193nm photoresist resin and method for preparing the same

Abstract

The present application relates to a kind of 193nm photoresist resin, when preparing the resin: by etching-resistant methacrylate and carbamate-containing methacrylate in free radical thermal initiator and solvent is made by thermal polymerization.The preparation method of this kind of 193nm photoresist resin includes monomer thermal polymerization, precipitation-dissolution purification and metal impurity filtration.The present application introduces the methacrylate containing carbamate group in the resin synthesis, utilizes its weak alkaline neutralization photoacid diffusion, improves exposure edge definition, and because monomer is polymerized to resin chain, avoid volatilization;Metal impurity content is controlled simultaneously by purification process.The resin has high etching resistance, low metal impurity and excellent edge definition, solves the technical problems that etching precision is reduced due to acid diffusion of traditional photoresist and organic amine volatilization pollutes equipment.

Description

Technical Field

[0001] This invention belongs to the field of photoresist technology, and particularly relates to a 193nm photoresist resin and its preparation method. Background Technology

[0002] Polymethyl methacrylate resin is used as a film-forming resin in semiconductor photoresist compositions due to its good light transmittance and excellent etching resistance. 193nm photoresist uses a light source with a wavelength of 193nm. Since benzene rings have strong absorption in this wavelength range (which competes with photoacid generators for light absorption), 193nm photoresist resin cannot use monomers containing benzene rings. Instead, it needs to use rigid groups such as cyclic structures to maintain etching resistance.

[0003] 193nm photoresist is used under high vacuum. Unreacted impurities and monomers are volatile and can contaminate the exposure equipment, so they must be completely removed. High-precision integrated circuits have stringent requirements for the metal impurity content of photoresist, requiring that the content of single metal impurities in the film-forming resin be <1ppb and the total metal impurity content be <10ppb.

[0004] In photolithography processes requiring high etching precision, conventional 193nm resin, after preparation, needs to be mixed with other resins, photoacid generators (0.5%–2%), additives, and solvents to form a photoresist solution. The photoacid generator produces a super-strong protic acid under illumination, which acidifies the acid-soluble groups in the resin to improve alkali solubility and achieve a difference in solubility between the exposed and non-exposed areas. However, after decomposition, the photoacid diffuses within the film, leading to a decrease in the precision of the boundary between the exposed and non-exposed areas. Existing technologies use a small amount of organic amine to neutralize the diffusing acid and suppress this side effect; however, in the pre-lithography processes (coating, baking, exposure, development, and post-baking), the small molecules of organic amine are easily volatile, affecting the photolithography equipment and the environment.

[0005] Therefore, existing 193nm photoresist resins have technical defects such as high requirements for controlling metal impurities, reduced etching accuracy due to photo-generated acid diffusion, and pollution of equipment by volatile organic amines. New resin systems need to be developed to solve these problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a 193nm photoresist resin and its preparation method.

[0007] This 193nm photoresist resin is thermally polymerized in a solvent in the presence of a free radical thermal initiator in the following parts by weight:

[0008] 99.9–99.97 parts of etching-resistant methacrylate.

[0009] 0.03–0.1 parts of urethane-containing methacrylates; wherein,

[0010] The free radical thermal initiator is in the form of 2 to 8 parts by mass, and the solvent is in the form of 100 to 300 parts by mass.

[0011] Preferably, the etching-resistant methacrylate is at least one of the following:

[0012] 1-Methylcyclopentyl methacrylate, 1-ethylcyclopentyl methacrylate, 1-isopropylcyclopentyl methacrylate, 1-methylcyclohexyl methacrylate, 1-ethylcyclohexyl methacrylate, 1-isopropylcyclohexyl methacrylate, 2-methyl-2-adamantaneol methacrylate, 2-ethyl-2-adamantaneol methacrylate, 1-(1-adamantane)-1-methylethyl methacrylate, 2-isopropyl-2-adamantaneol methacrylate, 3-hydroxy-1-adamantaneol methacrylate, 2-carboxy-4-norbornolide-5-methacrylate, 2-carboxy-4-norbornolide-5-acetoxymethacrylate.

[0013] Preferably, the etching-resistant methacrylates are 3 to 8 of the following:

[0014] 1-Methylcyclopentyl methacrylate, 1-ethylcyclopentyl methacrylate, 1-isopropylcyclopentyl methacrylate, 1-methylcyclohexyl methacrylate, 1-ethylcyclohexyl methacrylate, 1-isopropylcyclohexyl methacrylate, 2-methyl-2-adamantaneol methacrylate, 2-ethyl-2-adamantaneol methacrylate, 1-(1-adamantane)-1-methylethyl methacrylate, 2-isopropyl-2-adamantaneol methacrylate, 3-hydroxy-1-adamantaneol methacrylate, 2-carboxy-4-norbornolide-5-methacrylate, 2-carboxy-4-norbornolide-5-acetoxymethacrylate.

