacrylate structural units of cycloalkane structures:

[0047]

[0048] Resin A comprises an aromatic vinyl structural unit containing or not containing a hydroxyl group as shown in chemical formula (4):

[0049]

[0050] Preferably, resin A comprises one or more combinations of the following aromatic vinyl structural units containing or not containing hydroxyl groups:

[0051]

[0052] Particularly preferably, resin A comprises one or more combinations of the following aromatic vinyl structural units containing or not containing hydroxyl groups:

[0053]

[0054] Resin A comprises one or more combinations of aromatic methacrylate structural units containing or not containing hydroxyl groups as shown in chemical formula (5):

[0055]

[0056] Preferably, resin A comprises one or more combinations of aromatic methacrylate structural units containing or not containing hydroxyl groups as shown below:

[0057]

[0058] The resist composition comprises an acid diffusion inhibitor B, wherein the acid diffusion inhibitor B comprises one or more combinations of the following compounds: n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, dialkylamines, di-n-heptylamine, di-n-octylamine, dicyclohexylamine, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, n-dodecylamine, diethanolamine, triethanolamine, diisopropanolamine, trialkylamines, isopropanolamine, di-n-octanolamine, and tri-n-octanolamine;

[0059] Preferably, the acid diffusion inhibitor B comprises one of tri-n-pentylamine or tri-n-octylamine;

[0060] Particularly preferably, the acid diffusion inhibitor B comprises tri-n-pentylamine.

[0061] The resist composition comprises an additive C, wherein the additive C is one or more combinations of organic carboxylic acids or oxygen-containing phosphoric acids and their derivatives;

[0062] Preferably, the additive C comprises one or more combinations of acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, phosphoric acid, phosphonic acid, and phosphinic acid;

[0063] Particularly preferably, additive C is malic acid.

[0064] The resist composition can be prepared by dissolving the resist material in a solvent D. As examples of the solvent, in the embodiment of the present invention, the solvent includes lactones such as γ-butyrolactone; ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl n-amyl ketone, methyl isoamyl ketone, 2-heptanone; diols; compounds having ester bonds such as ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate or dipropylene glycol monoacetate; monomethyl ethers and monoethyl ethers of the above polyols or compounds having ester bonds; derivatives of polyols, such as compounds having ether bonds, such as monoalkyl ethers, monopropyl ethers and monobutyl ethers; Ether ethers or monophenyl ethers, such as propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME); cyclic ether acetates such as dioxane, methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, and butyl ether; ethoxy esters such as methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, and ethyl propionate; one or more combinations of anisole, ethyl benzyl ether, tolyl methyl ether, diphenyl ether, dibenzyl ether, phenethyl ether, butylphenyl ether, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene.

[0065] Preferably, the solvent in the embodiment of the present invention is preferably propylene glycol monomethyl ether acetate PGMEA and propylene glycol monomethyl ether PGME.

[0066] The present invention also provides a pattern forming method, which includes the steps of coating the above-mentioned resist composition on a substrate; after performing a heat treatment before exposure, exposing the substrate through a photomask using any one of high-energy rays, electron beams or extreme ultraviolet light with a wavelength of 140 to 250 nm; and after the exposure and heat treatment, developing the substrate using a developer; using an alkaline aqueous solution or an organic solvent as the developer to dissolve the exposed or unexposed part, thereby obtaining a positive or negative pattern.

[0067] As for the developer involved in the embodiment of the present invention, TMAH can be cited as the developer of alkaline aqueous solution; as the developer of organic solvent development, 2-octanone, 2-nonanone, 2-heptanone, 3-heptanone, 4-heptanone, 2-hexanone, 3-hexanone, diisobutyl ketone, methylcyclohexanone, acetophenone, methylacetophenone, propyl acetate, butyl acetate, isobutyl acetate, amyl acetate, butyl acetate, isoamyl acetate, propyl formate, butyl formate, isobutyl formate, amyl formate, isoamyl formate, methyl valerate ... The invention further comprises one or more combinations of methyl crotonate, ethyl crotonate, methyl propionate, ethyl propionate, ethyl 3-ethoxypropionate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, isobutyl lactate, amyl lactate, isoamyl lactate, methyl 2-hydroxyisobutyrate, ethyl 2-hydroxyisobutyrate, methyl benzoate, ethyl benzoate, phenyl acetate, benzyl acetate, methyl phenylacetate, benzyl formate, phenylethyl formate, methyl 3-phenylpropionate, benzyl propionate, ethyl phenylacetate and 2-phenylethyl acetate.

