Photoresist composition and photolithography process

Abstract

The application discloses a photoresist composition and a photoetching process, and belongs to the photoetching technical field.The photoresist composition comprises the following components: high-molecular-weight phenolic resin, low-molecular-weight phenolic resin, diazonaphthoquinone photosensitizer, phenolic hydroxyl compound and solvent, wherein the molecular weight of the high-molecular-weight phenolic resin is greater than or equal to 10000, the molecular weight of the low-molecular-weight phenolic resin is less than or equal to 4000, and the mass ratio of the high-molecular-weight phenolic resin to the low-molecular-weight phenolic resin is 0.1-9:1.The photoresist composition provided by the embodiment of the application can have improved low exposure energy and high resolution, high film retention rate, excellent substrate adhesion and film thickness uniformity.

Description

Technical Field

[0001] This invention relates to the field of photolithography, and particularly to photoresist compositions and photolithography processes. Background Technology

[0002] Photoresist is a photosensitive hybrid material that is typically used to create fine patterns through photolithography.

[0003] The optimal exposure energy (Eop) of photoresist refers to the exposure energy required to replicate a pattern at a 1:1 scale. Lowering the Eop of photoresist allows for reducing exposure time while maintaining the same exposure energy per unit area, thereby increasing production capacity. Furthermore, it allows for reducing the exposure energy per unit area per unit time while keeping the exposure time constant, thus reducing energy consumption. Therefore, lowering the optimal exposure energy of photoresist is crucial for increasing production capacity and reducing energy consumption.

[0004] Although positive photoresists have the advantage of higher resolution compared to negative photoresists, for currently known positive photoresists, reducing their optimal exposure energy inevitably sacrifices their resolution. This makes it difficult for currently known positive photoresists to achieve both lower exposure energy and higher resolution. Summary of the Invention

[0005] In view of this, the present invention provides a photoresist composition and a photolithography process, which can solve the above-mentioned technical problems.

[0006] Specifically, the following technical solutions are included:

[0007] On one hand, a photoresist composition is provided, the photoresist composition comprising: high molecular weight phenolic resin, low molecular weight phenolic resin, diazonaphthoquinone photosensitizer, phenolic hydroxyl compound and solvent;

[0008] Wherein, the high molecular weight phenolic resin has a molecular weight greater than or equal to 10,000, and the low molecular weight phenolic resin has a molecular weight less than or equal to 4,000.

[0009] The mass ratio of the high molecular weight phenolic resin to the low molecular weight phenolic resin is 0.1 to 9:1.

[0010] In some possible implementations, the molecular weight of the high molecular weight phenolic resin is 10,000 to 15,000; and / or,

[0011] The molecular weight of the low molecular weight phenolic resin is 2000-4000.

[0012] In some possible implementations, the high molecular weight phenolic resin and the low molecular weight phenolic resin constitute 5% to 15% by mass of the photoresist composition; and / or,

[0013] The phenolic hydroxyl compound is present in the photoresist composition at a mass percentage of 0.5% to 1%; and / or,

[0014] The mass ratio of the diazonaphthoquinone photosensitizer to the total mass of the high molecular weight phenolic resin and the low molecular weight phenolic resin is 1:2 to 5.

[0015] In some possible implementations, in both the high molecular weight phenolic resin and the low molecular weight phenolic resin, the molar ratio of p-cresol participating in the phenolic resin condensation in the phenolic raw materials is greater than 40%, the molar ratio of m-cresol participating in the phenolic resin condensation in the phenolic raw materials is greater than 40%, the molar ratio of 2,5-xylenol participating in the phenolic resin condensation in the phenolic resin condensation in the phenolic raw materials is greater than 3%, and the molar ratio of 3,5-xylenol participating in the phenolic resin condensation in the phenolic raw materials is greater than 3%.

[0016] In some possible implementations, the photoresist composition further includes at least one silane coupling agent and a leveling agent; and / or,

[0017] The silane coupling agent comprises 0.1% to 0.8% by mass in the photoresist composition; and / or,

[0018] The leveling agent is present in the photoresist composition at a mass percentage of 0.01% to 0.1%.

[0019] In some possible implementations, the diazononaphthoquinone photosensitizer is an esterification of diazononaphthoquinone sulfonyl chloride and a phenolic derivative.

[0020] In some possible implementations, the diazonaquinone sulfonyl chloride comprises: diazonaquinone-5-sulfonyl chloride and / or diazonaquinone-4-sulfonyl chloride; and / or,

[0021] The phenolic derivatives include at least one of the following: polyhydroxybenzophenone compounds, bis[(poly)hydroxyphenyl]alkyl compounds, tri(hydroxyphenyl)methanes or their methyl substitutes, and bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl substitutes.

[0022] In some possible implementations, the phenolic hydroxy compound contains at least two benzene rings connected by saturated C-C bond segments, each benzene ring is connected to 0 to 3 hydroxyl groups, and at least one benzene ring is connected to a hydroxyl group.

