A low-temperature curing chemically amplified positive photosensitive polyimide and preparation method thereof

Abstract

The invention discloses a low-temperature solidified chemically amplified positive photosensitive polyimide and a preparation method thereof, and relates to the field of photoresist technology. The raw material composition of the positive photosensitive polyimide is, by mass percentage, 10-40% of polyimide resin, 1-15% of photoacid generator, and 55-70% of organic solvent. The polyimide resin of the invention has high permeability and high i-line transmittance. The prepared positive photosensitive polyimide greatly reduces exposure energy, improves film retention rate, and has low production cost.

Description

Technical Field

[0001] The invention relates to the technical field of photoresists, and in particular to a low-temperature solidified chemically amplified positive photosensitive polyimide and a preparation method thereof. Background Art

[0002] Polyimide has excellent thermal, mechanical and electrical properties. It is the preferred material for stress buffer layer, passivation layer and interlayer dielectric layer in integrated circuits. In these applications, polyimide needs to be patterned to achieve interconnection of specific areas of the chip. The early patterning of polyimide was achieved with the help of photoresist, which had complicated processes and low yield. To solve this problem, photosensitive polyimide materials appeared. Its patterning mechanism is the same as that of photoresist. Photochemical reaction occurs in the exposed area, resulting in a difference in solubility between the exposed area and the non-exposed area in the developer.

[0003] Currently, the commercialized photosensitive polyimides mainly include ester-type negative photosensitive polyimide and positive photosensitive polyimide of polyimide precursor combined with diazonaphthoquinone system. They ultimately require high-temperature curing at 300-350°C, and the film retention rate is less than 70%. At the same time, due to the low transmittance of the resin in the i-line, a very high exposure is required when making thick films, resulting in low resolution and high process costs. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a low-temperature curing chemically amplified positive photosensitive polyimide is provided, which has low curing temperature, high film retention rate, high resolution and low cost.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A low-temperature curing chemically amplified positive photosensitive polyimide, wherein the raw material composition of the positive photosensitive polyimide is as follows by mass percentage:

[0007] Polyimide resin 10~40%

[0008] Photoacid generator 1~15%

[0009] Organic solvent 55-70%;

[0010] The method for preparing the low-temperature cured chemically amplified positive photosensitive polyimide comprises the following steps:

[0011] S1. Preparation of polyimide resin

[0012] Add diamine and polar solvent to the reaction kettle, stir and dissolve under nitrogen atmosphere, then add dianhydride, react at room temperature for 2-4h, then add xylene, mix well and heat to 170-190℃ and continue to react for 2-4h, then cool to room temperature and add di-tert-butyl dicarbonate, react at room temperature for 6-8h, cool the reaction solution and pour into deionized water to obtain white precipitate, wash the white precipitate 3-5 times, and vacuum dry at 50℃ for 40-50h to obtain high permeability polyimide resin;

[0013] S2. Preparation of positive photosensitive polyimide

[0014] The polyimide resin, photoacid generator and organic solvent are mixed evenly and filtered with a 0.45 μm filter membrane to obtain a positive photosensitive polyimide solution;

[0015] Spin coating the above-mentioned photosensitive polyimide solution with a thickness of 14 μm after soft-testing on a dry silicon wafer, use i-line exposure, and then bake on a hot plate at 110 to 130° C. for 80 to 100 seconds. The baked wafer is developed with 2.38% TMAH for 90 to 100 seconds and rinsed with deionized water to obtain a patterned polyimide.

[0016] The silicon wafer that has completed the photolithography process is placed in an oxygen-free oven and treated at 200° C. for 0.5 to 1.5 hours to completely cure the photosensitive polyimide to obtain a positive photosensitive polyimide.

[0017] Preferably, the polyimide resin is synthesized from dianhydride and diamine in a polar solvent, and the molecular weight of the polyimide resin is between 1,000 and 100,000.

[0018] Preferably, the dianhydride is one or two of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthenetetracarboxylic dianhydride, hexafluoro dianhydride, hydrogenated pyromellitic dianhydride, and cyclobutanetetracarboxylic dianhydride.

[0019] Preferably, the diamine is one or two of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)-(1,1'-diphenyl)-4,4'-diamine, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, and 2,2-bis(4-aminophenyl)hexafluoropropane.

[0020] Preferably, the photoacid generator is one or a combination of two or more of triazines, sulfonates, hexafluoroantimonates, thiocyanates, and iodonium salts.

[0021] Preferably, the organic solvent is one or a combination of two or more of N-methylpyrrolidone, γ-butyl ester, ethyl lactate, N,N-dimethylformamide, N,N-dimethylacetamide, cyclopentanone, tetrahydrofuran, ethylene glycol methyl ether, and diethylene glycol methyl ether.

[0022] Preferably, in step S1, the molar ratio of diamine, dianhydride, xylene and di-tert-butyl dicarbonate is 1:1-1.05:3.5-4:18-22.

[0023] Preferably, the softening temperature of the photosensitive polyimide solution in step S2 is 95-105°C / 3min, and the exposure dose of the i-line is 190-210mj / cm 2 .

