Composition for forming a polyimide coating

Abstract

A composition and method effective for forming a polyimide film with reduced dissipation rate and / or thermal expansion coefficient. The composition comprises a polyimide precursor and a selected crosslinking agent. The crosslinking agent is of the formula: (R')2-C=C(R')-L-[C(R')=C(R')2] n (In the formula, R' is independently H or an alkyl group of 1 to 3 carbon atoms in each instance, L is a hydrocarbon group of 2 to 10 carbon atoms, and L is the -C(=O)-(O) m L may have the formula -R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms, and m is 0 or 1), or L may have the formula -R'''-O-R'''- (wherein R''' is an alkylene group of 1 to 6 carbon atoms independently in each occurrence, and n is 1, 2, or 3).

Description

[Technical Field] 【0001】 (Cross-reference of related applications) This application claims the benefits of U.S. Provisional Application No. 63 / 500,658, filed on 8 May 2023, the disclosures thereof being incorporated herein by reference in their entirety. 【0002】 (Field of Invention) The field of the present invention relates to photosensitive compositions useful for forming polyimide films. [Background technology] 【0003】 Polyimide resins are useful in the electronics industry. For example, they can be used as insulating and / or passivation layers in the manufacture of integrated circuits. In these applications, the polyimide is located adjacent to other layers, such as deposited metals. 【0004】 Dissipation factor (DF) is a dimensionless (i.e., unitless) measure of the electrical properties of plastics and other electrical insulating materials. It is defined as the reciprocal of the ratio between the capacitive reactance of the insulating material and its resistance (equivalent series resistance, ESR) at a given frequency. In other words, it is defined as the ratio between the dielectric constant and conductivity of the electrical insulating material. It measures the electrical energy (power dissipation) that is absorbed and lost when current is applied to the insulating material. Dissipation factor indicates the inefficiency of a material in retaining energy or behaving as an insulating material. The lower the dissipation factor, the more efficient the insulating system. Polyimides generally have relatively low dissipation factors (e.g., 0.01-0.02), but polyimides with even lower dissipation factors are desirable. 【0005】 At the same time, in certain electronic applications, the polyimide layer is adjacent to other layers and features, such as deposited metals and metal vias. Compatibility between the polyimide and these materials is important. One aspect of compatibility is how similar the materials are in terms of their coefficient of thermal expansion (CTE). If the CTEs differ significantly, the device will experience additional mechanical stress when subjected to temperature changes (e.g., when heating occurs during use). The linear thermal expansion coefficient of metals is generally in the range of 3 to 20 parts per million (ppm) / Kelvin (or Celsius temperature). For example, copper has a linear thermal expansion coefficient (CLTE) of 17 parts per million (ppm) / Kelvin at 20°C and a volumetric expansion coefficient of 51 ppm / Kelvin at 20°C. In contrast, polymers generally have higher CTEs. 【0006】 It is desirable to have a coating composition for producing a polyimide film that has both a low dissipation rate and a low CTE. [Overview of the Initiative] 【0007】 This specification provides a method for reducing the dissipation rate and coefficient of thermal expansion of a film formed from a selected polyimide precursor, wherein the polyimide precursor contains an ethylenically unsaturated polyimide precursor available for free radical reactions, and the polyimide precursor is given the formula: (R')2-C=C(R')-L-[C(R')=C(R')2] n (In the formula, R' is independently H or an alkyl group of 1 to 3 carbon atoms in each occurrence, L is a hydrocarbon group of 2 to 10 carbon atoms, preferably 2 to 8, more preferably 2 to 7, and even more preferably 2 to 6 carbon atoms, and L is a hydrocarbon group of the formula -C(=O)-(O) mA method is disclosed comprising: forming a coating composition with a crosslinking agent having the formula -R'' (wherein R'' is 1 to 6, preferably 1 to 3, more preferably 1 or 2, alkylene groups of carbon atoms, and m is 0 or 1) or L having the formula -R'''-O-R'''- (wherein R''' is independently 1 to 6, preferably 1 to 3, more preferably 1 or 2, alkylene groups of carbon atoms in each occurrence, and n is 1, 2, or 3), a photoinitiator, and a solvent; applying the coating composition to a substrate; drying to remove the solvent to form a solid coating; exposing the solid coating to radiation of an activation wavelength to react the crosslinking agent with the ethylenically unsaturated polyimide precursor; and curing to form a film. 【0008】 Furthermore, this specification discloses a coating composition comprising a polyimide precursor, a photoinitiator, a crosslinking agent, and a solvent, wherein the polyimide precursor contains an ethylenically unsaturated compound available for free radical reactions, and the crosslinking agent is of the formula (R')2-C=C(R')-LC(R')=C(R')2] n (wherein R' is independently an alkyl group of H or 1 to 3 carbon atoms in each occurrence, L is a linear or branched aliphatic hydrocarbon group of 2 to 7 carbon atoms, L has the formula -C(=O)-O-R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms), or L has the formula -R''-O-R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms), and n is 1, 2, or 3). 