[0068] Example

[0069] Resin (A)

[0070] Synthesis of monomer M1-1

[0071] 0.01 mol of 2-trifluoromethylphenol was added with excess SO3 and NaCl, and the reaction was carried out for 2 h. Subsequently, 0.01 mol of methacrylic acid and 0.012 mol of trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) were added to the system as a medium and reacted overnight under a nitrogen atmosphere. The solvent was then removed and the reaction was washed with ether. Then, 0.03 mol of a 50% aqueous solution of triphenylsulfide chloride was added and the reaction was carried out at room temperature overnight. The product was purified using dichloromethane and hexane to obtain monomer M1-1 in the form of colorless crystals with a yield of 63%. The synthesis method is shown in Equation (F1).

[0072]

[0073] Synthesis of monomer M1-2

[0074] 0.01 mol of 2,4-ditrifluoromethylphenol was added with excess SO3 and NaCl, and the reaction was carried out for 2 h. Subsequently, 0.01 mol of methacrylic acid and 0.012 mol of trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) were added to the system as media and reacted overnight under a nitrogen atmosphere. The solvent was then removed and the reaction was washed with ether. Then, 0.03 mol of a 50% aqueous solution of triphenylsulfide chloride was added and the reaction was carried out at room temperature overnight. The product was purified using dichloromethane and hexane to obtain monomer M1-2 in the form of colorless crystals with a yield of 55%. The synthesis method is shown in Equation (F2).

[0075]

[0076] Synthesis of monomers M1-3

[0077] 0.01 mol of sodium 2-nitrophenolsulfonate was added to 0.01 mol of methacrylic acid and 0.012 mol of trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) as a medium under a nitrogen atmosphere overnight. The solvent was then removed and the mixture was washed with ether. 0.03 mol of a 50% aqueous solution of triphenylsulfide chloride was added and reacted at room temperature overnight. The product was purified using dichloromethane and hexane to obtain monomer M1-3 in the form of colorless crystals with a yield of 51%. The synthesis method is shown in Equation (F3).

[0078]

[0079] Synthesis of monomers M1-4

[0080] 0.01 mol of 2-methylphenol was added with excess SO3 and NaCl, and the reaction was carried out for 2 h. Subsequently, 0.01 mol of methacrylic acid and 0.012 mol of trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) were added to the system as a medium and reacted overnight under a nitrogen atmosphere. The solvent was then removed and the reaction was washed with ether. Then, 0.03 mol of a 50% aqueous solution of triphenylsulfide chloride was added and the reaction was carried out at room temperature overnight. The product was purified using dichloromethane and hexane to obtain monomer M1-4 in the form of colorless crystals with a yield of 66%. The synthesis method is shown in Equation (F4).

[0081]

[0082] Synthesis of monomers M1-5

[0083] 0.01 mol of phenol was added with excess SO3 and NaCl, and the reaction was continued for 2 h. Subsequently, 0.01 mol of methacrylic acid and 0.012 mol of trifluoroacetic acid (TFA) and trifluoroacetic anhydride (TFAA) were added to the system as media under a nitrogen atmosphere overnight. The solvent was then removed and washed with ether. Then, 0.03 mol of a 50% aqueous solution of triphenylsulfide chloride was added and the reaction was continued at room temperature overnight. The product was purified using dichloromethane and hexane to obtain monomer M1-5 in the form of colorless crystals with a yield of 70%. The synthesis method is shown in Equation (F5).

[0084]

[0085] Monomers M2-1 to M2-4 are conventional commercially available monomers in the art, and their specific structures are shown in Table 1:

[0086] Table 1

[0087]

[0088] Synthesis example 1

[0089] Synthesis of Resin A-1

[0090] Monomers M1-1 0.5 mol, M2-1 3 mol, M2-2 5 mol, and M2-3 60 mol were selected, and THF / CH3CN was added under AIBN and fully polymerized for 3 h to obtain resin A-1. The measured molecular weight of A-1 was 3500 and the PDI was 2.1.

