Photoacid generator, resist composition, and pattern forming method

Abstract

The invention provides a photoacid generator, a resist composition and a pattern forming method, and relates to the technical field of photoetching materials. The photoacid generator has a general formula represented by a structural formula (1), and in the structural formula (1), a is 1 or 2; x is-CO-or dicarboximide forming a five-membered ring with two sides of the-CO-, or X is-CH2CO-or dicarboximide forming a six-membered ring with two sides of the-CH2CO-; y and a carbon atom on the right side of Y form a C6-C10 monocyclic saturated aliphatic hydrocarbon ring, a C6-C14 bridge ring and a C6-C14 aromatic ring together. The photoacid generator in the resist composition can improve the LER performance of a resist film pattern and improve the development defect of a resist film.

Description

Technical Field

[0001] The present application relates to the technical field of photolithographic materials, and in particular to a photoacid generator, a resist composition, and a pattern forming method. Background Art

[0002] Photolithography technology has advanced rapidly with the continued development of integrated circuits. From g-line (436 nm) and i-line (365 nm), to deep ultraviolet (DUV) 248 nm and 193 nm excimer lasers, and then to extreme ultraviolet (EUV), the wavelength of the exposure light source has gradually shortened. At the same time, this has also increased the critical demand for resist compositions with higher sensitivity and resolution. Currently, the process dominated by wafer fabs is lithography using light waves of 193 nm and below (ArF lithography), which can be divided into 193 nm dry lithography and 193 nm immersion lithography.

[0003] ArF lithography technology nodes, due to the small size of the images formed, promote the miniaturization of patterns by using short-wavelength radiation such as ArF excimer lasers, or by using liquid immersion exposure methods (liquid immersion lithography) in which the space between the lens and the resist film of the exposure device is filled with a liquid medium. The photoacid generator in the resist composition is particularly important. Since most photoacid generators are ionic compounds with poor solubility, they cannot be evenly distributed in the resist film, resulting in the line edge roughness (LER) of the resist film pattern being affected by the acid diffusion distance. During the post-exposure bake (PEB) stage, excessive free acid migrates and causes excessive acid diffusion across the entire resist film, thereby increasing the LER. Therefore, it is necessary to address the solubility of the photoacid generator and the unpredictability of acid diffusion to reduce development defects. Summary of the Invention

[0004] The present application provides a photoacid generator, a resist composition, and a pattern forming method. The photoacid generator in the resist composition can improve the LER performance of the resist film pattern, and at the same time can improve the solubility of the resist composition in the developer tetramethylammonium hydroxide, thereby improving the development defects of the resist film.

[0005] In a first aspect, the present application provides a method comprising: the photoacid generator has a general formula represented by structural formula (1),

[0006] (1)

[0007] In the structural formula (1), a is 1 or 2;

[0008] R1 is a perfluoro-substituted butyl group, a trifluoromethyl group, a tridecafluorohexyl group, a heptadecafluorooctyl group, a 2,2,2-trifluoroethyl group, a 1,1-difluoroethyl group, a 1,1-difluoropropyl group, a 1,1,2,2-tetrafluoropropyl group, a 3,3,3-trifluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, a norbornyltetrafluoroethyl group, adamantane-1,1,2,2-tetrafluoropropyl group, or a bicyclo[2.2.1]heptane-tetrafluoromethyl group;

[0009] X is -CO-, and a dicarboximide is formed with both sides thereof to form a five-membered ring, or X is -CH2CO-, and a dicarboximide is formed with both sides thereof to form a six-membered ring;

[0010] Y and the carbon atom to its right form a C6-C10 monocyclic saturated aliphatic hydrocarbon ring, a C6-C14 bridged ring, or a C6-C14 aromatic ring.

[0011] In one possible embodiment, in the structural formula (1), X is -CO-, and forms a dicarboximide with a five-membered ring on both sides thereof, and Y forms a C6~C8 monocyclic saturated aliphatic hydrocarbon ring or a C6~C10 bridged ring together with the two carbon atoms on its right side, or X is -CH2CO-, and forms a dicarboximide with a six-membered ring on both sides thereof, and Y forms a C6~C10 bridged ring, a naphthalene ring, or an anthracene ring together with the three carbon atoms on its right side thereof.

[0012] In one possible embodiment, the photoacid generator is selected from one or more of the following structures:

[0013] .

[0014] In a possible implementation manner, in the structural formula (1), a is 1.

[0015] In one possible embodiment, the photoacid generator is selected from one or more of the following structures:

[0016] .

[0017] In a possible embodiment, in the structural formula (1), X is -CO-, forming a five-membered ring of dicarboximide with its two sides, and Y forms a C6-C10 bridge ring with its two carbon atoms on the right.

[0018] In a possible embodiment, in the structural formula (1), R1 is a perfluorosubstituted butyl group or a trifluoromethyl group.

