A positive photoresist composition having excellent stability

Abstract

The application provides a positive photoresist composition, which comprises a phenolic resin, a photosensitive compound and a mixed solvent, wherein the mixed solvent comprises a first solvent and a second solvent, the first solvent is selected from at least one of ethyl lactate, ethyl 3-ethoxypropionate, 4-methyl-2-pentanone and 2-heptanone; and the second solvent is selected from at least one of ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether acetate, ethyl acetate and n-butyl acetate. The photoresist composition provided by the application has better stability than a photoresist composition using a single solvent, and can be better applied to an organic electroluminescent display.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoresist compositions, in particular to a positive photoresist composition with excellent stability. BACKGROUND

[0002] Since the information age, people have developed various flat panel display devices, including thin film transistor liquid crystal display (TFT-LCD), plasma display panel (PDP), electroluminescent device (EL), organic electroluminescent display (OLED), etc.

[0003] At present, although liquid crystal display (LCD) still occupies a dominant position in the display industry, it is difficult to meet the increasing demand for performance and experience of the general public due to the limitations of its structure and materials. Compared with LCD, OLED has many advantages such as high contrast, wide viewing angle, wide color gamut, and lightness, etc., and is favored by people. However, compared with LCD, the process conditions of OLED are more stringent, so there are higher requirements for the stability of photoresist.

[0004] Most of the existing photoresists for TFT-OLED use linear phenolic resin and diazonaphthoquinone (DNQ) system, but the inventors found that when using traditional solvent system (mostly propylene glycol monomethyl ether acetate system), the solubility of the solvent system to the photosensitive compound (PAC) is generally poor, especially when the DNQ content is increased, the PAC is easy to precipitate from the photoresist system, resulting in poor stability of the photoresist, thereby affecting the further testing and production of the photoresist. Therefore, in the field of photoresist compositions, it is an urgent problem for those skilled in the art to develop a photoresist composition with excellent stability, which can be stored for a longer time at a certain temperature and maintain the basic performance. SUMMARY

[0005] The purpose of the present application is to provide a positive photoresist composition with excellent stability to solve the problem of poor stability of photoresist composition under traditional solvent conditions. The specific technical solution is as follows:

[0006] The present application provides a positive photoresist composition, which comprises phenolic resin, photosensitive compound and mixed solvent, wherein the mixed solvent comprises a first solvent and a second solvent, the first solvent is selected from at least one of ethyl lactate, ethyl 3-ethoxypropionate, 4-methyl-2-pentanone and 2-heptanone; the second solvent is selected from at least one of ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether acetate, ethyl acetate and n-butyl acetate.

[0007] In some embodiments of the present application, the content of the first solvent is 3wt%-40wt% and the content of the second solvent is 60wt%-97wt%, based on the total weight of the mixed solvent.

[0008] In some embodiments of the present application, the content of the phenolic resin is 10wt%-20wt%, the content of the photosensitive compound is 2wt%-10wt%, and the content of the mixed solvent is 70wt%-88wt%, based on the total weight of the photoresist composition.

[0009] In some embodiments of the present application, the repeating unit of the phenolic resin is:

[0010]

[0011] The weight average molecular weight of the phenolic resin is 2000-15000, preferably 3000-8000.

[0012] In some embodiments of the present application, the photosensitive compound comprises 0wt%-100wt% of the first photosensitive compound of formula (2) and 0wt%-100wt% of the second photosensitive compound of formula (3), preferably comprises 20wt%-80wt% of the first photosensitive compound of formula (2) and 20wt%-80wt% of the second photosensitive compound of formula (3);

[0013]

[0014] wherein at least two of R1, R2, R3and R4are selected from a group of formula (4) or formula (5), preferably from a group of formula (4); the rest are hydrogen;

[0015] at least two of R5, R6, R7are selected from a group of formula (4) or formula (5), preferably from a group of formula (4); the rest are hydrogen;

[0016]

[0017] R8and R9are each independently selected from C1-C3alkyl, optionally like CH3.

[0018] In some embodiments of the present application, the photoresist composition further comprises an additive, which includes a leveling agent and / or an adhesion promoter, and the content of the additive is 0.1wt%-2.5wt%, based on the total weight of the photoresist composition.

