Iodonium salt polymer, preparation method thereof and application of iodonium salt polymer in photoetching

Abstract

The invention belongs to the technical field of photoetching, and particularly relates to iodonium salt polymer photoresist as shown in a formula (I) as well as a preparation method and application of the iodonium salt polymer photoresist. The photoresist material provided by the invention is simple in preparation method, controllable in polymerization molecular weight, good in thermal stability, free from precipitation in a baking process, easy to store and not easy to denature; the photoresist provided by the invention has good film-forming property, a uniform film with controllable film thickness can be obtained on a substrate through spin coating, the film can be used in modern photoetching technologies such as 254nm photoetching, 248nm photoetching, 193nm photoetching, extreme ultraviolet photoetching, electron beam photoetching and the like, and as a non-chemical amplification negative photoresist, good resolution and relatively low line edge roughness can be realized; and an exposed pattern has a relatively high contrast ratio. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of photoresists, and particularly relates to a class of iodonium salt polymers, a preparation method thereof, and an application thereof in lithography. Background Art

[0002] The semiconductor industry has achieved rapid development due to breakthroughs in integrated circuit technology, and the development of integrated circuits is inseparable from the progress of lithography technology. Lithography technology refers to a fine processing technology in which a photoresist undergoes a photochemical change under the action of light or an electron beam with a special wavelength, and the pattern designed on a mask is transferred to a substrate through processes such as coating, exposure, development, and etching. Therefore, photoresist is one of the core materials in the manufacture of large-scale integrated circuits.

[0003] The most important technical indicators of photoresist include resolution, photosensitivity (sensitivity), and line edge roughness. Resolution is the minimum feature size that can be successfully printed and determines the minimum feature size of a transistor. Sensitivity is the dose required for the photoresist to obtain the desired structure. Line edge roughness is an important parameter describing the roughness of line features.

[0004] The chemically amplified photoresist widely used in the current lithography field improves the efficiency of the photochemical reaction through a chain reaction and enhances the sensitivity of the photoresist. Chemically amplified photoresists usually consist of a film-forming resin (main material), a photoacid generator, a solvent inhibitor, and a solvent, etc. After exposure, the photoacid generated by the photoacid generator catalyzes the leaving of acid-sensitive groups in the main material to achieve the solubility transformation of the film-forming resin. However, the acid diffusion process will cause uneven distribution of the photoacid, which in turn causes a significant increase in line edge roughness, so it is impossible to achieve high-quality lithography patterns at higher resolutions. Existing work has bonded the photoacid generator to the polymer main chain to limit the diffusion of the photoacid, but in the face of the higher resolution requirements of integrated circuits, the design of photoresists needs to be more oriented to non-chemically amplified photoresists.

[0005] Non-chemically amplified photoresists combine the photosensitive part with the main material and achieve the solubility transformation through a chemical reaction after exposure. Therefore, other components such as photoacid generators and quenchers are not required, avoiding the problem of uneven distribution of components. Summary of the Invention

[0006] The purpose of the present invention is to provide a class of iodonium salt polymers and a preparation method thereof.

[0007] Another purpose of the present invention is to provide the application of the above-mentioned iodonium salt polymer as a photoresist in extreme ultraviolet lithography, deep ultraviolet lithography, and electron beam lithography.

[0008] The technical solution provided by the present invention is as follows:

[0009] A polymer represented by formula (I):

[0010]

[0011] Among them, X - is an acid anion selected from TsO - PF6 - 、SbF6 - 、BF4 - 、F - , Cl - Br - , C 1-8 Alkylsulfonic acid anion or C 1-8 Perfluoroalkylsulfonic acid anion;

[0012] R1 is selected from H, OH, C 1-8 Alkyl or C 1-8 Alkoxy;

[0013] n is 1, 2, 3, 4, or 5;

[0014] R2 is selected from -C 6-22 Aryl, -C 6-22 Aryl-C 1-8 Alkyl, -C 6-22 Aryl-CN, -C 6-22 Aryl-C 1-8 Alkoxy, 5-20 membered heteroaryl, -5-20 membered heteroaryl-C 1-8 Alkyl, -5-20 membered heteroaryl-C 1-8 Alkoxy;

[0015] x and y represent the molar percentages of the two repeating units in the polymer, x+y=1, 0.3<y≤1.

