PAG bonding type photosensitive photoresist resin and preparation method thereof

Abstract

The invention discloses PAG (Polyacrylamide) keyed photosensitive photoresist resin as well as a preparation method and application thereof. The photoresist resin is represented by the following formula. The PAG bonded resin is prepared by the following reaction processes: 1) carrying out RAFT polymerization reaction on p-acetoxystyrene, p-styrene sulfonyl imide trifluoromethyl potassium salt and an RAFT chain transfer agent under the action of an initiator to obtain an intermediate I, 2) carrying out hydrolysis reaction on the intermediate I to obtain an intermediate II, 3) introducing a protecting group to the intermediate II and di-tert-butyl dicarbonate for reaction to obtain an intermediate III; and 4) carrying out ion exchange reaction on the intermediate III and triphenyl sulfonium bromide. According to the invention, PAG is bonded into a resin skeleton, and the problems of poor compatibility between PAG and resin, phase separation, uneven PAG distribution and the like are improved. Therefore, the resolution ratio of the photoresist prepared from the resin is improved and the photoetching effect is excellent due to the fact that the photo-generated acid is constrained by a polymer main chain and the diffusion is limited. # imgabs0 #

Description

Technical Field

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

[0002] Photolithography is a process technology that uses the photochemical reaction principle of photoresist and chemical and physical etching methods to transfer the pattern on the mask to the wafer. Photoresist, also known as photoresist, refers to an etching-resistant photosensitive material whose solubility changes significantly when exposed to ultraviolet light, electron beam or other irradiation or radiation. Photolithography is an important factor in limiting the size of integrated circuit devices, and photoresist materials play a decisive role in realizing the next generation of photolithography.

[0003] According to the chemical reaction mechanism, photoresists can be divided into positive photoresists and negative photoresists. Positive photoresists refer to photoresists in which, after exposure and development in the photolithography process, the exposed part of the coating is dissolved in the developer while the unexposed part is retained to form an image; negative photoresists are the opposite of positive photoresists, in which the unexposed part is dissolved while the exposed part forms an image.

[0004] The traditional photolithography resolution follows the Rayleigh formula: d = kλ / NA, where d is the minimum line width of the photolithography, k is the process coefficient, λ is the exposure wavelength in the photolithography process, and NA is the aperture size. Improving the minimum line width in the traditional photolithography process can be achieved by increasing the aperture of the lens of the photolithography equipment or by reducing the exposure wavelength used in the photolithography process. According to the different wavelengths of the exposure light source, photoresists can be divided into ultraviolet, deep ultraviolet and extreme ultraviolet photoresists.

[0005] Compared with ultraviolet light, deep ultraviolet light has a lower intensity. In order to meet the photosensitivity requirements, deep ultraviolet photoresists are generally chemically amplified photoresists. The working mechanism of chemically amplified photoresists is that the photoacid generator decomposes to produce acid during the exposure process. During the post-baking process, the acid catalyzes the acid-labile groups in the polymer resin to undergo a chemical reaction. After the catalytic reaction is completed, the acid is released again to continue to catalyze the reaction of other acid-labile groups until all acid-labile groups of the polymer resin in the exposed area are completely removed. Therefore, a small amount of photoacid generator can completely remove the acid-labile groups of the polymer resin after exposure, thereby changing the solubility of the polymer resin in the developer and achieving the effect of chemical amplification. This reduces the requirements for the photoacid generator content and exposure energy in the photoresist.

[0006] Chemically amplified photoresists are mainly composed of polymer resins, photoacid generators and solvents. The polymer resin is the skeleton of the photoresist and determines the basic properties of the photoresist, such as hardness, flexibility, and adhesion. The photoacid generator (PAG) produces a trace amount of acid during the exposure process to react with the main resin for deprotection, increasing the solubility difference between the exposed area and the non-exposed area in the developer. The solvent is the largest component in the photoresist, which keeps the photoresist in a liquid state and has almost no effect on the chemical properties of the photoresist.

[0007] The traditional photoresist system is a blend of PAG and polymer resin. Since PAG is usually a small molecule compound, it has inherent incompatibility with polymer resin, which can cause problems such as phase separation, uneven distribution of PAG in the photoresist film, segregation of PAG to the upper layer of the photoresist film during the pre-bake process, and migration of photogenerated acid during the post-bake process. This leads to uneven acid-catalyzed photochemical reactions in the exposure area, resulting in greater roughness of the edges of the photolithographic pattern lines and lower resolution. Photoresist polymer resins are mainly synthesized by traditional free radical polymerization, which is prone to side reactions such as free radical coupling, disproportionation, and chain transfer during the polymerization process. In addition, due to the large difference in the reactivity of PAG and other monomers, the composition and molecular weight of the synthesized polymer are difficult to control. Summary of the invention

[0008] In order to overcome the above problems, the present invention provides a PAG-bonded photosensitive photoresist resin and a preparation method thereof; the photoresist prepared by using the PAG-bonded photosensitive photoresist resin of the present invention has excellent photolithography effect.

