JP5699607B2 - Polyimide precursor solution for ultra-thin device manufacturing - Google Patents

Description

  The present invention is an ultrathin device substrate as a display device such as a liquid crystal display substrate, an organic EL display substrate, an electronic paper substrate, etc., in various ultrathin devices excellent in low thermal expansion, high heat resistance, and toughness, and a thin film solar cell The present invention relates to a polyimide precursor solution (resin composition) that is used for an ultrathin device substrate as a photoelectric conversion device, and more particularly to a polyimide precursor solution (resin composition) that is useful as a substrate for a flat panel display. Moreover, this invention relates to the ultra-thin device obtained by the manufacturing method of the ultra-thin device using the said polyimide precursor solution (resin composition), and the said manufacturing method.

  Currently, glass substrates are used for various displays, but the glass substrates have a problem that the strength decreases when the weight and thickness are reduced. Therefore, as a substitute for the glass substrate, it is required to adopt a plastic substrate that can be thinned because it is lightweight and easy to mold. If a plastic substrate having higher toughness than a glass substrate can be adopted, it is expected to realize a flat panel display that can be bent and rolled. Furthermore, if a film substrate can be used, it is expected that a highly productive production process will be established by a roll-to-roll process.

However, especially in the display device field, the existing production line is built on the premise of using a single-wafer glass substrate, etc., so the production infrastructure has been fundamentally changed to introduce the roll-to-roll process. There is a need to. This requires enormous economic resources and peripheral technology development, and it is impractical to quickly introduce a roll-to-roll process.
On the other hand, in the process of forming a display device, particularly a TFT array, processing that requires precise alignment over a large area is required by a photolithographic method, a printing method, or the like. Many film substrates have a lower modulus of elasticity, a larger coefficient of linear expansion, and irreversible dimensional changes due to heating, humidification, etc. There are many. In particular, when processing a display device with a large area, the positional deviation in the peripheral portion becomes significant, and thus the size of the device that can be processed may be limited.

In order to solve these problems, a method of temporarily fixing a film substrate to a hard substrate with an adhesive or the like has been devised. By fixing the film to the hard substrate, the display device can be processed using the existing hard substrate processing infrastructure. In addition, since the dimensional accuracy is almost controlled by the hard substrate, high alignment accuracy can be expected even in processing of a large area. However, especially when handling materials that require high temperatures for thin film formation, such as inorganic semiconductors, more specifically amorphous silicon, microcrystalline silicon, and compound semiconductors, the heat resistance of the film material as well as the adhesive used for temporary fixing. The heat resistance of the agent becomes a problem. Even when a highly heat-resistant polyimide film is used as the film base material, if the substrate is exposed to high temperatures in a vacuum thin film process, many adhesives have a significant decrease in adhesive strength at high temperatures, and the substrate is still being processed. Gas generation is caused by peeling from the substrate and thermal deterioration of the pressure-sensitive adhesive itself, which significantly impedes the process and makes it difficult to form a target semiconductor thin film.
To solve this problem, for example, a film precursor is applied on a hard carrier substrate, as exemplified in Patent Document 1 and Patent Document 2, and the film is formed on the hard carrier substrate. A display manufacturing method has been proposed in which a display device is formed thereon and finally the display device is peeled off from the hard carrier substrate together with the film. According to this method, it is an advantage that a thin and lightweight substrate can be formed rather than using an independent film-like substrate in advance. In addition, since materials with low heat resistance such as pressure-sensitive adhesives do not intervene, it is said that by using heat-resistant materials such as parylene and polyimide as film materials, it is possible to form even thin film devices that require high film forming temperatures. . However, when such a method is used, a generally obtained film is a brittle film having inferior strength and breaking elongation compared to a film made of the same material produced by a film making machine having a dedicated stretching process. In many cases. In addition, the adhesiveness between the hard carrier substrate and the film cannot be controlled. As a result, the film is broken when the film is peeled off from the hard carrier substrate, or the device on the film is broken because the film is stretched by the peeling force. It is difficult to avoid troubles.

  Recently, it has become possible to produce a thin glass plate having a thickness of less than 50 μm. Even glass can be bent flexibly when this thickness is reached. However, brittleness and fragility, which are essential problems of glass, have not been solved. In particular, it is very dangerous if finely broken glass pieces scatter when broken. In a display device using a glass plate, sticking a polymer film as a standard method has been established to reinforce and prevent scattering of broken pieces when broken. However, it is general that these scattering prevention films are attached to glass after the device is completed. This is because many polymer films are vulnerable to the high temperatures required for manufacturing semiconductor devices and exposure to acids, alkalis, organic solvents, and the like. Therefore, in an ultra-thin device using a glass plate as a substrate, it is necessary to handle without a protective film, an anti-scattering film, etc. during the manufacturing process, and therefore, for cracking or chipping of the substrate during the process, Decreasing product yield is a major issue.