[0019] In a second aspect, the present application provides a resist composition, characterized in that it comprises: a photoacid generator (A) as described in any embodiment of the first aspect, a main resin (B), an acid diffusion controller (C), a fluorine-containing resin (D) and an organic solvent (E).

[0020] In one possible embodiment, based on 100 parts by weight of the main resin (B), the amount of the photoacid generator (A) added is 0.1 to 20 parts by weight, the amount of the acid diffusion controller (C) added is 0.1 to 5 parts by weight, and the amount of the fluorine-containing resin (D) added is 0.1 to 30 parts by weight.

[0021] In a third aspect, the present application provides a method for forming a resist pattern, characterized in that it comprises the following steps:

[0022] S1, coating: coating a substrate with the resist composition according to any one embodiment of the second aspect and curing the substrate to form a photoresist film;

[0023] S2, immersion exposure: After drying, light of a specific wavelength is passed through the liquid medium, and then an ArF excimer laser is used to irradiate specific areas of the photoresist film for immersion exposure;

[0024] S3, development: after baking, the exposed photoresist film is developed using a developer to obtain a photoresist pattern.

[0025] In the above technical solution, by adding a photoacid generator such as structural formula (1) to the resist composition, the lactam generated by the photoacid generator during the reaction process can act as an acid diffusion controller, thereby inhibiting the diffusion of acid in the resist film and improving the LER performance of the resist film pattern. In addition, the lactam contains a carboxylic acid substituent, which improves the solubility of the resist composition in the developer tetramethylammonium hydroxide and improves the development defects of the resist film. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0027] It should be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0028] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0029] It should be noted that the following embodiments are examples of the present application and are only used to illustrate the present application, not to limit the present application. Other combinations and various improvements within the scope of the present application can be made without departing from the spirit or scope of the present application.

[0030] The photoacid generator, resist composition and pattern forming method provided in this application are described in detail below.

[0031] The photoacid generator of the embodiment of the present application has the general formula represented by structural formula (1),

[0032] (1)

[0033] In the structural formula (1), a is 1 or 2; R1 is a perfluorosubstituted butyl group, a trifluoromethyl group, a tridecafluorohexyl group, a heptadecafluorooctyl group, a 2,2,2-trifluoroethyl group, a 1,1-difluoroethyl group, a 1,1-difluoropropyl group, a 1,1,2,2-tetrafluoropropyl group, a 3,3,3-trifluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, a norbornyltetrafluoroethyl group, an adamantane-1,1,2,2-tetrafluoropropyl group, or a bicyclo[2.2.1]heptane-tetrafluoromethyl group; X is -CO-, and forms a dicarboximide with a five-membered ring on both sides thereof, or X is -CH2CO-, and forms a dicarboximide with a six-membered ring on both sides thereof; and Y, together with the carbon atom to its right, forms a C6-C10 monocyclic saturated aliphatic hydrocarbon ring, a C6-C14 bridged ring, or a C6-14 aromatic ring.

[0034] When radiation is irradiated to the photoacid generator of the above structure, the N-O bond of the sulfonamide ester is broken to form dicarboximide compounds and sulfonic acid compounds. The dicarboximide compounds are further decomposed into lactam and CO2. The reaction process is as follows:

[0035]

[0036]

[0037] The present application is by adding the photoacid generator of the above structure into the resist composition, making the resist composition deprotonated to release corresponding photoacid, the photoacid produced can make the main resin in the resist deprotected, and then change the polarity of the resin, thereby changing the solubility of the main resin in the exposure area, increasing the contrast of the exposure area and the non-exposure area. Simultaneously, because the lactam produced in the reaction process contains a carboxylic acid substituent, when using tetramethylammonium hydroxide (TMAH) as a developer, the resist composition has higher solubility in TMAH, thereby also effectively improving the effect of the development defect of the resist film. In addition, lactam can play the role of acid diffusion control agent, thereby can suppress the diffusion of acid in the resist film, promote the LER performance of the resist film pattern.

[0038] Furthermore, in the structural formula (1), X is -CO-, and forms a dicarboximide with a five-membered ring on both sides thereof, and Y forms a C6~C8 monocyclic saturated aliphatic hydrocarbon ring or a C6~C10 bridged ring together with the two carbon atoms on the right side thereof; or, X is -CH2CO-, and forms a dicarboximide with a six-membered ring on both sides thereof, and Y forms a C6~C10 bridged ring, a naphthalene ring, or an anthracene ring together with the three carbon atoms on the right side thereof.

[0039] The photoacid generator is selected from one or more of the following structures:

[0040] .

