Polyamic acid varnish, and method for producing semiconductor device

Abstract

To provide a varnish composed of a polyamide acid containing at least a specific amount of aliphatic diamine, prepared using NMP substitute solvents.SOLUTION: A polyamic acid varnish contains a polyamide acid and a solvent. The polyamide acid is a polyadduct of a tetracarboxylic dianhydride and a diamine. The diamine includes an aliphatic diamine (Aa) with an amino group bound to an aliphatic group, where a content of the aliphatic diamine (Aa) is 13.5 mass% or more relative to a total amount of a monomer composed of the tetracarboxylic acid dianhydride and the diamine. The solvent includes a solvent with an amide skeleton (excluding N-methyl-2-pyrrolidone) or a solvent with a sulfoxide skeleton.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a polyamic acid varnish and a method for producing a semiconductor device. [Background technology]

[0002] Polyimide resin is a material with excellent durability and heat resistance, and is widely used in electronic material applications. For example, the replacement of glass substrates used in image display devices such as OLED displays of liquid crystal displays with plastic substrates is being considered. Polyimide resins are sometimes used as materials for such plastic substrates. Polyimide resins are also used in surface protective films and interlayer insulating films of semiconductor elements.

[0003] Known methods for producing molded articles of these polyimide resins include a method in which a varnish containing a polyamic acid precursor is applied onto a substrate, followed by heating to dry and imidize the varnish, and a method in which a varnish containing polyimide is applied onto a substrate and then dried, etc. As a solvent for these varnishes, N-methyl-2-pyrrolidone (NMP) is usually used.

[0004] However, NMP is known to be one of the substances of high concern due to its harmful effects, and there is a demand for the use of alternative solvents.

[0005] As an alternative solvent to NMP, γ-butyrolactone (γ-BL) is often used. For example, Patent Document 1 discloses a polyimide varnish containing γ-BL and a polyimide resin containing a structural unit (A1) derived from a tetracarboxylic dianhydride having a norbornane skeleton and a structural unit (B1) derived from a compound represented by formula (b1).

[0006] Patent Document 2 discloses a polyamic acid varnish containing a polyamic acid, a solvent represented by formula (1), and a solvent containing a nitrogen atom or a sulfur atom other than the solvent represented by formula (1). In a synthesis example, a polyamic acid varnish is prepared which contains ethoxy-N,N-dimethylpropion or 1,3-dimethyl-2-imidazolidinone as the solvent represented by formula (1) and dimethyl sulfoxide as the solvent other than the solvent represented by formula (1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2022 / 091814 [Patent Document 2] JP 2020-2284 A Summary of the Invention [Problem to be solved by the invention]

[0008] The polyamic acid varnish as described above is prepared by polyaddition reaction of tetracarboxylic dianhydride and diamine in a solvent. However, the nucleophilicity of the amino group of an aliphatic diamine in which the nitrogen atom of the amino group is bonded to an aliphatic group (including an alicyclic group) is higher than the nucleophilicity of the amino group of an aromatic diamine in which the nitrogen atom of the amino group is bonded to an aromatic ring. When attempting to prepare a polyamic acid containing a predetermined amount or more of such an aliphatic diamine in γ-BL, there was a problem that the polymerization reaction did not proceed and polyamic acid with the desired polymerization degree could not be obtained.

[0009] The present invention has been made in view of the above problems, and an object of the present invention is to provide a varnish containing a polyamic acid containing a predetermined amount or more of an aliphatic diamine, which is prepared using an alternative solvent to NMP, and a method for producing a semiconductor device using the same. [Means for solving the problem]

[0010] The above problem can be solved by the following configuration.

[0011] [1] A polyamic acid varnish comprising a polyamic acid and a solvent, the polyamic acid being a polyaddition product of a tetracarboxylic dianhydride and a diamine, the diamine comprising an aliphatic diamine (Aa) having an amino group bonded to an aliphatic group, the content of the aliphatic diamine (Aa) being 5.0 mol % or more based on the total amount of monomers consisting of the tetracarboxylic dianhydride and the diamine, and the solvent comprising a solvent having an amide skeleton (excluding N-methyl-2-pyrrolidone) or a solvent having a sulfoxide skeleton. [2] The polyamic acid varnish according to [1], wherein the solvent includes a solvent having the amide skeleton. [3] The polyamic acid varnish according to [2], wherein the solvent having an amide skeleton has a cyclic structure. [4] The polyamic acid varnish according to any one of [1] to [3], wherein the solvent having an amide skeleton contains 1,3-dimethyl-2-imidazolidinone. [5] The polyamic acid varnish according to any one of [1] to [4], wherein a total content of the solvent having an amide skeleton and the solvent having a sulfoxide skeleton is 60 mass % or more based on the total amount of the solvents. [6] The polyamic acid varnish according to any one of [1] to [5], wherein the aliphatic diamine (Aa) includes at least one of an aliphatic diamine represented by formula (1) and an aliphatic diamine represented by formula (2): [ka] (In formula (1), R 1 is an aliphatic chain having a main chain composed of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is 21 to 500. [ka] (In formula (2), R 2 is an aliphatic chain having a main chain composed of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is 5 to 20. [7] The polyamic acid varnish according to any one of [1] to [6], wherein the monomer contains at least one of an aromatic tetracarboxylic dianhydride represented by formula (3) and an aromatic diamine represented by formula (4). [ka] [ka] (R in Eq. (3) 2 and R in formula (4) 3 are divalent groups having a main chain composed of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is 2 to 100. [8] The polyamic acid varnish according to [7], wherein the aromatic tetracarboxylic dianhydride represented by the formula (3) includes an aromatic tetracarboxylic dianhydride represented by the formula (3-1), and the aromatic diamine represented by the formula (4) includes an aromatic diamine represented by the formula (4-1). [ka] (In formula (3-1), Y is an oxygen atom, a methylene group, or -CR a R b (R a and R b represents a divalent group selected from the group consisting of substituted or unsubstituted alkyl groups each having 1 to 3 carbon atoms, m represents an integer of 0 or 1, R 5 and R 6 each represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms, e and f each represent an integer of 0 to 3. [ka] (In formula (4-1), Z is an oxygen atom, a methylene group, or -CR c R d (R c and R drepresents a divalent group selected from the group consisting of substituted or unsubstituted alkyl groups each having 1 to 3 carbon atoms, n represents an integer of 0 or 1, R 7 and R 8 each represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms, g and h each represent an integer of 0 to 3. [9] The polyamic acid varnish according to [8], wherein the total content of the aromatic tetracarboxylic dianhydride represented by the formula (3-1) and the aromatic diamine represented by the formula (4-1) is 60 to 90 mol % based on the total amount of the monomers.

[10] A method for manufacturing a semiconductor device, comprising: a step of applying the polyamic acid varnish according to any one of [1] to [9] onto a substrate, followed by imidization to form a resin layer; and a step of heating the resin layer to a temperature equal to or higher than its melting temperature, and bonding a supporting substrate to the resin layer. Effect of the Invention

[0012] According to the present invention, it is possible to provide a varnish containing a polyamic acid containing a predetermined amount or more of an aliphatic diamine, which is prepared using an alternative solvent to NMP, and a method for producing a semiconductor device using the same. [Brief description of the drawings]

[0013] [Figure 1] 1A to 1F are schematic diagrams showing a part of a method for manufacturing a semiconductor device according to one embodiment of the present invention. [Diagram 2] 2A to 2C are schematic diagrams showing another part of the method for manufacturing a semiconductor device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As described above, even if the above aliphatic diamine is reacted in a solvent containing a predetermined amount or more of γ-BL, the reaction is inhibited and polyamic acid having a predetermined degree of polymerization cannot be obtained in some cases.

