Stable chemically amplified positive photoresist and preparation and use methods thereof

Abstract

The invention provides a stable chemical amplification type positive photoresist. The photoresist comprises the following components in percentage by mass: 20-40% of polymer resin, 0.4-2.4% of a photoacid generator, 3-20% of an acid diffusion control agent, 0.01-0.5% of a flatting agent and the balance of a solvent, the preparation method of the polymer resin comprises the following steps: dissolving a hydroxystyrene compound, a styrene compound and a tert-butyl acrylate compound in an alcohol solvent, then adding an initiator dimethyl azodiisobutyrate, carrying out a polymerization reaction, and carrying out solid resin post-treatment on a polymerization reaction product; the solvent is propylene glycol monomethyl ether acetate as a main solvent and an auxiliary solvent, and the auxiliary solvent is one or more of ethyl lactate, gamma-butyrolactone and methyl isobutyl ketone. After the chemically amplified positive photoresist disclosed by the invention is aged for 5 days at a high temperature (40 DEG C), the energy descending rate is less than 5%, and the photoresist has excellent stability.

Description

Technical Field

[0001] The invention belongs to the technical field of photoresists, and in particular relates to a stable chemically amplified positive photoresist and a preparation and use method thereof. Background Art

[0002] Photoresist is a key material for manufacturing integrated circuits, and its performance directly affects the integration, operating speed, power consumption and other performance of the integrated circuit chip.

[0003] Photoresist, also known as photoresist, is a photosensitive polymer material with high sensitivity to light and radiation. After being irradiated or radiated by ultraviolet light, electron beam, excimer laser beam, ion beam, X-ray, etc., it can undergo photochemical reactions, causing the dissolution properties of the film to change before and after exposure. Therefore, it can be divided into positive photoresist and negative photoresist. Compared with negative photoresist, positive photoresist has better resolution and photosensitivity, especially chemically amplified positive photoresist, which has become the mainstream photoresist for high-density and large-scale integrated circuit manufacturing. Chemically amplified positive photoresist is mainly composed of film-forming resin, photoacid generator, acid diffusion controller, leveling agent, other additives and solvents. Precisely because of its excellent photosensitivity, in practical applications, chemically amplified positive photoresists are prone to energy instability. For example, some acid diffusion controllers in the photoresist components can easily cause the decomposition of the photoacid generator (photoacid) and cause energy changes; residual alcohol compounds in the film-forming resin can react with the photoacid generator; residual cyano structures in the film-forming resin are easily hydrolyzed into amides or carboxylic acids that can react with the photoacid generator, thereby affecting the energy stability of the photoresist. Summary of the invention

[0004] In order to solve the problems in the prior art, the present invention provides a stable chemically amplified positive photoresist and a preparation and use method thereof.

[0005] The specific technical solutions of the present invention are as follows:

[0006] The stable chemically amplified positive photoresist provided by the present invention is characterized in that the photoresist comprises the following components in percentage by mass: 20-40% of polymer resin, 0.4-2.4% of photoacid generator, 3-20% of acid diffusion controller, 0.01-0.5% of leveling agent, and the remainder of solvent;

[0007] The preparation method of the polymer resin comprises the following steps: dissolving a hydroxystyrene compound, a styrene compound and a tert-butyl acrylate compound in an alcohol solvent, adding an initiator dimethyl azobisisobutyrate to carry out polymerization reaction, and carrying out solid resin post-treatment on the polymerization reaction product.

[0008] The stable chemically amplified positive photoresist provided by the present invention also has the following technical features: the polymer resin is composed of a hydroxystyrene compound, a styrene compound and a tert-butyl acrylate compound, and the molar percentages of the hydroxystyrene compound, the styrene compound and the tert-butyl acrylate compound are: 55-65% of the hydroxystyrene compound, 15-25% of the styrene compound, and 15-25% of the tert-butyl acrylate compound;

[0009] The stable chemically amplified positive photoresist provided by the present invention also has the following technical features: the weight average molecular weight of the polymer resin is 12-27k, and the molecular weight distribution coefficient is PDI<2.5.

[0010] The stable chemically amplified positive photoresist provided by the present invention also has the following technical features: the solvent is a main solvent of propylene glycol monomethyl ether acetate and an auxiliary solvent, and the auxiliary solvent is one or more of ethyl lactate, γ-butyrolactone, and methyl isobutyl ketone.

