A polymer for arf photoresist, a preparation method and a photoresist composition

Abstract

The present application relates to the technical field of photoresist, in particular to an ArF photoresist polymer, a preparation method thereof and a photoresist composition, the polymer has the following general formula: x, y, z, m are mass fractions of polymer repeating units respectively, x is selected from 20-30%, y is selected from 10-15%, z is selected from 25-44%, m is selected from 15-30%, the molecular weight of the polymer is selected from 2000-20000 Da, and the molecular weight dispersion coefficient is selected from 1.0-3.0. The preparation method is as follows: monomer A, monomer B, monomer C, monomer D and a free radical initiator are mixed and dissolved in an electronic grade reaction solvent to prepare a mixed solution, the polymer is prepared by controlling the reaction temperature and the reaction time, after the reaction is completed, the reaction system is added dropwise into a poor solvent to granulate the polymer. The photoresist composition prepared by using the polymer has high resolution, good line width uniformity and good etching resistance.

Description

Technical Field

[0001] This invention relates to a polymer for ArF photoresist, a method for preparing the polymer, and a photoresist composition, belonging to the field of photoresist technology. Background Technology

[0002] In recent years, due to the high degree of centralization in large-scale integrated circuits, electronic devices have increasingly higher requirements for photolithography processes, and the resolution of photoresists has developed from micrometers and submicrometers to nanometers. ArF immersion lithography has become an advanced photolithography process.

[0003] As semiconductor manufacturing processes continue to advance towards higher densities and smaller dimensions, the performance requirements for ArF lithography technology and corresponding photoresists are also constantly increasing. In particular, challenges arise in areas such as photoresist resolution, etching resistance, post-imaging defect control, and linewidth uniformity.

[0004] Currently, (meth)acrylic acid polymers are one of the main materials for ArF photoresists. The numerous aliphatic ring structures result in poor etching resistance, leading to defects and poor linewidth uniformity in the patterns formed after exposure and etching processes. Existing technology involves adding maleic anhydride monomers to the polymer, but this increases polymer brittleness and also leads to poor pattern stability.

[0005] To overcome the above-mentioned defects and improve the performance of photoresist compositions, it is necessary to design a polymer for ArF photoresist that combines high resolution, good linewidth uniformity, and good etching resistance. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a polymer for ArF photoresist, a preparation method thereof, and a photoresist composition. The photoresist composition formulated with this polymer has high resolution, good linewidth uniformity, and good etching resistance.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a polymer for ArF photoresist, wherein the polymer has the following general formula:

[0008] ;

[0009] x, y, z, and m are the mass fractions of the polymer repeating units, where x is selected from 20-30%, y from 10-15%, z from 25-44%, and m from 15-30%. The molecular weight of the polymer is selected from 2000-20000 Da, and the molecular weight dispersion coefficient is selected from 1.0-3.0.

[0010] Preferably, the molecular weight of the polymer is selected from 6000-10000 Da, and the molecular weight dispersion coefficient is selected from 1.0-1.8.

[0011] Preferably, in the polymer repeating unit, x is selected from 20-30%, y is selected from 10-15%, z is selected from 35-40%, and m is selected from 20-30%.

[0012] This invention also discloses a method for preparing an ArF photoresist polymer, the method comprising:

[0013] A mixed solution was prepared by mixing monomers A, B, C, and D with a free radical initiator and dissolving them in an electronic-grade reaction solvent. The polymer was prepared by controlling the reaction temperature and reaction time. After the reaction was completed, the reaction system was added dropwise to a poor solvent to granulate the polymer.

[0014] The monomer A is 2-methyl-2-adamantyl methacrylate, monomer B is 3,5-dihydroxy-1-adamantyl methacrylate, monomer C is 2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester, and monomer D is methyl 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate.

[0015] Furthermore, in terms of mass fraction, monomer A accounts for 20-30% of the total mass of monomers, monomer B accounts for 10-15% of the total mass of monomers, monomer C accounts for 25-44% of the total mass of monomers, and monomer D accounts for 15-30% of the total mass of monomers.