Special table 2007-512568 gazette JP 2010-202729 A

  The present invention is an ultrathin device that is a liquid crystal display, an organic EL display, an electronic paper display device, or a solar cell light-receiving device. A thin film is formed, and a circuit or display layer can be formed on the resin thin film, and it becomes a polyimide film having excellent heat resistance and a low coefficient of thermal expansion. A liquid polyimide precursor solution for forming an ultrathin device substrate (resin composition) that does not cause warping of the substrate layer, does not cause defects such as circuit peeling, and can be peeled off from the carrier substrate without causing defects. Product), an ultrathin device using the same, and a manufacturing method thereof.

In producing ultra-thin devices, the present inventors have found that a specific polyamic acid solution obtained by a reaction between an aromatic tetracarboxylic acid and an aromatic diamine having a benzoxazole structure (skeleton) is an inorganic carrier substrate. Applying, drying and imidizing to form a coating film, having sufficient adhesive force to form a device on the coating film, and destroying the device when peeled off from the carrier substrate after forming the device It was found that the film can be peeled without any further, shows a linear expansion coefficient of -5 pm / K to 8 ppm / K when measured in two orthogonal directions, and gives a polyimide film that can be handled as an ultra-thin device. The present invention has been reached.
That is, the present invention has the following configuration.
1. Applying and drying a polyimide precursor solution onto an inorganic substrate selected from glass, ceramic, etc.-Heat-treating to obtain a laminate composed of an inorganic substrate / polyimide film, and a thin film on the polyimide film surface or the inorganic substrate surface of the laminate In the polyimide precursor solution used in the manufacturing process of ultra-thin devices obtained by forming devices, the polyimide precursor solution consists of a solvent, an aromatic tetracarboxylic anhydride, a dicarboxylic anhydride, and a benzazole skeleton. A polyamic acid solution mainly composed of a polyamide obtained from diamines having carboxylic acids, and having a mole number An of the carboxylic anhydride groups possessed by the aromatic tetracarboxylic anhydrides and a carboxylic acid possessed by the dicarboxylic anhydrides. The number of moles Bn of acid anhydride groups and the number of moles Cn of amino groups possessed by diamines are as follows: 1) The polyimide precursor solution characterized by satisfy | filling Formula and (2) Formula simultaneously.
0.90 ≦ Cn / (An + Bn) <1.0 (1)
0 ≦ Bn / An ≦ 0.05 (2)
2. 1. The linear expansion coefficient of the polyimide film is −5 ppm / ° C. to +8 ppm / ° C. Polyimide precursor solution for manufacturing ultrathin devices.
3. 1. The peeling force of the polyimide film from the inorganic substrate is 1.6 N / cm to 20 N / cm. Or 2. Polyimide precursor solution for manufacturing ultrathin devices.
In the present application, tetracarboxylic dianhydride is counted as two carboxylic anhydride groups per molecule, and dicarboxylic anhydrides are counted as one carboxylic anhydride group.

  Excellent durability even in high temperature environments, durability even when exposed to high temperatures during circuit formation, and little expansion and contraction, so stress is not applied to electrical circuits and semiconductor elements. Since there is little difference in the coefficient of linear expansion, it is possible to produce stable electric wiring and electric elements because warpage hardly occurs even when a circuit is formed at a high temperature on a laminate with an inorganic substrate. Compared to inorganic layers, it is easy to create a flat surface with a small surface roughness, so it is very useful for creating electronic devices that are easy to create fine wiring, have insulation, flexibility, and heat resistance. Moreover, it is a useful polyimide precursor solution for manufacturing an ultra-thin device that also has appropriate adhesiveness.

  The polyimide precursor solution for manufacturing an ultrathin device of the present invention is a polyimide film (layer) formed thereafter is a self-supporting polyimide film, and is obtained by reaction of aromatic tetracarboxylic acids and aromatic diamines. The polyimide film has a linear expansion coefficient (both in the film length direction and width direction) of −5 ppm / ° C. to +8 ppm / ° C., and the polyimide film peeling force from the inorganic substrate (hereinafter referred to as 90) Degree peel strength) is 1.6 N / cm to 20 N / cm, preferably 2.5 to 14 N / cm, more preferably 3.5 to 11 N / cm, and still more preferably 4.2 to 8.N. It is 9 N · cm, does not peel off at the time of device molding, and can be used as a reinforcing coating after device completion. Aromatic tetracarboxylic acids (anhydrides, acids And a polyamic acid solution obtained by reacting an aromatic diamine (collectively referred to as an amine and an amide-bonded derivative, hereinafter the same) and an aromatic diamine (hereinafter referred to as a class). A polyimide obtained by a method of forming a film (film) by rolling, drying, and heat treatment (imidization) is preferable, and a precursor solution (polyamic acid solution) of these polyimides.

