Low-toxicity solvent system photoresist formula and application thereof in green manufacturing

Abstract

The invention relates to the technical field of photoresist preparation, and particularly discloses a low-toxicity solvent system photoresist formula and application of the low-toxicity solvent system photoresist formula in green manufacturing. Polyacrylic acid is grafted to hydroxyethyl cellulose through esterification reaction to obtain modified hydroxyethyl cellulose, and the modified hydroxyethyl cellulose is subjected to modification treatment to obtain the low-toxicity solvent system photoresist. The solubility of hydroxyethyl cellulose in a blended solvent of ethyl lactate and gamma-valerolactone is improved, the surface tension of the photoresist can be adjusted by the modified hydroxyethyl cellulose, and the leveling property of the photoresist is remarkably improved; meanwhile, the modified hydroxyethyl cellulose can also be used as a thickening agent, has good thickening capacity, can adjust the viscosity of the photoresist solution, ensures that the photoresist solution uniformly covers the surface of a substrate in the spin coating process to form a film with consistent thickness, and can avoid the problem of non-uniform coating thickness caused by too low viscosity.

Description

Technical Field

[0001] The present invention relates to the technical field of photoresist preparation, and particularly relates to a low-toxicity solvent system photoresist formulation and its application in green manufacturing. Background Art

[0002] Semiconductor manufacturing is a highly complex and precise process flow, covering multiple key processes such as cleaning, coating, lithography, etching, etc. Among them, the lithography process is the core link of the entire semiconductor manufacturing, and photoresist coating is the starting step of this key process, and its quality directly determines the success or failure of subsequent processes. Common photoresist coating methods include spin coating, slit coating, spraying, roller coating, etc. However, no matter which coating method is used, due to the existence of the surface tension of the photoresist, the coated liquid film has a tendency to overflow and diffuse outward, resulting in the phenomenon of photoresist accumulation at the edge of the substrate. The film thickness of this edge photoresist is relatively thick, and it is easy to cause the problem of photoresist residue during development, which in turn affects the pattern accuracy and performance of the chip. Therefore, selecting a suitable photoresist solvent to optimize the coating effect and reduce edge accumulation is of crucial significance for improving lithography quality and production efficiency.

[0003] However, the solvents widely used in traditional photoresist formulations have problems such as high toxicity and serious environmental pollution. These solvents will release harmful gases during use, which not only pose a threat to the health of operators but also cause irreversible damage to the environment. With the increasing global attention to environmental protection, the semiconductor industry is also facing huge pressure for green development.

[0004] Therefore, the development and application of environmentally friendly photoresist solvents and the reduction of the use of traditional solvents have become the key bottlenecks for the semiconductor industry to achieve sustainable development. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a low-toxicity solvent system photoresist formulation and its application in green manufacturing.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: A low-toxicity solvent system photoresist formulation, comprising phenolic resin, photoacid generator, quencher, leveling agent and photoresist solvent. The photoresist solvent is composed of ethyl lactate and γ-valerolactone, and the leveling agent is modified hydroxyethyl cellulose.

[0007] In the technical solution disclosed by the present invention, in the photoresist solvent, the mass ratio of ethyl lactate to γ-valerolactone is 7-8:1-2. For example, 7:1, 7:1.5, 7:2, 7.5:1.5, 8:1, 8:1.5, 8:2 can be selected, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0008] In the technical solution disclosed by the present invention, the preparation method of the modified hydroxyethyl cellulose is as follows: Under nitrogen protection, hydroxyethyl cellulose and polyacrylic acid are added to dimethyl sulfoxide, stirred and dispersed evenly, then dicyclohexylcarbodiimide and 4-dimethylaminopyridine are added, and heated and stirred under reflux. After the reaction is completed, it is cooled to room temperature, filtered, washed, and freeze-dried to obtain the modified hydroxyethyl cellulose.

[0009] In the technical solution disclosed by the present invention, the hydroxyl group in hydroxyethyl cellulose and the carboxyl group in polyacrylic acid undergo an esterification reaction to obtain the modified hydroxyethyl cellulose, where dicyclohexylcarbodiimide serves as a dehydrating agent and 4-dimethylaminopyridine serves as a catalyst.

[0010] Specifically, the mass ratio of hydroxyethyl cellulose, polyacrylic acid, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 3.5-5:1.5-2.5:1-2:1-1.5.

[0011] Specifically, the temperature of the heating and stirring under reflux reaction is 40-60°C, for example, 40°C, 45°C, 50°C, 55°C, 60°C can be selected; the time of the heating and stirring under reflux reaction is 2-4h, for example, 2h, 2.5h, 3h, 3.5h, 4h can be selected, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0012] In the technical solution disclosed by the present invention, based on the total mass of the photoresist formulation, the content of phenolic resin is 10-25wt%, the content of photoacid generator is 5-10wt%, the content of quencher is 0.5-1wt%, the content of leveling agent is 1-2wt%, and the rest is the photoresist solvent.

