PAG bonding type photoresist film-forming resin and preparation method thereof

Abstract

The invention discloses PAG (Polyacrylamide) bonded photoresist film-forming resin which is prepared from four monomers, namely tetrahydrofurfuryl methacrylate, 2-isopropyl-2-adamantyl methacrylate, methacrylic acid and 4-(vinyl) benzenesulfonic acid triphenylsulfonium salt through a reversible addition-fragmentation chain transfer polymerization method, and the structural formula of the PAG bonded photoresist film-forming resin is as shown in formula 1. According to the invention, the PAG unit is doped into the photoresist resin polymer skeleton, the generated photoacid is not randomly dispersed any more, and the diffusion of the photoacid is limited within a certain distance. When the photoresist film-forming resin is applied to photoresist, the phenomena of acid diffusion, phase separation and the like and the line width roughness can be reduced, and the resolution ratio and the imaging effect of the photoresist are improved. The RAFT method is applied to preparation of the PAG bonded resin, and the application field of the RAFT method for preparing the polymer with controllable molecular weight and distribution is widened. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of photolithography in micro-fabrication, and in particular relates to a photoresist in the technical field of photolithography, a preparation method thereof and an application in photolithography. Background Art

[0002] With the continuous development of Moore's Law, integrated circuits have placed increasingly higher demands on photolithography processes. Photoresist is the most core consumable in the photolithography process, and its performance determines the quality of photolithography. As an "intermediary" for image transfer, photoresist plays a transfer role through the exposure, development and etching process. Through exposure, a solubility difference is formed between the mask area and the exposure area, thereby transferring the pattern on the mask to the substrate. The solubility of the exposure area increases to form a positive photoresist, and the solubility of the exposure area decreases to form a negative photoresist. After more than half a century of development, photoresist has evolved from ultraviolet to deep ultraviolet to extreme ultraviolet, and resolution requirements have continued to increase.

[0003] Since its introduction in 1982, chemically amplified resists (CARs) have become the main choice for chip manufacturing due to their high sensitivity and high resolution. CARs mainly contain film-forming resins and photoacid generators (PAGs). PAGs can be photolyzed to produce proton acids under exposure conditions. Proton acids catalyze the detachment of acid-labile groups on the film-forming resins, thereby forming solubility changes before and after exposure, and realizing pattern transfer. However, most PAGs are ionic, which leads to inherent incompatibility between PAGs and polymer resins in traditional PAG blend systems, resulting in problems such as phase separation, uneven PAG distribution caused by diffusion during pre-baking, and acid migration during post-exposure baking (PEB). In order to overcome these problems, polymer-bound PAGs have been widely studied. The incorporation of PAG functional groups into the polymer backbone is conducive to obtaining more uniform PAG distribution and greater PAG loading, avoiding phase separation of high-content PAGs and photoresist films. In addition, when PAG is incorporated into the polymer chain, the generated photoacid is no longer randomly dispersed, and its diffusion is limited to a certain distance, which is beneficial to improve the resolution and reduce the edge roughness. Therefore, polymer-incorporated PAG is regarded as one of the most important solutions for preparing high-performance deep ultraviolet and EUV photoresists.

[0004] Traditional free radical polymerization has problems such as wide molecular weight distribution, difficult to control molecular weight, and easy composition drift. Especially compared with other monomers, PAG containing double bonds shows obvious reactivity differences, which is more likely to cause uneven composition between polymer chains. Reversible addition fragmentation chain transfer (RAFT) free radical polymerization can effectively inhibit double radical termination and disproportionation termination in free radical polymerization, maintain the reactivity of monomers throughout the polymerization process, and can better control the relative molecular weight and its distribution, and prepare polymers with different structures, low PDI values ​​and controllable molecular weight.

