Polyimide negative photoresist composition

Abstract

This invention provides a polyimide negative photoresist composition comprising: 20 wt% to 80 wt% of a polyimide resin comprising a plurality of repeating units, wherein a portion of the repeating units are grafted with a functional group having an ethylene unsaturated bond, and the grafting rate of the polyimide resin is between 20% and 50%; 1 wt% to 20 wt% of a crosslinking agent; 0.15 wt% to 1 wt% of a photoacid generator; 0.1 wt% to 5 wt% of a photoinitiator; and the balance being a solvent. A polyimide negative photoresist composition is provided, which comprises: 20 wt% to 80 wt% of a polyimide resin comprising plural repeating units, wherein a part of the repeating units is grafted with a functional group with an ethylene unsaturated bond, and a grafting rate of the polyimide resin ranges from 20% to 50%; 1 wt% to 20 wt% of a cross-linking agent; 0.15 wt% to 1 wt% of a photo-acid generator; 0.1 wt% to 5 wt% of a photo-initiator; and a solvent.

Description

[Technical Field]

[0001] This invention relates to a polyimide negative photoresist composition, and more particularly to a polyimide negative photoresist composition that can be developed in aqueous phase. [Previous Technology]

[0002] Polyimide is a common insulating or protective layer material used in electronic products because of its good heat resistance and insulation properties.

[0003] In the packaging process of electronic products, photosensitive polyimide is first coated onto a substrate (e.g., a silicon wafer or a glass substrate). Then, through exposure and development, the polyimide precursor molecules cross-link and become patterned. Next, a high-temperature curing step is performed to cause the polyimide precursor to undergo a cyclization reaction, thereby forming a patterned insulating layer or protective layer.

[0004] Currently, commercially available polyimide negative photoresist compositions are mostly photosensitive resin compositions of solutions of polyamic ester (PAE), a polyimide precursor.

[0005] In view of this, there is an urgent need to develop a novel polyimide negative photoresist composition to solve the above problems. [Summary of the Invention]

[0006] The present invention provides a polyimide negative photoresist composition comprising: 20 wt% to 80 wt% of a polyimide resin comprising a plurality of repeating units, wherein a portion of the repeating units are grafted with a functional group having an ethylene unsaturated bond, and the grafting rate of the polyimide resin is between 20% and 50%; 1 wt% to 20 wt% of a crosslinking agent; 0.15 wt% to 1 wt% of a photoacid generator; 0.1 wt% to 5 wt% of a photoinitiator; and the balance being a solvent.

[0007] In this invention, by using cyclized polyimide resin (cyclization rate of 95%, 99%, or even 100%), the polyimide negative photoresist composition of this invention can be cured at low temperatures, reducing the warping problem of the formed photoresist film. Furthermore, due to the grafting of ethylene unsaturated functional groups onto the polyimide resin, these ethylene unsaturated functional groups can undergo photo- or thermal reactions, resulting in a cured photoresist film with excellent mechanical properties, facilitating subsequent advanced encapsulation and multilayer stacking. Moreover, the polyimide negative photoresist composition of this invention can be developed using an aqueous developer (e.g., TMAH developer) instead of commonly used polyimide negative photoresist developers (e.g., cyclopentanone solvent), which is more in line with the goal of sustainable development.

[0008] In this invention, the ungrafted repeating unit can be represented by the following formula (I-1):

[0009]

[0010] In this invention, the grafted repeating unit can be represented by the following formula (I-2):

[0011] Wherein R1 is a functional group with an ethylene unsaturated bond. In one embodiment, R1 may be, R2 may be hydrogen or a C1-4 alkyl group, and R3 may be a mono-bonded or C1-2 alkylene group.

[0012] In this invention, the alkyl or alkoxy group may be selectively substituted with or unsubstituted by a substituent. In this invention, the term "()alkylene" includes straight-chain and branched ()alkylene groups, for example, including straight-chain and branched C1-4 ()alkylene, C1-3 ()alkylene, or C1-2 ()alkylene groups; and specific examples include, but are not limited to: ()methylene, ()ethylene, ()propylene, ()isopropylene, ()butylene, ()isobutylene, ()sec-butylene, or ()tert-butylene.

[0013] In this invention, the grafted repeating unit can be represented by the following formula (I-3):

[0014] The ungrafted repeating unit of formula (I-1) can be reacted with glycidyl methacrylate (GMA) to obtain the grafted repeating unit of formula (I-3).

