Photosensitive polyimide, preparation method thereof, photoresist and polyimide film

Abstract

The invention provides photosensitive polyimide, a preparation method of the photosensitive polyimide, photoresist and a polyimide film. The photosensitive polyimide has a structure as shown in a formula I, the prepared photoresist can be developed by using a neutral aqueous solution, can realize a positive photoetching pattern, and can be cured at a low temperature lower than 200 DEG C. The patterned film layer has good mechanical properties: Young modulus gt; 3.0 GPa, tensile strength gt; the elongation at break is gt under the pressure of 150 MPa; the preparation resolution ratio is 1t; and the 5-micron thin film meets the application requirements on high mechanical property, low-temperature curing and high resolution when being used as an insulating layer, a passivation layer or an interlayer dielectric layer and the like in the semiconductor industry.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polyimide, and particularly relates to a photosensitive polyimide, a preparation method thereof, a photoresist, and a polyimide film. BACKGROUND

[0002] A photosensitive polyimide (PSPI) composition is a photoresist material containing a polyimide resin and a photosensitive component, which can undergo a photochemical reaction under ultraviolet exposure to form a dissolution rate difference between an exposed area and a non-exposed area, realizing photoetching patterning. PSPI has both the characteristics of photoresist and the functionality of polyimide. It has excellent heat resistance, mechanical properties, dielectric properties, and chemical resistance of traditional polyimide (PI) materials, and is widely used in semiconductor devices, integrated circuits, micro-electro-mechanical systems (MEMS), new displays, and other fields, showing more and more prominent importance as a practical dielectric insulating material or structural material.

[0003] In recent years, with the portability and high performance of various electronic devices such as smart phones, portable computers, and AR devices, the requirements for smaller, thinner, and higher density of semiconductor devices have also rapidly increased. Therefore, from the perspective of improving integration and computing function, the packaging structure of integrated circuits is changing. Wafer-level packaging and three-dimensional stacking, such as advanced packaging technologies with high density, are rapidly developing. In such advanced packaging technologies, photosensitive polyimides that can form patterns on chips and substrates are used as protective films, insulating layers, and dielectric layers, and their insulating properties, mechanical strength, heat resistance, and adhesion to substrates continue to be of concern. In these application scenarios, by covering the semiconductor chip with a photosensitive polyimide to form an insulating dielectric layer larger than the semiconductor chip, and then patterning, a rewiring layer can be constructed by depositing metal to form a multi-layer stacked chip package. In order to achieve planarization and precise interconnection of the multi-layer chip surface, PSPI as an interlayer planarization and insulating dielectric layer needs to ensure an opening size of <10 microns, and also needs to be cured at a low temperature, because too high a curing temperature can easily cause interlayer stress and in-plane non-uniformity, resulting in problems such as cracking and warping. On the other hand, high temperatures can also cause the copper of the rewiring to be oxidized. Therefore, advanced packaging technologies require a reduction in the curing temperature of PSPI. These scenarios often require high mechanical properties of the cured film at a curing temperature of less than 200 degrees.

[0004] As for photosensitive polyimide materials, a polyimide precursor, polyamic acid derivative, is usually used, for example, a polyimide precursor in which an acrylate group is introduced through an ester bond or an ionic bond from the carboxyl group of polyamic acid. After patterning, an imidization reaction needs to be carried out at a high temperature of more than 350 degrees in order to obtain the target polyimide. Reducing the curing temperature can result in incomplete imidization, which not only has poor heat resistance, but also insufficient mechanical properties. SUMMARY

[0005] Therefore, the present application aims to provide a photosensitive polyimide, a preparation method thereof, a photoresist and a polyimide film, the photoresist prepared from the photosensitive polyimide can be developed by using a neutral aqueous solution, a positive photoetching pattern can be realized, and the photoresist can be cured at a low temperature below 200 DEG C; the patterned film layer has good mechanical properties: Young's modulus > 3.0 GPa, tensile strength > 150 MPa, and elongation at break > 60%, and a film with a resolution < 5 microns can be prepared.

[0006] The present application provides a photosensitive polyimide having a structure of formula I:

[0007] Formula I;

[0008] X is a residue of a polyimide polymerization monomer tetracarboxylic dianhydride;

[0009] Y is a residue of a polyimide polymerization monomer diamine;

[0010] At least one of X and Y comprises a tertiary amine structure;

[0011] n is 2-150.

[0012] Preferably, the tertiary amine structure is selected from a nitrogen-containing aromatic heterocyclic structure, a nitrogen-containing heterocyclic structure or a tri-substituted amine structure;

[0013] The nitrogen-containing aromatic heterocyclic structure is selected from pyridine, pyridazine, pyrimidine, pyrazine, triazine, imidazole, oxazole, oxadiazole, thiazole, pyrazole, indole, quinoline, isoquinoline, purine, benzimidazole or benzoxazole;

[0014] The nitrogen-containing heterocyclic structure is selected from piperidine, piperazine, pyrrolidine or morpholine;

[0015] The tri-substituted amine structure has a structure of formula II:

[0016] Formula II;

[0017] R1, R2 or R3 is selected from C1-C40 alkyl or aryl.

[0018] Preferably, R1, R2 or R3 is independently selected from C1-C40 alkyl and its derivative with a substituent, C3-C20 alicyclic group and its derivative with a substituent, C3-C30 heterocyclic group and its derivative with a substituent, or C5-C30 aromatic group and its derivative with a substituent;

[0019] said substituents are independently selected from hydrogen, alkyl, cycloalkyl, aryl, fluoroalkyl, hydroxy, alkoxy, phenoxy, cyano, nitro, amino, acetylamino, ester, acyl, halo, or carboxyl.

[0020] Preferably, X is selected from a nitrogen-containing aromatic heterocyclic ring structure or a nitrogen-containing heterocyclic ring structure in a tertiary amine structure, X is selected from any one of the following:

[0021] Formula 101, Formula 102, Formula 103, Formula 104, Formula 105, Formula 106, Formula 107, Formula 108, Formula 109, Formula 110, Formula 111, Formula 112, Formula 113, Formula 114, Formula 115, Formula 116, Formula 117, Formula 118;

[0022] Z in Formulae 103-118 is independently selected from any one or more of the following groups:

[0023] a chemical bond, , , , , , , , , , ;

[0024] R in Formulae 115 and 116 n is independently selected from C1-C40 alkyl and its substituted derivatives, C3-C20 alicyclic group and its substituted derivatives, C3-C30 heterocyclic group and its substituted derivatives, or C5-C30 aromatic group and its substituted derivatives.