[0013] In the technical solution disclosed by the present invention, the photoacid generator is selected from diazonium salts, sulfonium salts or iodonium salts, for example, diphenyliodonium perfluoro-1-butanesulfonate, triphenylsulfonium chloride, 1-(2-naphthoylmethyl)thiolonium trifluoromethanesulfonate, bis(cyclohexylsulfonyl)diazomethane can be selected.

[0014] In the technical solution disclosed by the present invention, the quencher is selected from ethanolamine, diethanolamine, triethanolamine or trihexylamine.

[0015] The present invention also provides the application of the above low-toxic solvent system photoresist formulation in green manufacturing.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The commonly used photoresist solvent PGMEA (propylene glycol methyl ether acetate) is highly toxic at present. While the alternative solvent ethyl lactate is environmentally friendly, its surface tension reaches 33.2 mN / m. Due to the excessive surface tension of ethyl lactate, the coating thickness is uneven. In the present invention, by compounding ethyl lactate and γ-valerolactone, the problem of uneven coating thickness caused by the excessive surface tension of ethyl lactate can be effectively solved.

[0017] (2) In the present invention, polyacrylic acid is grafted onto hydroxyethyl cellulose through an esterification reaction to obtain modified hydroxyethyl cellulose. By modifying hydroxyethyl cellulose, the solubility of hydroxyethyl cellulose in the blend solvent of ethyl lactate and γ-valerolactone is improved. The modified hydroxyethyl cellulose can adjust the surface tension of the photoresist and significantly improve the leveling property of the photoresist. At the same time, the modified hydroxyethyl cellulose can also be used as a thickener, which has good thickening ability and can adjust the viscosity of the photoresist solution to ensure that it uniformly covers the surface of the substrate during the spin-coating process and forms a film with a uniform thickness, thus avoiding the problem of uneven coating thickness caused by too low viscosity. Description of the Drawings

[0018] Figure 1 It is a test result diagram of the film thickness uniformity of different groups of photoresists. Detailed Embodiments

[0019] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0020] It should be noted that unless otherwise specified, the chemical reagents involved in the present invention are purchased through commercial channels.

[0021] The phenolic resin used in the present invention is a linear phenolic resin, purchased from Jiangsu Guster New Materials Co., Ltd.; the CAS number of polyacrylic acid: 9003-01-4, and the average relative molecular mass: 250,000. Example 1

[0022] A low-toxicity solvent system photoresist formulation. Based on the total mass of the photoresist formulation, the content of phenolic resin is 10 wt%, the content of photoacid generator triphenylsulfonium chloride is 5 wt%, the content of quencher ethanolamine is 0.5 wt%, the content of leveling agent is 1 wt%, and the rest is the photoresist solvent. The photoresist solvent is composed of ethyl lactate and γ-valerolactone, and the mass ratio of ethyl lactate to γ-valerolactone is 7:1; The leveling agent is modified hydroxyethyl cellulose, and its preparation method is as follows: Under nitrogen protection, 3.5 g of hydroxyethyl cellulose and 1.5 g of polyacrylic acid were added to 150 mL of dimethyl sulfoxide, stirred and dispersed evenly, then 1 g of dicyclohexylcarbodiimide and 1 g of 4-dimethylaminopyridine were added, and the mixture was heated and stirred under reflux at 60 °C for 2 h. After the reaction was completed, the temperature was lowered to room temperature, and then filtered, washed, and freeze-dried to obtain modified hydroxyethyl cellulose. Example 2

[0023] A low-toxicity solvent system photoresist formulation. Based on the total mass of the photoresist formulation, the content of phenolic resin is 25 wt%, the content of photoacid generator bis(cyclohexylsulfonyl) diazomethane is 10 wt%, the content of quencher triethanolamine is 1 wt%, the content of leveling agent is 2 wt%, and the rest is the photoresist solvent. The photoresist solvent is composed of ethyl lactate and γ-valerolactone, and the mass ratio of ethyl lactate to γ-valerolactone is 8:2. The leveling agent is modified hydroxyethyl cellulose, and its preparation method is as follows: Under nitrogen protection, 5 g of hydroxyethyl cellulose and 2.5 g of polyacrylic acid were added to 150 mL of dimethyl sulfoxide, stirred and dispersed evenly, then 2 g of dicyclohexylcarbodiimide and 1.5 g of 4-dimethylaminopyridine were added, and the mixture was heated and stirred under reflux at 60 °C for 2 h. After the reaction was completed, the temperature was lowered to room temperature, and then filtered, washed, and freeze-dried to obtain modified hydroxyethyl cellulose. Example 3