[0016] Furthermore, the free radical initiator is selected from any one of azobisisobutyronitrile, azobisisovalerate, and dimethyl azobisisobutyrate.

[0017] Furthermore, the electronic-grade reaction solvent is selected from any one of propylene glycol methyl ether, propylene glycol methyl ether acetate, methyl isobutyl ketone, and dipropylene glycol methyl ether.

[0018] Furthermore, the reaction temperature is 40-100℃, and the reaction time is 2-10 hours.

[0019] Furthermore, the unsuitable solvent is at least one of methanol, ethanol, and water.

[0020] The present invention also discloses a photoresist composition comprising a polymer, a photoacid generator, and an electronic-grade solvent, wherein the polymer is the ArF photoresist polymer described in the present invention, or the polymer is an ArF photoresist polymer prepared according to a method for preparing an ArF photoresist polymer described in the present invention.

[0021] The beneficial effects of this invention are:

[0022] (1) The polymer structure involved in this invention contains methyl 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate monomer (i.e. monomer D), which contains fluorine groups. Fluorine atoms have high electronegativity and small atomic radius, making the CF bond very strong and the polarization low, which significantly reduces the light absorption coefficient of the polymer, enhances the light transmittance, and greatly improves the resolution of the photoresist.

[0023] (2) The strong polarity and steric hindrance effect of the fluorinated groups (i.e. monomer D) in the polymer involved in this invention can play a certain role in restricting the diffusion of photoacids (photogenerated acids) or acidic substances generated after exposure, preventing acid from diffusing into unexposed areas and causing unnecessary reactions, and making the edges of the pattern smoother. At the same time, it can significantly reduce the line width inhomogeneity caused by the randomness of acid diffusion.

[0024] (3) The polymer structure involved in this invention has two acid-instable hydroxyl groups (i.e., monomer B), which enhances the hydrophilicity of the polymer and improves the solubility of the polymer in the developer, thereby improving the clarity of the pattern. At the same time, fluorine atoms have very low surface energy (i.e., monomer D), which can effectively reduce the surface tension of the photoresist film, thereby obtaining a smoother and defect-free photoresist film.

[0025] (4) The polymer structure involved in this invention has a large number of adamantane structures, which are stable cyclic aliphatic structures. It also introduces 2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester (monomer C) and 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate methyl ester monomer (i.e. monomer D). Its diester structure enhances the polarity of the polymer, thereby improving the stability and flexibility of the photoresist composition, greatly improving the corrosion resistance of the composition, improving the contrast of the photoresist, and resulting in higher resolution after imaging.

[0026] (5) The preparation method of the present invention is simple and convenient. Attached Figure Description

[0027] Figure 1 For polymer Polymer A 13 C-NMR spectrum;

[0028] Figure 2 A scanned image of composition 1;

[0029] Figure 3 A scanned image of composition 7;

[0030] Figure 4 This is a scanned image of composition 8. Detailed Implementation

[0031] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0033] A polymer for ArF photoresist, said polymer having the following general formula:

[0034] ;

[0035] x, y, z, and m are the mass fractions of the polymer repeating units, where x is selected from 20-30%, y from 10-15%, z from 25-44%, and m from 15-30%. The molecular weight of the polymer is selected from 2000-20000 Da, and the molecular weight dispersion coefficient is selected from 1.0-3.0.

[0036] Preferably, the molecular weight of the polymer is selected from 6000-10000 Da, and the molecular weight dispersion coefficient is selected from 1.0-1.8.

[0037] Preferably, in the polymer repeating unit, x is selected from 20-30%, y is selected from 10-15%, z is selected from 35-40%, and m is selected from 20-30%.

[0038] A method for preparing an ArF photoresist polymer, the method comprising:

[0039] A mixed solution was prepared by mixing monomers A, B, C, and D with a free radical initiator and dissolving them in an electronic-grade reaction solvent. The polymer was prepared by controlling the reaction temperature and reaction time. After the reaction was completed, the reaction system was added dropwise to a poor solvent to granulate the polymer.

