Preparation method and application of yellowing-resistant negative thick film photoresist composition

Abstract

The invention relates to the technical field of photoresist, in particular to a preparation method and application of an anti-yellowing negative thick film photoresist composition which comprises the following components in percentage by weight: 45-70% of SU8 resin, 7-30% of alicyclic epoxy resin, 5-10% of a cross-linking agent, 2-10% of a photoacid generator, 10-20% of a solvent and a flatting agent, the concentration of the flatting agent in the photoresist composition is 100-200ppm, and the yellowing resistance of the material can be improved by increasing the structural proportion of the alicyclic compound in molecules.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoresist technology, in particular to the preparation method and application of a yellowing-resistant negative thick film photoresist composition. BACKGROUND

[0002] SU-8 resin is a functional epoxy polymer with multiple functional groups. Due to its unique molecular design, it contains 8 epoxy groups in its structure, making it have high functionality, high branching degree, high reactivity and other characteristics. At the same time, the molecular weight of SU-8 resin is relatively low, which is beneficial to the formation of a high-solid and low-defect formulation system. Therefore, SU-8 resin is widely used in thick film photoresist with high aspect ratio. However, it is found in actual application that the resin has a tendency to become brittle after curing, which is prone to cracking due to shrinkage, affecting the performance of the material.

[0003] US6716568, US6210862, US5102772 disclose that the addition of polyol active diluent, polymeric dilution resin, and small molecule active diluent can effectively improve the cracking of the coating film. However, it is found through accelerated aging test that the rigid aromatic groups contained in the material are prone to yellowing under long-term ultraviolet radiation, which affects the application of the material in optical devices. SUMMARY

[0004] In view of the above situation, in order to overcome the defects of the prior art, the present application provides a preparation method and application of a yellowing-resistant negative thick film photoresist composition by introducing a series of alicyclic epoxy polymers and alicyclic crosslinking agents.

[0005] The technical scheme adopted by the present application is as follows: a yellowing-resistant negative thick film photoresist composition, including the following percentage by weight of components: SU8 resin 45%-70%, alicyclic epoxy resin 7%-30%, crosslinking agent 5-10%, photoacid generator 2-10%, solvent 10-20%; the yellowing-resistant negative thick film photoresist composition further includes a leveling agent, and the concentration of the leveling agent in the photoresist composition is 100-200 ppm.

[0006] Further, the alicyclic epoxy resin is one or more of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexyl carboxylate, ethylene dioxy cyclohexene, bis(7-oxabicyclo[4.1.0]3-heptamethyl) adipate, dioxodicyclopentadiene, poly[(2-oxiranyl)-1,2-cyclohexanediol] 2-ethyl-2-(hydroxymethyl)-1,3-propanediol ether, hydrogenated bisphenol A diglycidyl ether, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, 1,4-bis[(glycidyl oxygen) methyl] cyclohexane, and hydrogenated bisphenol A phenolic epoxy resin.

[0007] Further, the crosslinking agent is one or more of 1,2-bis-(2-hydroxyethoxy)-cyclohexane, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, 4-(hydroxymethyl)cyclohexanol, 2,2-(cyclohexane-1,1-diyl)bis(ethane-1-ol), bicyclo[2.2.2]octane-1,4-diol.

[0008] Further, the photoacid generator is a cationic acid generator of the sulfonium or iodonium salt type.

[0009] Further, the solvent is one or more of gamma-butyrolactone, cyclopentanone, propylene glycol methyl ether acetate, cyclohexanone, methyl ethyl ketone, butanone.

[0010] Further, the leveling agent (i.e., surfactant) is preferably one or more of 3M FC-4432, DIC MEGAFACE F563, F556.

[0011] The application also discloses a preparation method of the yellowing-resistant negative thick-film photoresist composition.

[0012] Step one, the film-forming resin, crosslinking agent, photoacid generator, solvent, leveling agent are mixed in proportion and sealed and stirred; step two, after the stirring in step one is completed, a filter membrane is used to obtain the photoresist composition after circulation filtration.

[0013] The application also discloses application of the yellowing-resistant negative thick-film photoresist composition in the yellow light process section in the fields of PCB, semiconductor, panel display and packaging.

