Onium salt compound, photoacid generator, photoresist composition, and pattern forming method

Abstract

The application discloses an onium salt compound, a photoacid generator, a photoresist composition and a pattern forming method, and relates to the field of photoresists. 20 The onium salt compound has a specific structural general formula: wherein R1, R2, R3 and R4 are independently a heteroatom-substituted or unsubstituted C1-C The onium salt compound of the structural general formula is completely soluble and uniformly dispersed in an organic solvent, and can ensure the uniformity of the composition when used as a resist composition. When the onium salt compound of the application is used as a photoacid generator in a resist composition, the large steric hindering group can effectively reduce the acid diffusion length, improve the LWR performance of a photoetching pattern, and the acetal and ester group structures in the onium salt compound can easily decompose the onium salt compound, and can maximally reduce the influence on the environment.

Description

Technical Field

[0001] This invention relates to the field of photoresist, and more specifically, to an onium salt compound, a photoacid generator, a photoresist composition, and a patterning method. Background Technology

[0002] Immersion lithography is an advanced lithography technique that increases the numerical aperture (NA) of a system by filling the space between a projection lens and a silicon wafer with a liquid, thereby improving resolution and expanding lithography process nodes. This technique primarily utilizes a 193nm wavelength ArF light source, filling the space between the lower surface of the last lens of the projection lens and the silicon wafer with a liquid (typically ultrapure water with a refractive index of 1.44) to achieve higher numerical aperture and exposure resolution.

[0003] However, with the continuous miniaturization of photolithography technology, the diffusion length of the photoacid generator in the photoresist is becoming increasingly close to the size of the formed pattern, making it increasingly difficult to form high-resolution patterns on the photoresist. Furthermore, the higher the resolution, the more significantly the line width roughness (LWR) of the photoresist pattern is affected by acid diffusion. Uneven distribution of the photoacid generator (PAG) in the resist film also adversely affects the line width roughness. The structure of the PAG anion profoundly influences the diffusion characteristics of the photoacid by affecting the interaction between the photoacid generator and other photoresist components. Therefore, it is necessary to design a PAG anion structure with excellent performance to further meet the requirements of low LWR and superior photolithography performance. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems and provide an onium salt compound, a photoacid generator, a photoresist composition, and a pattern forming method, which can significantly improve the LWR performance of the photoresist composition, thereby forming a high-resolution pattern.

[0005] The first aspect of this invention provides an onium salt compound with the following general structural formula:

[0006]

[0007] Among them, R1, R2, R3, and R4 are each independently heteroatom-substituted or unsubstituted C1 to C2 atoms. 20 One or more combinations of aliphatic chain hydrocarbon groups or cycloalkane groups;

[0008] Cation Z + Including thionium salt cations;

[0009] Furthermore, each of R1, R2, R3, and R4 independently comprises one or more combinations of methyl, cyclopentyl, and cyclohexyl groups;

[0010] Preferably, R1, R2, R3, and R4 are each independently one of cyclopentyl alkyl and cyclohexyl alkyl or a combination of both;

[0011] Further preferably, R1, R2, R3, and R4 are all cyclohexyl groups;

[0012] Furthermore, the onium salt compound comprises one or a combination of the following compounds:

[0013]

[0014] The preferred onium salt compound is:

[0015]

[0016] A second aspect of the present invention provides a photoacid generator containing the onium salt compound provided in the first aspect of the present invention.

[0017] A third aspect of the present invention provides an anti-corrosion composition comprising a photoacid generator, a quencher, a matrix resin, a fluorinated resin, and a solvent, as provided in the second aspect of the present invention.

[0018] The quenching agent comprises one or more combinations of ionic organic compounds or amine compounds, and the matrix resin is a polyacrylate derivative.

