Polyimide resin, polyimide varnish, polyimide film, and temporary fixing material composition

Abstract

Provided are: a polyimide resin that has a low elastic modulus, that achieve both a low glass transition temperature and heat resistance, that has excellent chemical resistance, and that dissolves in a solvent that is safer than NMP or the like at room temperature; a polyimide film; a polyimide varnish containing the polyimide resin; and a temporary fixing material composition containing the polyimide resin.　This polyimide resin has a structural unit A derived from tetracarboxylic dianhydride and a structural unit B derived from a diamine. The structural unit A includes a structural unit (A1') derived from at least one selected from the group consisting of a compound represented by formula (a1) and a compound represented by formula (a2). The structural unit B includes a structural unit (B1') derived from a compound represented by formula (B1). (In formula (B1), each X1 independently represents a divalent hydrocarbon group having 1-7 carbon atoms, -O-, -S-, -SO2-, or -CO-, and n represents an integer of 4-10.)

Description

Polyimide resin, polyimide varnish, polyimide film, and temporary fixing material composition

[0001] The present invention relates to a polyimide resin, a polyimide varnish, a polyimide film, and a temporary fixing material composition.

[0002] In recent years, the weight reduction and thinning of semiconductor electronic components have been progressing. In 2.5D or 3D semiconductor packaging, due to the high integration and high density of semiconductor devices, techniques have been developed to thin semiconductor chips and stack them in multiple layers while connecting them with through-silicon vias (TSVs). In the field of power semiconductors, to reduce conduction losses for energy conservation, the thinning of semiconductor electronic circuit boards has been underway. As a method of thinning the semiconductor electronic circuit forming substrate, for example, grinding is performed on the non-circuit forming surface (the back surface) of the semiconductor electronic circuit forming substrate. Conventionally, in the grinding process, a back grind tape (protective tape) is attached to the opposite side of the grinding surface to prevent breakage during grinding. However, the back grind tape has insufficient heat resistance and is not suitable for high-temperature processes in the above-mentioned TSV and power semiconductor fields. Therefore, a method has been proposed in which a semiconductor electronic circuit forming substrate is fixed to a support substrate such as a supportive silicon wafer or glass substrate via a temporary fixing material (adhesive layer), and after grinding, back surface circuit formation processing, etc., the processed semiconductor circuit forming substrate is peeled off from the support substrate.

[0003] Polyimide adhesives are known as temporary fixing materials for fixing a support substrate to a semiconductor electronic circuit forming substrate. For example, Patent Document 1 reports a polyimide resin composition for a temporary fixing material containing a polar solvent and a polyimide resin with a viscosity average molecular weight η of 0.6 to 1.60. Patent Document 2 reports a polyamic acid varnish having no ester bond, amide bond, and ether bond and having a linear alkylene group. In Patent Document 3, a temporary fixing material composition has been proposed in which a support substrate is pressure-bonded to a semiconductor electronic circuit forming substrate using an adhesive for temporary bonding containing a low-volatility, high-polarity solvent, heat-treated at 300°C or higher, and then the support substrate and the adhesive for temporary bonding are solvent-peeled off with a volatile solvent.

[0004] International Publication No. 2013 / 183293, International Publication No. 2023 / 74534, Patent No. 7183840

[0005] Temporary fixing materials used to secure support substrates to semiconductor electronic circuit formation substrates require heat resistance, peelability, and low-temperature drying and bonding properties to withstand the manufacturing processes of semiconductor electronic components. In particular, in the field of power semiconductors, heat resistance of 350°C or higher is required during the annealing and back metal processes after ion implantation. On the other hand, in order to save energy in the process and improve productivity, it is necessary that the temporary fixing material can be dried and bonded at lower temperatures when the film is formed, and that it can be easily peeled off after the heat treatment process is completed. Furthermore, it is preferable to use solvents with low toxicity for film formation and peeling of the temporary fixing material. Patent documents 1 to 3 use polyimide varnish or polyamic acid varnish dissolved in N-methyl-2-pyrrolidone (NMP), but it is desirable to use safe solvents. On the other hand, in order to save energy in the process and improve productivity, it is preferable that the film formation and bonding of the temporary fixing material can be carried out at lower temperatures. In Patent Document 3, imidation is performed at a high temperature of 400°C for 1 hour to form a temporary adhesive film on the support substrate. Therefore, there is a need for a temporary fixing material that can bond a film-forming and semiconductor electronic circuit formation substrate to a support substrate at low temperatures, can pass through the manufacturing process of semiconductor electronic components that involves heat treatment at 350°C or higher, and can be peeled off without leaving any residue. The object of the present invention is to provide a polyimide resin, a polyimide film, a polyimide varnish containing the polyimide resin, and a temporary fixing material composition containing the polyimide resin that have a low elastic modulus, achieve both a low glass transition temperature and heat resistance, have excellent chemical resistance, and dissolve at room temperature in solvents that are safer than NMP.

[0006] The inventors have discovered that a polyimide resin containing a combination of structural units derived from a specific tetracarboxylic dianhydride and structural units derived from a specific diamine can solve the above problems, and have completed the invention.

[0007] That is, the present invention relates to the following <1> to <7>. <1> A polyimide resin having constituent unit A derived from a tetracarboxylic dianhydride and constituent unit B derived from a diamine, wherein constituent unit A includes constituent unit (A1') derived from one or more compounds selected from the group consisting of compounds represented by the following formula (a1) and compounds represented by the following formula (a2), A polyimide resin containing a constituent unit (B1') whose constituent unit B is derived from a compound represented by the following formula (B1). (In formula (B1), X 1 Each of these is independently a divalent hydrocarbon group having 1 to 7 carbon atoms, -O-, -S-, -SO2-, or -CO-, and n is an integer from 4 to 10.) <2> The polyimide resin according to <1>, wherein the constituent unit B further includes a constituent unit (B2') derived from a compound represented by the following formula (B2), and the ratio of the constituent unit (B2') in the constituent unit B is greater than 0 mol% and less than or equal to 70 mol%. (In the formulas, Z is independently -O-, -COO-, -OCO-, -C(CH3)2-, or -C(CF3)2-.) <3> The polyimide resin according to <2>, wherein the compound represented by formula (B1) is the compound represented by the following formula (b1), and the compound represented by formula (B2) is the compound represented by the following formula (b2). A polyimide varnish containing the polyimide resin and organic solvent described in any one of <4> <1> to <3>. A polyimide film containing the polyimide resin described in any one of <5> <1> to <3>. A temporary fixing material composition containing the polyimide resin described in any one of <6> <1> to <3>. A method for thinning a semiconductor wafer, comprising: step 1 applying the temporary fixing material composition described in <6> to a semiconductor wafer or support substrate to form an adhesive layer for temporary fixing; step 2 temporarily fixing the support substrate to the semiconductor wafer via the adhesive layer; step 3 grinding the back surface of the semiconductor wafer while the support substrate is temporarily fixed to the semiconductor wafer via the adhesive layer; and step 4 peeling off the support substrate.

