Anti-reflection coating and preparation method thereof

Abstract

The invention relates to the technical field of photoetching, and provides an anti-reflection coating and a preparation method thereof. The anti-reflection coating comprises the following components in parts by weight: 25 parts of matting resin, 4-9 parts of phenol type novolac epoxy resin, 2-5 parts of a catalyst, 6-10 parts of a cross-linking agent, 2-6 parts of a benzoic anhydride-containing compound, 1-2 parts of a photo-acid generator and 600-1200 parts of a solvent, the phenol type novolac epoxy resin comprises phenol type novolac epoxy resin NPPN-631 and phenol type novolac epoxy resin F-44 in a weight ratio of (1-5): 1. According to the technical scheme, the problem that the solvent resistance of a coating formed by an anti-reflection coating in the prior art is poor is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photolithography, and in particular to an anti-reflective coating and a preparation method thereof. Background Art

[0002] Anti-reflective coatings (ARCs) play a crucial role in photolithography, with their performance directly impacting the precision and effectiveness of the lithography process. As chip manufacturing continues to evolve toward smaller sizes and higher integration densities, the sensitivity of the lithography process to environmental factors continues to increase. As a key functional layer between the photoresist and the substrate, ARCs have become a key research area.

[0003] Traditional anti-reflective coatings have numerous limitations in practical applications, with poor solvent resistance being a prominent issue. In the photolithography process, various organic solvents are used in steps such as photoresist development and etching. If these solvents penetrate the anti-reflective coating, they can reduce adhesion between the coating and the substrate, leading to coating peeling and pattern deformation, seriously compromising the precision and quality of the lithographic pattern.

[0004] Patent CN112680052A, a patent for an antireflective coating composition for photolithography, utilizes a specially formulated matting resin to enhance the coating's light absorption, etching selectivity, and storage stability. However, since the molecular weight of the matting resin is a key factor in solvent resistance and etching rate, a higher molecular weight improves solvent resistance but reduces etching rate, while a lower molecular weight fails to guarantee solvent stability. This suggests that relying solely on matting resin to optimize solvent resistance inevitably compromises other coating properties.

[0005] Existing technologies for improving the solvent resistance of anti-reflective coatings have primarily focused on adjusting the resin type or adding functional additives. While using a single novolac epoxy resin as the base resin can improve the coating's film-forming properties, it still struggles to resist solvent erosion in complex photolithography environments, resulting in poor solvent resistance for the resulting anti-reflective coating. The combined use of multiple novolac epoxy resins is primarily aimed at improving the coating's high-temperature resistance, but research on enhancing solvent resistance is limited.

[0006] Therefore, developing an anti-reflective coating with excellent solvent resistance in a photolithography environment is of great significance for meeting the development needs of high-end fields such as chip manufacturing. Summary of the Invention

[0007] The present invention provides an anti-reflective coating and a preparation method thereof, which solves the problem in the related art that the anti-reflective coating has poor solvent resistance.

[0008] The technical solutions of the present invention are as follows: The present invention provides an anti-reflective coating comprising the following components in parts by weight: 25 parts of matting resin, 4-9 parts of phenol-type novolac epoxy resin, 2-5 parts of catalyst, 6-10 parts of cross-linking agent, 2-6 parts of phthalic anhydride compound, and 600-1200 parts of solvent; The phenol-type novolac epoxy resin includes phenol-type novolac epoxy resin NPPN-631 and phenol-type novolac epoxy resin F-44 in a weight ratio of 1 to 5:1.

[0009] The anti-reflective coating of the present invention is mainly composed of a matting resin and a phenol-type novolac epoxy resin. Under the action of a catalyst, a cross-linking agent, a benzoic anhydride compound, a photoacid generator and a solvent, an anti-reflective coating with good stability can be formed. After curing to form an anti-reflective coating, the anti-reflective coating can effectively prevent the penetration of solvent molecules, thereby improving the solvent resistance of the coating.

[0010] In the anti-reflective coating of the present invention, the weight ratio of the phenol-type novolac epoxy resin with model NPPN-631 to the phenol-type novolac epoxy resin with model F-44 is 1 to 5:1, for example, it can be 1:1, 1.5:1, 2:1, 3:1, 4:1, 5:1, preferably 1:1, 3:1, 4:1, 5:1, and more preferably 3:1, 4:1.

[0011] In the anti-reflective coating of the present invention, when the weight ratio of the phenol-type novolac epoxy resin (NPPN-631) to the phenol-type novolac epoxy resin (F-44) is 3-4:1, the solvent resistance of the anti-reflective coating can be further improved. After the anti-reflective coating is treated with ethyl lactate, the peeling percentage of the anti-reflective coating is reduced to 0.56%-0.58%. When the weight ratio of the phenol-type novolac epoxy resin (NPPN-631) to the phenol-type novolac epoxy resin (F-44) is outside the range of 3-4:1, the solvent resistance of the anti-reflective coating is relatively poor.

