A fluorine-containing novolak resin, a method for preparing the same, and a photoresist composition using the same

Abstract

The present application relates to phenolic resin and its application in the field of liquid crystal and organic electroluminescent display technology, specifically relates to a kind of fluorine-containing phenolic resin and its preparation method and the photoresist composition using it.The present application provides a kind of fluorine-containing phenolic resin, the molecular weight of the fluorine-containing phenolic resin is 3000-15000, the fluorine-containing phenolic resin has the structure as shown in structural formula (A), and at least one fluorine substituent group is carried in any position on non-hydroxyl group in formula (A).The fluorine-containing phenolic resin of the present application has high alkali dissolution rate, the existence of C-F bond improves the rigidity of molecular chain while having certain hydrophobicity, so that the photoresist comprising the present fluorine-containing phenolic resin is enhanced in non-exposed area dissolution inhibition, beneficial to improve residual film rate and image resolution.

Description

Technical Field

[0001] This invention relates to phenolic resins and their applications in the fields of liquid crystal and organic electroluminescent display technology, specifically to a fluorinated phenolic resin, its preparation method, and a photoresist composition using the same. Background Technology

[0002] Positive photoresist is used in the TFT (thin-film transistor) fabrication process of LCD and OLED (organic light-emitting diode) panels to protect etched circuitry. With the development of panel technology, TFT photoresist is evolving towards higher sensitivity and higher resolution. High-sensitivity photoresist generally has a lower molecular weight and a higher density of hydrophilic groups, resulting in poorer residual film yield. Insufficient photoresist residual film yield leads to deterioration in pattern resolution and etching pattern morphology, affecting product yield. Summary of the Invention

[0003] The problem this invention aims to solve is that, in order to further meet the requirements for high sensitivity, high resolution, and high film retention of thin-film transistor (TFT) photoresists, it is urgent to develop new photoresist compositions in order to obtain high-performance TFT liquid crystal panels or OLED panels.

[0004] In order to solve the problems in the prior art, the inventors devoted themselves to research and found that adding fluorinated phenolic resin as an essential component to the photoresist composition can ensure high sensitivity and high resolution while ensuring high film retention rate.

[0005] Specifically, the present invention provides a fluorinated phenolic resin with a molecular weight of 3000-15000. The fluorinated phenolic resin is a random copolymer having the structure shown in formula (A) composed of monomers with structures shown in formulas (I), (II), and (III), and in formula (A) it has at least one fluorinated substituent at any position on the non-hydroxyl group.

[0006]

[0007] In equation (A), M represents the structure shown in equation (I), and Q represents the structure shown in equation (II):

[0008]

[0009] In formula A, R 13 Selected from hydrogen, substituted or unsubstituted C1-C18 aliphatic hydrocarbon groups; n1 and n2 are independent integers greater than 1 and less than 100, and the value of n1 / (n1+n2) is between 0.1 and 0.5;

[0010] In formula (I), R1-R5 and Ra-Re are each independently selected from hydrogen, hydroxyl, substituted or unsubstituted C1-C30 aliphatic groups, and halogen atoms; R6 and R7 are each independently selected from hydrogen, substituted or unsubstituted C1-C30 aliphatic groups, substituted or unsubstituted C6-C60 aromatic groups, and halogen atoms; R8 is a single bond, substituted or unsubstituted C1-C30 aliphatic groups, substituted or unsubstituted C6-C60 aromatic groups; R9 and R... 10 Each is independently selected from hydrogen, substituted or unsubstituted C1-C30 aliphatic groups, substituted or unsubstituted C6-C60 aromatic groups, or halogen atoms;

[0011] Furthermore, at least one of R1-R5 is a hydroxyl group, or at least one of Ra-Re is a hydroxyl group; R6 and R7 are not simultaneously substituted or unsubstituted C6-C60 aromatic groups; and R9 and R... 10 Not simultaneously substituted or unsubstituted C6-C60 aromatic groups;

[0012] In equation (II), R 11 R 12 Each is independently selected from hydrogen, substituted or unsubstituted C1-C30 aliphatic hydrocarbon groups, and hydroxyl groups;

[0013] The substituent groups on the substituted aliphatic and substituted aromatic groups are each independently selected from one of the following: halogen, C1-C10 chain alkyl, C3-C10 cycloalkyl, C6-C30 aryl, and C3-C30 heteroaryl.