[0041] Because structural formula (1) contains a carboxyl group, its solubility in alkaline developer is improved, thereby reducing the insoluble components in the exposed area. However, when the carboxyl group is directly bonded to the ring, when a = 2 (i.e., the photoacid generator contains two carboxyl groups), structural formula (1) itself will condense, increasing the insoluble components after development and increasing the risk of development defects. When a is 1 (i.e., the photoacid generator contains only one carboxyl group), the degree of freedom is reduced, so solids will not precipitate, further improving the suppression effect of development defects. To further improve the number of development defects, in structural formula (1) of the present application, a = 1.

[0042] Preferably, the photoacid generator is selected from one or more of the following structures:

[0043] .

[0044] Furthermore, in the structural formula (1) of the present application, Y and the carbon atom to its right form a C6~C10 bridged ring. When dicarboximide is exposed to deep ultraviolet light (DUV, 193 nm), the photoacid generator synthesized from the bridged cycloalkane skeleton can improve the transparency of the resist film and efficiently release strong acid, thereby improving the sensitivity of the resist composition. At the same time, the fused ring structure of the bridged cycloalkane can effectively limit the lateral diffusion of the photoacid molecules in the resist film, thereby facilitating the LER performance of the resist film pattern. Preferably, the photoacid generator is selected from one or more of the following structures:

[0045] .

[0046] Furthermore, in the structural formula (1) of the present application, X is -CO-, forming a five-membered ring of dicarboximide with its two carbon atoms on both sides, and Y forms a C6-C10 bridge ring with its two carbon atoms on the right. Because the six-membered ring is more rigid and stable than the five-membered ring, the photoacid generator synthesized from the five-membered ring of dicarboximide skeleton is more likely to undergo the above-mentioned hydrolysis reaction to form lactam under deep ultraviolet (DUV, 193 nm) exposure.

[0047] Furthermore, in the structural formula (1) of the present application, R1 is a perfluorosubstituted butyl group or a trifluoromethyl group. Since the perfluorosubstituted butyl group and the trifluoromethyl group have strong electron-withdrawing ability, the perfluorosubstituted butyl group and the trifluoromethyl group are preferably selected from the group consisting of a fluoroalkyl group and a fluoroalkyl group. - By bonding a highly electron-withdrawing perfluorinated alkyl group at a relatively close position, the acid strength can be further increased, thereby further improving the sensitivity of the resist composition.

[0048] Further preferably, the photoacid generator is selected from one or more of the following structures:

[0049] .

[0050] The present application also provides a resist composition comprising a photoacid generator (A), a main resin (B), an acid diffusion controller (C), a fluorine-containing resin (D), and an organic solvent (E). Each component is described below in turn.

[0051] <Photoacid generator (A)>

[0052] The photoacid generator (A) is as described above. The amount of the photoacid generator (A) added is preferably 0.1 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 5 parts by mass or more, based on 100 parts by mass of the main resin (B). Furthermore, the amount of the photoacid generator (A) added is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, based on 100 parts by mass of the main resin (B).

[0053] <Main resin (B)>

[0054] In the present application, the main resin (B) is a polyacrylate derivative having the general formula represented by structural formula (2):

[0055] (2)

[0056] In the structural formula (2), R2 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; R3 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms; R4 and R5 are independently a monovalent chain hydrocarbon group having 1 to 8 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 12 carbon atoms, or a divalent alicyclic hydrocarbon group having 3 to 12 carbon atoms formed by combining R4 and R5 with each other and the carbon atoms to which R4 and R5 are bonded.

[0057] The main resin (B) comprises repeating units (B-1), repeating units (B-2), and repeating units (B-3). Among them, the repeating unit (B-1) is an acid-sensitive group repeating unit, R2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and the monovalent alicyclic hydrocarbon group with 3 to 20 carbon atoms represented by R3 to R5 can be a group obtained by removing one hydrogen atom from a monocyclic saturated alicyclic hydrocarbon, an unsaturated alicyclic hydrocarbon, or an alicyclic polycyclic hydrocarbon with 3 to 20 carbon atoms. Specific examples of these alicyclic hydrocarbons include monocyclic saturated alicyclic hydrocarbons such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; and monocyclic unsaturated alicyclic hydrocarbons such as cyclopentene, cyclohexene, cycloheptene, cyclooctene, and cyclodecene. The repeating unit (B-1) can be listed as follows:

[0058]

[0059] The repeating unit (B-2) is a lactone group repeating unit; this facilitates adjusting the solubility of the main resin (B) in the developer, improving adhesion to the substrate, and enabling enhanced lithographic performance, such as resolution. In the repeating unit (B-2), R2 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and R3-R4 comprise at least one structural unit selected from the group consisting of a cyclic lactone structure, a cyclic carbonate structure, and a sultone structure. Examples of the repeating unit (B-2) include:

[0060]