[0019] In some embodiments of the present application, the leveling agent includes an organic silicon-based and / or fluorocarbon compound-based surfactant, and the content of the leveling agent is 0.05wt%-0.5wt%, based on the total weight of the photoresist composition.

[0020] In some embodiments of the present application, the organosilicon surfactant is selected from at least one of polydimethylsiloxane, polycyclo-methylsiloxane, polymethylhydrosiloxane and polymethylphenylsiloxane, and the fluorocarbon surfactant is selected from at least one of perfluoro-octylsulfonyl fluoride, trifluoropropyltriethoxysilane and fluorine-modified acrylate.

[0021] In some embodiments of the present application, the adhesion promoter is selected from at least one of melamine resin and silane coupling agent, and the content of the adhesion promoter is 0.05wt%-2wt% based on the total weight of the photoresist composition.

[0022] Advantages of the present application:

[0023] The photoresist composition provided by the present application, since the solvent system is a mixed solvent containing a first solvent and a second solvent, the solubility of the photosensitive compound (PAC) in the photoresist composition is improved, and the stability thereof is better than that of the photoresist composition using a single solvent, and the photoresist composition can be better applied in OLED displays.

[0024] Of course, implementing any product or method of the present application does not necessarily require achieving all the advantages described above at the same time. DETAILED DESCRIPTION

[0025] The technical solutions in the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0026] The present application provides a positive photoresist composition, which comprises a phenolic resin, a photosensitive compound and a mixed solvent, wherein the mixed solvent comprises a first solvent and a second solvent, the first solvent is selected from at least one of ethyl lactate, ethyl 3-ethoxypropionate, 4-methyl-2-pentanone and 2-heptanone, and the second solvent is selected from at least one of ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether acetate, ethyl acetate and n-butyl acetate, and the second solvent is preferably propylene glycol methyl ether acetate.

[0027] In some embodiments of the present application, the content of the first solvent is 3wt%-40wt%, preferably 3wt%-30wt%, and the content of the second solvent is 60wt%-97wt%, preferably 70wt%-90wt%, based on the total weight of the mixed solvent.

[0028] In some embodiments of the present application, the content of the phenolic resin is 10 wt% to 20 wt%, the content of the photosensitive compound is 2 wt% to 10 wt%, and the content of the mixed solvent is 70 wt% to 88 wt%, based on the total weight of the photoresist composition.

[0029] In some embodiments of the present application, the repeating unit of the phenolic resin is:

[0030]

[0031] The weight average molecular weight of the phenolic resin is 2000 to 15000, preferably 3000 to 8000.

[0032] In some embodiments of the present application, the photosensitive compound in the photoresist composition comprises a first photosensitive compound and a second photosensitive compound, wherein the first photosensitive compound of formula (2) is 0 wt% to 100 wt%, and the second photosensitive compound of formula (3) is 0 wt% to 100 wt%, preferably the first photosensitive compound of formula (2) is 20 wt% to 80 wt%, and the second photosensitive compound of formula (3) is 20 wt% to 80 wt%;

[0033]

[0034] wherein at least two of R1, R2, R3, and R4 are selected from a group of formula (4) or formula (5), preferably from a group of formula (4); the rest is hydrogen;

[0035] at least two of R5, R6, R7 are selected from a group of formula (4) or formula (5), preferably from a group of formula (4); the rest is hydrogen;

[0036]

[0037] R8 and R9 are each independently selected from C1-C3 alkyl, optionally CH3.

[0038] In some embodiments of the present application, the photoresist composition further comprises an additive, wherein the additive comprises a leveling agent and / or an adhesion promoter, and the content of the additive is 0.1 wt% to 2.5 wt%, based on the total weight of the photoresist composition.

[0039] In some embodiments of the present application, the leveling agent comprises an organic silicon-based and / or fluorocarbon compound-based surfactant, and the content of the leveling agent is 0.05 wt% to 0.5 wt%, based on the total weight of the photoresist composition.

