Photosensitive polyimide, preparation method, polyimide film and circuit board

Abstract

The invention discloses photosensitive polyimide, a preparation method, a polyimide film and a circuit board. The photosensitive polyimide is prepared by polymerizing a dianhydride monomer and a diamine monomer containing a cyclobutane group and carrying out imidization. The photosensitive polyimide disclosed by the invention is suitable for a KrF light source with the wavelength of 248nm, has excellent adaptability to manufacturing of a micro-size structure, and can meet the manufacturing requirement of a fine structure; in addition, the photosensitive polyimide also has excellent etching resistance and high retention rate, and can maintain high stability and reliability in a complex semiconductor manufacturing process.

Description

Technical Field

[0001] The invention relates to the technical field of photoresists, and in particular to a photosensitive polyimide, a preparation method, a polyimide film and a circuit board. Background Art

[0002] Photosensitive polyimide (PSPI) is an important organic material with excellent performance and a wide range of applications. It has the functions of both photoresist and dielectric insulating layer, and can achieve polyimide (PI) film patterning without the help of other photoresists, thereby saving material costs and significantly shortening related manufacturing processes. With its unique performance and process advantages, PSPI is widely used in high-end fields such as OLED (Organic Light-Emitting Diode) and integrated circuits. The UV exposure wavelengths of common polyimide photoresists are mainly concentrated in the i-line (365nm) and g-line (436nm), and the shorter wavelength KrF (248nm) is rarely involved.

[0003] This patent application aims to introduce a photosensitive polyimide suitable for KrF photoresist. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a photosensitive polyimide suitable for KrF photoresist.

[0005] To achieve the above purpose, the technical method adopted by the present invention is as follows:

[0006] A photosensitive polyimide is prepared by polymerization of a dianhydride monomer and a diamine monomer containing a cyclobutane group and imidization, wherein the diamine monomer containing a cyclobutane group has a structure shown in Formula 1:

[0007]

[0008] Among them, R1 is selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms, or a divalent linking group that forms a part of a bond to Ar1 to form a ring; R4 is selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms, or a divalent linking group that forms a part of a bond to Ar2 to form a ring; R2, R3, R5 and R6 are independently selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms; Ar1 ​​and Ar2 are independently selected from an aromatic ring or a heterocyclic ring; X1 and X2 are independently selected from a single bond or a divalent linking group.

[0009] Furthermore, the diamine monomer containing a cyclobutane group includes at least one of the structures shown in Formula A1 to Formula A4:

[0010]

[0011]

[0012] Furthermore, the dianhydride monomer includes at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, isomeric diphenyl sulfide dianhydride, triphenyl diether dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-bisphenol A dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, and 2,3,5,6-pyromellitic dianhydride.

[0013] Furthermore, the number average molecular weight of the polyimide is 2×10 4 g / mol~1×10 5 g / mol, and the polydispersity index is 1.1 to 1.8.

[0014] Another object of the present invention is to provide a method for preparing a photosensitive polyimide, comprising the steps of:

[0015] (1) under a nitrogen atmosphere, adding the diamine monomer containing a cyclobutane group into an organic solvent and continuously stirring until it is completely dissolved;

[0016] (2) adding the dianhydride monomer to the solution obtained in step (1), continuously stirring, and reacting to obtain a photosensitive polyamic acid solution;

[0017] (3) Pre-drying and imidizing the photosensitive polyamic acid solution obtained in step (2) to obtain the photosensitive polyimide.

[0018] Furthermore, the organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylcaproamide, γ-butyrolactone, dimethyl sulfoxide, 1,3-dimethylpropyleneurea, and ethylene glycol butyl ether.

[0019] Furthermore, the molar ratio of the diamine monomer containing a cyclobutane group to the dianhydride monomer is 1:(0.9-1.1).

[0020] Furthermore, in the step (2), the reaction temperature is 10°C to 60°C, and the reaction time is 2h to 48h; and / or, in the step (3), the pre-drying temperature is 80°C to 120°C, and the pre-drying time is 60s to 150s; the imidization treatment temperature is 100°C to 300°C, and the time is 1h to 4h.