[0019] Furthermore, the cation of the ionic quencher is one or more combinations of the following structures:

[0020]

[0021]

[0022] The preferred cation of the ionic quencher is:

[0023]

[0024] The anion of the ionic quencher is one or more combinations of the following structures:

[0025]

[0026] The preferred anion of the ionic quencher is:

[0027]

[0028] The anion of the ionic quencher is further preferably:

[0029]

[0030] The amine-type quencher comprises one or more combinations of the following structures:

[0031]

[0032] The preferred amine quencher is:

[0033]

[0034] A further preferred amine quencher is:

[0035]

[0036] The quenching agent includes a combination of ionic quenching agents and amine quenching agents. Preferred quenching agent combinations are triphenylthiocamphor sulfonate and tri-n-pentylamine, triphenylthiocamphor sulfonate and tri-n-octylamine, and more preferred quenching agent combinations are triphenylthiocamphor sulfonate and tri-n-pentylamine.

[0037] Furthermore, the matrix resin is a ternary copolymer resin, and its repeating unit is:

[0038]

[0039] Where R A Each is an independent hydrogen atom or a methyl group; X1 and X2 are independent acid-unstable groups; Y is a polar group containing one or more combinations of cyano, carbonyl, carboxyl, ether bond, ester bond, sulfonate bond, carbonate bond, lactone ring, sulcinolone ring, and carboxylic anhydride.

[0040] Furthermore, each of the acid-unstable groups X1 and X2 independently comprises one or more combinations of the following structures:

[0041]

[0042] The preferred acid-unstable groups X1 and X2 are respectively:

[0043]

[0044] The Y group is one or more combinations of the following structures:

[0045]

[0046] The preferred Y group is:

[0047]

[0048] Furthermore, the photoacid generator (A), quencher (B), matrix resin (C), and fluorinated resin (D) of the resist composition are respectively:

[0049]

[0050] The solvent (E) is a mixed solution of propylene glycol monomethyl ether acetate, γ-butyrolactone and cyclohexanone.

[0051] A fourth aspect of the present invention provides a pattern forming method, comprising the following steps:

[0052] S1, Film formation: The photoresist composition described in the third aspect of the present invention is coated on a substrate and the photoresist composition described in the third aspect of the present invention is cured to form a photoresist film.

[0053] S2, Immersion Exposure: Light of a specific wavelength is transmitted through a liquid medium and then irradiated onto a specific area of ​​the photoresist film for exposure.

[0054] S3, Development: The photoresist film is treated with an alkaline aqueous solution.

[0055] Beneficial effects:

[0056] (1) The present invention provides a novel onium salt compound that is completely soluble and uniformly dispersed in organic solvents. Moreover, the acetal and ester structure in the onium salt compound makes it easy to decompose, thereby minimizing its impact on the environment.

[0057] (2) When the onium salt compounds of the present invention are used as photoacid generators in the resist composition, the uniformity of the composition can be guaranteed. Their large steric groups can effectively reduce the acid diffusion length and improve the LWR performance of the photolithographic pattern. Detailed Implementation

[0058] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the examples are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without a specified manufacturer are all commercially available conventional products. Furthermore, unless otherwise specified, "parts" in the embodiments of this application represent parts by mass.

[0059] The onium salt compounds, photoacid generators, and corrosion inhibitor compositions of the present invention will be described in detail below.

[0060] <Onium salts>

[0061] The first aspect of this invention provides an onium salt compound with the following general structural formula:

[0062]

[0063] Among them, R1, R2, R3, and R4 are each independently heteroatom-substituted or unsubstituted C1 to C2 atoms. 20 One or more combinations of aliphatic chain hydrocarbon groups or cycloalkane groups; Z + Including thionium salt cations.

[0064] In this invention, onionium salt compounds can generate acids upon light exposure. These acids cause deprotection reactions in polymers such as matrix resins, thereby altering the solubility of the polymers. After development, specific patterns can be formed on the polymers such as matrix resins coated with the aforementioned onionium salt compounds.