[0024] A low-toxicity solvent system photoresist formulation. Based on the total mass of the photoresist formulation, the content of phenolic resin is 20 wt%, the content of photoacid generator triphenylsulfonium chloride is 8 wt%, the content of quencher triethanolamine is 0.8 wt%, the content of leveling agent is 1.5 wt%, and the rest is the photoresist solvent. The photoresist solvent is composed of ethyl lactate and γ-valerolactone, and the mass ratio of ethyl lactate to γ-valerolactone is 7:2. The leveling agent is modified hydroxyethyl cellulose, and its preparation method is as follows: Under nitrogen protection, 5 g of hydroxyethyl cellulose and 2.5 g of polyacrylic acid were added to 150 mL of dimethyl sulfoxide, stirred and dispersed evenly, then 2 g of dicyclohexylcarbodiimide and 1.5 g of 4-dimethylaminopyridine were added, and the mixture was heated and stirred under reflux at 60 °C for 2 h. After the reaction was completed, the temperature was lowered to room temperature, and then filtered, washed, and freeze-dried to obtain modified hydroxyethyl cellulose. Example 4

[0025] A low-toxicity solvent system photoresist formulation. Based on the total mass of the photoresist formulation, the content of phenolic resin is 15 wt%, the content of photoacid generator bis(cyclohexylsulfonyl)diazomethane is 6 wt%, the content of quencher ethanolamine is 0.6 wt%, the content of leveling agent is 1.5 wt%, and the rest is the photoresist solvent. The photoresist solvent consists of ethyl lactate and γ-valerolactone, and the mass ratio of ethyl lactate to γ-valerolactone is 8:1; The leveling agent is modified hydroxyethyl cellulose, and its preparation method is as follows: Under nitrogen protection, 4 g of hydroxyethyl cellulose and 2 g of polyacrylic acid are added to 150 mL of dimethyl sulfoxide, stirred and dispersed evenly, then 1.5 g of dicyclohexylcarbodiimide and 1.2 g of 4-dimethylaminopyridine are added, and the mixture is heated and stirred under reflux at 60 °C for 2 h. After the reaction is completed, it is cooled to room temperature, filtered, washed, and freeze-dried to obtain modified hydroxyethyl cellulose. Comparative Example 1

[0026] A low-toxicity solvent system photoresist formulation. Based on the total mass of the photoresist formulation, the content of phenolic resin is 10 wt%, the content of photoacid generator triphenylsulfonium chloride is 5 wt%, the content of quencher ethanolamine is 0.5 wt%, and the rest is the photoresist solvent. The photoresist solvent consists of ethyl lactate and γ-valerolactone, and the mass ratio of ethyl lactate to γ-valerolactone is 7:1.

[0027] Compared with Example 1, Comparative Example 1 does not add a leveling agent. Comparative Example 2

[0028] A low-toxicity solvent system photoresist formulation. Based on the total mass of the photoresist formulation, the content of phenolic resin is 10 wt%, the content of photoacid generator triphenylsulfonium chloride is 5 wt%, the content of quencher ethanolamine is 0.5 wt%, the content of leveling agent polyacrylic acid is 1 wt%, and the rest is the photoresist solvent. The photoresist solvent consists of ethyl lactate and γ-valerolactone, and the mass ratio of ethyl lactate to γ-valerolactone is 7:1.

[0029] Compared with Example 1, Comparative Example 2 uses polyacrylic acid to replace modified hydroxyethyl cellulose. Comparative Example 3

[0030] A low-toxicity solvent system photoresist formulation. Based on the total mass of the photoresist formulation, the content of phenolic resin is 10 wt%, the content of photoacid generator triphenylsulfonium chloride is 5 wt%, the content of quencher ethanolamine is 0.5 wt%, the content of leveling agent is 1 wt%, and the rest is the photoresist solvent. The photoresist solvent is ethyl lactate; The leveling agent is modified hydroxyethyl cellulose, and its preparation method is as follows: Under nitrogen protection, 3.5 g of hydroxyethyl cellulose and 1.5 g of polyacrylic acid were added to 150 mL of dimethyl sulfoxide, stirred and dispersed evenly, then 1 g of dicyclohexylcarbodiimide and 1 g of 4-dimethylaminopyridine were added, and the mixture was heated and stirred under reflux at 60 °C for 2 h. After the reaction was completed, the temperature was lowered to room temperature, and the product was obtained by suction filtration, washing, and freeze-drying, namely modified hydroxyethyl cellulose.