【0009】 Furthermore, this specification discloses a coating composition comprising a polyimide precursor, a photoinitiator, a crosslinking agent, and a solvent, wherein the polyimide precursor contains ethylenically unsaturated material available for free radical reactions, and the crosslinking agent comprises a linking group L having five or fewer atoms (excluding pendant atoms and pendant groups) covalently bonded between two ethylenically unsaturated groups, and a polyimide film formed by a process comprising coating the composition onto a substrate, drying to remove the solvent and form a dry coating, and exposing the dry coating to radiation of an activation wavelength to react the crosslinking agent with the polyimide precursor, has a dissipation rate of 0.0074 or less, preferably less than 0.007. 【0010】 Furthermore, this specification discloses a coating composition comprising a polyimide precursor, a photoinitiator, a crosslinking agent, and a solvent, wherein the polyimide precursor contains an ethylenically unsaturated compound available for free radical reactions, and the crosslinking agent is of the formula: (R')2-C=C(R')-L-[C(R')=C(R')2] n A polyimide film formed by a process comprising applying a composition to a substrate, drying it to remove the solvent to form a dry coating, and exposing the dry coating to radiation of an activation wavelength to react the crosslinking agent with the polyimide precursor, having a dissipation rate of less than 0.0074, preferably less than 0.007. 【0011】 Also disclosed are articles prepared by applying such a coating composition to a substrate, drying it to form a dry coating, exposing the coating to radiation of an activation wavelength, and curing it to form a polyimide film, wherein the polyimide film is characterized by a dissipation rate of 0.0074 or less, preferably less than 0.007, as determined by the Kent method, and a linear thermal expansion coefficient of less than 52 ppm / Kelvin, as determined by thermomechanical analysis. [Modes for carrying out the invention] 【0012】 The coating compositions disclosed herein, comprising a polyimide precursor having a specific crosslinking agent, provide a polyimide with a remarkably good balance between a low dissipation rate and a low coefficient of thermal expansion. 【0013】 Polyimide precursor The polyimide precursor contains a polyamic acid having a functional group that promotes photoreactions. For example, the polyamic acid may be a polyamic acid ester containing ethylenically unsaturated compounds. 【0014】 Polyamic acids may be prepared from one or more dianhydride compounds and one or more diamine compounds. Photoreactivity can be provided or enhanced by derivatization of polyamic acids having ethylenically unsaturated properties. 【0015】 The dianhydride compound can include, for example, 4,4'-bisphenol A diphthalic anhydride (4,4'-bisphenol A diphthalic anhydride, BPADA), hydroquinone diphthalic anhydride (hydroquinone diphthalic anhydride, HQDA), oxydiphthalic anhydride (oxydiphthalic anydride, ODPA), biphenyltetracarboxylic dianhydride (biphenyltetracarboxylic dianhydride, BPDA), bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, BCODA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (4,4'-(Hexafluoroisopropylidene)diphthalic anhydride, 6FDA), cyclobutanetetracarboxylic dianhydride (cyclobutanetetracarboxylic dianhydride, CBDA), p-phenylene bis(trimellitate)dianhydride (p-Phenylene bis(trimellitate)dianhydride, TAHQ), 3-(carboxymethyl)-1,2,4-cyclopentanetricarboxylic acid 1,4:2,3-dianhydride (3-(Carboxymethyl)-1,2,4-cyclopentanetricarboxylic Acid 1,4:2,3-dianhydride, TCA-AH), or a combination of two or more thereof (for example, a combination of two of them or a combination of three of them). As a more specific example, the dianhydride can include, consist essentially of, or consist of ODPA, BPDA, or a combination thereof. 【0016】 Diamine compounds include, for example, oxydianiline (ODA), 4-dimethylaminopyridine (DMAP), 4,4'-(1,4-Phenylenediisopropylidene)bisaniline (Bis-P), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and isophorone diamine. This may include diamine (IPDA), 4-aminophenylsulfone (DDS), 2,2'-bis(trifluoromethyl)benzidine (TFMB), 4,4'-methylenebis(2-methylcyclohexyl-amine) (DMDC), 4,4'-(1,3-phenyldiisopropylidene)bisaniline (Bis-M), 1,3'-bis(3-aminophenoxy)benzene (APB-133), p-phenylene diamine (PPD), or m-xylenediamine, or two or more combinations thereof (for example, two combinations or three combinations thereof). 【0017】 As a more specific example, polyimides can be formed from ODPA and BAPP, or ODPA and Bis-P, or ODPA and DMAP, or BPDA and TFMB, or ODPA with both BAPP and DMAP, or both ODPA and BPDA with DMAP, or both ODPA and BPDA with both DMAP and PPD. 【0018】 To form a derivatized polyamic acid, an ethylenically unsaturated compound such as an acrylate or an ethylenically unsaturated alcohol can be reacted with a dianhydride or a polyimide precursor formed from a dianhydride and a diamine. Examples of acrylates include hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), and hydroxybutyl methacrylate (HBMA). Examples of ethylenically unsaturated alcohols include those having 3 to 8 or 4 to 6 carbon atoms, such as allyl alcohol or 4-penten-1-ol. For example, an acrylic such as HEMA can be reacted with a dianhydride to form a partially esterified compound. 【0019】 U.S. Patent No. 4,551,522 discloses an example of how such a derivatized polyamic acid can be formed. 