[0008] According to the present invention, it is possible to provide a polyimide resin, a polyimide film, a polyimide varnish containing the polyimide resin, and a temporary fixing material composition containing the polyimide resin, which have a low elastic modulus, achieve both a low glass transition temperature and heat resistance, have good chemical resistance and dissolve in safe solvents at room temperature.

[0009] [Polyimide Resin] The polyimide resin of the present invention is a polyimide resin having constituent units A derived from tetracarboxylic dianhydride and constituent units B derived from diamine, wherein constituent unit A includes constituent units (A1') selected from the group consisting of compounds represented by the following formula (a1) and compounds represented by the following formula (a2), The constituent unit B contains a constituent unit (B1') derived from the compound represented by the following formula (B1). (In formula (B1), X 1 Each of these is independently a divalent hydrocarbon group having 1 to 7 carbon atoms, -O-, -S-, -SO2-, or -CO-, and n is an integer from 4 to 10.

[0010] The polyimide resin of the present invention exhibits a low elastic modulus, achieving both a low glass transition temperature and heat resistance, excellent chemical resistance, and solubility in safe solvents at room temperature. This is because the polyimide resin has constituent units derived from specific tetracarboxylic dianhydrides having an alicyclic structure that suppresses intermolecular interactions due to CT complex formation while possessing a certain degree of rigidity, and constituent units derived from aromatic diamines having linear alkyl chains. This allows it to achieve both a high weight loss temperature and a low glass transition temperature, which are contradictory properties. In the thinning process of semiconductor wafers, it is considered to have chemical resistance to chemicals during the process and solvent solubility necessary for peeling when applied to and temporarily fixed to semiconductor wafers or support substrates. Because the polyimide resin of the present invention has excellent solvent solubility, the range of solvents that can be used in varnish and temporary fixing material compositions is broadened, and it becomes possible to manufacture varnish and temporary fixing material compositions using highly safe solvents. The polyimide resin will be described in detail below.

[0011] <Constituent Unit A> Constituent unit A is a constituent unit derived from tetracarboxylic dianhydride in the polyimide resin. Constituent unit A includes one or more constituent units (A1') selected from the group consisting of compounds represented by the following formula (a1) and compounds represented by the following formula (a2).

[0012] The inclusion of constituent unit (A1') in constituent unit A results in a polyimide resin with a low modulus of elasticity, achieving both a low glass transition temperature and high thermal decomposition resistance, as well as excellent chemical resistance and solvent solubility. Constituent unit A is considered to contribute particularly to achieving both a low glass transition temperature and high thermal decomposition resistance, as well as to good chemical resistance and solvent solubility.

[0013] The compound represented by formula (a1) is dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride (H-BPDA), and the compound represented by formula (a2) is cyclohexane-1,2,4,5-tetracarboxylic dianhydride (HPMDA). Commercially available products include dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride (H-BPDA) manufactured by Tokyo Chemical Industry Co., Ltd. and cyclohexane-1,2,4,5-tetracarboxylic dianhydride (HPMDA) manufactured by Mitsubishi Gas Chemical Corporation.

[0014] That is, constituent unit A includes one or more selected from the group consisting of constituent unit (a1') derived from the compound represented by formula (a1) and constituent unit (a2') derived from the compound represented by formula (a2). From the viewpoint of low elastic modulus and low glass transition temperature, it includes constituent unit (a1') derived from the compound represented by formula (a1), and from the viewpoint of heat resistance, it includes constituent unit (a2') derived from the compound represented by formula (a2). The compound represented by formula (a1) has a certain degree of rigidity while having an alicyclic structure that can suppress intermolecular interactions due to CT complex formation. The compound represented by formula (a2) also has a certain degree of rigidity and an alicyclic structure that can suppress intermolecular interactions due to CT complex formation, similar to the compound represented by formula (a1). Furthermore, since the compound represented by formula (a2) has higher rigidity than the compound represented by formula (a1), it has excellent heat resistance and is suitable for use in high-temperature environments. By having one or more constituent units A selected from the group consisting of constituent units (a1') and (a2'), the polyimide resin of the present invention can have a low glass transition temperature despite high heat resistance, and can also possess the chemical resistance and solvent solubility necessary for the semiconductor wafer thinning process.

[0015] The proportion of constituent unit (A1') in constituent unit A is preferably 80 mol% or more, more preferably 90 mol% or more, and preferably 100 mol% or less. Constituent unit (A1') includes one or more selected from the group consisting of constituent units (a1') and (a2'). It is preferable that the proportion of constituent unit (a1') or constituent unit (a2') in constituent unit (A1') be 80 mol% or more, more preferably 90 mol% or more, and even more preferably 100 mol%.

[0016] The constituent unit A may include constituent units other than constituent unit (A1'). Compounds that give such constituent units are not particularly limited, but include aromatic tetracarboxylic dianhydrides, aliphatic tetracarboxylic dianhydrides, and alicyclic tetracarboxylic dianhydrides other than the compound represented by formula (a1) and the compound represented by formula (a2). Aromatic tetracarboxylic dianhydrides include 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), pyromellitic anhydride (PMDA), 4,4-bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-ylcarbonyloxy)biphenyl (BP-TME), 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorendioanhydride (BPF-PA), 2,3,6,7-naphthalenetetracarboxylic 2,3:6,7-dianhydride (NTCDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 9,9-bis(trifluoromethyl)-9H-xanthene-2, Examples include 3,6,7-tetracarboxylic dianhydride (6FCDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]hexafluoropropane dianhydride, 4,4'-oxydiphthalic anhydride (ODPA), 2,2-bis(3,4-dicarboxyphenyl)-propane dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF), hydroquinone diphthalic anhydride (HQDEA), ethylene glycol bis(trimellitate) dianhydride (TMEG), and p-phenylene bis(trimellitate) dianhydride (TAHQ).