[0023] In some possible implementations, the phenolic hydroxy compound includes at least one of 2,2-bis(4-hydroxyphenyl)propane, 1,1,1-tris(4-hydroxyphenyl)-2-(4-hydroxyphenyl)ethane, 1,2,3,4-tetra(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, and α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene.

[0024] On the other hand, a photolithography process is provided, wherein the photolithography process employs any of the above-described photoresist compositions.

[0025] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0026] The photoresist composition provided in this invention includes a high molecular weight phenolic resin, a low molecular weight phenolic resin, a diazonoquinone photosensitizer, a phenolic hydroxyl compound, a solvent, and optionally a silane coupling agent and a leveling agent. By using the diazonoquinone photosensitizer, the phenolic resin is protected from erosion by the developer under unexposed conditions, and the dissolution rate of the photoresist in the developer is accelerated under exposed conditions. By using the phenolic hydroxyl compound, in synergy with other components in the system, the dissolution rate of the photoresist in the developer after exposure can be accelerated, significantly increasing the sensitivity of the photoresist. Optionally, a silane coupling agent is used to increase the adhesion between the photoresist and the substrate, and a leveling agent is used to improve the leveling performance of the positive photoresist, resulting in a smoother and more even photoresist film.

[0027] Specifically, by combining high molecular weight phenolic resin with a molecular weight greater than or equal to 10,000 and low molecular weight phenolic resin with a molecular weight less than or equal to 4,000, and working together with other components of the system, the high molecular weight phenolic resin is beneficial for improving the film retention rate of the positive photoresist, while the low molecular weight phenolic resin is beneficial for improving the sensitivity of the positive photoresist. By maintaining a mass ratio of high molecular weight phenolic resin to low molecular weight phenolic resin of 0.1 to 9:1, it is possible to ensure that the positive photoresist possesses both good sensitivity and film retention rate. In other words, the positive photoresist provided in the embodiments of the present invention, through the reasonable ratio of the above components, can simultaneously achieve improved low exposure energy, high resolution, high film retention rate, and excellent substrate adhesion and film thickness uniformity. Detailed Implementation

[0028] To make the technical solutions and advantages of this application clearer, the embodiments of this application will be described in further detail below.

[0029] Photoresist is a photosensitive hybrid photosensitive material, typically used in photolithography to fabricate fine patterns. In photolithography, the photoresist is coated onto a substrate. After exposure to light or radiation, the solubility of the photoresist in the developer changes, resulting in soluble and insoluble portions. For positive photoresist, after development, the soluble portions are washed away, and the insoluble portions form the photoresist layer with the desired pattern.

[0030] Specifically, in the array fabrication of TFT-LCD (Thin Film Transistor Liquid Crystal Display) display panels, positive photoresist is required to transfer the pattern from the photomask to the target substrate. For positive photoresist, the unexposed areas are difficult to dissolve in the developer, while the exposed areas are easily soluble. However, in current known TFT-LCD array processes, the improvement in yield (resolution, film retention, etc.) for positive photoresist is nearing saturation. Furthermore, due to the high cost and energy consumption of exposure equipment, the bottleneck for increasing throughput in TFT-LCD array processes lies in exposure speed, while the bottleneck for reducing energy consumption lies in exposure energy. Therefore, it is desirable to reduce the time and energy required for the exposure process of positive photoresist.

[0031] The optimal exposure energy (Eop) of photoresist refers to the exposure energy required to reproduce a pattern at a 1:1 scale. Lowering the Eop allows for reducing exposure time while maintaining the same exposure energy per unit area, thus increasing production capacity. It also allows for reducing the exposure energy per unit area per unit time while maintaining the same exposure time, thereby reducing energy consumption. The lower the Eop, the faster the photoresist becomes sensitive. Therefore, lowering the Eop is crucial for increasing production capacity and reducing energy consumption.

[0032] Although positive photoresists have the advantage of higher resolution compared to negative photoresists, for currently known positive photoresists, reducing their optimal exposure energy inevitably sacrifices their resolution and film retention rate. This makes it difficult for currently known positive photoresists to achieve both improved low exposure energy and high resolution and film retention rate.

[0033] To address the aforementioned technical problems, embodiments of the present invention provide a photoresist composition comprising: a high molecular weight phenolic resin, a low molecular weight phenolic resin, a diazonaphthoquinone photosensitizer, a phenolic hydroxyl compound, a solvent, and optionally a silane coupling agent and a leveling agent.

[0034] Among them, the molecular weight of high molecular weight phenolic resin is greater than or equal to 10,000, and the molecular weight of low molecular weight phenolic resin is less than or equal to 4,000; the mass ratio of high molecular weight phenolic resin to low molecular weight phenolic resin is 0.1 to 9:1.

