JP6878870B2 - Laminates, methods for manufacturing laminates and methods for manufacturing flexible devices - Google Patents

Description

The present invention relates to a laminate composed of a support layer made of an inorganic substance and a polyimide layer, a laminate having a device layer, a method for manufacturing the laminate, and a method for manufacturing a flexible device. Is.
More specifically, when forming a device made of a thin film such as a semiconductor element, a MEMS element, and a display element and requiring fine processing on the surface of a polyimide film, a substrate made of an inorganic substance that temporarily supports the polyimide film. It is an invention relating to a laminate used for manufacturing a flexible device which is bonded to a laminate and peeled off after device formation, and further relates to an invention relating to a method of manufacturing a flexible device using the laminate.
More specifically, by using a support made of a heat-resistant inorganic substance and a thin polyimide layer having heat resistance and insulating properties comparable to those of the inorganic substance and having a coefficient of linear expansion similar to that of the inorganic substance as constituent components. , Is an invention relating to a laminate usefully used for obtaining an electronic device having a delicate structure.

Display devices such as liquid crystal display devices and organic EL display devices are used for information display applications in various devices and equipment such as large displays such as televisions and small displays such as mobile phones, personal computers, and smartphones. As an example, in an organic EL display device, a thin film transistor (hereinafter referred to as TFT) is generally formed on a glass substrate which is a supporting base material, an electrode, a light emitting layer, and an electrode are sequentially formed, and finally a glass substrate, a multilayer thin film, or the like is separately formed. Made by airtight sealing.

Here, if the glass substrate, which is the supporting base material, can be replaced with a flexible resin base material from the conventional glass substrate, the display device can be made thinner, lighter, and more flexible, and the applications of the display device can be further expanded. We can expect to acquire a large market. However, the equipment for manufacturing a conventional display device is designed on the premise that a glass substrate, which is a rigid plate material, is used as a support, and a flexible film substrate cannot be handled. In order to deal with such problems, technological development has been carried out by various methods.

Non-Patent Document 1 discloses a method of manufacturing a device on a rigid substrate such as a glass substrate or a Si wafer substrate, and then peeling the device layer from the rigid substrate and transferring it to a film substrate. Such techniques have been studied for a relatively long time, but there are many cases where the device is damaged during transfer. This is because it is difficult to peel off the device layer from the rigid substrate during transfer.

Non-Patent Document 2 discloses a method of producing a device directly on a film by a Roll to Roll process. The Roll to Roll process is an ideal method for products that use a flexible and rewindable film material for the substrate, and in fact is practical for mass production of flexible printed wiring boards and film semiconductor packages such as TAB or COF. It has been transformed. However, in an application that requires high-definition microfabrication such as a display device, there is a problem that the device becomes extremely large and expensive because it is necessary to secure extremely high alignment accuracy in a large area.

In Non-Patent Document 3, a rigid substrate such as a glass substrate or a Si wafer substrate is used as a support, a polymer film layer is formed on the support, a device is formed on the polymer film, and then the polymer is formed from the rigid substrate. A method for obtaining a flexible device by peeling off a film device is disclosed. Such a process is an excellent method in that a device used for manufacturing a conventional display device or semiconductor device can be applied, but like the transfer method, there is a difficulty in the step of peeling the device layer from the support. First, in order to form a polymer film layer directly on a rigid support, it is necessary to apply, dry, and cure a polymer solution or a polymer precursor solution to the support, but empirically. The film layer formed by such a method tends to be relatively brittle, and there is a high risk of breakage during peeling. Further, it is difficult to control the adhesiveness between the support and the polymer film layer, and if the adhesive force is too strong, the risk of the film being damaged during peeling increases.

In order to deal with such a problem, a technique has been proposed in which a so-called peeling layer is formed on the surface of the support to control the adhesive force of the polymer film layer to be low and to avoid film breakage during peeling.
Patent Document 1 describes a substrate structure applied to a flexible electronic device, which includes a support substrate, a release layer covering the support substrate with a first area, and a flexible layer covering the release layer and the carrier with a second area. Disclosed is a technique for forming a substrate structure, which includes a substrate, wherein the second area is larger than the first area, and the flexible substrate has a degree of adhesion higher than the degree of adhesion of the release layer to the carrier. As a specific example, after forming a first layer made of parylene or cyclic olefin on a glass substrate, a polyimide precursor or a polyimide resin solution is applied, dried, and cured to directly use a polyimide film as a second layer on a support. The technique of forming and then forming a device and peeling between the first layer and the second layer is exemplified. That is, this is an example in which the first layer, parylene or cyclic olefin resin layer, is used as the release layer. Since the heat resistance of parylene or cyclic olefin resin is insufficient in this technology, the polyimide resin that can be used is limited to the type that can be formed at low temperature, and high temperature cannot be used even in the device forming process.