[0011] The stable chemically amplified positive photoresist provided by the present invention also has the following technical feature: the mass percentage of the auxiliary solvent in the solvent is 5-20%.

[0012] The stable chemically amplified positive photoresist provided by the present invention also has such a technical feature, wherein the photoacid generator is selected from one or more of the following structural formulas:

[0013]

[0014]

[0015] The stable chemically amplified positive photoresist provided by the present invention also has such technical characteristics, wherein, the acid diffusion control agent is selected from one or more of triethylenediamine, tri(3,6-dioxaheptyl)amine, triisopropanolamine, 2-ethyl-N,N-bis(2-ethylhexyl)-1-hexylamine, 2,6-di-tert-butylpyridine, 1-(tert-butoxycarbonyl)-4-hydroxypiperidine, 2-phenylbenzimidazole or diphenylamine;

[0016] The leveling agent is selected from one or more of surfactant FTX-218, leveling agent EFS-801, leveling agent F-554, leveling agent F-563, leveling agent HX-3110 and leveling agent HX-3390.

[0017] The present invention also provides a method for preparing the above-mentioned stable chemically amplified positive photoresist, which is characterized by comprising the following steps: uniformly mixing a polymer resin, a photoacid generator, an acid diffusion controller, a leveling agent, and a solvent according to mass percentage, and filtering through a 0.45μm+0.22μm PTFE capsule filter to obtain the resultant.

[0018] The present invention also provides a method for using the above-mentioned stable chemically amplified positive photoresist, which is characterized by comprising the following steps: spin coating the photoresist on a silicon wafer, and sequentially performing pre-baking, exposure, post-baking and development to obtain a photolithography pattern.

[0019] The method for using the above-mentioned stable chemically amplified positive photoresist provided by the present invention also has the following technical features, wherein the spin coating rotation speed is 1000-3000 rpm; the pre-baking temperature is 110-150°C, and the pre-baking time is 70-110s; the exposure is performed using an I-12 exposure machine; the post-baking temperature is 110-150°C, and the post-baking time is 70-110s; and the developing solution used for development is TMAH.

[0020] Functions and Effects of the Invention

[0021] Compared with the prior art, the technical advantages of the present invention are as follows:

[0022] (1) The component polymer resin used in the stable chemically amplified positive photoresist of the present invention is a copolymer of a hydroxystyrene compound, a styrene compound and a tert-butyl acrylate compound. In the polymerization reaction, the initiator is dimethyl azobisisobutyrate (V601). Compared with azobisisobutyronitrile (V60), the advantage of this initiator is that when the V60 initiator is used, the cyano structure remaining in the polymer resin is easily hydrolyzed into amide or carboxylic acid, and both amide and carboxylic acid can react with a photoacid generator to affect the energy stability of the photoresist, while the V601 initiator will not introduce a cyano structure.

[0023] (2) The solid resin post-treatment process is used in the preparation method of the component polymer resin. Compared with the liquid resin post-treatment process, the advantages of this process are: when the liquid resin post-treatment process is used, the methanol residue in the obtained polymer resin is relatively large (>1000ppm). When the solid resin post-treatment process is used, the methanol residue in the obtained polymer resin is relatively small (≤100ppm). Alcohol compounds such as methanol and ethanol can react with sulfur-containing ionic photoacids to destroy the structure of such photoacids, thereby causing energy instability of the photoresist.

[0024] (3) The solvent used in the stable chemically amplified positive photoresist of the present invention is a main solvent of propylene glycol monomethyl ether acetate + an auxiliary solvent with excellent solubility (one or more of ethyl lactate, γ-butyrolactone, and methyl isobutyl ketone). The auxiliary solvent itself has a large dipole moment, which makes the photoacid more easily dissociated, and the solubility and stability of the photoacid are better.

[0025] In summary, the energy downlink of the stable chemically amplified positive photoresist of the present invention is less than 5% after aging at high temperature (40° C.) for 5 days, and the photoresist has excellent stability. DETAILED DESCRIPTION

[0026] The terms used in the present invention, unless otherwise specified, generally have the meanings that are commonly understood by those of ordinary skill in the art.

[0027] In the following examples, various processes and methods not described in detail are conventional methods well known in the art.