[0065] In this invention, when the adamantane groups and lactone, acetal, or similar groups in the anionic moiety of onium salt compounds are linked together, a rigid molecular structure is formed, restricting their movement. Simultaneously, the hydrogen bonding interaction between these sterically hindered groups and photoacids can further effectively control the acid diffusion length, improving the LWR performance of the photolithographic pattern. Furthermore, the ester and acetal groups are easily decomposed, allowing the onium salt compounds to be degraded after use, minimizing their environmental impact.

[0066] In the cyclic acetal moiety, the R1, R2, R3, and R4 groups generally play an auxiliary role in regulating steric hindrance. Each group can be independently heteroatom-substituted or unsubstituted C1-C1. 20 One or more combinations of aliphatic chain hydrocarbon groups or cycloalkane groups.

[0067] C1~C 20 The aliphatic hydrocarbon group can be one or more combinations of straight-chain, branched, or cyclic structures, and examples include alkyl groups such as methyl, isopropyl, sec-butyl, tert-butyl, tert-pentyl, n-pentyl, n-hexyl, n-octyl, n-nonyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, cyclopentylmethyl, cyclopentylethyl, cyclopentylbutyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylbutyl, norbornyl, adamantyl, and adamantylmethyl. Compared to straight-chain aliphatic hydrocarbon groups with the same number of carbon atoms, branched or cyclic aliphatic hydrocarbon groups have greater steric hindrance, thereby reducing the acid diffusion length of onium salts and facilitating better control of the acid diffusion length. Therefore, one or more combinations of branched or cyclic aliphatic hydrocarbon groups are preferred. More specifically, it can be one or a combination of cyclopentyl, cyclohexyl, and other aliphatic hydrocarbon groups. Further preferred are R1, R2, R3, and R4, all of which are cyclohexyl. Additionally, C1 to C4... 20 Some hydrogen atoms in aliphatic hydrocarbon groups can be replaced by groups containing heteroatoms such as oxygen, sulfur, nitrogen, and halogen atoms, or groups containing heteroatoms such as oxygen, sulfur, and nitrogen atoms can exist between carbon atoms, forming C1-C groups containing heteroatoms. 20Aliphatic hydrocarbon group, containing heteroatoms C1 to C 20 Aliphatic hydrocarbon groups may contain one or more combinations of hydroxyl, cyano, carbonyl, ether, thioether, ester, sulfonate, carbonate, carbamate, lactone ring, etc.

[0068] Due to the presence of sterically hindered groups, their solubility is generally poor, and they exhibit a high degree of stacking, making it difficult to completely dissolve and uniformly disperse in organic solvents. Therefore, in this invention, the sterically hindered adamantyl alkyl groups and ester groups will react with SO3 through fluorine-containing groups. - This connection allows onium salts to become completely soluble and uniformly dispersed in organic solvents.

[0069] For ease of understanding, the anion of the present invention is given the following specific structural formula as an example:

[0070]

[0071] Preferred options are:

[0072]

[0073] Further preferred options are:

[0074]

[0075] The cation of this invention is an unsubstituted or substituted derivative of a triphenylthionium salt, wherein the substituent comprises one or more combinations of alkyl, alkoxy, hydroxyl, and fluorine-containing groups, thereby ensuring that the cationic moiety maintains a balance between solubility and photosensitivity. For ease of understanding, a specific structural formula of the cation is provided as an example:

[0076]

[0077] Preferred options are:

[0078]

[0079] In this invention, the onium salt compound comprises one or a combination of the following compounds:

[0080]

[0081] The preferred onium salt compound is:

[0082]

[0083] Of course, the specific embodiments of the present invention also provide a specific method for preparing the above-mentioned onium salt compounds, and the specific synthetic route is as follows:

[0084]

[0085] To obtain onium salt compounds with different substituents, it is only necessary to change the substituents based on the starting materials. Therefore, the synthesis method of each onium salt compound will not be described in detail here.

[0086] <Photoacid generator>

[0087] A second aspect of the present invention provides a photoacid generator, the components of which include the onium salt compounds described in the first aspect of the present invention.