[0016] According to an embodiment of the present invention, X - Selected from C4F9SO3 - 、TsO - PF6 - 、SbF6 - 、BF4 - 、F - , Cl - Br - or TfO - ;

[0017] R1 is selected from H, OH, C 1-4 Alkyl or C 1-4 Alkoxy;

[0018] R2 is selected from C 6-14 Aryl, -C 6-14 Aryl-CN, -C 6-14 Aryl-C 1-4 Alkyl, -C 6-14 Aryl-C1-4 Alkoxy, 5- to 14-membered heteroaryl-C 1-4 Alkyl, -5- to 14-membered heteroaryl-C 1-4 Alkoxy;

[0019] According to an embodiment of the present invention, X - is selected from TfO - or C4F9SO3 - ;

[0020] R1 is selected from H, OH, C 1-3 Alkyl, C 1-3 Alkoxy;

[0021] R2 is selected from -phenyl-C 1-4 Alkyl, -phenyl-CN, phenyl, naphthyl, -phenyl-C 1-4 Alkoxy, -pyridyl-C 1-4 Alkyl or -pyridyl-C 1-4 Alkoxy;

[0022] According to an embodiment of the present invention, the -phenyl-C 1-4 Alkyl, -phenyl-CN, -phenyl-C 1-4 Alkoxy, -pyridyl-C 1-4 Alkyl or -pyridyl-C 1-4 In the alkoxy, the substitution sites of the substituents C 1-4 Alkyl, CN or C 1-4 Alkoxy are the same or different and are independently selected from the ortho, para or meta positions of the benzene ring or pyridine ring. For example, C 1-4 Alkyl and CN are substituted at the para position of the phenyl.

[0023] According to an embodiment of the present invention, the polymer represented by formula (I) is selected from the following structures:

[0024]

[0025]

[0026] wherein, x is 0.4; y is 0.6, or x is 0.5; y is 0.5; or x is 0.6; y is 0.4; or x is 0.45 and y is 0.55.

[0027] According to an embodiment of the present invention, the molecular weight of the polymer is 500 - 200,000 daltons, for example 1,000 - 100,000 daltons, and still for example 5,000 - 50,000 daltons.

[0028] The present invention also provides a method for preparing the polymer represented by formula (I), comprising the following steps:

[0029] The polymer (ii) reacts with the compound (iii) in the presence of HX to obtain the polymer shown in formula (I);

[0030]

[0031] wherein n, x, y, X, R1, and R2 independently of one another have the definitions described above.

[0032] According to an embodiment of the present invention, the method further includes the preparation process of the raw material polymer (ii), including the following steps:

[0033] The compound (i) undergoes a polymerization reaction to obtain the polymer (ii);

[0034]

[0035] wherein n, R1, x, and y have the definitions described above.

[0036] According to an embodiment of the present invention, the polymerization reaction carried out by the compound (i) is a controlled radical polymerization, which is carried out in the presence of a radical initiator, for example, in the presence of azobisisobutyronitrile.

[0037] According to an embodiment of the present invention, the polymerization reaction carried out by the compound (i) is carried out in the presence of a chain transfer agent, for example, in the presence of 2-[dodecylthio(thiocarbonyl)thio]-2-methylpropanoic acid.

[0038] According to an embodiment of the present invention, the polymerization reaction carried out by the compound (i) is carried out in an inert gas atmosphere, for example, in argon.

[0039] The present invention also provides a photoresist composition, which includes the polymer shown in formula (I).

[0040] According to an embodiment of the present invention, the photoresist composition is a negative photoresist composition.