[0028] The reagents used in the following examples were purchased from common commercial sources, and the experimental operations and experimental conditions not specified were referred to the conventional operations and conventional conditions in the art.

[0029] The specific implementation of the present invention is described below with reference to embodiments.

[0030] <Example 1>

[0031] This embodiment provides a method for preparing a polymer resin, specifically, synthesizing a poly(p-hydroxystyrene) polymer A-β1, and the synthesis route thereof is as follows:

[0032] In a 500mL dry four-necked flask protected by nitrogen equipped with a stirrer and a condenser, acetoxystyrene (90.0g, 0.555mol), styrene (19.3g, 0.185mol), tert-butyl acrylate (23.7g, 0.185mol) and solvent methanol (140g) were added. The reaction system was decompressed and evacuated, and nitrogen was replaced three times. The reaction solution was stirred and mixed, cooled to 0°C, and then initiator V601 (5.6g) was added. Stir for 10min, the reaction system was heated to 65°C, and the reaction was reacted for 18h. After the polymerization was complete, the reaction system was cooled to room temperature.

[0033] The system device was changed into a distillation device, methanol (150 g) was added to dilute the system, and then 26% sodium methoxide solution (1.5 g) was added dropwise. The system was heated to 62-65°C and reacted for 8 hours. During this process, the acetyl group in acetoxystyrene was removed to form a hydroxyl group. Methanol (150 g) was added to dilute the system, and then the mixed solution was slowly passed through an A15 cation exchange resin column to remove the metal ions in the mixed solution. Then, solvent replacement was performed, and methanol was replaced with propylene glycol methyl ether acetate to obtain a finished polymer resin solution (355.28 g, solid content 36.169 wt%), i.e., 4-hydroxystyrene-styrene-butyl acrylate terpolymer A-β1 (weight average molecular weight 24.1k, molecular weight distribution coefficient 2.31, methanol residual 2000 ppm) solution.

[0034] <Example 2>

[0035] This embodiment provides a method for preparing a polymer resin, specifically, synthesizing a poly(p-hydroxystyrene) polymer A-β2, and the synthesis route thereof is as follows:

[0036] In a 500mL dry four-necked flask protected by nitrogen equipped with a stirrer and a condenser, acetoxystyrene (90.0g, 0.555mol), styrene (19.3g, 0.185mol), tert-butyl acrylate (23.7g, 0.185mol) and solvent methanol (140g) were added. The reaction system was decompressed and evacuated, and then replaced with nitrogen three times. The reaction solution was stirred and mixed, cooled to 0°C, and then the initiator azobisisobutyronitrile (4g) was added and stirred for 10min. The reaction system was heated to 65°C and reacted for 18h. After the polymerization was complete, the reaction system was cooled to room temperature.

[0037] The system device was changed into a distillation device, methanol (150g) was added to dilute the system, and 26% sodium methoxide solution (1.5g) was added dropwise, the system was heated to 62-65°C, and after reacting for 8h, the mixed solution was slowly added dropwise to 5L of deionized water to precipitate to obtain a solid compound, which was collected by 40# filter paper, and the solid compound was dissolved to about 20% with methanol, and the compound was precipitated in 5L of deionized water again, and the above operation was repeated three times. The solid compound was collected and placed in a 45°C vacuum oven to dry for 48h to obtain 4-hydroxystyrene-styrene-butyl acrylate terpolymer A-β2 (120.7g, weight average molecular weight 23.9K, molecular weight distribution coefficient 1.78, methanol residual 100ppm).

[0038] <Example 3>

[0039] This embodiment provides a method for preparing a polymer resin, specifically, synthesizing a poly(p-hydroxystyrene) polymer A-β3, and the synthesis route thereof is as follows:

[0040] In a 500mL dry four-necked flask protected by nitrogen equipped with a stirrer and a condenser, acetoxystyrene (90.0g, 0.555mol), styrene (19.3g, 0.185mol), tert-butyl acrylate (23.7g, 0.185mol) and solvent methanol (140g) were added. The reaction system was decompressed and evacuated, and nitrogen was replaced three times. The reaction solution was stirred and mixed, cooled to 0°C, and then initiator V601 (5.6g) was added. Stir for 10min, the reaction system was heated to 65°C, and the reaction was reacted for 18h. After the polymerization was complete, the reaction system was cooled to room temperature.