[0025] Preferably, Y is selected from a nitrogen-containing aromatic heterocyclic ring structure or a nitrogen-containing heterocyclic ring structure in a tertiary amine structure, Y is selected from any one of the following:

[0026] Formula 201, Formula 202, Formula 203, Formula 204 Formula 205 Formula 206 Formula 207 Formula 208 Formula 209 Formula 210 Formula 211 Formula 212 Formula 213 Formula 214 Formula 215

[0027] Formula 216 Formula 217 Formula 218 Formula 219 Formula 220 Formula 221 Formula 222 Formula 223

[0028] R in Formula 203, Formula 220, Formula 221 n independently selected from C1-C40 alkyl groups and groups bearing substituents thereon, C3-C20 alicyclic groups and groups bearing substituents thereon, C3-C30 heterocyclic groups and groups bearing substituents thereon, or C5-C30 aromatic groups and groups bearing substituents thereon;

[0029] Z in said Formulae 204 to 223 is independently selected from any one or more of the following groups:

[0030] a chemical bond, , , , , , , , , , .

[0031] Preferably, X is selected from a tri-substituted amine structure in a tertiary amine structure, X is selected from any one of the following:

[0032] Formula 301 Formula 302 Formula 303 Formula 304 or Formula 305

[0033] Y is selected from a tri-substituted amine structure in a tertiary amine structure, Y is selected from any one of the following:

[0034] Formula 401, Formula 402, Formula 403, Formula 404, Formula 405, Formula 406;

[0035] R in Formula 303, Formula 401-Formula 405 m the substituent is independently selected from alkyl, fluoroalkyl, aryl, substituted aryl, carboxyl, nitro, alkoxy, acetyl or hydroxyl;

[0036] R6 in Formula 301-Formula 305, Formula 401-Formula 406 is independently selected from C1-C40 alkyl and its substituted derivative, C3-C20 alicyclic group and its substituted derivative, C3-C30 heterocyclic group and its substituted derivative or C5-C30 aromatic group and its substituted derivative.

[0037] The application provides a preparation method of the photosensitive polyimide, comprising the following steps:

[0038] mixing monomer tetracarboxylic dianhydride, monomer diamine and solvent, and performing polycondensation reaction to obtain polyamic acid;

[0039] performing imidization reaction on the polyamic acid to obtain the photosensitive polyimide.

[0040] Preferably, the temperature of the polycondensation reaction is <20℃; and the time of the polycondensation reaction is 4-24h;

[0041] The imidization reaction is thermal imidization reaction or chemical imidization reaction;

[0042] The thermal imidization reaction uses a second solvent which is azeotropic with water;

[0043] The chemical imidization reaction uses a dehydrating agent.

[0044] The application provides a photoresist, comprising 100 parts of the photosensitive polyimide, 50-200 parts of an acidic compound, 2-50 parts of a photosensitive auxiliary agent, 100-300 parts of a solvent, 0.1-5 parts of a leveling agent and 0.1-10 parts of an adhesion promoter by mass fraction.

[0045] The application provides a polyimide film prepared by the following method:

[0046] The photoresist is coated, pre-baked, exposed, developed and heat-cured to obtain the polyimide film.

[0047] The application provides a photosensitive polyimide with the structure of formula I; a photoresist prepared from the photosensitive polyimide can be developed by using a neutral aqueous solution, and can realize positive photoetching patterns, and can be cured at a low temperature below 200 DEG C. The patterned film layer has good mechanical properties: Young's modulus > 3.0 GPa, tensile strength > 150 MPa, and elongation at break > 60%, and can be used to prepare a thin film with a resolution < 5 microns, and can meet the application requirements of high mechanical properties, low temperature curing and high resolution in the application scenarios of the semiconductor industry as an insulating layer, a passivation layer or an interlayer dielectric layer and the like. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 A route diagram for preparing the polyimide resin of the application;

[0049] Figure 2 A pattern with a photoetching resolution of 2 microns obtained from example 1 of the application;

[0050] Figure 3 An infrared spectrum of the PI resin obtained from example 1 of the application;

[0051] Figure 4 A pattern with a photoetching resolution of 3 microns obtained from example 2 of the application. DETAILED DESCRIPTION

[0052] The application provides a photosensitive polyimide with the structure of formula I:

[0053] Formula I;

[0054] The X is a residue of a polyimide polymerization monomer tetracarboxylic dianhydride;

[0055] The Y is a residue of a polyimide polymerization monomer diamine;

[0056] The X and Y at least one contains a tertiary amine structure;

[0057] The value of n is 2-150.

[0058] In the application, at least one structure in the X and Y structure contains a tertiary amine structure. That is, at least one of the monomers of the polyimide, tetracarboxylic dianhydride or diamine, contains a tertiary amine structure.

[0059] The tertiary amine structure in the application is preferably selected from a nitrogen-containing aromatic heterocyclic structure, a nitrogen-containing heterocyclic structure or a tri-substituted amine structure;

[0060] The nitrogen-containing aromatic heterocyclic structure is selected from pyridine, pyridazine, pyrimidine, pyrazine, triazine, imidazole, oxazole, oxadiazole, thiazole, pyrazole, indole, quinoline, isoquinoline, purine, benzimidazole or benzoxazole;

[0061] The nitrogen-containing heterocyclic structure is selected from piperidine, piperazine, pyrrolidine, or morpholine;

[0062] The tri-substituted amine structure has the structure of Formula II:

[0063] Formula II;

[0064] R1, R2, or R3 is selected from C1-C40 alkyl or aryl, i.e., substituted or unsubstituted aromatic, alicyclic, heterocyclic, or aliphatic groups, and can contain one or more of the heteroatoms, such as nitrogen, oxygen, and sulfur; R1, R2, or R3 is independently selected from C1-C40 alkyl and its substituted derivatives, C3-C20 alicyclic groups and its substituted derivatives, C3-C30 heterocyclic groups and its substituted derivatives, or C5-C30 aromatic groups and its substituted derivatives; the substituents are independently selected from hydrogen, alkyl, cycloalkyl, aryl, fluoroalkyl, hydroxyl, alkoxy, phenoxy, cyano, nitro, amino, acetylamino, ester, acyl, halogen, or carboxyl.

[0065] In the present application, X is selected from a nitrogen-containing aromatic heterocyclic structure or a nitrogen-containing heterocyclic structure in a tertiary amine structure, and X is selected from any one of the following:

[0066] Formula 101, Formula 102, Formula 103, Formula 104, Formula 105, Formula 106, Formula 107, Formula 108, Formula 109, Formula 110, Formula 111, Formula 112, Formula 113, Formula 114, Formula 115, Formula 116, Formula 117, Formula 118;

[0067] Z in Formulae 103-118 is independently selected from any one or more of the following groups:

[0068] a chemical bond, , , , , , , , , , ;

[0069] Rn in formula 115 and formula 116 is independently selected from C1-C40 alkyl and substituted derivatives thereof, C3-C20 alicyclic group and substituted derivatives thereof, C3-C30 heterocyclic group and substituted derivatives thereof, or C5-C30 aromatic group and substituted derivatives thereof.