[0005] The prior art mostly focuses on the preparation of PAG containing double bonds and the preparation of film-forming resins by traditional free radical polymerization or RAFT method and then blending with PAG to form a photoresist. For example, CN112592304A discloses a polymerizable photoacid generator containing a di-onium salt structure, and is used for the preparation of photoresist film-forming resins by traditional free radical polymerization; CN105348432B discloses a method for preparing a polymer-type sulfonium salt photoacid generator, and prepares a film-forming resin by traditional free radical polymerization; CN105237669A discloses a method for preparing a 248nm deep ultraviolet photoresist film-forming resin based on RAFT polymerization, and the obtained copolymer has a narrow molecular weight distribution, and then blended with PAG to form a photoresist solution. Summary of the invention

[0006] The purpose of the present invention is to provide a PAG-bonded photoresist film-forming resin prepared by RAFT polymerization in view of the above-mentioned problems of the prior art, which can improve the problems of photolithography roughness and poor imaging effect caused by acid diffusion and phase separation of PAG.

[0007] The present invention is achieved through the following technical solutions.

[0008] The present invention first provides a PAG bonded photoresist film-forming resin, which is a copolymer formed by polymerizing a plurality of polymerizable monomers, wherein the polymerizable monomers at least include tetrahydrofurfuryl methacrylate (THFMA), 2-isopropyl-2-adamantyl methacrylate (IAdMA), methacrylic acid (MAA) and 4-(vinyl)benzenesulfonium triphenylsulfonium salt (VBS-TPS).

[0009] More specifically, the general structural formula of the PAG-bonded photoresist film-forming resin provided by the present invention is as follows:

[0010]

[0011] Among them, x:y:z:n=30-45:40-60:5-15:3-15.

[0012] The PAG bonded photoresist film-forming resin of the present invention is selected by the inventors from tetrahydrofurfuryl methacrylate, 2-isopropyl-2-adamantyl methacrylate, methacrylic acid, and 4-(vinyl)benzenesulfonium triphenylsulfonium salt as polymerization monomers, which is a preferred combination explored through various theories and experiments. When used as a photoresist resin, the methacrylate photoresist has good light transmittance at 193nm, and the polar groups contained in tetrahydrofurfuryl methacrylate can increase the adhesion of the polymer to the silicon wafer; the adamantane C / H contained in 2-isopropyl-2-methacrylate adamantyl ester is relatively high, which can increase the etching resistance of the photoresist; and methacrylic acid controls the solubility and water development dynamics; 4-(vinyl)benzenesulfonic acid triphenylsulfonium salt is used as a polymerizable PAG to provide photoacid after exposure; during the exploration process, the inventors found that the polymer formed by the polymerization of these four polymerized monomers at a molar fraction ratio of 30-45:40-60:5-15:3-15, when used as a photoresist, the balance of the interaction of each monomer at this ratio makes the obtained polymer have the best effect in controlling the size and distribution of the molecular weight, reducing the acid diffusion phenomenon and line width roughness, and improving the resolution and imaging effect of the photoresist.

[0013] The present invention also provides a method for preparing the above-mentioned PAG-bonded photoresist film-forming resin, which is prepared by polymerization using a reversible addition-fragmentation chain transfer (RAFT) polymerization method and comprises the following steps.

[0014] (1) Tetrahydrofurfuryl methacrylate, methacrylic acid, 2-isopropyl-2-methacrylate adamantyl ester, 4-(vinyl)benzenesulfonic acid triphenylsulfonium salt, RAFT agent and first solvent are added to a brown flask, nitrogen is passed for 20 to 40 minutes, the temperature is raised to the first temperature zone, the initiator is injected, and the temperature is raised to the second temperature zone after the reaction for 1 to 1.5 hours. The first temperature zone is in the temperature range of 60 to 70° C., and the second temperature zone is in the temperature range of 65 to 75° C.

[0015] (2) Under sealed conditions, the reaction temperature is maintained in the second temperature zone and the reaction is continued for 19 to 22.5 hours. After the reaction is completed, the solid is precipitated with water, washed with n-hexane, and then dried in an oven at a temperature of 60 to 80° C. to obtain the PAG bonded photoresist film-forming resin.