[0061] The repeating unit (B-3) is a polar group repeating unit. The repeating unit (B-3) adjusts the solubility of the main resin (B) in the developer, thereby improving the resolving power and other lithographic properties of the composition. The polar group of the repeating unit (B-3) is R2, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and R3-R4 are linear or cyclic alkyl hydrocarbons containing hydroxyl groups, carboxyl groups, cyano groups, nitro groups, or polar groups. Examples of the repeating unit (B-3) are as follows:

[0062]

[0063] In the present application, the main resin (B) is a ternary or tetrapolymer resin comprising at least one repeating unit of formula (B-1). Among all the structural units constituting the main resin (B), the content of structural unit (B-1) is 10 to 90 mol%, more preferably 30 to 60 mol%; the content of at least one repeating unit of formula (B-2) is 5 to 30 mol%, more preferably 15 to 30 mol%; and the content of at least one repeating unit of formula (B-3) is 5 to 30 mol%, more preferably 15 to 30 mol%.

[0064] <Acid Diffusion Controller (C)>

[0065] The acid diffusion controller (C) inhibits the diffusion of acid generated by the photoacid generator during exposure into the resist film, thereby suppressing chemical reactions caused by the acid in unexposed areas. By incorporating the acid diffusion controller (C) into the resist composition, the performance and lithographic characteristics of the resist film can be improved, particularly by enhancing the contrast and resolution of the resist film.

[0066] Examples of the acid diffusion controller (C) include nitrogen-containing compounds and photodegradable bases. The photodegradable base used herein is preferably a triarylsulfonium salt. In this application, the acid diffusion controller (C) has the following structures: C1 to C3. One type of acid diffusion controller may be used alone, or two or more types may be used in combination.

[0067]

[0068] In the case where the resist composition contains an acid diffusion controller (C), the addition amount of the acid diffusion controller (C) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and then preferably 3 parts by mass or more, based on the addition amount of the main resin (B) as 100 parts by mass. In addition, the addition amount of the acid diffusion controller (C) is preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, and then preferably 4 parts by mass or less, based on the addition amount of the main resin (B) as 100 parts by mass. By setting the addition amount of the acid diffusion controller (C) to the range, the LWR performance of the resist composition can be further improved. As the acid diffusion controller (C), one can be used alone, or two or more can be used in combination.

[0069] <Fluorine-containing resin (D)>

[0070] The fluorine-containing resin (D) is more likely to be present in the surface layer of the resist film than the main resin (B). Since the CF bond of the fluorine-containing resin (D) has low surface energy, a unique molecular structure, and stable chemical properties, it can improve the hydrophobicity of the resist film surface during water immersion exposure. The fluorine-containing resin (D) has the general formula represented by the structural formula (3),

[0071] (3)

[0072] Wherein, R2 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group; Z is an alkyl group having 1 to 10 carbon atoms, and R7 is a perfluoroalkyl group having 1 to 10 carbon atoms. Preferably, Z is 1 to 2 and R7 is 1 to 2 carbon atoms. Examples of fluorine-containing resins (D) include the following:

[0073] (D-1)

[0074] In the case where the resist composition contains the fluorine-containing resin (D), the amount of the fluorine-containing resin (D) is preferably 0.1 parts by mass or more, more preferably 2 parts by mass or more, and further preferably 5 parts by mass or more, based on 100 parts by mass of the amount of the main resin (B) added. In addition, the amount of the fluorine-containing resin (D) is preferably 30 parts by mass or less, and more preferably 10 parts by mass or less, based on 100 parts by mass of the amount of the main resin (B) added.

[0075] <Organic solvent (E)>

[0076] The organic solvent (E) is not particularly limited as long as it is a solvent capable of dissolving or dispersing the components in the resist composition. As the organic solvent (E), alcohols, ethers, ketones, esters, and the like can be exemplified.

[0077] As the alcohols, 4-methyl-2-pentanol, n-hexanol, 1,2-propanediol, and the like can be exemplified. As the ethers, propylene glycol monomethyl ether (PGME), diisopentyl ether, tetrahydrofuran, tetrahydropyran, and the like can be exemplified. As the ketone solvents, cyclohexanone, methyl-2-n-pentyl ketone, and the like can be exemplified. As the ester solvents, propylene glycol monomethyl ether acetate (PGMEA), n-butyl acetate, ethyl lactate (EL), γ-butyrolactone, and the like can be exemplified.

[0078] One or more of propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), ethyl lactate (EL), and γ-butyrolactone is preferable.

[0079] <Pattern forming method>

[0080] The present application also provides a pattern forming method, including: a process of applying a resist composition on one surface of a substrate (hereinafter, also referred to as "coating film process"); a process of exposing the resist film obtained by the application process (hereinafter, also referred to as "exposure process"); and a process of developing the exposed resist film (hereinafter, also referred to as "development process").