[0021] Another object of the present invention is to provide a polyimide film, which contains the photosensitive polyimide or the photosensitive polyimide prepared by the method for preparing the photosensitive polyimide.

[0022] Another object of the present invention is to provide a circuit board comprising the polyimide film.

[0023] The beneficial effects produced by the technical solution of the present invention include:

[0024] The present invention provides a photosensitive polyimide, a preparation method, a polyimide film and a circuit board. The photosensitive polyimide of the present invention is suitable for a KrF light source with a wavelength of 248 nm, has excellent adaptability to the manufacture of microscopic-sized structures, and can meet the manufacturing requirements of fine structures; in addition, the photosensitive polyimide of the present invention also has excellent etching resistance, a high retention rate, and can maintain high stability and reliability in a complex semiconductor manufacturing process. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be further described in detail below in conjunction with specific embodiments.

[0026] Unless otherwise defined, technical or scientific terms used in the disclosure of the present invention should have the common meanings that can be understood by those skilled in the art in the field to which the present invention belongs.

[0027] As analyzed in the background technology, in the prior art, the UV exposure wavelengths of common polyimide photoresists are mainly concentrated in the i-line (365nm) and the g-line (436nm), and the shorter wavelength KrF (248nm) is rarely involved; however, the i-line photoresist and the g-line photoresist can only be used for semiconductor processes with a process of more than 350nm, and cannot be used for applications with a process of less than 350nm, and cannot meet the manufacturing requirements of micro-sized fine structures. To solve this problem, the present invention provides a photosensitive polyimide, a preparation method, a polyimide film and a circuit board.

[0028] In a typical embodiment of the present application, a photosensitive polyimide is provided, wherein the photosensitive polyimide is obtained by polymerizing a dianhydride monomer and a diamine monomer containing a cyclobutane group and then imidizing the dianhydride monomer, wherein the diamine monomer containing a cyclobutane group has a structure shown in Formula 1:

[0029]

[0030] The cyclobutane group will undergo photolysis when exposed to ultraviolet light, especially deep ultraviolet light with a wavelength of 248nm. The cyclobutane group is introduced into the diamine monomer and polymerized with the dianhydride monomer to form a photosensitive polyimide containing cyclobutane groups in the main chain structure through imidization. When ultraviolet exposure is performed, the cyclobutane group in the main chain of the photosensitive polyimide in the area irradiated by ultraviolet light will undergo lysis, while the unexposed part blocked by the mask will maintain its structure. At this time, the photosensitive polyimide film can be developed with an appropriate solvent and other operations can be performed to obtain the desired pattern.

[0031] Among them, R1 is selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms, or a divalent linking group that forms a part of a bond to Ar1 to form a ring; R4 is selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms, or a divalent linking group that forms a part of a bond to Ar2 to form a ring; R2, R3, R5 and R6 are independently selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms; Ar1 ​​and Ar2 are independently selected from an aromatic ring or a heterocyclic ring; X1 and X2 are independently selected from a single bond or a divalent linking group.

[0032] Specifically, when R1 is selected from a divalent linking group that forms a bond to Ar1 or R4 is selected from a divalent linking group that forms a bond to Ar2, there is no particular restriction on the bonding position of the divalent linking group to Ar1 and Ar2, and it only needs to comply with the rules of chemical bonding and be a stable structure. When X1 and X2 are independently selected from divalent linking groups, the divalent linking groups here can be exemplified by: -CH2-, -O-, -S-, -SO2-.

[0033] Furthermore, the diamine monomer containing a cyclobutane group includes at least one of the structures shown in Formula A1 to Formula A4:

[0034] Compared with other structures, the structures shown in Formula A1 to Formula A4 are simple, easy to obtain and low in cost.

[0035] Furthermore, the dianhydride monomer has no additional requirements, and common dianhydrides can be used. Specifically, the dianhydride monomer includes at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, isomeric diphenyl sulfide dianhydride, triphenyl diether dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-bisphenol A dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, and 2,3,5,6-pyromellitic dianhydride.