[0015] The reason for this is not clear, but is thought to be as follows. As mentioned above, aliphatic diamines, in which the nitrogen atom of the amino group is bonded to an aliphatic group, are more basic than aromatic diamines, in which the nitrogen atom of the amino group is bonded to an aromatic ring. Therefore, the amino group of the aliphatic diamine easily attacks a solvent with an ester skeleton, such as γ-BL, and decomposes the solvent molecule. As a result, it is assumed that the aliphatic diamine is less likely to be consumed in the polymerization reaction, which is where it should be consumed, and the polymerization reaction is inhibited. In addition, the amino group of the aliphatic diamine may attack the carboxyl group of the amic acid oligomer to produce a salt. The salt produced is poorly soluble in γ-BL, making it difficult for the reaction to proceed further.

[0016] In contrast, in the present invention, a solvent having an amide skeleton (-C(=O)-N-) or a solvent having a sulfoxide skeleton (-S(=O)-) other than N-methyl-2-pyrrolidone is used as the solvent. Nucleophilic attack by the amino group of the aliphatic diamine is unlikely to occur against the above-mentioned solvent having an amide skeleton or a solvent having a sulfoxide skeleton. As a result, the aliphatic diamine can be consumed in the original polymerization reaction, so that the polymerization reaction is unlikely to be inhibited, and a polyamic acid having a predetermined degree of polymerization can be obtained. In addition, even if the amino group of the aliphatic diamine attacks the carboxyl group of the amic acid oligomer to generate a salt, the generated salt is easily soluble in these solvents, and therefore, it is believed that the reaction proceeds.

[0017] Such polyamic acids containing a predetermined amount or more of aliphatic diamines can provide polyimides with appropriate flexibility, which are suitable for various adhesives, for example, temporary fixing adhesives for bonding semiconductor wafers and supporting substrates in the manufacturing process of semiconductor devices.

[0018] Hereinafter, a polyamic acid varnish according to one embodiment of the present invention will be described.

[0019] 1. Polyamic acid varnish The polyamic acid varnish according to this embodiment contains a polyamic acid and a solvent.

[0020] 1-1. Polyamic acid Polyamic acid is a polyaddition product of tetracarboxylic dianhydride and diamine. The monomer consisting of tetracarboxylic dianhydride and diamine contains at least aliphatic monomer (A). The aliphatic monomer (A) can impart appropriate flexibility to the obtained polyimide.

[0021] (Aliphatic Monomer (A)) The aliphatic monomer (A) includes at least an aliphatic diamine (Aa).

[0022] The aliphatic diamine (Aa) is a diamine having an amino group bonded to an aliphatic group, that is, a diamine in which the nitrogen atom of the amino group is directly bonded to the carbon atom of the aliphatic group. The aliphatic group may be a chain-like aliphatic group or a cyclic aliphatic group (alicyclic group), but is preferably a chain-like aliphatic group (aliphatic chain). The aliphatic chain is an aliphatic chain having a main chain consisting of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is preferably 3 or more, more preferably 5 or more. The upper limit of the total number of atoms can be, for example, 500 or less. The aliphatic chain is preferably a (poly)alkyleneoxy group or an alkylene group. When such a polyimide is used for thermocompression bonding of two adherends, the melt flowability of the polyimide can be increased, and the two adherends can be bonded well.

[0023] The content of the aliphatic diamine (Aa) is 5.0 mol% or more based on the total amount of monomers consisting of tetracarboxylic dianhydride and diamine constituting the polyamic acid. When the content of the aliphatic diamine (Aa) is 5.0 mol% or more, the flexibility of the obtained polyimide can be increased, for example, the melt flowability can be improved. When two adherends are thermocompressed with a resin layer containing such a polyimide, the melt flowability of the polyimide can be increased, so that the resin layer can be easily uniformly spread over the entire bonding surface, and good adhesion can be achieved. From the same viewpoint, the content of the aliphatic diamine (Aa) is preferably 10.0 mol% or more, more preferably 12.0 mol% or more. The upper limit of the content of the aliphatic diamine (Aa) is not particularly limited, but from the viewpoint of further increasing the heat resistance of the polyimide by setting the content of the aromatic monomer (B) described later to a predetermined value or more, it is preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol%.

[0024] The aliphatic diamine (Aa) preferably contains at least one of an aliphatic diamine represented by formula (1) and an aliphatic diamine represented by formula (2). [ka]

[0025] In formula (1), R 1 is an aliphatic chain having a main chain composed of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is 21 to 500, preferably 40 to 400, more preferably 40 to 300, and further preferably 50 to 100. 1 The main chain in the formula (1) is an aliphatic chain that connects the two amino groups at the molecular ends, and is composed of atoms other than those that make up the side chains. The aliphatic diamine represented by formula (1) has a long main chain, which makes it easier to increase the melt fluidity.

[0026] Examples of the main chain consisting of one or more atoms of C, N, and O include a main chain having a structure derived from a polyalkylene polyamine such as diethylenetriamine, triethylenetetramine, or tetraethylenepentamine; an alkylene main chain; a main chain having an alkyl ether structure; a main chain having a polyalkylene carbonate structure; and a main chain containing an alkyleneoxy group or a polyalkyleneoxy group.

[0027] In the main chain containing an alkyleneoxy group or a polyalkyleneoxy group, the polyalkyleneoxy group is a divalent linking group containing alkyleneoxy as a repeating unit, and is a repeating unit of ethyleneoxy units such as "-(CH2CH2O) n -" and "-(CH2-CH(-CH3)O)" which has propyleneoxy units as repeating units. m -" (n and m are the number of repetitions) are some examples.

[0028] The number of carbon atoms in the alkylene portion of the alkyleneoxy group and the alkylene portion of the alkyleneoxy unit constituting the polyalkyleneoxy group is preferably 2 to 10. Examples of the alkylene group constituting the alkyleneoxy group include an ethylene group, a propylene group, and a butylene group.

[0029] Among them, the main chain preferably contains an ether bond. That is, the main chain preferably contains an alkyleneoxy group or a polyalkyleneoxy group, or an alkyl ether structure. The ether bond is easily decomposed by irradiation with a laser beam, and therefore the peelability by LLO can be improved.

[0030] R 1 The aliphatic chain represented by may further have a side chain consisting of one or more atoms of C, N, H, and O. The side chain is a monovalent group connected to an atom constituting the main chain. The total number of atoms constituting the side chain is preferably 10 or less. Examples of such side chains include alkyl groups such as methyl groups.

[0031] Examples of the aliphatic diamine represented by formula (1) include (poly)alkyleneoxydiamines having 20 to 70 carbon atoms, preferably (poly)alkyleneoxydiamines represented by formula (1-1). [ka]

[0032] In formula (1-1), p, q, and r each independently represent an integer of 0 to 12. However, 3p+q×(n+1)+3r+2 is preferably 21 to 500, preferably 40 to 400, and more preferably 50 to 100. Since such an aliphatic diamine contains a long-chain alkyleneoxy group, the resulting polyimide has high flexibility. In addition, an alkylene group having a branched structure is easily decomposed by heat generated by absorption of laser light, so that the peelability by LLO can be further improved. Examples of the aliphatic diamine represented by formula (1-1) include RT1000 and ED900 (both manufactured by HUNTSMAN, polyetheramine), etc.