[0081] Coating film process

[0082] The resist composition is coated on a substrate generally using a conventional device such as a spin coater. The resist composition is preferably filtered with a filter having a pore size of 0.2 μm before coating. Examples of the substrate include a silicon wafer or a quartz wafer on which a sensor, a circuit, a transistor, or the like is to be formed. After coating, a soft bake (SB) is performed to volatilize a solvent in the coating film. The temperature of the SB is preferably 60°C or higher, more preferably 80°C or higher. In addition, the temperature of the SB is preferably 140°C or lower, more preferably 120°C or lower. The time of the SB is preferably 5 seconds or longer, more preferably 10 seconds or longer. In addition, the time of the SB is preferably 600 seconds or shorter, more preferably 300 seconds or shorter. The average thickness of the resist film formed is preferably 100 nm to 1000 nm, more preferably 100 nm to 500 nm.

[0083] Exposure step

[0084] The composition layer thus obtained is generally exposed using a dry exposure device or a liquid immersion exposure device. Exposure is generally performed through a mask corresponding to a desired pattern. Various types of exposure light sources can be used, such as irradiation using an ultraviolet laser such as a KrF excimer laser (wavelength: 248 nm), an ArF excimer laser (wavelength: 193 nm), an F2 excimer laser (wavelength: 157 nm), an immersion ArF-i excimer laser (wavelength: 134 nm). In addition, the exposure device can be an exposure device that radiates an electron beam or extreme ultraviolet rays (EUV). After the exposure, a post-exposure bake (PEB) is performed, and in the exposed portion of the resist film, the dissociation of the acid-sensitive group contained is promoted using an acid generated by the post-exposure light, and the sensitivity is further improved. The temperature and the time of the PEB directly affect the diffusion range and the reaction rate of the photoacid, and further affect the critical dimension (CD), the sidewall angle, and the line edge roughness (LER) of the pattern after development.

[0085] The resist composition of the present application is preferably exposed using an ArF immersion exposure device. The temperature of the PEB is preferably 50°C or higher, more preferably 80°C or higher. In addition, the temperature of the PEB is preferably 180°C or lower, more preferably 130°C or lower. The time of the PEB is preferably 5 seconds or longer, more preferably 10 seconds or longer. In addition, the time of the PEB is preferably 600 seconds or shorter, more preferably 300 seconds or shorter.

[0086] Development step

[0087] After the heat treatment, the resist film is developed, generally using an alkaline developer solution. Development here refers to contacting the resist film with an alkaline solution after the heat treatment. Thus, the exposed portion of the resist film is dissolved and removed by the alkaline solution, and the unexposed portion of the composition layer is retained on the substrate, thereby preparing a resist pattern. Here, as the alkaline developer solution, an aqueous solution including tetramethylammonium hydroxide and (2-hydroxyethyl)trimethylammonium hydroxide (common name: choline) can be used. Tetramethylammonium hydroxide developer is preferred. After development, the resist is generally rinsed with a rinse solution such as water and dried.

[0088] The technical solution of the present invention is further described below with reference to specific examples. The abbreviations corresponding to some of the compounds involved in the examples are described below.

[0089] Monomer T-1:

[0090] Monomer T-2:

[0091] Monomer T-3:

[0092] Monomer T-4:

[0093] Monomer T-5:

[0094] AIBN: Azobisisobutyronitrile

[0095] Acid diffusion controller C1:

[0096] Acid diffusion controller C2:

[0097] Organic solvent E1: propylene glycol monomethyl ether acetate (PGMEA)

[0098] Organic solvent E2: propylene glycol monomethyl ether (PGME)

[0099] Organic solvent E3: ethyl lactate (EL)

[0100] Photoacid generator A12:

[0101] Photoacid generator A13:

[0102] Photoacid generator A14:

[0103] Synthesis Example 1 (Synthesis of Main Resin B1)

[0104] A monomer solution was prepared by dissolving monomer (T-1), monomer (T-2), and monomer (T-4) in 2-butanone (200 parts by mass) at a molar ratio of 40 / 40 / 20 (mole %), adding AIBN as an initiator (5 mole % relative to 100 mole % of the total of the monomers used), and stirring. After purging with nitrogen for 30 minutes, the reaction vessel was set to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was set as the start time of the polymerization reaction, and the polymerization reaction was performed for 6 hours. After the polymerization reaction was completed, the polymerization solution was water-cooled and cooled to 30°C or lower. The cooled polymerization solution was poured into methanol (2000 parts by mass), and the white powder that precipitated was separated by filtration. The white powder that was separated by filtration was washed twice with methanol, separated by filtration, and dried at 50°C for 24 hours to obtain resin (B1) in the form of a white powder (yield: 85%). The Mw of the main resin (B1) was 7100, and the Mw / Mn was 1.61.