[0088] Photoacid generators produce acid under light irradiation, causing denaturation of the matrix resin and altering its solubility. The photoacid generator of this invention exhibits a shorter acid diffusion length under light irradiation, effectively controlling this length and thus improving the LWR performance of the photolithographic pattern, resulting in a pattern with higher resolution.

[0089] <Corrosion Resistance Composition>

[0090] A third aspect of the present invention provides an anti-corrosion composition comprising the photoacid generator, quencher, matrix resin, fluorinated resin, and solvent described in the second aspect of the present invention.

[0091] Quenching agent

[0092] The anti-etching composition of the present invention includes a quencher, said quencher comprising one or more combinations of ionic organic compounds or amine compounds.

[0093] In resist compositions, quenchers can capture excess acid compounds generated by PAG and prevent other areas of the matrix resin from deteriorating. Therefore, quenchers are generally chosen as weakly acidic ionic organic compounds.

[0094] The cation of an ionic quencher is one or more combinations of the following structures:

[0095]

[0096] The preferred cation of the ionic quencher is:

[0097]

[0098] The anion of an ionic quencher is one or more combinations of the following structures:

[0099]

[0100] The preferred anion of the ionic quencher is:

[0101]

[0102] The anion of the ionic quencher is further preferably:

[0103]

[0104] Any one of the aforementioned cations and any one of the aforementioned anions can combine to form a complete quencher. Ionic quenchers function as quenchers in unexposed areas, while in exposed areas they neutralize the acid they generate themselves, losing their quencher function and further enhancing the contrast between exposed and unexposed areas.

[0105] In this invention, the amine quencher comprises one or more combinations of the following structures:

[0106]

[0107] The preferred amine quencher is:

[0108]

[0109] A further preferred amine quencher is:

[0110]

[0111] In this invention, ionic quenchers can be used in combination with amine quenchers to further improve the contrast between exposed and unexposed areas, thereby improving the low-reflection ratio (LWR). Preferably, triphenylthiocamphor sulfonate and tri-n-pentylamine are used as a quencher combination, or triphenylthiocamphor sulfonate and tri-n-octylamine are used as a quencher combination, and more preferably, triphenylthiocamphor sulfonate and tri-n-pentylamine are used as a quencher combination.

[0112] In this invention, the acidity of the quencher is required to be lower than that of the photoacid, so that the quencher can capture the excess acid compounds generated by PAG to prevent other areas of the matrix resin that have not been exposed to light from also undergoing denaturation.

[0113] Matrix resin

[0114] In this invention, the matrix resin is a polyacrylate derivative. The polyacrylate derivative matrix resin allows light with wavelengths of 193 nm and below to pass through, thereby ensuring that other components in the composition can be irradiated by light.

[0115] In this invention, the matrix resin is a ternary copolymer resin, and its repeating unit is:

[0116]

[0117] Where R AEach is an independent hydrogen atom or a methyl group; X1 and X2 are independent acid-unstable groups; Y is a polar group containing one or more combinations of cyano, carbonyl, carboxyl, ether bond, ester bond, sulfonate bond, carbonate bond, lactone ring, sulcinolone ring, and carboxylic anhydride.

[0118] In this invention, the acid-indestructible groups X1 and X2 can react with acids, thereby changing the solubility of the matrix resin, thus enabling the photolithography of pre-designed patterns on the matrix resin. Specifically, each of the X1 and X2 groups independently comprises one or more combinations of the following structures:

[0119]

[0120] The preferred acid-unstable groups X1 and X2 are respectively:

[0121]

[0122] The Y group is one or more combinations of the following structures:

[0123]

[0124] The preferred Y group is:

[0125]

[0126] The matrix resin is generally formed by polymerization of acrylate derivatives. For example, when the X1 and X2 groups satisfy the above structural formula, the synthetic monomers corresponding to the repeating units are generally:

[0127]

[0128] Preferred options are:

[0129]

[0130] Similarly, when the Y group satisfies the above structural formula, the synthetic monomers corresponding to its repeating units are generally:

[0131]

[0132] Preferred options are:

[0133]

[0134] In addition, the weight-average molecular weight (Mw) of the matrix resin is generally controlled in the range of 1000 to 10000 g / mol, preferably 3000 to 8000 g / mol. By controlling Mw within this range, the matrix resin has sufficient etch resistance and also avoids any resolution degradation caused by the inability to establish a dissolution rate difference before and after exposure.