[0014] It should be noted that, in the fluorinated phenolic resin structure of the present invention, there is no particular limitation on the position of the connection sites of the two structural units of formula (I) and formula (II) on the polymer chain of formula (A). That is, the fluorinated phenolic resin of the present invention is a random copolymer, as long as R1-R 13 If Ra-Re and n1-n2 satisfy the above-described range, the inventive purpose and technical effect of this invention can be achieved.

[0015] The fluorinated phenolic resin of the present invention adopts the structure of formula (A), in which at least one fluorine substituent is present at any position on the non-hydroxyl group in formula (A). The presence of CF bonds improves the rigidity of the molecular chain and has a certain degree of hydrophobicity. Therefore, the fluorinated phenolic resin of the present invention has a high alkali dissolution rate, thereby ensuring that the photoresist prepared by the fluorinated phenolic resin of the present invention achieves enhanced dissolution inhibition in non-exposure areas, which is beneficial to improving the residual film rate and image resolution.

[0016] Among them, "alkali dissolution rate" refers to the dissolution rate of the photoresist composition in alkaline developer; "residual film rate" refers to the ratio of the film thickness after development in the non-exposed area to the film thickness before development. The higher the residual film rate, the more resistant the photoresist composition is to washing; "image resolution" refers to the smallest pattern size that the photoresist can obtain.

[0017] In this invention, the description of chemical elements includes the concept of isotopes with the same chemical properties, such as the description of "hydrogen", as well as the concepts of "deuterium" and "tritium" with the same chemical properties.

[0018] Hydrocarbons are a general term for compounds composed of carbon and hydrogen atoms, mainly including alkanes, cycloalkanes, alkenes, alkynes, and aromatic hydrocarbons. A hydrocarbon group is a group containing only carbon and hydrogen atoms, generally referring to the group remaining after a hydrocarbon compound loses a hydrogen atom (H). Different types of hydrocarbon groups can be obtained from different hydrocarbons. Hydrocarbon groups can be classified as monovalent, divalent, and trivalent. For example, monovalent groups include: CH3CH2- (ethyl), (isopropyl), CH≡C-CH2- (2-propynyl); divalent groups include: CH3CH= (ethylene), -CH=CH- (1,2-vinylene); and trivalent groups include: CH3C≡ (ethene).

[0019] In this specification, hydrocarbon groups include aliphatic hydrocarbon groups and aromatic hydrocarbon groups. Specifically, aliphatic hydrocarbon groups are hydrocarbon groups formed by removing one or more hydrogen atoms from an aliphatic hydrocarbon molecule. Aliphatic hydrocarbon groups can be further divided into alkyl, alkenyl, and alkynyl groups. For example: CH3-methyl (alkyl), CH2=CH-vinyl (alkenyl), CH≡C-ethynyl (alkynyl). Methyl, ethyl, n-propyl, and isopropyl are some of the most common hydrocarbon groups. Aliphatic hydrocarbon groups are hydrocarbon groups formed by removing one or more hydrogen atoms from the nucleus of an aromatic hydrocarbon, such as phenyl C6H5-.