[0040] The monomer A is 2-methyl-2-adamantyl methacrylate, monomer B is 3,5-dihydroxy-1-adamantyl methacrylate, monomer C is 2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester, and monomer D is methyl 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate; all of the above monomers are known compounds and can be purchased from the market.

[0041] Specifically, in terms of mass fraction, monomer A accounts for 20-30% of the total mass of monomers, monomer B accounts for 10-15% of the total mass of monomers, monomer C accounts for 25-44% of the total mass of monomers, and monomer D accounts for 15-30% of the total mass of monomers.

[0042] Specifically, the free radical initiator is selected from any one of azobisisobutyronitrile, azobisisovalerate, and dimethyl azobisisobutyrate. The amount of the free radical initiator is 1-20% of the total mass of the monomers (the sum of the masses of monomers A, B, C, and D).

[0043] Preferably, the free radical initiator is azobisisobutyronitrile (AIBN).

[0044] Preferably, the amount of the free radical initiator is 5-10% of the total mass of the monomer.

[0045] Specifically, the electronic-grade reaction solvent is selected from any one of propylene glycol methyl ether, propylene glycol methyl ether acetate, methyl isobutyl ketone, and dipropylene glycol methyl ether.

[0046] Preferably, the electronic-grade reaction solvent is propylene glycol methyl ether.

[0047] Specifically, the reaction temperature is 40-100℃ and the reaction time is 2-10 hours.

[0048] Preferably, the reaction temperature is 70-90℃ and the reaction time is 2-5 hours.

[0049] Specifically, the unsuitable solvent is at least one of methanol, ethanol, and water.

[0050] A photoresist composition comprising a polymer, a photoacid generator, and an electronic-grade solvent, wherein the polymer is the ArF photoresist polymer described in this invention.

[0051] In this embodiment of the invention, the photo-induced acid-producing agent is 4-tert-butylphenyl diphenylsulfonyl nonafluorobutane sulfonate, and the electronic-grade solvent is propylene glycol methyl ether.

[0052] I. Polymer Preparation

[0053] Example 1

[0054] A mixed solution was prepared by dissolving 5.0 g of monomer A (2-methyl-2-adamantyl methacrylate), 2.0 g of monomer B (3,5-dihydroxy-1-adamantyl methacrylate), 7.0 g of monomer C (2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester), 6.0 g of monomer D (2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate]methyl valerate), and 1.6 g of azobisisobutyronitrile in 180.0 g of electronic-grade dipropylene glycol methyl ether. The reaction temperature was raised to 80-90 °C and the reaction was maintained at this temperature for 5 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of methanol, precipitating a white solid. The solid was filtered and dried to obtain polymer Polymer A. 14.0g, yield 70%, Mw=8047Da, PDI=1.66 (ratio of monomers A, B, C, and D in the polymer: 25:10:35:30 (mass ratio)).

[0055] The MRI scan showed: 13 C-NMR (400 MHz, (CD3)2CO), δ=25.381 (methyl carbon signal peak in 2-methyl-2-adamantyl methacrylate), δ=67.488 (hydroxyl-linked carbon signal peak in 3,5-dihydroxy-1-adamantyl methacrylate), δ=126.294 (lactone carbonyl carbon signal peak in 2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester), δ=9.129 (methyl carbon signal peak in methyl 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate), as shown in the attached figure. Figure 1 As shown.

[0056] Example 2

[0057] 5.0 g of monomer A (2-methyl-2-adamantyl methacrylate), 2.0 g of monomer B (3,5-dihydroxy-1-adamantyl methacrylate), 7.0 g of monomer C (2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester), and 6.0 g of monomer D (2,2-difluoro-3-[(2-methyl-1-oxo-2- A mixed solution was prepared by dissolving methyl pentanoate (propyleneyl) and 1.6 g of azobisisobutyronitrile in 180.0 g of electronic grade dipropylene glycol methyl ether. This mixed solution was then pumped into 80.0 g of electronic grade dipropylene glycol methyl ether using a metering pump. The reaction temperature was raised to 60-70℃ and maintained for 8 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of methanol, resulting in the precipitation of a white solid. The solid was filtered and dried to obtain 14.4 g of polymer Polymer B, with a yield of 72%, Mw = 9731 Da, and PDI = 1.78 (the ratio of monomers A, B, C, and D in the polymer was 25:10:35:30 (mass ratio)).