[0015] Preferably, the methacrylate containing the carbamate is any one of the following: ethyl carbamate-2-methyl-2-adamantane methacrylate, ethyl carbamate-2-isopropyl-2-adamantane methacrylate, or ethyl carbamate-2-ethyl-2-adamantane methacrylate.

[0016] Preferably, the free radical thermal initiator is an azo thermal initiator or a peroxide thermal initiator; the azo thermal initiator includes azobisisobutyronitrile and dimethyl azobisisobutyrate; the peroxide thermal initiator is benzoyl peroxide.

[0017] Preferably, the solvent is at least one of the following electronic-grade solvents: ethyl acetate, propylene glycol methyl ether acetate, and cyclohexanone.

[0018] The preparation method of this 193nm photoresist resin includes the following steps:

[0019] Weigh out the above-mentioned parts by weight of etch-resistant methacrylate, urethane-containing methacrylate, free radical thermal initiator and solvent, and allow the above components to undergo free radical thermal polymerization at 60-100°C to obtain a 193nm photoresist resin solution.

[0020] Preferably, the following purification steps are also included:

[0021] Impurities and unreacted components in the 193nm photoresist resin solution obtained by the thermal polymerization reaction were removed by precipitation-dissolution technology to obtain a pure 193nm photoresist resin solution.

[0022] Metal impurities in the pure 193nm photoresist resin solution were removed by filtration to obtain an ultrapure 193nm photoresist resin solution.

[0023] As a preferred option, the purification steps are as follows:

[0024] Impurities and unreacted components in the 193nm photoresist resin solution obtained by thermal polymerization are removed using a precipitation-dissolution technique: A precipitant is added to the solution containing the 193nm photoresist resin obtained by thermal polymerization, with the amount of precipitant added being 2 to 4 times that of the 193nm photoresist resin solution. Resin precipitate is precipitated under stirring conditions. The precipitated resin is separated from the liquid phase and vacuum dried to obtain solid resin. The solid resin is redissolved with a solvent. The above steps are repeated 3 to 5 times to obtain a pure 193nm photoresist resin solution.

[0025] Metal impurities in the pure 193nm photoresist resin solution are removed by column filtration or membrane filtration to obtain an ultrapure 193nm photoresist resin solution. The column packing material in the column filtration technology is polystyrene sulfonic acid resin; the membrane filtration technology uses a commercial metal ion removal filter membrane.

[0026] Preferably, the precipitant is at least one of the following electronic-grade precipitants: cyclohexane, n-hexane, n-heptane; and the solvent is at least one of the following electronic-grade solvents: ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate, cyclohexanone.

[0027] The beneficial effects of this invention are:

[0028] In this invention, urethane-containing methacrylates are introduced during the thermal polymerization synthesis of 193nm photoresist resin. Because the urethane groups are weakly basic, they can react with the generated acid during subsequent photolithography, thereby controlling the migration of acid to non-photolithographic areas and improving the edge sharpness of the photolithography. Since the amount of urethane-containing methacrylates added is small, it does not affect the reaction process in the photolithographic areas, nor does it affect the basic structure, etching resistance, or light transmittance of the resin. It also has minimal impact on sensitivity and exposure time. Furthermore, since the introduced urethane-containing methacrylates are synthesized on the resin, they will not volatilize later.

[0029] Since the urethane groups in the introduced urethane-containing methacrylates are weakly basic, urethane-containing methacrylates can be used to completely or partially replace amine additives in photoresist formulations to improve the edge clarity of photolithography. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0031] Example 1

[0032] A method for preparing a 193nm photoresist resin specifically includes the following steps:

[0033] Weigh the reactants, free radical thermal initiator, and solvent for free radical thermal polymerization according to the following mass proportions:

[0034] 99.9 parts of 1-ethylcyclopentyl methacrylate, 1-ethylcyclohexyl methacrylate, 2-methyl-2-adamantaneol methacrylate, 2-ethyl-2-adamantaneol methacrylate and 3-hydroxy-1-adamantaneol methacrylate.

[0035] 0.03 parts of ethyl carbamate-2-methyl-2-adamantane methacrylate.