[0033] [ka]

[0034] In formula (2), R 2 is an aliphatic chain having a main chain composed of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is 5 to 20, preferably 5 to 18, more preferably 8 to 14, and further preferably 8 to 12. 2 The main chain in the formula (2) is, as mentioned above, an aliphatic chain that connects two amino groups at the molecular ends, and is a chain consisting of atoms other than those that make up the side chain. The aliphatic diamine represented by formula (2) has a short main chain, which can reduce the decrease in heat resistance.

[0035] The main chain consisting of one or more atoms of C, N, and O may be the same as the main chain consisting of one or more atoms of C, N, and O in formula (1).

[0036] R 2The aliphatic chain represented by the following formula may further have a side chain consisting of one or more atoms of C, N, H and O, similarly to the above formula (1).

[0037] Examples of the aliphatic diamine represented by formula (2) include linear alkylene diamines having 4 to 12 carbon atoms and linear (poly)alkyleneoxy diamines having 6 to 12 carbon atoms. Examples of linear (poly)alkyleneoxy diamines having 4 to 12 carbon atoms include 1,8-diamino-3,6-dioxaoctane, 4,9-dioxane-1,12-dodecanediamine, 1,13-diamino-4,7,10-trioxatridecane, etc. Examples of linear alkylene diamines having 6 to 12 carbon atoms, preferably 6 to 10 carbon atoms, include 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, and 1,12-diaminododecane.

[0038] For example, from the viewpoint of further increasing the melt fluidity, the aliphatic diamine (Aa) preferably contains an aliphatic diamine represented by formula (1), and more preferably contains both an aliphatic diamine represented by formula (1) and an aliphatic diamine represented by formula (2). When the aliphatic monomer (A) contains both an aliphatic diamine represented by formula (1) and an aliphatic diamine represented by formula (2), it is preferable that the main chain of the aliphatic diamine represented by formula (1) contains an ether bond, and the main chain of the aliphatic diamine represented by formula (2) does not contain an ether bond. When the main chain of the aliphatic diamine represented by formula (2) does not contain an ether bond, the main chain is preferably an alkylene chain, and more preferably a linear alkylene chain having no branched structure. This can prevent the melt fluidity from becoming excessively high, and can further ensure heat resistance.

[0039] The ratio Aa1 / Aa2 of the content Aa1 of the aliphatic diamine represented by formula (1) to the content Aa2 of the aliphatic diamine represented by formula (2) is preferably 0.8 to 1.8 (mass ratio), more preferably 1.0 to 1.6 (mass ratio), and further preferably 1.3 to 1.5 (mass ratio). When Aa1 / Aa2 is equal to or more than the lower limit, the melt fluidity is more likely to be increased, and when Aa1 / Aa2 is equal to or less than the upper limit, the decrease in heat resistance is more likely to be suppressed.

[0040] The aliphatic monomer (A) may further include a tetracarboxylic dianhydride (Ab) having an aliphatic group. Examples of such a tetracarboxylic dianhydride (Ab) include tetracarboxylic dianhydrides having an aliphatic chain and tetracarboxylic dianhydrides having an alicyclic group.

[0041] The content of the aliphatic monomer (A) is preferably 5.0 mol% or more based on the total amount of monomers from the viewpoint of achieving both heat resistance and sufficient melt fluidity at the lamination temperature. When the content of the aliphatic monomer (A) is 5.0 mol% or more, the melt fluidity of the polyimide is more likely to be increased. The upper limit of the content of the aliphatic monomer (B) is not particularly limited, but is preferably 30.0 mol% or less from the viewpoint of preventing the heat resistance of the polyimide from being impaired.

[0042] (Aromatic Monomer (B)) The monomers constituting the polyamic acid preferably further contain an aromatic monomer (B). The aromatic monomer (B) can impart heat resistance to the resulting polyimide. In addition, since aromatic rings easily absorb laser light, when the polyimide contains an ether bond, the ether bond is easily decomposed by heat generated by absorbing the laser light, and the peelability by LLO can be improved. The aromatic monomer (B) may be a tetracarboxylic dianhydride or a diamine.

[0043] That is, the aromatic monomer (B) preferably contains at least one of an aromatic tetracarboxylic dianhydride represented by formula (3) and an aromatic diamine represented by formula (4). [ka] [ka]

[0044] R in Equation (3) 3 and R in formula (4) 4 are divalent groups having a main chain composed of one or more atoms of C, N, or O.

[0045] The divalent group may or may not contain an aromatic ring, but from the viewpoint of further improving heat resistance, it is preferable that the divalent group contains an aromatic ring. The total number of atoms constituting the main chain is 2 to 100, preferably 4 to 50, and more preferably 6 to 30. When the main chain contains an aromatic ring, the atoms constituting the ring (for example, in the case of a benzene ring, the atoms constituting the ring are 6 carbon atoms) are also counted in the atoms constituting the main chain. The divalent group may further have a side chain consisting of one or more atoms of C, N, H, and O, and the total number of atoms constituting the side chain is 10 or less.

[0046] The aromatic tetracarboxylic dianhydride represented by formula (3) preferably contains an aromatic tetracarboxylic dianhydride represented by formula (3-1): The flexibility of the resulting polyimide film can be increased while maintaining the heat resistance. [ka]

[0047] In formula (3-1), Y is an oxygen atom, a methylene group, or -CR a R b (R a and R b each represents a divalent group selected from the group consisting of a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms; preferably -CRa R b and more preferably -C(CH3)2. Each m represents an integer of 0 or 1, and is preferably 0.

[0048] R 5 and R 6 each represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms; preferably a methyl group or a methoxy group. e and f each represent an integer of 0 to 3, preferably 0 or 1.

[0049] Examples of the aromatic tetracarboxylic dianhydride represented by formula (3-1) include 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride) (pBPADA).

[0050] The aromatic diamine represented by formula (4) preferably contains an aromatic diamine represented by formula (4-1): The flexibility of the resulting polyimide film can be increased while maintaining the heat resistance. [ka]

[0051] Z and R in formula (4-1) 7 , R 8 , n, g and h represent Y, m, R in formula (3-1). 5 , R 6 , e and f, respectively.

[0052] Examples of the aromatic diamine represented by formula (4-1) include bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane.

[0053] The total amount of the aromatic tetracarboxylic dianhydride represented by formula (3-1) and the aromatic diamine represented by formula (4-1) is not particularly limited, but is preferably 60 to 90 mol% based on the total amount of monomers. If the total amount is 60 mol% or more, the heat resistance is further increased and the laser light is more easily absorbed, so that the peelability by LLO, for example, is more easily improved. From the same viewpoint, the total amount is more preferably 70 to 85 mol% based on the total amount of monomers.

[0054] The aromatic monomer (B) may further contain other aromatic monomers as long as the effects of the present invention are not impaired. The other aromatic monomers may be, for example, other aromatic tetracarboxylic dianhydrides. Examples of the other aromatic tetracarboxylic dianhydrides include: Aromatic tetracarboxylic dianhydrides having a biphenyl skeleton, such as 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA); Aromatic tetracarboxylic acid dianhydrides having a diphenyl ether skeleton not corresponding to formula (3-1), such as 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 4,4'-oxydiphthalic anhydride (ODPA), 3,4'-oxydiphthalic anhydride, and 3,3'-oxydiphthalic anhydride; Aromatic tetracarboxylic dianhydrides having a hexafluoroisopropylidene skeleton, such as 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride (6FDA); and Aromatic tetracarboxylic dianhydrides with a fluorene skeleton, such as 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF) These aromatic tetracarboxylic dianhydrides have a suitable degree of rigidity, and therefore the heat resistance (T d5 ) is easy to increase.