[0041] According to an embodiment of the present invention, the photoresist composition includes the polymer shown in formula (I) and a photoresist solvent.

[0042] According to an embodiment of the present invention, the photoresist solvent is, for example, selected from ester solvents, amide solvents, sulfone solvents, halogenated alkane solvents, ketone solvents, ether solvents, nitrile solvents, and alcohol solvents. For example, the solvent is at least one of methanol, ethanol, isopropanol, acetonitrile, ethyl acetate, ethyl lactate, cyclopentanone, cyclohexanone, chloroform, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide.

[0043] According to an embodiment of the present invention, in the photoresist composition, the mass of the polymer represented by formula (I) accounts for 1%-30%, preferably 2%-20%, of the total mass of the photoresist composition.

[0044] The present invention also provides the application of the polymer represented by formula (I) or the photoresist composition in photolithography processes such as 254 nm photolithography, 248 nm photolithography, 193 nm photolithography, extreme ultraviolet (EUV) photolithography, or electron beam lithography (EBL).

[0045] The present invention also provides a photoresist coating, which comprises the polymer represented by formula (I) or the photoresist composition as described above.

[0046] The present invention also provides a method for preparing the photoresist coating, which includes coating (such as spin-coating) the photoresist composition on a substrate.

[0047] Preferably, the coating method is spin-coating on the substrate by a spin coater.

[0048] Preferably, the substrate can be a silicon wafer, a silicon dioxide wafer, or a compound semiconductor wafer.

[0049] Beneficial Effects

[0050] In the present invention, an iodonium salt is combined with the polymer main chain to obtain a photoresist material with good thermal stability, controllable molecular weight and properties, and the synthesis method is simple.

[0051] The polymer material provided by the present invention can be used as a non-chemically amplified negative photoresist. This polymer material has a relatively high melting point and glass transition temperature, remains stable during high-temperature baking, and can meet the requirements of photolithography technology.

[0052] The material provided by the present invention has good stability, is convenient for storage, can be dissolved in common organic solvents, and has good film-forming properties. The pattern obtained by exposure has excellent resolution and photosensitivity, and no post-baking step is required during the pattern preparation process.

[0053] The photoresist of the present invention has a benzene ring-containing main chain, a high carbon-hydrogen ratio, and high etching resistance, and can be used for further pattern transfer.

[0054] The photoresist of the present invention can be used to prepare a uniform thin film. The thin film has good adhesion (film-forming property), low surface roughness of the thin film, and low viscosity, and no additional solvent dilution or treatment is required during use. After electron beam exposure and development, the exposed pattern has a high contrast, ultra-high resolution, can reach a feature size of 16 nm, and has excellent etching resistance at the same time. Description of the Drawings

[0055] Figure 1 It is the TGA curve of polymer (C).

[0056] Figure 2 It is the electron microscope photograph of the electron beam exposure pattern in Example 8.

[0057] Figure 3 It is the electron microscope photograph of the 254 nm deep ultraviolet exposure pattern in Example 9.

[0058] Figure 4 It is the electron microscope photograph of the silicon wafer after etching in Example 10.

[0059] Term Definitions and Explanations

[0060] Unless otherwise defined, all scientific and technical terms used herein have the same meanings as those commonly understood by those skilled in the art to which the claimed subject matter pertains.

[0061] The term "C 1-8 alkyl" should be understood to mean a straight-chain or branched-chain saturated monovalent hydrocarbon group having 1 to 8 carbon atoms. The alkyl groups are, for example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl, etc. or their isomers.