[0036] Two parts of azobisisobutyronitrile (AIBN)

[0037] 100 parts of electronic grade ethyl acetate;

[0038] The above components undergo free radical thermal polymerization at 60°C to obtain a 193nm photoresist resin solution;

[0039] Impurities and unreacted components in the 193nm photoresist resin solution obtained by thermal polymerization were removed using a precipitation-dissolution technique: a precipitant (cyclohexane) was added to the solution containing the 193nm photoresist resin obtained by thermal polymerization, with the amount of precipitant added being twice the amount of the 193nm photoresist resin solution, and resin precipitate was precipitated under stirring conditions; the precipitated resin was separated from the liquid phase and vacuum dried to obtain solid resin; the solid resin was redissolved with a solvent (electronic grade ethylene glycol methyl ether acetate); the above steps were repeated 5 times to obtain a pure 193nm photoresist resin solution;

[0040] Metal impurities in the pure 193nm photoresist resin solution were removed by column filtration technology to obtain an ultrapure 193nm photoresist resin solution; the column packing material in the column filtration technology was polystyrene sulfonic acid resin.

[0041] Example 2

[0042] A method for preparing a 193nm photoresist resin specifically includes the following steps:

[0043] Weigh the reactants, free radical thermal initiator, and solvent for free radical thermal polymerization according to the following mass proportions:

[0044] 99.97 parts of 1-ethylcyclopentyl methacrylate, 1-isopropylcyclopentyl methacrylate, 1-methylcyclohexyl methacrylate, 2-carboxy-4-norbornolactone-5-methacrylate, and 2-carboxy-4-norbornolactone-5-acetoxymethacrylate.

[0045] 0.1 parts of 2-isopropyl-2-adamantane ethyl methacrylate.

[0046] Benzoyl peroxide 8 parts,

[0047] 300 parts of electronic grade propylene glycol methyl ether acetate;

[0048] The above components undergo free radical thermal polymerization at 100℃ to obtain a 193nm photoresist resin solution;

[0049] Impurities and unreacted components in the 193nm photoresist resin solution obtained by thermal polymerization were removed using a precipitation-dissolution technique: a precipitant (n-hexane) was added to the solution containing the 193nm photoresist resin obtained by thermal polymerization, with the amount of precipitant added being 4 times that of the 193nm photoresist resin solution, and resin precipitate was precipitated under stirring conditions; the precipitated resin was separated from the liquid phase and vacuum dried to obtain solid resin; the solid resin was redissolved with a solvent (electronic grade propylene glycol methyl ether acetate); the above steps were repeated 3 times to obtain a pure 193nm photoresist resin solution;

[0050] Metal impurities in the pure 193nm photoresist resin solution were removed by membrane filtration technology to obtain an ultrapure 193nm photoresist resin solution; the membrane filtration technology used was a commercial metal ion removal filter membrane.

[0051] Example 3

[0052] A method for preparing a 193nm photoresist resin specifically includes the following steps:

[0053] Weigh the reactants, free radical thermal initiator, and solvent for free radical thermal polymerization according to the following mass proportions:

[0054] 99.93 parts of 1-methylcyclohexyl methacrylate, 1-ethylcyclohexyl methacrylate, 1-isopropylcyclohexyl methacrylate, 2-methyl-2-adamantaneol methacrylate, 2-ethyl-2-adamantaneol methacrylate, and 1-(1-adamantane)-1-methylethyl methacrylate.

[0055] 0.07 parts of 2-ethyl-2-adamantane methacrylate,

[0056] 5 parts of dimethyl azobisisobutyrate

[0057] 200 parts of electronic grade propylene glycol methyl ether acetate;

[0058] The above components undergo free radical thermal polymerization at 80°C to obtain a 193nm photoresist resin solution;

[0059] Impurities and unreacted components in the 193nm photoresist resin solution obtained by thermal polymerization were removed using a precipitation-dissolution technique: a precipitant (n-heptane) was added to the solution containing the 193nm photoresist resin obtained by thermal polymerization, with the amount of precipitant added being three times that of the 193nm photoresist resin solution, and resin precipitate was precipitated under stirring conditions; the precipitated resin was separated from the liquid phase and vacuum dried to obtain solid resin; the solid resin was redissolved with a solvent (electronic grade cyclohexanone); the above steps were repeated four times to obtain a pure 193nm photoresist resin solution;

[0060] Metal impurities in the pure 193nm photoresist resin solution were removed by column filtration technology to obtain an ultrapure 193nm photoresist resin solution; the column packing material in the column filtration technology was polystyrene sulfonic acid resin.

Claims

1. A 193nm photoresist resin, characterized in that, It is produced by thermal polymerization of the following monomers in solvent in the presence of a free radical thermal initiator in parts by weight: 99.9–99.97 parts of etching-resistant methacrylate. 0.03–0.1 parts of urethane-containing methacrylates; wherein, The free radical thermal initiator is present in a mass fraction of 2 to 8 parts, and the solvent is present in a mass fraction of 100 to 300 parts.