[0009] The present invention is achieved through the following technical solutions.

[0010] The present invention first provides a PAG-bonded photosensitive photoresist resin, the structural formula of which is as follows:

[0011]

[0012] Among them, x:y:z=(1~70):(20~80):(1~30).

[0013] The present invention also provides a method for preparing the above-mentioned PAG-bonded photosensitive photoresist resin, and the synthetic route of the preparation method is:

[0014]

[0015] Among them, n=x+y; n:z=(2~99):1, x:y=(0.01-3.5):1.

[0016] The method comprises the following steps:

[0017] (1) dispersing p-acetoxystyrene, p-styrenesulfonyl imide trifluoromethyl potassium salt and a RAFT chain transfer agent in a first solvent, adding an initiator to carry out a RAFT polymerization reaction, and after the reaction is completed, dripping the reaction solution into a second solvent, filtering to obtain a solid precipitate, and then dispersing the solid precipitate in the first solvent, and then dripping it into a third solvent, filtering and drying to obtain an intermediate I;

[0018] (2) dispersing the intermediate I and the first base in the first solvent and the second solvent to cause a hydrolysis reaction. After the reaction is completed, adding an acid to adjust the pH of the reaction solution, standing the solution to separate into layers, then dropping the organic phase of the reaction solution into the second solvent, filtering and drying to obtain the intermediate II; assuming that the added moles of acetoxystyrene and trifluoromethyl potassium salt of styrenesulfonyl imide in step (1) are n and z, respectively, then the added molar ratio here satisfies the intermediate I: first base = 1: (n-3n);

[0019] (3) Dispersing the intermediate II, the second base and di-tert-butyl dicarbonate in the first solvent to introduce a protecting group; the molar ratio of the addition satisfies the intermediate II: the second base: di-tert-butyl dicarbonate = 1: (0.05n-0.2n): (0.2-0.99n);

[0020] (4) adding the reaction solution dropwise into the third solvent, filtering to obtain a solid precipitate, and then dispersing the solid precipitate in the first solvent;

[0021] (5) Repeat step (4) twice, then add the solution dropwise into a third solvent, filter and dry to obtain intermediate III;

[0022] (6) dispersing the intermediate III and triphenylsulfonium bromide in the first solvent and the second solvent to cause an ion exchange reaction, wherein the molar ratio of the addition satisfies the intermediate III:triphenylsulfonium bromide=1:(z~2z);

[0023] (7) After the reaction is completed, the solution is allowed to stand for stratification, and the organic phase of the reaction solution is washed three times with the second solvent;

[0024] (8) adding the organic phase of the reaction solution dropwise into the third solvent, filtering to obtain a solid precipitate, and then dispersing the solid precipitate in the first solvent;

[0025] (9) Repeat step (8) twice, then dropwise add the solution into the third solvent, filter and dry to obtain a PAG-bonded photosensitive photoresist resin.

[0026] Furthermore, in step (1), the molar ratio of p-acetoxystyrene to p-styrenesulfonyl imide trifluoromethyl potassium salt is (2-99):1, the molar ratio of p-acetoxystyrene to RAFT chain transfer agent is (30-100):1, and the molar ratio of p-acetoxystyrene to initiator is (30-300):1.

[0027] Further, the RAFT chain transfer agent described in step (1) is any one of 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 4-cyano-4-(phenylcarbonylthio)pentanoic acid, 2-phenyl-2-propylbenzodisulfide, 2-cyano-2-propylbenzodisulfide, 2-cyano-2-propyldodecyltrithiocarbonate or 1-(methoxycarbonyl)benzodithioic acid ethyl ester.

[0028] Furthermore, the initiator described in step (1) is an azo free radical initiator or a peroxide free radical initiator, wherein the azo initiator is any one of azobisisobutyronitrile, azobisisoheptanenitrile or dimethyl azobisisobutyrate, and the peroxide free radical initiator is any one of dibenzoyl peroxide, tert-butyl hydroperoxide or benzoic acid hydroperoxide.

[0029] Furthermore, the first solvent is one or more of dichloromethane, chloroform, dioxane, tetrahydrofuran, N,N-dimethylformamide, propylene glycol methyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, ethyl acetate, ethylene glycol monomethyl ether acetate, acetone, cyclohexanone or methanol, the second solvent is water, and the third solvent is any one of n-hexane, petroleum ether or cyclohexane.

[0030] Furthermore, the first base is any one of sodium hydroxide, lithium hydroxide, potassium hydroxide or ammonia water, and the second base is any one of 4-dimethylaminopyridine, lithium carbonate, calcium carbonate, sodium carbonate, potassium carbonate, potassium tert-butoxide or sodium methoxide; the acid used to adjust the pH of the reaction solution in step (2) is any one of hydrochloric acid, phosphoric acid, formic acid, acetic acid or aminoacetic acid.