[0016] The RAFT agent is selected from any one of 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 4-cyano-4-(phenylcarbonylthio)pentanoic acid, 2-(dodecylthiocarbonylthiothiothio)propionic acid, 2-phenyl-2-propylbenzodisulfide, 2-cyano-2-propylbenzodisulfide, 2-cyano-2-propyldodecyl trithiocarbonate, 2-cyano-2-propyldodecyl trithiocarbonate, and 1-(methoxycarbonyl)ethylbenzene dithioate.

[0017] The first solvent is selected from one or more of N,N-dimethylformamide (DMF), propylene glycol methyl ether acetate, 1,4-dioxane, and N-methylpyrrolidone.

[0018] The initiator is an azo free radical initiator or a peroxide free radical initiator, wherein the azo free radical initiator is selected from any one of azobisisobutyronitrile (AIBN), azobisisoheptanenitrile, dimethyl azobisisobutyrate, etc.; and the peroxide free radical initiator is selected from any one of dibenzoyl peroxide, tert-butyl hydroperoxide, benzoic acid hydroperoxide, etc.

[0019] Furthermore, in the above step 1, the solid content of the reaction system formed after the reactants are added is 20-40%.

[0020] Furthermore, the molar ratio of each component in the reaction system formed after the reactants are added in the above step 1 satisfies: monomer: RAFT agent: initiator is 250-350: 0.5-1.5: 0.2-0.5; the molar ratio of the monomers added is 30-45: 40-60: 5-15: 3-15.

[0021] The present invention also provides a photoresist composition, which is formed by mixing the above-mentioned PAG bonded photoresist film-forming resin and a solvent, wherein the mass fraction of the resin is 5%-30%. The solvent is selected from any one or more of propylene glycol methyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, ethyl acetate, ethylene glycol monomethyl ether acetate, tetrahydrofuran, acetone, cyclohexanone, N,N-dimethylformamide or methanol.

[0022] The present invention also provides a method for forming a photolithography pattern, using the above-mentioned photoresist composition, coating the photoresist composition on a substrate to be photolithographically processed, such as a silicon wafer, performing pre-baking, covering a mask on the photoresist composition, exposing, post-baking and developing, and cleaning with deionized water to obtain the photolithography pattern.

[0023] More specifically, the method for forming the photolithographic pattern is as follows: spin-coating the above-mentioned photoresist composition on the substrate to be photolithographically coated, pre-baking at 110°C for 90s, covering the baked photoresist composition with a mask, and exposing the photoresist composition to light at an exposure rate of 105 mJ / cm 2 After the exposure is completed, the film is post-baked at 100°C for 30 seconds, and then developed in a 2.38% tetramethylammonium hydroxide developer, and then the developer is washed away with deionized water to obtain a photolithography pattern.

[0024] The beneficial effects of the present invention are that a PAG-bonded photoresist film-forming resin is prepared by a RAFT active free radical polymerization method, and the method can better control the size and distribution of the molecular weight, which is beneficial to improving the resolution and reducing the edge roughness; and when PAG is incorporated into the polymer chain, the generated photoacid is no longer randomly dispersed, and its diffusion is limited within a certain distance. These enable the obtained photoresist film-forming resin to reduce acid diffusion and phase separation phenomena and line width roughness when applied to photoresist, and improve the resolution and imaging effect of the photoresist. The present invention applies the RAFT method to the preparation of PAG-bonded resins, broadening the application field of the RAFT method for preparing polymers with controllable molecular weight and distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The following is a synthetic route of the PAG-bonded photoresist film-forming resin in each embodiment of the present invention.

[0026] Figure 2 This is the infrared spectrum of the copolymer synthesized in Example 1 of the present invention.

[0027] Figure 3 This is the NMR spectrum of the copolymer synthesized in Example 1 of the present invention.

[0028] Figure 4 This is a graph showing the thermal properties test results of the copolymer synthesized in Example 1 of the present invention.

[0029] Figure 5 The sensitivity curve of the photoresist composition formed by using the copolymer synthesized in Examples 1-4 of the present invention as a photoresist film-forming resin.