[0055] (Common matters) The molecular end of the polyamic acid may be either an acid anhydride group or an amino group. From the viewpoint of increasing the solubility of the polyimide film, it is preferable that the proportion of the molecular end being an acid anhydride group is greater than the proportion of the molecular end being an amino group. In order to increase the proportion of the molecular end being an acid anhydride group, the tetracarboxylic dianhydride component (a moles) to be reacted may be greater than the diamine component (b moles). Specifically, the molar ratio of the diamine (b moles) and the tetracarboxylic dianhydride (a moles) constituting the polyamic acid is not particularly limited, but is preferably b / a=0.90 to 0.999, and may be 0.90 to 0.95. When b / a is 0.999 or less, the molecular end of the obtained polyimide is easily converted to an acid anhydride group, so that the solubility of the polyimide film is easily obtained. b / a can be specified as the charge ratio of the tetracarboxylic dianhydride component (a moles) and the diamine component (b moles) to be reacted.

[0056] The E-type viscosity of the polyamic acid varnish is preferably 1,000 to 100,000 mPas, more preferably 5,000 to 50,000 mPas, from the viewpoint of facilitating film formation and stirring. The E-type viscosity of the polyamic acid varnish can be a value measured 240 seconds after the end of preheating, using a cone rotor (3°×R9.7) at a rotation speed at which the torque falls within 0 to 80% under conditions of 25°C, after 0.15 mL of polyamic acid varnish prepared so that the resin solid content is 1 to 50% is placed in an E-type viscometer (Toki Sangyo Co., Ltd., VISCOMETER TV-25), and preheating at 25°C for 120 seconds.

[0057] From the viewpoint of facilitating film formation, the intrinsic viscosity η of the polyamic acid varnish is preferably 0.35 to 2.00 dL / g, more preferably 0.40 to 1.50 dL / g. The intrinsic viscosity (η) of the polyamic acid varnish is the average value of three measurements at 25°C using an Ubbelohde viscosity tube when the polyamic acid varnish is dissolved in N-methyl-2-pyrrolidone (NMP) to a concentration of 0.5 g / dL. When the intrinsic viscosity (η) of the polyamic acid varnish is 0.35 dL / g or more, the resulting polyimide film is less likely to become brittle, and is flexible and easily deformed, making it suitable for lamination. When the intrinsic viscosity (η) of the polyamic acid varnish is 2.00 dL / g or less, the polyamic acid varnish can be more easily turned into a film while maintaining a certain level of solid content concentration, thereby improving the handleability.

[0058] The intrinsic viscosity (η) of the polyamic acid varnish can be adjusted by the type of solvent used in preparing the polyamic acid varnish. For example, by increasing the content of a solvent having an amide skeleton, polymerization is facilitated, and the intrinsic viscosity of the polyamic acid varnish is likely to increase.

[0059] 1-2.Solvent The solvent includes a solvent having an amide skeleton or a solvent having a sulfoxide skeleton, provided that the amide solvent is not N-methyl-2-pyrrolidone.

[0060] The solvent having an amide skeleton is a solvent having an amide skeleton in the molecule. The solvent having a sulfoxide skeleton is a solvent having a sulfoxide skeleton in the molecule. These solvents may have a chain structure or a cyclic structure. From the viewpoint of further increasing the solubility of the monomer or the above-mentioned salt, it is preferable that the solvent having an amide skeleton or the solvent having a sulfoxide skeleton has a cyclic structure.

[0061] Examples of the solvent having an amide skeleton include solvents having a cyclic amide skeleton such as 1,3-dimethyl-2-imidazolidinone and 2-imidazolidinone; and solvents having a chain amide skeleton such as 3-methoxy-N,N-dimethylpropanamide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dipropylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dipropylacetamide, 1,3-dimethylurea, 1,3-diethylurea, tetramethylurea, tetraethylurea, propyleneurea, and N,N'-dimethylpropyleneurea. Among them, 1,3-dimethyl-2-imidazolidinone is preferred from the viewpoint of high solubility of monomers and salts and easy production of polyamic acid having a predetermined degree of polymerization.

[0062] Examples of the solvent having a sulfoxide skeleton include dimethyl sulfoxide, diethyl sulfoxide, dibutyl sulfoxide, diphenyl sulfoxide, and sulfolane.

[0063] The total content of the solvent having an amide skeleton or the solvent having a sulfoxide skeleton is preferably 60% by mass or more based on the total solvent. When the content of the solvent having an amide skeleton or the solvent having a sulfoxide skeleton is 60% by mass or more, the monomer and the generated salt are more easily dissolved, so that the reaction can be more easily continued. From the same viewpoint, the content of these solvents is more preferably 70% by mass or more, and further preferably 90% by mass or more. The upper limit of the total content of the above solvents is not particularly limited, but may be 100% by mass or less based on the total solvent, and when combined with other solvents, it may be, for example, 90% by mass or less based on the total solvent.

[0064] The solvent may further include other solvents other than those described above. The other solvents are not particularly limited as long as they can dissolve the diamine component and the tetracarboxylic dianhydride component described above, and examples of the other solvents include aprotic polar solvents, aromatic hydrocarbon solvents, and alcohol solvents.

[0065] Examples of aprotic polar solvents include N-methyl-2-pyrrolidone, hexamethylphosphoramide, and epsilon-caprolactone; ether solvents such as 2-methoxyethanol, 2-ethoxyethanol, 2-(methoxymethoxy)ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, and tetrahydrofuran. Ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol, polypropylene glycol, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, anisole, propylene glycol monomethyl ether acetate; and ketone solvents such as cyclohexanone.

[0066] Examples of aromatic hydrocarbon solvents include toluene, o-xylene, m-xylene, p-xylene and mixed xylenes, 1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, chlorobenzene, orthochlorobenzene, and the like.

[0067] Examples of the alcohol-based solvent include methanol, ethanol, 1-propanol, 2-propanol, tert-butyl alcohol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, and diacetone alcohol.

[0068] When the above solvent contains a solvent having a sulfoxide skeleton, the storage stability of the polyamic acid varnish may be somewhat poor. In such a case, the storage stability can be further improved by combining the solvent with a ketone solvent or an ether solvent.

[0069] From the viewpoint of reducing the content of substances of very high concern, it is preferable that the solvent contained in the polyamic acid varnish is substantially free of N-methyl-2-pyrrolidone, which means that the content of N-methyl-2-pyrrolidone in the entire solvent is 10% by mass or less, and preferably 0% by mass.

[0070] The total amount of the solvent is preferably 50 to 95% by mass, and more preferably 70 to 90% by mass, based on the polyamic acid varnish.

[0071] From the viewpoint of improving coatability, the content of polyamic acid in the polyamic acid varnish is preferably from 5 to 50 mass %, more preferably from 10 to 40 mass %, and further preferably from 15 to 35 mass %.

[0072] 1-3. Physical properties of polyamic acid varnish The polyamic acid varnish preferably satisfies the following physical properties from the viewpoint of obtaining good lamination properties when used, for example, as a temporary fixing adhesive.