[0017] Examples of aliphatic tetracarboxylic dianhydrides include 1,2,3,4-butanetetracarboxylic dianhydride.

[0018] Other alicyclic tetracarboxylic dianhydrides besides the compound represented by formula (a1) and the compound represented by formula (a2) include norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5',6,6'-tetracarboxylic anhydride (CpODA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, and 1,2,3,4-cyclopenta Examples include diantetracarboxylic acid dianhydride, 1,2,4,5-cyclopentanetetracarboxylic acid dianhydride, 2,2-propyridene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2.2.2]octo-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, and bicyclo[4.4.0]decane-2,3,6,7-tetracarboxylic acid dianhydride.

[0019] In this specification, aromatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more aromatic rings, alicyclic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing one or more alicyclic rings but no aromatic rings, and aliphatic tetracarboxylic dianhydride means a tetracarboxylic dianhydride containing neither aromatic nor alicyclic rings. The constituent units optionally included in constituent unit A may be one type or two or more types.

[0020] <Constituent Unit B> Constituent unit B includes a constituent unit (B1') derived from the compound represented by the following formula (B1). (In formula (B1), X 1 Each of these is independently a divalent hydrocarbon group having 1 to 7 carbon atoms, -O-, -S-, -SO2-, or -CO-, and n is an integer from 4 to 10.

[0021] The polyimide resin of the present invention, by having a constituent unit (B1'), achieves both a low glass transition temperature and high heat resistance, while also possessing the chemical resistance and solvent solubility necessary for the thinning process of semiconductor wafers. The rigid and linear constituent unit (B1'), having an aliphatic chain and two aromatic rings, is thought to contribute to the high heat resistance and low elastic modulus necessary for adhesion of the polyimide resin.

[0022] In equation (B1), X 1 Each of these independently represents a divalent hydrocarbon group having 1 to 7 carbon atoms, -O-, -S-, -SO2-, or -CO-. The divalent hydrocarbon group having 1 to 7 carbon atoms is a chain-like hydrocarbon group such as an alkylene group, alkenylene group, or alkynylene group. Examples of the alkylene group include a methylene group, ethylene group, trimethylene group, dimethylmethylene group, tetramethylene group, 2-methyltrimethylene group, hexamethylene group, and heptamethylene group. Examples of the alkenylene group include a vinylene group, propenylene group, 1-butenylene group, 2-butenylene group, pentenylene group, hexenylene group, and heptenylene group. Examples of the alkynylene group include ethynylene, 1-propynylene, 2-propynylene, butynylene, pentynylene, hexynylene, and heptynylene groups. 1 n is preferably at least one selected from the group consisting of -O- and -C(CH3)2-, and more preferably -O-. n is an integer from 4 to 10, preferably an integer from 4 to 8, and more preferably an integer from 4 to 7.

[0023] The compound represented by formula (B1) preferably comprises X in formula (B1). 1 The compound represented by the following formula (b1), where is O and n is 5, is 1,5-bis(4-aminophenoxy)pentane.

[0024] The proportion of constituent unit (B1') in constituent unit B is preferably 25 mol% or more, more preferably 30 mol% or more, even more preferably 50 mol% or more, and from the viewpoint of heat resistance, low modulus of elasticity, and chemical resistance, it is even more preferably 75 mol% or more, even more preferably 85 mol% or more, even more preferably 95 mol% or more, and preferably 100 mol% or less. In other words, constituent unit B may consist only of constituent unit (B1').

[0025] Constituent unit B may consist only of constituent unit (B1'), or it may include constituent unit (B2') derived from the compound represented by the following formula (B2) in addition to constituent unit (B1'). (In the formula, Z is independently -O-, -COO-, -OCO-, -C(CH3)2-, or -C(CF3)2-.) Specific examples of compounds represented by formula (B2) include 1,3-bis(3-aminophenoxy)benzene (TPE-M), 1,3-bis[2-(3-aminophenyl)-2-propyl]benzene, and 1,3-bis[2-(3-aminophenyl)-2-hexafluoropropyl]benzene. Of these, the compound represented by the following formula (b2), namely 1,3-bis(3-aminophenoxy)benzene (TPE-M), is more preferred.

[0026] The polyimide resin of the present invention preferably comprises a constituent unit B which is derived from a compound represented by formula (B1) and a constituent unit B which is derived from a compound represented by formula (B2), wherein the compound represented by formula (B1) is the compound represented by the following formula (b1), and the compound represented by formula (B2) is the compound represented by the following formula (b2).

[0027] If constituent unit B further contains constituent unit (B2'), the ratio of constituent unit (B2') in constituent unit B is preferably greater than 0 mol% and 70 mol% or less, more preferably 30 to 70 mol%, and even more preferably 40 to 70 mol%.

[0028] The proportion of constituent unit (B2') in the total of constituent units (B1') and (B2') is preferably 50 mol% or more, more preferably 60 mol% or more, and preferably 70 mol% or less. The molar ratio of constituent unit (B1') to constituent unit (B2') in constituent unit B [(B1') / (B2')] is preferably 30 / 70 to 90 / 10, more preferably 30 / 70 to 80 / 20, and even more preferably 30 / 70 to 50 / 50, and even more preferably 30 / 70 to 40 / 60, from the viewpoint of reducing the elastic modulus and improving adhesion and heat resistance.

[0029] The ratio of the total constituent units (B1') and (B2') in constituent unit B is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less. Constituent unit B may consist only of constituent units (B1') and (B2').

[0030] Constituent unit B may include constituent units other than constituent units (B1') and (B2'). Examples of diamines that give such constituent units are not particularly limited, but include aromatic diamines, alicyclic diamines, and aliphatic diamines that do not include either the compound represented by formula (B1) or the compound represented by formula (B2).