In the polyimide precursor solution for manufacturing an ultrathin device of the present invention, the mole number An of the carboxylic anhydride group possessed by the aromatic tetracarboxylic anhydride and the mole of the carboxylic anhydride group possessed by the dicarboxylic anhydride. It is essential that the number Bn and the number of moles Cn of the amino group of the diamine satisfy the relations (1) and (2) at the same time.
0.90 ≦ Cn / (An + Bn) <1.0 (1)
0 ≦ Bn / An ≦ 0.05 (2)
Cn / (An + Bn) in the present application is 0.95 ≦ Cn / (An + Bn) <1.0 (1 ′)
Is preferred,
0.97 ≦ Cn / (An + Bn) <1.0 (1 ″)
Is still preferred,
0.98 ≦ Cn / (An + Bn) <1.0 (1 ''')
Is more preferred,
0.98 ≦ Cn / (An + Bn) <0.999 (1 '''')
Is still more preferred.
Bn / An in this application is
0 ≦ Bn / An ≦ 0.08 (2 ')
Is preferable 0 <Bn / An ≦ 0.08 (2 '')
Is still preferably 0 <Bn / An ≦ 0.03 (2 ''')
Is more preferable 0.001 <Bn / An ≦ 0.02 (2 '''')
Is even more preferred.
When deviating from this range, there are many cases where the tensile breaking strength and tensile breaking elongation of the formed polyimide film cannot be sufficient, and the peeling force of the polyimide film from the inorganic substrate is 1.6 N. When the linear expansion coefficient of the film (polyimide film) (both in the film length direction and the width direction) deviates from the range of -5 ppm / ° C. to +8 ppm / ° C. Therefore, it does not become a useful polyimide precursor solution for manufacturing an ultrathin device.
Examples of the solvent used in these solutions include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide and the like.

  The molecular structure of aromatic diamines having a benzoxazole structure used in the present invention is not particularly limited, and specific examples include the following.

  Among these, from the viewpoint of easy synthesis, each isomer of amino (aminophenyl) benzoxazole is preferable, and 5-amino-2- (p-aminophenyl) benzoxazole is more preferable. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.

  In the present invention, one or two or more diamines exemplified below may be used in combination as long as they are 30 mol% or less of the total diamine. Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diamino Diphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodi Phenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4, 4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4 '-Diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) ) Phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) Phenyl] propane, 1,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4 -Aminophenoxy) phenyl] propane, 1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [ 4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-Aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3- Tilphenyl] propane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4- Aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,4- Bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfone Hydroxide, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [ 4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 4, 4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane 3,4′-diaminodiphenyl sulfide, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3- Hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) Phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3-amino Phenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethyl) Benzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4 (4-Aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α -Dimethylbenzyl] benzene, 3,3'-diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino- 4,5′-diphenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone, 4,4′-diamino-5-phenoxybenzophenone, 3,4′-diamino-4-phenoxybenzophenone, 3,4′- Diamino-5'-phenoxybenzophenone, 3,3'-diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5 '-Dibiphenoxybenzophenone, 3,3'-diamino-4-biphenoxybenzophenone, 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'- Diamino-5′-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benze 1,4-bis (3-amino-4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) Benzene, 1,3-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5- Biphenoxybenzoyl) benzene, 1,4-bis (4-amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzonitrile, 1 , 3- (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane and part or all of the hydrogen atoms on the aromatic ring of the aromatic diamine Or a halogenated alkyl group having 1 to 3 carbon atoms, in which part or all of the hydrogen atoms of the rogen atom, alkyl group having 1 to 3 carbon atoms or alkoxyl group, cyano group, or alkyl group or alkoxyl group are substituted with a halogen atom, or And aromatic diamines substituted with alkoxyl groups.

<Aromatic tetracarboxylic acid anhydrides>
Specific examples of the aromatic tetracarboxylic acid anhydrides used in the present invention include the following.

  These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when the polyamic acid is obtained by reacting (polymerizing) the aromatic tetracarboxylic acid and the aromatic diamine is not particularly limited as long as it dissolves both the raw material monomer and the produced polyamic acid. Is preferably a polar organic solvent, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, Examples include hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, and halogenated phenols. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the weight of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by weight, The amount is preferably 10 to 30% by weight.

  Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for minutes to 30 hours. The temperature may be raised or lowered, for example, by dividing the polymerization reaction if necessary. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The weight of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by weight, more preferably 10 to 30% by weight, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). In order to obtain the polyimide layer, it is preferably 10 to 2000 Pa · s, more preferably 100 to 1000 Pa · s.