[0035] The photoresist composition provided in this embodiment of the invention includes a high molecular weight phenolic resin, a low molecular weight phenolic resin, a diazonaphthoquinone photosensitizer, a phenolic hydroxyl compound, a solvent, and optionally a silane coupling agent and a leveling agent. Specifically, by combining a high molecular weight phenolic resin with a molecular weight greater than or equal to 10,000 and a low molecular weight phenolic resin with a molecular weight less than or equal to 4,000, and through their interaction with the diazonaphthoquinone photosensitizer and the phenolic hydroxyl compound, the high molecular weight phenolic resin is beneficial for improving the photoresist's film retention rate, while the low molecular weight phenolic resin is beneficial for improving the photoresist's sensitivity. By maintaining a mass ratio of high molecular weight phenolic resin to low molecular weight phenolic resin of 0.1 to 9:1, it is possible to ensure that the photoresist possesses both improved sensitivity and high film retention rate. In other words, the photoresist layer formed after curing by the photoresist composition provided in this embodiment of the invention can simultaneously possess improved low exposure energy and high resolution, excellent film thickness uniformity, and substrate adhesion.

[0036] Furthermore, in the photoresist composition provided in this embodiment of the invention, a diazonoquinone-based photosensitizer is used to protect the phenolic resin from being eroded by the developer under unexposed conditions and to accelerate the dissolution rate of the photoresist in the developer under exposed conditions. Furthermore, in this photoresist composition system, the use of a phenolic hydroxyl compound can accelerate the dissolution rate of the photoresist in the developer after exposure, significantly increasing the sensitivity of the photoresist. Furthermore, in this photoresist composition system, a silane coupling agent is used to increase the adhesion between the photoresist and the substrate, and a leveling agent is used to improve the leveling performance of the photoresist, resulting in a smoother and more even photoresist film. It is evident that, based on the synergistic effect of the above components in the photoresist, the photoresist possesses improved low exposure energy, high resolution, high film retention rate, and excellent overall performance (good film thickness uniformity and substrate adhesion).

[0037] The following is a further description of each component involved in the photoresist and its role in the photoresist system involved in the embodiments of the present invention:

[0038] For this high molecular weight phenolic resin, which is a linear phenolic resin, making its molecular weight greater than or equal to 10,000, for example, a molecular weight of 10,000 to 15,000, is very advantageous for ensuring a high film retention rate of the photoresist.

[0039] For this low molecular weight phenolic resin, which is a linear phenolic resin, making its molecular weight less than or equal to 4000, for example, a molecular weight of 2000 to 4000, is very advantageous for ensuring the high sensitivity of the photoresist.

[0040] By combining the aforementioned high-molecular-weight phenolic resin and low-molecular-weight phenolic resin, and working in conjunction with diazonoquinone-based photosensitizers, the photoresist exhibits two different development speeds in the exposed and unexposed areas, thereby achieving effective control over sensitivity and film retention.

[0041] Furthermore, the mass ratio of high molecular weight phenolic resin to low molecular weight phenolic resin is set to 0.1–9:1, for example, 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, etc. Studies have found that when the mass ratio is greater than 9:1, it is detrimental to improving the sensitivity of the positive photoresist; when the mass ratio is less than 0.1:1, it is detrimental to improving the film retention rate of the positive photoresist.

[0042] In some examples, using a mass ratio of high molecular weight phenolic resin to low molecular weight phenolic resin of 0.5 to 1.5:1 enables the photoresist to have both improved sensitivity and film retention.

[0043] It is known that phenolic resins, both high and low molecular weight, are prepared by polycondensation of aldehydes and phenolic raw materials. The molecular weight of phenolic resins is controlled by adjusting the molar ratio of aldehydes to phenolic raw materials to obtain phenolic resins within a specific molecular weight range.

[0044] Phenolic raw materials include, but are not limited to: p-cresol, m-cresol, 2,5-xylenol, and 3,5-xylenol. For both types of phenolic resins, the molar ratio of phenolic raw materials participating in the polycondensation reaction satisfies the following relationship:

[0045] (1) The molar percentage of p-cresol participating in the condensation of phenolic resin in phenolic raw materials is greater than or equal to 40%, which is beneficial to ensuring the high resolution and high film retention of positive photoresist.

[0046] (2) The molar percentage of m-cresol participating in the condensation of phenolic resin in phenolic raw materials is greater than or equal to 40%, which is beneficial to improving the sensitivity of positive photoresist.

[0047] (3) The molar percentage of 2,5-xylenol participating in the condensation polymerization of phenolic resin in the phenolic raw materials is greater than or equal to 3%, and the molar percentage of 3,5-xylenol participating in the condensation polymerization of phenolic resin in the phenolic raw materials is greater than or equal to 3%. This is beneficial for improving the film retention rate and resolution of the photoresist.

[0048] By controlling the ratio of aldehydes and the aforementioned phenolic raw materials, the molecular weight of the phenolic resin formed by the polycondensation reaction can be controlled, thereby obtaining high molecular weight phenolic resins and low molecular weight phenolic resins that meet the aforementioned molecular weight requirements.

[0049] Furthermore, in this embodiment of the invention, the softening points of both the high molecular weight phenolic resin and the low molecular weight phenolic resin are greater than 150°C to ensure that the photoresist layer has a high heat resistance temperature (heat resistance stability). This is because the post-baking stage after development generally requires a high temperature of above 120°C. By setting the softening point as described above, the rigidity of the photoresist layer can be increased to prevent the photoresist from softening and collapsing during the post-baking process, thereby preventing a decrease in resolution.