Patent Document 2 describes a step of forming a resin film (a) on an upper layer of a support substrate, a step of forming a semiconductor element on an upper layer of a resin film (a), and a step of forming a resin film (a) on which a semiconductor element is formed. A method for manufacturing a semiconductor device including a step of peeling a substrate. The resin film (a) has a film thickness of 1 μm or more and 30 μm or less, and a visible light transmittance of 80% or more and a wavelength of 400 nm or more and 800 nm or less. Yes, the 3% weight loss temperature is 300 ° C. or higher, the melting point is 280 ° C. or higher, the glass transition temperature is 250 ° C. or higher, and the resin film (a) is a poly represented by the following formula (I). A method for producing the semiconductor device including benzoxazole and at least one polymer material selected from the group consisting of a polyimide having an alicyclic structure represented by the following formula (v) is disclosed, which is more preferable. Describes a method for manufacturing a semiconductor device, further including a step of forming a resin layer (b) between a support substrate and a resin film (a). That is, the resin layer (b) functions here as a release layer. The polymer film layer used in the present technology is a so-called transparent heat-resistant film, which is a polymer film that satisfies both colorlessness and heat resistance. Such types of polymeric materials become noticeable in color when exposed to processes above 300 ° C. Moreover, since the coefficient of linear expansion is relatively large, there is often a problem in flatness after device formation. When polybenzoxazole is used as a film material, the film formation temperature is extremely high, so that the polymer material that can be used for the release layer is extremely limited. Furthermore, since the film made of polybenzoxazole resin is brittle, it is a flexible device. It cannot be said that it is suitable as a substrate for.

Patent Document 3 describes a laminated film in which a first polyimide layer and a second polyimide layer are directly laminated and a support, and a first polyimide layer surface of the laminated film and one surface of the support via an adhesive layer. After bonding, a predetermined display portion is formed on the laminated film, and then separated at the interface between the first polyimide layer and the second polyimide layer, and the display portion is formed on the polyimide base material composed of the second polyimide layer. Disclosed is a method of manufacturing a display device, which comprises obtaining a display device provided with the above. That is, a film having a two-layer structure composed of a first polyimide layer that functions as a release layer and a second polyimide layer that serves as a flexible substrate is produced in advance, and then the release layer and the support substrate are bonded to each other for release. It is a technology that realizes a structure that sandwiches layers.
The first difficulty in the present technology is that it is necessary to bond a film that functions as a release layer, that is, a film having poor adhesiveness, to a support substrate. In the case of a peeling layer that can be relatively easily adhered to the support, the adhesiveness between the flexible substrate and the flexible substrate is also high, which causes difficulty in the essential peeling process. Furthermore, in the case of a release layer having poor adhesiveness to the support, the adhesiveness between the release layer and the flexible substrate is also low, so that the release layer and the flexible substrate are separated before being bonded to the support. I have to say that the risk is very high.

Japanese Patent No. 4834758 Japanese Patent No. 54088848 Japanese Patent No. 5898328

T.Shimoda el al., In IEDM Tech. Dig., Pp289-292, (1999) Mitani et al., Jpn. J. Appl. Phys. 47, pp8708, (2008) Ian French el al., SID 05 Digest, pp1634-1637, (2005)

As a method of using a rigid substrate as a support, forming a device layer on a film layer provided on the support, and then peeling the device layer to obtain a flexible device, a conventional method for manufacturing a rigid device and a manufacturing device are diverted. Since it can be done, it has attracted attention as an advantageous method for industrial production.
Manufacture of a high-definition device that has a complicated multi-layer structure and requires precise alignment is flexible and has poor shape retention, and it is highly difficult to use a film substrate that is inferior in dimensional stability as it is. It can be said that the method of using such a rigid support together is a highly realistic method.
However, in order to realize such a technology, the flexible substrate material is temporarily fixed to a rigid and robust substrate having excellent dimensional stability, and in this peeling method after the device is created, the flexible substrate and the support substrate are peeled off smoothly. It is necessary to realize a laminate with a flexible substrate / support substrate that can be carried out in a straightforward manner and that does not peel off during the device manufacturing process.

However, in the case of manufacturing a semiconductor device in general, in the CVD method used for forming a semiconductor layer, the crystallinity of the semiconductor layer is generally higher and the adhesion to the substrate is also higher when CVD is performed under high temperature conditions. Are known. However, in the conventionally devised laminated body of the flexible substrate and the inorganic support, it is difficult to maintain the adhesion between the support and the flexible substrate at a high temperature. When a material with low heat resistance is used for the flexible substrate material itself, when an adhesive or a release layer with low heat resistance is used, thermal deterioration of the adhesive or the release layer occurs, and fine dust is generated due to carbonization. Alternatively, when decomposition gas is generated to generate blister between the support and the flexible substrate, or when the adhesive force cannot be maintained and the product peels off during the device processing process, or conversely, between the flexible substrate and the support or the release layer. There have been various problems such as when the adhesive force of the flexible substrate is strengthened by a thermochemical reaction and it becomes difficult to peel off the flexible substrate.

