Deep ultraviolet photoresist as well as preparation method and application thereof

Abstract

The invention discloses deep ultraviolet photoresist as well as a preparation method and application thereof, and relates to the technical field of deep ultraviolet photoresist. The deep ultraviolet photoresist is prepared from the following components in parts by mass: 15 to 25 parts of matrix resin, 1 to 5 parts of a photosensitizer, 0.5 to 3 parts of a photoacid generator, 2 to 8 parts of a cross-linking agent, 0.1 to 1 part of a surfactant and 60 to 80 parts of an organic solvent. By optimizing the structure of the photosensitizer, the light absorption capacity of the photoresist in a deep ultraviolet band is enhanced, the sensitivity of the photoresist is effectively improved, the exposure time is shortened, and the production efficiency is improved. The photosensitizer and the photoacid generator act synergistically, so that the acid diffusion range is accurately controlled, the resolution is prevented from being reduced while the sensitivity is improved, and finer patterning is realized.

Description

Technical Field

[0001] This invention relates to the field of deep ultraviolet photoresist technology, specifically to a deep ultraviolet photoresist, its preparation method, and its application. Background Technology

[0002] In modern semiconductor manufacturing processes, photolithography is a crucial step, and photoresist (also known as photoresist) is the core material for achieving high-precision pattern transfer. As semiconductor devices continue to evolve towards smaller sizes and higher integration, deep ultraviolet (DUV) photoresist has become the focus of the industry.

[0003] Traditional photoresists, such as g-line (436nm) and i-line (365nm) photoresists, are increasingly inadequate for semiconductor manufacturing applications with extremely high linewidth requirements, such as advanced logic chips and dynamic random access memory (DRAM), due to their resolution limitations. Deep ultraviolet photoresists, with their shorter wavelengths of 248nm and 193nm, can achieve higher resolution patterning.

[0004] However, there are many challenges currently facing deep ultraviolet (DUV) photoresists on the market. On the one hand, some photoresist components have high absorption of DUV light, affecting exposure efficiency and image quality. On the other hand, in high-resolution imaging, it is difficult to balance the sensitivity of the photoresist with performance characteristics such as resolution and contrast. For example, while high-sensitivity photoresists can reduce exposure time, they may be accompanied by a decrease in resolution, affecting the performance of the final device.

[0005] Furthermore, the development and etching resistance of the photoresist, as well as its compatibility with subsequent processes, need to be optimized. During development, the photoresist must precisely remove the exposed areas while maintaining the integrity of the unexposed areas. During etching, the photoresist must provide sufficient etching resistance to ensure accurate transfer of the pattern to the underlying material.

[0006] Therefore, although deep ultraviolet photoresists have broad application prospects in the semiconductor manufacturing field, they still face many problems that need to be solved in terms of material properties and process adaptability, and require continuous research and innovation to meet the growing semiconductor manufacturing demand. Summary of the Invention

[0007] The purpose of this invention is to address the problems existing in the prior art by providing a high-resolution, high-sensitivity, and stable deep ultraviolet photoresist. By optimizing the composition and preparation process, it overcomes the shortcomings of existing photoresists, such as the difficulty in achieving both resolution and sensitivity at deep ultraviolet wavelengths and poor development and etching performance, thereby meeting the higher requirements of advanced semiconductor manufacturing for photoresist materials.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: a deep ultraviolet photoresist, comprising the following components by weight: main resin: 15-25 parts, photosensitizer: 1-5 parts, photoacidifier: 0.5-3 parts, crosslinking agent: 2-8 parts, surfactant: 0.1-1 parts, organic solvent: 60-80 parts; The photosensitizer has the structure shown in Formula 1: Formula 1; R1 is selected from: methyl, tert-butyl, cyano, nitro.

[0009] Furthermore, the main resin is a phenolic resin.

[0010] Furthermore, the photosensitizer is any one of the compounds shown in the following structures:

[0011] .

[0012] Furthermore, the photoacid is a diaryliodomonium salt.

[0013] Furthermore, the crosslinking agent is hexamethoxymethylmelamine.

[0014] Furthermore, the surfactant is sodium dodecyl sulfate.

[0015] Furthermore, the organic solvent is propylene glycol methyl ether acetate.