[0050] In some examples, the diazonoquinone photosensitizer is an ester of diazonoquinone sulfonyl chloride and a phenolic derivative. Under unexposed conditions, the photosensitizer undergoes an azo coupling reaction with the phenolic resin, which can resist the erosion of the developer. Under exposed conditions, it generates indole carboxylic acid, which helps to accelerate the dissolution rate of the photoresist in the developer.

[0051] For example, diazonaquinone sulfonyl chloride includes, but is not limited to: diazonaquinone-5-sulfonyl chloride and / or diazonaquinone-4-sulfonyl chloride, wherein diazonaquinone-5-sulfonyl chloride is also known as 2-diazo-1-naphthoquinone-5-sulfonyl chloride, with CAS number 3770-97-6; and diazonaquinone-4-sulfonyl chloride is also known as 1,2-naphthoquinone-2-diazido-4-sulfonyl chloride, with CAS number 36451-09-9.

[0052] For example, phenolic derivatives include, but are not limited to, polyhydroxybenzophenone compounds, bis[(poly)hydroxyphenyl]alkyl compounds, tri(hydroxyphenyl)methanes or their methyl substitutes.

[0053] For example, polyhydroxybenzophenone compounds include, but are not limited to: 2,3,4-trihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,3,6-trihydroxybenzophenone, 2,3,4-trihydroxy-2'-methylbenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3',4,4',6-pentahydroxybenzophenone, 2,2',3,4,4'-pentahydroxybenzophenone, 2,2',3,4,5-pentahydroxybenzophenone, 2,3',4,4',5',6-hexahydroxybenzophenone, and 2,3,3',4,4',5'-hexahydroxybenzophenone.

[0054] The bis[(poly)hydroxyphenyl]alkyl compounds include, but are not limited to: bis(2-hydroxyphenyl)methane (CAS No. 2467-02-9), bis(2,3,4-trihydroxyphenyl)methane, 2-(4-hydroxyphenyl)-2-(4'-hydroxyphenyl)propane, 2-(2,4-dihydroxyphenyl)-2-(2',4'-dihydroxyphenyl)propane, 2-(2,3,4-trihydroxyphenyl)-2-(2',3',4'-trihydroxyphenyl)propane, 4,4'-{1-[4-[2-(4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol, and 3,3'-dimethyl-{1-[4-[2-(3-methyl-4-hydroxyphenyl)-2-propyl]phenyl]ethylidene}bisphenol.

[0055] The tri(hydroxyphenyl)methanes or their methyl substitutes include, but are not limited to: tri(4-hydroxyphenyl)methane, bis(4-hydroxy-3,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-4-hydroxyphenylmethane, bis(4-hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, and bis(4-hydroxy-3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane.

[0056] The bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl substitutes include, but are not limited to: bis(3-cyclohexyl-4-hydroxyphenyl)-3-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-2-hydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxyphenyl)-4-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-2-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-hydroxyphenylmethane, bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)-4-hydroxyphenylmethane, bis(3-cyclohexyl-2-hydroxy ... Bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-4-hydroxyphenylmethane, Bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-3-hydroxyphenylmethane, Bis(5-cyclohexyl-4-hydroxy-3-methylphenyl)-2-hydroxyphenylmethane, Bis(3-cyclohexyl-2-hydroxyphenyl)-4-hydroxyphenylmethane, Bis(3-cyclohexyl-2-hydroxyphenyl)-2-hydroxyphenylmethane, Bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-2-hydroxyphenylmethane, Bis(5-cyclohexyl-2-hydroxy-4-methylphenyl)-4-hydroxyphenylmethane.

[0057] Exemplary examples include, but are not limited to, 2,3,4-trihydroxybenzophenone-diazonaphthoquinone sulfonyl chloride (i.e., an esterification of 2,3,4-trihydroxybenzophenone and diazonaphthoquinone sulfonyl chloride), 2,3,4,4'-tetrahydroxybenzophenone-diazonaphthoquinone sulfonyl chloride, bis(2,4-dihydroxyphenyl)methane-diazonaphthoquinone sulfonyl chloride, tris(4-hydroxyphenyl)methane-diazonaphthoquinone sulfonyl chloride, bis(3-cyclohexyl-4-hydroxyphenyl)-3-hydroxyphenylmethane-diazonaphthoquinone sulfonyl chloride, and bis(2-hydroxyphenyl)methane-diazonaphthoquinone sulfonic acid chloride. The aforementioned diazonaphthoquinone sulfonyl chloride can be either diazonaphthoquinone-5-sulfonyl chloride or diazonaphthoquinone-4-sulfonyl chloride.

[0058] In some examples, the mass ratio of the diazonaphthoquinone photosensitive agent to the two phenolic resins is 1:(2-5), which ensures that the photoresist has both high film retention and high sensitivity.