[0030] Figure 6 The acid diffusion length curve of the photoresist composition formed by using the copolymer prepared in Example 1 of the present invention as a photoresist film-forming resin.

[0031] Figure 7 The AFM and SEM images of the photolithographic pattern obtained after photolithography and development using the copolymer prepared in Example 1 as a photoresist film-forming resin to form a photoresist composition of the present invention.

[0032] Figure 8This is the preparation method of the bonding type photoresist and the blended type photoresist of the present invention.

[0033] Fig. 9 The AFM and SEM images are of the photolithographic patterns obtained after photolithography and development of the blended photoresist of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0035] The synthetic route of the copolymer synthesized in each embodiment, namely the PAG-bonded photoresist film-forming resin, is shown in the attached Figure 1 As shown, the copolymers synthesized in each embodiment are formed by adding monomers of tetrahydrofurfuryl methacrylate, 2-isopropyl-2-adamantyl methacrylate, methacrylic acid and 4-(vinyl)benzenesulfonium triphenylsulfonium salt, adding a RAFT agent and an initiator, and performing RAFT active free radical polymerization. Through this method, the PAG bond is connected to the polymer chain, so that during photolithography, the photoacid generated is no longer randomly dispersed, and the diffusion of the photoacid is limited to a certain distance, which is beneficial to improving the photolithography resolution and reducing the edge roughness.

[0036] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, and the purpose and effects of the present invention will become more apparent.

[0037] The test methods and conditions of the copolymers prepared in the following examples are as follows:

[0038] The characteristic functional groups of each copolymer were characterized by a Nicolet iS50 infrared spectrometer. The structure of the copolymer is 1 H-NMR characterization revealed that 1 H-NMR characterization was performed on a DD2-600 spectrometer instrument, and the deuterated reagent was DMSO-d6. The thermal properties of the copolymers were characterized by thermogravimetric analyzer and differential scanning calorimeter; thermal analysis was performed using a TA Q500 thermogravimetric analyzer (TGA) in the temperature range of 50 to 500°C at a heating rate of 10°C / min, and thermal analysis was performed using a TA Q200 differential scanning calorimeter (DSC) at a rate of 60 to 160°C. The morphology of the photolithographic pattern was characterized using a MultiMode atomic force microscope in tapping mode.

[0039] Example 1

[0040] Take 4.6869g of tetrahydrofurfuryl methacrylate (molecular weight 170.206, about 0.02754mol), 0.5926g of methacrylic acid (molecular weight 86.089, about 0.00688mol), 9.0314g of 2-isopropyl-2-methacrylate adamantyl ester (molecular weight 262.39, about 0.03442mol), 3.6891g of 4-(vinyl)benzenesulfonium triphenylsulfonium salt (molecular weight 446.59, about 0.0083mol), 0.0569g of RAFT agent 2-cyano- 2-Propylbenzodisulfide (CPDB) (molecular weight 221.34, about 0.000257 mol) and 37 g of solvent DMF (molecular weight 73.095) were added to a 100 mL brown round-bottom flask, and nitrogen was passed into the flask for 20 minutes. 0.0127 g of initiator AIBN (azobisisobutyronitrile, molecular weight 164.208, about 0.00008 mol) was dissolved in 5 g of DMF to form an initiator solution. When the temperature in the round-bottom flask was raised to 60°C, the initiator solution was injected into the flask. After one hour of reaction, the temperature was raised to 65°C and the reaction was continued for 19 hours. After the reaction was completed, 300 mL of water was used to precipitate to obtain a pink solid, which was then washed with 300 mL of n-hexane and then dried in an oven at 70°C. The infrared spectrum of the copolymer synthesized by the RAFT method is shown in FIG. Figure 2 As shown in the NMR spectrum Figure 3 shown.

