Arf photoresist resin with stable PEB temperature response, and preparation method and application thereof

Abstract

The application belongs to the technical field of semiconductor materials, and relates to an ArF photoresist resin with stable PEB temperature response and a preparation method and application thereof. The ArF photoresist resin is prepared by copolymerization of acid-sensitive monomers, polar monomers and skeleton-regulating monomers; wherein the acid-sensitive monomers are 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, the polar monomers are hydroxyethyl methacrylate, and the skeleton-regulating monomers are cyclohexyl methacrylate. The ArF photoresist resin can be prepared into ArF photoresist together with a photoacid generator, a quencher and an organic solvent. The photoresist has a smaller threshold exposure dose change range under different PEB temperature conditions, and exhibits good PEB temperature response stability.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor materials technology, and relates to a photoresist resin, its preparation method and application. Background Technology

[0002] In advanced semiconductor manufacturing, photolithography is the core process for achieving high-precision transfer of micro- and nano-scale circuit patterns. Photoresist, as a key material, directly determines the accuracy, quality, and production efficiency of pattern transfer. With the continuous shrinking of device feature sizes, ArF (argon fluoride) 193 nm photolithography technology, with its high resolution and mature process system, remains widely used in advanced integrated circuit manufacturing. At the same time, manufacturing processes place higher demands on the transmittance, imaging stability, and process adaptability of ArF photoresist materials, especially on the material response stability during post-exposure heat treatment.

[0003] In ArF chemically amplified photoresist systems, the acids generated after exposure catalyze chemical transformations in the resin, such as deprotection, during subsequent heat treatment. This difference in solubility between the exposed and unexposed areas in the developer leads to pattern transfer. Therefore, post-exposure baking (PEB) is not only a crucial step in photolithography but also a key stage influencing the material's chemical response, development behavior, and the final image formation.

[0004] As 193 nm chemically amplified photoresist systems have matured, researchers have begun to more clearly consider PEB (Protective Bath) as a key reaction stage affecting imaging results. In 1999, Atsushi Sekiguchi et al. integrated the baking device into a Fourier transform infrared spectrometer to perform in-situ characterization of the decomposition of protecting groups in chemically amplified photoresists during the PEB process. They pointed out that during PEB, the acid diffusion generated by exposure and the removal reaction of protecting groups occur simultaneously, and the evolution of the protecting group concentration directly affects the dissolution behavior during the development process.

[0005] In 2003, Sangho Lee et al. conducted a systematic study on the behavior of ArF photoresist in the PEB process, focusing on the structure of photoacid generators (PAGs), processing conditions, and delay effects. This study primarily evaluated PEB sensitivity based on the change in CD caused by PEB temperature variations. The results showed that PAG anion size, PAG type, soft baking, and PEB conditions all significantly affect PEB sensitivity.

[0006] In subsequent research, Chi-Sun Hong et al. further expanded their research scope to the polymer and solvent levels in "PEB Sensitivity Studies of ArFResists (II): Polymer and Solvent Effects". This study showed that the content of acid-sensitive groups in the polymer, the deprotection activation energy, the solvent system, and baking conditions all significantly affect the sensitivity of PEB; among these, using acid-sensitive protecting groups with low activation energy and a lower proportion of acid-sensitive groups helps reduce response fluctuations caused by temperature changes.

[0007] The aforementioned studies provide an important foundation for understanding the temperature effects during the PEB process. However, their evaluation methods mainly focus on process characterization based on CD changes, reflecting more the response of the final image to temperature fluctuations. In contrast, the stability of resin deprotection and development behavior during PEB is the material basis determining the stability of the final image. Therefore, directly improving the chemical response and development behavior stability of materials under different PEB temperature conditions from the perspective of resin molecular structure design remains of significant research importance.

[0008] It is necessary to develop an ArF photoresist resin with stable PEB temperature response, so that it can maintain relatively stable exposure response and development behavior under different PEB temperature conditions. Summary of the Invention

[0009] To address the above problems, this invention provides a temperature-responsive ArF photoresist resin with PEB, its preparation method, and its application.

[0010] This invention is achieved through the following technical solution: On one hand, the present invention provides a PEB temperature-responsive ArF photoresist resin, wherein the ArF photoresist resin is obtained by copolymerization of an acid-sensitive monomer, a polar monomer and a framework-regulating monomer; the contents of the acid-sensitive monomer, the polar monomer and the framework-regulating monomer are 10-50%, 10-55% and 20-70% respectively by molar percentage.