[0041] The system device was changed into a distillation device, methanol (150g) was added to dilute the system, and 26% sodium methoxide solution (1.5g) was added dropwise, the system was heated to 62-65°C, and after reacting for 8h, the mixed solution was slowly added dropwise to 5L of deionized water to precipitate to obtain a solid compound, which was collected by 40# filter paper, and the solid compound was dissolved to about 20% with methanol, and the compound was precipitated in 5L of deionized water again, and the above operation was repeated three times. The solid compound was collected and placed in a vacuum oven at 45°C for 48h to obtain 4-hydroxystyrene-styrene-butyl acrylate terpolymer A-β3 (122.4g, weight average molecular weight 23.8K, molecular weight distribution coefficient 1.75, methanol residual 80ppm).

[0042] <Comparative Example 1>

[0043] This comparative example provides a method for preparing a polymer resin, specifically relates to the synthesis of poly(p-hydroxystyrene) polymer A-α, and the synthesis route thereof is as follows:

[0044] In a 500mL dry four-necked flask protected by nitrogen equipped with a stirrer and a condenser, acetoxystyrene (90.0g, 0.555mol), styrene (19.3g, 0.185mol), tert-butyl acrylate (23.7g, 0.185mol) and solvent methanol (140g) were added. The reaction system was decompressed and evacuated, and then replaced with nitrogen three times. The reaction solution was stirred and mixed, cooled to 0°C, and then the initiator azobisisobutyronitrile (4g) was added and stirred for 10min. The reaction system was heated to 65°C and reacted for 18h. After the polymerization was complete, the reaction system was cooled to room temperature.

[0045] The system device was changed into a distillation device, methanol (150 g) was added to dilute the system, and then 26% sodium methoxide solution (1.5 g) was added dropwise. The system was heated to 62-65°C and reacted for 8 hours. During this process, the acetyl group in acetoxystyrene was removed to form a hydroxyl group. Methanol (150 g) was added to dilute the system, and then the mixed solution was slowly passed through an A15 cation exchange resin column to remove the metal ions in the mixed solution. Then solvent replacement was performed, and methanol was replaced with propylene glycol methyl ether acetate to obtain a finished polymer resin solution (369.46 g, solid content 34.997 wt%), i.e., 4-hydroxystyrene-styrene-butyl acrylate terpolymer A-α (weight average molecular weight 24.3k, molecular weight distribution coefficient 2.32, methanol residual 2020 ppm) solution.

[0046] <Examples 4-7>, <Comparative Example 2>

[0047] The polymer resin or polymer resin solution prepared in the above Examples 1-3 and Comparative Example 1 was used to prepare a chemically amplified positive photoresist. The contents of the components of the photoresist are listed in Table 1.

[0048] Preparation method of photoresist: add the components according to Table 1, mix and stir evenly, and filter through a 0.45μm+0.22μm PTFE capsule filter to obtain the photoresist.

[0049] Table 1

[0050]

[0051]

[0052] <Test example>

[0053] Each prepared photoresist is aged. Taking the photoresist prepared in Comparative Example 2 as an example, the aging process is as follows:

[0054] The samples were packaged into three small pieces and placed in different environments for aging comparison tests. The environments were 20-25℃ for 5 days, 0-10℃ for 5 days, and 45℃ for 5 days.

[0055] After aging, the photoresists prepared in Comparative Example 2 and Examples 4 to 7 were used in the following manner:

[0056] The aged photoresist was spin-coated at 1000-3000 rpm on an 8-inch bare silicon wafer with HDMS primer to form a 3 μm film. The film was pre-baked on a 130°C hot plate for 90 seconds, and then selectively exposed (800nm ​​Line / Space) using an I-12 exposure machine (Conventional: NA0.57Sigma 0.67), and then post-baked on a 130°C hot plate for 90 seconds. After the wafer was cooled to room temperature, it was developed with a 2.38% TMAH developer for 60 seconds, and finally rinsed with deionized water for 30 seconds to form the desired photolithography pattern.

[0057] The photolithography data of the photoresists prepared in Comparative Example 2 and Examples 4 to 7 after aging are listed in Tables 2 to 6 respectively.