[0036] Furthermore, the number average molecular weight of the polyimide is 2×10 4 g / mol~1×10 5 g / mol, and the polydispersity index is 1.1 to 1.8. If the number average molecular weight is too high, the photoresist will not be fully developed after exposure at the same energy, and the non-exposed area cannot be completely removed; if the number average molecular weight is too low, the photoresist film will not be able to resist development after exposure, and the pattern cannot be formed. Preferably, the number average molecular weight of the polyimide is 5×10 4 g / mol~8×10 4 g / mol, and the polydispersity index is 1.3 to 1.6.

[0037] In a typical embodiment of the present application, a method for preparing a photosensitive polyimide is provided, comprising the steps of:

[0038] (1) under a nitrogen atmosphere, adding the diamine monomer containing a cyclobutane group into an organic solvent and continuously stirring until it is completely dissolved;

[0039] (2) adding the dianhydride monomer to the solution obtained in step (1), continuously stirring, and reacting to obtain a photosensitive polyamic acid solution;

[0040] (3) Pre-drying and imidizing the photosensitive polyamic acid solution obtained in step (2) to obtain the photosensitive polyimide.

[0041] Furthermore, the organic solvent has no additional requirements, and a common organic solvent that can dissolve the above-mentioned diamine monomer and dianhydride monomer can be used. Specifically, the organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylcaproamide, γ-butyrolactone, dimethyl sulfoxide, 1,3-dimethylpropyleneurea, and ethylene glycol butyl ether.

[0042] Furthermore, the molar ratio of the diamine monomer containing a cyclobutane group to the dianhydride monomer is 1:(0.9-1.1). Within the above range, the molar ratio can ensure that the monomer reaction is complete and the yield meets the requirements, and it is also convenient to control the molecular weight. Too high or too low a molar ratio will cause the polymer molecular weight to deviate from expectations. Preferably, the molar ratio of the diamine monomer containing a cyclobutane group to the dianhydride monomer is 1:1.

[0043] Furthermore, in step (2), the reaction temperature is 10°C to 60°C, and the reaction time is 2h to 48h; the viscosity of the reaction system is continuously monitored during the reaction, and when the viscosity of the system no longer changes, the reaction is considered to be complete and the next step can be carried out. Too low a reaction temperature is not conducive to the reaction, while too high a reaction temperature may cause the molecular weight to grow too fast; too long a reaction time may cause the polymer to decompose, while too short a reaction time may not reach the required molecular weight; in short, the target molecular weight cannot be obtained under unreasonable temperature and time conditions. And / or, in step (3), the pre-drying temperature is 80°C to 120°C, and the pre-drying time is 60s to 150s; too high a pre-drying temperature and too long a pre-drying time may cause premature imidization of the polyamic acid, while too low a temperature and too short a time may not completely remove the solvent in the membrane; after the pre-drying is completed, the membrane surface should be clean and bright, and no fingerprints should be left when touched with a finger. In the step (3), the imidization treatment temperature is 100°C to 300°C, and the time is 1h to 4h; if the imidization temperature is too low or the time is too short, the polyamic acid cannot be completely imidized, and the system will be a mixture of polyamic acid-polyimide, which will have an adverse effect on subsequent tests; if the temperature is too high or the time is too long, the polyimide structure will be easily destroyed, and the desired polyimide film cannot be obtained.

[0044] Another object of the present invention is to provide a polyimide film, which contains the photosensitive polyimide or the photosensitive polyimide prepared by the method for preparing the photosensitive polyimide.

[0045] Furthermore, the polyimide film is obtained by coating the photosensitive polyamic acid solution obtained in step (2) on a substrate, pre-drying and imidizing the substrate.

[0046] Furthermore, there is no special requirement for the substrate, and this case does not impose any limitation thereto, and any conventional substrate film can be used, such as polyethylene terephthalate film, polyethylene naphthalate film, and the like.

[0047] Furthermore, the thickness of the polyimide film is 10 micrometers to 20 micrometers.

[0048] Furthermore, the polyimide film is prepared by coating the photosensitive polyamic acid solution obtained in step (2) on a substrate, pre-drying and imidizing to obtain a cured film, exposing it to ultraviolet light with a wavelength of 248 nm under a mask, and then cleaning and drying it to obtain a polyimide pattern film.