[0062] The term "C 6-22 aryl" should be understood to preferably mean a monocyclic, bicyclic (such as fused, bridged, spiro) or tricyclic hydrocarbon ring having 6 to 22 carbon atoms, which is monocyclic aromatic or partially aromatic, and which may be a mononuclear aromatic ring or a polynuclear aromatic ring fused together, preferably "C 6-14 aryl". The term "C 6-14 aryl" should be understood to preferably mean a monocyclic, bicyclic or tricyclic hydrocarbon ring having 6, 7, 8, 9, 10, 11, 12, 13 or 14 carbon atoms, which is monocyclic aromatic or partially aromatic ("C 6-14 aryl"), especially a ring having 6 carbon atoms ("C6 aryl"), such as phenyl; or biphenyl, or a ring having 9 carbon atoms ("C9 aryl"), such as indanyl or indenyl, or a ring having 10 carbon atoms ("C 10 aryl"), such as tetrahydronaphthyl, dihydronaphthyl or naphthyl, or a ring having 13 carbon atoms ("C 13 aryl"), such as fluorenyl, or a ring having 14 carbon atoms ("C 14"Aryl"), such as anthryl, or a ring having 16 carbon atoms ("C 16 "Aryl"), such as pyrenyl. When the C 6-22 group is substituted, it can be mono-substituted or multi-substituted. Moreover, there is no restriction on the substitution site, for example, it can be ortho-substituted, para-substituted or meta-substituted.

[0063] The term "5-20 membered heteroaryl" should be understood to include such monovalent monocyclic, bicyclic or tricyclic aromatic ring systems: having 5 to 20 ring atoms and containing 1-5 heteroatoms independently selected from N, O and S, such as "5-14 membered heteroaryl". The term "5-14 membered heteroaryl" should be understood to include such monovalent monocyclic, bicyclic or tricyclic aromatic ring systems: having 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 ring atoms, especially 5 or 6 or 9 or 10 carbon atoms, and containing 1-5, preferably 1-3 heteroatoms independently selected from N, O and S, and, additionally, can be benzo-fused in each case. In particular, heteroaryl is selected from thienyl, furyl, pyrrolyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, triazolyl, thiadiazolyl, thia-4H-pyrazolyl, etc. and their benzo derivatives, such as benzofuryl, benzothienyl, benzoxazolyl, benzisoxazolyl, benzimidazolyl, benzotriazolyl, indazolyl, indolyl, isoindolyl, etc.; or pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, etc., and their benzo derivatives, such as quinolinyl, quinazolinyl, isoquinolinyl, etc.; or azocinyl, indolizinyl, purinyl, etc. and their benzo derivatives; or cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, naphthyridinyl, pteridinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, etc.

[0064] The above definition of the term "C 1-8 alkyl" also applies to other terms containing "C 1-8 alkyl", such as the term "C 1-8 alkoxy", "C 1-8 perfluoroalkyl", and so on. Detailed Description of Specific Embodiments

[0065] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only for illustrative explanation of the present invention and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0066] Unless otherwise specified, the raw materials and reagents used in the following embodiments are commercially available products or can be prepared by known methods.

[0067] Example 1: Preparation of Compound (C)

[0068]

[0069]

[0070] Weigh 10.42 g (0.1 mol) of styrene, 729.36 mg (2 mmol) of 2-(dodecyltrithiocarbonate)-2-methylpropanoic acid (MDFC), and 164.21 mg (1 mmol) of azobisisobutyronitrile (AIBN). Add the above raw materials into a 100 ml two-necked flask. The two-necked flask is evacuated and filled with nitrogen three times repeatedly. Measure 20 ml of THF and add it to the two-necked flask. After stirring and dissolving, heat it up to 70 °C and stir for 12 h. After the reaction is completed, drop the reaction solution into methanol for precipitation. After filtration and drying, the polymer (C-1) is obtained. 1 1H NMR (300 MHz, CDCl3) δ 6.81 (dd, J = 157.1, 19.6 Hz, 5H), 2.41–0.86 (m, 4H). The weight-average molecular weight was measured by GPC to be approximately 4710 daltons.

[0071] Dissolve 5.14 g of the polymer (C-1) in 25 ml of THF. After stirring and dissolving, heat it up to 60 °C, add 2.5 ml of n-hexylamine dropwise. After reacting for 30 min, drop the reaction solution into methanol for precipitation to obtain the decolorized polymer (C-1).