[0059] Phenolic compounds, when used in the photoresist compositions provided in the embodiments of the present invention, can accelerate the dissolution rate of the photoresist in the developer after exposure and increase the sensitivity of the photoresist. The phenolic compounds involved in the embodiments of the present invention refer to compounds containing at least two benzene rings connected by saturated carbon chains, with each benzene ring connected to 0 to 3 hydroxyl groups, and at least one benzene ring having a hydroxyl group attached.

[0060] Furthermore, the phenolic hydroxyl compound is selected from compounds containing at least two benzene rings connected by saturated carbon chains, with each benzene ring having 0 to 3 hydroxyl groups, and at least two benzene rings having hydroxyl groups attached.

[0061] For example, the phenolic hydroxy compound may contain 2 benzene rings, 3 benzene rings, 4 benzene rings, or 5 benzene rings.

[0062] For example, in this phenolic compound, each benzene ring may be without a hydroxyl group, or may be connected to one, two, or three hydroxyl groups.

[0063] For example, the phenolic compound may have hydroxyl groups attached to one, two, three, or four benzene rings.

[0064] In some examples, the phenolic hydroxy compound includes, but is not limited to, at least one of: 2,2-bis(4-hydroxyphenyl)propane, 1,1,1-tris(4-hydroxyphenyl)-2-(4-hydroxyphenyl)ethane, 1,2,3,4-tetra(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3-methylphenyl)propane (CAS No. 79-97-0), 2,2-bis(4-hydroxyphenyl)butane (CAS No. 77-40-7), and α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene (CAS No. 110726-28-8).

[0065] The chemical structural formula of 2,2-bis(4-hydroxyphenyl)propane is shown below:

[0066]

[0067] The chemical structural formula of 1,1,1-tris(4-hydroxyphenyl)-2-(4-hydroxyphenyl)ethane is shown below:

[0068]

[0069] The chemical structural formula of 1,2,3,4-tetra(4-hydroxyphenyl)butane is shown below:

[0070]

[0071] In this embodiment of the invention, a leveling agent is used to reduce the surface tension of the positive photoresist, thereby improving the leveling performance of the photoresist. The leveling agent is a fluorinated surfactant, and when it is selected from perfluoroalkanes with 2-6 carbon atoms, it has the purpose of optimizing the above-mentioned effect.

[0072] In some examples, the perfluoroalkanes with 2-6 carbon atoms mentioned above include at least one of perfluoropropane, perfluorobutane, perfluoroethane, perfluoroisobutane, and perfluoropentane.

[0073] The photoresist provided in this embodiment of the invention uses a solvent to disperse phenolic resin and other components, resulting in a uniform photoresist composition, which facilitates uniform coating of the photoresist onto the substrate.

[0074] By way of example, solvents suitable for use in embodiments of the present invention include, but are not limited to, at least one of ethylene glycol alkyl ethers, diethylene glycol dialkyl ethers, propylene glycol alkyl ether acetates, and ketones.

[0075] For example, ethylene glycol alkyl ethers include, but are not limited to: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, etc.; diethylene glycol dialkyl ethers include, but are not limited to: diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, etc.; propylene glycol alkyl ether acetates include, but are not limited to: propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, etc.; ketones include, but are not limited to: acetone, methyl ethyl ketone, cyclohexanone, methyl amyl ketone, etc.

[0076] In some examples, silane coupling agents suitable for embodiments of the present invention include, but are not limited to, the following: γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, etc.

[0077] The mass ratio of each component in the photoresist also plays a positive role in optimizing its sensitivity and film formation rate. In some examples, the mass percentage of high molecular weight phenolic resin and low molecular weight phenolic resin in the photoresist composition is 5% to 15% by mass; the mass percentage of phenolic hydroxyl compound in the photoresist composition is 0.5% to 1% by mass; the mass ratio of diazonaphthoquinone photosensitizer to the total mass of high molecular weight phenolic resin and low molecular weight phenolic resin is 1:2 to 5; and the solvent is the balance, for example, the mass percentage of solvent is 80% to 90%.

[0078] For example, the photoresist comprises the following components in weight percentages: 5%–15% high molecular weight phenolic resin and low molecular weight phenolic resin, 1.5%–12% diazonoquinone photosensitizer, 0.5%–1% phenolic hydroxyl compound, 0.1%–0.8% silane coupling agent, 0.01%–0.1% leveling agent, and 80%–90% solvent. Further, the leveling agent has a weight percentage of 0.03%–0.07%.

[0079] In summary, the photoresist provided in this embodiment of the invention, based on the synergistic effect of its various components, requires only a lower optimal exposure energy when used in photolithography processes to prepare photolithographic patterns, while still maintaining high resolution, high film retention, good film thickness uniformity, and substrate adhesion. Furthermore, this photoresist also possesses excellent other photolithographic properties, such as contrast ratio and acid / alkali resistance. This makes this positive photoresist particularly suitable for the array processing of TFT-LCD (Thin Film Transistor-Liquid Crystal Display) display panels, effectively increasing production capacity and reducing power consumption.