[0135] Mw can be measured relative to a polystyrene standard using gel permeation chromatography (GPC) with tetrahydrofuran (THF) as the solvent. Specifically, an Agilent GPC column can be used, with a flow rate of 1.0 mL / min, using tetrahydrofuran as the eluent, and a column temperature of 40 °C, to determine the polystyrene using GPC with monodisperse polystyrene as the standard.

[0136] Furthermore, as pattern regularity becomes increasingly finer, the influence of molecular weight and dispersion becomes more pronounced. Therefore, to formulate resist compositions suitable for high-resolution pattern formation, the polymer should preferably have a narrow dispersion of 1.0 to 2.0 (dispersion is expressed as Mw / Mn, where Mn is the number-average molecular weight). A narrower dispersion facilitates the formation of more precise lithographic patterns on the matrix resin. If the polymer has a broad molecular weight distribution or dispersion, it indicates the presence of lower and higher molecular weight polymer fractions, which may result in foreign matter remaining on the pattern or deterioration of the pattern outline.

[0137] When the matrix resin polymer contains the above three repeating units, the molar fraction of each unit preferably falls within the following range (mol%), but is not limited thereto: (I) preferably 5-40 mol%, more preferably 10-30 mol%, of at least one repeating unit having formula (a); (II) preferably 20-60 mol%, more preferably 30-50 mol%, of at least one repeating unit having formula (b); (III) preferably 30-70 mol%, more preferably 40-60 mol%, of at least one repeating unit having formula (c). Wherein, unit (a) is a repeating unit with an X1 group, unit (b) is a unit with an X2 group, and unit (c) is a unit with a Y group.

[0138] Fluorine resin

[0139] In the resist composition of the present invention, the fluorinated resin tends to separate on the resist surface after spin-coating the resist composition. Due to the presence of the fluorinated resin, water and water-soluble components are less likely to seep out from the resist film formed by the resist composition. Therefore, the resist composition containing the fluorinated resin can effectively protect the exposure lens of the lithography machine. In addition, the fluorinated resin also needs to contain specific acid-dissociable groups, so that its solubility in alkaline development after exposure and PEB is increased, thereby enabling it to be removed and reducing defects after development.

[0140] Specifically, the repeating unit of the fluorinated resin is as follows:

[0141]

[0142] Where R includes one or more combinations of hydrogen atoms, fluorine atoms, methyl groups, or trifluoromethyl groups; L G These are acid-labile groups; please refer to the foregoing descriptions of X1 and X2 in this invention for details. f5 It is a fluorinated hydrocarbon with 1 to 30 carbon atoms.

[0143] L G Preferred options are:

[0144]

[0145] R f5 Including but not limited to:

[0146]

[0147] Preferred options are:

[0148]

[0149] solvent

[0150] In a photoresist composition, organic solvents dissolve other components, ensuring the homogeneity of the composition. This allows for the formation of higher-resolution lithographic patterns during application. There are no specific limitations on the type of organic solvent, as long as it can dissolve the other components. Examples include ketones such as cyclohexanone and methyl-2-n-pentyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, and 1-methoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, and propylene glycol dimethyl ether; esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and ethyl lactate; and lactones such as γ-butyrolactone.

[0151] In this invention, the organic solvent can be any one or more mixed solvents. To ensure good solubility, the preferred organic solvent is generally one or more combinations of propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone, and a more preferred organic solvent is a mixed solvent of propylene glycol monomethyl ether acetate, cyclohexanone, and γ-butyrolactone.

[0152] In this invention, specifically, the photoacid generator (A), quencher (B), matrix resin (C), and fluorinated resin (D) of the resist composition are respectively:

[0153]

[0154] The solvent (E) is a mixed solution of propylene glycol monomethyl ether acetate, γ-butyrolactone and cyclohexanone.