[0020] In this invention, the preferred C1-C30 aliphatic groups include: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, sec-pentyl, neopentyl, n-hexyl, neohexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-dodecyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl, vinyl, propenyl, and butenyl; the preferred C6-C60 aromatic groups include: phenyl, naphthyl, anthracene, benzanthracene, phenanthryl, benzo[a]phenanthryl, pyrene, peryl, and fluoranthracene. Biphenyl, azophenyl, terphenyl, triphenyl, fluorenyl, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, 2-biphenyl, 3-biphenyl and 4-biphenyl, p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, m-terphenyl-4-yl, m-terphenyl-3-yl, m-terphenyl-2-yl, 1-naphthyl, 2-naphthyl, 1-anthrayl, 2-anthrayl, 9-anthrayl, 1-fluorenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl, 9-fluorenyl, 1-pyrene, 2-pyrene, 4-pyrene, etc.

[0021] In the fluorinated phenolic resin of the present invention as shown in general formula (A), the molecular weight is 3000-15000. If the molecular weight of the fluorinated phenolic resin is too high, the alkali dissolution rate will decrease and the photosensitivity of the photoresist composition will decrease. If the molecular weight is too low, it will be difficult to achieve the effects of heat resistance and development performance.

[0022] In the structure (I) of the present invention, the number of hydroxyl groups in R1-R5 is preferably 1-3, most preferably 1, wherein the hydroxyl groups are preferably located at the ortho and para positions of C6 and R7, and preferably, at least one of R1, R3 and R4 is a hydroxyl group. The number of aliphatic groups in R1-R5 is preferably 1-2, and the aliphatic group is preferably methyl. R6 and R7 are preferably hydrogen, methyl or halogen atoms, and R8 is preferably a single bond or a C6-C60 aromatic group, wherein the aromatic group is preferably phenyl, naphthyl, anthracene, benzanthracene, phenanthrene, benzo[a]phenanthrene, pyrene, peryl, fluoranthracene, biphenyl, amphoteric, terphenyl, etc. a -R e The number of hydroxyl groups is preferably 1-3, most preferably 1, wherein the aliphatic hydrocarbon groups are preferably located at R9, R... 10 The adjacent and opposite positions of C, preferably R a R c and R e At least one of them is a hydroxyl group. R a -R e The number of aliphatic hydrocarbon groups is preferably 1-2, and the aliphatic hydrocarbon group is preferably methyl. R9, R 10 Preferably, it contains hydrogen, methyl, or halogen atoms.

[0023] Structure (I) is preferably a structure containing fluorine substituents, which can be located in the R1-R1 range. 10 R a -R e Any position on the non-hydroxyl group in it.

[0024] The structure (I) of the present invention may be selected from, but is not limited to, the following structures:

[0025]

[0026]

[0027]

[0028] In structural formula (II) of this invention, R 11 and R 12 If hydrogen is preferred, then structural formula (II) is 2,5-dimethylphenol or 3,5-dimethylphenol or a mixture of both.

[0029] In structural formula (III) of this invention, R 13The group is hydrogen, substituted or unsubstituted hydrocarbon group, and the structural formula (III) can be one of formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, hexanal, trichloroacetaldehyde, furfural, glyoxal, allylaldehyde, benzaldehyde, crotonaldehyde, o-tolualdehyde, salicylaldehyde, etc., preferably formaldehyde.

[0030] The second objective of this invention is to provide a photoresist composition with fluorinated phenolic resin as one of the essential components, characterized in that the photoresist composition comprises the above-mentioned fluorinated phenolic resin A, fluorine-free phenolic resin, photosensitizer, solvent and additives;

[0031] Further preferred options may include sensitivity modifiers and crosslinking agents.

[0032] Those skilled in the art can adjust the proportions of each component in the photoresist composition as needed. With the total weight of the photoresist composition as 100%, the weight content of each component in the photoresist composition is as follows: photosensitizer 1-5%; fluorine-free phenolic resin 6-11%; solvent 75-93%; additives 0.01-0.5%; fluorine-containing phenolic resin A: 2.5-7%.

[0033] Furthermore, the proportions of each component in the photoresist composition can be adjusted as needed, and in addition to the above components, 0.1-1% of a sensitivity modifier and 0.1-2% of a crosslinking agent can be added.