[0040] In some embodiments of the present application, the organosilicon surfactant is selected from at least one of polydimethylsiloxane, polycyclo-methylsiloxane, polymethylhydrosiloxane, and polymethylphenylsiloxane, and the fluorocarbon compound surfactant is selected from at least one of perfluoro-octylsulfonyl fluoride, trifluoropropyltriethoxysilane, and fluorine-modified acrylate.

[0041] In some embodiments of the present application, the adhesion promoter is selected from at least one of melamine resin and silane coupling agent, and the content of the adhesion promoter is 0.05 wt% to 2 wt% based on the total weight of the photoresist composition.

[0042] In the present application, the melamine resin can be 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine, and the silane coupling agent can be selected from, but not limited to, at least one of γ-glycidoxypropyltrimethoxysilane, methyltrimethoxysilane, and dimethyldimethoxysilane.

[0043] Hereinafter, the embodiments of the present application are more specifically described by citing examples and comparative examples. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "wt%" are on a weight basis.

[0044] Test methods:

[0045] Photoresist composition stability test:

[0046] The photoresist compositions prepared in each example and comparative example were respectively stored in a 40°C constant-temperature oven and a 5°C-7°C refrigerator, and sampling tests were performed on the 20th day, the 30th day, and the 40th day;

[0047] A photoresist was spin-coated on a silicon wafer, vacuum dried in a vacuum drying oven (VCD), and baked on a hot plate at 110°C for 90s to form a photoresist coating layer, and the coating layer thickness was measured to be about 1.5 μm by a film thickness meter;

[0048] Then, the photoresist layer was exposed to different energies using an exposure machine containing g+h+i wavelengths, and after exposure, the exposed part was removed by drying after developing for 70s using 2.38 wt% tetramethylammonium hydroxide (TMAH) and washing for 25s with water, to form a photoresist pattern.

[0049] Photoresist composition stability evaluation:

[0050] The thickness of the photoresist layer before and after exposure was checked by a film thickness meter, and the residual film rate of the photoresist was calculated;

[0051] The energy at which the exposure and development were just complete was recorded, and the sensitivity of the photoresist was calculated;

[0052] The stability of the photoresist was evaluated according to the sensitivity and the residual film rate.

[0053] Examples

[0054] Example 1

[0055] A linear phenol-formaldehyde resin having a weight average molecular weight of 4000 was 18.8 wt%, a first photosensitive compound was 0.9 wt%, a second photosensitive compound was 3.5 wt%, a leveling agent polydimethylsiloxane was 0.06 wt%, an adhesion promoter melamine resin (2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine) was 1.8 wt%, and the above was dissolved in 75 wt% of a mixed solvent to obtain a photoresist composition.

[0056] The mixed solvent includes ethyl lactate and propylene glycol methyl ether acetate, and the content of ethyl lactate is 10 wt% and the content of propylene glycol methyl ether acetate is 90 wt% based on the total weight of the mixed solvent.

[0057] The first photosensitive compound in this example is a first photosensitive compound represented by formula (2), wherein R1 and R4 are groups represented by formula (4), and R2 and R3 are H; and the second photosensitive compound in this example is a second photosensitive compound represented by formula (3), wherein R5 and R7 are groups represented by formula (5), R6 is H, and R8 and R9 are CH3.

[0058]

[0059] Example 2

[0060] Except that in the mixed solvent, the amount of ethyl lactate is 20 wt% and the content of propylene glycol methyl ether acetate is 80 wt% based on the total weight of the mixed solvent, the rest is the same as Example 1.

[0061] Example 3

[0062] Except that in the mixed solvent, the content of ethyl lactate is 30 wt% and the content of propylene glycol methyl ether acetate is 70 wt% based on the total weight of the mixed solvent, the rest is the same as Example 1.

[0063] Example 4

[0064] Except that in the mixed solvent, the mixed solvent includes 4-methyl-2-pentanone and propylene glycol methyl ether acetate, and the content of 4-methyl-2-pentanone is 3 wt% and the content of propylene glycol methyl ether acetate is 97 wt% based on the total weight of the mixed solvent, the rest is the same as Example 1.

[0065] Example 5

[0066] The same as in Example 1 except that in the mixed solvent, the content of 4-methyl-2-pentanone is 5 wt% and the content of propylene glycol methyl ether acetate is 95 wt% based on the total weight of the mixed solvent.