[0070] In the present application, if Y is selected from tertiary amine structure selected from nitrogen-containing aromatic heterocyclic structure or nitrogen-containing heterocyclic structure, Y is selected from any one of the following:

[0071] Formula 201, Formula 202, Formula 203, Formula 204, Formula 205, Formula 206, Formula 207, Formula 208, Formula 209, Formula 210, Formula 211, Formula 212, Formula 213, Formula 214, Formula 215,

[0072] Formula 216, Formula 217, Formula 218, Formula 219, Formula 220, Formula 221, Formula 222, Formula 223;

[0073] Rn in formula 203, formula 220, formula 221 is independently selected from C1-C40 alkyl and substituted derivatives thereof, C3-C20 alicyclic group and substituted derivatives thereof, C3-C30 heterocyclic group and substituted derivatives thereof, or C5-C30 aromatic group and substituted derivatives thereof;

[0074] Z in formula 204-223 is independently selected from any one or more of the following groups:

[0075] a chemical bond, , , , , , , , 、 、 .

[0076] In the present application, if X is selected from a tri-substituted amine structure in a tertiary amine structure, X is selected from any one of the following:

[0077] Formula 301, Formula 302, Formula 303, Formula 304, or Formula 305;

[0078] In the present application, if Y is selected from a tri-substituted amine structure in a tertiary amine structure, Y is selected from any one of the following:

[0079] Formula 401, Formula 402, Formula 403, Formula 404, Formula 405, Formula 406;

[0080] In Formula 303, Formula 401 to Formula 405, the Rm substituent is independently selected from an alkyl group, a fluoroalkyl group, an aryl group, a substituted aryl group, a carboxyl group, a nitro group, an alkoxy group, an acetyl group, or a hydroxyl group;

[0081] In Formula 301 to Formula 305, Formula 401 to Formula 406, R6 is independently selected from a C1 to C40 alkyl group and its substituted derivative, a C3 to C20 alicyclic group and its substituted derivative, a C3 to C30 heterocyclic group and its substituted derivative, or a C5 to C30 aromatic group and its substituted derivative;

[0082] In Formula 303, Formula 403, Z is independently selected from any one or more of the following groups:

[0083] a chemical bond, , , , , , , , , , ;

[0084] In Formula 406, n is an integer between 2 and 10.

[0085] The present application is preferably a tertiary amine-containing dianhydride monomer and a tertiary amine-containing diamine monomer, from the obtained monomer containing a tertiary amine structure, whether it is a dianhydride monomer, or a diamine monomer, taking into account the various properties of the present application, under the premise of the ease of obtaining, and the cost considerations. Specifically, the tertiary amine-containing dianhydride monomer is selected from any one or more of the following:

[0086] Formula 501, Formula 502, Formula 503, Formula 504, Formula 505, Formula 506, Formula 507, Formula 508.

[0087] The tertiary amine-containing diamine monomer in the present application is preferably selected from any one of the following:

[0088] Formula 601, Formula 602, Formula 603, Formula 604, Formula 605, Formula 606, Formula 607, Formula 608, Formula 609, Formula 610, Formula 611, Formula 612, Formula 613, Formula 614, Formula 615,

[0089] Formula 616, Formula 617, Formula 618, Formula 619,

[0090] Formula 620, Formula 621, Formula 622, Formula 623,

[0091] Formula 624, Formula 625,

[0092] Formula 626, Formula 627,

[0093] Formula 628, Formula 629,

[0094] Formula 630, Formula 631,

[0095] Formula 632, Formula 633,

[0096] Formula 634, Formula 635,

[0097] Formula 636, Formula 637,

[0098] Formula 638, Formula 639, Formula 640.

[0099] The polyimide resin in the present application is obtained by polycondensation of a dianhydride containing X structure and a diamine containing Y structure.

[0100] The mole amount of the tertiary amine-containing monomer is not less than 60% in the total monomer mole amount of the dianhydride and the diamine.

[0101] In the embodiments of the present application, the dianhydride containing X structure is selected from Formula 501, (N,N'-(pyridine-3,5-diyl)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide) (PDDC)); Formula 502, N,N'-(1H-pyrrole-3,4-diyl)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide) (HPDDC); Formula 503, 5,5'-(1,3,4-oxadiazole-2,5-diyl)bis(isobenzofuran-1,3-dione) (ODID); Formula 504, (2-(1,3-dioxo-1,3-dihydroisobenzofuran-5-yl)isobenzofuran[5,6-d]oxazole-5,7-dione (DDIOD); Formula 505, 2-(1,3-dioxo-1,3-dihydroisobenzofuran-5-yl)-1H-isobenzofuran[5,6-d]imidazole-5,7-dione (DDHID); Formula 506, (5,5'-(piperazine-1,4-diyl)bis(isobenzofuran-1,3-dione) (PDID); Formula 507, 5,5'-(phenylazyl)bis(isobenzofuran-1,3-dione) (PBI); or Formula 508, 5,5'-(1,3-phenylenebis(phenylazyl))bis(isobenzofuran-1,3-dione) (PPBID). The diamine containing Y structure is selected from Formula 602, 2,5-bis(4-aminophenyl)pyridine (PRD); Formula 604, 2,5-bis(4-aminophenyl)pyrimidine (PRM); Formula 608, 4-amino-N-(6-aminopyridin-3-yl)benzamide (AAB); Formula 609, 6-aminopyridin-3-yl 4-aminobenzoate (AYA); Formula 616, N,N'-(pyridine-2,5-diyl)bis(4-aminobenzamide) (PDBA); Formula 624, 2-(4-aminophenyl)-1H-benzo[d]imidazol-6-amine (ABIA); Formula 628, 4-amino-N-(6-aminobenzo[d]oxazol-2-yl)benzamide (AAOB); or Formula 634, N1-(3-aminophenyl)-N1-phenylbenzene-1,3-diamine (APD).

[0102] From the aspects of water solubility after protonation, heat resistance, and photosensitive properties, the polyimide resin of the present application can also have a dianhydride monomer or a diamine monomer that does not contain a tertiary amine.

[0103] Specifically, the tertiary amine-free dianhydride can be exemplified by diphenyl ether-3,3'4,4'-tetracarboxylic dianhydride, benzophenone-3,3'4,4'-tetracarboxylic dianhydride, biphenyl-3,3'4,4'-tetracarboxylic dianhydride, diphenyl sulfone-3,3'4,4'-tetracarboxylic dianhydride, 2,2-bis(3,4-o-phthalic anhydride)propane, diphenyl methane-3',3''4',4''-tetracarboxylic dianhydride, 1,4-diphenoxybenzene-3,3'4,4'-tetracarboxylic dianhydride, 2,2-bis(3,4-o-phthalic anhydride)-1,1,1,3,3,3-hexafluoropropane, and the like. In addition, they can be used alone or in combination with two or more. In a specific embodiment, the tertiary amine-free dianhydride is selected from diphenyl ether-3,3'4,4'-tetracarboxylic dianhydride, benzophenone-3,3'4,4'-tetracarboxylic dianhydride, biphenyl-3,3'4,4'-tetracarboxylic dianhydride, and diphenyl sulfone-3,3'4,4'-tetracarboxylic dianhydride.