[0049] Furthermore, the exposure energy is 200 mJ / cm 2 ~1000mJ / cm 2 . Preferably 400mJ / cm 2 ~800mJ / cm 2 .

[0050] Furthermore, the solvent used for cleaning includes at least one of methanol, ethanol, ethyl acetate, dichloromethane and ultrapure water; preferably methanol and ultrapure water.

[0051] Furthermore, the drying temperature is 80° C. to 100° C., and the drying time is 30s to 60s. The purpose of drying here is to remove the residual solvent in the washing step, so the drying time is generally shorter than the pre-drying time before the imidization treatment.

[0052] Another object of the present invention is to provide a circuit board comprising the polyimide film.

[0053] Furthermore, the method for preparing the circuit board comprises coating the photosensitive polyamic acid solution obtained in step (2) on a copper-clad laminate, pre-drying and imidizing the cured film to obtain a cured film, exposing the cured film to ultraviolet light with a wavelength of 248 nm under a mask, and then cleaning and drying the cured film to obtain the circuit board containing the polyimide film; or, the method for preparing the circuit board comprises bonding the polyimide film to the copper-clad laminate by hot rolling, vacuum lamination, etc., exposing the cured film to ultraviolet light with a wavelength of 248 nm under a mask, and then cleaning and drying the cured film to obtain the circuit board containing the polyimide film.

[0054] The beneficial effects of the present application will be further illustrated below in combination with embodiments and comparative examples.

[0055] Synthesis Example 1: Synthesis of diamine monomer A1

[0056]

[0057] Add 800 mL of acetone, 20 mL of 5% hydrochloric acid and 65.2 g of 4-aminocinnamic acid into a 1 L quartz flask, install a condenser and a 100 W high pressure mercury lamp, and irradiate for 48 hours at a power of 2.7 mW / cm2. After the reaction is completed, filter, wash and dry to obtain 60 g of compound A1-1;

[0058] In a 500 mL three-necked flask under nitrogen atmosphere, add 40 g of compound A1-1, 200 mL of thionyl chloride and 2 mL of N,N-dimethylformamide, and reflux for 2 hours. After the reaction, evaporate the crystals and recrystallize them with tetrahydrofuran, and filter and dry to obtain 34.8 g of compound A1-2;

[0059] In a nitrogen atmosphere, add 34.8 g of compound A1-2 and 400 mL of toluene to a 1L three-necked flask, control the reaction temperature below 5°C with an ice bath, slowly drop 5M decane solution of tert-butyl hydroperoxide, and then slowly drop 6.4 mL of pyridine. After the reaction is completed, add 5% hydrochloric acid and 5% potassium hydroxide aqueous solution for washing, and finally wash three times with ultrapure water; then add magnesium sulfate to dry and evaporate the crystals, then recrystallize with a mixture of ethyl acetate and hexane, and filter and dry to obtain 30.2 g of compound A1-3.

[0060] In a nitrogen atmosphere, 500 mL of isopropyl toluene and 15.1 g of compound A1-3 were added to a 1 L three-necked flask, and the mixture was refluxed at 150 ° C for 12 hours. After the reaction, the mixture was concentrated to 150 mL and precipitated in 1.5 L of methanol. The precipitate was collected and dissolved in tetrahydrofuran, purified with a silica column (developing solvent: chloroform: ethanol = 9:1 (mass ratio)), and evaporated, crystallized, and dried to obtain 4.6 g of diamine monomer A1.

[0061] Synthesis Example 2: Synthesis of diamine monomer A2

[0062]

[0063] In a 500 mL three-necked flask under nitrogen atmosphere, 4 g of potassium metal, 192 g of methylcyclohexane, and 48 g of ββ-methylphenylethylene were added, and the mixture was refluxed at 100° C. for 4 hours. After the reaction, the mixture was purified by rotary evaporation to obtain 21.2 g of compound A2-1.

[0064] In a 1L three-necked flask under nitrogen atmosphere, 21.2 g of compound A2-1 and 49.2 g of nitric acid were added and refluxed at 80°C for 8 hours. After the reaction, 600 mL of ice water was added to precipitate, and the precipitate was washed with ultrapure water and recrystallized with ethanol to obtain 27.9 g of compound A2-2.