[0080] On the other hand, embodiments of the present invention also provide a method for preparing a photoresist, wherein the photoresist is prepared using a photoresist composition as shown in any of the above descriptions, and the method for preparing the photoresist includes:

[0081] High molecular weight phenolic resin and low molecular weight phenolic resin are stirred evenly in a solvent. Then, a diazonoquinone photosensitizer, a phenolic hydroxyl compound, and optionally a silane coupling agent and a leveling agent are added and stirred until homogeneous to obtain the photoresist. To ensure thorough and uniform dissolution of all components, each component can be added to the solvent sequentially for dissolution.

[0082] In another aspect, embodiments of the present invention also provide a photolithography process, which employs any of the above-mentioned photoresist compositions.

[0083] For example, the operation steps involved in this photolithography process are as follows:

[0084] A photoresist is prepared using a photoresist composition. The photoresist is then uniformly coated onto the surface of a substrate (e.g., a 4-inch silicon wafer) at a spin coater at a speed of 500-600 rpm. The photoresist coating is dried by baking at 100-140°C for 70-120 seconds. The coating is then exposed to light through a photomask. After exposure, the photoresist coating is developed using a developer. The exposed portion of the photoresist coating dissolves in the developer, while the unexposed portion remains undissolved, thus obtaining the desired photolithographic pattern.

[0085] Preferred embodiments of the present invention will now be described in more detail. While preferred embodiments of the present invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with techniques or conditions described in the literature in the art or according to product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0086] The 2,3,4,4'-tetrahydroxybenzophenone-diazonaphthoquinone-5-sulfonate chloride ester mentioned in the following examples refers to the esterification of 2,3,4,4'-tetrahydroxybenzophenone and diazonaphthoquinone-5-sulfonate chloride;

[0087] 2,3,4,4'-Tetrahydroxybenzophenone-diazonaphthoquinone-4-sulfonate chloride refers to the esterification of 2,3,4,4'-tetrahydroxybenzophenone and diazonaphthoquinone-4-sulfonate chloride;

[0088] 2,3,4-Trihydroxybenzophenone-diazonaphthoquinone-4-sulfonate chloride refers to the esterification of 2,3,4-trihydroxybenzophenone and diazonaphthoquinone-4-sulfonate chloride.

[0089] Bis(2-hydroxyphenyl)methane-diazonaphthoquinone-4-sulfonate chloride refers to the esterification of bis(2-hydroxyphenyl)methane and diazonaphthoquinone-4-sulfonate chloride;

[0090] Bis(2-hydroxyphenyl)methane-diazonaphthoquinone-5-sulfonate chloride refers to the esterification of bis(2-hydroxyphenyl)methane and diazonaphthoquinone-5-sulfonate chloride.

[0091] Example 1

[0092] Example 1 provides a photoresist comprising the following components in weight percentages: 4.8% high molecular weight phenolic resin, 7.2% low molecular weight phenolic resin, 3% chloro 2,3,4,4'-tetrahydroxybenzophenone-diazonaphthoquinone-5-sulfonate, 0.6% 2,2-bis(4-hydroxyphenyl)propane, 0.3% γ-aminopropyltriethoxysilane, 0.1% perfluoroethane, and 84% propylene glycol methyl ether acetate.

[0093] The high molecular weight phenolic resin has a molecular weight of 12318, and the low molecular weight phenolic resin has a molecular weight of 3289. Among the phenolic raw materials participating in the condensation of phenolic resin, the molar percentage of p-cresol is 50%, the molar percentage of m-cresol is 40%, the molar percentage of 2,5-xylenol is 5%, and the molar percentage of 3,5-xylenol is equal to 5%.

[0094] Example 2

[0095] Example 2 provides a photoresist comprising the following components in weight percentages: 7.5% high molecular weight phenolic resin, 7.5% low molecular weight phenolic resin, 5% chloro 2,3,4,4'-tetrahydroxybenzophenone-diazonaphthoquinone-4-sulfonate, 0.8% 2,2-bis(4-hydroxy-3-methylphenyl)propane, 0.5% γ-methacryloyloxypropyltrimethoxysilane, 0.05% perfluoroisobutane, and 78.65% propylene glycol methyl ether acetate.

[0096] The high molecular weight phenolic resin has a molecular weight of 14,500, and the low molecular weight phenolic resin has a molecular weight of 3,000. Among the phenolic raw materials participating in the condensation of phenolic resin, the molar percentage of p-cresol is 50%, the molar percentage of m-cresol is 40%, the molar percentage of 2,5-xylenol is 5%, and the molar percentage of 3,5-xylenol is equal to 5%.

[0097] Example 3

[0098] Example 3 provides a photoresist comprising the following components in weight percentages: 7.2% high molecular weight phenolic resin, 4.8% low molecular weight phenolic resin, 4% chloro 2,3,4-trihydroxybenzophenone-diazonaphthoquinone-4-sulfonate, 1% 1,2,3,4-tetra(4-hydroxyphenyl)butane, 0.8% γ-methacryloyloxypropyltrimethoxysilane, 0.1% perfluoroisobutane, and 82.1% propylene glycol methyl ether acetate.