[0105] Synthesis Example 2 (Synthesis of Main Resin B2)

[0106] A monomer solution was prepared by dissolving monomer (T-2), monomer (T-3), and monomer (T-4) in 2-butanone (200 parts by mass) at a molar ratio of 35 / 45 / 20 (mole %), adding AIBN as an initiator (5 mole % relative to 100 mole % of the total of the monomers used), and stirring. After purging with nitrogen for 30 minutes, the reaction vessel was set to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was set as the start time of the polymerization reaction, and the polymerization reaction was performed for 6 hours. After the polymerization reaction was completed, the polymerization solution was water-cooled and cooled to 30°C or lower. The cooled polymerization solution was poured into methanol (2000 parts by mass), and the white powder that precipitated was separated by filtration. The white powder that was separated by filtration was washed twice with methanol, separated by filtration, and dried at 50°C for 24 hours to obtain resin (B2) in the form of a white powder (yield: 85%). The Mw of the main resin (B2) was 9100, and the Mw / Mn was 1.65.

[0107] Synthesis Example 3 (Synthesis of Fluorine-Containing Resin D1)

[0108] Monomer (T-5) was dissolved in 200 parts by mass of 2-butanone, and AIBN was added as an initiator. Nitrogen was blown into the solution for approximately 10 minutes. The reaction was stirred at 80°C for 6 hours. The mixture was cooled to room temperature, concentrated under reduced pressure, and then injected into methanol (2000 parts by mass) to precipitate the resin, which was then filtered. Drying at 40°C for 24 hours yielded white solid D1 (yield: 85%). The Mw of the fluororesin (D1) was 8100, and the Mw / Mn ratio was 1.55.

[0109] Synthesis Example 4 (Synthesis of Fluorine-Containing Resin D2)

[0110] Monomers (T-5) and (T-1) were dissolved in 200 parts by mass of 2-butanone, and AIBN was added as an initiator. Nitrogen was blown into the solution for approximately 10 minutes. The reaction was stirred at 80°C for 6 hours. The mixture was cooled to room temperature, concentrated under reduced pressure, and then injected into methanol (2000 parts by mass) to precipitate the resin, which was then filtered. Drying at 40°C for 24 hours yielded white solid D2 (yield: 85%). The fluororesin (D2) had an Mw of 7500 and an Mw / Mn ratio of 1.62.

[0111] Synthesis Example 5 (Synthesis of Photoacid Generator A1)

[0112] Under a nitrogen atmosphere, 21.6 g (100 mmol) of tricarboxylic acid compound (I-1), 11 mL (110 mmol) of anhydrous acetic anhydride, and 200 mL of solvent 1,4-dioxane were added and refluxed at 160°C for 4 h. All solvents were dried under reduced pressure, and 10 times the mass of toluene was added to the residue. The mixture was allowed to stand for 4 h to wait for crystals to precipitate, and then dried to obtain the product I-2. 150 mL of pyridine was added to 15 g (75.6 mmol) of compound (I-2) and mixed evenly. Hydroxylamine hydrochloride (5.26 g, 75.6 mmol) was added, and the mixture was heated at 80°C for 15 h. The reaction mixture was poured into 50 mL of 1N HCl. The precipitate was filtered and washed with water, and purified by column chromatography (20% ethyl acetate / petroleum ether) to obtain compound I-3. At 0 ° C, to a mixture of triethylamine 9.49 g (93.81 mmol), compound (I-3) 10 g (46.91 mmol) and ultra-dry DCM 100 mL, trifluoromethylsulfonyl chloride 11.86 g (70.36 mmol) was added dropwise. The mixture was then stirred at room temperature overnight. After completion of the reaction, it was quenched with cold water, diluted with DCM, the organic layer was separated, dried over Na2SO4, and the solvent was removed under vacuum to obtain an orange crude sulfonate, which was purified by column chromatography (20% ethyl acetate / hexane) to obtain photoacid generator A1 as an orange solid in a 60% yield.

[0113]

[0114] I-1 I-2 I-3 A1

[0115] Synthesis Example 6 (Synthesis of photoacid generator A2)

[0116] To a mixture of triethylamine 9.49 g (93.81 mmol), compound (I-3) 10 g (46.91 mmol) and super dry DCM 100 mL at 0°C, dropwise added perfluorobutylsulfonyl chloride 22.41 g (70.36 mmol). Then the mixture was stirred at room temperature overnight. After completion of the reaction, it was quenched with cold water, diluted with DCM, the organic layer was separated and dried over Na2SO4 and the solvent was removed under vacuum to get orange colored crude sulfonate which was purified by column chromatography (20% ethyl acetate / hexane) to get photoacid generator A2 in 60% yield.

[0117]

[0118] I-3 A2

[0119] Synthesis Examples 7~15

[0120] Photoacid generators A3~A11 were synthesized by referring to the routes of synthesis example 5 and synthesis example 6 above, with the difference that the starting materials of (I-1) compound and sulfonyl chloride compound were different, and their structures are shown in Table 1.