[0034] In the above-described photoresist composition of the present invention, the photosensitizer is a diazonoquinone photosensitizer well known to those skilled in the art, such as a disubstituted ester compound of diazonoquinone sulfonyl chloride and trihydroxybenzophenone, or a trisubstituted ester compound of diazonoquinone sulfonyl chloride and tetrahydroxybenzophenone.

[0035] In the photoresist composition of the present invention, the fluorine-free phenolic resin is well known to those skilled in the art and is polymerized from phenolic compounds and aldehyde compounds. For example, resins polymerized from the following phenolic compounds and aldehyde compounds can be selected: phenolic hydroxyl compounds can be selected from one or more of phenol, cresol, xylenol, ethylphenol, propionic acid, butylphenol, tert-butylphenol, di-tert-butylphenol, octylphenol, fluorophenol, chlorophenol, bromophenol, iodophenol, naphthol, anthraquinone, dihydroxybenzene, dihydroxynaphthalene, biphenol, bisphenol, aminophenol, nitrophenol, phloroglucinol, etc. Aldehyde compounds can be selected from one or more of formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, hexanal, trichloroacetaldehyde, furfural, glyoxal, allylaldehyde, benzaldehyde, crotonaldehyde, o-tolualdehyde, salicylaldehyde, etc. More specifically, it can be linear phenolic resins polymerized from cresol and formaldehyde, linear phenolic resins polymerized from xylenol and formaldehyde, linear phenolic resins polymerized from di-tert-butylphenol and formaldehyde, linear phenolic resins polymerized from dihydroxynaphthalene and formaldehyde, linear phenolic resins polymerized from phloroglucinol and formaldehyde, linear phenolic resins polymerized from xylenol, formaldehyde, and salicylaldehyde, etc.

[0036] In the photoresist composition of the present invention, the solvent is well known to those skilled in the art, and may be selected from one or more of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol butyl methyl ether, diethylene glycol butyl ethyl ether, diethylene glycol diethyl ether ethyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol butyl methyl ether, dipropylene glycol ethylhexyl ether, triethylene glycol dimethyl ether, triethylene glycol tert-butyl ether, chloroform, xylene, ethyl lactate, γ-butyrolactone, N-methylpyrrolidone, benzyl alcohol, and dimethyl sulfoxide.

[0037] In the photoresist composition of the present invention, in order to improve the coating performance of the photoresist composition, some additives can be selected, such as one or more selected from leveling agents, defoamers, coupling agents, and ultraviolet absorbers. Specifically, additives of types and amounts well known to those skilled in the art can be selected. For example, the leveling agent can be selected from acrylic leveling agents, silane leveling agents, and fluorinated leveling agents. The defoamer can be selected from silicone defoamers, polyether defoamers, and polyether-modified polysiloxane defoamers. The coupling agent can be selected from trimethoxysilylbenzoic acid, vinyltrimethoxysilane, vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-isocyanate propyltriethoxysilane, γ-glycidylpropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. The ultraviolet absorber can be selected from 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, phenyl oxobenzoate, 2,4-dihydroxybenzophenone, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, etc.

[0038] Furthermore, the photoresist composition of the present invention may also include a sensitivity modifier, which is a small molecule compound known to those skilled in the art that can improve sensitivity, specifically a small molecule phenolic resin, phenol, naphthol, methylphenol, dimethylphenol, trihydroxybenzophenone, tetrahydroxybenzophenone, etc.

[0039] Furthermore, the photoresist composition of the present invention may also include a crosslinking agent, which is well known to those skilled in the art, including amino-based crosslinking agents, epoxy-based crosslinking agents, ether-based crosslinking agents, urea-based crosslinking agents, etc. Specifically, it may include hexamethylenetetramine, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 1,4-butanediol diglycidyl ether, hexamethylenemethyl melamine, trialkoxycarbonylaminotriazine 1,3-di(methoxymethyl)-4,5-dimethoxy-2-imidazolium ketone, etc.