[0011] The acid-sensitive monomer is one of 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, 1-ethyl-3-(trifluoromethyl)cyclopentyl methacrylate, 1-ethyl-3-(2,2-difluoroethyl)cyclopentyl methacrylate, and 1-ethyl-3-(fluoromethyl)cyclopentyl methacrylate, preferably 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate.

[0012] Furthermore, the polar monomer is one of hydroxyethyl methacrylate, glycidyl methacrylate, or tetrahydrofuran-2-methyl methacrylate, preferably hydroxyethyl methacrylate.

[0013] Furthermore, the skeleton regulating monomer is one of methyl methacrylate, isobutyl methacrylate, or cyclohexyl methacrylate, preferably cyclohexyl methacrylate.

[0014] Preferably, the contents of the acid-sensitive monomer, polar monomer, and skeleton-regulating monomer, respectively, are 25-45%, 10-40%, and 30-60% by molar percentage.

[0015] On the other hand, the present invention also provides a method for preparing the ArF photoresist resin, comprising the following steps: (1) Add the acid-sensitive monomer, polar monomer and framework-adjusting monomer to the reaction vessel, add tetrahydrofuran and mix well; (2) After heating to 64~68 °C under an inert atmosphere, azobisisobutyronitrile is added to the reaction system to carry out free radical polymerization to obtain the polymerization reaction solution; (3) The polymerization reaction solution is added to n-hexane to precipitate a solid product, which is then separated and vacuum dried to obtain the ArF photoresist resin.

[0016] Furthermore, the amount of the initiator azobisisobutyronitrile added is 0.5-5% of the total mass of the three monomers.

[0017] Furthermore, the tetrahydrofuran accounts for 60-80% of the total mass of the reaction system.

[0018] The present invention provides a photoresist comprising the above-mentioned ArF photoresist resin, a photoacid generator, a quencher, and an organic solvent.

[0019] Furthermore, the amount of the photoacid-generating agent added is 2-8% of the mass of the ArF photoresist resin.

[0020] Furthermore, the amount of the quenching agent added is 0.2-1% of the mass of the ArF photoresist resin.

[0021] Furthermore, the organic solvent accounts for 80-95% of the total mass of the photoresist.

[0022] This invention also provides the application of the above-mentioned ArF photoresist resin in ArF photoresist systems. Preferably, the ArF photoresist resin is a resin obtained by copolymerizing the acid-sensitive monomer 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, the polar monomer hydroxyethyl methacrylate, and the framework-regulating monomer cyclohexyl methacrylate, which is particularly suitable for photolithography processes that require high stability in the temperature response of PEB.

[0023] Compared with the prior art, the present invention has the following beneficial effects: In a preferred embodiment of the present invention, the ArF photoresist resin obtained by copolymerizing the acid-sensitive monomer 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, the polar monomer hydroxyethyl methacrylate, and the skeleton-regulating monomer cyclohexyl methacrylate, when used to formulate the photoresist, exhibits a small change in threshold exposure dose under different PEB temperature conditions; and under different photoacid-generating agent concentrations, it exhibits a small relative change range and a small absolute value of temperature response slope, indicating that the preferred resin system has good PEB temperature response stability. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0025] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means. Unless otherwise specified, the contents described in the examples and formulations below are by mass. Unless otherwise specified, the following operations are performed at room temperature.

[0026] Comparative Examples 1.1-1.3 The types and amounts of photoresist resin raw materials are shown in Table 1.

[0027] Table 1. Composition of resin raw materials in Comparative Examples 1.1-1.3

[0028] The preparation methods for Comparative Examples 1.1-1.3 are as follows: Cyclohexyl methacrylate, tert-butyl methacrylate, and hydroxyethyl methacrylate were weighed into a reaction vessel according to the amounts of raw materials shown in Table 1. Tetrahydrofuran was then added, and the mixture was stirred until all monomers were fully dissolved and homogeneous. Under nitrogen protection, the temperature was raised to 64-68 °C. Then, the amounts of azobisisobutyronitrile (AIBN) shown in Table 1 were dissolved in a certain amount of tetrahydrofuran and added to the reaction vessel, ensuring that tetrahydrofuran accounted for 60-80% of the total mass of the reaction system. The mixture was stirred continuously at 64-68 °C for 4-6 h. After the reaction was completed, the mixture was cooled to room temperature, and the resulting polymerization solution was slowly added to n-hexane to precipitate a solid product. After filtration and separation, the product was vacuum dried at 40-60 °C for 12-24 h to obtain the photoresist resin.