[0121] Table 1 Structural formula of photoacid generators A3~A11

[0122] Example 1

[0123] This example provides a resist composition, which is prepared by mixing 100 parts by mass of a main resin (B1), 10.0 parts by mass of a photoacid generator (A1), 5.0 parts by mass of an acid diffusion controller (C2), 1.0 parts by mass of a fluorine-containing resin (D1) (solid content), and 3000 parts by mass of a mixed solvent of organic solvents (E1) / (E2) / (E3) (2500 / 400 / 100 (parts by mass)) as a mixed solvent of organic solvents (E1) / (E2) / (E3), filtering with a membrane filter having a pore size of 0.2 μm, thereby preparing a resist composition.

[0124] Examples 2~13 & Comparative Examples 1~4

[0125] Examples 2~13 & Comparative Examples 1~4 each provide a resist composition, which is prepared by substantially the same method as in Example 1, with the difference that the kind of photoacid generator, main resin, acid diffusion controller, fluorine-containing resin is different, and the specific formulation is shown in Table 2.

[0126] Table 2 Formulations of resist compositions of Examples 1 to 13 and Comparative Examples 1 to 4

[0127] <Patterning (ArF immersion exposure)>

[0128] A spin coater ("CLEAN TRACK ACT 12" manufactured by Tokyo Electron) was used to apply a composition for forming an underlayer film ("ARC66" manufactured by Brewer Science) to a 12-inch silicon wafer, and then heated at 205°C for 60 seconds to form an underlayer film having an average thickness of 100 nm. The ArF immersion exposure resist composition prepared as described above was applied to the underlayer film using the spin coater, and pre-baked (PB) was performed at 100°C for 60 seconds. Thereafter, the film was cooled at 23°C for 30 seconds to form a resist film having an average thickness of 90 nm. Next, an ArF excimer laser immersion exposure apparatus ("TWINSCAN XT-1900i" manufactured by ASML) was used with NA = 1.35, σ = 0.9 / 0. Under optical conditions of 0.7, a mask with 50 nm lines and 100 nm spacing on the wafer was exposed. After exposure, a post-exposure bake (PEB) was performed at 100°C for 60 seconds. The resist film was then developed using a 2.38 wt% TMAH aqueous solution as an alkaline developer. After development, the resist film was rinsed with water and dried to form a positive resist pattern (50 nm line and space pattern).

[0129] The performance tests of sensitivity, LER, and number of development defects were performed according to the following evaluation methods.

[0130] (1) Sensitivity test

[0131] The exposure dose for forming a 50 nm line and space pattern was defined as the optimal exposure dose, and the optimal exposure dose was defined as the sensitivity (mJ / cm 2 ). Sensitivity is 25mJ / cm 2 The following cases are considered to have good sensitivity, exceeding 25mJ / cm 2 The sensitivity is poor.

[0132] (2) LER test

[0133] The resist pattern was measured using a scanning electron microscope (Hitachi High-Technologies). The line width of a 1:1 line-space pattern at 50 nm was measured under a SEM (scanning electron microscope) to determine the line width variation (30 points were measured and the 3σ value was calculated), which was recorded as LER. A smaller LER value indicates less fluctuation in the line pattern and a better profile.

[0134] (3) Number of development defects

[0135] The resist film was exposed at the optimal exposure dose to form a line and space pattern with a line width of 50 nm, which was used as a defect inspection wafer. The number of defects on the defect inspection wafer was measured using a defect inspection device (KLA-Tencor "KLA2810"). Defects with a diameter of 50 μm or less were judged to originate from the resist film, and their number was calculated. If the number of defects after development was 50 or less, it was considered good, and if it exceeded 50, it was considered poor.

[0136] The sensitivity, LWR performance, and number of development defects of the resist pattern formed using the ArF immersion exposure resist composition were evaluated according to the above-mentioned methods. The results are shown in Table 3 below.

[0137] Table 3 Evaluation results of resist compositions of Examples 1 to 13 and Comparative Examples 1 to 4

[0138] Table 3 shows the evaluation results of the resist compositions of Examples 1-13 and Comparative Examples 1-4. As can be seen from Examples 1-4, the present photoacid generator can be used in combination with different host resins, acid diffusion controllers, and fluorine-containing resins. Comparison of Example 1 with Examples 5-7 shows that when R1 is a perfluoro-substituted butyl group or a trifluoromethyl group, the resist composition exhibits greater sensitivity. Comparison of Example 1 with Example 5 and Examples 8-9 shows that when X is -CO-, forming a five-membered ring of dicarboximide with its two carbon atoms on the right, Y forms a bridged ring with the two carbon atoms on the right. Compared to forming a monocyclic saturated aliphatic hydrocarbon ring, the resist film pattern exhibits better LER performance and fewer development defects.