[0073] i) Glass transition temperature (Tg) The Tg of the polyimide obtained by imidizing the polyamic acid varnish is preferably 80 to 150°C. When the Tg of the polyimide is 80°C or higher, the melt viscosity is not too low, so that, for example, when two adherends are bonded together, it is possible to further suppress the extrusion from the coated surface. When the Tg of the polyimide is 150°C or lower, the drying temperature for removing the solvent can be lowered, so that the drying property can be further improved. From the same viewpoint, the Tg of the obtained polyimide is more preferably 80 to 140°C, and further preferably 100 to 130°C.

[0074] The Tg of a polyimide can be measured by the following method. A polyamic acid varnish is applied onto a glass plate, heated from 50°C to the heating temperature at a rate of 5°C / min in the atmosphere, and held at the heating temperature for 30 minutes to obtain a polyimide film. The obtained polyimide film is cut into a size of 5 mm in width and 22 mm in length. The Tg of the cut film is measured using a thermal analyzer (e.g., Shimadzu Corporation's TMA-50). Specifically, the measurement is performed in an air atmosphere, at a heating rate of 5°C / min, and in a tensile mode (100 mN), to obtain a TMA curve. In the obtained TMA curve, the curves before and after the inflection point of the TMA curve due to the glass transition are extrapolated to obtain the glass transition temperature (Tg).

[0075] The heating temperature is set to a temperature higher than the glass transition temperature Tg of the film, which is measured in advance. The heating temperature is preferably (Tg+10) to (Tg+30)°C. The lower limit of the heating temperature can be 180°C or higher from the viewpoint of volatilizing the solvent, and the upper limit of the heating temperature can be 300°C or lower from the viewpoint of making it difficult to suppress thermal decomposition of the polyimide film. That is, the heating temperature is preferably 180 to 300°C and (Tg+10) to (Tg+30)°C.

[0076] The Tg of the polyimide can be adjusted, for example, by the content of the aliphatic monomer (A) or the type of aromatic monomer (B). For example, increasing the content of the aliphatic monomer (A) tends to lower the Tg of the polyimide. Increasing the content of the aromatic tetracarboxylic dianhydride represented by formula (3-1) or the aromatic diamine represented by formula (4-1) as the aromatic monomer (B) tends to raise the Tg of the polyimide.

[0077] ii) Melting temperature The melting temperature of the polyimide obtained by imidizing the polyamic acid varnish is preferably 160 to 220° C. If the melting temperature is 220° C. or less, the polyimide exhibits melt fluidity at a relatively low temperature, and therefore, for example, when two adherends are thermocompression-bonded to each other via the polyimide film, the polyimide film can be more uniformly spread over the entire bonding surface. From the same viewpoint, the melting temperature of the polyimide is more preferably 170 to 220° C.

[0078] iii) Complex viscosity The melt viscosity (complex viscosity) at the melting temperature of the polyimide obtained by imidizing the polyamic acid varnish is preferably 40000 mPa·s or less. When the complex viscosity is 40000 mPa·s or less, the viscosity when heated to the melting temperature or higher is appropriately low, so that, for example, when two adherends are thermocompressed with a resin layer containing polyimide, the resin layer can be more uniformly spread over the entire bonding surface. In addition, the lower limit of the complex viscosity is not particularly limited, but can be, for example, 1000 mPa·s or more from the viewpoint of preventing the polyimide from protruding from the coating surface. From the same viewpoint, the complex viscosity of the polyimide obtained by imidizing the polyamic acid varnish is preferably 1000 to 30000 mPa·s, more preferably 1000 to 20000 mPa·s, even more preferably 1000 to 15000 mPa·s, and even more preferably 2000 to 10000 mPa·s.

[0079] The melting temperature and the complex viscosity can be measured by melt viscoelasticity measurement. First, the polyimide film prepared for the measurement of Tg in i) above is cut into a number of pieces each having a diameter of 15 to 25 mm, and these are stacked to prepare a sample having a thickness of 0.5 to 2 mm. Next, the prepared sample is set in a TA Instruments ARES-G2 rheometer, and heated to a predetermined temperature at a frequency of 1 Hz and a heating rate of 3°C / min, and the melt viscoelasticity is measured. In the obtained measurement results, the point at which the storage modulus and the loss modulus become equal (the temperature at which tan δ=1) when focusing on the temperature range higher than the glass transition temperature is the melting point, and the temperature at which the melting point is reached is defined as the melting temperature. The melt viscosity at the melting temperature (melting point) is defined as the complex viscosity.

[0080] The melting temperature and complex viscosity of the polyimide can be adjusted, for example, by the content and type of the aliphatic monomer (A) and the type of the aromatic monomer (B). For example, by increasing the content of the aliphatic monomer (A), the melting temperature and complex viscosity of the polyimide tend to be lower. In addition, by using a flexible monomer such as the aromatic tetracarboxylic dianhydride represented by formula (3-1) as the aromatic monomer (B) instead of a rigid monomer such as BPDA, the melting temperature and complex viscosity of the polyimide tend to be lower.

[0081] Moreover, it is preferable that the polyamic acid varnish has high heat resistance to withstand high-temperature processes and good solubility in solvents.

[0082] iv) 5% weight loss temperature (T d5 ) The 5% weight loss temperature (T d5 From the same viewpoint as above, the T of polyimide is preferably 300° C. or higher, and more preferably 400° C. or higher. d5 The upper limit is not particularly limited, but may be, for example, 600°C.

[0083] Polyimide T d5 For example, when the content of the aromatic tetracarboxylic dianhydride represented by formula (3-1) or the aromatic diamine represented by formula (4-1) as the aromatic monomer (B) is increased, the T d5 is likely to be high.

[0084] v) Solubility The polyimide obtained by imidizing the polyamic acid varnish is preferably highly soluble in a solvent, for example, from the viewpoint of dissolving in a solvent and facilitating peeling when used as an adhesive. Specifically, the polyimide film obtained by imidizing the polyamic acid varnish is immersed in N-methyl-2-pyrrolidone at 80° C. for 5 minutes, and then filtered through a filter paper to measure the dissolution rate represented by the following formula, which is preferably 90% or more, more preferably 95% or more. Dissolution rate (%) = [1-[(weight of filter paper after filtration and drying)-(weight of filter paper before use)] / (weight of film before immersion)]×100

[0085] The solubility can be measured by the following procedure. First, the polyimide film obtained by imidizing the polyamic acid varnish is cut into a sample having a thickness of 20 μm and a size of 2.0 cm × 2.0 cm, and the weight of the sample (weight of the film before immersion) is measured in advance. The weight of the filter paper before use is also measured in advance. Next, the sample is added to N-methyl-2-pyrrolidone (NMP) to a concentration of 1% by mass to prepare a sample liquid, and the obtained sample liquid is left to stand in an oven heated to 80°C for 5 minutes. The sample liquid is then removed from the oven, filtered through filter paper, and dried under reduced pressure at 100°C. The weight of the filter paper after filtration and drying is then measured. The measured values ​​are applied to the above formula to calculate the dissolution rate. These operations are carried out twice, n=2, and the average value is taken as the dissolution rate (%).

[0086] The solubility of the polyimide film tends to be increased, for example, by increasing the content of the aliphatic monomer (A) or by using an aromatic tetracarboxylic dianhydride represented by formula (3-1) or an aromatic diamine represented by formula (4-1) as the aromatic monomer (B). In addition, the solubility of the resulting polyimide film tends to be increased by decreasing the diamine / acid dianhydride ratio.

[0087] 2. Manufacturing method of polyamic acid varnish The polyamic acid varnish can be obtained by subjecting the diamine and tetracarboxylic dianhydride to a polymerization reaction in a solvent containing the above-mentioned solvent having an amide skeleton or solvent having a sulfonyl skeleton.