2. The 193nm photoresist resin according to claim 1, characterized in that, The etching-resistant methacrylate is at least one of the following: 1-Methylcyclopentyl methacrylate, 1-ethylcyclopentyl methacrylate, 1-isopropylcyclopentyl methacrylate, 1-methylcyclohexyl methacrylate, 1-ethylcyclohexyl methacrylate, 1-isopropylcyclohexyl methacrylate, 2-methyl-2-adamantaneol methacrylate, 2-ethyl-2-adamantaneol methacrylate, 1-(1-adamantane)-1-methylethyl methacrylate, 2-isopropyl-2-adamantaneol methacrylate, 3-hydroxy-1-adamantaneol methacrylate, 2-carboxy-4-norbornolide-5-methacrylate, 2-carboxy-4-norbornolide-5-acetoxymethacrylate.

3. The 193nm photoresist resin according to claim 2, characterized in that, The etching-resistant methacrylate is one of 3 to 8 of the following: 1-Methylcyclopentyl methacrylate, 1-ethylcyclopentyl methacrylate, 1-isopropylcyclopentyl methacrylate, 1-methylcyclohexyl methacrylate, 1-ethylcyclohexyl methacrylate, 1-isopropylcyclohexyl methacrylate, 2-methyl-2-adamantaneol methacrylate, 2-ethyl-2-adamantaneol methacrylate, 1-(1-adamantane)-1-methylethyl methacrylate, 2-isopropyl-2-adamantaneol methacrylate, 3-hydroxy-1-adamantaneol methacrylate, 2-carboxy-4-norbornolide-5-methacrylate, 2-carboxy-4-norbornolide-5-acetoxymethacrylate.

4. The 193nm photoresist resin according to claim 1, characterized in that, The methacrylate containing carbamate is any one of the following: ethyl carbamate-2-methyl-2-adamantane methacrylate, ethyl carbamate-2-isopropyl-2-adamantane methacrylate, ethyl carbamate-2-ethyl-2-adamantane methacrylate.

5. The 193nm photoresist resin according to claim 1, characterized in that, The free radical thermal initiator is an azo thermal initiator or a peroxide thermal initiator; the azo thermal initiator includes azobisisobutyronitrile and dimethyl azobisisobutyrate; the peroxide thermal initiator is benzoyl peroxide.

6. The 193nm photoresist resin according to claim 1, characterized in that, The solvent is at least one of the following electronic-grade solvents: ethyl acetate, propylene glycol methyl ether acetate, and cyclohexanone.

7. A method for preparing the 193nm photoresist resin as described in claims 1-6, characterized in that, Includes the following steps: Weigh the above-mentioned parts by weight of the etching-resistant methacrylate, the urethane-containing methacrylate, the free radical thermal initiator, and the solvent. The above components undergo free radical thermal polymerization at 60-100°C to obtain the 193nm photoresist resin solution.

8. The method for preparing the 193nm photoresist resin according to claim 7, characterized in that, The following purification steps are also included: Impurities and unreacted components in the 193nm photoresist resin solution obtained by the thermal polymerization reaction are removed by precipitation-dissolution technology to obtain a pure 193nm photoresist resin solution. Metal impurities in the pure 193nm photoresist resin solution were removed by filtration to obtain an ultrapure 193nm photoresist resin solution.

9. The method for preparing the 193nm photoresist resin according to claim 8, characterized in that, The purification steps are specifically as follows: Impurities and unreacted components in the 193nm photoresist resin solution obtained by thermal polymerization are removed by precipitation-dissolution technology: a precipitant is added to the solution containing the 193nm photoresist resin obtained by thermal polymerization, the amount of the precipitant being 2 to 4 times that of the 193nm photoresist resin solution, and resin precipitate is precipitated under stirring conditions; the precipitated resin is separated from the liquid phase and vacuum dried to obtain solid resin; the solid resin is redissolved in a solvent; Repeat the above steps 3 to 5 times to obtain a pure 193nm photoresist resin solution; Metal impurities in the pure 193nm photoresist resin solution are removed by column filtration or membrane filtration to obtain an ultrapure 193nm photoresist resin solution; the column packing material in the column filtration technology is polystyrene sulfonic acid resin; the membrane filtration technology uses a commercial metal ion removal filter membrane.

10. The method for preparing the 193nm photoresist resin according to claim 9, characterized in that: The precipitant is at least one of the following electronic-grade precipitants: cyclohexane, n-hexane, n-heptane; the solvent is at least one of the following electronic-grade solvents: ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate, cyclohexanone.