[0040] A third objective of this invention is to provide a method for preparing the above-mentioned fluorinated phenolic resin, comprising: under reaction conditions with an organic acid as a catalyst, contacting monomers with structures shown in formulas (I), (II), and (III) to each other for copolymerization to obtain the fluorinated phenolic resin as described in any one of claims 1-5:

[0041]

[0042] Preferably, the copolymerization reaction includes: heating and stirring in a water bath, refluxing the reaction mixture for 1-5 hours (which can be 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours), stirring until homogeneous, cooling to room temperature and separating the water layer, then distilling the reaction solution under reduced pressure and slowly heating it to 120℃-170℃ (which can be 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, or 170℃), and maintaining this temperature for 0.5-3 hours (which can be 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours) to remove residual moisture;

[0043] More preferably, the copolymerization reaction includes: heating and stirring in a water bath, refluxing the reaction mixture for 3 hours, stirring until homogeneous, cooling to room temperature and separating the water layer, then distilling the reaction solution under reduced pressure and slowly heating it to 150°C for 1 hour to remove residual moisture.

[0044] The fourth objective of this invention is to provide the application of the above-mentioned fluorinated phenolic resin and the above-mentioned photoresist composition in the fabrication of thin film transistors (TFTs).

[0045] The beneficial effects of this invention are as follows: The fluorinated phenolic resin of this invention has a high alkali dissolution rate. The presence of CF bonds increases the rigidity of the molecular chain and also has a certain degree of hydrophobicity, which enhances the dissolution inhibition of the photoresist composed of this resin in the non-exposed area, thus improving the residual film rate and image resolution. Attached Figure Description

[0046] Figure 1 This is a scanning electron microscope (SEM) image of the slope angle (taper) morphology of the photoresist composition prepared in Example 1 of the present invention after development and baking;

[0047] Figure 2 This is a SEM image of the slope angle (taper) morphology of the photoresist composition prepared in Comparative Example 1 of the present invention after development and baking. Detailed Implementation

[0048] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. Unless otherwise specified, in the following embodiments and comparative examples, temperatures are in Celsius, and parts and percentages are by weight.

[0049] Preparation Example 1

[0050] The phenolic resin A was prepared using an acid catalyst via a one-step synthesis. 36.24 g of compound (12), 18.3 g of 2,5-dimethylphenol, 13.8 g of 37% formaldehyde aqueous solution, 2.5 ml of deionized water, and 0.8 g of hydrated oxalic acid were added to a three-necked flask equipped with a mechanical stirrer, reflux condenser, and thermometer. The mixture was heated in a water bath with stirring, and the reaction mixture was refluxed for 3 hours. 90 ml of deionized water was added, and the mixture was stirred until homogeneous. The mixture was then cooled to room temperature, and the aqueous layer was separated. The reaction solution was distilled under reduced pressure and slowly heated to 150°C, maintaining this temperature for 1 hour to remove residual moisture. The product was cooled to room temperature to obtain a brittle solid with a weight-average molecular weight of 5000. The molecular weight was determined by gel permeation chromatography.

[0051] Preparation Example 2

[0052] 17.16 g of compound (3), 18.3 g of 2,5-dimethylphenol, 13.8 g of 37% formaldehyde aqueous solution, 2.5 ml of deionized water, and 0.5 g of hydrated oxalic acid were added to a three-necked flask equipped with a mechanical stirrer, reflux condenser, and thermometer. The mixture was heated in a water bath with stirring, and the reaction mixture was refluxed for 3 h. 90 ml of deionized water was added, and the mixture was stirred until homogeneous. The mixture was then cooled to room temperature, and the aqueous layer was separated. The reaction solution was distilled under reduced pressure and slowly heated to 150 °C, and held for 1 h to remove residual moisture. The product was cooled to room temperature to obtain a brittle solid with a weight-average molecular weight of 4000. The molecular weight was determined by gel permeation chromatography.