[0012] In the anti-reflective coating of the present invention, the addition of a catalyst can accelerate the chemical reactions between the various components in the coating, particularly promoting the interaction between the base resin and the crosslinking agent. Under the action of the catalyst, the anti-reflective coating can reach a certain degree of cure in a relatively short period of time, forming an anti-reflective coating, thereby improving production efficiency. Furthermore, the catalyst can also lower the temperature required for the various components in the anti-reflective coating to react, reducing energy consumption and ultimately forming a more uniform and dense crosslinked network structure, thereby improving the performance of the anti-reflective coating. The catalyst can be one or both of p-toluenesulfonate and phthalate, preferably p-toluenesulfonate, and can be sodium p-toluenesulfonate or magnesium p-toluenesulfonate, more preferably sodium p-toluenesulfonate.

[0013] In the anti-reflective coating of the present invention, the crosslinking agent can react with other components in the anti-reflective coating so that the prepared anti-reflective coating can form a three-dimensional network crosslinked structure at high temperature, thereby significantly improving the stability and adhesion of the coating formed by the anti-reflective coating. The crosslinking agent can be any one or more crosslinking agents in the art, for example, urea-formaldehyde resin, melamine-formaldehyde resin, preferably a combination of urea-formaldehyde resin and melamine-formaldehyde resin. The urea-formaldehyde resin can be of the type CYMEL U-662, CYMEL U-663, CYMEL U-1051, or CYMEL UI-19-1, with CYMEL U-662 being the preferred type; the melamine-formaldehyde resin can be of the type CYMEL 303LF or CYMEL 304, with CYMEL 303LF being the preferred type.

[0014] In the anti-reflective coating of the present invention, when the crosslinking agent includes urea-formaldehyde resin and melamine-formaldehyde resin, the weight ratio of urea-formaldehyde resin to melamine-formaldehyde resin is 2-4:1, for example, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, preferably 4:1.

[0015] As a further technical solution, the raw materials of the matting resin include acrylic acid, methyl methacrylate and dichloroquinoline.

[0016] In the anti-reflective coating of the present invention, the matting resin is prepared from acrylic acid, methyl methacrylate and quinclorac in a molar ratio of 1:1:1 according to a conventional method, and the weight-average molecular weight of the matting resin is 15,000.

[0017] As a further technical solution, the phthalic anhydride-containing compound includes one or more of trimellitic anhydride, pyromellitic dianhydride, and 3-hydroxyphthalic anhydride.

[0018] As a further technical solution, when the phthalic anhydride-containing compound includes trimellitic anhydride and 3-hydroxyphthalic anhydride, the weight ratio of trimellitic anhydride to 3-hydroxyphthalic anhydride is 4 to 5:1, for example, it can be 4:1, 4.2:1, 4.5:1, 5:1, preferably 4:1, 5:1.

[0019] In the anti-reflective coating of the present invention, the addition of a phthalic anhydride-containing compound can work together with a crosslinking agent to improve the crosslinking degree of the anti-reflective coating. The phthalic anhydride-containing compound includes one or more of trimellitic anhydride, pyromellitic dianhydride, and 3-hydroxyphthalic anhydride. When the phthalic anhydride-containing compound includes trimellitic anhydride and 3-hydroxyphthalic anhydride, the anti-reflective performance of the coating can be improved while not affecting the solvent resistance of the anti-reflective coating. It is speculated that the reason may be that the combined use of trimellitic anhydride and 3-hydroxyphthalic anhydride improves the crosslinking network of the anti-reflective coating and enables the anti-reflective coating to spread better on the substrate surface, forming a more uniform coating, thereby reducing the reflection of light in the anti-reflective coating and improving the anti-reflective performance of the anti-reflective coating.

[0020] In the present invention, when the weight ratio of trimellitic anhydride to 3-hydroxyphthalic anhydride is 4-5:1, the antireflection ability of the antireflective coating formed by the antireflective coating can be further improved, so that the refractive index of the antireflective coating is reduced to 1.39-1.42. When the weight ratio of trimellitic anhydride to 3-hydroxyphthalic anhydride is outside the range of 4-5:1, the antireflection ability of the antireflective coating is poor.

[0021] As a further technical solution, the solvent includes one or both of propylene glycol methyl ether acetate and cyclohexanone, preferably cyclohexanone.

[0022] The present invention provides a method for preparing an anti-reflective coating, which is used to prepare the anti-reflective coating, comprising the following steps: adding the matting resin, phenol-type novolac epoxy resin, a catalyst, a crosslinking agent, and a benzoic anhydride-containing compound to the solvent, mixing them evenly, to obtain the anti-reflective coating.

