Cholic acid derivative resin and preparation method thereof, photoresist and application thereof, and photoetching method

Abstract

The invention provides cholic acid derivative resin and a preparation method thereof, photoresist and application thereof, and a photoetching method, and can be applied to the technical field of photoresist. According to the cholic acid derivative resin, bio-based cholic acid tert-butyl ester is used as a skeleton, and two functional groups including a diazonaphthoquinone sulfonate group and a tert-butyl ester group are introduced into molecules of the bio-based cholic acid tert-butyl ester to form a resin structure with a dual-sensitization characteristic. The photoresist composition comprises 10%-20% of the resin, 1%-5% of a photoacid generator, 1%-2% of an additive and an organic solvent. The composition shows high light transmittance in i-line photoetching, the sensitivity of the composition is lower than 130 mJ / cm, and patterning with the resolution of 64 nm can be achieved. The invention also provides a corresponding resin preparation method and a photoetching process, which are suitable for i-line projection photoetching, interference photoetching, near-field photoetching and super-resolution photoetching, and have the advantages of high resolution, environmental friendliness and good process compatibility.

Description

Technical Field

[0001] This disclosure relates to the field of photoresist technology, and more specifically to a cholic acid derivative resin and its preparation method, photoresist and its application, and photolithography method. Background Technology

[0002] Photoresist is an etch-resistant thin film material whose solubility changes under light or radiation. Due to its unique photosensitive properties, it has important applications in microelectronics manufacturing and integrated circuits. With the continuous advancement of photolithography technology, the performance requirements for photoresist materials are also increasing, especially in terms of resolution, sensitivity, and line edge roughness.

[0003] Currently, the widely used i-line photoresist system is mainly a non-chemically amplified positive photoresist composed of phenolic resin and diazonium quinone sulfonate. Its imaging principle involves the photodecomposition of the diazonium quinone groups in the exposed area, generating a carboxylic acid structure soluble in alkaline developer, thereby achieving patterning. However, this type of system suffers from low ultraviolet sensitization efficiency, resulting in lower sensitivity and resolution compared to chemically amplified photoresists.

[0004] Chemically amplified positive photoresists typically consist of a film-forming resin containing an acid-sensitive protective group, a photoacid generator, and other additives. During exposure, the photoacid generator produces acidic substances, which, in the post-baking process, catalyze a deprotection reaction in the resin, causing a change in the solubility of the exposed area. Although this type of photoresist exhibits good sensitivity, it still faces challenges such as poor control of line edge roughness, insufficient image uniformity, and the impact of acid diffusion on pattern accuracy.

[0005] Furthermore, the main resin raw materials used in existing photoresists are mostly derived from petrochemical products, and their synthesis and processing impose a certain burden on the environment, with some raw materials posing potential health risks. Meanwhile, traditional polymer-based photoresists, due to their large molecular size and tendency for molecular chains to entangle, limit their application potential in ultra-high resolution lithography.

[0006] Therefore, developing a new type of environmentally friendly photoresist material with excellent resolution and photosensitivity has become an important research direction in the field of photolithography. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the problems of traditional photoresist monomers being mostly petroleum-based, causing severe environmental pollution and significant health hazards during synthesis and application, and the low resolution of existing polymer-based photoresists, this disclosure provides a cholic acid derivative resin and its preparation method, a photoresist and its application, and a photolithography method. By simultaneously introducing two functional groups—diazonaphthoquinone sulfonate and tert-butyl ester groups—onto the molecular backbone of a bio-based cholic acid derivative resin, and employing a simple and controllable two-step substitution reaction process, a cholic acid derivative resin suitable for use as a photoresist resin is formed. This solution successfully replaces traditional petroleum-based products, avoids polymer chain entanglement problems due to its small-molecule rigid structure, and significantly improves photosensitivity through a dual sensitization mechanism. While maintaining excellent film-forming properties and substrate adhesion, it achieves ultra-high resolution patterning at 64nm and high sensitivity of 100-118mJ / cm². Its mild synthesis process and good compatibility with various advanced photolithography technologies provide a high-performance and sustainable material solution for next-generation semiconductor manufacturing.

[0009] (II) Technical Solution

[0010] To address the aforementioned technical problems, embodiments of this disclosure provide a bile acid derivative resin and its preparation method, a photoresist and its application, and a photolithography method.

[0011] According to a first aspect of this disclosure, a bile acid derivative resin is provided, the structure of which is shown below:

[0012]

[0013] Among them, R a The substituents are hydrogen-based, amide-based, or C1-C20 alkyl; the three R groups are... b The substituents are independently selected from hydroxyl, diazonaphthoquinone sulfonate group and tert-butyl ester group, and at least one R b The substituent is a diazonoquinone sulfonate group; and at least one R b The substituent is a tert-butyl ester group.