[0016] A method for preparing a deep ultraviolet photoresist includes the following steps: S1. Under light-protected conditions, dissolve the main resin in an organic solvent, stirring at 40-60°C for 1-2 hours; S2. Add photosensitizer, photoacid generator and crosslinking agent, and continue stirring for 0.5-1 hour; S3. Add surfactant, mix evenly, and filter to obtain the deep ultraviolet photoresist.

[0017] Furthermore, S1 is performed under a nitrogen atmosphere.

[0018] Application of a deep ultraviolet photoresist in semiconductor photolithography.

[0019] Furthermore, the application of the deep ultraviolet photoresist in semiconductor photolithography is used for patterned transfer processing in 248nm or 193nm deep ultraviolet photolithography technology.

[0020] Furthermore, the photoresist is coated on a silicon wafer or gallium nitride substrate and then pre-baked, exposed, post-baked, and developed to form micro- and nano-scale patterns.

[0021] Furthermore, the formed pattern has a linewidth resolution of ≤100nm, which is suitable for metal interconnect layer or transistor gate patterning processes in integrated circuit manufacturing.

[0022] The photosensitizer described in this invention absorbs 180-290nm ultraviolet light, enhancing the sensitivity of the photoresist (i.e., reducing exposure time). Simultaneously, through structural optimization (such as the selection of the R1 group), it balances resolution, avoiding the problem of "high sensitivity leading to decreased resolution." The photosensitizer and photoacid generator are independent components. In chemically amplified photoresists, the photosensitizer typically acts as a light absorber, catalyzing the photoacid generator to produce acid after absorbing photons. This acid further initiates a crosslinking reaction between the crosslinking agent and the host resin. This process leads to chemical changes in the resin in the exposed area during the exposure stage, thereby achieving micro / nanoscale pattern transfer.

[0023] The deep ultraviolet photoresist described in this invention employs a specially structured photosensitizer. Its high absorption characteristics in the deep ultraviolet band (180-290nm) significantly enhance sensitivity, while polar groups such as cyano / nitro groups precisely control the acid diffusion range by regulating molecular polarity, thus balancing the conflict between sensitivity and resolution from the source. This photosensitizer, in synergy with a photoacid generator, triggers a "chemical amplification effect"—single-photon excitation catalyzes the generation of multiple rounds of acids, producing H... + A highly efficient catalytic crosslinking agent undergoes dehydration condensation with phenolic resin to form a dense crosslinked network. This cascade reaction rapidly solidifies the exposed area into an insoluble structure (improving development contrast), while the unexposed area remains soluble (ensuring clear edge sharpness of patterns ≤100nm). Simultaneously, the phenolic resin framework imparts high etching resistance to the system. Among the auxiliary components, sodium dodecyl sulfate optimizes substrate wettability and enhances the difference in interfacial tension during development, while propylene glycol methyl ether acetate solvent ensures uniform component dispersion and defect-free film formation. Combined with nitrogen-protected light-shielded dissolution, stepwise feeding, and temperature-controlled stirring processes, the final result is an exposure time reduction of over 30% and a resolution of 100nm (meeting the requirements for metal interconnect / gate patterning). Furthermore, batch-to-batch stability is ensured through component purity control, fully adapting to the high-precision patterning requirements of deep ultraviolet lithography.

[0024] Compared with the prior art, the beneficial effects of the present invention are: 1. Significantly improved sensitivity: By optimizing the photosensitizer structure, the photoresist's light absorption capacity in the deep ultraviolet band is enhanced, effectively improving the photoresist's sensitivity, reducing exposure time, and increasing production efficiency.

[0025] 2. Significantly improved resolution: The photosensitizer and photoacid agent work synergistically to precisely control the acid diffusion range, improving sensitivity while avoiding a decrease in resolution, thus achieving more refined patterning.

[0026] 3. Improved development contrast and etching resistance: The exposed area cures rapidly to form an insoluble structure, while the unexposed area remains soluble, thus improving development contrast; the phenolic resin framework enhances the etching resistance of the photoresist, ensuring accurate pattern transfer. Attached Figure Description