[0031] Compared with Example 1, ethyl lactate was selected as the photoresist solvent in Comparative Example 3.

[0032] Photoresist solutions were prepared according to the formulations in Examples 1-4 and Comparative Examples 1-3 respectively. The specific steps were as follows: Phenolic resin, photoacid generator, quencher, and leveling agent were added to the photoresist solvent, and the mixture was shaken in the dark to dissolve completely, and then filtered through a 0.22-micron filter to obtain the photoresist solution.

[0033] The photoresist solutions prepared in Examples 1-4 and Comparative Examples 1-3 were spin-coated on silicon wafers treated with hexamethyldisilazane (HMDS), and baked at 90 °C for 120 s to obtain a photoresist layer with a thickness of 200 nm. Exposure was carried out using a 193 nm (ArF) lithography machine, and the exposure dose was 40 mJ / cm 2 , after exposure, baking was carried out on a hot stage at 90 °C for 60 s, and development was carried out using an alkaline aqueous developer (2.38 wt% aqueous solution of tetramethylammonium hydroxide). The development time was 60 s. The photoresist was made into a circuit, and then the uniformity of the photoresist film thickness in the middle area was tested using a Kosaka ET150 micro-shape measuring machine. The evaluation method was to randomly select 5 points in the middle area to measure the photoresist film thickness. Film thickness uniformity = (maximum value - minimum value) / (maximum value + minimum value) × 100%. The test results are as Figure 1 shown. It can be seen from Figure 1 that in Comparative Example 1, no leveling agent was added, and in Comparative Example 2, polyacrylic acid was used to replace the modified hydroxyethyl cellulose in this application. The film thickness uniformity of the photoresist samples prepared in Comparative Example 1 and Comparative Example 2 was inferior to that of the examples of the present invention, indicating that adding modified hydroxyethyl cellulose can improve the leveling effect of the photoresist. In Comparative Example 3, γ-valerolactone was not added to the solvent. Compared with Example 1, it can be seen that adding a certain amount of γ-valerolactone can improve the leveling effect of the photoresist and the uniformity of the photoresist film thickness.

[0034] Finally, it should be noted that the above examples do not limit the present invention in any form. For those skilled in the art, based on the present invention, some modifications and improvements can be made. Therefore, any modification or improvement made without departing from the spirit of the present invention falls within the scope of protection required by the present invention.

Claims

1. A low-toxic solvent system photoresist formulation, comprising a phenolic resin, a photoacid generator, a quencher, a leveling agent and a photoresist solvent, characterized in that: The photoresist solvent consists of ethyl lactate and gamma-valerolactone, and the leveling agent is modified hydroxyethyl cellulose.

2. The low toxicity solvent system photoresist formulation according to claim 1, characterized in that: In the photoresist solvent, the mass ratio of ethyl lactate to γ-valerolactone is 7-8:1-2.

3. The low toxicity solvent system photoresist formulation according to claim 1, characterized in that: The preparation method of the modified hydroxyethyl cellulose is as follows: Under nitrogen protection, hydroxyethyl cellulose and polyacrylic acid are added to dimethyl sulfoxide, stirred and dispersed evenly, and then dicyclohexylcarbodiimide and 4-dimethylaminopyridine are added, heated and stirred under reflux for reaction, and after the reaction is completed, the mixture is cooled to room temperature, filtered, washed, and freeze-dried to obtain modified hydroxyethyl cellulose.

4. The low toxicity solvent system photoresist formulation according to claim 3, characterized in that: The mass ratio of hydroxyethyl cellulose, polyacrylic acid, dicyclohexylcarbodiimide and 4-dimethylaminopyridine is 3.5-5:1.5-2.5:1-2:1-1.

5.

5. The low toxicity solvent system photoresist formulation according to claim 3, characterized in that: The temperature of the heating, stirring and reflux reaction is 40-60° C., and the time of the heating, stirring and reflux reaction is 2-4 h.

6. The low-toxicity solvent system photoresist formulation according to claim 1, characterized in that: Based on the total weight of the photoresist formulation, the content of phenolic resin is 10-25wt%, the content of photoacid generator is 5-10wt%, the content of quencher is 0.5-1wt%, the content of leveling agent is 1-2wt%, and the rest is photoresist solvent.

7. The low-toxicity solvent system photoresist formulation according to claim 1, characterized in that: The photoacid generator is selected from diazonium salts, sulfonium salts or iodonium salts.

8. The low-toxicity solvent system photoresist formulation according to claim 1, characterized in that: The quencher is selected from ethanolamine, diethanolamine, triethanolamine or trihexylamine.

9. Use of the low-toxicity solvent system photoresist formulation according to any one of claims 1 to 8 in green manufacturing.

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