Vacuum defoaming during the polymerization reaction is effective for producing a good quality polyamic acid solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. As the terminal blocking agent, a monoamine compound or a dicarboxylic acid anhydride can be used, and a dicarboxylic acid anhydride is preferable. Examples of dicarboxylic acid anhydrides used in the present invention include acid anhydrides such as oxalic acid, malonic acid, maleic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and phthalic acid. An acid anhydride having a double bond such as maleic acid is preferable. Furthermore, it is also possible to use an acetylene-based compound having a dicarboxylic acid or monoamine form and having a terminal end function of polyimide. For example, 4-ethynyl phthalic anhydride and 4-phenylethynyl phthalic anhydride are mentioned. Among the terminal terminators, dicarboxylic acid anhydrides can be used within the specified range as counted in the acid anhydride group of the present invention.
In order to form a polyimide film from the polyamic acid solution obtained by the polymerization reaction, there is a method in which the polyamic acid solution is applied on an inorganic substrate, dried, and subjected to a heat treatment at a high temperature to cause an imidization reaction. The application of the polyamic acid solution to the inorganic substrate includes casting from a die with a slit, extrusion by an extruder, slit coating, screen printing, reverse coating, etc., but is not limited thereto, and conventionally known solution coating means are used. It can be used as appropriate.

In the polyimide precursor solution in the present invention, it is also possible to add and contain particles in the solution to give fine irregularities on the surface of the film (film) to improve the adhesiveness of the layer (film). As particles, inorganic or organic fine particles having an average particle diameter of about 0.03 μm to 0.8 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, pyrophosphoric acid. Fine particles such as calcium, magnesium oxide, calcium oxide, and clay minerals are listed.
These fine particles are preferably contained in the range of 0.20 to 2.0 mass% with respect to the polyimide. When the content of the fine particles is less than 0.20% by mass, there is not so much improvement in adhesion, which is not preferable. On the other hand, if it exceeds 2.0% by mass, the surface unevenness becomes too large, and even if the adhesiveness is improved, problems such as a decrease in smoothness remain, which is not preferable.
When the wiring width of the electric circuit becomes finer, it is desirable that the particle diameter of the particles is sufficiently smaller than the wiring width. For this reason, what does not contain particles having a major axis of 20 nm or more in the portion of the polyimide layer thickness direction at least 3 μm on the side where the electric circuit is formed is also desired. As a result, the polymer layer on the side in contact with the electric circuit layer becomes smooth, and the probability of contact with the smooth electric circuit layer at the atomic level increases, making it suitable for bonding. Preferably, the polymer layer on the side in contact with the electric circuit layer does not contain particles having a major axis of 20 nm or more in a portion of 5 μm or more.

The inorganic substrate in the present invention means a plate made of a hard and brittle material such as glass and ceramics.
The glass layer as the inorganic substrate in the laminate used in the present invention is quartz glass, high silicate glass (96% silica), soda lime glass, lead glass, aluminoborosilicate glass, borosilicate glass (Pyrex (registered trademark)) )), Borosilicate glass (no alkali), borosilicate glass (microsheet), aluminosilicate glass. Among them, those having a linear expansion coefficient of 5 ppm / ° C. or less are desirable, and liquid crystal glass Corning 1753, Eagle XG, Nippon Electric Glass OA-10G, Asahi Glass AN100, and the like are desirable.

, AL ₂ O ₃ is a ceramic layer in the laminate of the present invention _{Mullite, AlN, SiC, Si 3} N 4, crystallized glass, Cordierite, Spodumene, Pb-BSG + CaZrO3 + Al2O3, Crystallized glass + Al2O3, Crystallized Ca-BSG, BSG + Quartz, BSG + Quartz, BSG + Al2O3, Pb-BSG + Al2O3, Glass-ceramic, Zero-durer base ceramics, TiO2, Strontium titanate, Calcium titanate, Magnesium titanate. Capacitor materials such as alumina, MgO, steatite, BaTi4O9, BaTi03, BaTi03 + CaZrO3, BaSrCaZrTio3, Ba (TiZr) O3, PMN-PT PFN-PFW, PbNb2O6, Pb0.5Be0.5Nb2O6, PbTiO3, BaTiO3, PZT. This includes piezoelectric materials such as 95PT-0.5BT, 0.873PZT-0.97PT-0.3BT, PLZT.

  The inorganic substrate in the present invention can further include a silicon wafer, a SiC wafer, a diamond wafer, a GaAs wafer, and the like.