[0031] Furthermore, the RAFT polymerization reaction temperature in step (1) is 40-100°C, and the time is 5-24 hours; the hydrolysis reaction temperature in step (2) is 20-70°C, and the time is 2-24 hours; the introduction of protective groups in step (3) is at a temperature of 20-60°C, and the time is 2-24 hours; the ion exchange reaction temperature in step (6) is at a temperature of 20-60°C, and the time is 2-24 hours.

[0032] The present invention also provides a photoresist, which is formed by stirring and mixing the above-mentioned PAG bonded photosensitive photoresist 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.

[0033] The present invention also provides a method for forming a photolithography pattern, using the above-mentioned photoresist, coating the photoresist on a substrate to be photolithographically processed, such as a silicon wafer, and performing pre-baking. A mask is then covered on the photoresist, and the photolithography pattern is obtained by exposure, post-baking and development.

[0034] More specifically, the method for forming a photolithography pattern is as follows: spin-coat the above-mentioned photoresist on the substrate to be photolithography, pre-bake it at 100°C for 60s, cover the baked photoresist with a mask, and expose it through the mask with 254nm ultraviolet rays. After the exposure is completed, post-bake it at 100°C for 60s, and then develop it in a 2.38% tetramethylammonium hydroxide developer, and then wash away the developer with deionized water to obtain a photolithography pattern.

[0035] The beneficial effects of the present invention are mainly reflected in the following aspects.

[0036] 1. The present invention prepares the photoresist resin by a reversible addition-fragmentation chain transfer (RAFT) polymerization method, wherein a RAFT chain transfer agent with a high chain transfer coefficient is added to a conventional free radical polymerization, and reversible addition-fragmentation chain transfer is continuously performed between the growing chain free radical and the dormant chain, so that the active free radical concentration in the reaction system is kept at a relatively low level, and side reactions such as coupling or disproportionation termination between molecular chains are reduced, thereby achieving controllable active free radical polymerization, controllable composition and molecular weight of the synthesized polymer, and uniform and controllable composition of the polymer resin.

[0037] 2. In addition, the present invention also realizes the connection of PAG bonds into the resin, and the bonding of the photoacid generator (PAG) unit into the photoresist polymer resin skeleton, which effectively improves the problems of poor compatibility between PAG and resin, phase separation, and uneven distribution of PAG. Moreover, the diffusion of the photogenerated acid generated after exposure is restricted due to the constraints of the polymer main chain, thereby reducing the edge roughness of the imaging pattern and improving the resolution of the photoresist. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the infrared spectrum of the PAG-bonded photosensitive photoresist resin in Example 1 of the present invention.

[0039] Figure 2 This is the H-NMR spectrum of the PAG-bonded photosensitive photoresist resin in Example 1 of the present invention.

[0040] Figure 3 This is the sensitivity curve of the photoresist prepared by the PAG-bonded photosensitive photoresist resin in Example 1 of the present invention.

[0041] Figure 4 This is the acid diffusion length curve of the photoresist prepared by the PAG-bonded photosensitive photoresist resin in Example 1 of the present invention.

[0042] Figure 5 This is an optical microscope pattern of the photolithography morphology obtained by using the photoresist prepared with the PAG-bonded photosensitive photoresist resin in Example 1 of the present invention.

[0043] Figure 6 This is an atomic force microscope pattern of the lithography morphology obtained from the photoresist prepared from the PAG-bonded photosensitive photoresist resin in Example 1 of the present invention. DETAILED DESCRIPTION

[0044] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0045] Each embodiment of the present invention prepares a PAG-bonded photosensitive photoresist resin according to the synthetic route of the following reaction formula. The preparation process mainly includes: acetoxystyrene, trifluoromethyl potassium salt of styrenesulfonyl imide and RAFT chain transfer agent undergo RAFT polymerization reaction under the action of an initiator to form intermediate I; intermediate I undergoes hydrolysis reaction in alkali solution to obtain intermediate II; intermediate II and di-tert-butyl dicarbonate undergo an introduction of protective group reaction in alkali solution to obtain intermediate III; intermediate III and triphenylsulfonium bromide undergo an ion exchange reaction to obtain the PAG-bonded photosensitive photoresist resin. Through this method, the PAG bond is connected to the polymer chain, so that during photolithography, the generated photoacid 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.

[0046]

[0047] 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.

[0048] Example 1

[0049] The specific steps of preparing the PAG bonded photosensitive photoresist resin in this embodiment are as follows:

[0050] (1) Disperse 5.42 g of p-acetoxystyrene, 2.31 g of p-styrenesulfonyl imide trifluoromethyl potassium salt and 0.24 g of RAFT chain transfer agent 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid in 8.70 g of solvent N,N-dimethylformamide, pass nitrogen gas for protection, heat to 70°C, and add 3.30 g of 0.06 g of initiator azobisisobutyronitrile in N,N-dimethylformamide is reacted at 70°C for 8 hours; after the reaction, the reaction solution is added dropwise to 500 ml of water, filtered to obtain a solid precipitate, and then the solid precipitate is dissolved in 50 ml of tetrahydrofuran, then added dropwise to 500 ml of n-hexane, filtered and dried under reduced pressure to obtain intermediate I; in this step, the addition ratio of each main material satisfies: the molar ratio of p-acetoxystyrene to p-styrenesulfonyl imide trifluoromethyl potassium salt is (5.10:1), the molar ratio of p-acetoxystyrene to RAFT chain transfer agent is (48:1), and the molar ratio of p-acetoxystyrene to initiator is (96:1).