[0053] Preparation Example 3

[0054] 23.4 g of compound (4), 18.3 g of 2,5-dimethylphenol, 13.8 g of 37% formaldehyde aqueous solution, 2.5 ml of deionized water, and 0.6 g of hydrated oxalic acid were added to a three-necked flask equipped with a mechanical stirrer, reflux condenser, and thermometer. The mixture was heated in a water bath with stirring, and the reaction mixture was refluxed for 3 hours. 90 ml of deionized water was added, and the mixture was stirred until homogeneous. The mixture was then cooled to room temperature, and the aqueous layer was separated. The reaction solution was distilled under reduced pressure and the temperature was slowly raised to 150 °C and maintained for 1 hour to remove residual moisture. The product was cooled to room temperature to obtain a brittle solid with a weight-average molecular weight of 4500. The molecular weight was determined by gel permeation chromatography.

[0055] Preparation Example 4

[0056] 41.04 g of compound (13), 18.3 g of 2,5-dimethylphenol, 13.8 g of 37% formaldehyde aqueous solution, 2.5 ml of deionized water, and 0.9 g of hydrated oxalic acid were added to a three-necked flask equipped with a mechanical stirrer, reflux condenser, and thermometer. The mixture was heated in a water bath with stirring, and the reaction mixture was refluxed for 3 hours. 90 ml of deionized water was added, and the mixture was stirred until homogeneous. The mixture was then cooled to room temperature, and the aqueous layer was separated. The reaction solution was distilled under reduced pressure and slowly heated to 150 °C, maintaining the temperature for 1 hour to remove residual moisture. The product was cooled to room temperature to obtain a brittle solid with a weight-average molecular weight of 5300. The molecular weight was determined by gel permeation chromatography.

[0057] Preparation Example 5

[0058] The difference between Preparation Example 5 and Preparation Example 1 is that the heating reflux time in Preparation Example 5 is 2 hours, and a brittle solid with a weight-average molecular weight of 3900 is finally obtained. The molecular weight is determined by gel permeation chromatography.

[0059] Preparation Example 6

[0060] The difference between Preparation Example 6 and Preparation Example 1 is that the heating reflux time of Preparation Example 5 was 4 hours, and a brittle solid with a weight-average molecular weight of 7000 was finally obtained. The molecular weight was determined by gel permeation chromatography.

[0061] Example 1

[0062] The fluorinated phenolic resin A obtained in Preparation Example 1 above was combined with propylene glycol monomethyl ether acetate (PMA, as a solvent), a fluorine-free phenolic resin (linear phenolic resin, Shengquan 8850), a photosensitizer (Toyo PAC350), a silane coupling agent (γ-glycidyl ether propyltrimethoxysilane), and a fluorinated leveling agent (Dow Corning DC-7) to form a photoresist composition. The specific composition and content are shown in Table 1.

[0063] Example 2

[0064] The difference between Example 2 and Example 1 is that Example 2 uses the phenolic resin prepared in Preparation Example 2 to formulate a photoresist composition.

[0065] Example 3

[0066] The difference between Example 3 and Example 1 is that Example 3 uses the phenolic resin prepared in Example 3 to form a photoresist composition.

[0067] Example 4

[0068] The difference between Example 4 and Example 1 is that Example 4 uses the phenolic resin prepared in Example 4 to form a photoresist composition.

[0069] Example 5

[0070] The difference between Example 5 and Example 1 is that Example 5 uses the phenolic resin prepared in Example 5 to form a photoresist composition.

[0071] Example 6

[0072] The difference between Example 6 and Example 1 is that Example 6 uses the phenolic resin prepared in Example 6 to form a photoresist composition.