[0058] Example 3

[0059] A mixed solution was prepared by dissolving 5.0 g of monomer A (2-methyl-2-adamantyl methacrylate), 2.0 g of monomer B (3,5-dihydroxy-1-adamantyl methacrylate), 7.0 g of monomer C (2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester), 6.0 g of monomer D (2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate]methyl valerate), and 1.0 g of azobisisovalerate in 200.0 g of electronic grade propylene glycol methyl ether. The reaction temperature was raised to 70-80 °C and the reaction was maintained at this temperature for 5 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of ethanol. A white solid precipitated out, which was filtered and dried to obtain polymer Polymer C. 14.2g, yield 71%, Mw=9527Da, PDI=1.77 (the ratio of monomers A, B, C, and D in the polymer is 25:10:35:30 (mass ratio)).

[0060] Example 4

[0061] A mixed solution was prepared by dissolving 6.0 g of monomer A (2-methyl-2-adamantyl methacrylate), 2.0 g of monomer B (3,5-dihydroxy-1-adamantyl methacrylate), 8.0 g of monomer C (2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl methacrylate), 4.0 g of monomer D (methyl 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate), and 1.6 g of dimethyl azobisisobutyrate in 200.0 g of electronic grade propylene glycol methyl ether acetate. The reaction temperature was raised to 70-80 °C and the reaction was maintained at this temperature for 2 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of ethanol. A white solid precipitated out, which was filtered and dried to obtain polymer Polymer D. 13.8g, yield 69%, Mw=8439Da, PDI=1.76 (the ratio of monomers A, B, C, and D in the polymer is 30:10:40:20 (mass ratio)).

[0062] Example 5

[0063] A mixed solution was prepared by dissolving 5.0 g of monomer A (2-methyl-2-adamantyl methacrylate), 2.0 g of monomer B (3,5-dihydroxy-1-adamantyl methacrylate), 7.0 g of monomer C (2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester), 6.0 g of monomer D (2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate]methyl valerate), and 3.2 g of azobisisobutyronitrile in 180.0 g of electronic grade propylene glycol methyl ether. The reaction temperature was raised to 80-90 °C and the reaction was maintained at this temperature for 6 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of ethanol. A white solid precipitated out, which was filtered and dried to obtain polymer Polymer E. 12.8g, yield 64%, Mw=4319Da, PDI=1.55 (the ratio of monomers A, B, C, and D in the polymer is 25:10:35:30 (mass ratio)).

[0064] Example 6

[0065] A mixed solution was prepared by dissolving 4.0 g of monomer A (2-methyl-2-adamantyl methacrylate), 3.0 g of monomer B (3,5-dihydroxy-1-adamantyl methacrylate), 7.0 g of monomer C (2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester), 4.0 g of monomer D (2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate]methyl valerate), and 2.0 g of azobisisobutyronitrile in 180.0 g of electronic grade methyl isobutyl ketone. The reaction temperature was raised to 70-80 °C and the reaction was maintained at this temperature for 6 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of ethanol. A white solid precipitated out, which was filtered and dried to obtain polymer Polymer F. 14.0g, yield 70%, Mw=6723Da, PDI=1.62 (the ratio of monomers A, B, C, and D in the polymer is 20:15:35:20 (mass ratio)).

[0066] Comparative Example 1

[0067] A mixed solution was prepared by dissolving 5.0 g of adamantyl methacrylate, 2.0 g of 3-hydroxy-1-adamantyl methacrylate, 7.0 g of 2-ethyl-2-adamantyl methacrylate, 6.0 g of maleic anhydride, and 1.6 g of azobisisobutyronitrile in 180.0 g of electronic grade dipropylene glycol methyl ether. The reaction temperature was raised to 80-90℃ and the reaction was maintained at this temperature for 5 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of methanol, resulting in the precipitation of a white solid. The solid was filtered and dried to obtain 14.6 g of polymer Polymer X, with a yield of 73%, Mw=8319Da, and PDI=1.67 (the ratio of the monomers in the polymer was: adamantyl methacrylate: 3-hydroxy-1-adamantyl methacrylate: 2-ethyl-2-adamantyl methacrylate: maleic anhydride = 25:10:35:30 (mass ratio)).