[0051] (2) Disperse 5.90 g of intermediate I and 2.17 g of sodium hydroxide in 39.0 g of tetrahydrofuran and 26.9 g of water, and react at 40° C. for 6 h. After the reaction, add hydrochloric acid to adjust the pH of the reaction solution to 7, let stand until the solution is separated, then add the organic phase of the reaction solution dropwise into 500 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate II.

[0052] (3) Disperse 2.36 g of intermediate II, 0.15 g of 4-dimethylaminopyridine and 1.79 g of di-tert-butyl dicarbonate in 25.69 g of acetone and react at 25 °C for 6 h;

[0053] (4) The reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of acetone;

[0054] (5) Repeat step (4) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate III;

[0055] (6) Disperse 2.48 g of intermediate III and 0.65 g of triphenylsulfonium bromide in 37.60 g of dichloromethane and 15.20 g of water, and react at 25 °C for 6 h;

[0056] (7) After the reaction is completed, the solution is allowed to stand for separation, and the organic phase of the reaction solution is washed three times with 25 ml of water;

[0057] (8) The organic phase of the reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of dichloromethane;

[0058] (9) Repeat step (8) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain a PAG-bonded photosensitive photoresist resin.

[0059] Example 2

[0060] The specific steps of preparing the PAG bonded photosensitive photoresist resin in this embodiment are as follows:

[0061] (1) 8.33 g of p-acetoxystyrene, 3.20 g of p-styrenesulfonyl imide trifluoromethyl potassium salt and 0.38 g of RAFT chain transfer agent 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid were dispersed in 14.10 g of solvent N,N-dimethylformamide, and the mixture was heated to 70° C. and dispersed in 3.90 g of 0.09 g of initiator azobisisobutyronitrile in N,N-dimethylformamide was reacted at 70°C for 8 h; after the reaction, the reaction solution was added dropwise to 500 ml of water, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 50 ml of tetrahydrofuran, then added dropwise to 500 ml of n-hexane, filtered and dried under reduced pressure to obtain intermediate I; in this step, the addition ratio of each main material satisfied: the molar ratio of p-acetoxystyrene to p-styrenesulfonyl imide trifluoromethyl potassium salt was (5.67:1), the molar ratio of p-acetoxystyrene to RAFT chain transfer agent was (48:1), and the molar ratio of p-acetoxystyrene to initiator was (96:1).

[0062] (2) Disperse 9.23 g of intermediate I and 3.46 g of sodium hydroxide in 36.2 g of tetrahydrofuran and 28.0 g of water, and react at 40° C. for 6 h. After the reaction, add hydrochloric acid to adjust the pH of the reaction solution to 7, let stand until the solution is separated, then add the organic phase of the reaction solution dropwise into 500 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate II.

[0063] (3) Disperse 2.74 g of intermediate II, 0.19 g of 4-dimethylaminopyridine and 2.23 g of di-tert-butyl dicarbonate in 30.10 g of acetone and react at 25 °C for 6 h;

[0064] (4) The reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of acetone;

[0065] (5) Repeat step (4) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate III;

[0066] (6) Disperse 2.88 g of intermediate III and 0.69 g of triphenylsulfonium bromide in 20.10 g of dichloromethane and 7.10 g of water, and react at 25 °C for 6 h;

[0067] (7) After the reaction is completed, the solution is allowed to stand for separation, and the organic phase of the reaction solution is washed three times with 25 ml of water;

[0068] (8) The organic phase of the reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of dichloromethane;

[0069] (9) Repeat step (8) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain a PAG-bonded photosensitive photoresist resin.

[0070] Example 3

[0071] The specific steps of preparing the PAG bonded photosensitive photoresist resin in this embodiment are as follows:

[0072] (1) 9.46 g of p-acetoxystyrene, 2.02 g of p-styrenesulfonyl imide trifluoromethyl potassium salt and 0.43 g of RAFT chain transfer agent 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid were dispersed in 12.80 g of solvent N,N-dimethylformamide, and the mixture was heated to 70° C. and dispersed in 5.20 g of 0.10 g of initiator azobisisobutyronitrile in N,N-dimethylformamide is reacted at 70°C for 8 hours; after the reaction, the reaction solution is added dropwise to 500 ml of water, filtered to obtain a solid precipitate, and then the solid precipitate is dissolved in 50 ml of tetrahydrofuran, then added dropwise to 500 ml of n-hexane, filtered and dried under reduced pressure to obtain intermediate I; in this step, the addition ratio of each main material satisfies: the molar ratio of p-acetoxystyrene and p-styrenesulfonimide trifluoromethyl potassium salt is (120:11.77), the molar ratio of p-acetoxystyrene and RAFT chain transfer agent is (120:2.5), and the molar ratio of p-acetoxystyrene and initiator is (120:1.25).