[0104] The tertiary amine-free diamine monomer can be exemplified by one or more of 4,4-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 4,4'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminodiphenyl methane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, bis(4-4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, 4,4-bis(4-aminophenoxy)biphenyl, 4,4-bis(3-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)ether, bis(4-(3-aminophenoxy)phenyl)ether, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane, 1,4-bis(3-aminopropyl dimethylsilyl)benzene, and 9,9-bis(4-aminophenyl)fluorene.

[0105] The preparation process of the polyimide described in the present application includes two steps, first, polycondensation to synthesize a polyamide acid intermediate, and then imidization to synthesize a polyimide. The specific reaction route is shown in the following formula: Figure 1

[0106] The present application provides a preparation method of the photosensitive polyimide described in the above technical solution, which comprises the following steps:

[0107] The monomer tetracarboxylic dianhydride, the monomer diamine, and the solvent are mixed to obtain a polyamide acid through polycondensation reaction;​

[0108] The polyamic acid is imidized to obtain a photosensitive polyimide.

[0109] In the present application, the temperature of the polycondensation reaction is <20℃; the time of the polycondensation reaction is 4-24h, and specifically can be 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h or 24h.

[0110] In the present application, the polycondensation reaction is carried out in a solvent, which is a common solvent for polyimide polymerization, and can dissolve acid dianhydride, diamine and the like as raw material monomers; the solvent is preferably selected from amides, cyclic esters, alcohol ethers, halogenated hydrocarbons and the like, and more preferably selected from one or more of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, 3-dimethyl-2-imidazolidinone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, 3-methyl-2-oxazolidinone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-hexalactone, ε-hexalactone, α-methyl-γ-butyrolactone, ketones such as acetone, methyl ethyl ketone, phenyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, m-cresol, p-cresol, dichloromethane, 1,2-dichloroethane, dimethyl sulfoxide and tetramethyl urea.

[0111] In the present application, the imidization reaction can be selected from one of chemical imidization and thermal imidization.

[0112] In the present application, the method of thermal imidization comprises: adding a second solvent that can be azeotroped with water into the reaction system after the polycondensation reaction is completed, heating the reaction system, and distilling the second solvent and water until the theoretical amount of water is distilled, so as to convert the polyamic acid into polyimide.

[0113] In the present application, the second solvent is an organic solvent that can be azeotroped with water, and is preferably selected from one or more of benzene, toluene, xylene, cyclohexanone, methyl acetate, ethyl acetate, chloroform, carbon tetrachloride, diethylene glycol dimethyl ether, chlorobenzene, o-dichlorobenzene, cyclohexane, n-propanol, isobutyl alcohol, isoamyl alcohol, n-pentanol, isopropyl alcohol, chloroethanol and diethyl ether.

[0114] In the present invention, the method of chemical imidization is to convert polyamic acid into polyimide by using a dehydrating agent. The dehydrating agent in the present invention refers to a compound that can react with water, and the process of chemical imidization can be carried out by forming a solvent of the dehydrating agent in an inert solvent to perform chemical imidization. The dehydrating agent is selected from acid anhydride, acyl chloride, phosphorus halide or carbimide, and more preferably one or more of acetic anhydride, trifluoroacetic anhydride, acetyl chloride, phosphorus trichloride and dicyclohexyl carbimide. The molar amount of the dehydrating agent in the present invention is 1-10 times the amount of carboxyl group of the polyamic acid.

[0115] As the selection of the highest molecular weight of the polycondensation polymer formed in the present invention, the molar ratio of the dianhydride and the diamine is preferably close to 1:1; specifically, the molar ratio of the dianhydride:diamine in the present invention is 100:(94-106).

[0116] The polymeric degree value n of the polyimide obtained by the polymerization reaction in the present invention is an integer of 2-150. From the viewpoint of obtaining the photosensitive properties and mechanical properties of the photosensitive polyimide composition, the polymeric degree n is preferably 5-100, and the weight average molecular weight is 0.5×10 4 -10×10 4 ; from the viewpoint of good dispersibility in the aqueous developing solution and good pattern resolution performance, the weight average molecular weight is (1-5)×10 4 .

[0117] After the reaction of forming polyimide in the present invention is completed, the reaction solution system can be directly used to prepare a photosensitive polyimide photoresist. The reaction system can also be precipitated to obtain polyimide resin, and then a certain purification process is carried out to prepare a photosensitive polyimide photoresist.

[0118] In the process of precipitating polyimide resin in the present invention, it is necessary to remove the by-products such as dehydrating condensing agent coexisting in the reaction solution. Specifically, a poor solvent is added to the obtained system to make the polymer precipitate, and the target polyimide can be separated. The poor solvent in the present invention can be a large amount of water, methanol, ethanol, isopropanol, or a combination thereof. The polyimide resin can also be repeatedly subjected to redissolution, reprecipitation and other operations, thereby purifying the polymer and vacuum drying. In order to improve the degree of purification, the solution of the polymer can be passed through a column filled with anion exchange resin or cation exchange resin or both of them swelled by a suitable organic solvent to remove ionic impurities.

[0119] The present invention provides a photoresist, which comprises 100 parts of the photosensitive polyimide described in the above technical solution, 50-200 parts of an acidic compound, 2-50 parts of a photosensitive auxiliary agent, 100-300 parts of a solvent, 0.1-5 parts of a leveling agent and 0.1-10 parts of an adhesion promoter.

[0120] The photoresist in the present application is a positive photosensitive polyimide composition.

[0121] The photoresist provided by the present application comprises 100 parts of the photosensitive polyimide described in the above technical solution.

[0122] The photoresist provided by the present application comprises 50-200 parts of an acidic compound, specifically 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts or 200 parts. The acidic compound in the present application is a proton acidic compound that can protonate the tertiary amine in the polyimide to form a quaternary ammonium salt. This protonated quaternary ammonium salt can be dissolved in neutral water, and neutral water development can be achieved. Specifically, the protonated polyimide resin can be dissolved in neutral water.

[0123] The acidic compound in the present application includes inorganic acids and organic acids; the organic acid can be a carboxylic acid or a sulfonic acid, which can be an aliphatic carboxylic acid, an aromatic carboxylic acid, an aliphatic sulfonic acid or an aromatic sulfonic acid, and can also be a monobasic acid, a dibasic acid or a polybasic acid. Specifically, the acidic compound is selected from one or more of formic acid, acetic acid, oxalic acid, malonic acid, adipic acid, glycolic acid, trifluoroacetic acid, oleic acid, stearic acid, lactic acid, citric acid, malic acid, tartaric acid, ascorbic acid, benzoic acid, salicylic acid, cinnamic acid, p-hydroxybenzoic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, benzene tricarboxylic acid, hydrochloric acid, sulfuric acid and phosphoric acid. The present application is preferably selected from organic acids from the perspective of the performance of the polyimide film formed.