[0091] Synthesis Examples 2 to 8

[0092] Synthesis of Resins A2-8

[0093] The specific synthesis method is similar to that of Synthesis Example 1. The only difference is the selection of monomers. The specific formula, PDI and molecular weight are shown in Table 2. The weight average molecular weight Mw converted to polystyrene standard by GPC measurement is used. 13 C-NMR was used to determine the molar percentage of M1-X in the copolymerization ratio.

[0094] Table 2

[0095]

[0096] Examples 1 to 6 and Comparative Examples 1 and 2

[0097] The components shown in Table 3 were mixed and dissolved to prepare resist compositions of respective examples.

[0098] Table 3

[0099]

[0100] B-1 to B-3 are compounds represented by the following chemical formula:

[0101]

[0102] C-1 represents malic acid;

[0103] D-1 represents propylene glycol monomethyl ether;

[0104] D-2 represents propylene glycol monomethyl ether acetate;

[0105] Resist pattern formation

[0106] On an 8-inch silicon wafer treated with hexamethyldisilazane (HMDS) at 110°C for 60 seconds, a spin coater was used to apply the resist composition of each example. A pre-bake (PAB) process was performed at 150°C for 90 seconds on a hot plate and dried to form a resist film with a film thickness of 15 μm. Next, a KrF excimer laser (248 nm) was selectively irradiated to the resist film via a mask pattern (binary mask) using a KrF exposure device NSR-S203B (Nikon Corporation; NA (numerical aperture) = 0.60, σ = 0.68). Then, a post-exposure heating (PEB) process was performed at 110°C for 90 seconds. Next, an alkaline development was performed using a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution "NMD-3" (trade name, Tokyo Ohka Kogyo Co., Ltd.) as a developer at 23°C for 60 seconds. Thereafter, post-baking was performed at 100° C. for 60 seconds. As a result, an isolated space pattern with a space width of 5 μm was formed.

[0107] Resolution evaluation

[0108] The optimal exposure dose Eop (μC / cm2) for forming a 5 μm isolated space pattern in the above-mentioned resist pattern formation was determined. 2 ). Furthermore, a 3 μm isolated space pattern was formed in the same manner as in the formation of the resist pattern using the optimal exposure amount Eop as the exposure amount. The pattern shape of the 3 μm isolated space pattern was observed using a scanning electron microscope S-9380 (manufactured by Hitachi High-Technologies Corporation) and evaluated based on the following evaluation criteria.

[0109] Crack resistance evaluation

[0110] The silicon wafer with the isolated spacer pattern formed by the above-mentioned resist pattern formation was placed in the chamber of a scanning electron microscope S-9380 (manufactured by Hitachi High-Technologies Corporation) and vacuum treated for 60 seconds at a pressure of 0.0001 Pa. The vacuum-treated silicon wafer was observed using an optical microscope, and the number of cracks was counted. The crack count was evaluated based on the following evaluation criteria.

[0111] Evaluation of surface roughness after etching

[0112] The isolated spacer pattern formed using the resist pattern formation method described above was dry-etched using an etching apparatus manufactured by Tokyo Ohka Kogyo under the following conditions. Etching gas type and flow rate: a mixture of 30 cc / min of tetrafluoromethane, 30 cc / min of trifluoromethane, and 100 cc / min of helium; pressure: 300 mmTorr; power: 600 W; time: 120 seconds. A cross-section of the isolated spacer pattern after dry etching was observed using a scanning electron microscope (product name: S4500; manufactured by Hitachi High-Technologies Corporation) to visually evaluate the presence of surface roughness in the pattern cross-section.

[0113] The specific evaluation results are shown in Table 4

[0114] Table 4

[0115] Serial number Resolution Number of cracks Rough or not Example 1 Excellent - Patterns are reliably formed onto the substrate 4 smooth Example 2 Excellent - Patterns are reliably formed onto the substrate 0 smooth Example 3 Excellent - Patterns are reliably formed onto the substrate 1 smooth Example 4 General-with curling 3 A small amount of roughness Example 5 Excellent - Patterns are reliably formed onto the substrate 5 A small amount of roughness Example 6 General-with curling 1 A small amount of roughness Comparative Example 1 Poor - unable to form a pattern 7 Noticeably rough Comparative Example 2 General-with curling 10 Noticeably rough

[0116] It should be noted that, based on the explanations and elaborations of the above description, those skilled in the art may make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and equivalent modifications and variations of the present invention should also fall within the scope of protection of the claims of the present invention. Furthermore, although certain specific terms are used in this description, these terms are for convenience only and do not constitute any limitation to the invention.