[0031] Aromatic diamines include 4-aminophenyl-4-aminobenzoate (4-BAAB), bis(4-aminophenyl) terephthalate (APTP), 1,4-bis(4-aminobenzoyloxy)benzene, 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA), 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (2,2'-TFMB), 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-5,5 '-diaminobiphenyl, 2,2-bis(4-aminophenyl)hexafluoropropane (HFDA), 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP), 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (DDM), 4,4'-diaminodiphenylsulfone (4,4'-DDS), 3,3'-diaminodiphenyl Lusulfone (3,3'-DDS), 4,4'-diamino-2,2'-dimethylbiphenyl (mTB), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4,4'-diaminobiphenyl (benzidine), 4,4'-diamino-3,3'-dimethylbiphenyl, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminobenzophenone, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 5-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indan (5 -TMDM), 6-amino-1,3,3-trimethyl-1-(4-aminophenyl)-indan (6-TMDM), 1,4-bis(4-amino-α,α-dimethylbenzyl)benzene (BisAP), 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl (BODA), 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 1,4-bis(3-aminophenoxy)benzene, 1,4,4'-Bis(4-aminophenoxy)benzene, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4'-diaminobenzanilide, 4-aminobenzoic acid-4-aminophenyl, 3,4-diaminobenzanilide, and the like can be mentioned.

[0032] As the alicyclic diamine, 1,3-bis(aminomethyl)cyclohexane (1,3-BAC), 1,4-bis(aminomethyl)cyclohexane, 1,3-cyclohexyldiamine, 1,4-cyclohexyldiamine, isophoronediamine, bis(aminomethyl)norbornane, 4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexyl ether, 2,2-bis(4-aminocyclohexyl)propane, and the like can be mentioned.

[0033] As the aliphatic diamine, ethylenediamine, hexamethylenediamine, and the like can be mentioned.

[0034] In this specification, the aromatic diamine means a diamine containing one or more aromatic rings, the alicyclic diamine means a diamine containing one or more alicyclic rings and no aromatic rings, and the aliphatic diamine means a diamine containing neither an aromatic ring nor an alicyclic ring. The constituent units optionally contained in the constituent unit B may be one kind or two or more kinds.

[0035] <Properties of the polyimide resin> From the viewpoint of the mechanical strength of the obtained polyimide film, the number average molecular weight of the polyimide resin is preferably 5,000 to 300,000. The number average molecular weight of the polyimide resin can be determined, for example, from the standard polymethyl methacrylate (PMMA) conversion value by gel permeation chromatography.

[0036] The polyimide resin may contain a structure other than the polyimide chain (a structure in which the constituent unit A and the constituent unit B are imide-bonded). Examples of the structure other than the polyimide chain that can be contained in the polyimide resin include a structure containing an amide bond and the like. The polyimide resin preferably contains the polyimide chain (a structure in which the constituent unit A and the constituent unit B are imide-bonded) as the main structure. Therefore, the ratio of the polyimide chain in the polyimide resin is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 90% by mass or more, even more preferably 99% by mass or more, and preferably 100% by mass or less. That is, the polyimide resin of the present invention may consist only of the polyimide chain.

[0037] [Method for Producing Polyimide Resin] There is no particular limitation on the method for producing the polyimide resin of the present invention, but a method of obtaining a polyimide resin by reacting a compound (tetracarboxylic acid component) that provides the above-described constituent unit A and a compound (diamine component) that provides the above-described constituent unit B is preferable. By this method, a polyimide resin can be directly obtained from the tetracarboxylic acid component and the diamine component.

[0038] In this production method, the polyimide resin can be produced by reacting a tetracarboxylic acid component containing a compound that provides the above-described constituent unit (A1') and a diamine component containing a compound that provides the above-described constituent unit (B1').

[0039] Examples of the compound that provides the constituent unit (B1') include, but are not limited to, the compound represented by the formula (B1), and derivatives thereof may be used as long as they provide the same constituent unit. Examples of such derivatives include diisocyanates corresponding to the compound (diamine) represented by the formula (B1).

[0040] The diamine component may contain structural units other than structural unit (B1'), and preferably may contain structural unit (B2') derived from the compound represented by formula (B2). When the diamine component contains structural unit (B2'), the compound that gives structural unit (B2') is the compound represented by formula (B2), but is not limited to that, and may be a derivative thereof within the range of giving the same structural unit. Examples of such derivatives include diisocyanates corresponding to the compound (diamine) represented by formula (B2).

[0041] In the diamine component, the molar ratio [(B1') / (B2')] of the compound that gives the constituent unit (B1') to the compound that gives the constituent unit (B2') is preferably 30 / 70 to 90 / 10, more preferably 30 / 70 to 80 / 20, even more preferably 30 / 70 to 50 / 50, and even more preferably 30 / 70 to 40 / 60, from the viewpoint of reducing the elastic modulus and improving adhesion and heat resistance.

[0042] The ratio of the compound that gives the constituent unit (B1') in the diamine component is preferably 25 mol% or more, preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 75 mol% or more, even more preferably 85 mol% or more, even more preferably 95 mol% or more, and preferably 100 mol% or less.

[0043] When the diamine component contains a compound that provides the constituent unit (B2'), the ratio of the compound that provides the constituent unit (B2') in the diamine component is preferably 50 mol% or more, more preferably 60 mol% or more, and preferably 70 mol% or less.

[0044] The total ratio of the compound that gives the constituent unit (B1') and the compound that gives the constituent unit (B2') in the diamine component is preferably 70 mol% or more, more preferably 70 mol% or more, even more preferably 90 mol% or more, and preferably 100 mol% or less. The diamine component may consist only of the compound that gives the constituent unit (B1') and the compound that gives the constituent unit (B2').

[0045] In the present invention, in addition to the tetracarboxylic acid component and diamine component described above, an end-cap encapsulant may be used in the production of the polyimide resin. Monoamines or dicarboxylic acids are preferred as the end-cap encapsulant. The amount of end-cap encapsulant to be introduced is preferably 0.0001 to 0.1 moles, and more preferably 0.001 to 0.06 moles, per mole of tetracarboxylic acid component. Examples of monoamine end-cap encapsulants include methylamine, ethylamine, propylamine, butylamine, benzylamine, 4-methylbenzylamine, 4-ethylbenzylamine, 4-dodecylbenzylamine, 3-methylbenzylamine, 3-ethylbenzylamine, aniline, 3-methylaniline, 4-methylaniline, etc., with benzylamine and aniline being preferred. Dicarboxylic acids are preferred as the end-cap encapsulant, and a portion thereof may be ring-closed. Examples include phthalic acid, phthalic anhydride, 4-chlorophthalic acid, tetrafluorophthalic acid, 2,3-benzophenone dicarboxylic acid, 3,4-benzophenone dicarboxylic acid, cyclohexane-1,2-dicarboxylic acid, cyclopentane-1,2-dicarboxylic acid, and 4-cyclohexene-1,2-dicarboxylic acid, with phthalic acid and phthalic anhydride being preferred.