[0124] The photoresist provided by the present application comprises 2-50 parts of a photosensitive auxiliary agent, specifically 2 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts or 50 parts. The photosensitive auxiliary agent is a photoacid generator or a photoinitiator. The photoacid generator generates acid under light irradiation, increases the solubility of the light irradiated part in an alkaline aqueous solution, and thus a positive concave-convex pattern of the light irradiated part dissolved can be obtained. The photosensitive auxiliary agent is preferably selected from photoacid generators, and can form a positive photosensitive feature. As specific examples of the photoacid generator, diazonium naphthoquinone compounds, oxime sulfonate compounds, sulfonium salts, phosphonium salts, diazoniun salts, iodonium salts, and the like can be mentioned. As the diazonium naphthoquinone compound, oxime sulfonate compound, sulfonium salt, phosphonium salt, diazoniun salt, iodonium salt, and the like. As the diazonium naphthoquinone compound, it can be a compound in which diazonium naphthoquinone sulfonic acid is ester-bonded to a polyhydroxy compound, or a compound in which diazonium naphthoquinone sulfonic acid is sulfonamide-bonded to a polyamino compound, or a compound in which diazonium naphthoquinone sulfonic acid is ester-bonded and / or sulfonamide-bonded to a polyhydroxy polyamino compound, and the like. As the photoacid generator, the acid generated by exposure of the sulfonium salt, phosphonium salt, diazoniun salt, can make the exposed component more stable, and is also a necessary component that can be selected. The diazonium naphthoquinone compound can be a compound in which diazonium naphthoquinone sulfonic acid is ester-bonded to a polyhydroxy compound, or a compound in which diazonium naphthoquinone sulfonic acid is sulfonamide-bonded to a polyamino compound, or a compound in which diazonium naphthoquinone sulfonic acid is ester-bonded and / or sulfonamide-bonded to a polyhydroxy polyamino compound, and the like. As the photoacid generator, the acid generated by exposure of the sulfonium salt, phosphonium salt, diazoniun salt, can make the exposed component more stable, and is also a necessary component that can be selected.

[0125] The above photoacid generator, as a positive photoresist system, the role of the photoacid generator can be understood as a dissolution rate control agent. As a specific example of the photoacid generator, the diazonium naphthoquinone sulfonate substance preferred in the present application is mixed and added to the resin, which can reduce the dissolution rate of the polyimide resin in an alkaline aqueous solution. After light exposure, the diazonium naphthoquinone sulfonate substance is converted into indene acid, which significantly enhances the dissolution of polyimide in an alkaline aqueous solution, forms a sufficient dissolution rate difference between the exposed area and the non-exposed area, and thus forms a positive photoetching pattern, realizes the goal of water development and photoetching.

[0126] The photoresist provided by the present application comprises 100-300 parts of solvent, specifically 100 parts, 120 parts, 130 parts, 140 parts, 150 parts, 160 parts, 170 parts, 180 parts, 190 parts, 200 parts, 210 parts, 220 parts, 230 parts, 240 parts, 250 parts, 260 parts, 270 parts, 280 parts, 290 parts or 300 parts. The solvent contained in the photoresist of the present application can be obtained from the polyimide obtained by polymerization reaction. From the perspective of improving the purity and reliability of the photosensitive composition, the polyimide resin can also be purified and then a new solvent is added as a solid component. The solvent is preferably selected from one or more of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, butyl acetate, methyl lactate, ethyl lactate, butyl lactate, isopropyl alcohol, butyl alcohol, amyl alcohol, 3-methyl-2-butanol, 3-methyl-3-methoxybutanol, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, diisobutyl ketone, cyclopentanone, diacetone alcohol, toluene and xylene.

[0127] The photoresist provided by the present application comprises 0.1-5 parts of leveling agent, specifically 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts; the leveling agent is added as needed in the present application; the leveling agent is a surfactant, which is not particularly limited as long as it can improve the wettability with the substrate. As the leveling agent, it can be polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane copolymer, fluorocarbon surfactant, acrylic or methacrylic surfactant. Specifically, such as SH series, SD series, ST series of Dow Corning, BYK series of BYK company and the like.

[0128] The photoresist provided by the present application comprises 0.1-10 parts of an adhesion promoter, specifically 0.1 parts, 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts, 9.5 parts or 10 parts. The adhesion promoter is preferably one or more of vinyltrimethoxysilane, vinyltriethoxysilane, epoxycyclohexylethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, a titanium chelating agent and an aluminum chelating agent. By adding the above-mentioned adhesion promoter, the adhesion to substrates such as silicon wafers, ITO, SiO2, silicon nitride and the like can be improved when the resin film is developed and the like.

[0129] The present application provides a polyimide film prepared by the following method:

[0130] The photoresist described in the above technical solution is coated, pre-baked, exposed, developed and heat-cured to obtain a polyimide film.

[0131] The photoresist provided by the present application is a photoresist solution, which can form a patterned topography through coating, pre-baking, exposure, development, heat curing process.

[0132] The photoresist is coated on the substrate, and as a coating method, it is a conventional method of coating a photosensitive resin, which can be coated by spin coating, rod coating, blade coating, screen printing, spraying and the like.

[0133] After coating, pre-baking, as a drying method, methods such as air drying, heating drying based on an oven or a hot plate, vacuum drying and the like can be listed; the present application preferably dries at 50-140℃ for 1-60 minutes.

[0134] After pre-baking, exposure, the present application uses exposure devices such as a contact photolithography machine, a projection exposure machine, a step-by-step exposure machine and the like, with or without a photo mask or a grating having a pattern, to expose the dried resin layer using an ultraviolet light source and the like.

[0135] Due to the consideration of improving light sensitivity, the present application can also perform post-exposure baking (PEB) and / or pre-development baking. As for the range of baking conditions, the temperature is preferably 40-120℃, and the time is preferably 10-240 seconds.

[0136] After exposure, development is performed. Due to the exposure, the photosensitive auxiliary agent in the photoresist promotes the protonated tertiary amine-containing polyimide resin to be dissolved in the developer, and the development process can be used to remove it. As a development method for developing the resin layer after exposure, the development methods of the existing known photoresists, such as the rotary spray method, the immersion method with ultrasonic treatment, etc., can be listed.

[0137] As the developer used in development, the present application can use an aqueous alkali solution, an aqueous alkaline developer, which can be specifically an aqueous sodium carbonate solution, an aqueous sodium bicarbonate solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, an aqueous tetraalkylammonium hydroxide solution, and preferably an aqueous tetramethylammonium hydroxide solution.

[0138] As a feature of the present application, neutral water can be preferably used as a developer. In order to adapt to most of the current application scenarios and better environmental protection requirements.

[0139] After development, thermal curing is performed. The present application volatilizes the components in the photoresist that are not resistant to heat, such as residual solvents, by heating, and then cures the patterned polyimide film. As a method of thermal curing, it can be a method based on a heating plate, a method using an oven, and a method using a temperature setting type oven. The present application can be cured at a temperature lower than 200°C. While other low-temperature curing in the prior art needs to go through a chemical process, specifically, the polyimide precursor is catalyzed to imidize into polyimide in the presence of various catalysts.