[0029] The number-average molecular weight (Mn) and dispersion index (PDI) of comparative examples 1.1-1.3 are shown in Table 2.

[0030] Table 2. Number-average molecular weight and dispersity index of the resins obtained in Comparative Examples 1.1-1.3

[0031]

Examples 1.1-1.3

[0032] Table 3. Composition of resin raw materials in Examples 1.1-1.3

[0033] The preparation methods of Examples 1.1-1.3 are as follows: Cyclohexyl methacrylate, 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, and hydroxyethyl methacrylate were weighed into a reaction vessel according to the raw material amounts shown in Table 3. Tetrahydrofuran was then added, and the mixture was stirred until all monomers were fully dissolved and homogeneous. Under nitrogen protection, the temperature was raised to 64-68°C. Then, azobisisobutyronitrile (ANOVA) of the amounts shown in Table 3 was dissolved in a certain amount of tetrahydrofuran and added to the reaction vessel, making the tetrahydrofuran account for 60-80% of the total mass of the reaction system. The mixture was stirred continuously at 64-68°C for 4-6 hours. After the reaction was completed, the mixture was cooled to room temperature, and the resulting polymerization solution was slowly added to n-hexane to precipitate a solid product. After filtration and separation, the product was vacuum dried at 40-60°C for 12-24 hours to obtain the photoresist resin.

[0034] The number-average molecular weight (Mn) and dispersion index (PDI) of Examples 1.1-1.3 are shown in Table 4.

[0035] Table 4. Number-average molecular weight and dispersity index of the resins obtained in Examples 1.1-1.3

[0036] Comparative Examples 2-4 The photoresist resins prepared in Comparative Example 1.3 were formulated into photoresists according to the formulations shown in Table 5.

[0037] Table 5. Photoresist formulation composition of Comparative Examples 2-4

[0038]

Examples 2-4

[0039] Table 6. Photoresist formulation composition in Examples 2-4

[0040] In Comparative Examples 2-4 and Examples 2-4, the organic solvent was propylene glycol methyl ether acetate, the photoacid generator was bis(4-tert-butylphenyl)iodonium perfluorobutane sulfonate, and the quencher was triethylamine.

[0041] According to the formulation amounts, the photoresists prepared in Comparative Examples 2-4 and Examples 2-4 were subjected to exposure characteristic tests at different PEB temperatures under the same coating, pre-baking, exposure, and development conditions. The specific methods are as follows: (1) Take the photoresist prepared in Comparative Examples 2-4 and Examples 2-4 and filter them with a filter membrane with a pore size of 0.22 μm respectively; (2) Pre-treat the 8-inch silicon wafer with hexamethyldisilazane (HMDS) to improve the adhesion of the photoresist film layer; then spin-coat the photoresist solution obtained in step (1) on the surface of the pre-treated silicon wafer and bake it at 105 ℃ / 60 s to obtain the photoresist film layer. (3) Expose the photoresist film layer using a deep ultraviolet light source with a wavelength of 193 nm; (4) After exposure, PEB is applied at 100~120 ℃ / 60 s on a hot plate. The exposed photoresist film is then developed at 23 ℃ / 60 s using an alkaline developer (2.38wt% tetramethylammonium hydroxide aqueous solution, TMAH). The film thickness changes before and after development are recorded.

[0042] Based on Comparative Example 2 and Example 2, the results of the development threshold exposure dose E at different PEB temperatures are shown in Table 7.

[0043] Table 7. Threshold exposure dose and relative change rate of Comparative Example 2 and Example 2 at different PEB temperatures.

[0044] As shown in Table 7, at lower photoacid-generating agent concentrations, the threshold exposure dose variation of Example 2 of the present invention is small at different PEB temperatures, indicating that it has good PEB temperature response stability under low photoacid-generating agent concentration conditions.

[0045] Based on Comparative Example 3 and Example 3, the results of the development threshold exposure dose E at different PEB temperatures are shown in Table 8.

[0046] Table 8 Threshold exposure doses and relative change rates of Comparative Example 3 and Example 3 at different PEB temperatures.

[0047] Based on Comparative Example 4 and Example 4, the results of the development threshold exposure dose E at different PEB temperatures are shown in Table 9.