[0068] Comparative Example 2

[0069] A mixed solution was prepared by dissolving 5.0 g of 1-ethylcyclopentyl methacrylate, 2.0 g of 3-hydroxy-1-adamantyl methacrylate, 7.0 g of 2-ethyl-2-adamantyl methacrylate, 6.0 g of hexafluoroisopropyl methacrylate, and 1.6 g of azobisisobutyronitrile in 180.0 g of electronic grade dipropylene glycol methyl ether. The reaction temperature was raised to 80-90℃ and the reaction was maintained at this temperature for 5 hours. After the reaction was completed, the system was cooled to room temperature and slowly added dropwise to 1000.0 g of methanol, resulting in the precipitation of a white solid. The solid was filtered and dried to obtain 14.2 g of polymer Polymer Y, with a yield of 71%, Mw=7134Da, and PDI=1.64 (the ratio of each monomer in the polymer was: 1-ethylcyclopentyl methacrylate: 3-hydroxy-1-adamantyl methacrylate: 2-ethyl-2-adamantyl methacrylate: hexafluoroisopropyl methacrylate = 25:10:35:30 (mass ratio)).

[0070] II. Preparation of Photoresist Composition

[0071] The polymer prepared in the above examples was combined with a photoacid-generating agent (4-tert-butylphenyl diphenylsulfonyl nonafluorobutane sulfonate) and an electronic-grade solvent, propylene glycol methyl ether, to form a photoresist composition with a certain solid content. The formulation of the photoresist composition is shown in Table 1.

[0072] Table 1. Formulation of photoresist composition

[0073]

[0074] The structural formula of polymer Polymer X (Comparative Example 1) is as follows:

[0075] ;

[0076] The structural formula of polymer Polymer Y (Comparative Example 2) is as follows:

[0077] ;

[0078] III. Performance Testing of Photoresist Compositions

[0079] The photoresist composition was spin-coated onto a 6-inch silicon wafer at rotation speeds of 0 rpm / 10 s, 200 rpm / 2 s, 0 rpm / 2 s, and 1500 rpm / 30 s. After spin-coating, the wafer was baked at 90°C on a hot plate for 1 minute and then cooled on a cold plate.

[0080] 1. The n / k value of each composition was tested using a Woollam RC2 ellipsometry from the USA;

[0081] 2. Then the above composition is at 15 mJ / cm 2Under the given exposure energy dose, a photolithographic pattern was obtained, and the scanned image was tested.

[0082] 3. The photoresist was continued to be etched using oxygen reactive ion etching, and its etching resistance was tested.

[0083] Etching resistance: The relative etching rate of the sample was calculated. The specific test results are shown in Table 2 below.

[0084] Table 2 Performance test results of photoresist compositions

[0085]

[0086] As shown in Table 2, after using the photoresist polymers of the present invention (compositions 1-6), due to the presence of methyl 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate monomer in the polymer, the polarizability of the fluorinated groups is extremely low, significantly reducing the light absorption coefficient (k) of the photoresist. Compositions 1-6 have lower light absorption (k) and higher light refractive index (n). Similarly, composition 8 also contains fluorinated groups, thereby improving the resolution of the photoresist composition (see Table 2). Figure 1 , Figure 2 , Figure 3 In contrast, composition 7, prepared from polymer X in the comparative example, has no fluorine-containing groups, and its photoresist composition has a high light absorption rate (k) and a low light transmittance.

[0087] As can be seen from the relative etching rates, after using the photoresist polymers of the present invention (compositions 1-6), due to the presence of a large amount of adamantane aliphatic ring structures in the polymers and the introduction of monomers 2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester (monomer C) and 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate methyl ester (monomer D), their diester structure increases the polarity of the polymer, thereby improving the stability and flexibility of the photoresist composition, thus improving the etching resistance. The etching rate is significantly lower than that of compositions 7 and 8.