[0088] The procedure of the polymerization reaction is not particularly limited. For example, first, a container equipped with a stirrer and a nitrogen inlet tube is prepared. The above-mentioned solvent is charged into the nitrogen-substituted container, and diamine is added so that the solid content concentration of polyamic acid is 5 to 30% by weight, and the temperature is adjusted to stir and dissolve. Tetracarboxylic dianhydride is added to this solution so that the molar ratio to the diamine is within the above-mentioned molar ratio (y / x), and the temperature is adjusted to stir for about 1 to 50 hours. After the polymerization reaction is completed, the solvent may be further added to dilute the mixture as necessary. Thereby, a varnish containing polyamic acid can be obtained.

[0089] The temperature during the polymerization reaction is not particularly limited as long as the polymerization reaction proceeds in the solvent containing the above-mentioned amide skeleton or sulfonyl skeleton. The temperature during the polymerization reaction can be, for example, higher than 70°C, for example, 80 to 90°C.

[0090] 3. Polyimide composition The polyimide composition according to the present embodiment is obtained by heating the polyamic acid varnish to form an imidized product, that is, the polyimide composition according to the present embodiment contains a polyimide which is a polycondensation product of the tetracarboxylic dianhydride and the diamine.

[0091] The temperature at which the polyamic acid is imidized may be, for example, 150 to 250°C. Therefore, if the temperature of the coating film is suddenly increased to 250°C or higher, the polyamic acid on the surface of the coating film is imidized before the solvent evaporates from the coating film. As a result, the solvent remaining in the coating film generates air bubbles or causes unevenness on the coating film surface. Therefore, in the temperature range of 50 to 250°C, it is preferable to gradually increase the temperature of the coating film. Specifically, the heating rate in the temperature range of 50 to 250°C is preferably 0.25 to 30°C / min, more preferably 1 to 20°C / min, and even more preferably 2 to 10°C / min.

[0092] The form of the polyimide composition is not particularly limited, and may be a varnish or a film. When the polyimide composition is a polyimide film, the polyimide film preferably satisfies the above-mentioned physical properties.

[0093] 4.Applications As described above, the polyimide composition contains a predetermined amount or more of the constitutional unit derived from the aliphatic diamine, and therefore has good lamination properties. Therefore, the polyimide composition can be used as an adhesive, a sealant, an insulating material, or a protective material in electronic circuit boards, semiconductor devices, surge components, etc.

[0094] For example, when the polyimide composition is used as an adhesive, it can be a laminate having a substrate and a resin layer containing the polyimide composition. The thickness of the resin layer is not particularly limited, but when it is used as a temporary fixing adhesive, it can be about 1 to 100 μm. The laminate can be produced, for example, by applying the polyamic acid varnish onto a substrate, heating it to imidize it, and then forming a resin layer containing the polyimide composition.

[0095] The material contained in the substrate may be silicon, ceramics, metal, or resin, depending on the application. Examples of metals include copper, aluminum, SUS, iron, magnesium, nickel, and alumina. Examples of ceramics include silicon carbide, gallium nitride, and gallium oxide. Examples of resins include urethane resin, epoxy resin, acrylic resin, polyimide, PET resin, polyamide, and polyamideimide. In particular, the substrate preferably contains at least one element selected from the group consisting of Si, Ga, Ge, As, and AI, more preferably a semiconductor substrate containing at least one element selected from the group consisting of Si, Ga, Ge, As, and AI, and particularly preferably a semiconductor substrate containing at least one element selected from the group consisting of silicon, silicon carbide, gallium nitride, gallium oxide, and sapphire.

[0096] Among these, the polyimide composition can be suitably used as a temporary fixing adhesive for semiconductor devices.

[0097] That is, in the manufacturing process of semiconductor devices, a back-grinding process is performed in which the back surface of the semiconductor wafer is ground to reduce the thickness of the semiconductor wafer. In the back-grinding process, the use of polyimide resin is being considered as a material for protecting the surface of the semiconductor wafer and for fixing a highly rigid support substrate (e.g., a glass substrate).

[0098] The polyimide resin used for such applications is required to be able to bond a semiconductor wafer and a supporting substrate to each other with good adhesion. As such a polyimide resin, the above-mentioned polyimide composition containing a predetermined amount or more of a constitutional unit derived from an aliphatic diamine can be suitably used.

[0099] 5. Manufacturing method of semiconductor devices 1A to 1F and 2A to 2C are schematic diagrams showing a method for manufacturing a semiconductor device according to one embodiment of the present invention.

[0100] The method for manufacturing a semiconductor device according to this embodiment includes the steps of 1) applying a polyamic acid varnish onto a substrate 10, heating it to imidize it, and forming a resin layer 20 (see FIGS. 1A and 1B), 2) bonding a support substrate 30 while heating the resin layer 20 (see FIG. 1C), and 3) grinding the surface of the bonded substrate 10 opposite to the resin layer 20 (see FIGS. 1D and 1E). Furthermore, this embodiment can also perform 4) processing the back surface of the ground substrate 10 (see FIG. 1F), 5) irradiating a laser beam to peel the support substrate 30 from the resin layer 20 (see FIGS. 2A and 2B), and 6) dissolving the remaining resin layer 20 in a solvent to remove it (see FIG. 2C).

[0101] Step 1) The polyamic acid varnish is applied onto the substrate 10, and then heated to imidize it, forming a resin layer 20 (see FIGS. 1A and 1B). The substrate 10 may be the above-mentioned base material, preferably a semiconductor substrate containing at least one selected from the group consisting of silicon, silicon carbide, gallium nitride, gallium oxide, and sapphire.

[0102] The method for applying the varnish is not particularly limited, and may be, for example, a spin coating method.

[0103] The applied varnish can be heated, for example, by an oven or a hot plate. The heating temperature may be any temperature that can imidize the polyamic acid and can remove the solvent until a self-supporting film is formed. In the case of imidization in one step, the temperature is raised from 20 to 50°C to a temperature range of 180 to 250°C, and the imidization can be performed by holding the reached temperature for a predetermined time. The specific reached temperature is preferably 180 to 250°C, more preferably 180 to 200°C. The rate of temperature rise is preferably 0.25 to 30°C / min, more preferably 1 to 20°C / min, and even more preferably 2 to 10°C / min. The holding time at the reached temperature is preferably 10 to 120 minutes, more preferably 20 to 60 minutes, and even more preferably 20 to 30 minutes.

[0104] When imidization is performed in two stages, the first stage is preferably at 50 to 150° C., and more preferably at 50 to 100° C. The second stage is preferably at 150 to 300° C., and more preferably at 150 to 250° C. The holding time in each stage is preferably 1 to 60 minutes, more preferably 2 to 15 minutes, and even more preferably 2 to 10 minutes. There are no particular limitations on the temperature change or time between each stage.

[0105] The thickness of the resin layer 20 is not particularly limited, but when used as a temporary fixing adhesive, for example, the thickness may be about 1 to 100 μm.

[0106] Step 2) Next, the resin layer 20 is heated to its melting temperature or higher, and a support substrate 30 is attached (see FIG. 1C).

[0107] The support substrate 30 may be any substrate having rigidity, such as a resin substrate, a ceramic substrate, or a glass substrate. From the viewpoint of performing LLO, the support substrate 30 is preferably a transparent support substrate such as a glass substrate. The thickness of the support substrate 30 is not particularly limited, but is preferably thicker than the thickness of the resin layer 20, and may be, for example, 50 to 1000 μm.