[0058] Table 2

[0059]

[0060] Table 3

[0061]

[0062] Table 4

[0063]

[0064] Table 5

[0065]

[0066]

[0067] Table 6

[0068]

[0069] As shown in Tables 2 to 6, the energy of the photoresist prepared in Comparative Example 2 is seriously decreased after 5 days of high temperature aging, and the energy of the photoresists prepared in Examples 4 to 7 is gradually decreased after 5 days of high temperature aging, and the photoresist prepared in Example 7 has the best stability. The results show that the use of initiator V601 and solid resin post-treatment process in the preparation process of the polymer resin component of the photoresist, and the use of a mixed form of the main solvent propylene glycol monomethyl ether acetate + an auxiliary solvent with excellent solubility as the photoresist solvent can effectively improve the stability of the chemically amplified positive photoresist.

[0070] The above is a detailed description of the embodiments, which is convenient for those skilled in the art to correctly understand and use the present invention. Any improvements or modifications to the technical solutions obtained by those skilled in the art based on the present invention on the basis of the prior art, without innovative work, only through analysis, analogy or limited enumeration, etc., should be within the scope of protection determined by the claims.

Claims

1. A stable chemically amplified positive photoresist, characterized in that: The photoresist comprises the following components in percentage by mass: The preparation method of the polymer resin comprises: dissolving a hydroxystyrene compound, a styrene compound and a tert-butyl acrylate compound in an alcohol solvent, adding an initiator dimethyl azobisisobutyrate to carry out a polymerization reaction, and carrying out a solid resin post-treatment on the polymerization reaction product.

2. The stable chemically amplified positive photoresist according to claim 1, characterized in that: in, The polymer resin is composed of a hydroxystyrene compound, a styrene compound and a tert-butyl acrylate compound, and the molar percentages of the hydroxystyrene compound, the styrene compound and the tert-butyl acrylate compound are: Hydroxystyrene compounds 55-65%, Styrene compounds 15-25%, Tert-butyl acrylate compound 15-25%.

3. The stable chemically amplified positive photoresist according to claim 2, characterized in that: in, The weight average molecular weight of the polymer resin is 12-27k, and the molecular weight distribution coefficient is PDI<2.

5.

4. The stable chemically amplified positive photoresist according to claim 1, characterized in that: in, The solvent is mainly propylene glycol monomethyl ether acetate and an auxiliary solvent. The auxiliary solvent is one or more of ethyl lactate, gamma-butyrolactone and methyl isobutyl ketone.

5. The stable chemically amplified positive photoresist according to claim 4, characterized in that: in, The auxiliary solvent accounts for 5-20% of the solvent by mass.

6. The stable chemically amplified positive photoresist according to claim 1, characterized in that: in, The photoacid generator is selected from one or more of the following structural formulas:

7. The stable chemically amplified positive photoresist according to claim 1, characterized in that: in, The acid diffusion control agent is selected from one or more of triethylenediamine, tri(3,6-dioxaheptyl)amine, triisopropanolamine, 2-ethyl-N,N-bis(2-ethylhexyl)-1-hexylamine, 2,6-di-tert-butylpyridine, 1-(tert-butoxycarbonyl)-4-hydroxypiperidine, 2-phenylbenzimidazole or diphenylamine; The leveling agent is selected from one or more of surfactant FTX-218, leveling agent EFS-801, leveling agent F-554, leveling agent F-563, leveling agent HX-3110 and leveling agent HX-3390.

8. A method for preparing a stable chemically amplified positive photoresist as claimed in any one of claims 1 to 7, characterized in that: The method comprises the following steps: uniformly mixing the polymer resin, the photoacid generator, the acid diffusion controller, the leveling agent and the solvent according to mass percentage, and filtering the mixture through a 0.45 μm+0.22 μm PTFE capsule filter to obtain the mixture.

9. A method for using the stable chemically amplified positive photoresist according to any one of claims 1 to 7, characterized in that: The following steps are involved: The photoresist is spin-coated on a silicon wafer, and sequentially subjected to pre-baking, exposure, post-baking and development to obtain a photolithographic pattern.

10. The method for using the stable chemically amplified positive photoresist according to claim 9, characterized in that: in, The rotation speed of the spin coating is 1000-3000 rpm; The pre-baking temperature is 110-150°C, and the pre-baking time is 70-110s; The exposure adopts I-12 exposure machine; The post-baking temperature is 110-150°C, and the post-baking time is 70-110s; The developer used in the development is TMAH.

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