[0155] The above-mentioned resist composition is the most preferred combination. It has good solution uniformity and can also reduce acid diffusion length and improve the LWR performance of photolithographic patterns.

[0156] <Pattern Formation Methods>

[0157] A fourth aspect of the present invention provides a pattern forming method, wherein when a photolithographic pattern is formed using the resist composition of the third aspect of the present invention, the following steps are generally performed:

[0158] S1, Film formation: The photoresist composition described in the third aspect of the present invention is coated on a substrate and the photoresist composition described in the third aspect of the present invention is cured to form a photoresist film.

[0159] In this step, a spin coater is typically used to coat the resist composition onto the substrate, and then a drying process is used to cure the resist composition and form a photoresist film.

[0160] S2, Immersion Exposure: Light of a specific wavelength is transmitted through a liquid medium and then irradiated onto a specific area of ​​the photoresist film for exposure.

[0161] In this step, light is typically passed through a mask so that it illuminates a specific area of ​​the photoresist film. The liquid medium is usually water. The light first passes through the mask, then through the liquid medium, and then illuminates the surface of the photoresist film for exposure.

[0162] S3, Development: The photoresist film is treated with an alkaline aqueous solution.

[0163] In this step, an alkaline aqueous solution is used to remove the photoresist film from the exposed area, thereby forming a high-resolution pattern on the surface of the photoresist film.

[0164] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0165] Preparation Example 1

[0166] This embodiment provides an onium salt compound PAG1, the specific synthetic route of which is as follows:

[0167] (1) Synthetic intermediate A:

[0168] Carbonyl diimidazole (CDI, 16.2 g) was added to 500 mL of a tetrahydrofuran solution of 17.49 g of 2-bromo-2,2-difluoroacetic acid, and the mixture was stirred at room temperature for 2 hours. The mixture was then heated to 70 °C, and the intermediate 5-hydroxy-2-adamantanone (16.22 g) was added to the reaction mixture. The reaction was carried out at 70 °C for 16 hours under nitrogen protection.

[0169] After the reaction was complete, the solvent was removed under reduced pressure, and the remaining oily substance was dissolved in 200 mL of dichloromethane. The dichloromethane containing the oily substance was then washed twice with 200 mL of NH4Cl solution, followed by one wash with 200 mL of water. After washing, the dichloromethane solution containing the oily substance was dried with MgSO4, and the dichloromethane was removed under reduced pressure to obtain 21.33 g of intermediate A. The specific reaction formula is as follows:

[0170]

[0171] (2) Synthetic intermediate C:

[0172] Add p-toluenesulfonic acid (TsOH, 0.875 g) to 500 mL of tetrahydrofuran solution of A (21.33 g), and stir the mixture at room temperature for 2 hours. Then heat the mixture to 70 °C, and add B (22.08 g) to the reaction. React at 50 °C for 16 hours under nitrogen protection.

[0173] After the reaction was complete, the solvent was removed under reduced pressure, and the remaining oily substance was dissolved in 200 mL of dichloromethane. The dichloromethane containing the oily substance was then washed twice with 200 mL of NH4Cl solution, followed by one wash with 200 mL of water. After washing, the dichloromethane solution containing the oily substance was dried with MgSO4, and the dichloromethane was removed under reduced pressure to obtain 31.98 g of intermediate C. The specific reaction formula is as follows:

[0174]

[0175] (3) Dissolve intermediate C (31.98 g) in 200 mL of acetonitrile, and dissolve sodium dithionite (1.74 g) and sodium bisulfite (10 g) in 200 mL of deionized water. Add the stirred acetonitrile solution containing intermediate C to the aqueous solution to form a mixed solution, stir at 70°C for 16 hours, and then... 19F-NMR was used to determine if the reaction was complete. After complete reaction, 100 mL of water, 50 mg of Na₂WO₄·2H₂O, and 14.5 g of H₂O₂ (30 wt% aqueous solution) were added to the reaction system, and the mixture was stirred at room temperature for 16 hours. After the reaction was complete, the organic phase was evaporated on a rotary evaporator, and the residual solid was dissolved in 100 L of acetone. The solution was then slowly poured into 2 L of methyl tert-butyl ether. The solvent was removed by decantation to obtain a waxy product, which was further dried under reduced pressure to obtain 22.52 g of crude intermediate D. The crude product was used directly in the next step. The reaction formula is as follows:

[0176]

[0177] (4) Synthesis of PAG1: Intermediate D (22.52 g) and triphenyl sulfide bromide (TPSBr, 11.63 g) were added to a mixed solution of 200 mL dichloromethane and 200 mL deionized water, and the mixture was stirred overnight at room temperature. After the reaction was complete, the aqueous phase and organic phase were separated, and the organic phase was washed 5 times with 200 L of deionized water. The concentrated and separated organic phase was poured into methyl tert-butyl ether to generate 22.16 g of photoacid generator PAG1, as shown in the following reaction formula:

[0178]

[0179] The purity of the PAG1 sample was determined by HPLC-MS. The purity of the cation was 99.8% as detected by UV at 220 nm, 99.6% as detected by cation chromatography-mass spectrometry, and 99.7% as detected by anion chromatography-mass spectrometry. LCMS: cation 263; anion 703.

[0180] Preparation Example 2

[0181] Following the above synthesis method, Example 2 provides an onium salt compound named PAG2, with the following specific structure:

[0182]

[0183] Example

[0184] This invention provides resist compositions with different components to investigate the effect of photoacid generators on the performance of the resist compositions. The components of the resist compositions of this application are specifically described below:

[0185] A represents the photoacid generator, and A1 to A2 correspond to PAG1 to PAG2 respectively. The specific structural formulas of A3 to A5, which correspond to PAG3 to PAG5 respectively, are as follows:

[0186]

[0187] B represents the quenching agent, and B1 is triphenylthiosalicylate, B2 is triphenylthiocamphorsulfonate, B3 is tri-n-pentylamine, and B4 is tri-n-octylamine.

[0188] C represents the matrix resin. 13 C-NMR analysis showed that the molar ratio of a to b, c was 43:5:52. The repeating unit was:

[0189]

[0190] D represents fluorinated resin. 13 C-NMR analysis showed that the molar ratio of d to e was 81:19. Its repeating unit was:

[0191]

[0192] E represents an organic solvent, and E1 represents propylene glycol monomethyl ether acetate, E2 represents γ-butyrolactone, and E3 represents cyclohexanone.

[0193] The specific components and formulations of various resist compositions are shown in the table below:

[0194] Table 1. Components and proportions of the resist compositions in the examples and comparative examples.

[0195]

[0196] For the resist compositions of Examples 1-6 and Comparative Examples 1-3, the sensitivity and LWR were tested according to the following evaluation method.

[0197] An underlayer antireflective film with an average thickness of 105 nm was formed by applying an underlayer antireflective film forming composition (trade name "ARC66") to the surface of a 12-inch silicon wafer using a spin coater (Tokyo Electron Ltd.'s "CLEANTRACKACT12").

[0198] The resist compositions from all examples and comparative examples were applied to the surface of a 12-inch silicon wafer using a spin coater, and then baked at 120°C for 60 seconds, followed by cooling at 23°C for 30 seconds to form a resist film with an average thickness of 85 nm. Next, exposure was performed using an ArF excimer laser immersion exposure system (model "TWINSCANXT-1980Di", manufactured by ASML Co.) under optical conditions through a mask pattern with lines of 38 nm and a spacing of 76 nm. The exposure parameters were: NA 1.35, dipole illumination (0-0.98 / 0.90). After exposure, PEB was performed at 85°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38% (w / w) tetramethylammonium hydroxide (TMAH) aqueous solution. After development, the film was rinsed with water and then dried to form a positive resist pattern.