【0020】 The polyimide precursor can include, for example, a repeating unit represented by formula (1) 【0021】 【Chemical formula】 and can contain a repeating unit represented by formula (1) In formula (1), X1 is a tetravalent aromatic group or alicyclic group, preferably aromatic, the -COOR1 group and the -CONH- group are ortho to each other, the -COOR2 group and the -CO- group are ortho to each other, Y1 is a divalent aromatic group or alicyclic group, preferably aromatic, R1 and R2 are independently a hydrogen atom, a group represented by the following formula (2) or the following formula (3), or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and at least one of R1 and R2 is a group represented by formula (2) or formula (3). 【0022】 【Chemical formula】 [ka] In formulas (2) and (3), R3 to R5 are independently a hydrogen atom or an aliphatic hydrocarbon group having 1 to 3 carbon atoms, and m is an integer from 1 to 10, preferably an integer from 2 to 5, and more preferably 2 or 3. 【0023】 The tetravalent aromatic group X1 in formula (1) may be a tetravalent aromatic hydrocarbon group or a tetravalent aromatic heterocyclic group. A tetravalent aromatic hydrocarbon group is preferred. Examples of the tetravalent aromatic hydrocarbon group X1 in formula (1) include, but are not limited to, the group represented by formula (4) below. 【0024】 [ka] In formula (4), X and Y independently represent a divalent group or single bond that is not conjugated to the benzene ring to which they are bonded, and Z is an ether group (-O-) or a sulfide group (-S-) (-O- is preferred). In formula (6), the divalent groups of X and Y that are not conjugated to the benzene ring to which they are bonded are preferably -O-, -S-, a methylene group, a bis(trifluoromethyl)methylene group, or a difluoromethylene group, and more preferably -O-. 【0025】 The divalent aromatic group Y1 in formula (1) may be a divalent aromatic hydrocarbon group or a divalent aromatic heterocyclic group. A divalent aromatic hydrocarbon group is preferred. Examples of the divalent aromatic hydrocarbon group Y1 in formula (1) include, but are not limited to, the group represented by formula (5) below. 【0026】 [ka] In formula (5), R 12 ~R 19 These are, independently, a hydrogen atom, a monovalent aliphatic hydrocarbon group, or a monovalent organic group having a halogen atom. 【0027】 R in formula (5) 12 ~R 19 Examples of the monovalent aliphatic hydrocarbon group (preferably having 1 to 10 carbon atoms, more preferably having 1 to 6 carbon atoms) include a methyl group and the like. For example, R 12 and R 15 ~R 19 may be a hydrogen atom, and R 13 and R 14 may be a monovalent aliphatic hydrocarbon group. R in formula (5) 12 ~R 19 As the monovalent organic group having a halogen atom (preferably a fluorine atom) of R~R, a monovalent aliphatic hydrocarbon group having a halogen atom (preferably having 1 to 10 carbon atoms, more preferably having 1 to 6 carbon atoms) is preferred, and a trifluoromethyl group and the like are mentioned. 【0028】 Examples of the aliphatic hydrocarbon group having 1 to 4 carbon atoms (preferably 1 or 2 carbon atoms) of R1 and R2 in formula (1) include a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, an n-butyl group and the like. 【0029】 At least one of R1 and R2 in formula (1) is a group represented by formula (2) or formula (3). Examples of the aliphatic hydrocarbon group having 1 to 3 carbon atoms (preferably 1 or 2 carbon atoms) in R3~R5 of formula (2) include a methyl group, an ethyl group, an n-propyl group, a 2-propyl group and the like. A methyl group is preferred. 【0030】 The polyimide precursor having a structural unit represented by formula (1) can be obtained, for example, by reacting a tetracarboxylic dianhydride represented by the following formula (6) and a diamino compound represented by the following formula (7) in an organic solvent such as N-methyl-2-pyrrolidone to obtain a polyamic acid, adding a compound represented by the following formula (8), and reacting in an organic solvent to introduce a partial ester group. 【0031】 The tetracarboxylic dianhydride represented by formula (6) and the diamino compound represented by formula (7) may be used individually or in combination of two or more. 【0032】 [ka] In equation (6), X1 is the base corresponding to X1 in equation (1). [ka] In equation (7), Y1 is as defined in equation (1). 【0033】 [ka] In equation (8), R is the group represented by equation (2). 【0034】 The polyimide precursor may contain additional repeating units other than the repeating unit represented by formula (1), for example, they may form copolymers. An example of a repeating unit other than the structural unit represented by formula (1) is the structural unit represented by formula (9) below. 【0035】 [ka] In formula (9), X2 is a tetravalent aromatic group or alicyclic group, and -COOR 51 The -CONH- group and the -COOR group are in the ortho position relative to each other. 52 The group and the -CO- group are in the ortho position relative to each other. Y2 is a divalent aromatic group or alicyclic group, and R 51 and R 52 R is an aliphatic hydrocarbon group that independently has a hydrogen atom or 1 to 4 carbon atoms. Examples of the tetravalent aromatic group X2 in formula (9) are the same as the tetravalent aromatic group X1 in formula (1). Examples of the divalent aromatic group Y2 in formula (9) are the same as the divalent aromatic group Y1 in formula (1). 51 and R 52Examples of aliphatic hydrocarbon groups having 1 to 4 carbon atoms include the same aliphatic hydrocarbon groups having 1 to 4 carbon atoms as R1 and R2. Structural units other than the structural unit represented by formula (1) may be used individually or in combination of two or more. 【0036】 The content of repeating units other than the structural unit represented by formula (1) is 0-99, 0-70, 30-70, or 40-60 mol%, based on the total repeating units of the polyimide precursor. 【0037】 In polyimide, the ratio of carboxyl groups esterified with the group represented by formula (2) to total carboxyl groups and total carboxyesters is preferably 50 mol% or more, more preferably 60 to 100 mol%, and even more preferably 70 to 90 mol%. 