[0014] In some exemplary embodiments, the grafting rate of the diazonoquinone sulfonate group is 10% to 70%; the grafting rate of the tert-butyl ester group is 10% to 70%; and the remaining R b The substituent is a hydroxyl group.

[0015] According to a second aspect of this disclosure, a method for preparing the above-mentioned cholic acid derivative resin is provided, comprising: dissolving tert-butyl cholic acid in a first organic solvent, and carrying out a first substitution reaction with 2-diazo-1-naphthol-4-sulfonyl chloride under alkaline conditions to obtain an intermediate product; dissolving the intermediate product with ditert-butyl dicarbonate in a second organic solvent, and carrying out a second substitution reaction under the action of a catalyst to obtain the cholic acid derivative resin.

[0016] In some exemplary embodiments, the first and second organic solvents are N,N-dimethylformamide; alkaline conditions are provided by adding triethylamine to the solution; and the catalyst is 4-dimethylaminopyridine.

[0017] According to a third aspect of this disclosure, a photoresist composition is provided, comprising: a cholic acid derivative resin; an additive; and an organic solvent.

[0018] In some exemplary embodiments, based on the total mass of the photoresist composition, the mass percentages of each component are as follows: the mass percentage of the cholic acid derivative resin is 10% to 20%; the mass percentage of the additive is 1% to 2%.

[0019] In some exemplary embodiments, the photoresist composition further includes a photoacid generator, wherein the photoacid generator is present at a mass percentage of 1%-5% based on the total mass of the photoresist composition.

[0020] In some exemplary embodiments, the solvent is at least one of propylene glycol methyl ether acetate, n-butyl acetate, ethyl acetate, γ-butyrolactone, propylene glycol methyl ether, or methyl isobutyl ketone; the photoacid-generating agent is at least one of diazonium hydrochloride, diazonium sulfate, diazonium sulfonate, diazonium fluoroborate, or diazonium fluorophosphate; and the additive is at least one of surfactant or thickener.

[0021] According to a fourth aspect of this disclosure, an application of the above-described photoresist composition is provided, wherein the photoresist composition is used in i-line projection lithography, i-line interference lithography, i-line near-field lithography, or super-resolution lithography.

[0022] According to a fifth aspect of this disclosure, a photolithography method based on the above-described photoresist composition is provided, comprising: spin-coating the photoresist composition onto a substrate surface to form a photoresist film, preferably, the substrate surface having a metal film layer; pre-baking the photoresist film; patterning exposure of the pre-baked photoresist film; and developing the exposed photoresist film using a developer to form a photolithographic pattern.

[0023] (III) Beneficial Effects

[0024] As can be seen from the above technical solutions, the cholic acid derivative resin and its preparation method, the photoresist and its application, and the photolithography method provided in this disclosure have at least the following beneficial effects:

[0025] (1) Using bio-derived bile acid derivatives as the main framework of photoresist resin replaces traditional petroleum-based raw materials, thus solving the environmental pollution problem in the traditional photoresist production process from the source. As a renewable resource, bile acid derivatives meet the requirements of green chemistry and sustainable development.

[0026] (2) By using small cholic acid molecules with a rigid steroidal ring structure as the main resin, the resolution limitation caused by molecular chain entanglement of traditional polymer resins is effectively avoided. Experiments have shown that the photoresist composition disclosed herein can achieve photolithographic patterns with a linewidth of 64 nm, and the line edge roughness is low, resulting in excellent pattern quality.

[0027] (3) By simultaneously introducing diazonaphthoquinone sulfonate groups and tert-butyl ester groups onto the cholic acid backbone, the photoresist possesses both non-chemical amplification and chemical amplification dual photosensitive mechanisms. This synergistic effect enables the photoresist to exhibit high sensitivity under i-line exposure, with the optimal sensitivity reaching 100 mJ / cm², which is superior to traditional phenolic resin systems.

[0028] (4) The cholic acid derivative resin has good solubility in commonly used photoresist solvents and can form a uniform and defect-free film. The polar groups in its molecular structure enhance its adhesion to the substrate and exhibit excellent film retention during spin coating and development, meeting the requirements of industrial applications.

[0029] (5) The modification method disclosed herein can be achieved through a simple two-step substitution reaction under mild reaction conditions, without the need for special equipment. By adjusting the feed ratio of the modifier, the degree of substitution of different protecting groups can be precisely controlled, thereby optimizing the performance of the photoresist.

[0030] (6) This disclosure successfully applies bile acid derivatives to super-resolution lithography technology, including i-line projection lithography, interference lithography, near-field lithography and other lithography processes, opening up new avenues for the application of bio-based materials in the field of microelectronics manufacturing. Attached Figure Description

[0031] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0032] Figure 1 A flowchart illustrating a method for preparing a cholic acid derivative resin according to an embodiment of the present disclosure is shown schematically.