[0073] (2) Disperse 5.90 g of intermediate I and 2.58 g of sodium hydroxide in 28.4 g of tetrahydrofuran and 20.9 g of water, and react at 40° C. for 6 h. After the reaction, add hydrochloric acid to adjust the pH of the reaction solution to 7, let stand until the solution is separated, then add the organic phase of the reaction solution dropwise into 500 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate II.

[0074] (3) Disperse 3.08 g of intermediate II, 0.25 g of 4-dimethylaminopyridine and 2.89 g of di-tert-butyl dicarbonate in 21.80 g of acetone and react at 25 °C for 6 h;

[0075] (4) The reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of acetone;

[0076] (5) Repeat step (4) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate III;

[0077] (6) Disperse 3.78 g of intermediate III and 0.60 g of triphenylsulfonium bromide in 46.00 g of dichloromethane and 18.90 g of water, and react at 25 °C for 6 h;

[0078] (7) After the reaction is completed, the solution is allowed to stand for separation, and the organic phase of the reaction solution is washed three times with 25 ml of water;

[0079] (8) The organic phase of the reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of dichloromethane;

[0080] (9) Repeat step (8) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain a PAG-bonded photosensitive photoresist resin.

[0081] Example 4

[0082] The specific steps of preparing the PAG bonded photosensitive photoresist resin in this embodiment are as follows:

[0083] (1) 8.75 g of p-acetoxystyrene, 2.76 g of p-styrenesulfonyl imide trifluoromethyl potassium salt and 0.39 g of RAFT chain transfer agent 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid were dispersed in 14.00 g of solvent N,N-dimethylformamide, and the mixture was protected by nitrogen. The temperature was raised to 70° C. and the mixture was dispersed in 4.00 g of 0.09 g of initiator azobisisobutyronitrile in N,N-dimethylformamide is reacted at 70°C for 8 hours; after the reaction, the reaction solution is added dropwise to 500 ml of water, filtered to obtain a solid precipitate, and then the solid precipitate is dissolved in 50 ml of tetrahydrofuran, then added dropwise to 500 ml of n-hexane, filtered and dried under reduced pressure to obtain intermediate I; in this step, the addition ratio of each main material satisfies: the molar ratio of p-acetoxystyrene and p-styrenesulfonyl imide trifluoromethyl potassium salt is (120:17.39), the molar ratio of p-acetoxystyrene and RAFT chain transfer agent is (120:2.5), and the molar ratio of p-acetoxystyrene and initiator is (120:1.25).

[0084] (2) Disperse 5.61 g of intermediate I and 2.24 g of sodium hydroxide in 28.1 g of tetrahydrofuran and 21.1 g of water, and react at 40° C. for 6 h. After the reaction, add hydrochloric acid to adjust the pH of the reaction solution to 7, let stand until the solution is separated, then add the organic phase of the reaction solution dropwise into 500 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate II.

[0085] (3) Disperse 2.47 g of intermediate II, 0.18 g of 4-dimethylaminopyridine and 2.08 g of di-tert-butyl dicarbonate in 17.30 g of acetone and react at 25 °C for 6 h;

[0086] (4) The reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of acetone;

[0087] (5) Repeat step (4) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain intermediate III;

[0088] (6) Disperse 2.31 g of intermediate III and 0.54 g of triphenylsulfonium bromide in 43.80 g of dichloromethane and 27.70 g of water, and react at 25 °C for 6 h;

[0089] (7) After the reaction is completed, the solution is allowed to stand for separation, and the organic phase of the reaction solution is washed three times with 25 ml of water;

[0090] (8) The organic phase of the reaction solution was added dropwise to 200 ml of n-hexane, filtered to obtain a solid precipitate, and then the solid precipitate was dissolved in 20 ml of dichloromethane;

[0091] (9) Repeat step (8) twice, then add the reaction solution dropwise into 200 ml of n-hexane, filter and dry under reduced pressure to obtain a PAG-bonded photosensitive photoresist resin.

[0092] The PAG bonded photosensitive photoresist resin prepared in the above embodiments is used to prepare a photoresist: the PAG bonded photosensitive photoresist resin and a solvent are stirred and mixed to form a photoresist. The inventor found in the test of the photoresist that the mass fraction of the resin is 5%-30%, and the obtained photoresist has the same photolithography performance, and has the characteristics of clear photolithography morphology, few defects, etc. Only some application examples of the present invention are listed below for illustration.

[0093] Application Example 1

[0094] This application uses the PAG-bonded photosensitive photoresist resin prepared in Example 1 to prepare photoresist, and the preparation steps are as follows: 100 parts by weight of PAG-bonded photoresist resin, 600 parts by weight of propylene glycol monomethyl ether acetate and 300 parts by weight of ethyl lactate are mixed evenly, and filtered using a 0.22 μm filter to obtain the photoresist of this application example.