[0073] Comparative Example 1

[0074] Comparative Example 1 is similar to Example 1, except that a fluorine-free phenolic resin (Asahi Organic 40B40G) with a similar molecular weight is used in Comparative Example 1 instead of the fluorine-containing phenolic resin in Preparation Example 1.

[0075] Comparative Example 2

[0076] Comparative Example 2 is similar to Example 1, except that Comparative Example 2 uses a phenolic resin (Asahi Organic 6050G) with a similar molecular weight that is free of fluorine and does not contain structural (II) structural units instead of the fluorinated phenolic resin in Preparation Example 1.

[0077] Test case

[0078] The photoresist compositions prepared in Examples 1-6 and Comparative Examples 1-2 were subjected to photolithography experiments under the same conditions, specifically including the following steps:

[0079] First, a glass substrate was prepared, irradiated with a UV cleaner for 1 minute, and cleaned with deionized water. Then, the photoresist composition was uniformly coated onto the glass substrate surface by spin coating. After pre-baking at 110°C for 140 seconds, a 1.5 μm thick film was obtained. Exposure was performed using 365 nm UV light with the mask at 0 μm distance from the coating. Development was carried out with 2.38% TMAH (tetramethylammonium hydroxide) solution at 23°C for 40 seconds, followed by rinsing with water and drying. After development, the substrate was baked at 130°C for 120 seconds, and the exposure amount and residual film yield were measured.

[0080] Exposure amount is an indicator for evaluating the sensitivity of photoresist, referring to the exposure amount required to resolve a 1:1 pattern under a photomask with an L / S ratio of 1:1. This exposure amount can be adjusted according to requirements and cannot be used to judge the performance of the photoresist composition. Residual film rate is an indicator for evaluating the wash resistance of photoresist. It can be measured using an ellipsometry to measure the film thickness before and after development, and the ratio of the film thickness after development to the film thickness before development is calculated as the residual film rate. In this invention, the performance of the photoresist composition is judged by the residual film rate. The specific experimental results of Examples 1-6 and Comparative Examples 1 and 2 are detailed in Table 1 below.

[0081] Table 1:

[0082]

[0083]

[0084] As shown in Table 1, the photoresist compositions prepared in Examples 1-6 of the present invention all exhibit relatively higher residual film rates compared with the photoresist compositions prepared in Comparative Examples 1-2, indicating that they have better practical performance.

[0085] Specifically, the only difference between Example 1 and Comparative Example 1 is that Example 1 incorporates the fluorinated phenolic resin provided by this invention, while Comparative Example 1 uses a non-fluorinated phenolic resin. It can be seen that the photoresist composition prepared in Example 1 shows a significantly improved residual film yield compared to Comparative Example 1; furthermore, from... Figure 1 and Figure 2 It can also be seen that, compared to Comparative Example 1, Example 1 has a better pattern morphology, indicating improved resolution. This demonstrates that the photoresist composition of the present invention is beneficial for improving residual film yield and resolution.

[0086] The only difference between Example 1 and Comparative Example 2 is that Example 1 incorporates the fluorinated phenolic resin provided by this invention, while Comparative Example 2 uses a fluorinated phenolic resin that does not contain the structural unit of formula (II). It can be seen that the photoresist composition prepared in Example 1 has a significantly improved residual film yield compared to Comparative Example 2, indicating that the dimethylphenol structural unit of structure (II) in the fluorinated phenolic resin structure of this invention also has a beneficial effect on improving the residual film yield.

[0087] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A fluorinated phenolic resin for positive photoresist, which is a random copolymer having the structure shown in formula (A) prepared from monomers with structures shown in formula (I), formula (II) and formula (III), wherein the molecular weight of the fluorinated phenolic resin is 3000-15000. （A） In equation (A), M represents the structure shown in equation (I), and Q represents the structure shown in equation (II). Equation (I) is selected from the following structure: ； Formula (II) is 2,5-dimethylphenol, 3,5-dimethylphenol, or a mixture of 2,5-dimethylphenol and 3,5-dimethylphenol; Formula (III) is selected from one of formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, hexanal, benzaldehyde, and o-toluene formaldehyde.