[0015] In this invention, the molecular weight of the polyimide resin may be between 15,000 and 30,000, for example, between 15,000 and 28,000, 15,000 and 25,000, 17,000 and 25,000 or 17,000 and 24,000.

[0016] In this invention, the grafting rate of polyimide resin can be between 20% and 50%, for example, between 20% and 45%, 20% and 40%, 25% and 40%, or 25% and 35%.

[0017] In this invention, the amount of polyimide resin added can be between 20wt% and 80wt%, for example, between 35wt% and 80wt%, 40wt% and 80wt%, 45wt% and 80wt%, 50wt% and 80wt%, 55wt% and 80wt%, 60wt% and 80wt%, 65wt% and 80wt%, or 65wt% and 75wt%.

[0018] In this invention, the amount of photoinitiator added can be between 0.1wt% and 5wt%, for example, between 0.1wt% and 4.5wt%, 0.1wt% and 4wt%, 0.5wt% and 4wt%, 0.5wt% and 3.5wt%, 0.5wt% and 3wt%, 0.5wt% and 2.5wt%, 1wt% and 2.5wt%, 1wt% and 2wt%, or 1wt% and 1.5wt%.

[0019] In this invention, there are no particular limitations on the type of photoinitiator. In one embodiment, the photoinitiator may be as shown in formula (II):

[0020]

[0021] In this invention, the amount of crosslinking agent added can be between 1 wt% and 20 wt%, for example, between 5 wt% and 20 wt%, 5 wt% and 18 wt%, 7 wt% and 18 wt%, 7 wt% and 15 wt%, 10 wt% and 15 wt%, or 10 wt% and 13 wt%.

[0022] In this invention, the crosslinking agent may include a photocrosslinking agent, a thermal crosslinking agent, or a combination thereof. There is no particular limitation on the type of crosslinking agent, as long as it involves an acid-initiated crosslinking reaction in the photoresist composition. In the composition of this invention, the amount of photocrosslinking agent monomer added is 1 wt% to 10 wt%, for example, it may be 1 wt% to 9 wt%, 1 wt% to 8 wt%, 1 wt% to 7 wt%, 1 wt% to 6 wt%, 1 wt% to 5 wt%, 1 wt% to 4 wt%, or 2 wt% to 4 wt%.

[0023] In the composition of the present invention, there are no particular limitations on the type of photocrosslinking agent monomer. In one embodiment, the photocrosslinking agent monomer may be as shown in formula (IV):

[0024]

[0025] The thermal crosslinking agent may be an alkoxyalkylamine resin, such as melamine resin, benzoguanamine resin, alkoxyalkylated melamine resin, or alkoxyalkylated urea resin. Specific examples of alkoxyalkylated amine resins include, but are not limited to, methylated polymers of 1,3,5-triazine-2,4,6-triamine with formaldehyde, methoxymethylated melamine resin, ethoxymethylated melamine resin, propoxymethylated melamine resin, methoxymethylated urea resin, ethylmethylated urea resin, or propoxymethylated urea resin. The above crosslinking agents may be used alone or in combination of two or more, without particular limitation.

[0026] In this invention, the amount of photoacid generator added can be between 0.15wt% and 1wt%, for example, between 0.15wt% and 0.9wt%, 0.15wt% and 0.8wt%, 0.15wt% and 0.7wt%, 0.15wt% and 0.6wt%, 0.15wt% and 0.55wt%, 0.2wt% and 0.55wt%, or 0.2wt% and 0.5wt%.

[0027] In this invention, there are no particular limitations on the type of photoacid generator, as long as it is a compound that can generate acid when exposed to active radiation. Among them, photoacid generators such as triazine and oxime sulfonate can be used. Specific examples of triazine photoacid generators include, but are not limited to, 2,4-bis(trichloromethyl)-6-[1,4-(methoxy)naphthyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methyl-2-furanyl)acetyl]-s-triazine, 2,4-bis(trichloromethyl)-6-[2-(3,5-diethoxyphenyl)acetyl]-s-triazine, or 2,4-bis(trichloromethyl)-6-(3-bromo-4-methoxy)phenacetylphenyl-s-triazine. Specific examples of oxime sulfonate photoacid generators include, but are not limited to, 2-methyl-α-[2-[[(propylsulfonyl)oxy]imino]-3(2H)-thienylidene, α-(2-propanesulfonyloxyimino-3-ene-o-methylacetonitrile), or α-(trifluoromethylsulfonyloxyimino)-phenylacetonitrile. The above photoacid generators can be used alone or in combination of two or more, without particular limitation. In one embodiment of the present invention, the photoacid generator can be represented by the following formula (III):