In the laminated body composed of the inorganic substrate and the polyimide film in the present invention, the polyimide film (layer) has a sufficient insulating property and takes longer to dry if it is thicker than maintaining electrical characteristics and other characteristics. Is difficult, and costs and time are required to form the film. Therefore, the realization range is 0.5 μm to 50 μm, and more preferably 1 μm to 25 μm. In the present application, a device in which a device described later is formed on a thin film in the thickness range is referred to as an ultrathin device.
The thickness of the inorganic substrate in the laminate used in the present invention is in the range of 1 to 1200 μm, preferably in the range of 2 to 450 μm, more preferably in the range of 2.8 to 160 μm, still more preferably. It is in the range of 3.6 μm to 70 μm, more preferably 4.8 to 27 μm.

  With the linear expansion coefficient in this invention, the average value measured between 30 to 400 degreeC is computed as CTE. Metals and ceramics often do not change within this temperature range, but polyimide layers may change CTE within this temperature range, but the lower limit of measurement can be replaced with 0 ° C, 30 ° C, or 50 ° C. It is possible to replace the upper limit of measurement with 200 ° C, 300 ° C, and 450 ° C.

  The linear expansion coefficient of the inorganic substrate (layer) as the inorganic substrate in the laminate used in the present invention is −5 ppm / ° C. to +8 ppm / ° C., more preferably +2 ppm / ° C. to +7 ppm / ° C. This is derived from the fact that glass and silicon wafers frequently used as 1.2 to 1.2 ppm / ° C. to 3.5 ppm / ° C. If it is larger than this, a stress may be partially applied at the time of thermal history or circuit formation, and warpage and peeling of the polyimide layer are likely to occur.

  The 90-degree peel strength in the present invention is preferably 1.6 N / cm to 20 N / cm, more preferably 2.5 to 9.5 N / cm, and still more preferably 3.8 to 7.2 N / cm. If it is less than 1.6 N / cm, it is difficult to use it as a practical device, and if it exceeds 20 N / cm, troubles often occur when the polyimide film is peeled off from the inorganic substrate.

The ultrathin device in the present invention is a substrate in which an electronic circuit or MEMS element composed of an active device, a passive device, a sensing device, a light emitting device, a light receiving device, a fine mechanism component, etc. is formed on a base material made of a polymer film. Say.
These ultra-thin devices are often provided with metal wiring for connecting elements. Here, the metal is mainly composed of copper, Al, Ni, Au, Ag, Cr, Mo, Ti, W, or the like. This refers to metal wiring. Desirably, the thing which contains NiCr alloy and Ti alloy as a barrier layer between a copper wiring and a polyimide film is mentioned.
A semiconductor element can be illustrated as an active element in this invention. The semiconductor element in the present invention includes a power semiconductor element, a thin film transistor, a sensor, a solar cell or a logic circuit, a MEMS element, a light emitting element, a light receiving element, an actuator element, and a device to which a commercially available semiconductor element chip is attached. .
The power semiconductor element in the present invention is a semiconductor optimized for power conversion and control, and has a higher breakdown voltage, higher current, higher speed and higher frequency than a normal semiconductor element. Includes rectifier diodes, power transistors, power MOSFETs, insulated gate bipolar transistors (IGBT), thyristors, gate turn-off thyristors (GTO), and triacs.
The thin film transistor in the present invention refers to a semiconductor layer in which a transistor and an insulating film, an electrode, a protective insulating film, and the like constituting an element are formed by depositing a thin film. It is usually distinguished from silicon wafers that use silicon as the semiconductor layer. Usually, a thin film is produced by a technique using a vacuum, such as PVD (physical vapor deposition) such as vacuum vapor deposition, or CVD (chemical vapor deposition) such as plasma CVD. For this reason, what is not a single crystal like a silicon wafer is included. Even if Si is used, microcrystalline silicon TFT, high-temperature polysilicon TFT, low-temperature polysilicon TFT, oxide semiconductor TFT, organic semiconductor TFT, and the like are included.
The sensor in the present invention is a strain gauge, a load cell, a semiconductor pressure sensor, an optical sensor, a photoelectric element, a photodiode, a magnetic sensor, a contact temperature sensor, a thermistor temperature sensor, a resistance temperature sensor temperature sensor, a thermocouple Temperature sensor, non-contact temperature sensor, radiation thermometer, microphone, ion concentration sensor, gas concentration sensor, displacement sensor, potentiometer, differential transformer displacement sensor, rotation angle sensor, linear encoder, tachometer, rotary encoder, optical position sensor (PSD), ultrasonic distance meter, capacitance displacement meter, laser Doppler vibration velocity meter, laser Doppler velocimeter, gyro sensor, acceleration sensor, earthquake sensor, one-dimensional image, linear image sensor, two-dimensional image, CCD image sensor , CMOS image sensor, liquid, leak sensor (leak sensor), liquid sensor (level sensor), hardness sensor, electric field sensor, current sensor, voltage sensor, power sensor, infrared sensor, radiation sensor, humidity sensor, odor sensor, Flow sensors, tilt sensors, vibration sensors, time sensors, composite sensors that combine these sensors, sensors that output other physical quantities or sensitivity values based on some calculation formula from the values detected by these sensors, etc. Included MEMS in the present invention refers to an object created using MEMS technology, an inkjet printer head, a probe for a scanning probe microscope, a contactor for an LSI prober, an optical spatial modulator for maskless exposure, an optical integrated device , Infrared sensor, flow sensor, Degree sensor, MEMS gyro sensors, RF MEMS switches, and body-external pressure sensor includes a grating light valve, a video projector that uses a digital micromirror device, and the like.
The solar cell in the present invention is formed by forming a laminate including a photoelectric conversion layer made of a semiconductor on the polyimide layer of the laminate described above.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in the following examples is as follows.