[0065] In a 1L three-necked flask under a nitrogen atmosphere, 27.9 g of compound A2-2, 0.7 g of 5% palladium carbon, 200 mL of tetrahydrofuran, 200 mL of ethanol, and 16.6 g of hydrazine hydrate were added, and the mixture was refluxed at 70°C for 2 hours. After the reaction, the mixture was filtered with diatomaceous earth and the filtrate was concentrated to 100 mL by rotary evaporation, and then 400 mL of ethyl acetate was added. The mixture was washed three times with ultrapure water, evaporated, crystallized, and vacuum dried to obtain 20.6 g of diamine monomer A2.

[0066] Synthesis Example 3: Synthesis of diamine monomer A3

[0067]

[0068] Add 300 mL of benzene, 20 mL of 5% hydrochloric acid, 116 g of indene and 10 g of benzophenone to a 1L quartz flask, install a condenser and a 100W high-pressure mercury lamp, and irradiate for 48 hours at a power of 2.7 mW / cm2. After the reaction is completed, distill and concentrate under reduced pressure, purify using a silica column (developing solvent: hexane), recrystallize with acetone, filter and dry to obtain compound A3-170 g;

[0069] In a nitrogen atmosphere, add 70 g of compound A3-1 and 160 mL of concentrated sulfuric acid to a 1L three-necked flask, control the reaction temperature below 10°C with an ice bath, and slowly drop 49.2 mL of a mixture of concentrated sulfuric acid and concentrated nitric acid. Add 540 g of ice cubes and return to room temperature for filtration, wash the eluate with ethanol, and purify it using a silica column (developing solvent: chloroform: ethanol = 9:10) to obtain 48.3 g of compound A3-2;

[0070] In a nitrogen atmosphere, 48.3 g of compound A3-2, 500 mL of tetrahydrofuran, 250 mL of ethanol, and 2.4 g of 5% palladium on carbon were added to a 1L three-necked flask, and 65 mL of hydrazine hydrate was slowly added dropwise, and the mixture was refluxed at 65° C. for 2 hours. After the reaction, the filtrate was concentrated by rotary evaporation and purified by a silica column (developing solvent: chloroform: ethanol = 7:3), and 26.2 g of diamine monomer A3 was obtained by evaporation, crystallization, and drying.

[0071] Synthesis Example 4: Synthesis of diamine monomer A4

[0072]

[0073] In a nitrogen atmosphere, 8 g of compound A1-1 and 80 mL of concentrated sulfuric acid were added to a 250 mL three-necked flask, and the mixture was refluxed at 140° C. for 6 hours. After returning to room temperature, the reaction solution was poured into 1 L of ethyl diether to precipitate and collect the precipitate, which was dispersed in 200 mL of tetrahydrofuran and washed twice with 1 M potassium hydroxide aqueous solution. 200 mL of ethyl acetate was added to the organic layer, and the mixture was washed three times with ultrapure water, then evaporated and crystallized, recrystallized with dimethylacetamide, filtered and dried, and 44.6 g of diamine monomer A was obtained.

[0074] Example 1: Synthesis of photosensitive polyimide PAA1

[0075] In a nitrogen atmosphere, 23.8 g of diamine monomer A1 and 300 g of N-methylpyrrolidone (NMP) were added to a 500 mL three-necked flask. After being fully stirred and dissolved, 31 g of dianhydride monomer 4,4'-oxydiphthalic anhydride was gradually added, and rinsed with 65 g of NMP. After continuous stirring and reaction at room temperature for 12 hours, the photosensitive polyimide was obtained; the molar ratio of the diamine monomer to the dianhydride monomer was 1:1.

[0076] The photosensitive polyimide was spin-coated on the surface of the substrate, pre-baked at 100°C for 90 seconds, and then cured at 230°C for 2 hours to obtain a photosensitive polyimide film. The number average molecular weight of the photosensitive polyimide was 6.0×10 4 g / mol, and the polydispersity index is 1.35. Continue to expose it to UV light, and the exposure energy is 500mJ / cm 2 , followed by immersion development with methanol for 300 s, and then rinsing with ultrapure water and drying to obtain a pattern.