【0038】 The molecular weight of the polyimide precursor is not particularly limited, but the number-average molecular weight is preferably 10,000 to 200,000. The number-average molecular weight can be measured, for example, by gel permeation chromatography and can be calculated by conversion using a standard polystyrene calibration curve. 【0039】 As described above, the polyimide precursor may be a blend of two or more polyimide precursor polymers. 【0040】 The polyimide precursor does not have to contain Si atoms. In addition, or alternatively, the polyimide precursor does not have to contain a pendant group of the structure -NHCOCN-X (wherein x is a monovalent photosensitive group). 【0041】 The polyimide precursor may be present in the coating composition in an amount of 20-60 or 30-50 weight percent based on the total weight of the coating composition. The polyimide precursor may be present in the coating composition in an amount of 50-95, 60-90, or 65-87 weight percent based on the total weight of the solids in the coating composition. 【0042】 The coating composition does not necessarily have to contain any resins other than the polyimide precursor. 【0043】 Crosslinking agent The crosslinking agent contains two or more (e.g., two, three, or four) ethylenically unsaturated groups. The inventors have discovered that coating compositions having a particular type of crosslinking agent can remarkably provide polyimide films with remarkably lower dissipation rates and lower coefficients of thermal expansion than other crosslinking agents of the same polyimide precursor. 【0044】 A crosslinking agent effective in providing a combination of low dissipation rate and low thermal expansion coefficient may include a linking group L between two ethylenically unsaturated groups, where L comprises a short chain of atoms covalently bonded between any two ethylenically unsaturated groups and does not include a longer chain of atoms between any two ethylenically unsaturated groups. When determining the chain length, only the atoms in the chain linking the ethylenically unsaturated groups are considered. Pendant atoms (e.g., hydrogen atoms on carbon atoms in the chain) and pendant groups (e.g., pendant methyl groups from carbon atoms in the chain) are not considered. In particular, the crosslinking agents disclosed herein include at least one but no more than five, preferably two to four, and more preferably three to four atoms in the chain of the linking group L. Examples of atoms in the chain include carbon, oxygen, or a combination of carbon and oxygen atoms. 【0045】 For example, the linking group L may be (i) a linear aliphatic hydrocarbon with 2 to 5 carbon atoms, (ii) an alicyclic hydrocarbon with 5 to 7 carbon atoms, or (iii) have the following structures. 【0046】 [ka] (In the formula, R is a divalent hydrocarbon group consisting of 1 to 3 carbon atoms, -O-CH2-, or -O-CH2-CH2-). 【0047】 A crosslinking agent effective in providing a combination of low dissipation rate and low thermal expansion coefficient is given by the formula: (R')2-C=C(R')-L-[C(R')=C(R')2] n (In the formula, R' is independently H or an alkyl group of 1 to 3 carbon atoms in each occurrence, L is a hydrocarbon group of 2 to 10 carbon atoms, preferably 2 to 8, more preferably 2 to 7, and even more preferably 2 to 6 carbon atoms, and L is a hydrocarbon group of the formula -C(=O)-(O) m L may have the formula -R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms, preferably 1 to 3, more preferably 1 or 2, and m is 0 or 1), or L may have the formula -R'''-O-R'''- (wherein R''' is an alkylene group of 1 to 6 carbon atoms, preferably 1 to 3, more preferably 1 or 2, independently in each occurrence, and n is 1, 2, or 3). L may be a linear or branched aliphatic hydrocarbon group of 2 to 7 carbon atoms, preferably 2 to 6, and L may have the formula -C(=O)-(O) m -R''- (wherein R'' is 1 to 6, preferably 1 to 3, more preferably 1 or 1, most preferably 1 carbon atom alkylene group, and m is 0 or 1) or L is -R'''-O-R'''- (wherein R''' is independently 1 to 6, preferably 1 to 3, more preferably 1 or 2 carbon atom alkylene groups in each occurrence). 【0048】 Preferably, L is not an alkylene glycol or an alkylene glycol derivative. 【0049】 Specific examples of crosslinking agents that can be used with polyimide precursors to provide polyimides with low dissipation rates and low CTEs include allyl methacrylate and 1,2,4-trivinylcyclohexane. 【0050】 The crosslinking agent can be present in the coating composition in amounts of 1 to 50, 5 to 40, 10 to 35, or 15 to 30 parts by weight per 100 parts by weight of the polyimide precursor. 【0051】 The composition does not necessarily have to contain a thermal crosslinking agent such as 1,3-phenylenebisoxazoline or epoxy resin. 【0052】 solvent The coating composition comprises a solvent in which the polyimide precursor is dispersed, or more preferably, in which the polyimide precursor is dissolved. Examples of such solvents include N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), alcohols such as methanol, acetone, toluene, acetophenone, propylene glycol, alkyl acetates such as ethyl acetate, cyclopentanone, cyclohexanone, γ-butyrolactone, ethyl lactate, propylene glycol monomethyl ether acetate, benzyl acetate, n-butyl acetate, ethoxyethyl propionate, 3-methyl methoxypropionate, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphorylamide, tetramethylene sulfone, diethyl ketone, diisobutyl ketone, methyl amyl ketone, N-dimethylmorpholine, or two or more combinations thereof. Among these, 1-methyl-2-pyrrolidone, γ-butyrolactone, ethyl lactate, propylene glycol monomethyl ether acetate, N,N-dimethylformamide, and N,N-dimethylacetamide are preferred due to their excellent solubility of each component and their suitability for application when forming a photosensitive resin film. 