[0046] There are no particular restrictions on the method of reacting the tetracarboxylic acid component and the diamine component as described above, and known methods can be used. For example, (1) a method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor, stirred at 0 to 80°C for 0.5 to 30 hours, and then the temperature is raised to carry out the imidation reaction; (2) a method in which the diamine component and the reaction solvent are charged into a reactor and dissolved, then the tetracarboxylic acid component is charged, stirred at room temperature to 80°C for 0.5 to 30 hours as needed, and then the temperature is raised to carry out the imidation reaction; (3) a method in which the tetracarboxylic acid component, the diamine component, and the reaction solvent are charged into a reactor and the temperature is immediately raised to carry out the imidation reaction.

[0047] The organic solvents (reaction solvents) used in the production of polyimide resins should not inhibit the imidation reaction and should be able to dissolve the resulting polyimide resin. Examples include aprotic solvents, phenolic solvents, etheric solvents, and carbonate solvents.

[0048] Specific examples of aprotic solvents include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylcaprolactam, 1,3-dimethylimidazolidinone, tetramethylurea, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide; lactone solvents such as γ-butyrolactone (GBL) and γ-valerolactone; glycol solvents such as diethylene glycol dimethyl ether, triethylene glycol, and triethylene glycol dimethyl ether; phosphorus-containing amide solvents such as hexamethylphosphoric amide and hexamethylphosphinetriamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; ketone solvents such as acetone, cyclopentanone, cyclohexanone, and methylcyclohexanone; amine solvents such as picoline and pyridine; and ester solvents such as acetic acid (2-methoxy-1-methylethyl).

[0049] Specific examples of phenolic solvents include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, and 3,5-xylenol. Specific examples of etheric solvents include 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, 1,2-bis(2-methoxyethoxy)ethane, bis[2-(2-methoxyethoxy)ethyl] ether, tetrahydrofuran, and 1,4-dioxane. Specific examples of carbonateic solvents include diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate. Among the above reaction solvents, aprotic solvents are preferred, and among these, amide solvents and lactone solvents are more preferred, with lactone solvents being even more preferred. The above reaction solvents may be used individually or in mixtures of two or more.

[0050] In the imidation reaction, it is preferable to carry out the reaction while removing the water generated during production using a Dean-Stark apparatus or similar device. By performing such an operation, the degree of polymerization and the imidation rate can be further increased.

[0051] In the above imidation reaction, known imidation catalysts can be used. Examples of imidation catalysts include base catalysts and acid catalysts. Examples of base catalysts include organic base catalysts such as pyridine, quinoline, isoquinoline, α-picoline, β-picoline, 2,4-lutidine, 2,6-lutidine, trimethylamine, triethylamine (TEA), tripropylamine, tributylamine, triethylenediamine, imidazole, N,N-dimethylaniline, and N,N-diethylaniline, and inorganic base catalysts such as potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate. Examples of acid catalysts include crotonic acid, acrylic acid, trans-3-hexenoic acid, cinnamic acid, benzoic acid, methylbenzoic acid, oxybenzoic acid, terephthalic acid, benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid. The above imidation catalysts may be used individually or in combination of two or more types. Of the above, from the viewpoint of ease of handling, it is preferable to use a base catalyst, more preferable to use an organic base catalyst, and even more preferable to use at least one selected from the group consisting of triethylamine and triethylenediamine.

[0052] The temperature of the imidation reaction is preferably 120 to 250°C, more preferably 160 to 200°C, from the viewpoint of the reaction rate and suppression of gelation, etc. The reaction time is preferably 0.5 to 10 hours after the start of distillation of the generated water.

[0053] [Polyimide Varnish and Temporary Fixing Composition] The polyimide varnish of the present invention is obtained by dissolving the polyimide resin of the present invention in an organic solvent. The organic solvent can be any solvent that dissolves the polyimide resin and is not particularly limited, but it is preferable to use the above-mentioned compounds individually or in a mixture of two or more as the reaction solvent used in the production of the polyimide resin. The polyimide varnish of the present invention may be the polyimide solution itself obtained by dissolving the polyimide resin obtained by polymerization in a reaction solvent, or it may be a polyimide solution that has been further diluted by adding a solvent.

[0054] Since the polyimide resin of the present invention is solvent-soluble, it can be used to produce a stable, high-concentration varnish at room temperature. The polyimide varnish of the present invention preferably contains 5 to 40% by mass of the polyimide resin of the present invention, and more preferably 10 to 30% by mass. The viscosity of the polyimide varnish is preferably 1 to 200 Pa·s, more preferably 1 to 100 Pa·s. The viscosity of the polyimide varnish is the value measured at 25°C using an E-type viscometer. Furthermore, the polyimide varnish of the present invention may contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, defoamers, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitive agents, as long as they do not impair the required properties of the polyimide resin and temporary fixative. The method for producing the polyimide varnish of the present invention is not particularly limited, and known methods can be applied.

[0055] The temporary fixing material composition of the present invention contains the polyimide resin. Therefore, the polyimide varnish can also be used as a temporary fixing material composition. Preferably, the temporary fixing material composition of the present invention is a solution of the polyimide resin of the present invention in an organic solvent. The organic solvent can be any solvent that dissolves the polyimide resin and is not particularly limited, but it is preferable to use the above-mentioned compounds alone or in a mixture of two or more as a reaction solvent used in the production of the polyimide resin. The temporary fixing material composition of the present invention may be the polyimide solution itself in which the polyimide resin obtained by polymerization is dissolved in a reaction solvent, or it may be a solution of which a solvent has been further added to dilute it.

[0056] Since the polyimide resin of the present invention is solvent-soluble, it can be used to make a stable, high-concentration temporary fixing material composition at room temperature. The temporary fixing material composition of the present invention preferably contains 5 to 40% by mass of the polyimide resin of the present invention, and more preferably 10 to 30% by mass. The viscosity of the temporary fixing material composition is preferably 1 to 200 Pa·s, and more preferably 1 to 100 Pa·s. The viscosity of the temporary fixing material composition is the value measured at 25°C using an E-type viscometer. Furthermore, the temporary fixing material composition of the present invention may also contain various additives such as inorganic fillers, adhesion promoters, release agents, flame retardants, ultraviolet stabilizers, surfactants, leveling agents, defoamers, fluorescent whitening agents, crosslinking agents, polymerization initiators, and photosensitive agents, as long as they do not impair the required properties of the polyimide resin and temporary fixing material.