2. The fluorinated phenolic resin for positive photoresist according to claim 1, characterized in that, Formula (III) is selected from formaldehyde.

3. A method for preparing a fluorinated phenolic resin for positive photoresist, comprising: Under reaction conditions catalyzed by organic acids, the monomers represented by formulas (I), (II), and (III) are brought into contact with each other to undergo a copolymerization reaction, thereby obtaining the fluorinated phenolic resin according to claim 1 or 2: Equation (I) is selected from the following structure: Formula (II) is 2,5-dimethylphenol, 3,5-dimethylphenol, or a mixture of 2,5-dimethylphenol and 3,5-dimethylphenol; Formula (III) is selected from one of formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, hexanal, benzaldehyde, and o-toluene formaldehyde.

4. The method for preparing fluorinated phenolic resin for positive photoresist according to claim 3, characterized in that, The copolymerization reaction includes: heating and stirring in a water bath, refluxing the reaction mixture for 1-5 hours, cooling to room temperature after stirring evenly and separating the water layer, distilling the reaction solution under reduced pressure and slowly heating to 120℃-170℃, maintaining for 0.5-3 hours to remove residual moisture.

5. The method for preparing fluorinated phenolic resin for positive photoresist according to claim 3, characterized in that, The copolymerization reaction includes: heating and stirring in a water bath, refluxing the reaction mixture for 3 hours, stirring until homogeneous, cooling to room temperature and separating the water layer, then distilling the reaction solution under reduced pressure and slowly heating it to 150°C for 1 hour to remove residual moisture.

6. A positive photoresist composition, comprising the fluorinated phenolic resin for positive photoresist as described in claim 1 or 2, a fluorine-free phenolic resin, a photosensitizer, a solvent, and an additive, wherein the weight percentage content of each component is as follows: Photosensitizer: 1-5%; Fluorine-free phenolic resin: 6-11%; Solvent: 75-93%; Additives: 0.01-0.5%; Fluorinated phenolic resin: 2.5-7%; The sum of the amounts of all components meets the requirement of 100%; The additives are selected from one or more combinations of leveling agents, defoamers, coupling agents, and ultraviolet absorbers.

7. The positive photoresist composition according to claim 6, characterized in that, The photosensitizer is selected from disubstituted ester compounds of diazononaphthoquinone sulfonyl chloride and trihydroxybenzophenone, and trisubstituted ester compounds of diazononaphthoquinone sulfonyl chloride and tetrahydroxybenzophenone. The fluorine-free phenolic resin is selected from linear phenolic resins polymerized from cresol and formaldehyde, linear phenolic resins polymerized from xylenol and formaldehyde, linear phenolic resins polymerized from di-tert-butylphenol and formaldehyde, linear phenolic resins polymerized from dihydroxynaphthalene and formaldehyde, linear phenolic resins polymerized from phloroglucinol and formaldehyde, linear phenolic resins polymerized from xylenol and formaldehyde, and linear phenolic resins polymerized from salicylaldehyde. The solvent is selected from one or more of the following: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol butyl methyl ether, diethylene glycol butyl ethyl ether, diethylene glycol diethyl ether ethyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol butyl methyl ether, dipropylene glycol ethylhexyl ether, triethylene glycol dimethyl ether, triethylene glycol tert-butyl ether, chloroform, xylene, ethyl lactate, γ-butyrolactone, N-methylpyrrolidone, benzyl alcohol, and dimethyl sulfoxide.

8. The use of the positive photoresist composition of claim 7 in the fabrication of thin-film transistors.

9. The use of the fluorinated phenolic resin for positive photoresist as described in claim 1 in the fabrication of thin-film transistors.

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