[0033] Figure 2 The image schematically shows an electron microscope (EM) image of a photoresist composition film of tert-butyl cholate derivative obtained according to Example 1 of this disclosure;

[0034] Figure 3 This schematic diagram illustrates the super-resolution photolithography effect of the tert-butyl cholate derivative obtained according to Example 1 of this disclosure as a photoresist.

[0035] Figure 4 This schematically illustrates the super-resolution photolithography effect of the phenolic resin derivative obtained according to Comparative Example 1 as a photoresist; and

[0036] Figure 5 The diagram illustrates the super-resolution lithography effect of the poly(p-hydroxystyrene) derivative obtained according to Comparative Example 2 as a photoresist. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0038] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0039] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0040] This disclosure provides a cholic acid derivative resin, the structure of which is shown below:

[0041]

[0042] Wherein, the Ra substituent is a hydrogen group, an amide group, or a C1-C20 alkyl group; the three R groups are hydroxyl groups, amide groups, or C1-C20 alkyl groups. b The substituents are independently selected from hydroxyl, diazonaphthoquinone sulfonate group and tert-butyl ester group, and at least one R b The substituent is a diazonoquinone sulfonate group; and at least one R b The substituent is a tert-butyl ester group.

[0043] Preferably, tert-butyl cholate is selected as the main resin for the study. Some of the hydroxyl groups in tert-butyl cholate are replaced by diazonoquinone sulfonate and tert-butyl ester groups to obtain cholic acid derivatives. The structural formula of the cholic acid derivatives is as follows:

[0044]

[0045] The three Rb substituents are independent of each other, and the Rb substituents are hydroxyl (-OH) and diazonoquinone sulfonate (-OH). ) or tert-butyl ester group ( ).

[0046] Preferably, the grafting rate of the diazonoquinone sulfonate group is 10% to 70%; the grafting rate of the tert-butyl ester group is 10% to 70%; and the remaining R b The substituent is a hydroxyl group.

[0047] In the embodiments of this disclosure, tert-butyl cholate, as a bio-based material, possesses a unique rigid molecular backbone and modifiable active groups. These structural characteristics enable its derivatives to exhibit excellent photolithographic performance as photoresist materials, including high sensitivity, high resolution, and good etching resistance. Compared to linear polymer materials (such as PHS), tert-butyl cholate derivatives, as small-molecule resins, have a low tendency for molecular chain entanglement, which helps to improve the resolution and edge sharpness of patterns. Simultaneously, this derivative, through structural design, possesses both chemical amplification and non-chemical amplification mechanisms, exhibiting dual sensitivity and enabling efficient patterning under different exposure conditions.

[0048] According to a second aspect of this disclosure, a method for preparing the above-mentioned cholic acid derivative resin is provided, comprising steps S1-S2, see [link to relevant documentation]. Figure 1 .

[0049] In step S1, tert-butyl cholate is dissolved in a first organic solvent and reacted with 2-diazo-1-naphthol-4-sulfonyl chloride under alkaline conditions. The first substitution reaction is carried out to obtain the intermediate product.

[0050] In the embodiments of this disclosure, the first organic solvent is N,N-dimethylformamide, the alkaline conditions are provided by adding triethylamine to the solution, and the reaction equation for the first substitution reaction is:

[0051]

[0052] Step S1 is a sulfonation nucleophilic substitution reaction. The hydroxyl group (-OH) in the tert-butyl cholate molecule acts as a nucleophile, attacking the partially positively charged sulfur atom in 2-diazo-1-naphthol-4-sulfonyl chloride. Triethylamine acts as an acid-binding agent, combining with the reaction byproduct hydrogen chloride to form triethylamine hydrochloride, driving the reaction towards the product. Ultimately, a sulfonate bond with photosensitizing properties is formed (…). A successful study introduced the diazonaphthoquinone (DNQ) photosensitive group onto the bile acid backbone. DNQ groups were directionally grafted onto the bile acid backbone via sulfonation, endowing the material with non-chemically amplified photolithographic properties and laying the molecular foundation for subsequent dual-sensitization functionality. A mild reaction system using DMF as solvent and triethylamine as base avoided the destruction of the rigid bile acid backbone by strong acid and base conditions, ensuring the structural integrity of the product. Simultaneously, the reaction selectively modified hydroxyl groups without affecting existing sensitive structures such as ester groups and steroid rings in the bile acid molecule, maintaining the overall stability of the material.

[0053] In step S2, the intermediate product is reacted with di-tert-butyl dicarbonate ( The cholic acid derivative resin is dissolved in a second organic solvent and undergoes a second substitution reaction under the action of a catalyst.