[0014] The application has the following beneficial effects by adopting the above structure: the proportion of the alicyclic compound in the molecule is increased, and the yellowing resistance of the material is improved;

[0015] Stable structure: the alicyclic compound has a stable alicyclic structure, which can reduce the active chemical bonds in the molecule, thereby reducing the possibility of chemical reaction of the material in the photo-oxidation process, and further improving the yellowing resistance of the material;

[0016] Good weather resistance: the ordinary bisphenol A type epoxy resin has a benzene ring, and the poor weather resistance is a common defect of the bisphenol A type epoxy resin. The alicyclic epoxy resin has a stable alicyclic structure instead of the benzene ring, and the alicyclic epoxy resin has good weather resistance and yellowing resistance;

[0017] Containing aromatic ring: some aromatic compounds may undergo yellowing reaction under light, and the alicyclic compound generally does not contain an aromatic ring, thereby reducing the possibility of yellowing;

[0018] Inhibiting radical reaction: During the photo-oxidation process of the material, the generation and reaction of free radicals is one of the important reasons for yellowing. The structure of the alicyclic compound can inhibit the formation or reaction of free radicals, thereby reducing the occurrence of yellowing. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0020] The comparative example is obtained by mixing 75% SU8 type epoxy resin, 5% photoacid generator, 200 ppm leveling agent, and the remaining component being solvent 20% according to the above proportions, sealing and stirring, using a filter membrane after complete dissolution, and cyclically filtering, and then storing in the dark for testing.

[0021] In example 1, 60% SU8 type epoxy resin, 15% aliphatic epoxy, 7% crosslinking agent I, 5% photoacid generator, 200 ppm leveling agent SF1, and the remaining component being solvent 13% are mixed according to the above proportions, sealed and stirred, and then stored in the dark for testing after complete dissolution and cyclically filtering using a filter membrane.

[0022] In examples 2-14, the SU8 type epoxy resin and the aliphatic epoxy are mixed according to the corresponding proportions in table 1 for different examples 2-14, and the crosslinking agent, the photoacid generator, the leveling agent, and the solvent are mixed according to the corresponding proportions in table 1 for the examples, sealed and stirred, and then stored in the dark for testing after complete dissolution and cyclically filtering using a filter membrane, according to the operation steps of example 1.

[0023] In examples 15-20, the SU8 type epoxy resin and the aliphatic epoxy are mixed (a plurality of types are mixed according to the corresponding types and proportions before and after “ / ”) according to the corresponding proportions in table 1 for different examples 2-14, and the crosslinking agent (a plurality of types are mixed according to the corresponding types and proportions before and after “ / ”), the photoacid generator, the leveling agent, and the solvent are mixed according to the corresponding proportions in table 1 for the examples, sealed and stirred, and then stored in the dark for testing after complete dissolution and cyclically filtering using a filter membrane, according to the operation steps of example 1.

[0024] Graphics and resolution testing methods: The samples from the above examples were spin-coated onto a silicon wafer, with the coating thickness controlled to 10 μm ± 1 μm by adjusting the spin speed. After spin coating, the samples were baked on a hot plate at 65°C for 1 minute and 95°C for 5-10 minutes. After baking, the samples were exposed using an I-line exposure machine with an exposure dose of 200-250 mj / cm². After exposure, the samples were baked again at 65°C for 1 minute and 95°C for 5-10 minutes. PGMEA was used for development for 2-3 minutes, and IPA was used for rinsing for 1 minute. The photoresist was observed for cracks under a microscope (no cracks were detected: Δ indicates excellent, minor cracks were detected: □ indicates fair, and severe cracks were detected: ¤ indicates poor). The photoresist resolution was measured using a scanning electron microscope (SEM).

[0025] Temperature resistance test method: collect the above-mentioned fully cured resin and perform a thermal weight loss test, and record the temperature (T 5％ ), T 5％ >300℃, use Δ to indicate excellent T 5％ At 280-300℃, □ is used to indicate general T 5％ If the temperature is less than 280℃, ¤ is used to indicate poor quality.

[0026] Adhesion test: According to ASTM D3359-2002 "Adhesion by Tape Method" test criteria, the above-mentioned example samples were spin-coated on a silicon wafer. The coating thickness was controlled to 10 μm + / - 1 μm by adjusting the rotation speed. After spin coating, the samples were baked on a hot plate at 65°C for 1 minute and 95°C for 5-10 minutes. The pattern was scratched with a grid knife and the adhesion of the pattern to the substrate was tested with a special tape. 5B is indicated by Δ, 3B-4B is indicated by □, and <3B is indicated by □. Indicates poor.

[0027] Yellowing resistance test: Using the ASTM G154-2006 test method, accelerated aging experiments were conducted using a 340nm lamp and full illumination of 0.89W / (m2·nm). According to CIE15:2004 specifications, a colorimeter was used to measure the yellowness index (YI). The color difference before and after irradiation was calculated. A color difference value <0.5 was expressed as Δ for excellent, a color difference value of 0.5-1.0 was expressed as □ for fair, and a color difference value >1.0 was expressed as Indicates poor.