[0041] Figure 2 The infrared spectrum of the copolymer synthesized in this example is shown, wherein 3600-3400cm -1 The OH stretching vibration absorption peaks of sulfonate ions and carboxyl groups are at 2910 cm -1 The peak at 1650cm is the CH stretching vibration peak on adamantane; -1 The stretching vibration peak of C=O of carboxyl group; 1450cm -1 Nearby is the stretching vibration peak of the benzene ring skeleton. Figure 3 The NMR spectrum of the copolymer synthesized in this example is shown, and the characteristic peaks of each monomer are as follows: the signal at 12.5ppm comes from the proton of the carboxyl group in MAA; the signal at 7.5-8ppm comes from the aromatic proton of VBS-TPS; the signal at 3.6-4ppm comes from the proton of the carbon atom bound to oxygen in THFMA; the signal at 1.5ppm comes from the isopropyl group connected to the adamantane part in IAdMA. The above analysis results confirm that the synthesis of the copolymer is successful.

[0042] Figure 4The left figure shows the TGA curve of the copolymer synthesized in this example. It can be seen from the curve that the polymer of Example 1 begins to thermally decompose at around 170°C, proving that the polymer has good thermal stability and meets the temperature requirements of conventional pre- and post-baking. When the temperature is further raised to 500°C, the residual carbon content of the copolymer after thermal decomposition is as high as 10%, which is mainly due to the high benzene ring content in VBS-TPS. The benzene ring has a high carbon density and cannot form volatile components. Figure 4 The figure on the right shows the DSC curve of the copolymer synthesized in this example. Its glass transition temperature is around 135°C. Since VBS-TPS contains benzene rings, it is beneficial to improve rigidity and steric hindrance, hindering the movement of polymer chain segments, thereby making T g In general, the copolymer prepared in this example can meet the thermal performance requirements of the photoresist resin.

[0043] Figure 5 The sensitivity curve of the copolymer synthesized in this example formulated into a photoresist is shown. The sensitivity of the PAG-bonded film-forming resin can be improved by controlling the loading amount of the bonded PAG.

[0044] Figure 6 The acid diffusion length curve of the copolymer synthesized in this example is shown. By combining the anion part of BS-TBS with the polymer, the free volume of PAG can be reduced, the migration rate of the photoacid can be effectively reduced, the diffusion range of the proton acid can be limited, and the acid diffusion length can be effectively controlled, which is beneficial to reduce the line edge roughness (LER) and improve the resolution.

[0045] The copolymer prepared in this example is used as a photoresist film-forming resin to prepare a photoresist composition, and a development test is performed. The photoresist composition is prepared as follows: the copolymer used as a photoresist film-forming resin is mixed with a solvent, wherein the film-forming resin accounts for 5-30% by weight of the photoresist composition, and the photoresist composition is obtained after magnetic stirring for 24 hours.

[0046] The photoresist composition prepared above was spin-coated on a silicon wafer and pre-baked at 110°C for 90 seconds. The mask was placed on the baked sample and the exposure dose was 105 mJ / cm 2 After the exposure is completed, the sample is post-baked at 100°C for 30 seconds, and then placed in a 2.38% tetramethylammonium hydroxide developer for development. The developer is washed away with deionized water, and the obtained pattern is as follows: Figure 7 As shown in the figure, it can be seen that the edges of the photolithography pattern are clear and the imaging effect is excellent, which confirms that the photoresist film-forming resin prepared by the present invention can indeed reduce the phenomenon of acid diffusion and phase separation as well as line width roughness, and improve the resolution and imaging effect of the photoresist due to the PAG bonded in the copolymer chain.

[0047] Example 2

[0048] 4.9400g of tetrahydrofurfuryl methacrylate, 0.6246g of methacrylic acid, 9.5191g of 2-isopropyl-2-methyl acrylate adamantyl ester, 2.9163g of 4-(vinyl)benzenesulfonium triphenylsulfonium salt, 0.0584g of RAFT agent CPDB and 37g of DMF were added to a 100mL brown flask, and nitrogen was passed through for 20min. 0.0130g of AIBN was dissolved in 5g of DMF, and the above solution was injected into the round-bottom flask when the temperature was raised to 60°C. After one hour of reaction, the temperature was raised to 65°C, and the reaction was continued for 19h. After the reaction was completed, 300mL of water was used to precipitate the solid, which was then washed three times with 300mL of n-hexane and dried in an oven at 70°C to obtain a copolymer.