[0028]

[0029] In this invention, there are no particular limitations on the type of solvent, as long as the components in the negative photoresist composition are soluble therein. Specific examples of solvents include, but are not limited to, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, lactates (e.g., ethyl lactate, methyl lactate), propylene glycol monoalkyl ethers (e.g., propylene glycol monoethyl ether, propylene glycol monopropyl ether), ketones (e.g., cyclohexanone), or lactones (e.g., γ-butyrolactone). The above solvents can be used alone or in combination of two or more, without particular limitation.

[0030] The negative photoresist composition of the present invention may further include a surfactant, an inhibitor or other suitable additive.

[0031] The present invention further provides the use of the aforementioned polyimide photoresist composition in a low-temperature curing process, wherein low temperature refers to below 250°C. In one embodiment, the low-temperature curing temperature may be between 150°C and 250°C, for example, between 150°C and 200°C. In one embodiment, the low-temperature curing temperature may be approximately 170°C.

[0032] The present invention further provides a method for forming a patterned thin film using the aforementioned polyimide photoresist composition, comprising: coating the aforementioned polyimide negative photoresist composition onto a substrate to form a film layer; exposing and developing the film layer to pattern it; and heat-treating the patterned film layer to form a patterned polyimide thin film. The heat treatment temperature may be below 250°C, for example, between 150°C and 250°C or between 150°C and 200°C.

[0033] The present invention further provides an electronic device comprising: a polyimide film formed using the aforementioned polyimide negative photoresist composition.

Implementation Method

[0034] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed for different viewpoints and applications without departing from the spirit of the present invention.

[0035] Unless otherwise stated herein, the singular forms “a” and “the” used in the specification and the appended claims include one or a plurality of individuals.

[0036] Unless otherwise stated herein, the term "or" as used in the specification and the appended claims generally includes the meaning of "and / or".

[0037] Furthermore, in this document, the term "about" generally means within 20%, or 10%, or 5%, or 3%, or 2%, or 1%, or 0.5% of a given value or range. The given quantity is an approximate quantity, meaning that the meaning of "about" may be implied even without a specific description of "about". In addition, the terms "range from the first value to the second value" or "range between the first value and the second value" indicate that the range includes the first value, the second value, and other values ​​in between.

[0038] This disclosure will be illustrated in more detail by way of examples, but these examples are not intended to limit the scope of this disclosure. Unless otherwise specified, in the following preparation examples, embodiments and comparative examples, the temperature is Celsius, and the parts and percentages are by weight. The relationship between parts by weight and parts by volume is the same as the relationship between kilograms and liters.

[0039] Synthesis Example 1 - Preparation of Polyimide Resin

[0040] Under a dry nitrogen stream, 91.6 parts by weight of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (hereinafter referred to as APAF) and 62.0 parts by weight of 4,4'-oxobisphthalic anhydride (hereinafter referred to as ODPA) were dissolved in 367.6 parts by weight of diethylene glycol methyl ethyl ether (MEDG), and reacted at 60°C for 2 hours. 129.5 parts by weight of hexahydrophthalic anhydride (hereinafter referred to as HHPA) as a capping agent were added to the reaction mixture, and the mixture was stirred at 60°C for 4 hours. 0.34 g by weight of 1-ethylpyridine was added to the reaction mixture, and the mixture was stirred at 180°C for 4 hours. After stirring, the solution was added to 3 L of water, filtered to recover the precipitate, washed three times with water, and then dried using a vacuum dryer at 80°C for 20 hours. The infrared absorption spectrum of the obtained polymer solid was measured, and absorption peaks of the polyimide structure caused by polyimide were detected near 1780 cm⁻¹ and 1377 cm⁻¹. Its molecular weight is about 3000-20000 g / mol.

[0041] The above-mentioned polyimide resin (40.7 g) was mixed into PGMEA (86.7 g) and stirred at about 60°C until the resin was completely dissolved. The solution was then cooled to about 35°C. Next, the required amount of GMA (17.1 g) was added to the reaction flask, and the temperature was raised to 70°C. Finally, a solution of triphenylphosphine (0.47 g) in PGMEA (30 g) was added dropwise to the reaction solution through a dropping funnel. The reaction was continued at about 90°C for 10 hours to obtain a GMA-grafted polyimide resin solution. Its molecular weight is approximately 15,000-30,000 g / molar.