[0088] In summary, the photoresist polymer described in this invention can significantly improve the resolution and etching resistance of photoresist compositions.

[0089] Determination of photoresist cross-sectional morphology: The cross-sectional morphology was observed using a scanning electron microscope, and the test results are shown in [see figure]. Figures 1-2 ( Figure 2 This is a scanned image of composition 1. Figure 3 This is a scanned image of composition 7 (Comparative Example 1). Figure 4(Scanned image of composition 8 (Comparative Example 2)): As can be seen from the comparison images, after using the photoresist polymer of the present invention (composition 1), the pattern morphology is clear, the line width is uniform, and the line edges are smoother, significantly improving the resolution and stability of the photoresist development pattern; while the pattern morphology of composition 7 is rough and blurry, and the line edges are rough; composition 8, due to its fluorine-containing monomers being too compliant and lacking a diester structure to enhance its polarity, results in obvious distortion of the pattern line edges and insufficient stability. In comparison, the photoresist polymer of the present invention has good application prospects.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above compositions and the monomers in the comparative examples are all known compounds and can be purchased on the market.

[0091] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A polymer for ArF photoresist, characterized in that, The polymer has the following general formula: ； x, y, z, and m are the mass fractions of the polymer repeating units, where x is selected from 20-30%, y from 10-15%, z from 35-40%, and m from 20-30%. The molecular weight of the polymer is selected from 2000-20000 Da, and the molecular weight dispersion coefficient is selected from 1.0-3.

0.

2. The polymer for ArF photoresist according to claim 1, characterized in that, The molecular weight of the polymer is selected from 6000-10000 Da, and the molecular weight dispersion coefficient is selected from 1.0-1.

8.

3. A method for preparing an ArF photoresist polymer according to any one of claims 1-2, characterized in that, The preparation method is as follows: A mixed solution was prepared by mixing monomers A, B, C, and D with a free radical initiator and dissolving them in an electronic-grade reaction solvent. The polymer was prepared by controlling the reaction temperature and reaction time. After the reaction was completed, the reaction system was added dropwise to a poor solvent to granulate the polymer. The monomer A is 2-methyl-2-adamantyl methacrylate, monomer B is 3,5-dihydroxy-1-adamantyl methacrylate, monomer C is 2-methacrylate-2-[(hexahydro-5-oxo-2,6-methylfurano[3,2-b]furan-3-yl)oxy]-2-oxoethyl ester, and monomer D is methyl 2,2-difluoro-3-[(2-methyl-1-oxo-2-propenyl)oxy]valerate.

4. The method for preparing an ArF photoresist polymer according to claim 3, characterized in that, Based on mass fraction, monomer A accounts for 20-30% of the total monomer mass, monomer B accounts for 10-15% of the total monomer mass, monomer C accounts for 25-44% of the total monomer mass, and monomer D accounts for 15-30% of the total monomer mass.

5. The method for preparing an ArF photoresist polymer according to claim 3, characterized in that, The free radical initiator is selected from any one of azobisisobutyronitrile, azobisisovalerate, and dimethyl azobisisobutyrate.

6. The method for preparing an ArF photoresist polymer according to claim 3, characterized in that, The electronic-grade reaction solvent is selected from any one of propylene glycol methyl ether, propylene glycol methyl ether acetate, methyl isobutyl ketone, and dipropylene glycol methyl ether.

7. The method for preparing an ArF photoresist polymer according to claim 3, characterized in that, The reaction temperature is 40-100℃, and the reaction time is 2-10 hours.

8. The method for preparing an ArF photoresist polymer according to claim 3, characterized in that, The unsuitable solvent is at least one of methanol, ethanol, and water.

9. A photoresist composition, characterized in that, The photoresist composition comprises a polymer, a photoacid generator, and an electronic-grade solvent, wherein the polymer is the ArF photoresist polymer according to any one of claims 1-2, or the polymer is an ArF photoresist polymer prepared according to a method for preparing an ArF photoresist polymer according to any one of claims 3-8.

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