【0053】 As an alternative solvent, a compound represented by the following formula (10) may be used. 【0054】 [ka] In the formula, R 41 ~R 43 These are, independently, alkyl groups having 1 to 10 carbon atoms. 【0055】 R in equation (10) 41 ~R 43Examples of alkyl groups having 1 to 10 (preferably 1 to 3, more preferably 1 or 3) carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, pentyl, hexyl, heptyl, and octyl groups. 【0056】 The amount of solvent can be selected to ensure that the other components dissolve and to adjust the viscosity to a suitable level for coating application. For example, the solvent may be present in an amount of 30-80 or 30-60 weight percent based on the total weight of the composition. As another example, the solvent may be present in an amount of 50-1000 parts by mass per 100 parts by mass of polyimide precursor. 【0057】 Photoinitiator The coating composition may further contain a photoinitiator. Examples of suitable photoinitiators include benzophenone derivatives, e.g., benzophenone, o-benzoylmethyl benzoate, 4-benzoyl-4'-methyldiphenyl ketone, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime), dibenzyl ketone, and fluorenone; acetophenone derivatives, e.g., 2,2'-diethoxyacetophenone, 2-hydroxy-2-methylpropiophenone, and 1-hydroxycyclohexylphenyl ketone; thioxanthone derivatives, e.g., thioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, and diethylthioxanthone; benzyl derivatives, e.g., benzyl, benzyldimethyl ketal, and benzyl-β-methoxyethyl acetal; benzoin derivatives, e.g., benzyl Examples include benzoin and benzoin methyl ether; and oxime esters, such as 1-phenyl-1,2-butanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-methoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-1,2-propanedione-2-(o-benzoyl)oxime, 1,3-diphenylpropanetrione-2-(o-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxypropanetrione-2-(o-benzoyl)oxime, ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-, 1-(O-acetyloxime), and compounds represented by the following compounds. 【0058】 [ka] 【0059】 For example, the photoinitiator may be 1-phenyl-1,2-propanedione-2-(o-ethoxycarboxy)oxime. 【0060】 The photoinitiator can be present in an amount of 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the polyimide precursor. 【0061】 Additional additives The coating composition may further contain additional additives such as inhibitors, sensitizers, adhesion promoters, or corrosion inhibitors. 【0062】 An example of an inhibitor is 2,3-diazabicyclo[3.2.2]nona-2-ene,1,4,4-trimethyl-,2,3-dioxide. 【0063】 Examples of sensitizers include N,N,N',N'-tetraethyl-4,4'-diaminobenzophenone, Michler ketone, benzoin, 2-methylbenzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, 2-t-butylanthraquinone, 1,2-benzo-9,10-anthraquinone, anthraquinone, methylanthraquinone, 4,4'-bis-(diethylamino)benzophenone, acetophenone, benzofenone, thioxanthone, 1,5-acenaphthene, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, diacetylbenzyl, Examples include dimethyl ketal, benzyl diethyl ketal, diphenyl disulfide, anthracene, phenanthrene quinone, riboflavin tetrabutyrate, acridine orange, erythrosine, phenanthrene quinone, 2-isopropylthioxanthone, 2,6-bis(p-diethylaminobenzylidene)-4-methyl-4-azacyclohexanone, 6-bis(p-dimethylaminobenzylidene)-cyclopentanone, 2,6-bis(p-diethylaminobenzylene)-4-phenylcyclohexanone, aminostyryl ketone, 3-ketocoumarin compounds, biscoumarin compounds, N-phenylglycine, N-phenyldiethanolamine, and 3,3',4,4'-tetra(t-butylper)oxycarbonyl)benzophenone. Sensitizers may be used alone or in combination of two or more. If the photosensitive resin composition of this disclosure contains a sensitizer, the amount of sensitizer blended is preferably 0.1 to 1.0 parts by mass, and preferably 0.2 to 0.8 parts by mass, per 100 parts by mass of the polyimide precursor. 【0064】 Examples of adhesion promoters include silane coupling agents, such as N-(triethoxysilylpropyl)γ-aminopropyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, 3-methacryloxypropyldimethoxymethylsilane, 3-methacryloxypropyltrimethoxysilane, dimethoxymethyl-3-piperidinopropylsilane, diethoxy-3-glycidoxypropylmethylsilane, N-(3-diethoxymethylsilylpropyl)succinimide, and N-[3-(triethoxysilyl)propyl]phthalamine. Examples include dihydrochloric acid, benzophenone-3,3'-bis(N-[3-triethoxysilyl]propylamide)-4,4'-dicarboxylate, benzene-1,4-bis(N-[3-triethoxysilyl]propylamide)-2,5-dicarboxylate, 3-(triethoxysilyl)propyl succinic anhydride, N-phenylaminopropyltrimethoxysilane, and alkylsilane-functionalized amine compounds containing N-phenyl-3-aminopropyltrimethoxysilane; or aluminum-based adhesive aids, such as aluminum tris(ethyl acetoacetate), aluminum tris(acetyl acetoacetate), and ethyl acetoacetate aluminum diisopropylate. Among these adhesive aids, it is more preferable to use a silane coupling agent from the viewpoint of adhesive strength. When the photosensitive resin composition contains an adhesive aid, the amount mixed is preferably in the range of 0.5 to 25 parts by mass based on 100 parts by mass of the polyimide precursor. 