[0048] Table 9 Threshold exposure doses and relative change rates at different PEB temperatures for Comparative Example 4 and Example 4

[0049] As shown in Tables 8 and 9, under moderate and high concentrations of photoacid generators, the threshold exposure doses of Examples 3 and 4 of the present invention are generally low at various PEB temperatures, and their drift with temperature is small, indicating that the resin of the present invention can maintain a relatively stable exposure response under different concentrations of photoacid generators.

[0050] To further compare the overall response of different samples to PEB temperature changes, the maximum range of threshold exposure dose variation, relative range of variation, and absolute value of temperature response slope under each condition are summarized in Table 10. The maximum range of variation is the difference between the maximum and minimum values ​​of the threshold exposure dose at each temperature point; the relative range of variation is the ratio of the maximum range of variation to the threshold exposure dose at 110 ℃; the absolute value of the temperature response slope is the absolute value of the slope obtained after linearly fitting the threshold exposure dose to the PEB temperature, used to characterize the overall trend of threshold exposure dose variation with PEB temperature. The smaller the absolute value, the less sensitive the sample is to PEB temperature changes.

[0051] Table 10. Stability evaluation results of different sample threshold exposure doses as a function of PEB temperature.

[0052] Furthermore, as shown in Table 10, compared with Comparative Examples 2-4, Examples 2-4 of the present invention exhibit a smaller relative variation range and a smaller absolute value of the temperature response slope under different photoacid-generating agent concentrations, indicating that the resin of the present invention has a smaller threshold exposure dose fluctuation caused by changes in PEB temperature and has better PEB temperature response stability.

[0053] In summary, the resin of the present invention can maintain a relatively stable exposure response under different PEB temperature conditions, and the above trend still holds true under different concentrations of photoacid generator, indicating that the resin of the present invention has good PEB temperature response stability and certain formulation adaptability.

Claims

1. A temperature-responsive ArF photoresist resin, characterized in that, The ArF photoresist resin is prepared by copolymerization of acid-sensitive monomer 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, polar monomer hydroxyethyl methacrylate, and skeleton-regulating monomer cyclohexyl methacrylate.

2. The temperature-responsive ArF photoresist resin according to claim 1, characterized in that, Based on molar percentage, the contents of the acid-sensitive monomer 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, the polar monomer hydroxyethyl methacrylate, and the skeleton-regulating monomer cyclohexyl methacrylate are 10-50%, 10-55%, and 20-70%, respectively.

3. The temperature-responsive ArF photoresist resin according to claim 2, characterized in that, Based on molar percentage, the contents of the acid-sensitive monomer 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, the polar monomer hydroxyethyl methacrylate, and the skeleton-regulating monomer cyclohexyl methacrylate are 25-45%, 10-40%, and 30-60%, respectively.

4. A method for preparing the PEB temperature-responsive ArF photoresist resin according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Add the acid-sensitive monomer 1-ethyl-3-(2,2,2-trifluoroethyl)cyclopentyl methacrylate, the polar monomer hydroxyethyl methacrylate, and the skeleton-regulating monomer cyclohexyl methacrylate to the reaction vessel, add tetrahydrofuran and mix well; (2) After heating to 64~68 °C under an inert atmosphere, azobisisobutyronitrile is added to the reaction system to carry out free radical polymerization to obtain the polymerization reaction solution; (3) The polymerization reaction solution is added to n-hexane to precipitate solid products, which are then separated and vacuum dried to obtain the PEB temperature-responsive ArF photoresist resin.

5. The preparation method according to claim 4, characterized in that, The amount of azobisisobutyronitrile added is 0.5-5% of the total mass of the three monomers.

6. The preparation method according to claim 4, characterized in that, The tetrahydrofuran accounts for 60-80% of the total mass of the reaction system.

7. An ArF photoresist, characterized in that, It includes the PEB temperature-responsive ArF photoresist resin, photoacid generator, quencher, and organic solvent as described in any one of claims 1 to 3.

8. The ArF photoresist according to claim 7, characterized in that, The amount of the photoacid generator added is 2-8% of the mass of the PEB temperature-responsive ArF photoresist resin; the amount of the quencher added is 0.2-1% of the mass of the PEB temperature-responsive ArF photoresist resin; and the organic solvent accounts for 80-95% of the total mass of the ArF photoresist.

9. The application of the PEB temperature-responsive ArF photoresist resin according to any one of claims 1 to 3 in the preparation of ArF photoresist or in the ArF photolithography process.

Images