[0054] In the embodiments of this disclosure, the second organic solvent is N,N-dimethylformamide; the catalyst is 4-dimethylaminopyridine; and the reaction equation for the second substitution reaction is:

[0055]

[0056] Step S2 is the BOC protection reaction, which belongs to the nucleophilic substitution mechanism. Under the catalysis of 4-dimethylaminopyridine (DMAP), the remaining hydroxyl oxygen atom in the intermediate molecule nucleophilically attacks the carbonyl carbon atom of di-tert-butyl dicarbonate (BOC anhydride), forming an unstable tetrahedral intermediate. This intermediate then decomposes to produce carbon dioxide and tert-butoxy anions, ultimately completing the introduction of the BOC protecting group and generating a cholic acid derivative resin containing the tert-butyl ester group. DMAP, as a highly efficient acylation catalyst, significantly improves the rate and efficiency of the BOC protection reaction by forming a more active acylpyridinium intermediate. The highly efficient catalytic system successfully introduces the tert-butyl ester protecting group, which, together with the previously grafted DNQ group, constructs a dual-sensitization function.

[0057] In the embodiments of this disclosure, tert-butyl cholate is functionalized using a specific modifier, selectively replacing the hydrogen atoms in the hydroxyl groups of its molecule, thereby introducing two types of protecting groups—tert-butyl ester groups and sulfonyl ester groups—into the side chain. This structural design allows the resulting tert-butyl cholate derivative to simultaneously integrate the response mechanisms of non-chemically amplified DNQ and chemically amplified photoresists, exhibiting dual-sensitization characteristics. This derivative exhibits good light transmittance in the i-line band, and photoresists prepared using it as a base resin demonstrate excellent photolithographic performance. Furthermore, the introduced tert-butyl ester polar groups effectively enhance the adhesion between the photoresist and the substrate, while the inherent multi-six-membered ring structure of the cholic acid backbone endows the material with high molecular rigidity and stability, resulting in good etching resistance after film formation.

[0058] According to a third aspect of this disclosure, a photoresist composition is provided, comprising: a cholic acid derivative resin; an additive; and an organic solvent.

[0059] In some exemplary embodiments, based on the total mass of the photoresist composition, the mass percentage of the cholic acid derivative resin is 10% to 20%; the mass percentage of the additives is 1% to 2%; and the mass percentage of the organic solvent is 78% to 89%.

[0060] Optionally, the photoresist composition further includes a photoacid generator, wherein the photoacid generator is at a mass percentage of 1%-5% based on the total mass of the photoresist composition, and the mass percentage of the organic solvent is adjusted to 73%-88% when the photoacid generator is included.

[0061] Optionally, the solvent is at least one of propylene glycol methyl ether acetate, n-butyl acetate, ethyl acetate, γ-butyrolactone, propylene glycol methyl ether, or methyl isobutyl ketone; the photoacid-generating agent is at least one of diazonium hydrochloride, diazonium sulfate, diazonium sulfonate, diazonium fluoroborate, or diazonium fluorophosphate; and the additive is at least one of surfactant or thickener.

[0062] The photoresist composition according to embodiments of this disclosure uses a bile acid derivative resin as the core functional component. High-performance patterning is achieved through the synergistic effect of the bile acid derivative resin (10-20%), a photoacid generator (1-5%), additives (1-2%), and organic solvents. Its mechanism of action is based on a dual photosensitive system formed by the photodecomposition reaction of the diazonaphthoquinone sulfonate group and the acid-catalyzed deprotection reaction of the tert-butyl ester group in the resin. This system generates dissolution contrast during exposure and enhances response sensitivity through a chemical amplification effect. Simultaneously, the rigid steroidal ring structure in the resin provides skeletal support, while the protecting groups regulate molecular polarity to achieve dissolution differences between exposed and unexposed areas in the alkaline developer. Surfactants optimize interfacial tension, and tackifiers enhance interfacial adhesion. Furthermore, the acidic substances generated by the photoacid generator during exposure diffuse to the resin molecules during subsequent baking, catalyzing the decomposition reaction of the tert-butyl ester group and achieving a chemical amplification effect.

[0063] The sensitivity of the tert-butyl cholate photoresist composition according to embodiments of this disclosure is less than 130 mJ / cm. 2 It can be used for super-resolution lithography to expose patterns at a resolution of 64 nm. Furthermore, it can be used for i-line projection lithography, i-line interference lithography, i-line near-field lithography, or super-resolution lithography.

[0064] The photolithography method based on the above-mentioned photoresist composition includes: spin-coating the photoresist composition onto a substrate surface to form a photoresist film, wherein the substrate surface may have a metal film layer; pre-baking the photoresist film; patterning exposure of the pre-baked photoresist film; and developing the exposed photoresist film using a developer to form a photolithographic pattern. This process is simple to operate, operates under mild conditions, has good compatibility with existing semiconductor manufacturing equipment, and can obtain photolithographic patterns with clear lines and complete morphology on wafers, meeting the high requirements of ultra-resolution photolithography for pattern accuracy and process stability.