【0065】 Examples of corrosion inhibitors include azole compounds, such as 1H-triazole, 5-methyl-1H-triazole, 5-ethyl-1H-triazole, 4,5-dimethyl-1H-triazole, 5-phenyl-1H-triazole, 4-t-butyl-5-phenyl-1H-triazole, 5-hydroxyphenyl-1H-triazole, phenyltriazole, p-ethoxyphenyltriazole, 5-phenyl-1-(2-dimethylaminoethyl)triazole, 5-benzyl-1H-triazole, hydroxyphenyltriazole, 1,5-dimethyltriazole, 4,5-diethyl-1H-triazole, 1H-benzotriazole, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, and 2-[2-hydroxy-3,5-bis(a,a-dimethylbenzyl)phenyl Examples include ]-benzotriazole, 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-benzotriazole, 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, hydroxyphenylbenzotriazole, tolyltriazole, 5-methyl-1H-benzotriazole, 4-methyl-1H-benzotriazole, 4-carboxy-1H-benzotriazole, 5-carboxy-1H-benzotriazole, 1H-tetrazol, 5-methyl-1H-tetrazol, 5-phenyl-1H-tetrazol, 5-amino-1H-tetrazol, and 1-methyl-1H-tetrazol. One or more selected from tolyltriazole, 5-methyl-1H-benzotriazole, and 4-methyl-1H-benzotriazole are particularly preferred. These azole compounds may be used individually or as a mixture of two or more of them. If the photosensitive resin composition of this disclosure contains a corrosion inhibitor, the content of the corrosion inhibitor is preferably 0.01 to 10, more preferably 0.5 to 5, and even more preferably 1 to 3 parts by mass per 100 parts by mass of the polyimide precursor. 【0066】 These additional additives may be present in amounts ranging from 0 or 0.15 to less than 5, less than 3, less than 2, or less than 1% by weight, based on the total weight of the coating composition. 【0067】 The coating composition does not need to contain ammonium salts. 【0068】 method The coating compositions disclosed herein can be coated onto a substrate such as a silicon wafer (with or without features such as a metallic layer) and dried. The coating composition can then be exposed to radiation of an activation wavelength to crosslink the polyimide precursor. Exposure to radiation may be done through a mask or by laser addressing of the coating. The unexposed areas can then be removed with a solvent. The remaining x-bonds are cured to form polyimide. 【0069】 Polyimide The resulting polyimide film can have a thickness of, for example, 3 to 15 microns. 【0070】 The resulting polyimide film may have a dissipation rate of 0.0074 or less, or less than 0.0074, preferably less than 0.007. The dissipation rate may be at least 0.002. The dissipation rate can be measured by a vector network analyzer such as the Rohde & Schwarz ZNB40 VNA at 18 Herz. The dispersion coefficient can be determined by the Kent method (see, for example, Nondestructive Permittivity Measurement of Substrates, Gordon Kent, IEEE Transactions of Instrumentation and Measurement, Vol. 45, No. 1, February 1996). 【0071】 The resulting polyimide film may have a linear thermal expansion coefficient (CTE) of less than 52, less than 51.5, less than 51, or 50.5 parts per million / Kelvin when measured by thermomechanical analysis using a thermomechanical analyzer such as the Hitachi™ TMA7100 at a temperature of 70 to 120°C. The CTE of the polyimide film may be at least 15, at least 20, greater than 30, greater than 31, greater than 32, greater than 33, greater than 34, or greater than 35 parts per million / Kelvin. [Examples] 【0072】 A. Preparation of polyimide precursors: Photosensitive polyamic acid ester precursors can be prepared by reacting a dianhydride, a diamine, and an ethylenically unsaturated group with a crosslinking agent using the method described herein or the method described in U.S. Patent No. 4,551,522. 【0073】 B. Evaluation of lithography performance: A photosensitive negative PI composition is coated onto a 4-inch silicon wafer to a thickness of 10 μm by a spin coater after curing. The coated wafer is soft-baked on a hot plate at 90°C for 2 minutes, followed by 110°C for 2 minutes. The coated film is exposed through a mask using an AOI exposure unit and developed with cyclopentanone. The wafer is then cured at a given temperature to form a polyimide. The resolution of the resulting pattern is measured using an optical microscope. 【0074】 C. Measurement of the dissipation rate Df: A photosensitive negative PI composition is coated onto a 6-inch silicon wafer to a thickness of 10 μm by a spin coater after curing. The coated wafer is soft-baked on a hot plate at 90°C for 2 minutes, followed by 110°C for 2 minutes. It is exposed to 400 mJ / cm2 of UV light. The wafer is then cured at 280°C for 2 hours under N2 flow. The polyimide film is removed from the wafer. Df is measured at 18 GHz using a Rohde & Schwarz ZNB40 VNA (vector network analyzer) with the cured film. 【0075】 Measurement of D.CTE (Coefficient of Thermal Expansion) Linear CTE was determined by TMA using a Hitachi TMA7100. Reported data ranged from 70°C to 120°C. 【0076】 Examples 1-17 Preparation of photosensitive coating composition The photosensitive composition is prepared by mixing a polyimide precursor, a crosslinking agent, a photoinitiator, and other additives in the solvents listed in Table 1. 【0077】 [Table 1] 【0078】 The coating formulations were prepared as described above from a polyimide precursor, which is a polyimide partially esterified with acrylate, and the crosslinking agents listed in Table 2. These samples were tested for dissipation rate (Df) and CTE (parts per million / Kelvin) as described above. The results are shown in Table 2. 【0079】 [Table 2-1] 【0080】 [Table 2-2] 【0081】 Examples 4 and 5 show a better combination of lower dissipation and lower CTE than the comparative examples. 【0082】 Example 18 Various polyimide precursors functionalized with hydroxyethyl methacrylate were tested in combination with the crosslinking agents AMA, TVCH, TEGDMA, and PEGDA. Coating compositions were prepared substantially as shown in Table 1, except for the use of different oxime photoinitiators. 【0083】 Polyimide precursor A is based on ODPA and BAPP, and polyimide precursor B is based on ODPA and Bis-P. Polyimide precursor C is based on BPDA and TFMB. Polyimide D is the reaction product of two dianhydrides reacted with two diamines. 