1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube. (When the solvent used for preparing the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved using N, N-dimethylacetamide and measured.)
2. Thickness of polyimide layer, etc. Measured using a micrometer (Finereuf, Millitron 1245D).
3. The tensile elastic modulus, tensile breaking strength, and tensile breaking elongation of the polyimide layer were applied to a polyamide precursor solution (varnish) on an 8-inch silicon wafer. The coating was adjusted with a spin coater so that the film thickness after firing was 20 μm. After drying at 100 ° C. for 10 minutes, it was placed in a muffle furnace in which N 2 was flowing, and 3 ° C./min. The temperature was raised from room temperature to 350 ° C. at 350 ° C., and the varnish was calcined at 350 ° C. for 1 hour. What peeled off the polyimide membrane | film | coat (film) after this was measured as a test piece what was cut out to the strip shape of 100 mm x 10 mm. Using a tensile tester (manufactured by Shimadzu Corporation, Autograph (R) model name AG-5000A), the tensile modulus, tensile breaking strength, and tensile breaking elongation were measured under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm. did.
4. 90 degree peeling strength According to JIS C6471 90 degree peeling method, the peeling strength of the sample was calculated | required by performing a 90 degree peeling test on the following conditions. In the sample for measuring peel strength, the polyimide film is applied to the inorganic layer before patterning. Measured with the one attached in the same manner as above. The average value of N = 5 measurements was taken as the measurement value.
Device name: Autograph AG-IS, manufactured by Shimadzu Corporation
Measurement temperature: room temperature Peeling speed: 50 mm / min.
Atmosphere: Air Measurement sample width: 1cm

5. Linear expansion coefficient (CTE)
3. above. The polyimide layer to be measured was measured in the same manner as described above, and the stretch rate was measured under the following conditions in two directions orthogonal to each other, and 30 ° C. to 45 ° C., 45 ° C. to 60 ° C. The stretch rate / temperature was measured, this measurement was performed up to 400 ° C., and the average value of all measured values was calculated as CTE. The sample is the above-mentioned 3. Samples for measuring the tensile modulus, tensile breaking strength and tensile breaking elongation of the polyimide film were used.
Device name: TMA4000S manufactured by MAC Science
Sample length; 20mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere; Argon load; 35 g / mm ²
Measurement of 6.5% weight loss temperature The polyimide film was peeled off from the glass / polyimide laminate, and the polyimide film was used as a sample to measure the 5% weight loss temperature. The measurement was performed using a TGA apparatus manufactured by Shimadzu Corporation, and the temperature was increased from room temperature to 150 ° C. at a heating rate of 10 ° C./min under an argon atmosphere, and the adsorbed water was sufficiently volatilized by holding at 150 ° C. for 30 minutes. Thereafter, the temperature was raised to 700 ° C. at a temperature rising rate of 10 ° C./min, and the obtained weight loss curve was read at a temperature 5% lower than the weight at the time of holding at 150 ° C. for 30 minutes.
7). Evaluation method of heat resistance, alkali resistance, acid resistance, solvent resistance Put the glass / polyimide laminate in a dry oven maintained at 400 ° C for 60 minutes, take it out and cool it to room temperature, whether film peeling or blistering occurs Appearance observation such as presence / absence was conducted to evaluate heat resistance.
Each sample was immersed in a 5% sodium hydroxide solution, 10% sulfuric acid, and toluene for 24 hours at room temperature, and then the appearance was observed to evaluate the alkali resistance, acid resistance, and solvent resistance, respectively.
8). Ra value measurement Surface morphology (roughness) was measured by using a scanning probe microscope with a surface physical property evaluation function (SP300 / SPI3800N manufactured by SII Nanotechnology Inc.). The measurement was performed in the DFM mode, and DF3 or DF20 manufactured by SII Nano Technology Co., Ltd. was used as the cantilever. The scanner used was FS-20A, the scanning range was 2 μm square, and the measurement resolution was 512 × 512 pixels. For the measurement image, the secondary inclination correction was performed, and then the Ra value was calculated using software attached to the apparatus.