[0072] Weigh 5.225 g of the decolorized polymer (C-1) and 12.33 g of m-chloroperoxybenzoic acid (m-CPBA). Add the above raw materials into a 100 ml three-necked flask. Evacuate and fill with nitrogen three times repeatedly, then add 16.9 g of p-tert-butyl iodobenzene. Measure 50 ml of dichloromethane and add it to the three-necked flask. After stirring and dissolving, place it in an ice-water bath, add 9.75 g of trifluoromethanesulfonic acid (TfOH) dropwise, and react for 1 h in the ice-water bath. After the reaction is completed, drop the reaction solution into ether for precipitation. After filtration and drying, the polymer (C) is obtained. 1 1H NMR (400 MHz, DMSO-d6) δ 8.36–5.85 (m, 1H), 1.10 (dd, J = 36.1, 29.1 Hz, 1H), 1.10 (dd, J = 36.1, 29.1 Hz, 1H). By 1 1H NMR measurement, the molar content x is 0.4 and y is 0.6.

[0073] The TGA curve of the obtained polymer (C) is as Figure 1 shown. It can be seen from Figure 1 that the polymer (C) remains stable within 200 °C and has high thermal stability.

[0074] Example 2

[0075] Prepare polymer (2), and the synthetic route is as follows:

[0076]

[0077] Specific steps: Add the polystyrene prepared in Example 1 into a 100 ml round-bottom flask, and then add the solvent DCM (50 ml), iodobenzene (0.5 eq) and m-CPBA (0.65 eq). Dropwise add perfluoro-1-butanesulfonic acid (0.65 eq) under the condition of 0 °C. Stir overnight in an ice bath. After dissolving the product in acetonitrile, drop it into diethyl ether for precipitation to obtain the final product. After confirmation by NMR, the molar contents of x is 0.5 and y is 0.5, and then dry it under vacuum. 1 H NMR (400 MHz, deuterated acetonitrile) δ (ppm) 8.13 (s, 1H), 7.95 (s, 1H), 7.50 (s, 1.5H), 7.37 (s, 1H), 6.55 (s, 2.5H), 1.2 - 1.8 (s, 3H).

[0078] Example 3

[0079] Prepare polymer (3), and the synthetic route is as follows:

[0080]

[0081] Specific steps: Add the polystyrene prepared in Example 1 into a 100 ml round-bottom flask, and then add the solvent DCM (50 ml), 4-iodobenzonitrile (0.5 eq) and m-CPBA (0.65 eq). Dropwise add perfluoro-1-butanesulfonic acid (0.65 eq) under the condition of 0 °C. Naturally restore to room temperature and stir overnight. After dissolving the product in acetonitrile, drop it into diethyl ether for precipitation to obtain the final product. After confirmation by NMR, the molar contents of x is 0.5 and y is 0.5, and then dry it under vacuum. 1 H NMR (400 MHz, deuterated acetonitrile) δ (ppm) 8.35 (s, 1H), 8.15 (s, 1H), 7.99 (s, 1H), 7.52 (s, 1H), 6.58 (s, 2.5H), 1.2 - 1.8 (s, 3H).

[0082] Example 4

[0083] Prepare polymer (4), and the synthetic route is as follows:

[0084]

[0085] Specific steps: Add the polystyrene prepared in Example 1 into a 100 ml round-bottom flask, then add the solvent DCM (50 ml), 2-iodonaphthalene (0.5 eq) and m-CPBA (0.65 eq). Dropwise add perfluoro-1-butanesulfonic acid (0.65 eq) under the condition of 0 °C. Naturally restore to room temperature and stir overnight. After dissolving the product in acetonitrile, drop it into ether for precipitation to obtain the final product. The molar contents x is 0.6 and y is 0.4 as confirmed by NMR, and then dry it under vacuum. 1 H NMR (400 MHz, deuterated acetonitrile) δ (ppm) 8.89 (s, 0.5H), 8.27 (s, 1H), 7.97 (s, 3H), 7.51 (s, 1H), 7.38 (s, 0.5H), 6.55 (s, 2H), 1.2 - 1.8 (s, 3H).