【0084】 The results shown in Table 3 demonstrate that AMA and TVCH provide lower dissipation rates with each polyimide precursor. 【0085】 [Table 3] 【0086】 Example 19 As shown in Table 4, various functional groups were tested on the polyimide precursor. Please refer to the following results: 【0087】 [Table 4] 【0088】 Example 20 The formulations of Example 4 and Comparative Example 16 were tested for lithography performance as described above. The formulation of Example 4 had a resolution of 5 micrometers, and the formulation of Comparative Example 16 had a resolution of 7 micrometers. 【0089】 This disclosure further encompasses the following aspects: 【0090】 Embodiment 1: A method for reducing the dissipation rate and linear expansion coefficient of a film formed from a selected polyimide precursor, wherein the selected polyimide precursor contains an ethylenically unsaturated polyimide available for free radical reactions, and the polyimide precursor is given the formula: (R')2-C=C(R')-L-[C(R')=C(R')2] n (In the formula, R' is independently H or an alkyl group of 1 to 3 carbon atoms in each occurrence, L is a hydrocarbon group of 2 to 10 carbon atoms, preferably 2 to 8, more preferably 2 to 7, and even more preferably 2 to 6 carbon atoms, and L is a hydrocarbon group of the formula -C(=O)-(O) m A method comprising: forming a coating composition by combining a crosslinking agent having the formula -R'' (wherein R'' is 1 to 6, preferably 1 to 3, more preferably 1 or 2, alkylene groups of carbon atoms, and m is 0 or 1) or L having the formula -R'''-O-R'''- (wherein R''' is independently 1 to 6, preferably 1 to 3, more preferably 1 or 2, alkylene groups of carbon atoms in each occurrence, and n is 1, 2, or 3), a photoinitiator, and a solvent; applying the coating composition to a substrate; drying to remove the solvent to form a solid coating; exposing the solid coating to radiation of an activation wavelength to react the crosslinking agent with the ethylenically unsaturated polyimide precursor; and curing to form a film. 【0091】 Embodiment 2: The method according to Embodiment 1, wherein L comprises 2 to 6, preferably 2 to 5, aliphatic hydrocarbon groups of carbon atoms, and L has the formula -C(=O)-O-R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms), or L has the formula -R''-O-R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms) and n is 1. 【0092】 Embodiment 3: The method according to Embodiment 1, wherein L comprises a cyclic hydrocarbon with 5 to 7 carbon atoms, preferably 6 carbon atoms, and n is 1 or 2. 【0093】 Embodiment 4: The method according to Embodiment 1, wherein the crosslinking agent comprises allyl methacrylate, 1,2,4-trivinylcyclohexane, or a combination thereof. 【0094】 Embodiment 5: The method according to any one of Embodiments 1 to 4, wherein the film has a dissipation rate of 0.0074 or less, preferably 0.007 or less, and more preferably less than 0.007. 【0095】 Embodiment 6: The method according to any one of Embodiments 1 to 5, wherein the film has a linear thermal expansion coefficient of less than 52, preferably less than 51 ppm / Kelvin. 【0096】 Embodiment 7: A coating composition comprising a polyimide precursor, a photoinitiator, a crosslinking agent, and a solvent, wherein the polyimide precursor contains an ethylenically unsaturated compound usable for free radical reactions, and the crosslinking agent is a compound of the formula (R')2-C=C(R')-LC(R')=C(R')2] n A coating composition having (wherein R' is independently H or an alkyl group of 1 to 3 carbon atoms in each occurrence, L is a linear or branched aliphatic hydrocarbon group of 2 to 7 carbon atoms, L having the formula -C(=O)-O-R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms), or L having the formula -R''-O-R''- (wherein R'' is an alkylene group of 1 to 6 carbon atoms), and n is 1, 2, or 3). 【0097】 Embodiment 8: A coating composition comprising a polyimide precursor, a photoinitiator, a crosslinking agent, and a solvent, wherein the polyimide precursor comprises an ethylenically unsaturated compound available for free radical reactions, and the crosslinking agent comprises a linking group L having five or fewer atoms (excluding pendant atoms and pendant groups) covalently bonded between two ethylenically unsaturated groups, and the polyimide film formed by a step comprising coating the composition onto a substrate, drying to remove the solvent to form a dry coating, and exposing the dry coating to radiation of an activation wavelength to react the crosslinking agent with the polyimide precursor, has a dissipation rate of less than 0.0074, preferably less than 0.007. 【0098】 Embodiment 9: The linking group L is a linear aliphatic hydrocarbon with 2 to 5 carbon atoms, or an alicyclic hydrocarbon with 5 to 7 carbon atoms, or a structure 【0099】 [ka] The coating composition according to embodiment 8, having (wherein R is a divalent hydrocarbon of 1 to 3 carbon atoms, -O-CH2-, or -O-CH2-CH2-). 【0100】 Embodiment 10: The coating composition according to Embodiment 8, wherein the crosslinking agent comprises 1,2,4-trivinylcyclohexane, allyl methacrylate, or a combination thereof. 【0101】 Embodiment 11: A coating composition comprising a polyimide precursor, a photoinitiator, a crosslinking agent, and a solvent, wherein the polyimide precursor contains an ethylenically unsaturated compound available for free radical reactions, and the crosslinking agent is of the formula: (R')2-C=C(R')-L-[C(R')=C(R')2] nA coating composition comprising the steps of applying the composition to a substrate, drying to remove the solvent to form a dry coating, and exposing the dry coating to radiation of an activation wavelength to react a crosslinking agent with a polyimide precursor, wherein the polyimide film formed by these steps has a dissipation rate of less than 0.0074, preferably less than 0.007. 