[0027] Figure 1 This is the nuclear magnetic resonance (HNMR) image of photosensitizer 1 described in this invention. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Synthesis example 1 Synthesis of photosensitizer 1: ; Step 1: Under a nitrogen atmosphere, add 20g of raw material 1, 23.89g of raw material 2, 24.56g of anhydrous potassium carbonate, and 280g of a mixed solution of toluene, ethanol, and water (volume ratio 2:1:1) to the reaction system sequentially. Stir until homogeneous and purge with nitrogen twice. Under nitrogen protection, add 3.08g of tetra(triphenylphosphine)palladium to the reaction system, purge with nitrogen twice again, and heat to 95°C and reflux for 10 hours. Turn off the heating, cool to room temperature, and allow to stand for separation. Extract the aqueous phase twice with ethyl acetate and combine the organic phases. Dry the organic phase with anhydrous magnesium sulfate, filter, evaporate to dryness, and perform column chromatography using a mixture of petroleum ether and ethyl acetate as eluent. Evaporate to dryness to obtain 22.64g of intermediate 1.

[0030] Step 2: Under a nitrogen atmosphere, add 22.64 g of intermediate 1, 18.27 g of starting material 3, 19.29 g of potassium carbonate, 0.47 g of palladium acetate, 0.7 g of tri-tert-butylphosphine, and 220 g of toluene to the reaction system. Stir until homogeneous, heat to 110 °C, and reflux for 12 h. After the reaction is complete, lower the temperature slightly and filter using diatomaceous earth. After cooling the filtrate to room temperature, wash three times with water, retain the organic phase, and then extract the aqueous phase with ethyl acetate. Combine the organic phases, dry with anhydrous magnesium sulfate, filter, evaporate to dryness, and perform column chromatography using a mixture of petroleum ether and ethyl acetate as eluent. Evaporate to dryness to obtain 25.96 g of photosensitizer 1.

[0031] Product structure identification: MS[MS+H] of intermediate 1 + 325; MS [MS+H] of photosensitizer 1+ :462; The nuclear magnetic resonance (HNMR) of photosensitizer 1 is as follows: δ 8.14-8.07 (m, 1H), 7.97-7.90 (m, 1H), 7.86 (d, 1H), 7.83-7.75 (m, 2H), 7.70 (dd, 1H), 7.47 (dd, 1H), 7.05 (dd, 1H), 2.49 (s, 3H).

[0032] Synthesis Example 2-Synthesis Example 4 In Synthesis Examples 2-4, photosensitizers 2 and 4 were synthesized sequentially, following the same synthesis method as in Synthesis Example 1, except that raw material 1 was replaced; the rest remained the same as in Synthesis Example 1. Specific structures of raw material 1, photosensitizers 2-4, and MS [MS+H] are described below. + The data is shown in Table 1.

[0033] Table 1. Structures of raw material 1, photosensitizer 2-4, and MS [MS+H] involved in Synthesis Examples 2-4 + data.

[0034]

[0035] Example 1 Preparation of a deep ultraviolet photoresist: 1. Raw material ratio: Main resin: 20 parts (phenolic resin, molecular weight approximately 1000-3000 g / mol); Photosensitizer: 3 parts (photosensitizer 1, synthesized from synthesis example 1); Photogenerated acid: 1.5 parts (diaryliodomonium salt); Crosslinking agent: 5 parts (hexamethoxymethyl melamine); Surfactant: 0.5 parts (sodium dodecyl sulfate); Organic solvent: 70 parts (propylene glycol methyl ether acetate).

[0036] 2. Preparation method: S1. Under light-protected conditions, dissolve 20 parts of phenolic resin in 70 parts of propylene glycol methyl ether acetate solvent and place the solution in a 500 mL three-necked flask. Purge the air three times with nitrogen to ensure a nitrogen atmosphere is formed. Maintain the stirring temperature at 50°C and the stirring speed at 300 rpm for 1.5 hours until the resin is completely dissolved and a homogeneous solution is formed. S2. Under nitrogen protection, add 3 parts photosensitizer 1, 1.5 parts diaryliodonium salt, and 5 parts hexamethoxymethylmelamine sequentially. Maintain the stirring temperature at 50°C and the stirring speed at 300 rpm, and continue the reaction for 0.75 hours; S3. Add 0.5 parts sodium dodecyl sulfate and stir for 10 minutes until homogeneous. Filter the resulting mixture through an 80-mesh sieve to remove particulate impurities, thus obtaining a deep ultraviolet photoresist. The product should be stored in a brown, light-proof bottle and refrigerated at 4°C for later use.

[0037] Examples 2-4 The preparation of a deep ultraviolet photoresist is carried out by referring to the preparation method of Example 1, except that the photosensitizer is replaced sequentially with photosensitizer 2-photosensitizer 4 synthesized in Synthesis Examples 2-4, and the rest is the same as in Example 1.