[0065] For example, the photoresist composition uses a tert-butyl cholate derivative as the main resin, and its addition amount is 10% to 20% of the total weight of the composition. During preparation, the components are fully dispersed and dissolved, and then filtered to obtain a composition that can be used in the photolithography process.

[0066] The exposure process includes the following steps:

[0067] (1) Spin coating: The photoresist composition is uniformly coated on a substrate such as a wafer surface, and the substrate is rotated at a speed of 1000-3000 rpm for 30-60 seconds to form a film. The film thickness can be controlled by adjusting the speed or the concentration of the composition. Preferably, the substrate surface has a metal film layer such as gold, silver, or aluminum.

[0068] (2) Pre-baking: The coated wafer is baked on a hot plate at 100°C for 2 minutes;

[0069] (3) Exposure: Place the pre-baked wafer into the exposure system, align it with the mask, and expose it according to the set dose;

[0070] (4) Development: Immerse the exposed wafer in a 2.38% (w / w) tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds;

[0071] (5) Fixing: After development, immediately transfer to deionized water for fixing to remove residual developer.

[0072] Through the above process, a complete photolithographic pattern can be obtained on the wafer.

[0073] Based on the above-mentioned photolithography method using photoresist compositions, by optimizing the process parameters of spin coating, pre-baking, exposure, development, and fixing, high compatibility with existing semiconductor equipment is achieved. Film thickness can be precisely controlled under conventional production conditions to form a uniform and defect-free film. This method utilizes the dual-sensitization characteristics of photoresist, and with the synergistic effect of 2.38% TMAH developer and deionized water fixing, a 64 nm ultra-high resolution pattern was successfully prepared. The pattern has clear lines and low edge roughness. At the same time, the entire process has the advantages of simple operation, high stability, and environmental friendliness, providing a reliable solution for the industrial application of ultra-resolution photolithography technology.

[0074] Example 1:

[0075] The cholic acid derivative resin in this embodiment is a tert-butyl cholic acid derivative containing 2-diazo-1-phenolnaphth-4-sulfonyl chloride and BOC group substitution, with the following structural formula:

[0076]

[0077] The synthesis method of this tert-butyl cholate derivative is as follows: 1.858 g of tert-butyl cholate was dissolved in 50 mL of N,N-dimethylformamide (DMF). The reaction system was then placed in an ice bath. Triethylamine (0.808 g) was slowly added to the reaction system over 30 min. Subsequently, 2-diazo-1-phenolnaphth-5-sulfonyl chloride (2.15 g) was dissolved in 30 mL of DMF and added dropwise to the reaction system using a constant pressure dropping funnel over 30 min. The reaction system was then heated to 25 °C and reacted for 24 hours. After the reaction was completed, the reaction mixture was added to a large amount of water to precipitate the solid. The solid was filtered off and washed with pure water at least three times. The solid was then dried under vacuum at 50 °C for 24 hours to obtain the intermediate product DN00. 1.5 g of DN00 was added to 50 mL of DMF. The mixture was placed in an ice bath and stirred until the DN00 was completely dissolved. Then, 0.05 g of 4-dimethylaminopyrimidine was added and stirred until homogeneous. A certain amount of di-tert-butyl dicarbonate was then slowly added. The entire system was reacted at room temperature for 24 h. After the reaction was complete, the mixture was added to a large amount of water to precipitate a solid product. The solid was obtained by filtration and then washed with pure water. The solid sample was dried at 50 °C and used for subsequent exposure experiments. The grafting ratio of the solid sample was calculated to be DNQ:BOC = 1:2 (where the grafting rate of DNQ was 33% and the grafting rate of BOC was 66%).

[0078] Example 2:

[0079] The cholic acid derivative resin in this embodiment is a tert-butyl cholic acid derivative containing 2-diazo-1-phenolnaphth-4-sulfonyl chloride and BOC group substitution, as follows:

[0080]