[0023] As a further technical solution, when the mixing is uniform, the temperature is 90-100° C., the stirring speed is 100-200 rpm, and the stirring time is 3-5 hours.

[0024] The working principle and beneficial effects of the present invention are: The anti-reflective coating of the present invention incorporates two phenolic novolac epoxy resins, NPPN-631 and F-44. By combining these two different phenolic novolac epoxy resins, the solvent resistance of the resulting anti-reflective coating is improved. In the prior art, phenolic novolac epoxy resins are often used to improve film-forming properties and high-temperature resistance. However, the present invention utilizes the complexity of the internal structure of the phenolic novolac epoxy resin to enhance the solvent resistance of the anti-reflective coating. The differences in active epoxy groups between the NPPN-631 and F-44 phenolic novolac epoxy resins allow the crosslinked network to maintain density while also providing a certain degree of molecular chain adjustability. This prevents brittle cracking of the anti-reflective coating resulting from excessive crosslinking density, thereby enhancing the overall structural stability of the cured anti-reflective coating and significantly improving its solvent resistance. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0026] In the following examples and comparative examples, the matting resin was prepared from acrylic acid, methyl methacrylate, and quinclorac in a molar ratio of 1:1:1 according to a conventional method, and its weight-average molecular weight was 15,000; The model of urea-formaldehyde resin is CYMEL U-662, and the model of melamine-formaldehyde resin is CYMEL 303LF.

[0027] Example 1 An anti-reflective coating comprises the following steps: adding 25 parts of matting resin, 2 parts of phenol-type novolac epoxy resin (model NPPN-631), 2 parts of phenol-type novolac epoxy resin (model F-44), 2 parts of sodium p-toluenesulfonate, 4.8 parts of urea-formaldehyde resin, 1.2 parts of melamine-formaldehyde resin, 1 part of trimellitic anhydride, and 1 part of 3-hydroxyphthalic anhydride to 600 parts of cyclohexanone; stirring at 90° C. and 100 rpm for 5 hours; and mixing uniformly to obtain the anti-reflective coating.

[0028] Example 2 An anti-reflective coating comprises the following steps: adding 25 parts of matting resin, 4.5 parts of phenol-type novolac epoxy resin (model NPPN-631), 4.5 parts of phenol-type novolac epoxy resin (model F-44), 5 parts of sodium p-toluenesulfonate, 8 parts of urea-formaldehyde resin, 2 parts of melamine-formaldehyde resin, 3 parts of trimellitic anhydride, and 3 parts of 3-hydroxyphthalic anhydride to 1200 parts of cyclohexanone; stirring at 100° C. and 200 rpm for 3 hours; and mixing uniformly to obtain the anti-reflective coating.

[0029] Example 3 The only difference between this embodiment and embodiment 2 is that in this embodiment, 7.5 parts of phenol-type novolac epoxy resin (model NPPN-631) and 1.5 parts of phenol-type novolac epoxy resin (model F-44) are added.

[0030] Example 4 The only difference between this embodiment and embodiment 2 is that in this embodiment, 6.75 parts of phenol-type novolac epoxy resin (model NPPN-631) and 2.25 parts of phenol-type novolac epoxy resin (model F-44) are added.

[0031] Example 5 The only difference between this embodiment and embodiment 2 is that in this embodiment, 7.2 parts of phenol-type novolac epoxy resin (model NPPN-631) and 1.8 parts of phenol-type novolac epoxy resin (model F-44) are added.

[0032] Example 6 The only difference between this embodiment and embodiment 5 is that in this embodiment, 5.4 parts of trimellitic anhydride and 0.6 parts of 3-hydroxyphthalic anhydride are added.

[0033] Example 7 The only difference between this embodiment and embodiment 5 is that, in this embodiment, 4.8 parts of trimellitic anhydride and 1.2 parts of 3-hydroxyphthalic anhydride are added.

[0034] Example 8 The only difference between this embodiment and embodiment 5 is that, in this embodiment, 5 parts of trimellitic anhydride and 1 part of 3-hydroxyphthalic anhydride are added.

[0035] Comparative Example 1 The only difference between this comparative example and Example 2 is that in this comparative example, the phenol-type novolac epoxy resin with the model number F-44 is replaced by an equal amount of the phenol-type novolac epoxy resin with the model number NPPN-631.

[0036] Comparative Example 2 The only difference between this comparative example and Example 2 is that in this comparative example, the phenol-type novolac epoxy resin with the model number NPPN-631 is replaced by an equal amount of the phenol-type novolac epoxy resin with the model number F-44.