[0095] Application Example 2

[0096] The difference from Application Example 1 is that the PAG bonded photosensitive photoresist resin prepared in Example 2 is used to prepare the photoresist. The rest is the same as Application Example 1.

[0097] Application Example 3

[0098] The difference from Application Example 1 is that the PAG bonded photosensitive photoresist resin prepared in Example 3 is used to prepare the photoresist. The other steps are the same as those in Application Example 1.

[0099] Application Example 4

[0100] The difference from Application Example 1 is that the PAG bonded photosensitive photoresist resin prepared in Example 4 is used to prepare the photoresist. The rest is the same as Application Example 1.

[0101] Performance testing and evaluation

[0102] The structure of the PAG bonded photosensitive photoresist resin prepared in the above embodiments was characterized by infrared spectroscopy and nuclear magnetic hydrogen spectrum. In addition, the photoresist of each application example was subjected to the following tests, including the photoresist sensitivity test, the photoresist acid diffusion length test and the photolithography test. The details are as follows.

[0103] 1) IR and H-NMR characterization of PAG-bonded photosensitive photoresist resin.

[0104] 2) Photoresist sensitivity test

[0105] The photoresist of each application example was spin-coated on a silicon wafer to obtain a photoresist film with a thickness of 200 nm. After pre-baking at 100° C. for 60 seconds, the film was exposed to 254 nm ultraviolet light, and then post-exposure baked at 100° C. for 60 seconds. Then, a 2.38 wt % tetramethylammonium hydroxide aqueous solution was used for development at 23° C. for 10 seconds. The thickness change of the photoresist film was measured.

[0106] 3) Photoresist acid diffusion length test

[0107] First, a base polymer resin solution is spin-coated on a silicon wafer as the first film, and its thickness is measured. After pre-baking at 100°C for 60 seconds, the photoresist prepared in each application example is spin-coated on the first film. After pre-baking at 100°C for 60 seconds, it is exposed to 254nm ultraviolet light, and then baked at 100°C for 60 seconds after exposure. Then, it is developed at 23°C for 10 seconds using a 2.38wt% tetramethylammonium hydroxide aqueous solution. The thickness of the film on the silicon wafer after development is measured, and the acid diffusion length is the difference in thickness between the first film and the film after development.

[0108] The preparation process of the base polymer resin solution for the first layer of film is as follows:

[0109] (a) Preparation of base polymer resin:

[0110] (1) About 22.74 g of p-acetoxystyrene and about 1.02 g of 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid were added to a flask filled with nitrogen, and then 31 g of dioxane was added to the flask. After stirring evenly, the flask was heated to 70° C., and then a mixed solution of dioxane (5 g) and azobisisobutyronitrile (0.24 g) was slowly injected into the flask. The reaction was carried out at 70° C. for 8 hours, and the reaction was stopped;

[0111] (2) Then the reaction solution was added dropwise to a beaker containing n-hexane (500 ml) and stirred continuously to produce precipitation. The addition was completed in 30 minutes. After 1 hour, the stirring was stopped and the solid precipitate was obtained by filtration. The solid precipitate was placed in a vacuum drying oven at 100°C and dried for 24 hours to obtain polymerized para-acetoxystyrene;

[0112] (3) Add about 14.00 g of poly(p-acetoxystyrene) and about 7.26 g of sodium hydroxide into a flask, then add 60 ml of tetrahydrofuran and 45 ml of deionized water into the flask, stir evenly, and heat the flask to 40° C. React at 40° C. for 6 hours, stop the reaction, add hydrochloric acid dropwise to adjust the solution pH to 7, and let stand until the solution separates;

[0113] (4) The organic phase of the reaction solution was then added dropwise to a beaker containing deionized water (500 ml) and stirred continuously to produce a precipitate. The addition was completed in 30 minutes. After 1 hour, the stirring was stopped and the solid precipitate was obtained by filtration. The solid precipitate was placed in a vacuum drying oven at 65°C and dried for 24 hours to obtain poly(p-hydroxystyrene).

[0114] (5) Add about 9.00 g of poly(p-hydroxystyrene), about 0.92 g of 4-dimethylaminopyridine and about 10.63 g of di-tert-butyl dicarbonate into a flask, then add 120 ml of acetone into the flask, stir evenly and heat the flask to 25° C. React at 25° C. for 6 hours and then stop the reaction;

[0115] (6) The reaction solution was then added dropwise to a beaker containing n-hexane (500 ml) and stirred continuously to produce a precipitate. The addition was completed in 30 minutes. After 1 hour, stirring was stopped, and the solid precipitate was filtered and dissolved in 50 ml of acetone;

[0116] (7) Repeat step (6) twice, then add the reaction solution dropwise into a beaker containing n-hexane (500 ml) and stir continuously to produce a precipitate. The addition is completed in 30 minutes. After 1 hour, stop stirring, filter to obtain a solid precipitate, and place the solid precipitate in a vacuum drying oven at 65°C and dry for 24 hours to obtain a base polymer resin. The structural formula of the base polymer resin finally prepared is as follows:

[0117]

[0118] (b) Preparation of base polymer resin solution: 100 parts by weight of the base polymer resin prepared above was dissolved in 600 parts by weight of propylene glycol monomethyl ether acetate and 300 parts by weight of ethyl lactate, mixed well, and filtered using a 0.22 μm filter to prepare a base polymer resin solution.