[0099] The high molecular weight phenolic resin has a molecular weight of 11,000, and the low molecular weight phenolic resin has a molecular weight of 2,500. Among the phenolic raw materials participating in the condensation of phenolic resin, the molar percentage of p-cresol is 50%, the molar percentage of m-cresol is 40%, the molar percentage of 2,5-xylenol is 5%, and the molar percentage of 3,5-xylenol is equal to 5%.

[0100] Example 4

[0101] Example 4 provides a photoresist comprising the following components in weight percentages: 4% high molecular weight phenolic resin, 6% low molecular weight phenolic resin, 3.5% bis(2-hydroxyphenyl)methane-diazonaphthoquinone-4-sulfonate, 0.9% 1,1,1-tris(4-hydroxyphenyl)-2-(4-hydroxyphenyl)ethane, 0.5% γ-aminopropyltriethoxysilane, 0.1% perfluoroethane, and 85% propylene glycol methyl ether acetate.

[0102] The high molecular weight phenolic resin has a molecular weight of 10,500, and the low molecular weight phenolic resin has a molecular weight of 3,500. Among the phenolic raw materials participating in the condensation of phenolic resin, the molar percentage of p-cresol is 50%, the molar percentage of m-cresol is 40%, the molar percentage of 2,5-xylenol is 5%, and the molar percentage of 3,5-xylenol is equal to 5%.

[0103] Example 5

[0104] Example 5 provides a photoresist comprising the following components in weight percentages: 6% high molecular weight phenolic resin, 4% low molecular weight phenolic resin, 3% bis(2-hydroxyphenyl)methane-diazonaphthoquinone-5-sulfonate, 0.5% 2,2-bis(4-hydroxyphenyl)butane, 0.4% 3-mercaptopropyltriethoxysilane, 0.08% perfluoropentane, and 86.02% propylene glycol methyl ether acetate.

[0105] The high molecular weight phenolic resin has a molecular weight of 13,500, and the low molecular weight phenolic resin has a molecular weight of 4,000. Among the phenolic raw materials participating in the condensation of phenolic resin, the molar percentage of p-cresol is 50%, the molar percentage of m-cresol is 40%, the molar percentage of 2,5-xylenol is 5%, and the molar percentage of 3,5-xylenol is equal to 5%.

[0106] Test case

[0107] Photolithographic patterns were prepared using the positive photoresist provided in Examples 1-5, and the specific photolithography process is shown below:

[0108] The high molecular weight phenolic resin and low molecular weight phenolic resin in the above proportions are added sequentially to propylene glycol methyl ether acetate and stirred evenly. Then, diazonoquinone photosensitizer, phenolic hydroxy compound, silane coupling agent and leveling agent are added sequentially and stirred evenly to obtain the photoresist composition of the present invention.

[0109] The prepared photoresist composition was uniformly coated onto the surface of a 4-inch silicon wafer at a speed of 550 rpm using a spin coating machine. The wafer was then heated with a hot plate at 120°C for 100 seconds to form a photoresist baking layer.

[0110] The initial thickness of the photoresist baking layer on the silicon wafer surface was measured using an optical thickness gauge and denoted as t1. Subsequently, the photoresist baking layer was exposed using a GHI-line mixed-line light source with a mask plotted with a 4.0 μm L&S resist pattern. After exposure, the photoresist pattern was obtained by developing with 2.38% tetramethylammonium hydroxide (TMAH) at 23°C for 60 s, washing with water for 30 s, and drying. The thickness of the photoresist pattern in the unexposed area was measured using an optical thickness gauge and denoted as t2.

[0111] The performance evaluation method for positive photoresist is as follows:

[0112] (1) Sensitivity

[0113] During photoresist exposure, the exposure machine energy is measured using an illuminometer (i.e., a UV energy meter), and the total exposure energy received by the photoresist is adjusted by the exposure time. After development, the width of the photoresist lines corresponding to the 4.0 μm L&S resist pattern is measured using a laser microscope and recorded.

[0114] Repeat the above steps and conduct experiments with the total exposure energy as the gradient to obtain the total exposure energy corresponding to a photoresist line width of approximately 4µm. This energy is the Eop of the photoresist.

[0115] (2) Film retention rate

[0116] Retention rate = (t2 / t1)*100%. The higher the retention rate, the less the unexposed photoresist is lost during development, which is beneficial for obtaining a good photoresist pattern.

[0117] (3) Resolution

[0118] After determining the optimal exposure energy (Eop) for the photoresist, the positive photoresist in each embodiment was exposed using masks with L&S resist patterns of 1.0 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 μm, based on the exposure energy of the Eop value. After exposure and development, the photoresist lines corresponding to the 1.0 / 1.1 / 1.2 / 1.3 / 1.4 / 1.5 / 1.6 / 1.7 / 1.8 / 1.9 μm L&S resist patterns were observed.

[0119] If the photoresist lines are complete, with smooth edges, no adhesion or defects, and the linewidth matches the mask linewidth, then the photoresist resolution is considered to meet the corresponding width. The smaller the corresponding linewidth that the photoresist can achieve, the higher its resolution.