<< Production Example 1 >>
After the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 5-amino-2- (p-aminophenyl) benzoxazole (DAMBO) and N-methyl-2-pyrrolidone (NMP) were added. After introduction and complete dissolution, pyromellitic dianhydride (PMDA) and maleic anhydride (MA) were introduced as shown in Table 1 and stirred for 48 hours at a reaction temperature of only 25 ° C. Then, a yellow and viscous polyamide acid solution (varnish) was obtained. Table 1 shows the solution properties of the varnish. Shown in

[Varnish production examples 2 to 6]
Hereinafter, according to the same procedure as in Production Example 1, a polyamic acid solution was prepared with the compounding ratio shown in Table 1, and the solution characteristics were evaluated. The results are shown in Table 1. Shown in

Example 1
The varnish obtained in Production Example 1 was applied onto an alkali-free glass substrate using an applicator, dried in an explosion-proof oven at 90 ° C. for 60 minutes, and then heated to 200 ° C. at 20 ° C./min. Hold at 200 ° C. for 30 minutes, then increase the temperature to 300 ° C. at 20 ° C./minute and hold for 15 minutes. A glass / polyimide laminate was obtained. The amount of varnish applied was adjusted by adjusting the amount of varnish applied so that the film thickness after drying and heat treatment was 20 μm.
The obtained glass / polyimide laminate was evaluated for heat resistance at 400 ° C. for 1 hour, appearance, alkali resistance, acid resistance, and solvent resistance. The results are shown in Table 2. Shown in The glass / polyimide laminate obtained in Example 1 was a good result without any polyimide film peeling from the glass and no blistering.

<< Examples 2-4, Comparative Examples 1-2 >>
Similarly, the glass / polyimide laminated body of Examples 2-4 was obtained using the varnish obtained in manufacture examples 2-4. Evaluation was performed in the same manner. The results are shown in Table 2. Shown in The glass / polyimide laminates obtained in Examples 2 to 4 had good results without any polyimide coating peeling from the glass and no blistering.
Similarly, the glass / polyimide laminates of Comparative Example 1 and Comparative Example 2 were obtained using the varnishes obtained in Production Example 5 and Production Example 6. Evaluation was performed in the same manner. The results are shown in Table 2. Shown in In Comparative Example 1, the obtained glass / polyimide laminate had a brittle film when the polyimide coating was peeled from the glass, making it difficult to measure the peel force. Moreover, it was judged that the glass / polyimide laminate obtained in Comparative Example 2 had extremely weak adhesive strength from glass to the polyimide coating and could not withstand the wet cleaning process in the process.

<Application example of ultra-thin device by peeling after circuit formation>
An ultrathin device was prepared using the glass / polyimide laminate obtained in Example 1. First, a SiN film was formed on the polyimide film of the laminate by a CVD method in order to prevent diffusion of impurities from the polyimide film, and a SiO2 film was further deposited thereon. Next, an a-Si film is deposited on the SiO2 film by a CVD method, and then the a-Si film in the channel portion is thinned by a dry etching method, and the substrate subjected to dehydrogenation is irradiated with an excimer laser to excimer. Laser annealing treatment was performed to change the a-Si film into a polysilicon film. Next, a gate insulating film is deposited on the polysilicon film, a gate electrode material is deposited on the gate insulating film and patterned to form a gate electrode, and then an impurity for forming a source / drain portion A TFT was formed by introducing impurities using an ion doping method. During the TFT formation process, the polyimide film did not change particularly so as to inhibit the process. The operation of the TFT of the obtained ultra-thin device was confirmed, and it was confirmed that it exhibited good switching characteristics.
An ultrathin device was prepared using the glass / polyimide laminate obtained in Example 2. First, a SiO film by a CVD method was formed as a base layer on the glass surface side of the laminate. Next, excimer laser annealing was performed by irradiating the dehydrogenated substrate with an excimer laser to change the a-Si film into a polysilicon film. Next, a gate insulating film is deposited on the polysilicon film, a gate electrode material is deposited on the gate insulating film and patterned to form a gate electrode, and then an impurity for forming a source / drain portion A TFT was formed by introducing impurities using an ion doping method. During the TFT formation process, the polyimide film did not change particularly so as to inhibit the process.
Similarly, using the glass / polyimide laminates obtained in Examples and Comparative Examples, TFTs are formed in the same manner, and the TFTs are peeled off from the glass substrate together with the polyimide film to obtain a film device. went. From the glass / polyimide laminate obtained in the example, a film device showing good TFT characteristics could be obtained, but in Comparative Example 1, the polyimide film was peeled off during the process, and the peeled part was damaged. I couldn't get a complete film device. In Comparative Example 2, the edge was peeled off during spray cleaning in the processing process, and the subsequent steps were stopped.