[0081] The synthesis method of this tert-butyl cholate derivative is as follows: 1.858 g of tert-butyl cholate was dissolved in 50 mL of N,N-dimethylformamide (DMF). The reaction system was then placed in an ice bath. Triethylamine (0.808 g) was slowly added to the reaction system over 30 min. Subsequently, 2-diazo-1-phenolnaphth-5-sulfonyl chloride (2.15 g) was dissolved in 30 mL of DMF and added dropwise to the reaction system using a constant pressure dropping funnel over 30 min. The reaction system was then heated to 25 °C and reacted for 24 hours. After the reaction was completed, the reaction mixture was added to a large amount of water to precipitate the solid. The solid was filtered off and washed with pure water at least three times. The solid was then dried under vacuum at 50 °C for 24 hours to obtain the intermediate product DN01. 1.5 g of DN01 was added to 50 mL of DMF. The mixture was placed in an ice bath and stirred until DN01 was completely dissolved. Then, 0.02 g of 4-dimethylaminopyrimidine was added and stirred until homogeneous. A certain amount of di-tert-butyl dicarbonate was then slowly added. The entire system was reacted at room temperature for 24 h. After the reaction was complete, the mixture was added to a large amount of water to precipitate a solid product. The solid was obtained by filtration and then washed with pure water. The solid sample was dried at 50 °C and used for subsequent exposure experiments. The grafting ratio of the solid sample was calculated to be DNQ:BOC = 1:1 (where the grafting rate of DNQ was 33% and the grafting rate of BOC was 33%).

[0082] Example 3:

[0083] The cholic acid derivative resin in this embodiment is a tert-butyl cholic acid derivative containing 2-diazo-1-phenolnaphth-4-sulfonyl chloride and BOC group substitution, as shown below:

[0084]

[0085] The synthesis method of this tert-butyl cholate derivative is as follows: 1.858 g of tert-butyl cholate was dissolved in 50 mL of N,N-dimethylformamide (DMF). The reaction system was then placed in an ice bath. Triethylamine (1.7 g) was slowly added to the reaction system over 30 min. Subsequently, 4.15 g of 2-diazo-1-phenolnaphth-5-sulfonyl chloride was dissolved in 30 mL of DMF and added dropwise to the reaction system using a constant pressure dropping funnel over 30 min. The reaction system was then heated to 25 °C and reacted for 24 hours. After the reaction was completed, the reaction mixture was added to a large amount of water to precipitate the solid. The solid was filtered off and washed with pure water at least three times. The solid was then dried under vacuum at 50 °C for 24 hours to obtain the intermediate product DN02. 1.5 g of DN02 was added to 50 mL of DMF. The mixture was placed in an ice bath and stirred until the DN02 was completely dissolved. Then, 0.02 g of 4-dimethylaminopyrimidine was added and stirred until homogeneous. A certain amount of di-tert-butyl dicarbonate was then slowly added. The entire system was reacted at room temperature for 24 h. After the reaction was complete, the mixture was added to a large amount of water to precipitate a solid product. The solid was obtained by filtration and then washed with pure water. The solid sample was dried at 50 °C and used for subsequent exposure experiments. The grafting ratio of the solid sample was calculated to be DNQ:BOC = 2:1 (where the grafting rate of DNQ was 67% and the grafting rate of BOC was 33%).

[0086] Comparative Example 1:

[0087] The resin used in this comparative example is a phenolic resin containing 2-diazo-1-phenolnaphth-4-sulfonyl chloride and BOC group substitution, and its specific structure is shown below:

[0088]

[0089] Wherein, R1 is a hydroxyl (-OH) group and a diazonoquinone sulfonate group ( ) or tert-butyl ester group ( ).

[0090] The resin was synthesized as follows: 2.8 g of phenolic resin was dissolved in 50 mL of dimethylformamide. The reaction system was then placed in an ice bath. Triethylamine (1.06 g) was slowly added to the reaction system. Then, 2.5 g of 2-diazo-1-phenolnaphth-4-sulfonyl chloride (2.5 g) was dissolved in 30 mL of dimethylformamide and added dropwise to the reaction system using a constant-pressure dropping funnel over half an hour. The system was then heated to 25 °C and reacted for 24 hours. After the reaction was complete, the reaction mixture was added to a large amount of water to precipitate the solid. The solid was filtered off, washed with water at least three times, and dried under vacuum at 50 °C for 24 hours to obtain the solid intermediate DN03. 2 g of DN03 was added to 50 mL of DMF. The mixture was placed in an ice bath and stirred until DN03 was completely dissolved. Then, 0.1 g of 4-dimethylaminopyrimidine was added and stirred until homogeneous. Finally, a certain amount of di-tert-butyl dicarbonate was slowly added. The entire system was reacted at room temperature for 24 hours. After the reaction was complete, the mixture was added to a large amount of water to precipitate the solid product. The solid was then filtered and washed with pure water. The grafting ratio of the solid sample was calculated to be DNQ:BOC = 1:2 (where the grafting ratio of DNQ was 33% and the grafting ratio of BOC was 67%).

[0091] Comparative Example 2:

[0092] The resin used in this comparative example is a poly(p-hydroxystyrene) resin containing 2-diazo-1-phenolnaphth-4-sulfonyl chloride and Boc group substitution, and its specific structure is shown below:

[0093]

[0094] Wherein, R2 is a hydroxyl (-OH) group and a diazonoquinone sulfonate group ( ) or tert-butyl ester group ( ).