[0120] (4) Adhesion

[0121] After baking, the adhesion of the photoresist baked layer is measured using the cross-cut adhesion test method according to ISOR1514 and ISO2808 standards. If no photoresist squares are peeled off in the 1mm squares, the adhesion is considered excellent; if no photoresist squares are peeled off in the 2mm squares, the adhesion is considered average; if no photoresist squares are peeled off in the 3mm squares, the adhesion is considered poor.

[0122] (5)Film thickness uniformity

[0123] The photoresist provided in each embodiment was applied to a 4-inch silicon wafer using a slit coating method, and at least 32 points were uniformly sampled in a circular array. The film thickness was measured at these sampling points using an optical film thickness gauge.

[0124] Among them, film thickness uniformity (U%) = (maximum film thickness - minimum film thickness) / (maximum film thickness + minimum film thickness) * 100%, and U% is required to be <1.

[0125] The relevant performance test results of the positive photoresists in Examples 1-5 are shown in Tables 1-6 respectively:

[0126] Table 1

[0127]

[0128] As shown in Table 1, the positive photoresists provided in Examples 1-5 all exhibited high sensitivity characteristics (EOP: below 26mj). Among them, the sensitivity of Example 1 was between 24mj and 26mj, the sensitivity of Examples 2, 4, and 5 was between 22mj and 24mj, and Example 3 had the best sensitivity at 22mj.

[0129] Table 2

[0130]

[0131] As shown in Table 2, the positive photoresists provided in Examples 1-5 all exhibited high film retention rates, with a film retention rate of over 99%.

[0132] Table 3

[0133]

[0134] As shown in Table 3, the photoresists provided in Examples 1-5 all exhibit excellent resolution (the photoresist can achieve a corresponding linewidth of less than 1.2 μm), adhesion (no peeling of 1 mm squares, and smooth and flat edges of the squares), and film thickness uniformity (U% less than 0.5%).

[0135] The above description is merely for the purpose of enabling those skilled in the art to understand the technical solutions of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photoresist composition, characterized in that, The photoresist composition comprises: high molecular weight phenolic resin, low molecular weight phenolic resin, diazonaphthoquinone photosensitizer, phenolic hydroxyl compound, and solvent; Wherein, the high molecular weight phenolic resin has a molecular weight greater than or equal to 10,000, and the low molecular weight phenolic resin has a molecular weight less than or equal to 4,000. The mass ratio of the high molecular weight phenolic resin to the low molecular weight phenolic resin is 0.1~9:1; The high molecular weight phenolic resin and the low molecular weight phenolic resin constitute 5% to 15% of the photoresist composition by weight (100% by weight); and / or, The phenolic hydroxyl compound is present in the photoresist composition at a mass percentage of 0.5% to 1%; and / or, The mass ratio of the diazonaphthoquinone photosensitizer to the total mass of the high molecular weight phenolic resin and the low molecular weight phenolic resin is 1:2~5; The diazononaphthoquinone photosensitizer is an esterification of diazononaphthoquinone sulfonyl chloride and a phenolic derivative; The phenolic hydroxy compounds include at least one of 2,2-bis(4-hydroxyphenyl)propane, 1,1,1-tris(4-hydroxyphenyl)-2-(4-hydroxyphenyl)ethane, 1,2,3,4-tetra(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, and α,α,α'-tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene.

2. The photoresist composition according to claim 1, characterized in that, The high molecular weight phenolic resin has a molecular weight of 10,000 to 15,000; and / or, The molecular weight of the low molecular weight phenolic resin is 2000~4000.

3. The photoresist composition according to claim 1, characterized in that, In both the high-molecular-weight phenolic resin and the low-molecular-weight phenolic resin, the molar ratio of p-cresol participating in the phenolic resin condensation in the phenolic raw materials is greater than 40%, the molar ratio of m-cresol participating in the phenolic resin condensation in the phenolic raw materials is greater than 40%, the molar ratio of 2,5-xylenol participating in the phenolic resin condensation in the phenolic resin condensation in the phenolic raw materials is greater than 3%, and the molar ratio of 3,5-xylenol participating in the phenolic resin condensation in the phenolic raw materials is greater than 3%.

4. The photoresist composition according to any one of claims 1-3, characterized in that, The photoresist composition further includes at least one silane coupling agent and a leveling agent; and / or, The silane coupling agent is present in the photoresist composition at a mass percentage of 0.1% to 0.8%; and / or, The leveling agent is present in the photoresist composition at a mass percentage of 0.01% to 0.1%.

5. The photoresist composition according to claim 1, characterized in that, The diazonaquinone sulfonyl chloride comprises: diazonaquinone-5-sulfonyl chloride and / or diazonaquinone-4-sulfonyl chloride; and / or, The phenolic derivatives include at least one of the following: polyhydroxybenzophenone compounds, bis[(poly)hydroxyphenyl]alkyl compounds, tri(hydroxyphenyl)methanes or their methyl substitutes, bis(cyclohexylhydroxyphenyl)(hydroxyphenyl)methanes or their methyl substitutes.

6. A photolithography process, characterized in that, The photolithography process uses the photoresist composition according to any one of claims 1-5.

Images