[0077] The film retention rate, resolution, and UV exposure sensitivity of PAA1 are shown in Table 1.

[0078] Example 2: Synthesis of photosensitive polyimide PAA2

[0079] In a nitrogen atmosphere, 26.6 g of diamine monomer A2 and 320 g of N-methylpyrrolidone (NMP) were added to a 500 mL three-necked flask. After being fully stirred and dissolved, 31 g of dianhydride monomer 4,4'-oxydiphthalic anhydride was gradually added, and rinsed with 65 g of NMP. After continuous stirring and reaction at room temperature for 16 hours, the photosensitive polyimide was obtained; the molar ratio of the diamine monomer to the dianhydride monomer was 1:1.

[0080] The photosensitive polyimide was spin-coated on the surface of the substrate, pre-baked at 100°C for 90 seconds, and cured at 230°C for 2 hours to obtain a photosensitive polyimide film. The number average molecular weight of the photosensitive polyimide was 6.5×10 4 g / mol, and the polydispersity index is 1.42. Continue to expose it to UV light, and the exposure energy is 300mJ / cm 2 , followed by immersion development with methanol for 270 s, and then rinsing with ultrapure water and drying to obtain a pattern.

[0081] The film retention rate, resolution, and UV exposure sensitivity of PAA2 are shown in Table 1.

[0082] Example 3: Synthesis of photosensitive polyimide PAA3

[0083] In a nitrogen atmosphere, 26.2 g of diamine monomer A3 and 320 g of N-methylpyrrolidone (NMP) were added to a 500 mL three-necked flask. After being fully stirred and dissolved, 31 g of dianhydride monomer 4,4'-oxydiphthalic anhydride was gradually added, and rinsed with 65 g of NMP. After continuous stirring and reaction at room temperature for 12 hours, the photosensitive polyimide was obtained; the molar ratio of the diamine monomer to the dianhydride monomer was 1:1.

[0084] The photosensitive polyimide was spin-coated on the surface of the substrate, pre-baked at 100°C for 90 seconds, and then cured at 230°C for 2 hours to obtain a photosensitive polyimide film. The number average molecular weight of the photosensitive polyimide was 7.5×10 4 g / mol, and the polydispersity index is 1.39. Continue to expose it to UV light, and the exposure energy is 350mJ / cm 2 , followed by immersion development with methanol for 300 s, and then rinsing with ultrapure water and drying to obtain a pattern.

[0085] The film retention rate, resolution, and UV exposure sensitivity of PAA3 are shown in Table 1.

[0086] Example 4: Synthesis of photosensitive polyimide PAA4

[0087] In a nitrogen atmosphere, 29.0 g of diamine monomer A4 and 350 g of N-methylpyrrolidone (NMP) were added to a 1L three-necked flask. After being fully stirred and dissolved, 31 g of dianhydride monomer 4,4'-oxydiphthalic anhydride was gradually added, and rinsed with 50 g of NMP. After continuous stirring and reaction at room temperature for 18 hours, the photosensitive polyimide was obtained; the molar ratio of the diamine monomer to the dianhydride monomer was 1:1.

[0088] The photosensitive polyimide was spin-coated on the surface of the substrate, pre-baked at 100°C for 90 seconds, and then cured at 230°C for 2 hours to obtain a photosensitive polyimide film. The number average molecular weight of the photosensitive polyimide was 6.9×10 4 g / mol, and the polydispersity index is 1.58. Continue to expose it to UV light, and the exposure energy is 250mJ / cm 2 , followed by immersion development with methanol for 240 s, and then rinsing with ultrapure water and drying to obtain a pattern.

[0089] The film retention rate, resolution, and UV exposure sensitivity of PAA4 are shown in Table 1.

[0090] Example 5: Synthesis of photosensitive polyimide PAA5

[0091] The difference from Example 1 is that the diamine monomer A1 is 23.8 g, the dianhydride monomer 4,4'-oxydiphthalic anhydride is 34.1 g, and the molar ratio of the diamine monomer to the dianhydride monomer is 1:1.1.

[0092] The number average molecular weight of photosensitive polyimide is 5.5×10 4 g / mol, and the polydispersity index was 1.52.