[0028] Table 1 Comparison of adhesion, temperature resistance, cracking and yellowing resistance of the examples

[0029]

[0030] In Table 1, PI is 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate;

[0031] P2 is dioxetane cyclohexene;

[0032] P3 is bis(7-oxabicyclo[4.1.0]3-heptamethyl)hexanedioate;

[0033] P4 is dioxetane dicyclopentadiene;

[0034] P5 is poly[(2-oxiranylmethyl)-1,2-cyclohexanediol] 2-ethyl-2-(hydroxymethyl)-1,3- propanediol ether;

[0035] P6 is hydrogenated bisphenol A diglycidyl ether;

[0036] P7 is 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester;

[0037] P8 is 1,4-bis[(glycidyloxy)methyl]cyclohexane;

[0038] P9 is hydrogenated bisphenol A novolac epoxy resin.

[0039] In Table 1, I is 1,2-bis-(2-hydroxyethoxy)-cyclohexane;

[0040] II is 1,4-cyclohexanedimethanol;

[0041] III is 2,2'-(cyclohexane-1,1-diyl)bis(ethane-1-ol);

[0042] IV is 1,4-cyclohexanediol;

[0043] V is 4-(hydroxymethyl)cyclohexanol;

[0044] VI is bicyclo[2.2.2]octane-1,4-diol.

[0045] In Table 1, SF1 is 3M FC-4432; SF2 is DIC MEGAFACE F563; and SF3 is F556.

[0046] It has to be noted that, as used herein, the terms "includes" and / or "contains", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0047] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A yellowing-resistant negative thick-film photoresist composition, characterized in that: The invention comprises the following components in percentage by weight: 45%-70% of SU8 resin, 7%-30% of alicyclic epoxy resin, 5%-10% of crosslinking agent, 2%-10% of photoacid generator, and 10%-20% of solvent; The photoresist composition further comprises a leveling agent, and the concentration of the leveling agent in the photoresist composition is 100-200 ppm.

2. The yellowing-resistant negative thick-film photoresist composition according to claim 1, wherein The alicyclic epoxy resin is one or more of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, vinylcyclohexene dioxide, bis(7-oxabicyclo[4.1.0]3-heptylmethyl)adipate, dipolycyclopentadiene dioxide, poly[(2-oxiranyl)-1,2-cyclohexanediol]2-ethyl-2-(hydroxymethyl)-1,3-propylene glycol ether, hydrogenated bisphenol A diglycidyl ether, 4,5-epoxycyclohexane-1,2-dicarboxylic acid diglycidyl ester, 1,4-bis[(glycidyloxy)methyl]cyclohexane, and hydrogenated bisphenol A novolac epoxy resin.

3. The yellowing-resistant negative thick-film photoresist composition according to claim 1, characterized in that: The crosslinking agent is one or more of 1,2-bis-(2-hydroxyethoxy)-cyclohexane, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, 4-(hydroxymethyl)cyclohexanol, 2,2-(cyclohexane-1,1-diyl)bis(ethane-1-ol), and bicyclo[2.2.2]octane-1,4-diol.

4. The yellowing-resistant negative thick-film photoresist composition according to claim 1, characterized in that: The photoacid generator is a cationic acid generator of the sulfonium salt or iodonium salt type.

5. The yellowing-resistant negative thick-film photoresist composition according to claim 1, wherein The solvent is one or more of gamma-butyrolactone, cyclopentanone, propylene glycol methyl ether acetate, cyclohexanone, methyl ethyl ketone, and butanone.

6. The yellowing-resistant negative thick-film photoresist composition according to claim 1, wherein The leveling agent is one or more of 3MFC-4432, DIC MEGAFACE F563, and F556.

7. The method for preparing the yellowing-resistant negative thick-film photoresist composition according to claims 1 to 6, characterized in that: The steps include: Step 1: Mix the film-forming resin, cross-linking agent, photoacid generator, solvent, and leveling agent in proportion, and stir in a sealed container; Step 2: After stirring in step 1 until completely dissolved, filter the mixture using a filter membrane and perform cyclic filtration to obtain a photoresist composition.

8. Application of the yellowing-resistant negative thick-film photoresist composition according to claims 1 to 6 in yellow light process segments in the fields of PCB, semiconductor, panel display, packaging, etc.

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