【0102】 Embodiment 12: A coating composition according to any one of Embodiments 1 to 6 or any one of Embodiments 7 to 11, wherein the polyimide precursor comprises a polyamic acid, a polyamic acid ester, or a combination thereof. 【0103】 Embodiment 13: A coating composition according to any one of Embodiments 1 to 6 or any one of Embodiments 7 to 11, wherein the polyimide precursor comprises repeating units formed from the reaction of dianhydride monomers including 4,4'-bisphenyl A diphthalic anhydride, hydroquinone diphthalic anhydride, oxydiphthalic anhydride, biphenyltetracarboxylic dianhydride, bicyclo[2.2.2]octo-7-ene-2,3,5,6-tetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, cyclobutanetetracarboxylic dianhydride, p-phenylenebis(trimellitate) dianhydride, 2,3,5-tricarboxycyclopentylacetic acid-1,4:2,3-dianhydride, or a combination of two or more thereof. 【0104】 Embodiment 14: A coating composition according to any one of Embodiments 1 to 6 or any one of Embodiments 7 to 13, wherein the polyimide precursor comprises repeating units formed from diamine monomers selected from oxydianiline, 4-dimethylaminopyridine, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, isophoronediamine, 4-aminophenylsulfone, 2,2'-bis(trifluoromethyl)benzidine, 4,4'-methylenebis(2-methylcyclohexyl-amine), 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 1,3'-bis(3-aminophenoxy)benzene, p-phenylenediamine, or m-xylenediamine, or combinations of two or more thereof. 【0105】 Embodiment 15: The polyimide precursor is of formula (1) 【0106】 [ka] (wherein X1 is a tetravalent aromatic group or alicyclic group, preferably aromatic, with the -COOR1 group and -CONH- group in the ortho position relative to each other, and the -COOR2 group and -CO- group in the ortho position relative to each other, Y1 is a divalent aromatic group or alicyclic group, preferably aromatic, and R1 and R2 are independently a hydrogen atom, a group represented by the following formula (2) or formula (3), or an aliphatic hydrocarbon group having 1 to 4 carbon atoms, and at least one of R1 and R2 is a group represented by the following formula (2) or formula (3), 【0107】 [ka] or [ka] A coating composition according to any one of embodiments 1 to 6 or any one of embodiments 7 to 11, comprising a repeating unit of the formula, wherein R3 to R5 are independently hydrogen atoms or aliphatic hydrocarbon groups having 1 to 3 carbon atoms, and m is an integer from 1 to 10, preferably an integer from 2 to 5, more preferably 2 or 3. 【0108】 Embodiment 16: A coating composition according to any one of Embodiments 1 to 6 or any one of Embodiments 7 to 14, wherein the polyimide precursor is partially esterified with an ethylenically unsaturated compound, preferably an ethylenically unsaturated alcohol (preferably having 3 to 8 carbon atoms, more preferably 4 to 6 carbon atoms), or a hydroxyalkyl (meth)acrylate, more preferably hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), hydroxybutyl methacrylate (HBMA), or 4-penten-1-ol. 【0109】 Embodiment 17: A coating composition according to any one of Embodiments 7 to 16, further comprising one or more of a photosensitizer, a corrosion inhibitor, a decontaminant, and an adhesion promoter. 【0110】 Aspect 18: A method comprising applying a coating composition according to any one of aspects 7 to 17 to a substrate, drying it to form a dry coating, exposing the coating to radiation of an activation wavelength, and curing it to form a polyimide film. 【0111】 Embodiment 19: The method according to Embodiment 18, wherein exposure to radiation of an activation wavelength is performed in an image-like manner, and the unexposed areas are removed before hardening. 【0112】 Embodiment 20: An article made by the method of Embodiment 18 or 19, wherein the polyimide film is characterized by a dissipation rate of 0.0074 or less, preferably less than 0.007, as determined by the Kent method, and a linear thermal expansion coefficient of less than 52 ppm / Kelvin, as determined by thermomechanical analysis. 【0113】 All ranges disclosed herein include endpoints, which can be combined independently of each other (for example, the range “up to 25% by weight, or more specifically, 5% to 20% by weight” includes the endpoints and all intermediate values ​​of the range “5% to 25% by weight”, etc.). Furthermore, the upper and lower limits described may be combined to form a range (for example, “at least 1 or at least 2% by weight” and “up to 10 or 5% by weight” may be combined as the range “1 to 10% by weight”, or “1 to 5% by weight”, or “2 to 10% by weight”, or “2 to 5% by weight”). 【0114】 This disclosure may, alternatively, include, consist of, or essentially consist of any suitable components disclosed herein. This disclosure may, additionally or alternatively, be formulated to lack, or substantially contain, any components, materials, ingredients, adjuvants, or species used in prior art compositions or not otherwise necessary for achieving the functions and / or purposes of this disclosure. 【0115】 All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if any terminology in this application conflicts with or is inconsistent with any terminology in any of the incorporated references, the terminology from this application shall prevail over the conflicting terminology from the incorporated references. 【0116】 Unless otherwise indicated herein, all test standards are the most current standards in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

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