[0093] The film retention rate, resolution, and UV exposure sensitivity of PAA6 are shown in Table 1.

[0094] Example 6: Synthesis of photosensitive polyimide PAA6

[0095] The difference from Example 1 is that the diamine monomer A1 is 23.8 g, the dianhydride monomer 4,4'-oxydiphthalic anhydride is 27.9 g, and the molar ratio of the diamine monomer to the dianhydride monomer is 1:0.9.

[0096] The number average molecular weight of photosensitive polyimide is 5.3×10 4 g / mol, and the polydispersity index was 1.55.

[0097] The film retention rate, resolution, and UV exposure sensitivity of PAA5 are shown in Table 1.

[0098] Example 7: Synthesis of photosensitive polyimide PAA7

[0099] The difference from Example 1 is that the diamine monomer A1 is 23.8 g, the dianhydride monomer 4,4'-oxydiphthalic anhydride is 31 g, and the molar ratio of the diamine monomer to the dianhydride monomer is 1:1.

[0100] The number average molecular weight of photosensitive polyimide is 8×10 4 g / mol, and the polydispersity index was 1.41.

[0101] The film retention rate, resolution, and UV exposure sensitivity of PAA7 are shown in Table 1.

[0102] Example 8: Synthesis of photosensitive polyimide PAA8

[0103] The difference from Example 1 is that the diamine monomer A1 is 23.8 g, the dianhydride monomer 4,4'-oxydiphthalic anhydride is 31 g, and the molar ratio of the diamine monomer to the dianhydride monomer is 1:1.

[0104] The number average molecular weight of photosensitive polyimide is 5×10 4 g / mol, and the polydispersity index was 1.33.

[0105] The film retention rate, resolution, and UV exposure sensitivity of PAA8 are shown in Table 1.

[0106] Comparative Example 1: Synthesis of photosensitive polyimide PAA9

[0107] In a nitrogen atmosphere, 20.0 g of diamine monomer 4,4'-diaminodiphenyl ether and 300 g of N-methylpyrrolidone (NMP) were added to a 500 mL three-necked flask. After being fully stirred and dissolved, 31 g of dianhydride monomer 4,4'-oxydiphthalic anhydride was gradually added, and rinsed with 65 g of NMP. After continuous stirring and reaction at room temperature for 12 hours, the photosensitive polyimide was obtained; the molar ratio of the diamine monomer to the dianhydride monomer was 1:1.

[0108] The photosensitive polyimide was spin-coated on the surface of the substrate, pre-baked at 100°C for 90 seconds, and then cured at 230°C for 2 hours to obtain a photosensitive polyimide film. The number average molecular weight of the photosensitive polyimide was 7.0×10 4 g / mol. Continue to expose it to UV light with an exposure wavelength of 365nm and an exposure energy of 1000mJ / cm 2 , followed by immersion development with methanol for 600 s, and then rinsing with ultrapure water and drying to obtain a pattern.

[0109] The film retention rate, resolution, and UV exposure sensitivity of PAA9 are shown in Table 1.

[0110] Hereinafter, the sample evaluation methods and evaluation results of Examples and Comparative Examples will be described.

[0111]

Film retention rate evaluation

[0112] Use a knife to gently scratch a notch on the surface of the polyimide film, use a step profiler to measure the film thickness before exposure and development as d0, and measure the film thickness at the same position after exposure and development as d1. The film retention rate is: d1 / d0×100%.

[0113]

Resolution evaluation

[0114] The photosensitive polyamic acid solution prepared in the embodiment and the comparative example is spin-coated on a substrate, pre-baked at 100°C for 90s, and then cured at 230°C for 2 hours; the cured photosensitive polyimide film is exposed under ultraviolet light with a wavelength of 248nm under a mask (Comparative Example 1 cannot be exposed under ultraviolet light with a wavelength of 248nm, and ultraviolet light with a wavelength of 365nm is actually used for exposure), and then washed and dried to obtain a pattern. The pattern is observed under a microscope, and the minimum value of the line width that can completely remove the exposed part and remain without distortion or defect in the line is recorded as the resolution value. The smaller the value, the better the resolution.