[0119] 4) Photoresist lithography test

[0120] The photoresist of each application example was spin-coated on a silicon wafer to obtain a photoresist film with a thickness of 200 nm. After pre-baking at 100°C for 60 seconds, the film was exposed through a mask using 254nm ultraviolet rays, and then post-exposure baking was performed at 100°C for 60 seconds. Then, the film was developed using a 2.38wt% tetramethylammonium hydroxide aqueous solution at 23°C for 10 seconds. The pattern shape was observed.

[0121] The above test evaluation of the synthesis results of the PAG-bonded photoresist resin and the corresponding photoresist effect test results are as follows.

[0122] (1) Figure 1 The infrared spectrum of the PAG-bonded photosensitive photoresist resin in Example 1 is shown in FIG. 3450 cm -1 The broad absorption peak near 1760cm is the -OH stretching vibration peak; -1 The absorption peak at 1150cm corresponds to the C=O stretching vibration peak; -1 The absorption peak at 1370cm is the -COC- stretching vibration peak; -1 The absorption peak near 1325cm is the bending vibration peak of the methyl group in the tert-butyl group; -1 The absorption peak at 1660-1700cm is the stretching vibration peak of S=O; -1 There is no obvious C=C double bond absorption peak in the range, which confirms the successful synthesis of PAG-bonded photosensitive photoresist resin without residual monomers.

[0123] (2) Figure 2 As shown, this is the H NMR spectrum of the PAG-bonded photosensitive photoresist resin in Example 1, the signal peak of δ=9.00ppm is the hydrogen in the hydroxyl group, the signal peak of δ=7.69-7.91ppm is the hydrogen in the triphenylsulfide ion, the signal peak of δ=6.00-7.40ppm is the hydrogen on the benzene ring of the polymer side chain, the signal peak of δ=1.4-1.5ppm is the hydrogen of the tert-butyl group, and the remaining peaks are mainly from the hydrogen in the polymer main chain.

[0124] (3) Figure 3-4 Shown are the photoresist sensitivity curve and acid diffusion length curve in Application Example 1, respectively. Figure 3 It can be seen that the photoresist prepared by PAG bonded photoresist resin has high sensitivity. Figure 4 From the acid diffusion length curve of the photoresist, it can be seen that the acid diffusion length is small. By combining the anion part of the photoacid to the polymer, the free volume of PAG can be reduced, the migration rate of the photoacid can be effectively reduced, and the diffusion range of the proton acid can be limited, thereby effectively controlling the acid diffusion length, which is beneficial to reducing the line edge roughness (LER) and improving the resolution.

[0125] (4) Figure 5 This is an optical microscope image of the morphology of the photolithography pattern obtained by photolithography using the photoresist in Application Example 1. Figure 6 The photolithography atomic force microscope pattern obtained by the photoresist prepared by the PAG-bonded photosensitive photoresist resin in Example 1 of the present invention. It can be seen from the two figures that the line pattern formed after photolithography has a clear line morphology, fewer defects, and excellent photolithography effect. It is further confirmed that the PAG bonded to the resin polymer chain can effectively reduce the migration rate of the photoacid, limit the diffusion range of the proton acid, and then effectively control the acid diffusion length, which is conducive to reducing the line edge roughness and improving the resolution.

[0126] The above embodiments are intended to illustrate the essential content of the present invention, but are not intended to limit the protection scope of the present invention. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and protection scope of the technical solution of the present invention.

Claims

1. A PAG-bonded photosensitive photoresist resin, characterized in that: The structural formula of the PAG-bonded photosensitive photoresist resin is as follows: Among them, x:y:z=(1-70):(20-80):(1-30).

2. The method for preparing a PAG-bonded photosensitive photoresist resin according to claim 1, characterized in that: The synthetic route of the preparation method is as follows: Among them, n=x+y; n:z=(2~99):1, x:y=(0.01-3.5):

1.