[0057] [Polyimide Film] The polyimide film of the present invention contains the polyimide resin. Therefore, the polyimide film of the present invention has a low elastic modulus, achieves both a low glass transition temperature and heat resistance, and exhibits excellent chemical resistance and solvent solubility.

[0058] The preferred physical properties of the polyimide film of the present invention are as follows: The glass transition temperature is preferably 240°C or lower, more preferably 230°C or lower, and even more preferably 220°C or lower. The 1% weight loss temperature is preferably 400°C or higher, more preferably 410°C or higher, and even more preferably 420°C or higher. The weight loss rate when held at 350°C for 1 hour is preferably 1.5% or lower, more preferably 1.2% or lower, and even more preferably 1.0% or lower. The tensile modulus according to JIS K7127:1999 is preferably 4.0 GPa or lower, more preferably 3.5 GPa or lower, and even more preferably 3.0 GPa or lower.

[0059] The polyimide film of the present invention has good chemical resistance. Specifically, it is resistant to propylene glycol monomethyl ether acetate (PGMEA).

[0060] The polyimide film of the present invention is soluble at room temperature in low-water-absorbent solvents such as γ-butyrolactone (GBL). Therefore, since low-water-absorbent solvents can be used to peel the polyimide film, humidity and moisture have less impact on the semiconductor manufacturing process. GBL is a solvent with a lower environmental impact compared to NMP.

[0061] Therefore, the polyimide film of the present invention can be suitably used as a temporary fixing material by forming the polyimide film of the present invention on a semiconductor electronic circuit formation substrate by the method described below. The above-mentioned physical properties in the present invention can be specifically measured by the method described in the examples.

[0062] There are no particular limitations on the thickness of the polyimide film of the present invention, but when used as a temporary fixing material, it is preferably 1 to 250 μm, more preferably 5 to 100 μm, even more preferably 8 to 80 μm, and even more preferably 10 to 80 μm. The thickness of the polyimide film can be easily controlled by adjusting the solid content concentration and viscosity of the polyimide varnish. Therefore, when using the polyimide film as a temporary fixing material, the thickness can be easily controlled by adjusting the solid content concentration and viscosity of the temporary fixing material composition.

[0063] There are no particular limitations on the method for manufacturing the polyimide film of the present invention, and known methods can be used. For example, one method is to apply the polyimide varnish of the present invention onto a support substrate and heat it. Specifically, one method is to apply it onto a smooth support substrate such as a glass plate, metal plate, or plastic, and then remove organic solvents such as reaction solvents and diluent solvents contained in the polyimide varnish by heating. The polyimide varnish containing the polyimide resin of the present invention is suitably used as a raw material for a temporary fixing material. When using the polyimide film of the present invention as a temporary fixing material, the polyimide varnish is applied onto a semiconductor wafer or a support substrate.

[0064] Known coating methods include spin coating, slit coating, and blade coating. Among these, spin coating is preferred from the viewpoint of improving film uniformity and workability. As a method for removing organic solvents contained in polyimide varnish by heating, it is preferable to evaporate the organic solvent at a temperature of 150°C or lower to make it tack-free, and then dry it at a temperature above the boiling point of the organic solvent used (not particularly limited, but preferably 200 to 350°C). It is also preferable to dry it in an air atmosphere or a nitrogen atmosphere. The pressure of the drying atmosphere may be reduced pressure, atmospheric pressure, or increased pressure. There are no particular limitations on the method for peeling the polyimide film formed on the support substrate from the support substrate, but examples include the laser lift-off method, a method using a sacrificial layer for peeling (a method of applying a release agent to the surface of the support substrate in advance), a method of mechanical peeling by adding a release agent to the varnish, and solvent peeling. When the polyimide film of the present invention is used as a temporary fixing material, methods for peeling it from a laminate consisting of a semiconductor wafer, a temporary fixing material, and a support substrate include dissolving the temporary fixing material with a solvent using a support substrate having a porous structure, peeling it by irradiating it with a laser from the support substrate side, mechanically peeling it by inserting a blade into the interface between the support substrate and the temporary fixing material, and peeling it by softening the temporary fixing material with heat and sliding it off.

[0065] [Method for thinning a semiconductor wafer] The method for thinning a semiconductor wafer according to the present invention comprises: step 1, applying the temporary fixing material composition to a semiconductor wafer that will serve as a support substrate or a support substrate commonly used for forming a polyimide film, to form an adhesive layer for temporary fixing; step 2, temporarily fixing the support substrate to the semiconductor wafer via the adhesive layer; step 3, grinding the back surface of the semiconductor wafer while the support substrate is temporarily fixed to the semiconductor wafer via the adhesive layer; and step 4, peeling off the support substrate.

[0066] Step 1 is a step of applying the temporary fixing material composition to a semiconductor wafer or support substrate to form an adhesive layer for temporary fixing. In this step, it is preferable to form the adhesive layer by the method described in the method for manufacturing the polyimide film. Specifically, this can be done by applying the temporary fixing material composition to a semiconductor wafer or support substrate and then heating it. More specifically, this can be done by applying the temporary fixing material composition to a semiconductor wafer or support substrate and then removing organic solvents such as reaction solvents and diluent solvents contained in the temporary fixing material composition by heating.

[0067] Known coating methods such as spin coating, slit coating, and blade coating can be used to apply the temporary fixing material composition to a semiconductor wafer. Of these, spin coating is preferred from the viewpoint of improving film uniformity and workability. A method for removing the organic solvent contained in the temporary fixing material composition by heating is to heat the material at a temperature of 150°C or lower to evaporate the organic solvent and make it tack-free, and then further heat it to a temperature above the boiling point of the organic solvent used, for example, 200 to 350°C, to dry it. Drying in an air atmosphere or a nitrogen atmosphere is preferable. The pressure of the drying atmosphere may be reduced pressure, atmospheric pressure, or increased pressure. Examples of support substrates include glass substrates, silicon substrates, sapphire substrates, ceramic substrates, etc. A method for applying the temporary fixing material composition to the support substrate is the same as the method for applying the temporary fixing material composition to the semiconductor wafer.