[0086] Example 5: A photoresist composition containing polymer (D)

[0087] Polymer D:

[0088] Weigh 40 mg of polymer (D), measure 2 ml of the photoresist solvent ethyl lactate, and prepare a photoresist solution with a concentration of 20 mg / mL. After ultrasonic treatment for 30 min, filter it three times with a 0.20 μm polytetrafluoroethylene membrane to prepare a negative photoresist composition.

[0089] Among them, polymer D is prepared by a method similar to that of Example 1. 1 H NMR (400 MHz, DMSO) δ 7.64 (dd, J = 363.3, 67.8 Hz, 1H), 2.30 (d, J = 35.7 Hz, 1H), 1.17 (d, J = 57.9 Hz, 1H). After 1 H NMR test, where the molar contents x is 0.45 and y is 0.55.

[0090] Example 6: A photoresist composition containing polymer (E)

[0091] Polymer E:

[0092] Weigh 40 mg of polymer (E), measure 2 ml of the photoresist solvent acetonitrile, and prepare a photoresist solution with a concentration of 20 mg / mL. After ultrasonic treatment for 30 min, filter it three times with a 0.20 μm polytetrafluoroethylene membrane to prepare a negative photoresist composition.

[0093] Among them, polymer E is prepared by a method similar to that of Example 1. 11H NMR (400 MHz, DMSO) δ 7.64 (dd, J = 363.3, 67.8 Hz, 4H), 2.30 (d, J = 35.7 Hz, 1H), 1.17 (d, J = 57.9 Hz, 1H). After 1 1H NMR test, where the molar content x is 0.5 and y is 0.5.

[0094] Example 7: Photoresist Composition Containing Polymer (C)

[0095] Weigh 40 mg of polymer (C) and measure 2 ml of cyclohexanone, a photoresist solvent, to prepare a photoresist solution with a concentration of 20 mg / mL. After ultrasonic treatment for 30 min, filter it three times with a 0.20 μm polytetrafluoroethylene membrane to prepare a negative photoresist composition.

[0096] Example 8: Electron Beam Lithography Performance of Negative Photoresist Composition Containing Polymer (C)

[0097] Select an untreated blank silicon wafer, blow the dust on the surface with a nitrogen gun, spin-coat the negative photoresist composition prepared in Example 7 on the silicon wafer, set the spin-coating parameters as 2500 rpm / 90 s, and the pre-baking parameters as 100 °C / 180 s. Measure the film thickness with an optical ellipsometer, which is 33 nm. Expose it with an electron beam with an acceleration voltage of 100 kV, and then develop it with a developer with V 甲基异丁基甲酮：乙醇 = 1:7 for 60 s and rinse it with ethanol for 60 s. After development, use a Hitachi 8230 scanning electron microscope to collect SEM images. The specific lithography results are as Figure 2 shown. It can be seen from Figure 2 that the photoresist composition can achieve a 16 nm lithography stripe and a relatively high contrast.

[0098] Example 9: Deep Ultraviolet Lithography Performance of Negative Photoresist Composition Containing Polymer (C)

[0099] Basically referring to Example 8, replace the electron beam exposure with 254 nm mercury lamp source exposure, and then develop it with a developer with V 甲基异丁基甲酮：乙醇 = 1:7 for 60 s and rinse it with ethanol for 60 s. After development, use a Hitachi 8230 scanning electron microscope to collect SEM images. The specific lithography results are as Figure 3 shown. It can be seen from Figure 3 that the photoresist composition can achieve micron-scale lithography stripes (stripe width is 1 μm) under deep ultraviolet conditions and a relatively high contrast.

[0100] Example 10: Etching Resistance Performance of Negative Photoresist Composition Containing Polymer (C)

[0101] The silicon wafer after photolithography and development in Example 8 was etched in an SF6 / O2 atmosphere to obtain a silicon wafer cross-section with an etch ratio of 11.7:1. The specific etching results are as Figure 4 shown. It is proved that the obtained photoresist composition has high etching resistance and a higher etch ratio compared with the silicon wafer.