3. The method for preparing a PAG-bonded photosensitive photoresist resin according to claim 2, characterized in that: The method comprises the following steps: (1) dispersing p-acetoxystyrene, p-styrenesulfonyl imide trifluoromethyl potassium salt and a RAFT chain transfer agent in a first solvent, adding an initiator to cause a RAFT polymerization reaction, and after the reaction is completed, dripping the reaction solution into a second solvent, filtering to obtain a solid precipitate, and then dispersing the solid precipitate in the first solvent, Then add it dropwise into the third solvent, filter and dry to obtain intermediate I; (2) dispersing the intermediate I and the first base in the first solvent and the second solvent to cause a hydrolysis reaction. After the reaction is completed, adding an acid to adjust the pH of the reaction solution, standing the solution to allow the solution to separate, then dropping the organic phase of the reaction solution into the second solvent, filtering and drying to obtain the intermediate II; (3) dispersing the intermediate II, the second base and di-tert-butyl dicarbonate in the first solvent to introduce a protecting group; (4) adding the reaction solution dropwise into the third solvent, filtering to obtain a solid precipitate, and then dispersing the solid precipitate in the first solvent; (5) Repeat step (4) for multiple times, then add the reaction solution dropwise into a third solvent, filter and dry to obtain intermediate III; (6) dispersing the intermediate III and triphenylsulfonium bromide in the first solvent and the second solvent to cause an ion exchange reaction; (7) After the reaction is completed, the solution is allowed to stand for separation, and the organic phase of the reaction solution is washed multiple times with the second solvent; (8) adding the organic phase of the reaction solution dropwise into the third solvent, filtering to obtain a solid precipitate, and then dispersing the solid precipitate in the first solvent; (9) Repeat the operation of step (8) for multiple times, then dropwise add the reaction solution into the third solvent, filter and dry to obtain a PAG-bonded photosensitive photoresist resin.

4. The method for preparing the PAG-bonded photosensitive photoresist resin according to claim 3, characterized in that: In step (1), the molar ratio of acetoxystyrene to trifluoromethyl potassium salt of styrenesulfonyl imide is (2-99):1, the molar ratio of acetoxystyrene to RAFT chain transfer agent is (30-100):1, and the molar ratio of acetoxystyrene to initiator is (30-300):1; in step (1), the added molar ratios of acetoxystyrene and trifluoromethyl potassium salt of styrenesulfonyl imide are n and z respectively, and the molar ratio of the added materials in step (2) satisfies intermediate I: first base = 1: (n-3n), the molar ratio of the added materials in step (3) satisfies intermediate II: second base: di-tert-butyl dicarbonate = 1: (0.05n-0.2n): (0.2-0.99n), and the molar ratio of the added materials in step (6) satisfies intermediate III: triphenylsulfonium bromide = 1: (z-2z).

5. The method for preparing the PAG-bonded photosensitive photoresist resin according to claim 3, characterized in that: The RAFT chain transfer agent described in step (1) is any one of 2-(((dodecylsulfanyl)thioacyl)-sulfanyl)propionic acid, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid, 4-cyano-4-(phenylcarbonylthio)pentanoic acid, 2-phenyl-2-propylbenzodisulfide, 2-cyano-2-propylbenzodisulfide, 2-cyano-2-propyldodecyltrithiocarbonate or 1-(methoxycarbonyl)benzodithioic acid ethyl ester.

6. The method for preparing the PAG-bonded photosensitive photoresist resin according to claim 3, characterized in that: The initiator described in step (1) is an azo free radical initiator or a peroxide free radical initiator, wherein the azo initiator is any one of azobisisobutyronitrile, azobisisoheptanenitrile or dimethyl azobisisobutyrate, and the peroxide free radical initiator is any one of dibenzoyl peroxide, tert-butyl hydroperoxide or benzoic acid hydroperoxide.

7. The method for preparing the PAG-bonded photosensitive photoresist resin according to claim 3, characterized in that: The first solvent is one or more of dichloromethane, chloroform, dioxane, tetrahydrofuran, N,N-dimethylformamide, propylene glycol methyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, ethyl acetate, ethylene glycol monomethyl ether acetate, acetone, cyclohexanone or methanol; the second solvent is water; the third solvent is any one of n-hexane, petroleum ether or cyclohexane; the first base is any one of sodium hydroxide, lithium hydroxide, potassium hydroxide or ammonia water; the second base is any one of 4-dimethylaminopyridine, lithium carbonate, calcium carbonate, sodium carbonate, potassium carbonate, potassium tert-butoxide or sodium methoxide; the acid used to adjust the pH of the reaction solution in step (2) is any one of hydrochloric acid, phosphoric acid, formic acid, acetic acid or aminoacetic acid.

8. The method for preparing the PAG-bonded photosensitive photoresist resin according to claim 3, characterized in that: The RAFT polymerization reaction temperature in step (1) is 40-100° C. and the time is 5-24 h; the hydrolysis reaction temperature in step (2) is 20-70° C. and the time is 2-24 h; the introduction of protective groups in step (3) is 20-60° C. and the time is 2-24 h; the ion exchange reaction temperature in step (6) is 20-60° C. and the time is 2-24 h.

9. A photoresist, characterized in that: The photoresist is formed by stirring and mixing the PAG-bonded photosensitive photoresist resin according to claim 1 and a solvent, wherein the mass fraction of the resin in the photoresist is 5%-30%; and 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.

10. A method for forming a photolithographic pattern, characterized in that: The photoresist as claimed in claim 9 is used, coated on a substrate to be photolithographically processed, pre-baked, a mask is covered on the photoresist, and exposed, post-baked and developed to obtain the photolithographic pattern.

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