[0068] Step 2 is the process of temporarily fixing the support substrate to the semiconductor wafer via an adhesive layer. There are no restrictions on the method of temporary fixing, but for example, it can be fixed by pressing with a vacuum heat press. Examples of support substrates include glass substrates, silicon substrates, sapphire substrates, ceramic substrates, etc.

[0069] Step 3 is a process of grinding the back surface of the semiconductor wafer while the support substrate is temporarily fixed to the semiconductor wafer via the adhesive layer. The back surface of the semiconductor wafer is the surface of the semiconductor wafer opposite to the surface in contact with the adhesive layer. This step reduces the thickness of the semiconductor wafer. It is preferable to use a grinder to grind the back surface of the semiconductor wafer. It is preferable to supply grinding water or CMP slurry liquid during the grinding process. The thickness of the semiconductor wafer obtained in this step can be adjusted as appropriate depending on the application, but is preferably 5 to 600 μm.

[0070] Step 4 is the step of peeling off the support substrate. In this step, it is preferable to peel off the support substrate using the method described in the manufacturing method of the polyimide film. Specifically, the laser lift-off method, the method of using a sacrificial layer for peeling (a method of applying a release agent to the surface of the support substrate in advance), and the method of mechanically peeling by adding a release agent to the varnish are used. In addition, a method of dissolving the adhesive layer with a solvent using a support substrate having a porous structure, a method of peeling by irradiating with a laser from the support substrate side, a method of mechanically peeling by inserting a blade into the interface between the support substrate and the temporary fixing material, and a method of softening the temporary fixing material with heat and peeling by sliding are also to be used.

[0071] The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited in any way by these examples. <Physical Properties and Evaluation of Polyimide Resin> The methods for measuring and evaluating each physical property of the polyimide films of the examples and comparative examples are shown below.

[0072] (1) Glass transition temperature (Tg) Using a differential scanning calorimeter "DSC 7000X" manufactured by Hitachi High-Tech Science Corporation, a polyimide film (test piece) was heated from 40°C to 220°C at a heating rate of 10°C / min, then cooled to 40°C at a cooling rate of 40°C / min, and then heated again to 250°C at a heating rate of 10°C / min. The glass transition temperature (Tg) was calculated from the DSC curve observed during the second heating process.

[0073] (2) 1% weight loss temperature (Td1%) A differential thermogravimetric thermogravimetric analyzer "NEXTA STA200RV" manufactured by Hitachi High-Tech Science Corporation was used. A polyimide film (test piece) was heated from 40°C to 150°C at a heating rate of 10°C / min, held at 150°C for 30 minutes to remove moisture, and then heated to 500°C. The temperature at which the weight decreased by 1% compared to the weight after holding at 150°C for 30 minutes was defined as the 1% weight loss temperature.

[0074] (3) Weight loss rate (%) after heating at 350°C for 1 hour A differential thermogravimetric analyzer "NEXTA STA200RV" manufactured by Hitachi High-Tech Science Corporation was used. A polyimide film (test piece) was heated from 40°C to 150°C at a heating rate of 10°C / min, held at 150°C for 30 minutes to remove moisture, and then heated to 350°C. The weight of the polyimide film at 350°C was used as the reference, and the weight loss rate was calculated from the amount of weight loss after holding at 350°C for 1 hour.

[0075] (4) Tensile modulus The tensile modulus of polyimide film (test specimen) was measured in accordance with JIS K7127:1999 using the "Strograph VG-1E" tensile testing machine manufactured by Toyo Seiki Co., Ltd.

[0076] (5) Solvent solubility (after post-bake) A silicon wafer spin-coated with polyimide varnish was placed on a hot plate and heated at 120°C for 20 minutes. Then, the solvent was evaporated in a hot air dryer at 250°C for 30 minutes to obtain a polyimide film, which was used as a test specimen. The polyimide film (test specimen) was immersed in γ-butyrolactone (GBL) at a concentration of 0.2% (w / w) at room temperature (25°C), stirred with a magnetic stirrer, and the solubility of the polyimide film in GBL was visually evaluated. The evaluation method is as follows: Excellent: Dissolved within 1 hour. Good: Did not dissolve within 1 hour, but dissolved within 24 hours. Average: Did not dissolve within 24 hours, but dissolved within 72 hours. Poor: Did not dissolve within 72 hours (insoluble).

[0077] (6) Polyimide films deposited on chemical-resistant silicon wafers were used as test specimens and immersed in propylene glycol monomethyl ether acetate (PGMEA) for 30 seconds at room temperature (25°C). The durability was evaluated by visually checking for the presence or absence of cracks on the surface of the polyimide film on the silicon wafer. The size of the test specimens was 10 mm x 20 mm, and the amount of butyl acetate was 50 mL. The evaluation method is as follows: Excellent: No cracks were observed. Poor: Cracks were observed.

[0078] (7) Solvent solubility (after annealing at 350°C for 60 minutes) A ​​polyimide film deposited on a silicon wafer was used as a test specimen and heated in a hot air dryer at 400°C for 60 minutes under a nitrogen atmosphere. After air cooling to room temperature (25°C), the test specimen was immersed in GBL solvent and stirred with a magnetic stirrer to evaluate solubility. The size of the test specimen was 10 mm × 20 mm, and the amount of GBL was 50 mL. The evaluation method is as follows: Excellent: Dissolved within 1 hour. Good: Did not dissolve within 1 hour, but dissolved within 24 hours. Average: Did not dissolve within 24 hours, but dissolved within 72 hours. Poor: Did not dissolve within 72 hours (insoluble).