[0140] The patterned film layer obtained by low-temperature curing of the photoresist composition can be applied in the display industry or the semiconductor industry as an insulating layer, a passivation layer, or an interlayer dielectric layer, etc.

[0141] In order to further illustrate the present application, the photo-sensitive polyimide provided by the present application, its preparation method, and the photoresist and polyimide film are described in detail below in conjunction with examples, but they cannot be understood as limiting the scope of protection of the present application.

[0142] Example 1

[0143] The polyimide was prepared by chemical imidization at room temperature in N,N-dimethylacetamide (DMAc). The basic steps of the room temperature polymerization were as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.094 mol 2,5-bis(4-aminophenyl)pyridine (PRD) was first dissolved in 50.0 g DMAc, 0.01 mol diphenyl ether-3,3'4,4'-tetracarboxylic dianhydride (ODPA) and 0.09 mol N,N'-(pyridine-3,5-diyl)bis(l,3-dioxo-l,3-dihydroisobenzofuran-5-carboxamide) (PDDC) were added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0144] 2.0 g of the PI resin, 1.0 g of formic acid, 0.04 g of diazonium naphthoquinone sulfonic acid (DNQ), 2.0 g of N-methyl-2-pyrrolidone (NMP), 0.002 g of polyether-modified polydimethylsiloxane, 0.002 g of vinyltrimethoxysilane were stirred and mixed uniformly to obtain a positive photosensitive polyimide composition.

[0145] Example 2

[0146] 2. The polyimide was prepared by chemical imidization at room temperature in NMP. The basic steps of the room temperature polymerization were as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.096 mol 2,5-bis(4-aminophenyl)pyrimidine (PRM) was first dissolved in 50.0 g NMP, 0.02 mol benzophenone-3,3'4,4'-tetracarboxylic dianhydride (BTDA) and 0.08 mol 2-(l,3-dioxo-l,3-dihydroisobenzofuran-5-yl)isobenzofuran[5,6-d]oxazole-5,7-dione (DDIOD) were added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0147] 2.0 g of the PI resin, 1.2 g of acetic acid, 0.1 g of DNQ, 2.4 g of N,N-dimethylformamide (DMF), 0.01 g of polyester-modified polydimethylsiloxane copolymer, 0.01 g of vinyltriethoxysilane were stirred and mixed uniformly to obtain a positive photosensitive polyimide composition.

[0148] Example 3

[0149] The polyimide was prepared by chemical imidization at room temperature in γ-butyrolactone. The basic steps for room temperature polymerization are as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.098 mol 4-amino-N-(6-aminopyridin-3-yl)benzamide (AAB) was first dissolved in 50.0 g γ-butyrolactone, 0.03 mol biphenyl-3,3'4,4'-tetracarboxylic dianhydride (BPDA) and 0.07 mol 5,5'-(piperazin-1,4-diyl)bis(isobenzofuran-1,3-dione) (PDID) were added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0150] Take 2.0 g of PI resin, 1.4 g of oxalic acid, 0.16 g of DNQ, 2.8 g of DMAc, 0.016 g of fluorocarbon surfactant, 0.02 g of epoxy cyclohexyl ethyl trimethoxysilane, and stir to mix uniformly to obtain a positive photosensitive polyimide composition.

[0151] Example 4

[0152] The polyimide was prepared by chemical imidization at room temperature in γ-butyrolactone. The basic steps for room temperature polymerization are as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.098 mol 4-amino-N-(6-aminopyridin-3-yl)benzamide (AAB) was first dissolved in 50.0 g γ-butyrolactone, 0.03 mol biphenyl-3,3'4,4'-tetracarboxylic dianhydride (BPDA) and 0.07 mol 5,5'-(piperazin-1,4-diyl)bis(isobenzofuran-1,3-dione) (PDID) were added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0153] Take 2.0 g of PI resin, 2.0 g of malonic acid, 0.2 g of DNQ, 3.2 g of γ-butyrolactone, 0.02 g of BYK-310, and 0.04 g of 3-epoxypropoxypropyl trimethoxysilane, and stir to mix uniformly to obtain a positive photosensitive polyimide composition.

[0154] Example 5

[0155] The polyimide was prepared by chemical imidization at room temperature in ethylene glycol dimethyl ether. The basic steps of the room temperature polymerization were as follows: nitrogen was bubbled into a reaction vessel at room temperature, 0.01 mol 4,4-diaminodiphenyl ether (ODA) and 0.09 mol N,N'-(pyridine-2,5-diyl)bis(4-aminobenzamide) (PDBA) were first dissolved in 50.0 g ethylene glycol dimethyl ether, 0.1 mol 5,5'-(1,3,4-oxadiazole-2,5-diyl)bis(isobenzofuran-1,3-dione) (ODID) was added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0156] Take 2.0 g of PI resin, 2.4 g of adipic acid, 0.4 g of DNQ, 4.0 g of NMP, 0.04 g of BYK-333, 0.08 g of 3-glycidoxypropyltriethoxysilane, and stir to mix uniformly to obtain a positive photosensitive polyimide composition.

[0157] Example 6

[0158] The polyimide was prepared by chemical imidization at room temperature in diethylene glycol dimethyl ether. The basic steps of the room temperature polymerization were as follows: nitrogen was bubbled into a reaction vessel at room temperature, 0.0204 mol 4,4'-diaminodiphenyl sulfone (DDS) and 0.0816 mol 2-(4-aminophenyl)-1H-benzo[d]imidazol-6-amine (ABIA) were first dissolved in 50.0 g diethylene glycol dimethyl ether, 0.1 mol 2-(1,3-dioxo-1,3-dihydroisobenzofuran-5-yl)-1H- isobenzofuran[5,6-d]imidazol-5,7-dione (DDHID) was added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0159] Take 2.0 g of PI resin, 3.0 g of glycolic acid, 0.6 g of DNQ, 4.4 g of DMAc, 0.06 g of BYK-323, 0.12 g of p-styryltrimethoxysilane, and stir to mix uniformly to obtain a positive photosensitive polyimide composition.

[0160] Example 7

[0161] The polyimide was prepared by chemical imidization at room temperature in m-cresol. The basic steps for room temperature polymerization are as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.0312 mol ODA and 0.0728 mol 4-amino-N-(6-aminobenzo[d]oxazol-2-yl)benzamide (AAOB) were first dissolved in 50.0 g m-cresol, 0.1 mol 5,5'-(phenyl azo)bis(isobenzofuran-l,3-dione) (PBI) was added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue solution was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0162] 2.0 g of the PI resin, 3.4 g of trifluoroacetic acid, 0.8 g of DNQ, 5.2 g of DMF, 0.08 g of polyether-modified polydimethylsiloxane, and 0.16 g of 3-aminopropyltrimethoxysilane were stirred and uniformly mixed to obtain a positive photosensitive polyimide composition.