[0037] Comparative Example 3 The only difference between this comparative example and Example 2 is that in this comparative example, no phenol-type novolac epoxy resin is added.

[0038] Experimental Example 1 The anti-reflective coatings prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were spin-coated onto silicon wafers and baked for cross-linking at 200°C for 120 seconds to obtain silicon wafers coated with the anti-reflective coatings. The solvent resistance test was performed. During the test, the thickness of the anti-reflective coating after curing was measured at five random locations using an ellipsometer, and the average value was taken to obtain the film thickness before the solvent resistance test. The cured film was spin-coated with ethyl lactate for 30 seconds, spin-dried for 30 seconds, and after removing the solvent, the thickness of the anti-reflective coating was measured at five random locations using an ellipsometer to obtain the film thickness after the solvent resistance test. A peeling percentage test was performed according to the following formula: peeling percentage = (film thickness before solvent resistance test - film thickness after solvent resistance test) / film thickness before solvent resistance test × 100%. The test results are shown in Table 1.

[0039] Table 1 Solvent resistance test results of Examples 1 to 5 and Comparative Examples 1 to 3

[0040] Compared with Comparative Examples 1-3, the anti-reflective coatings prepared in Examples 1-5 had a reduced peeling percentage, indicating that the addition of two phenol-type novolac epoxy resins, NPPN-631 and F-44, to the anti-reflective coating can improve the solvent resistance of the anti-reflective coating by using two different types of phenol-type novolac epoxy resins. This allows the anti-reflective coating to be prepared. After ethyl lactate treatment, the peeling percentage of the anti-reflective coating is reduced to below 0.75%.

[0041] Experimental Example 2 The anti-reflective coatings prepared in Examples 5 to 8 were spin-coated onto silicon wafers and cross-linked by baking at 200°C for 120 seconds to obtain silicon wafers coated with the anti-reflective coatings. The refractive index n of the anti-reflective coatings was measured using an ellipsometer. The test results are shown in Table 2. Table 2 Refractive index test results of Examples 5 to 8

[0042] Compared with Examples 5 and 6, the refractive index of the anti-reflective coatings prepared in Examples 7 and 8 is lower, indicating that when the weight ratio of trimellitic anhydride to 3-hydroxyphthalic anhydride in the anti-reflective coating is 4 to 5:1, the anti-reflective ability of the anti-reflective coating formed by the anti-reflective coating can be improved.

[0043] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An anti-reflective coating, characterized in that: The composition comprises the following components in parts by weight: 25 parts of matting resin, 4-9 parts of phenol-type novolac epoxy resin, 2-5 parts of catalyst, 6-10 parts of cross-linking agent, 2-6 parts of phthalic anhydride compound, and 600-1200 parts of solvent; The phenol-type novolac epoxy resin includes phenol-type novolac epoxy resin NPPN-631 and phenol-type novolac epoxy resin F-44 in a weight ratio of 1 to 5:

1.

2. The anti-reflective coating according to claim 1, characterized in that: The raw materials of the matting resin include acrylic acid, methyl methacrylate and quinclorac.

3. The anti-reflective coating according to claim 1, characterized in that: The phthalic anhydride-containing compound includes one or more of trimellitic anhydride, pyromellitic dianhydride, and 3-hydroxyphthalic anhydride.

4. The anti-reflective coating according to claim 3, characterized in that: When the phthalic anhydride-containing compound includes trimellitic anhydride and 3-hydroxyphthalic anhydride, the weight ratio of trimellitic anhydride to 3-hydroxyphthalic anhydride is 4-5:

1.

5. The anti-reflective coating according to claim 1, characterized in that: The catalyst comprises one or both of p-toluenesulfonate and phthalate.

6. The anti-reflective coating according to claim 1, characterized in that: The cross-linking agent includes one or both of urea-formaldehyde resin and melamine-formaldehyde resin.

7. The anti-reflective coating according to claim 1, characterized in that: When the cross-linking agent comprises urea-formaldehyde resin and melamine-formaldehyde resin, the weight ratio of the urea-formaldehyde resin to the melamine-formaldehyde resin is 4:

1.

8. The anti-reflective coating according to claim 1, characterized in that: The solvent includes one or both of propylene glycol methyl ether acetate and cyclohexanone.

9. A method for preparing an anti-reflective coating, for preparing an anti-reflective coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: The matting resin, phenol-type novolac epoxy resin, catalyst, crosslinking agent and benzoic anhydride-containing compound are added into the solvent and mixed evenly to obtain the anti-reflective coating.

10. The method for preparing an anti-reflective coating according to claim 9, characterized in that: When the mixing is uniform, the temperature is 90-100° C., the stirring speed is 100-200 rpm, and the stirring time is 3-5 hours.

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