[0139] Comparison of Examples 8 to 10 shows that when Y forms a C6-C10 bridged ring with its right carbon atoms, and X is -CO- with a dicarboximide forming a five-membered ring on both sides, the resist film pattern exhibits fewer development defects than when X is -CH2CO- with a dicarboximide forming a six-membered ring on both sides. Comparison of Examples 10 to 12 shows that when X is -CH2CO- with a dicarboximide forming a six-membered ring on both sides, and Y forms a bridged ring with its three right carbon atoms, the resist composition exhibits better sensitivity than when it forms an aromatic ring.

[0140] Comparing Examples 12-13 with Comparative Example 1 shows that when the number of carboxylic acid groups in the photoacid generator is 2 or no carboxylic acid groups, the solubility of the resist composition is poor, resulting in a high number of development defects. Comparing Examples 12-13 with Comparative Example 2 shows that if the carboxyl groups are replaced with ester groups, the sensitivity of the resist composition is poor, and the LER performance and development defects of the resist film pattern are also poor. Comparative Examples 3-4 show that when an ionic photoacid generator is used, the sensitivity of the resist composition is poor, and the LER performance and development defects of the resist film pattern are also poor. In this application, Examples 8-10 are preferred, and the sensitivity of the resist composition, the LER performance of the resist film pattern, and the development defects are all good.

[0141] Although the embodiments of the present application have been disclosed above, they are not limited to the applications listed in the description and the implementation methods. They can be fully applied to various fields suitable for the present application. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present application is not limited to the specific details and the implementation methods shown and described herein.

Claims

1. A photoacid generator, characterized in that include: The photoacid generator has a general formula represented by structural formula (1), (1) In the structural formula (1), a is 1 or 2; R1 is a perfluoro-substituted butyl group, a trifluoromethyl group, a tridecafluorohexyl group, a heptadecafluorooctyl group, a 2,2,2-trifluoroethyl group, a 1,1-difluoroethyl group, a 1,1-difluoropropyl group, a 1,1,2,2-tetrafluoropropyl group, a 3,3,3-trifluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, a norbornyltetrafluoroethyl group, adamantane-1,1,2,2-tetrafluoropropyl group, or a bicyclo[2.2.1]heptane-tetrafluoromethyl group; X is -CO-, and a dicarboximide is formed with both sides thereof to form a five-membered ring, or X is -CH2CO-, and a dicarboximide is formed with both sides thereof to form a six-membered ring; Y and the carbon atom to its right form a C6-C10 monocyclic saturated aliphatic hydrocarbon ring, a C6-C14 bridged ring, or a C6-C14 aromatic ring.

2. The photoacid generator according to claim 1, characterized in that In the structural formula (1), X is -CO-, and forms a five-membered ring dicarboximide with its two sides, and Y and its two carbon atoms on the right side together form a C6~C8 monocyclic saturated aliphatic hydrocarbon ring or a C6~C10 bridged ring, or X is -CH2CO-, and forms a six-membered ring dicarboximide with its two sides, and Y and its three carbon atoms on the right side together form a C6~C10 bridged ring, a naphthalene ring, or an anthracene ring.

3. The photoacid generator according to claim 2, characterized in that The photoacid generator is selected from one or more of the following structures: 。 4. The photoacid generator according to any one of claims 1 to 3, characterized in that In the structural formula (1), a is 1.

5. The photoacid generator according to claim 4, characterized in that The photoacid generator is selected from one or more of the following structures: 。 6. The photoacid generator according to claim 5, characterized in that In the structural formula (1), X is -CO-, and forms a five-membered ring of dicarboximide with its two sides, and Y forms a C6-C10 bridge ring with its two carbon atoms on the right.

7. The photoacid generator according to any one of claims 1 to 3, characterized in that In the structural formula (1), R1 is a perfluoro-substituted butyl group or a trifluoromethyl group.

8. A resist composition, characterized in that include: The photoacid generator (A) according to any one of claims 1 to 7, the main resin (B), the acid diffusion controller (C), the fluorine-containing resin (D) and the organic solvent (E).

9. The resist composition according to claim 8, wherein Based on 100 parts by weight of the main resin (B), the amount of the photoacid generator (A) added is 0.1 to 20 parts by weight, the amount of the acid diffusion controller (C) added is 0.1 to 5 parts by weight, and the amount of the fluorine-containing resin (D) added is 0.1 to 30 parts by weight.

10. A resist pattern forming method, characterized in that: The following steps are involved: S1, coating: coating a substrate with the resist composition according to any one of claims 8 to 9 and curing the substrate to form a photoresist film; S2, immersion exposure: After drying, light of a specific wavelength is passed through the liquid medium, and then an ArF excimer laser is used to irradiate specific areas of the photoresist film for immersion exposure; S3, development: after baking, the exposed photoresist film is developed using a developer to obtain a photoresist pattern.

Images