[0079] [Example 1] In a 500 mL five-necked round-bottom flask equipped with a Dean-Stark apparatus fitted with a stainless steel crescent-shaped stirring blade, a nitrogen inlet tube, a condenser, a thermometer, and a glass end cap, 20.503 g (0.071 mol) of 1,5-bis(4-aminophenoxy)pentane (DA5MG; manufactured by Seika Co., Ltd.) (compound represented by formula (b1)) and 63.000 g of γ-butyrolactone (GBL; manufactured by Mitsubishi Chemical Corporation) were added. Under a nitrogen atmosphere, the system temperature was set to 70°C and the mixture was stirred at a rotation speed of 200 rpm to obtain a solution. To this solution, 22.074 g (0.071 mol) of dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride (H-BPDA; manufactured by Tokyo Chemical Industry Co., Ltd.) (compound represented by formula (a1)) and 28.000 g of GBL were added in one go. Then, 0.362 g of triethylamine (TEA; manufactured by Kanto Chemical Co., Ltd.) and 2.333 g of GBL were added as an imidation catalyst, and the solid content concentration during the reaction was set to 30 wt%. The reaction system was then heated with a mantle heater, and the temperature inside the reaction system was raised to 190°C over approximately 20 minutes. While collecting the components that were removed by distillation, the temperature inside the reaction system was maintained at 190°C and refluxed for 3 hours. After that, the temperature inside the reaction system was cooled to 50°C to obtain a polyimide varnish containing polyimide resin. Next, the obtained polyimide varnish was applied to a silicon wafer by spin coating, held at 120°C for 20 minutes on a hot plate, and then heated in a hot air dryer at 250°C for 30 minutes under an air atmosphere to evaporate the solvent and obtain a polyimide film. The physical properties and evaluation results of the film are shown in Table 1.

[0080] [Example 2] A solution containing polyimide resin was obtained in the same manner as in Example 1, except that DA5MG 7.108 g (0.025 mol) and 1,3-bis(3-aminophenoxy)benzene (TPE-M; manufactured by Seika Co., Ltd.) (compound represented by formula (b2)) 13.475 g (0.046 mol) were used as the diamine component instead of DA5MG 20.503 g (0.071 mol) as in Example 1. The types and blending ratios of the tetracarboxylic acid component and diamine component are shown in Table 1. A polyimide varnish containing polyimide resin was obtained in the same manner as in Example 1, and then a polyimide film was obtained. The physical properties and evaluation results of the polyimide film are shown in Table 1.

[0081] [Example 3] A solution containing polyimide resin was obtained in the same manner as in Example 2, except that cyclohexane-1,2,4,5-tetracarboxylic dianhydride (HPMDA; manufactured by Mitsubishi Gas Chemical Co., Ltd.) 18.697 g (0.083 mol) was used as the tetracarboxylic acid component instead of H-BPDA 22.074 g (0.071 mol) and DA5MG 8.357 g (0.029 mol) and TPE-M 15.843 g (0.054 mol) were used as the diamine components instead of DA5MG 7.108 g (0.025 mol) and TPE-M 13.475 g (0.046 mol). The types and mixing ratios of the tetracarboxylic acid component and diamine component are shown in Table 1. A polyimide varnish containing polyimide resin was obtained in the same manner as in Example 1, and then a polyimide film was obtained. The physical properties and evaluation results of the polyimide film are shown in Table 1.

[0082] [Comparative Example 1] A solution containing polyimide resin was obtained in the same manner as in Example 1, except that 20.603 g (0.071 mol) of TPE-M was used instead of 20.503 g (0.071 mol) of DA5MG as the diamine component. The types and blending ratios of the tetracarboxylic acid component and diamine component are shown in Table 1. A polyimide varnish containing polyimide resin was obtained in the same manner as in Example 1, and then a polyimide film was obtained. The physical properties and evaluation results of the polyimide film are shown in Table 1.

[0083]

[0084] As shown in Table 1, when comparing the polyimide resin of Comparative Example 1, which does not contain constituent units derived from DA5MG, with the polyimide resins of Examples 1 to 3, both the glass transition temperature and the 1% weight loss temperature are similar to those of the polyimide resin of Comparative Example 1 and the polyimide resins of Examples 1 and 2, but it is clear that it has superior chemical resistance. Furthermore, the polyimide resin of Example 3 had higher glass transition temperature and 1% weight loss temperature compared to the polyimide resin of Comparative Example 1. This is thought to be due to the fact that in Example 3, HPMDA, which has higher rigidity than H-BPDA, was used as the tetracarboxylic acid component, and DA5MG, which has a linear alkyl chain, was used as the diamine component in addition to TPE-M. In addition, compared to the polyimide film (polyimide resin) of Comparative Example 1, the polyimide films (polyimide resins) of Examples 1 to 3 all have lower tensile modulus and low modulus, so good adhesion can be expected. Furthermore, the polyimide films (polyimide resins) of the examples had excellent solubility in GBL. Because it is soluble in low-water-absorbent solvents such as GBL, the polyimide film of the present invention can be processed using low-water-absorbent solvents, making it less susceptible to the effects of humidity and moisture during peeling. Furthermore, the polyimide resin of the example exhibits excellent chemical resistance. As described above, the polyimide resin of the present invention can be suitably used as a temporary fixing material, and the temporary fixing material composition containing the polyimide resin has the above-mentioned excellent properties.

Claims

1. A polyimide resin having constituent unit A derived from a tetracarboxylic dianhydride and constituent unit B derived from a diamine, wherein constituent unit A includes constituent unit (A1') selected from the group consisting of compounds represented by the following formula (a1) and compounds represented by the following formula (a2), A polyimide resin containing a constituent unit (B1') whose constituent unit B is derived from a compound represented by the following formula (B1). (In formula (B1), X 1 Each of these is independently a divalent hydrocarbon group having 1 to 7 carbon atoms, -O-, -S-, -SO2-, or -CO-, and n is an integer from 4 to 10.

2. The polyimide resin according to claim 1, wherein the constituent unit B further comprises a constituent unit (B2') derived from a compound represented by the following formula (B2), and the ratio of constituent unit (B2') in constituent unit B is greater than 0 mol% and less than or equal to 70 mol%. (In the formula, Z is independently -O-, -COO-, -OCO-, -C(CH3)2-, or -C(CF3)2-.) 3. The polyimide resin according to claim 2, wherein the compound represented by formula (B1) is the compound represented by the following formula (b1), and the compound represented by formula (B2) is the compound represented by the following formula (b2).

4. A polyimide varnish containing the polyimide resin and organic solvent according to any one of claims 1 to 3.

5. A polyimide film comprising the polyimide resin described in any one of claims 1 to 3.

6. A temporary fixing material composition comprising a polyimide resin according to any one of claims 1 to 3.

7. A method for thinning a semiconductor wafer, comprising: step 1 of applying the temporary fixing material composition according to claim 6 to a semiconductor wafer or a support substrate to form an adhesive layer for temporary fixing; step 2 of temporarily fixing the support substrate to the semiconductor wafer via the adhesive layer; step 3 of grinding the back surface of the semiconductor wafer while the support substrate is temporarily fixed to the semiconductor wafer via the adhesive layer; and step 4 of peeling off the support substrate.

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