[0067] Example 6

[0068] The same as in Example 1 except that in the mixed solvent, the content of 4-methyl-2-pentanone is 7 wt% and the content of propylene glycol methyl ether acetate is 93 wt% based on the total weight of the mixed solvent.

[0069] Example 7

[0070] The same as in Example 1 except that in the mixed solvent, the mixed solvent contains ethyl lactate, ethyl 3-methoxypropionate and propylene glycol methyl ether acetate, the content of ethyl lactate is 5 wt%, the content of ethyl 3-methoxypropionate is 5 wt% and the content of propylene glycol methyl ether acetate is 90 wt% based on the total weight of the mixed solvent.

[0071] Example 8

[0072] The same as in Example 1 except that in the mixed solvent, the mixed solvent contains ethyl 3-methoxypropionate, 4-methyl-2-pentanone and propylene glycol methyl ether acetate, the content of ethyl 3-methoxypropionate is 10 wt%, the content of 4-methyl-2-pentanone is 10 wt% and the content of propylene glycol methyl ether acetate is 80 wt% based on the total weight of the mixed solvent.

[0073] Example 9

[0074] The same as in Example 1 except that in the mixed solvent, the mixed solvent contains ethyl lactate and ethylene glycol monomethyl ether, the content of ethyl lactate is 10 wt% and the content of ethylene glycol methyl ether acetate is 90 wt% based on the total weight of the mixed solvent.

[0075] Example 10

[0076] The same as in Example 1 except that in the mixed solvent, the mixed solvent contains ethyl lactate, propylene glycol monoether acetate and ethylene glycol monomethyl ether, the content of ethyl lactate is 10 wt%, the content of propylene glycol monoether acetate is 45 wt% and the content of ethylene glycol monomethyl ether is 45 wt% based on the total weight of the mixed solvent.

[0077] Example 11

[0078] The same as in Example 1 except that in the photoresist composition, the leveling agent in the additive is a fluorine-modified acrylate.

[0079] Example 12

[0080] The rest is the same as Example 1 except that in the photoresist composition, the adhesion promoter in the additive is a silane coupling agent (γ-glycidoxypropyltrimethoxysilane).

[0081] Example 13

[0082] The rest is the same as Example 1 except that in the photoresist composition, only polydimethylsiloxane is a leveling agent, and no other additives are contained.

[0083] Example 14

[0084] The rest is the same as Example 1 except that in the photoresist composition, only melamine resin (2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine) is an adhesion promoter, and no other additives are contained.

[0085] Comparative Example 1

[0086] The rest is the same as Example 1 except that in the photoresist composition, the solvent is propylene glycol monomethyl ether acetate used alone.

[0087] Comparative Example 2

[0088] The rest is the same as Example 1 except that in the photoresist composition, the solvent is ethylene glycol monomethyl ether used alone.

[0089] The preparation parameters of each example and comparative example are shown in Table 1.

[0090] The performance test results of each example and comparative example are shown in Table 2.

[0091]

[0092]

[0093]

[0094]

[0095] As can be seen from Table 2, compared with storage at 5-7°C, the sensitivity and residual film rate of Comparative Example 1 at 40°C become more and more different from the measurement results at 20 days as time goes on, and the stability is poor; from Example 1-Example 8 and Comparative Example 1, it can be seen that the sensitivity and residual film rate of the photoresist composition of the present application change less at different temperatures and times, so that by mixing different solvents, the stability of the photoresist of the present application is better than that of the photoresist using a single solvent; from Example 1-Example 3 and Comparative Example 1, it can be seen that compared with Comparative Example 1, the sensitivity of the photoresist composition of the present application is more similar, and compared with using other solvent mixtures, the sensitivity is faster, and the actual production demand can be better met.

[0096] From Example 9 and Comparative Example 2, it can be seen that the photoresist composition prepared by using a single solvent in Comparative Example 2 has a greater difference in sensitivity and residual film rate at 40°C over time compared with the test results at 20 days, has poor stability, and the sensitivity reaches 40 mj / cm 2 In actual production, the above affects the production capacity; Example 9 is a mixed system of two solvents, and the sensitivity and residual film rate change little at different temperatures and times.