[0042] The preparation of the polyimide resins in Synthesis Examples 2 and 3 of the present invention was similar to that in Synthesis Example 1, except for some different parameters. The differences in process parameters and the characteristics of the polyimide resins from Synthesis Examples 1 to 2 are listed in Table 1 below.

[0043] Table 1

[0044] Preparation of polyimide negative photoresist composition

[0045] Polyimide negative photoresist compositions of Examples 1 to 4 and Comparative Examples 1 to 2 were prepared according to the composition formulations shown in Table 2 below, wherein the preparation methods are roughly as follows.

[0046] Polyimide resin, photoinitiator, photoacid generator, adhesion promoter, photocrosslinker, thermal crosslinker, inhibitor, and solvent were formulated according to the composition formulations shown in Table 2 below to prepare the polyimide photoresist compositions of Examples 1 to 3 and Comparative Examples 1 to 4. The polyimide resin used was the polyimide resin prepared in the aforementioned Synthetic Examples 1 to 3.

[0047] Table 2

[0048] Preparation of polyimide film

[0049] First, a 6-inch silicon wafer substrate was prepared. Next, according to Table 3 below, the polyimide negative photoresist compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were uniformly coated onto the substrate by spin coating. Then, the substrate was soft-baked at 120°C for 3 minutes, and then exposed to the polyimide negative photoresist composition coated on the substrate surface using an exposure machine. Afterward, 2.38 wt% TMAH developer was sprayed at 23°C for 120 seconds for development. Then, the substrate was hard-baked at 150°C for 30 minutes and then at 170°C for 2 hours to form a polyimide film from the polyimide negative photoresist composition.

[0050] Then, the mechanical properties of the obtained polyimide film were tested, and the results are listed in Table 3 below.

[0051] Table 3

[0052] As shown in Table 3, compared to Comparative Example 1, when the content of the photoacid generator in the polyimide negative photoresist composition exceeds 0.1 wt% (Examples 1 to 3), the resulting polyimide film exhibits better mechanical properties. Furthermore, as shown in Comparative Example 2, when the grafting rate of the polyimide resin is too high, the resulting film has poor mechanical properties and low resolution; conversely, in Examples 1 to 3, when the polyimide resin has an appropriate grafting rate, polyimide films with good mechanical properties and resolution can be obtained. The above results show that when the grafting rate of the polyimide resin is within a specific range and the content of the photoacid generator exceeds 0.1 wt%, the film obtained from the polyimide negative photoresist composition at low temperature (170°C) exhibits excellent mechanical properties.

[0053] The above embodiments are merely examples for the purpose of illustration. The scope of the rights claimed by this invention shall be determined by the scope of the patent application, and not limited to the above embodiments.

Claims

1. A polyimide negative photoresist composition, comprising: The polyimide resin comprises 20 wt% to 80 wt% of a plurality of repeating units, wherein a portion of the repeating units are grafted with a functional group having an ethylene unsaturated bond, and the grafting rate of the polyimide resin is between 25% and 40%; 1 wt% to 20 wt% of a crosslinking agent; 0.15 wt% to 1 wt% of a photoacid generator; 0.1 wt% to 5 wt% of a photoinitiator; and the balance being a solvent; wherein the grafted repeating units are as shown in formula (I-2): Wherein, R1 is hydrogen, R2 is hydrogen or C1-4 alkyl, and R3 is a single bond or C1-2 alkylene.

2. The polyimide negative photoresist composition as claimed in claim 1, wherein the grafted repeating unit is shown in formula (I-3):

3. The polyimide negative photoresist composition as claimed in claim 1, wherein the molecular weight of the polyimide resin is between 15,000 and 30,000.

4. The polyimide negative photoresist composition as claimed in claim 1, wherein the photoinitiator is of the following formula (II):

5. The polyimide negative photoresist composition as claimed in claim 1, wherein the photoacid generator is of the following formula (III):

6. The polyimide negative photoresist composition as claimed in claim 1, wherein the crosslinking agent is a melamine resin.

7. The polyimide negative photoresist composition as claimed in claim 1, wherein the crosslinking agent is shown in formula (IV):