As described above, the polyimide precursor solution for producing a film device of the present invention forms a good film on the surface of a supporting substrate such as glass, and withstands stress such as heating and chemical use during film device processing. In addition, it is an article that provides an excellent film that can be promptly peeled off after completion of the process.
The polyimide precursor solution for film device production in the present invention is excellent in durability even in an environment where the temperature changes, and is durable even at high temperature exposure at the time of device formation, and has little expansion and contraction.・ Because stress is not applied to the semiconductor element and the difference in coefficient of linear expansion with the inorganic substrate is small, it is difficult to warp when forming a circuit at a high temperature on a laminate with the inorganic substrate. It is possible to create stable active devices, passive devices and interconnects, and since it is easy to create a flat surface with a small surface roughness compared to inorganic layers, it is easy to create fine interconnects and has an insulating property. It is extremely useful for creating electronic devices that have a circuit formed on a thin polyimide layer that has both flexibility and heat resistance, and has both useful adhesion and ease of peeling. Irumudebaisu a manufacturing polyimide precursor solution.
The polyimide precursor solution for film device production in the present invention can be applied to the following film devices. That is, power semiconductor elements, thin film transistors, sensors, solar cells, or logic circuit elements, more specifically, MEMS elements, light emitting elements, actuator elements, rectifier diodes, power transistors, power MOSFETs, insulated gate bipolar transistors ( IGBT), thyristor, gate turn-off thyristor (GTO), triac, microcrystalline silicon TFT, high-temperature polysilicon TFT, low-temperature polysilicon TFT, oxide semiconductor TFT, organic semiconductor TFT, strain gauge (strain gauge), load cell, semiconductor pressure Sensor, Photosensor, Photoelectric element, Photodiode, Display element, Liquid crystal display element, Electroluminescent element, Electrophoretic element, Electric rotating ball element, Electric rotating cylinder element, Magnetic sensor, Contact type temperature sensor, Ser Star temperature sensor, resistance temperature sensor temperature sensor, thermocouple temperature sensor, non-contact temperature sensor, radiation thermometer, microphone, ion concentration sensor, gas concentration sensor, displacement sensor, potentiometer, differential transformer displacement sensor, rotation angle sensor , Linear encoder, tachometer, rotary encoder, optical position sensor (PSD), ultrasonic distance meter, capacitance displacement meter, laser Doppler vibration speed meter, laser Doppler velocimeter, gyro sensor, acceleration sensor, seismic sensor, one-dimensional Image, linear image sensor, two-dimensional image, CCD image sensor, CMOS image sensor, electric field sensor, current sensor, voltage sensor, power sensor, infrared sensor, radiation sensor, humidity sensor, odor sensor Sir, flow sensor, tilt sensor, vibration sensor, time sensor, composite sensor, inkjet printer head, probe for scanning probe microscope, contactor for LSI prober, light spatial modulator for maskless exposure, optical integrated element, infrared sensor, For flow sensors, acceleration sensors, MEMS gyro sensors, RF MEMS switches, internal and external blood pressure sensors, video projectors using grating light valves, digital micromirror devices, etc., solar cells, logic circuits based on NAND, OR, etc. Can be used.

Claims (3)

Polyimide precursor used in the process of obtaining ultra-thin devices by obtaining polyimide film by applying polyimide precursor solution on inorganic substrate, drying and heat treatment, forming thin film device on polyimide film and then peeling off from inorganic substrate In the body solution, the polyimide precursor solution is a polyamic acid solution mainly composed of a solvent, aromatic tetracarboxylic acid anhydrides, dicarboxylic acid anhydrides, and a polyamide obtained from a diamine having a benzazole skeleton. Yes, the number of moles An of the carboxylic anhydride groups possessed by the aromatic tetracarboxylic acid anhydrides, the number of moles Bn of the carboxylic anhydride groups possessed by the dicarboxylic anhydrides, and the moles of the amino groups possessed by the diamines the number and Cn are film device manufacture, characterized by satisfying the following relationships (1) and a (2) at the same time Polyimide precursor solution.
0.90 ≦ Cn / (An + Bn) <1.0 (1)
0 ≦ Bn / An ≦ 0.05 (2)   The polyimide precursor solution for producing an ultrathin device according to claim 1, wherein the polyimide film has a linear expansion coefficient of -5 ppm / ° C to +8 ppm / ° C. A polyimide film is obtained by applying, drying and heat-treating a polyimide precursor solution on a glass substrate, and the peeling force of the polyimide film from the glass substrate when peeling from the glass substrate is 1.6 N / cm to 7. The polyimide precursor solution for producing an ultrathin device according to claim 1, which is 0 N / cm.