[0097] In Examples 11-13, the ratio of the mixed solvents is the same as in Example 1, the ratio of the first photosensitive compound to the second photosensitive compound in the photosensitive compound is changed, and the ratio of the first photosensitive compound is increased. At 5°C-7°C for different times, the sensitivity and residual film rate change little. At 40°C for different times, the sensitivity and residual film rate also change little. After increasing the ratio of the first photosensitive compound, the sensitivity is increased, and within a certain range, faster sensitivity will improve production capacity. In Examples 11-13, the sensitivity varies between 26 mj / cm 2 -30 mj / cm 2 , which can meet the exposure range of the exposure machine on the production line. In combination of Example 1 and Examples 11-14, the photoresist composition with the content of the photosensitive compound within the preferred range of the present application has better stability.

[0098] In Example 14, the photosensitive agent and the solvent system are the same as in Example 1, and no organic silicon or fluorocarbon surfactant leveling agent is added, which causes the photoresist to have a non-uniform film thickness (Mura) after coating, which is not conducive to the subsequent exposure and development process. From Example 1 and Example 14, it can be seen that the photoresist compound further added with a leveling agent and an adhesion promoter can have better stability.

[0099] The above only describes the preferred embodiments of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application is included in the protection scope of the present application.

Claims

1. A positive photoresist composition comprising a phenol-aldehyde resin, a photosensitive compound, and a mixed solvent, wherein, The mixed solvent comprises a first solvent selected from at least one of ethyl lactate, ethyl 3-ethoxypropionate, 4-methyl-2-pentanone, and 2-heptanone; and a second solvent selected from at least one of ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether acetate, ethyl acetate, and n-butyl acetate; the phenolic resin has a repeating unit of: ； The phenolic resin has a weight average molecular weight of 2000-15000; The photosensitive compound comprises 20wt%-80wt% of a first photosensitive compound of formula (2) and 20wt%-80wt% of a second photosensitive compound of formula (3); At least two of R1, R2, R3, and R4 are selected from a group of formula (4); the rest are hydrogen; At least two of R5, R6, and R7 are selected from a group of formula (4) or formula (5); the rest are hydrogen; R8 and R9 are each independently selected from CH3.

2. The photoresist composition of claim 1, wherein, The content of the first solvent is 3wt%-40wt% and the content of the second solvent is 60wt%-97wt% based on the total weight of the mixed solvent.

3. The photoresist composition of claim 1, wherein, The content of the phenolic resin is 10wt%-20wt%, the content of the photosensitive compound is 2wt%-10wt%, and the content of the mixed solvent is 70wt%-88wt% based on the total weight of the photoresist composition.

4. The photoresist composition of claim 1, wherein, The phenolic resin has a weight average molecular weight of 3000-8000.

5. The photoresist composition of claim 1, wherein, At least two of R1, R2, R3, and R4 are selected from a group of formula (4); the rest are hydrogen; At least two of R5, R6, and R7 are selected from a group of formula (4); the rest are hydrogen; R8 and R9 are each independently selected from CH3.

6. The photoresist composition of claim 1, further comprising an additive, the additive including a leveling agent and / or an adhesion promoter, the content of the additive being 0.1wt%-2.5wt% based on the total weight of the photoresist composition.

7. The photoresist composition of claim 6, wherein, The leveling agent includes a silicone-based and / or fluorocarbon compound-based surfactant, the content of the leveling agent being 0.05wt%-0.5wt% based on the total weight of the photoresist composition.

8. The photoresist composition of claim 7, wherein, The silicone-based surfactant is selected from at least one of polydimethylsiloxane, polycyclo-methylsiloxane, polymethylhydrogenosiloxane, and polymethylphenylsiloxane, and the fluorocarbon compound-based surfactant is selected from at least one of perfluoro-octylsulfonyl fluoride, trifluoropropyltriethoxysilane, and fluorine-modified acrylate.

9. The photoresist composition of claim 6, wherein, The adhesion promoter is selected from at least one of melamine resin and silane coupling agent, the content of the adhesion promoter being 0.05wt%-2wt% based on the total weight of the photoresist composition.

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