[0095] The resin was synthesized as follows: Poly(p-hydroxystyrene) (PDI: 1.1, 3.4 g) was dissolved in 50 mL of dimethylformamide. The reaction system was then placed in an ice bath. Triethylamine (1.86 g) was slowly added to the reaction system. Then, 2-diazo-1-phenolnaphth-4-sulfonyl chloride (2.87 g) was dissolved in 30 mL of dimethylformamide and added dropwise to the reaction system using a constant pressure dropping funnel over half an hour. The system was then heated to 25 °C and reacted for 24 hours. After the reaction was complete, the reaction mixture was added to a large amount of water to precipitate the solid. The solid was filtered off, washed with water at least three times, and dried under vacuum at 50 °C for 24 hours to obtain the solid intermediate DN04. DN04 (2.8 g) was added to 50 mL of DMF. The mixture was placed in an ice bath and stirred until DN04 was completely dissolved. Then, 4-dimethylaminopyrimidine (0.8 g) was added and stirred until homogeneous. Finally, a certain amount of di-tert-butyl dicarbonate was slowly added. The entire system was reacted at room temperature for 24 hours. After the reaction was complete, the mixture was added to a large amount of water to precipitate the solid product. The solid was obtained by filtration and then washed with pure water. The grafting ratio of the solid sample was calculated to be DNQ:BOC = 1:2 (where the grafting rate of DNQ was 33% and the grafting rate of BOC was 67%).

[0096] Example 4: Film Retention Rate Test

[0097] A certain weight of the resins synthesized in Examples 1, 2, and 3 and Comparative Examples 1 and 2 was dissolved in 3 mL of photoresist solvent. Then, a photoinitiator and additives were added, and the mixture was thoroughly shaken to dissolve. The solution was then filtered through a 0.22-micron needle filter to obtain the photoresist composition.

[0098] Table 1. Photoresist compositions formulated with resins synthesized in Examples 1-3 and Comparative Examples 1-2

[0099]

[0100] The photoresist composition was spin-coated onto the surface of a wafer with a metal film layer (coated with a silver film layer), and the film-forming properties and film retention of the photoresist film layer were measured. As shown in Table 2, the photoresist compositions prepared in each embodiment did not have problems with film retention and film-forming properties.

[0101] Table 2. Film retention rate of the resins synthesized in Examples 1-3 and Comparative Examples 1-2 in different solvents

[0102]

[0103] The photoresist compositions prepared in Examples 1, 2, and 3, as well as Comparative Examples 1 and 2, showed no problems in film formation and film retention on wafers, indicating that the resins in the above experimental examples all have good film properties.

[0104] Example 5: Film-forming property experiment

[0105] The photoresist composition prepared in the above experiment was spin-coated onto a silicon wafer at a certain rotation speed, and then baked on a hot plate at 100°C for 2 min. After baking, the surface quality of the film was observed with an electron microscope, and the statistical results of film formation based on the surface quality are shown in Table 3.

[0106] Table 3. Film-forming properties of the resins synthesized in Examples 1-3 and Comparative Examples 1-2

[0107]

[0108] The photoresist compositions prepared in Examples 1, 2, and 3, as well as Comparative Examples 1 and 2, all exhibited no problems in film formation. The film layer coated on a wafer using the photoresist composition prepared with PGMEA in Example 1 was observed using an electron microscope, and... Figure 2 The film surface shown has no obvious pinholes or defects and is uniform and smooth, meeting the requirements for photoresist exposure.

[0109] Example 6: Sensitivity Test

[0110] The prepared photoresist composition was uniformly coated onto a wafer with a deposited silver film to prepare sample substrates. After baking at 100°C for 2 min, super-resolution exposure was performed at the i-line wavelength (exposure area: a circle with a diameter of 1 cm). After exposure, the substrate was placed on a hot plate at 120°C and baked for 2 min. After natural cooling, the sample was immersed in 2.83% tetramethylammonium hydroxide (TMAH) standard developer for 60 s, then rinsed with ultrapure water and dried with nitrogen to obtain the photolithographic pattern. The sensitivity test results of Examples 1-3 and Comparative Examples 1-2 are shown in Table 4.

[0111] Table 4. Sensitivity test results of Examples 1-3 and Comparative Examples 1-2

[0112]

[0113] The sensitivities of implementations 1, 2, and 3 are all less than 130 mJ / cm. 2 Among them, Example 1 exhibits the best sensitivity, reaching 100 mJ / cm. 2 The sensitivity of Comparative Examples 1 and 2 was slightly lower. This indicates that the photoresist composition based on tert-butyl cholate derivatives exhibits better photolithographic performance compared to the other two linear resins.