[0038] Comparative Example 1 The preparation of a deep ultraviolet photoresist is the same as in Example 1, except that no photosensitizer is added.

[0039] Comparative Example 2 The preparation of a deep ultraviolet photoresist is the same as in Example 1, except that the photoacid agent is not added.

[0040] Comparative Example 3 A deep ultraviolet photoresist was prepared by referring to the preparation method of Example 1, except that the mass fraction of the crosslinking agent was replaced with 18 parts, and the rest remained the same as in Example 1.

[0041] Performance testing: 1. Determination of the maximum UV absorption peak of the photosensitizer: The photosensitizer of the present invention was prepared into a 10... -5 The maximum ultraviolet absorption wavelength (λmax) of a mol / L propylene glycol methyl ether acetate (PMA) solution was measured, and the data are shown in Table 2. 2. A deep ultraviolet photoresist prepared in the examples and comparative examples was coated onto a silicon oxynitride substrate, and the spin-coating speed was adjusted to achieve a photoresist film thickness of 390 nm. The photoresist film was baked at 110 °C for 90 seconds. Subsequently, it was exposed on a 193 nm ISI microstepper (numerical aperture 0.6 and coherence 0.7) using a chromium-on-quartz binary mask. After exposure, the wafer was exposed at 130 °C and baked for 90 seconds. The photoresist was developed using a 2.38% by weight aqueous solution of tetramethylammonium hydroxide for 30 seconds. Sensitivity, resolution, and depth of focus data are shown in Table 2.

[0042] Table 2. Maximum UV absorption wavelength of the photosensitizer described in this invention, and sensitivity, resolution, and depth-of-focus data of a deep UV photoresist prepared in the examples and comparative examples.

[0043]

[0044] The data in Table 2 show an overall trend indicating that the deep ultraviolet photoresist examples of the present invention have significant performance advantages over the comparative examples: significantly reduced sensitivity, indicating higher exposure efficiency; continuously improved resolution, meaning finer imaging accuracy; and gradually increasing depth of focus, providing greater process tolerance. Specifically, with optimization of the photosensitizer type, sensitivity decreases, resolution improves, and depth of focus increases. Conversely, when the comparative examples lack key components (such as photosensitizers or photoacids) or use excessive crosslinking agents, performance deteriorates severely: sensitivity increases significantly, resolution decreases sharply, and depth of focus decreases significantly, highlighting the importance of balancing the component ratios of the present invention.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A deep ultraviolet photoresist, characterized in that, It comprises the following components by weight: main resin: 15-25 parts, photosensitizer: 1-5 parts, photoacidifier: 0.5-3 parts, crosslinking agent: 2-8 parts, surfactant: 0.1-1 parts, organic solvent: 60-80 parts; The photosensitizer has the structure shown in Formula 1: Formula 1; R1 is selected from: methyl, tert-butyl, cyano, nitro.

2. The deep ultraviolet photoresist according to claim 1, characterized in that, The main resin is phenolic resin.

3. The deep ultraviolet photoresist according to claim 1, characterized in that, The photosensitizer is any one of the compounds shown in the following structures: 。 4. The deep ultraviolet photoresist according to claim 1, characterized in that, The photogenerating acid is a diaryliodomonium salt.

5. The deep ultraviolet photoresist according to claim 1, characterized in that, The crosslinking agent is hexamethoxymethyl melamine.

6. The deep ultraviolet photoresist according to claim 1, characterized in that, The surfactant is sodium dodecyl sulfate.

7. The deep ultraviolet photoresist according to claim 1, characterized in that, The organic solvent is propylene glycol methyl ether acetate.

8. A method for preparing a deep ultraviolet photoresist according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Under light-protected conditions, dissolve the main resin in an organic solvent, stirring at 40-60°C for 1-2 hours; S2. Add photosensitizer, photoacid generator and crosslinking agent, and continue stirring for 0.5-1 hour; S3. Add surfactant, mix evenly, and filter to obtain the deep ultraviolet photoresist.

9. The method for preparing a deep ultraviolet photoresist according to claim 8, characterized in that, S1 is performed under a nitrogen atmosphere.

10. The application of a deep ultraviolet photoresist according to any one of claims 1-7 in semiconductor photolithography.

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