[0024] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. The polyimide resin of the present invention has high transmittance, and the transmittance in i-line is high. The prepared positive photosensitive polyimide greatly reduces the exposure energy and improves the film retention rate.

[0026] 2. The low-temperature-cured chemically amplified positive photosensitive polyimide of the present invention is cured at a low temperature of 200° C. and has excellent thermal, mechanical and electrical properties after curing.

[0027] 3. The low-temperature curing chemically amplified positive photosensitive polyimide of the present invention has low production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the resolution image of the polyimide resin PI001 in Example 1 under a 2000x electron microscope;

[0029] Figure 2 This is the resolution image of the polyimide resin PI002 in Example 1 under a 6000x electron microscope;

[0030] Figure 3 This is the resolution image of the polyimide resin PI003 in Example 1 under a 6000x electron microscope. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the embodiments.

[0032] Example 1

[0033] Synthesis of highly permeable polyimide resin PI001

[0034] Add 0.1 mol of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane and 300g of N-methylpyrrolidone to a three-necked flask, stir and dissolve under nitrogen atmosphere, then add 0.1 mol of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride, react at room temperature for 3 hours, add 40g of xylene, mix well and heat to 180℃ for 3 hours. After cooling to room temperature, add 2 mol of di-tert-butyl dicarbonate and react at room temperature for 7 hours. After cooling the reaction solution, pour it into 5L of deionized water to obtain a white precipitate. After washing the white precipitate 3 to 5 times, dry it in a 50℃ vacuum drying oven for 48 hours to obtain a high permeability polyimide resin PI001.

[0035] Take 1.0g PI001 resin, 0.1g dimethyl benzyl trifluoromethanesulfonate, and 8.9g γ-butyl ester, mix them evenly, and filter them with a 0.45μm filter membrane to obtain a positive photosensitive polyimide solution. Spin coat the photosensitive polyimide solution with a thickness of 14μm on a dry silicon wafer after soft-coating. The soft-coating temperature is 100℃ / 3min, and the i-line exposure is 200mj / cm 2 , and then baked on a hot plate at 120°C for 90s. The baked wafer was developed with 2.38% TMAH for 90s and rinsed with deionized water to obtain a patterned polyimide. The silicon wafer that has completed the photolithography process was placed in an oxygen-free oven and treated at 200°C for 1h to completely cure the photosensitive polyimide to obtain a positive photosensitive polyimide.

[0036] Example 2

[0037] Synthesis of highly permeable polyimide resin PI002

[0038] Add 0.05mol of 2,2-bis(4-hydroxy-3-aminophenyl)propane, 0.05mol of 2,2'-bis(trifluoromethyl)-(1,1'-diphenyl)-4,4'-diamine, and 300g of N-methylpyrrolidone to a three-necked flask and stir to dissolve under a nitrogen atmosphere. Then add 0.05mol of hexafluorodianhydride and 0.055mol of hydrogenated pyromellitic dianhydride. After reacting at room temperature for 2h, add 37g of xylene, mix well, and heat to 170℃ for 2h. After cooling to room temperature, add 1.8mol of di-tert-butyl dicarbonate and react at room temperature for 6h. After cooling the reaction solution, pour it into 5L of deionized water to obtain a white precipitate. After washing the white precipitate 3 to 5 times, dry it in a 50℃ vacuum drying oven for 40h to obtain a high-permeability polyimide resin PI002.

[0039] Take 2.0g of the above PI002 resin, 0.5g of diphenyl-(4-phenylthio)phenylsulfonium hexafluoroantimonate, 0.5g of 2-(9-anthrylvinyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, 7g of a mixed solvent of ethyl lactate, N,N-dimethylformamide and N,N-dimethylacetamide (the mass ratio of ethyl lactate, N,N-dimethylformamide and N,N-dimethylacetamide is 1:2:1), mix them evenly and filter them with a 0.45μm filter membrane to obtain a positive photosensitive polyimide solution. Spin coat the above photosensitive polyimide solution with a thickness of 14μm after soft-coating on a dry silicon wafer by spin coating, the soft-coating temperature is 95℃ / 3min, and i-line exposure is 190mj / cm 2 , and then baked on a hot plate at 110℃ for 80s. The baked wafer was developed with 2.38% TMAH for 95s and rinsed with deionized water to obtain a patterned polyimide. The silicon wafer that has completed the photolithography process was placed in an oxygen-free oven and treated at 200℃ for 0.5h to completely cure the photosensitive polyimide to obtain a positive photosensitive polyimide.

[0040] Example 3

[0041] Synthesis of highly permeable polyimide resin PI003

[0042] Add 0.05mol of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 0.05mol of 2,2-bis(4-aminophenyl)hexafluoropropane and 300g of N-methylpyrrolidone to a three-necked flask, stir and dissolve under nitrogen atmosphere, then add 0.05mol of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride (6FCDA), 0.05mol of cyclobutane tetracarboxylic dianhydride, react at room temperature for 4h, then add 42.5g of xylene, mix well and heat to 190℃ for 4h. After cooling to room temperature, add 2.2mol of di-tert-butyl dicarbonate and react at room temperature for 8h. After cooling the reaction solution, pour it into 5L of deionized water to obtain a white precipitate. After washing the precipitate 3 to 5 times, dry it in a 50℃ vacuum drying oven for 50h to obtain a high permeability polyimide resin PI003.