[0114] Example 7: Resolution Experiment

[0115] The materials prepared in Examples 1, 2, and 3, and Comparative Examples 1 and 2, were dissolved in PGMEA. After complete dissolution, the solution was filtered through a 0.22 μm pore size filter to obtain a photoresist composition. This composition was spin-coated onto an SP photoresist layer, baked at 100°C for 2 min, exposed, and then baked at 100°C for 1 min. Development was performed using a 2.38% tetramethylammonium hydroxide solution for 30 s, followed by fixing with deionized water for 15 s. After drying, the pattern was examined using a scanning electron microscope, yielding a 64 nm resolution pattern. The exposure pattern quality of Examples 1-3 and Comparative Examples 1-2 was compared.

[0116] Table 5. Exposure pattern quality of Examples 1-3 and Comparative Examples 1-2

[0117]

[0118] The exposure pattern of Experiment Example 1 is as follows: Figure 3 As shown, scanning electron microscopy revealed that Experimental Example 1 yielded a pattern with a resolution of 64 nm and excellent pattern quality. In contrast, Comparative Examples 1 and 2 showed that neither photoresist composition possessed the ability to form a high-resolution 64 nm pattern; at 64 nm resolution, the lines adhered together and could not be attached to the substrate (e.g., lines were stuck together). Figure 4 , 5 (As shown). The photoresist based on Example 1 can achieve good patterns at a resolution of 64nm, while taking into account both sensitivity and resolution performance, proving the feasibility of this embodiment.

[0119] Those skilled in the art will understand that the features described in the various embodiments of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

Claims

1. A cholic acid derivative resin, characterized in that, The structure of the cholic acid derivative resin is shown below: Wherein, the R a The substituents are hydrogen groups, amide groups, or C1-C20 alkyl groups; The three Rs b The substituents are independently selected from hydroxyl, diazonaphthoquinone sulfonate group and tert-butyl ester group, and at least one of the R groups is selected from hydroxyl, diazonaphthoquinone sulfonate group and tert-butyl ester group. b The substituent is the diazonaphthoquinone sulfonate group; and at least one of the R groups. b The substituent is the tert-butyl ester group.

2. The cholic acid derivative resin according to claim 1, characterized in that, The grafting rate of the diazonaphthoquinone sulfonate group is 10% to 70%; The grafting rate of the tert-butyl ester group is 10% to 70%; and The remaining R b The substituent is a hydroxyl group.

3. A method for preparing the cholic acid derivative resin according to claim 1 or 2, characterized in that, include: tert-butyl cholate was dissolved in a first organic solvent and reacted with 2-diazo-1-naphthol-4-sulfonyl chloride under alkaline conditions to undergo a first substitution reaction, yielding an intermediate product. The intermediate product and di-tert-butyl dicarbonate were dissolved in a second organic solvent, and a second substitution reaction was carried out under the action of a catalyst to obtain the cholic acid derivative resin.

4. The preparation method according to claim 3, characterized in that, The first organic solvent and the second organic solvent are N,N-dimethylformamide; The alkaline conditions are provided by adding triethylamine to the solution; The catalyst is 4-dimethylaminopyridine.

5. A photoresist composition, characterized in that, include: The cholic acid derivative resin as described in any one of claims 1 to 2; additive; as well as Organic solvents.

6. The photoresist composition according to claim 5, characterized in that, Based on the total mass of the photoresist composition, the mass percentages of each component are as follows: The mass percentage of the cholic acid derivative resin is 10% to 20%; The additive is 1% to 2% by mass.

7. The photoresist composition according to claim 5 or 6, characterized in that, The photoresist composition further includes a photoacid generator, wherein the photoacid generator has a mass percentage of 1%-5% based on the total mass of the photoresist composition.

8. The photoresist composition according to claim 7, characterized in that, The solvent is at least one of propylene glycol methyl ether acetate, n-butyl acetate, ethyl acetate, γ-butyrolactone, propylene glycol methyl ether, or methyl isobutyl ketone. The photo-induced acid-producing agent is at least one of diazonium hydrochloride, diazonium sulfate, diazonium sulfonate, diazonium fluoroborate, or diazonium fluorophosphate. The additive is at least one of a surfactant or a thickener.

9. An application of the photoresist composition according to any one of claims 5-8, characterized in that, The photoresist composition is used for i-line projection lithography, i-line interference lithography, i-line near-field lithography, or super-resolution lithography.

10. A photolithography method based on the photoresist composition according to any one of claims 5-8, characterized in that, include: The photoresist composition is spin-coated onto the surface of a substrate to form a photoresist film, wherein the surface of the substrate preferably has a metal film layer; The photoresist film is pre-baked. Patterned exposure is performed on the photoresist film after pre-baking; The exposed photoresist film is developed using a developer to form a photolithographic pattern.

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