[0163] Example 8

[0164] The polyimide was prepared by chemical imidization at room temperature in NMP. The basic steps for room temperature polymerization are as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.0424 mol DDS and 0.0636 mol N1-(3-aminophenyl)-N1-phenylbenzene-1,3-diamine (APD) were first dissolved in 50.0 g NMP, 0.1 mol 5,5'-(l,3-phenylenebis(phenylazo))bis(isobenzofuran-l,3-dione) (PPBID) was added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain a polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol triethylamine and 0.4 mol acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue solution was precipitated in water, filtered. The solid was dried in vacuum to obtain a PI resin.

[0165] 2.0 g of the PI resin, 4.0 g of benzoic acid, 1.0 g of DNQ, 6.0 g of γ-butyrolactone, 0.10 g of polyether-modified polydimethylsiloxane, and 0.20 g of 3-aminopropyltriethoxysilane were stirred and uniformly mixed to obtain a positive photosensitive polyimide composition.

[0166] Comparative Example 1

[0167] The polyimide was prepared by chemical imidization at room temperature in N,N-dimethylacetamide (DMAc). The basic steps of the room temperature polymerization were as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.1 mol ODA was first dissolved in 50.0 g DMAc, 0.1 mol of diphenyl ether-3,3'4,4'-tetracarboxylic dianhydride (ODPA) was added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain the polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol of triethylamine and 0.4 mol of acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain the PI resin.

[0168] 2.0 g of PI resin, 1.0 g of formic acid, 0.04 g of DNQ, 2.0 g of NMP, 0.002 g of polyether-modified polydimethylsiloxane, 0.002 g of vinyltrimethoxysilane were stirred and mixed uniformly to obtain a positive photosensitive polyimide composition.

[0169] Comparative Example 2

[0170] The polyimide was prepared by chemical imidization at room temperature in N,N-dimethylacetamide (DMAc). The basic steps of the room temperature polymerization were as follows: nitrogen was bubbled into the reaction vessel at room temperature, 0.094 mol of 2,5-bis(4-aminophenyl)pyridine (PRD) was first dissolved in 50.0 g of DMAc, 0.01 mol of diphenyl ether-3,3'4,4'-tetracarboxylic dianhydride (ODPA) and 0.09 mol of N,N'-(pyridine-3,5-diyl)bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxamide) (PDDC) were added with stirring at room temperature, the reaction temperature was reduced to the range of 20 °C, and the reaction was carried out for 12 h to obtain the polyimide precursor, polyamic acid. Subsequent chemical imidization, a mixed solution of 0.2 mol of triethylamine and 0.4 mol of acetic anhydride was slowly added, and stirring was carried out at room temperature overnight. The glue liquid was precipitated in water, filtered. The solid was dried in vacuum to obtain the PI resin.

[0171] 2.0 g of PI resin, 0.04 g of DNQ, 2.0 g of NMP, 0.002 g of polyether-modified polydimethylsiloxane were stirred and mixed uniformly to obtain a positive photosensitive polyimide composition.

[0172] Performance test

[0173] 1. Performance test of polyimide resin

[0174] The molecular weight and viscosity of the obtained polyimide resin product were analyzed and tested.

[0175] 2. Performance test of photosensitive polyimide composition

[0176] A polyimide photoresist solution can form a patterned topography via a coating, pre-baking, exposure, development, thermal curing process.

[0177] 1) Coating: The polyimide photoresist solution was spin-coated on a silicon substrate.

[0178] 2) Pre-baking: The silicon wafer was dried on a hot plate at 100 °C for 10 minutes.

[0179] 3) Exposure: The dried resin layer was exposed to light using a projection exposure machine using a photomask with a pattern, using an ultraviolet light source, etc. The post-exposure baking (PEB) conditions were a temperature of 100 °C and a time of 120 seconds.

[0180] 4) Development: A 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) was used as a developer, and development was performed using a spin-spray method.

[0181] 5) Thermal curing: An oven was used to perform thermal imidization treatment on the pattern in a stepwise heating manner, i.e., 100 °C for 1 hour and 200 °C for 1 hour, with a heating rate of 2-10 °C per minute.

[0182] Then cooled to room temperature, the pattern was peeled off from the substrate, and the front surface of the film was observed using an ESEM XL-30 field emission environmental scanning electron microscope with a resolution of 10 nm.

[0183] Imidization rate: A 10 µm PSPI film prepared after patterning was tested for infrared spectrum using a Fourier infrared spectrometer, and the ratio of the characteristic peaks of the C-N stretching vibration at 1380 cm -1 and the benzene ring stretching vibration at 1500 cm -1 was taken, and a PSPI treated at 350 °C for 1 h was taken as a 100% imidized sample, and the imidization rate of each PSPI sample was calculated.

[0184] Thermal performance: A 10 µm PSPI film prepared after patterning was tested for thermal gravimetric curve using a TGA / DSC1 / 1100 thermal gravimetric analyzer from Mettler Toledo, Switzerland, under a N2 atmosphere at a heating rate of 10 °C / min.

[0185] Mechanical performance: A 10 µm PSPI film prepared after patterning was tested for tensile strength (σm), tensile modulus (Et), and elongation at break (εb) using an INSTRON-1121 universal testing machine from Instron, at a tensile rate of 5 mm / min.

[0186] The adhesion test experiment with Cu foil: the polyimide photoresist solution was spin-coated on a 2*2 mm 2 Cu foil, after thermal curing, the Cu foil on the PSPI photoresist film was tested using a tensile shear force tester, observed under a microscope, and the force value obtained after the knife was completely pushed was read in real time, and recorded. The area of the Cu foil was converted to obtain the base bonding strength.

[0187] The test results of the photosensitive polyimide resin of each embodiment 1-8 and comparative examples 1-2 are shown in Table 1:

[0188] Table 1

[0189] Molecular weight Mw Viscosity (dL / g) Example 1 32725 0.316 Example 2 35478 0.324 Example 3 37421 0.341 Example 4 39574 0.362 Example 5 42522 0.425 Example 6 45276 0.416 Example 7 42948 0.397 Example 8 44847 0.405 Comparative Example 1 51754 0.446 Comparative Example 2 33524 0.321

[0190] The test results of the photosensitive polyimide composition of each embodiment 1-8 and comparative examples 1-2 are shown in Table 2 and Table 3:

[0191] Table 2

[0192] Resolution (pm) Imidization rate (%) Td5% (°C) Adhesion strength to Cu foil (N / mm) Example 1 2 98.8 487 0.8 Example 2 3 99.4 482 0.8 Example 3 3 99.5 478 0.9 Example 4 4 98.9 475 1.0 Example 5 3 99.3 482 1.1 Example 6 4 98.7 484 1.1 Example 7 4 98.9 472 1.2 Example 8 5 99.6 471 1.2 Comparative Example 1 20 84.5 275 0.5 Comparative Example 2 20 98.6 464 0.3