[0102] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A polymer represented by formula (I): Among them, X - is an anionic acid radical and is selected from TsO - , PF6 - , SbF6 - , BF4 - , F - , Cl - , Br - , C 1-8 alkylsulfonic acid anion or C 1-8 perfluoroalkylsulfonic acid anion; R1 is selected from H, OH, C 1-8 alkyl or C 1-8 alkoxy; n is 1, 2, 3, 4, or 5; R2 is selected from -C 6-22 aryl, -C 6-22 aryl-C 1-8 alkyl, -C 6-22 aryl-CN, -C 6-22 aryl-C 1-8 alkoxy, 5-20 membered heteroaryl, -5-20 membered heteroaryl-C 1-8 alkyl, -5-20 membered heteroaryl-C 1-8 alkoxy; x and y represent the molar percentages of the two repeating units in the polymer, x+y=1, 0.3<y≤1.

2. The polymer according to claim 1, characterized in that X - Selected from C4F9SO3 - 、TsO - PF6 - 、SbF6 - 、BF4 - 、F - 、Cl - Br - or TfO - ; R1 is selected from H, OH, C 1-4 alkyl or C 1-4 alkoxy; R2 is selected from C 6-14 Aryl, -C 6-14 Aryl-CN, -C 6-14 Aryl-C 1-4 Alkyl, -C 6-14 Aryl-C 1-4 Alkoxy, 5-14 membered heteroaryl-C 1-4 Alkyl, -5-14 membered heteroaryl-C 1-4 Alkoxy.

3. The polymer according to claim 1 or 2, characterized in that, X - Selected from TfO - or C4F9SO3 - ; R1 is selected from H, OH, C 1-3 alkyl, C 1-3 alkoxy; R2 is selected from -phenyl-C 1-4 alkyl, -phenyl-CN, phenyl, naphthyl, -phenyl-C 1-4 alkoxy, -pyridyl-C 1-4 alkyl or -pyridyl-C 1-4 alkoxy.

4. The polymer according to any one of claims 1 to 3, characterized in that Said - phenyl - C 1-4 alkyl, - phenyl - CN, - phenyl - C 1-4 alkoxy, - pyridyl - C 1-4 alkyl or - pyridyl - C 1-4 The substitution site of the substituent C in alkoxy 1-4 alkyl, CN or C 1-4 alkoxy are the same or different, and are independently selected from the ortho, para or meta positions of the benzene ring or pyridine ring respectively.

5. The polymer according to any one of claims 1 to 4, characterized in that The polymer represented by formula (I) is selected from the following structures: Among them, x is 0.4; y is 0.6, or x is 0.5; y is 0.5; or x is 0.6; y is 0.4; or x is 0.45, y is 0.

55.

6. The method for preparing the polymer according to any one of claims 1 to 5, characterized in that: The following steps are involved: The polymer (ii) reacts with the compound (iii) in the presence of HX to obtain a polymer represented by formula (I); wherein n, x, y, X, R1, and R2 independently have the definitions described in any one of claims 1 to 5.

7. A photoresist composition comprising the polymer according to any one of claims 1 to 5.

8. The photoresist composition according to claim 7, wherein The photoresist composition is a negative photoresist composition; Preferably, in the photoresist composition, the mass of the polymer represented by formula (I) accounts for 1% to 30% of the total mass of the photoresist composition.

9. Use of the polymer according to any one of claims 1 to 5 or the photoresist composition according to claim 7 or 8 in 254 nm lithography, 248 nm lithography, 193 nm lithography, extreme ultraviolet (EUV) lithography or electron beam lithography (EBL).

10. A photoresist coating comprising the polymer represented by formula (I) according to any one of claims 1 to 5 and the photoresist composition according to claim 7 or 8.

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