[0199] (1) Sensitivity test

[0200] The exposure dose used to form a 38 nm line and 76 nm pitch exposure pattern on the resist composition after ArF exposure is defined as the optimal exposure dose (Eop), and is used as the sensitivity Eop (unit: mJ / cm). 2 ).

[0201] (2) LWR test

[0202] The line width of a 1:1 Line / Space pattern at 36 nm was measured using a SEM (scanning electron microscope) to determine the line width variation (30 points were measured, and the 3σ value was calculated), denoted as LWR. A smaller LWR value indicates less fluctuation in the line pattern and a better outline.

[0203] The measurement results are shown in the table below:

[0204] Table 2 Performance test results of the examples and comparative examples

[0205]

[0206]

[0207] As shown in Table 2, the resist composition of the present invention, because it contains onium salt PAG, is particularly suitable for ArF immersion lithography, as it forms patterns with high resolution, high sensitivity and low LWR.

[0208] It should be noted that, based on the explanations and descriptions in the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some equivalent modifications and alterations to the present invention should also be within the scope of protection of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the invention.

Claims

1. An onium salt compound, characterized by, A structure general formula is: ， Wherein, R1, R2, R3, R4 are each independently one of cyclopentane group and cyclohexane group or a combination of both; Cation Z + selected from sulfonium cations.

2. The onium salt compound of claim 1, wherein Said R1, R2, R3, R4 are each cyclohexane group.

3. The onium salt compound of claim 1, wherein Said onium salt compound is selected from one of the following compounds: 。 4. The onium salt compound of claim 3, wherein Said onium salt compound is: 。 5. A photoacid generator characterized by, Containing the onium salt compound of any one of claims 1-4.

6. A resist composition, characterized by comprising: Including the photoacid generator, quencher, base resin, fluorine-containing resin and solvent of claim 5; said quencher is selected from a combination of ionic quencher and amine quencher; the cation of said ionic quencher is selected from one or more combinations of the following structures: 、 、 、 、 、 ； The anion of said ionic quencher is selected from one or more combinations of the following structures: 、 、 、 、 ； The amine quencher is selected from one or more combinations of the following structures: ； Said base resin is a polyacrylate derivative.

7. The resist composition according to claim 6, wherein The cation of said ionic quencher is: ； The anion of said ionic quencher is: 、 ； The amine quencher is: 、 The quencher combination is a combination of triphenylsulfonium camphorsulfonate and tri-n-pentylamine, triphenylsulfonium camphorsulfonate and tri-n-octylamine.

8. The resist composition according to claim 7, wherein The anion of said ionic quencher is: ； The amine quencher is: ； The quencher combination is a combination of triphenylsulfonium camphorsulfonate and tri-n-pentylamine.

9. The resist composition of claim 6, wherein Said base resin is a terpolymer resin, and the repeating unit thereof is: ， wherein R A each independently is a hydrogen atom or a methyl group; X1and X2each independently are an acid labile group, the acid labile groups X1and X2each independently are selected from one of the following structures: 、 、 、 、 、 、 、 、 、 、 、 ； The Y group is selected from one of the following structures: 、 、 、 、 、 、 。 10. The resist composition according to claim 9, wherein Said acid-labile groups X1 and X2 are respectively: 、 ； The Y group is: 。 11. The resist composition of any one of claims 6 to 10, wherein The photoacid generator (A), quencher (B), base resin (C) and fluorine-containing resin (D) of said resist composition are respectively: Said solvent (E) is a mixed solution of propylene glycol monomethyl ether acetate, gamma-butyrolactone and cyclohexanone.

12. A pattern forming method, characterized by, Including the following steps: S1, film formation: coating the resist composition of any one of claims 6-10 on a substrate and curing the resist composition of any one of claims 6-10, thereby forming a photoresist film. S2, liquid immersion exposure: a specific wavelength of light is transmitted through a liquid medium and then irradiated on a specific area of the photoresist film for exposure. S3, development: treating the photoresist film with an alkaline aqueous solution.

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