[0108] The heating temperature of the resin layer 20 may be equal to or higher than the melting temperature. The melting temperature means the melting temperature of the polyimide film obtained from the polyamic acid varnish. Specifically, the heating temperature during lamination may be equal to or higher than the melting temperature and equal to or lower than 350°C.

[0109] The method for heating the resin layer 20 is not particularly limited, and similarly to the above, it can be performed using an oven, a hot plate, etc. A predetermined pressure may be applied during lamination to perform thermocompression bonding.

[0110] Step 3) Next, the surface of the substrate 10 to which the support substrate 30 is attached, opposite to the resin layer 20, is ground (see FIGS. 1D and 1E), thereby thinning the substrate 10 to a predetermined thickness or less.

[0111] Other processes Furthermore, in this embodiment, the following steps are performed: 4) processing the ground back surface (see FIG. 1F); 5) irradiating laser light to peel the support substrate 30 from the resin layer 20 (see FIGS. 2A and 2B); and 6) dissolving the remaining resin layer 20 in a solvent to remove it (see FIG. 2C).

[0112] In the step 4) (back surface processing step), for example, ion implantation or annealing may be performed, followed by forming a collector layer to form a transistor 40 (insulated gate bipolar transistor, IGBT). Alternatively, a resist may be formed and patterned.

[0113] In step 5), laser light is applied to peel the support substrate 30 from the resin layer 20 (see FIGS. 2A and 2B).

[0114] The laser light may have a wavelength of 200 to 360 nm (preferably 355 nm). When the laser light is irradiated, the aromatic rings in the polyimide of the polyimide composition absorb the light, generating heat, which breaks the ether bonds and facilitates peeling.

[0115] In step 6), the remaining resin layer 20 is removed by contacting it with a solvent and dissolving it (see FIG. 2C).

[0116] The solvent used may be any solvent capable of dissolving the resin layer 20, and may be the same as the solvent used for the polyamic acid varnish. In this way, a substrate 10' having a processed rear surface can be obtained. EXAMPLES

[0117] The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to the description of the examples.

[0118] 1. Material Preparation 1-1. Aliphatic monomer (A) (Aliphatic diamine) Decanediamine: 1,10-diaminodecane Dioxadodecanediamine: 4,9-dioxane-1,12-dodecanediamine RT1000: Polyetheramine (HUNTSMAN, see formula below, Mw=1015) [ka]

[0119] 1-2. Aromatic Monomers (B) (Aromatic tetracarboxylic dianhydride) pBPADA: 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride)

[0120] (Aromatic diamine) p-BAPP: 2,2-bis(4-(4-aminophenoxy)phenyl)propane

[0121] 1-3.Solvent NMP: N-methyl-2-pyrrolidone GBL: gamma-butyrolactone KJCMPA-100: 3-Methoxy-N,N-dimethylpropanamide DMI: 1,3-Dimethyl-2-imidazolidinone DMSO: Dimethyl sulfoxide 1-Methylimidazole Ethyl acetoacetate Dimethyl malonate Methyl pyruvate

[0122] 2. Varnish Preparation and Evaluation [Examples 1 to 10, Comparative Examples 1 to 6] Tetracarboxylic dianhydride and diamine of the type and amount (mol %) shown in Table 1 were mixed in a solvent shown in the same table. The resulting mixture was stirred at 45 to 85°C for 5 hours or more in a flask into which dry nitrogen gas could be introduced, to obtain a polyamic acid varnish having a resin solid content of 20 to 30 mass %. The amount (molar ratio) of diamine and tetracarboxylic dianhydride charged was diamine / tetracarboxylic dianhydride = 0.93.

[0123] In addition, solid aliphatic diamine (decanediamine) has low solubility in a solvent at room temperature. Therefore, in Examples 3 to 10 and Comparative Examples 1 to 6 in which solid aliphatic diamine was used, the temperature was gradually increased from 45°C to 85°C to dissolve and melt the solid aliphatic diamine. After reaching 85°C and maintaining it for 30 minutes, the temperature was naturally decreased to 45°C to cause the reaction.

[0124] [evaluation] (1)E type viscosity The E-type viscosity of the resulting polyamic acid varnish was measured at 25° C. using an E-type viscometer.

[0125] (2) Intrinsic viscosity The intrinsic viscosity (η) of polyamic acid is the average value of three measurements taken at 25° C. using an Ubbelohde viscometer when a polyamic acid varnish is dissolved in N-methyl-2-pyrrolidone (NMP) to a concentration of 0.5 g / dL.

[0126] (3) Monomer solubility (when the monomer is solid) The solvent in Table 1 was placed in a vessel so that the solvent was 30% by mass relative to the total amount of monomers to be added. The acid dianhydride, aromatic diamine, and aliphatic diamine were then added in sequence, the temperature was raised, and the mixture was maintained at 75 to 85°C for a predetermined period of time or more while stirring. The solubility of the monomers was evaluated according to the following criteria. 〇: After heating at 75-85℃ for 30 minutes, the entire varnish becomes uniform and no undissolved residue can be visually confirmed. △: When heated at 75-85℃ for more than 30 minutes but less than 6 hours, the entire varnish becomes uniform and no undissolved residue can be visually confirmed. ×: Does not melt even when heated for more than 6 hours

[0127] (4) Solubility of salt (when monomer is liquid) When the monomers in Table 1 were reacted in a container in a solvent in the same table at the reaction temperature in the same table, the reaction product (salt) of the ring-opened product of the tetracarboxylic dianhydride and the diamine was visually observed to see if it precipitated, and was evaluated according to the following criteria. 〇: Aliphatic diamine (including compounds that are liquid at room temperature) is charged and no white precipitate is formed. △: The resulting white precipitate dissolves after reacting for a specified time at 45 to 85°C. ×: The white precipitate formed under the above conditions does not dissolve.

[0128] (5) Film formability The obtained polyamic acid varnish was applied onto a glass substrate using a bar coater, and then the temperature was raised from 50°C to 180-250°C at a rate of 5°C / min. After 30 minutes at the reached temperature, the temperature was lowered to room temperature, and it was evaluated whether the film formed. The film-forming properties were evaluated according to the following criteria. 〇: Forms a film △: A film was obtained under the above conditions, but the varnish turned white when applied. ×: Film not obtained under the above conditions

[0129] (6) Storage stability 1) The viscosity of the polyamic acid varnish immediately after preparation was measured as follows: 0.15 mL of polyamic acid varnish was placed in an E-type viscometer (Toki Sangyo Co., Ltd., VISCOMETER TV-25), preheated at 25°C for 120 seconds, and then measured 240 seconds after the end of preheating at a rotation speed where the torque was 0-80% at 25°C using a cone rotor (3° x R9.7). 2) Next, a predetermined amount of the prepared polyamic acid varnish was taken, sealed in a 10 mL vial, and stored at room temperature (25°C) for a certain period of time. The E-type viscosity of the polyamic acid varnish taken out of the vial was then measured in the same manner as above. 3) Next, the viscosity before and after storage was applied to the following formula to calculate the rate of change. Change rate (%) = ((viscosity after storage - viscosity before storage) / viscosity before storage) x 100 The storage stability was evaluated according to the following criteria. ○: Change rate is ±10% or less △: Change rate is more than ±10% and 20% or less ×: Change rate exceeds ±20% The same evaluation was also performed when the storage temperatures were refrigerated (3 to 8°C) and frozen (-19 to -14°C).