[0043] Take 4.0g of the above PI003 resin, 0.75g of triarylsulfonium salt, 0.75g of diphenyl tetrafluoroborate iodonium salt, 4.5g of a mixed solvent of cyclopentanone, tetrahydrofuran and ethylene glycol methyl ether (the mass ratio of cyclopentanone, tetrahydrofuran and ethylene glycol methyl ether is 2:1:2), mix them evenly and filter them with a 0.45μm filter membrane to obtain a positive photosensitive polyimide solution. Spin-coat the above photosensitive polyimide solution with a thickness of 14μm after soft-coating on a dry silicon wafer, the soft-coating temperature is 105℃ / 3min, and i-line exposure is 210mj / cm 2, and then baked on a hot plate at 130℃ for 100s. The baked wafer was developed with 2.38% TMAH for 100s and rinsed with deionized water to obtain patterned polyimide. The silicon wafer that has completed the photolithography process was placed in an oxygen-free oven and treated at 200℃ for 1.5h to completely cure the photosensitive polyimide to obtain positive photosensitive polyimide.

[0044] The performance of the polyimide resins PI001-PI003 in Examples 1-3 was tested, and the results are shown in Table 1.

[0045] Table 1

[0046]

[0047] It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

Claims

1. A low temperature curing chemically amplified positive photosensitive polyimide, characterized in that: The raw material composition of the positive photosensitive polyimide is as follows by mass percentage: Polyimide resin 10~40% Photoacid generator 1~15% Organic solvent 55-70%; The method for preparing the low-temperature cured chemically amplified positive photosensitive polyimide comprises the following steps: S1. Preparation of polyimide resin Add diamine and polar solvent to a reaction kettle, stir and dissolve under nitrogen atmosphere, then add dianhydride, react at room temperature for 2-4 hours, then add xylene, mix well and heat to 170-190°C and continue to react for 2-4 hours, then cool to room temperature and add di-tert-butyl dicarbonate, react at room temperature for 6-8 hours, cool the reaction solution and pour into deionized water to obtain a white precipitate, wash the white precipitate 3-5 times, and vacuum dry at 50°C for 40-50 hours to obtain a highly permeable polyimide resin, wherein the molecular weight of the polyimide resin is between 1000 and 100000; S2. Preparation of positive photosensitive polyimide The polyimide resin, photoacid generator and organic solvent are mixed evenly and filtered with a 0.45 μm filter membrane to obtain a positive photosensitive polyimide solution; The photosensitive polyimide solution of 14 μm after soft-testing is coated on the dried silicon wafer by spin coating, and then exposed by i-line, and then baked on a hot plate at 110-130° C. for 80-100 seconds. The baked wafer is developed with 2.38% TMAH for 90-100 seconds, and rinsed with deionized water to obtain a patterned polyimide; The silicon wafer after the photolithography process is placed in an oxygen-free oven and treated at 200° C. for 0.5 to 1.5 hours to completely cure the photosensitive polyimide to obtain a positive photosensitive polyimide; The dianhydride is one or two of 9,9-bis(trifluoromethyl)-2,3,6,7-oxanthene tetracarboxylic dianhydride, hexafluoro dianhydride, hydrogenated pyromellitic dianhydride, and cyclobutanetetracarboxylic dianhydride; The diamine is one or two of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)-(1,1'-diphenyl)-4,4'-diamine, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, N,N'-(2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-diyl)bis(4-aminobenzamide), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene, 2,2-bis(4-hydroxy-3-aminophenyl)propane, and 2,2-bis(4-aminophenyl)hexafluoropropane.

2. A low temperature curing chemically amplified positive photosensitive polyimide as claimed in claim 1, characterized in that: The photoacid generator is one or a combination of two or more of triazines, sulfonates, hexafluoroantimonates, thiocyanates and iodonium salts.

3. The low temperature curing chemically amplified positive photosensitive polyimide according to claim 1, characterized in that: The organic solvent is one or a combination of two or more of N-methylpyrrolidone, γ-butyl ester, ethyl lactate, N,N-dimethylformamide, N,N-dimethylacetamide, cyclopentanone, tetrahydrofuran, ethylene glycol methyl ether, and diethylene glycol methyl ether.

4. The low temperature curing chemically amplified positive photosensitive polyimide according to claim 1, characterized in that: In step S1, the molar ratio of diamine, dianhydride, xylene and di-tert-butyl dicarbonate is 1:1-1.05:3.5-4:18-22.

5. The low temperature curing chemically amplified positive photosensitive polyimide according to claim 1, characterized in that: In step S2, the softening temperature of the photosensitive polyimide solution is 95-105°C / 3min, and the exposure dose of the i-line is 190-210mj / cm 2 .

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