[0049] Preparation and development test of photoresist composition. The mass percentage of each component is as follows: 10% of the copolymer prepared in this embodiment, i.e., photoresist film-forming resin, and 90% of solvent, which is a mass ratio, and magnetic stirring is performed for 24 hours to fully dissolve to obtain a photoresist composition.

[0050] The photoresist composition was spin-coated on the silicon wafer and pre-baked at 110°C for 90 seconds. The mask was placed on the baked sample and the exposure was 105 mJ / cm 2 After the exposure is completed, the sample is post-baked at 100°C for 30 seconds, and then the sample is placed in a 2.38% tetramethylammonium hydroxide developer for development, and the developer is washed away with deionized water to obtain a photolithographic pattern. The photolithographic pattern obtained in this embodiment has clear edges, which is equivalent to the effect of Example 1.

[0051] Example 3

[0052] 5.2220g of tetrahydrofurfuryl methacrylate, 0.6603g of methacrylic acid, 10.0625g of 2-isopropyl-2-methylpropenoic acid adamantyl ester, 2.0552g of 4-(vinyl)benzenesulfonium triphenylsulfonium salt, 0.0600g of RAFT agent and 37g of DMF were added to a 100mL brown flask and purged with nitrogen for 20min. 0.0134g of AIBN was dissolved in 5g of DMF. When the temperature in the round-bottom flask was raised to 60°C, the above solution was injected. After one hour of reaction, the temperature was raised to 65°C and the reaction was continued for 19h. After the reaction was completed, 300mL of water was used to precipitate the solid, which was then washed three times with 300mL and dried in an oven at 70°C.

[0053] Preparation and development test of photoresist composition The mass percentage of each component is as follows: 10% of the copolymer synthesized by RAFT method in this embodiment, i.e., photoresist film-forming resin, and 90% of solvent, and magnetic stirring is performed for 24 hours to fully dissolve to obtain a photoresist composition.

[0054] The photoresist composition was spin-coated on the silicon wafer and pre-baked at 110°C for 90 seconds. The mask was placed on the baked sample and the exposure was 105 mJ / cm 2 After the exposure is completed, the sample is post-baked at 100°C for 30 seconds, and then the sample is placed in a 2.38% tetramethylammonium hydroxide developer for development, and the developer is washed away with deionized water to obtain a photolithographic pattern. The photolithographic pattern obtained in this embodiment has clear edges, which is equivalent to the effect of Example 1.

[0055] Example 4

[0056] Take 5.5381g of tetrahydrofurfuryl methacrylate, 0.7003g of methacrylic acid, 10.6718g of 2-isopropyl-2-methylacrylate adamantyl ester, 1.0898g of 4-(vinyl)benzenesulfonium triphenylsulfonium salt, 0.0618g of RAFT agent and 37g of DMF and add them to a 100mL brown flask, pass nitrogen for 20min, take 0.0138g of AIBN and dissolve it in 5g of DMF, inject the above solution when the temperature in the round-bottom flask rises to 60℃, react for one hour, heat it to 65℃, and continue to react for 19h. After the reaction is completed, precipitate with 300mL of water to obtain a solid, continue to wash it with 300mL of n-hexane three times, and dry it in an oven at 70℃.

[0057] Preparation and development test of photoresist composition The mass percentage of each component is as follows: 10% of the copolymer synthesized by RAFT method in this embodiment, i.e., photoresist film-forming resin, and 90% of solvent, and magnetic stirring is performed for 24 hours to fully dissolve to obtain a photoresist composition.

[0058] The photoresist composition was spin-coated on the silicon wafer and pre-baked at 110°C for 90 seconds. The mask was placed on the baked sample and the exposure was 105 mJ / cm 2 After the exposure is completed, the sample is post-baked at 100°C for 30 seconds, and then the sample is placed in a 2.38% tetramethylammonium hydroxide developer for development, and the developer is washed away with deionized water to obtain a photolithographic pattern. The photolithographic pattern obtained in this embodiment has clear edges, which is equivalent to the effect of Example 1.