[0130] The evaluation results of Examples 1 to 10 and Comparative Examples 1 to 6 are shown in Table 1.

[0131] [Table 1]

[0132] As shown in Table 1, the polyamic acid varnish of Comparative Example 1 had poor solubility of the monomer and salt, and was found to hardly react at all.

[0133] In contrast, the polyamic acid varnishes of Examples 1 to 10 have good monomer solubility and salt solubility, which indicates that the reaction has occurred, and also have excellent film-forming properties, which indicates that polyamic acids having a good degree of polymerization can be obtained.

[0134] From these findings, it can be seen that by using a solvent having an amide skeleton other than NMP or a solvent having a sulfoxide skeleton as an alternative solvent to NMP, a varnish containing a polyamic acid with a predetermined degree of polymerization can be obtained even if it contains a large amount of aliphatic diamine.

[0135] In particular, when a solvent having a sulfoxide skeleton is used as the solvent, the storage stability is somewhat poor, but it is clear that the decrease in storage stability can be suppressed by blending with DMI.

[0136] 3. Evaluation of various physical properties and melt lamination properties The following physical properties (glass transition temperature, melting temperature, complex viscosity) were measured for the varnish of Example 5 in Table 1. In addition, the melt lamination property of the resulting polyimide film was evaluated by the following method.

[0137] (1) Glass transition temperature The varnish was applied onto a glass plate, and the temperature was raised from 50°C to the heating temperature at a rate of 5°C / min in the atmosphere, and the heating temperature was maintained for 30 minutes to form a polyimide film. The heating temperature of the polyamic acid varnish 7 was 180°C.

[0138] Next, the obtained polyimide film was cut into a size of 5 mm in width and 22 mm in length, and the glass transition temperature (Tg) of the obtained sample was measured using a TMA-50 manufactured by Shimadzu Corporation. Specifically, the temperature was raised from less than 50°C to 180 to 250°C at a heating rate of 5°C / min in an air atmosphere, and the measurement was performed in a tensile mode (100 mN). The Tg was calculated by extrapolating the curves before and after the inflection point due to the glass transition in the obtained curve.

[0139] (2) Melting temperature, complex viscosity The polyimide film formed in (1) above was cut into a number of pieces each having a diameter of 15 to 25 mm, and these were stacked to prepare samples having a thickness of 0.5 to 2 mm.

[0140] The above sample was set in a TA Instruments ARES-G2 rheometer, heated to a predetermined temperature at a frequency of 1 Hz and a heating rate of 3°C / min, and the melt viscoelasticity was measured. In the temperature range above the glass transition temperature in the obtained measurement results, the point at which the storage modulus and the loss modulus are equal (the temperature at which tan δ=1) is the melting point, and the temperature at which the melting point is reached was taken as the melting temperature. In addition, the complex viscosity at the melting temperature (melting point) obtained at the same time under the same conditions was also determined.

[0141] The results of these measurements are shown in Table 2. [Table 2]

[0142] (3) Melt bonding ability For the varnish of Example 5 in Table 1, the varnish was dropped onto a silicon wafer with a diameter of 300 mm and applied by spin coating. This was placed on a hot plate and heated at 80°C for 5 to 10 minutes, and then further heated at 200 to 250°C for 5 to 10 minutes. Then, a glass substrate with a diameter of 300 mm was pressed against the wafer at a pressure of 20 to 30 kN at 220 to 280°C for 5 minutes to bond the wafer.

[0143] When the glass substrates were bonded together, the presence or absence of air bubbles was visually observed, and no air bubbles were found within the range that could be visually confirmed. This confirmed that good bonding properties could be obtained even when using an alternative solvent to NMP. [Industrial Applicability]

[0144] According to the present invention, it is possible to provide a varnish containing a polyamic acid containing a predetermined amount or more of an aliphatic diamine, which is prepared using an alternative solvent to NMP. [Explanation of symbols]

[0145] 10 Substrate 10' Backside processed board 20 Resin layer 30 Support substrate 40 Transistor

Claims

1. A polyamic acid varnish comprising a polyamic acid and a solvent, The polyamic acid is a polyaddition product of a tetracarboxylic dianhydride and a diamine, The diamine comprises an aliphatic diamine (Aa) having an amino group bonded to an aliphatic group; the content of the aliphatic diamine (Aa) is 5.0 mol % or more based on the total amount of the monomer composed of the tetracarboxylic dianhydride and the diamine, The solvent includes a solvent having an amide skeleton (excluding N-methyl-2-pyrrolidone) or a solvent having a sulfoxide skeleton. Polyamic acid varnish.

2. The solvent includes a solvent having an amide skeleton. The polyamic acid varnish according to claim 1 .

3. The solvent having an amide skeleton has a cyclic structure. The polyamic acid varnish according to claim 2 .

4. The solvent having an amide skeleton includes 1,3-dimethyl-2-imidazolidinone. The polyamic acid varnish according to claim 1 .

5. the total content of the solvent having an amide skeleton and the solvent having a sulfoxide skeleton is 60 mass% or more based on the total amount of the solvents; The polyamic acid varnish according to claim 1 .

6. The aliphatic diamine (Aa) contains at least one of an aliphatic diamine represented by formula (1) and an aliphatic diamine represented by formula (2), The polyamic acid varnish according to claim 1 . 【Chemistry 1】 (In formula (1), R １ is an aliphatic chain having a main chain composed of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is 21 to 500. 【Chemistry 2】 (In formula (2), R ２ is an aliphatic chain having a main chain composed of one or more atoms of C, N, and O, and the total number of atoms constituting the main chain is 5 to 20.

7. The monomer contains at least one of an aromatic tetracarboxylic dianhydride represented by formula (3) and an aromatic diamine represented by formula (4), The polyamic acid varnish according to claim 1 . 【Chemistry 3】 【Chemistry 4】 (R in formula (3) ２ and R in formula (4) ３ are divalent groups each having a main chain composed of one or more atoms of C, N, or O, and the total number of atoms constituting the main chain is 2 to 100.

8. The aromatic tetracarboxylic dianhydride represented by the formula (3) includes an aromatic tetracarboxylic dianhydride represented by the formula (3-1), The aromatic diamine represented by the formula (4) includes an aromatic diamine represented by the formula (4-1): The polyamic acid varnish according to claim 7. 【Chemistry 5】 (In formula (3-1), Y is an oxygen atom, a methylene group, or -CR ａ R ｂ (R ａ and R ｂ represents a divalent group selected from the group consisting of substituted or unsubstituted alkyl groups each having 1 to 3 carbon atoms, m represents an integer of 0 or 1; R ５ and R ６ represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms, e and f each represent an integer of 0 to 3. 【Chemistry 6】 (In formula (4-1), Z is an oxygen atom, a methylene group, or -CR ｃ R ｄ (R ｃ and R ｄ represents a divalent group selected from the group consisting of substituted or unsubstituted alkyl groups each having 1 to 3 carbon atoms, n represents an integer of 0 or 1; R ７ and R ８ represents a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms, g and h each represent an integer of 0 to 3.

9. the total content of the aromatic tetracarboxylic dianhydride represented by the formula (3-1) and the aromatic diamine represented by the formula (4-1) is 60 to 90 mol % based on the total amount of the monomers; The polyamic acid varnish according to claim 8.

10. A step of applying the polyamic acid varnish according to claim 1 onto a substrate and then imidizing the varnish to form a resin layer; a step of heating the resin layer to a melting temperature or higher and bonding a support substrate; Including, A method for manufacturing a semiconductor device.

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