[0193] Table 3

[0194] Tensile strength (MPa) Elastic modulus (GPa) Elongation at break (%) Example 1 173 3.3 62 Example 2 167 3.2 65 Example 3 166 3.2 70 Example 4 162 3.1 76 Example 5 181 3.4 64 Example 6 175 3.3 68 Example 7 168 3.3 71 Example 8 164 3.2 73 Comparative Example 1 135 2.4 88 Comparative Example 2 172 3.2 63

[0195] From the test results of the above embodiments and comparative examples, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects: by introducing a tertiary amine structure into the polyimide polymer main chain, and adding an acidic compound to the photosensitive polyimide composition, the protonation of the tertiary amine structure in the polyimide makes the formed polyimide photoresist soluble in the aqueous developer, achieving the goal of aqueous development and photolithography. With the increase of the amount of tertiary amine structure, the degree of protonation is higher, and the photolithography resolution is higher, and the photolithography resolution obtained is ≤5 μm. At the same time, the polyimide resin is directly used, instead of its precursor, to achieve low-temperature curing. Moreover, due to the introduction of the tertiary amine structure, the photoresist has excellent heat resistance, and Td5%>450℃ can be achieved. The introduction of the tertiary amine group is also beneficial to the interface adhesion of copper and the inhibition of copper ion migration. After adding an adhesion promoter to the photosensitive polyimide composition, the adhesion strength between the photoresist and the Cu foil can reach >0.7 N / mm. The photosensitive polyimide obtained by the present application also has excellent mechanical properties.

[0196] The above-mentioned is only the preferred embodiment of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A photosensitive polyimide, characterized in that, It has the structure of Formula I: Formula I; X is a residue of the polyimide monomer tetracarboxylic acid dianhydride; Y is a residue of the polyimide monomer diamine; At least one of X and Y contains a tertiary amine structure; The value of n ranges from 2 to 150.

2. The photosensitive polyimide according to claim 1, characterized in that, The tertiary amine structure is selected from nitrogen-containing aromatic heterocyclic structures, nitrogen-containing heterocyclic structures, or trisubstituted amine structures; The nitrogen-containing aromatic heterocyclic structure is selected from pyridine, pyridazine, pyrimidine, pyrazine, triazine, imidazole, oxazole, oxadiazole, thiazole, pyrazole, indole, quinoline, isoquinoline, purine, benzimidazole or benzoxazole; The nitrogen-containing heterocyclic structure is selected from piperidine, piperazine, pyrrolidine, or morpholine; The trisubstituted amine structure has the structure of formula II: Formula II; R1, R2, or R3 is selected from C1 to C40 alkyl or aryl groups.

3. The photosensitive polyimide according to claim 1, characterized in that, R1, R2, or R3 are independently selected from C1-C40 alkyl groups and their derivatives with substituents, C3-C20 alicyclic groups and their derivatives with substituents, C3-C30 heterocyclic groups and their derivatives with substituents, or C5-C30 aromatic groups and their derivatives with substituents. The substituents are independently selected from hydrogen, alkyl, cycloalkyl, aryl, fluoroalkyl, hydroxyl, alkoxy, phenoxy, cyano, nitro, amino, acetamino, ester, acyl, halogen, or carboxyl.

4. The photosensitive polyimide according to claim 2, characterized in that, X is selected from nitrogen-containing aromatic heterocyclic structures or nitrogen-containing heterocyclic structures in tertiary amine structures, and X is selected from any of the following: Formula 101 Formula 102 Formula 103 Formula 104 Formula 105 Formula 106 Formula 107 Formula 108 Formula 109 Formula 110 Formula 111 Formula 112 Formula 113 Formula 114 Formula 115 Formula 116 Formula 117 Formula 118; In formulas 103 to 118, Z is independently selected from any one or more of the following groups: Chemical bonds , , , , , , , , , ; In Equations 115 and 116, R n It is independently selected from C1-C40 alkyl groups and their substituent derivatives, C3-C20 alicyclic groups and their substituent derivatives, C3-C30 heterocyclic groups and their substituent derivatives, or C5-C30 aromatic groups and their substituent derivatives.

5. The photosensitive polyimide according to claim 2, characterized in that, Y is selected from a nitrogen-containing aromatic heterocyclic structure or a nitrogen-containing heterocyclic structure within a tertiary amine structure, and Y is selected from any of the following: Formula 201 Formula 202 Formula 203 Equation 204 Formula 205 Equation 206 Equation 207 Formula 208 Formula 209 Equation 210 Equation 211 Equation 212 Equation 213 Equation 214 Equation 215 Equation 216 Equation 217 Equation 218 Equation 219 Formula 220 Equation 221 Equation 222 Equation 223; In equations 203, 220, and 221, R n The group is independently selected from C1-C40 alkyl groups and their substituents, C3-C20 alicyclic groups and their substituents, C3-C30 heterocyclic groups and their substituents, or C5-C30 aromatic groups and their substituents. In formulas 204 to 223, Z is independently selected from any one or more of the following groups: Chemical bonds , , , , , , , , , .

6. The photosensitive polyimide according to claim 2, characterized in that, X is selected from a trisubstituted amine structure within a tertiary amine structure, and X is selected from any of the following: Formula 301 Formula 302 Formula 303 Formula 304 or Formula 305; Y is selected from a trisubstituted amine structure within a tertiary amine structure, and Y is selected from any of the following: Formula 401 Formula 402 Formula 403 Formula 404 Formula 405 Formula 406; In Equations 303, 401 to 405, R m The substituents are independently selected from alkyl, fluoroalkyl, aryl, substituted aryl, carboxyl, nitro, alkoxy, acetyl, or hydroxyl groups; In Formulas 301 to 305 and Formulas 401 to 406, R6 is independently selected from C1 to C40 alkyl groups and their derivatives with substituents, C3 to C20 alicyclic groups and their derivatives with substituents, C3 to C30 heterocyclic groups and their derivatives with substituents, or C5 to C30 aromatic groups and their derivatives with substituents.

7. A method for preparing the photosensitive polyimide according to any one of claims 1 to 6, comprising the following steps: The monomer tetracarboxylic acid dianhydride, the monomer diamine, and the solvent are mixed and subjected to a polycondensation reaction to obtain polyamic acid; The polyamic acid was imidized to obtain a photosensitive polyimide.

8. The preparation method according to claim 7, characterized in that, The polycondensation reaction temperature is <20℃; the polycondensation reaction time is 4~24h. The amidation reaction is either a thermal iminoization reaction or a chemical iminoization reaction; The thermal imidization reaction uses a second solvent that azeotropically reacts with water. The chemical imidization reaction uses a dehydrating agent.

9. A photoresist, comprising, by weight, 100 parts of photosensitive polyimide as described in any one of claims 1 to 6, 50 to 200 parts of an acidic compound, 2 to 50 parts of a photosensitive additive, 100 to 300 parts of a solvent, 0.1 to 5 parts of a leveling agent, and 0.1 to 10 parts of an adhesion promoter.

10. A polyimide film, prepared by the following method: The photoresist described in claim 9 is coated, pre-baked, exposed, developed, and thermally cured to obtain a polyimide film.

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