Claims

1. A resist composition that generates acid upon exposure and whose solubility in a developer changes due to the action of the acid, characterized in that: Contains a resin (A), an acid diffusion inhibitor (B), an additive (C) and a solvent (D); The resin (A) comprises a structural unit represented by the general formula (1): In the general formula (1), R1 represents a monovalent organic group, including but not limited to an alkyl group having 1 to 4 carbon atoms, an alkoxy group, an alkenyl group, a phenyl group, a halogen atom, a halogen-substituted or polysubstituted alkyl group, an alkoxy group, an alkenyl group having 1 to 4 carbon atoms, and a nitro group, or one or more combinations thereof; wherein m is a positive integer and is between 1 and 3; R2 represents a monovalent organic group, including but not limited to an alkyl group having 1 to 4 carbon atoms, a phenyl group, a phenyl group having 1 to 4 carbon atoms, or one or more combinations thereof; wherein n is a positive integer and is between 1 and 3.

2. The resist composition according to claim 1, wherein In the general formula (1), R1 includes one or more combinations of methyl, trifluoromethyl, and nitro, wherein m is 1 or 2; R2 in the general formula (1) includes one or more combinations of phenyl, p-methylphenyl, p-ethylphenyl, p-propylphenyl, p-butylphenyl, and p-tert-butylphenyl, wherein n is 2 or 3.

3. The resist composition according to any one of claims 1 to 2, characterized in that The general formula (1) comprises one or more combinations of the structural units shown in the chemical formula (2), wherein Ph represents a phenyl group:

4. The resist composition according to any one of claims 1 to 3, wherein The molar percentage of the structural unit represented by the general formula (1) in the resin (A) is between 5 mol% and 10 mol%. Preferably, the molar percentage of the structural unit represented by the general formula (1) in the resin (A) is between 6.2 mol% and 7 mol%.

5. The resist composition according to claim 1, wherein The resin (A) comprises one or more combinations of methacrylate structural units containing a cycloalkane structure as shown in chemical formula (3):

6. The resist composition according to claim 1, wherein The resin (A) comprises one or more combinations of aromatic vinyl structural units containing or not containing hydroxyl groups as shown in chemical formula (4):

7. The resist composition according to claim 1, wherein The resin (A) comprises one or more combinations of aromatic methacrylate structural units containing or not containing hydroxyl groups as shown in chemical formula (5):

8. The resist composition according to claim 1, wherein The resist composition comprises an acid diffusion inhibitor (B), and the acid diffusion inhibitor (B) comprises one or more combinations of the following compounds: n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, dialkylamine, di-n-heptylamine, di-n-octylamine, dicyclohexylamine, trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-nonylamine, tri-n-decylamine, n-dodecylamine, diethanolamine, triethanolamine, diisopropanolamine, trialkylamine, isopropanolamine, di-n-octanolamine, and tri-n-octanolamine; preferably, the acid diffusion inhibitor (B) comprises one of tri-n-pentylamine or tri-n-octylamine.

9. The resist composition according to claim 1, wherein The resist composition comprises an additive (C), which is one or more combinations of organic carboxylic acids or oxygen-containing phosphoric acids and their derivatives; preferably, the additive comprises one or more combinations of acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, phosphoric acid, phosphonic acid, and phosphinic acid.

10. A pattern forming method, characterized in that: The pattern forming method includes the steps of coating the resist composition described in any one of claims 1 to 9 on a substrate; after performing a heat treatment before exposure, exposing the substrate through a photomask using any one of high-energy rays, electron beams or extreme ultraviolet light with a wavelength of 140 to 250 nm; and after the exposure and heat treatment, developing the substrate using a developer; using an alkaline aqueous solution or an organic solvent as a developer to dissolve the exposed or unexposed part, thereby obtaining a positive or negative pattern.

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