[0059] Embodiment 5-7

[0060] The feed ratio is shown in Table 1, and the others are the same as those in Example 1. The test results and the photoresist pattern obtained by the final photoresist have clear edges, which are comparable to those in Example 1.

[0061] As shown in Tables 1 and 2 below, the dosage and actual composition of the copolymers synthesized in Examples 1 to 4 of the present invention are shown. From the comparison of the data in the tables, it can be seen that the actual composition is basically consistent with the dosage, which is basically within a reasonable error range, which also reflects that the polymerization of the preparation method of the present invention is successful.

[0062] Table 1 Feeding conditions of the synthetic copolymers in each embodiment

[0063]

[0064] Table 2 Actual composition of the copolymers synthesized in each embodiment

[0065]

[0066] Comparative Example 1

[0067] Compared with the photoresist prepared by the PAG-bonded resin of each embodiment of the present invention, this comparative example uses a film-forming resin without PAG bonded thereto and a common blend of PAG, and mixes them with a solvent to form a photoresist. The differences in the process of preparing the photoresist composition between each embodiment and this comparative example are as follows: Figure 8 As shown, the "blended photoresist" in the left figure refers to the photoresist composition of this comparative example, which is formed by physically blending a film-forming resin, PAG and a solvent ("solvent" in the figure); the formation of the photoresist composition of each embodiment is shown in the "bonded photoresist" in the right figure, which is formed by mixing the PAG bonded photoresist film-forming resin and solvent ("solvent" in the figure) prepared in each embodiment.

[0068] The photoresist preparation method of this comparative example is as follows:

[0069] 1) Synthesis of film-forming resin without PAG bonding:

[0070] 9.8251g of tetrahydrofurfuryl methacrylate, 1.2424g of methacrylic acid, 18.9326g of 2-isopropyl-2-methylacrylate adamantyl ester, 0.1065g of RAFT agent CPDB and 37g of DMF were added to a 100mL brown flask, and nitrogen was passed for 20 minutes. 0.0237g of AIBN was dissolved in 5g of DMF, and the above solution was injected into the round-bottom flask when the temperature was raised to 60°C. After one hour of reaction, the temperature was raised to 65°C, and the reaction was continued for 19 hours. After the reaction was completed, 300mL of water was used to precipitate the solid, which was then washed three times with 300mL of n-hexane and dried in an oven at 70°C to obtain a copolymer.

[0071] 2) Blending to form photoresist:

[0072] The mass percentage of each component is as follows: 10% of the film-forming resin without PAG synthesized in the above step 1), 0.5% of PAG, and 89.5% of solvent are mixed and magnetically stirred for 24 hours to fully dissolve to obtain the photoresist composition of this comparative example.

[0073] 3) The photoresist composition of this comparative example was spin-coated on a silicon wafer, pre-baked at 110°C for 90 seconds, and the mask was covered on the baked sample. The exposure metering was 51 mJ / cm2 After the exposure is completed, the sample is post-baked at 100°C for 30 seconds, and then placed in a 2.38% tetramethylammonium hydroxide developer for development. The developer is washed away with deionized water, and the obtained pattern is as follows: Fig. 9 As shown in the figure, it can be seen that the lithography pattern has poor morphology, rough edges, and high line width roughness, which is consistent with Figure 7 The comparison further proves the advantage of the present invention in bonding PAG to the film-forming resin by RAFT method.

[0074] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A PAG-bonded photoresist film-forming resin, characterized in that: The PAG bonded photoresist film-forming resin consists of four components: tetrahydrofurfuryl methacrylate, 2-isopropyl-2-adamantyl methacrylate, methacrylic acid and 4-(vinyl)benzenesulfonium triphenylsulfonium salt.

2. A PAG bonded photoresist film-forming resin according to claim 1, characterized in that: The structural formula of the PAG-bonded photoresist film-forming resin is as follows: Among them, x:y:z:n=30-45:40-60:5-15:3-15.