[0115]

Evaluation of UV exposure sensitivity

[0116] The prepared polyimide film surface is exposed, developed, cleaned and dried at an energy gradient of 25mJ from 50mJ to 1000mJ to obtain a pattern. The pattern is observed under a microscope, and the minimum value of the line width remaining after the exposed part is completely removed without distortion or defect is recorded as the UV exposure sensitivity value. The smaller the value, the higher the UV exposure sensitivity.

[0117]

Evaluation results

[0118] The evaluation results of the embodiments and comparative examples are shown in Table 1.

[0119] Table 1: Film retention rate, resolution and UV exposure sensitivity of each group of examples

[0120]

[0121] As shown in Table 1, the photosensitive polyimides prepared in Examples 1-8 can all be exposed under KrF (248 nm), and their performances such as resolution and film retention rate are better than those in Comparative Example 1.

[0122] In summary, the photosensitive polyimide, preparation method, and polyimide film of the present invention are beneficial for meeting the manufacturing requirements of micro-sized structures, improving etching resistance and retention rate, and maintaining high stability and reliability, and have good industrial applicability.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A photosensitive polyimide, characterized in that: The photosensitive polyimide is prepared by polymerization of a dianhydride monomer and a diamine monomer containing a cyclobutane group and imidization, wherein the diamine monomer containing a cyclobutane group has a structure shown in Formula 1: Among them, R1 is selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms, or a divalent linking group that forms a part of a bond to Ar1 to form a ring; R4 is selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms, or a divalent linking group that forms a part of a bond to Ar2 to form a ring; R2, R3, R5 and R6 are independently selected from a hydrogen atom, an alkyl group of 1 to 3 carbon atoms; Ar1 ​​and Ar2 are independently selected from an aromatic ring or a heterocyclic ring; X1 and X2 are independently selected from a single bond or a divalent linking group.

2. A photosensitive polyimide according to claim 1, characterized in that: The diamine monomer containing a cyclobutane group includes at least one of the structures shown in Formula A1 to Formula A4:

3. A photosensitive polyimide according to claim 1, characterized in that: The dianhydride monomer includes at least one of pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, isomeric diphenyl sulfide dianhydride, triphenyl diether dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-bisphenol A dianhydride, 3,3',4,4'-diphenyl sulfone tetracarboxylic dianhydride, and 2,3,5,6-pyromellitic dianhydride.

4. A photosensitive polyimide according to claim 1, characterized in that: The number average molecular weight of the polyimide is 2×10 4 g / mol~1×10 5 g / mol, and the polydispersity index is 1.1 to 1.

8.

5. The method for preparing a photosensitive polyimide according to any one of claims 1 to 4, characterized in that: Includes steps: (1) under a nitrogen atmosphere, adding the diamine monomer containing a cyclobutane group into an organic solvent and continuously stirring until it is completely dissolved; (2) adding the dianhydride monomer to the solution obtained in step (1), continuously stirring, and reacting to obtain a photosensitive polyamic acid solution; (3) Pre-drying and imidizing the photosensitive polyamic acid solution obtained in step (2) to obtain the photosensitive polyimide.

6. The method for preparing photosensitive polyimide according to claim 5, characterized in that: The organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylcaproamide, γ-butyrolactone, dimethyl sulfoxide, 1,3-dimethylpropyleneurea, and ethylene glycol butyl ether.

7. The method for preparing photosensitive polyimide according to claim 5, characterized in that: The molar ratio of the diamine monomer containing a cyclobutane group to the dianhydride monomer is 1:(0.9-1.1).

8. The method for preparing photosensitive polyimide according to claim 5, characterized in that: In the step (2), the reaction temperature is 10°C to 60°C, and the reaction time is 2h to 48h; and / or, in the step (3), the pre-drying temperature is 80°C to 120°C, and the pre-drying time is 60s to 150s; the imidization treatment temperature is 100°C to 300°C, and the time is 1h to 4h.

9. A polyimide film, characterized in that: The polyimide film contains the photosensitive polyimide according to any one of claims 1 to 4, or contains the photosensitive polyimide prepared by the method for preparing the photosensitive polyimide according to any one of claims 5 to 8.

10. A circuit board, characterized in that: The circuit board comprises the polyimide film according to claim 9.

Images