3. A method for preparing the PAG bonded photoresist film-forming resin according to any one of claims 1 to 2, characterized in that: The reversible addition-fragmentation chain transfer polymerization method comprises the following steps: 1) adding tetrahydrofurfuryl methacrylate, methacrylic acid, 2-isopropyl-2-adamantyl methacrylate, 4-(vinyl)benzenesulfonic acid triphenylsulfonium salt, a RAFT agent and a first solvent into a reaction vessel, passing nitrogen, raising the temperature to a first temperature zone, injecting an initiator, initiating the reaction and raising the temperature to a second temperature zone; 2) Under sealed conditions, the reaction temperature is maintained in the second temperature zone to continue the reaction. After the reaction is completed, the solid is precipitated with water to obtain a solid, which is washed with n-hexane and then dried in an oven to obtain the PAG-bonded photoresist film-forming resin.

4. The method for preparing the PAG bonded photoresist film-forming resin according to claim 3, characterized in that: In step 1), nitrogen is passed for 20-40 minutes and the reaction is initiated for 1 to 1.5 hours; in step 2), the reaction is continued for 19 to 22.5 hours, and the drying temperature is 60 to 80° C.; The first temperature zone is in the temperature range of 60-70°C, and the second temperature zone is in the temperature range of 65-75°C.

5. The method for preparing the PAG bonded photoresist film-forming resin according to claim 3, characterized in that: The initiator is an azo free radical initiator or a peroxide free radical initiator. The azo free radical initiator is selected from any one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, etc.; the peroxide free radical initiator is selected from any one of dibenzoyl peroxide, tert-butyl hydroperoxide, benzoic acid hydroperoxide, etc.; The RAFT agent is 2-(dodecyl trithiocarbonate)-2-methylpropionic acid, 4-cyano-4- Any one of [(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 4-cyano-4-(phenylcarbonylthio)pentanoic acid, 2-(dodecylthiocarbonylthiothiothio)propanoic acid, 2-phenyl-2-propylbenzodisulfide, 2-cyano-2-propylbenzodisulfide, 2-cyano-2-propyldodecyl trithiocarbonate, 2-cyano-2-propyldodecyl trithiocarbonate, and 1-(methoxycarbonyl)ethylphenyl dithioate.

6. The method for preparing the PAG bonded photoresist film-forming resin according to claim 3, characterized in that: The first solvent is one or more of N,N-dimethylformamide, propylene glycol methyl ether acetate, 1,4-dioxane, and N-methylpyrrolidone.

7. The method for preparing the PAG bonded photoresist film-forming resin according to claim 3, characterized in that: The solid content of the entire reaction system formed in step 1) is 20-40%; wherein the molar ratio of each component satisfies: Single 250~350 RAFT agent 0.5~1.5 Initiator 0.2~0.5 The monomers include tetrahydrofurfuryl methacrylate, methacrylic acid, 2-isopropyl-2-adamantyl methacrylate, and 4-(vinyl)benzenesulfonic acid triphenylsulfonium salt, and their added molar ratio satisfies: 30-45:40-60:5-15:3-15.

8. A photoresist composition, characterized in that: The photoresist composition is formed by stirring and mixing the PAG-bonded photoresist film-forming resin described in claim 1 or 2 and a second solvent, wherein the mass fraction of the photoresist film-forming resin in the photoresist composition is 5%-30%.

9. A photoresist composition according to claim 8, characterized in that: The second solvent is selected from any one or more of propylene glycol methyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, ethyl acetate, ethylene glycol monomethyl ether acetate, tetrahydrofuran, acetone, cyclohexanone, N,N-dimethylformamide or methanol.

10. A method for forming a photolithographic pattern, characterized in that: The photoresist composition according to claim 8 or 9 is used to coat the photoresist composition on a substrate to be photolithographically processed, and then pre-baked, a mask is placed on the photoresist composition, and then exposed, post-baked, developed, and cleaned with deionized water to obtain the photolithographic pattern.

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