A polyimide film can be used as a heat-resistant flexible substrate, and a polyimide film having a heat resistance of about 450 ° C. can be realized by selecting the resin composition of the polyimide and the polyimide manufacturing process. If such a polyimide film is used for a flexible substrate, carbonization and gas generation of the flexible substrate can be suppressed. However, when the process temperature exceeds 470 ° C, preferably exceeds 490 ° C, and more preferably exceeds 500 ° C, there may be a problem that it becomes difficult to separate the flexible substrate and the support substrate. is there. When the temperature exceeds 470 ° C. or higher, preferably 490 ° C. or higher, and more preferably 500 ° C. or higher, both the thermal decomposition and reimidization processes of polyimide proceed simultaneously in such a temperature range, and active groups generated during the reaction are generated. It is presumed that a chemical reaction occurs with the active groups existing on the surface of the supporting substrate such as glass and silicon wafer. It is very difficult to control the chemical reaction at such a high temperature.
As one of the solutions in such a case, a method of irradiating a high-energy ray such as an ultraviolet laser from the support substrate side to break the bond between the easily sible substrate and the support substrate is known. However, it is expensive, and when it is applied to a large area, the front surface must be scanned, which increases the process time and poses a big problem in terms of cost.

A method of applying a polyimide precursor to an inorganic substrate such as a glass substrate, drying it, heating it to imidize it, and using the obtained polyimide layer as a flexible substrate has been tried for a long time, but it can be obtained by such a process. In the manufacturing process, one side of the polyimide film is sealed with a glass substrate, and the divergence of water generated by the imidization reaction of the solvent component and reaction by-products, especially the amic acid present in the precursor, is on the film surface. As a result, inhomogeneity occurs in the film film thickness direction, the physical properties are inclined, warpage occurs due to internal stress, and the film itself is brittle and has low strength. .. Due to these problems, the polyimide layer thus obtained is not satisfactory as a flexible substrate.

As a result of diligent research to solve the above problems, the present inventors have conducted a second resin in a state where the first resin layer and the second resin layer made of the polyimide resin layer are laminated on the support. A flexible device provided with a device on a flexible resin base material composed of a second resin layer by forming a predetermined device on the layer and then separating the device at the interface between the first resin layer and the second resin layer. We have found that can be obtained extremely efficiently, and have completed the present invention.
That is, the present invention has the following configuration.

[1] In a laminated body including an inorganic substrate, a first polyimide layer adjacent to the inorganic substrate, and a second polyimide layer located on the opposite side of the first polyimide layer from the inorganic substrate.
The first polyimide layer is a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing a diamine having at least a benzoxazole skeleton.
The film thickness unevenness of the second polyimide layer is 5% or less, and the tensile breaking strength is 200 MP or more.
Adhesive strength between the inorganic substrate and the first polyimide layer is F1,
The adhesive strength between the first polyimide layer and the second polyimide layer is F2,
When, F1 ≧ 2 × F2, and
Set the thermal decomposition temperature of the first polyimide layer to Temp 1,
Set the thermal decomposition temperature of the second polyimide layer to Temp2,
When
Temp1 ≧ Temp2
A laminate characterized by being.
[2] When the average film thickness of the first polyimide layer is T and the undercut of the edge portion of the first polyimide layer is U.
U> T
The laminate according to [1], which is characterized in that.
[3] The laminate according to [1] or [2], wherein a silane coupling agent layer is provided between the inorganic substrate and the first polyimide layer.
[4] The laminate according to any one of [1] to [3], wherein the device is formed on the side of the second polyimide layer opposite to the first polyimide layer [5]. The laminate according to any one of [1] to [4], wherein the device includes an electrical wiring layer.
[6] The laminate according to any one of [1] to [5], wherein the device includes a semiconductor element.
[7] The laminate according to any one of [1] to [6], wherein the device includes a gas barrier layer.
[8] At least, a step of applying a solution of a polyimide resin to be a first polyimide layer or a precursor solution to an inorganic substrate and forming a first polyimide layer by a process involving heating, and then a first polyimide. It is characterized by including a step of forming a second polyimide layer by laminating a polyimide film having a film thickness unevenness of 5% or less and a tensile breaking strength of 90 MPa or more on the surface of the layer opposite to the inorganic substrate. The method for producing a laminate according to any one of [1] to [7].
[9] A device formed on the second polyimide layer is obtained by peeling between the first polyimide layer and the second polyimide layer of the laminate according to any one of [4] to [7]. A method for manufacturing a flexible device.

Further, the present invention preferably has the following constitution. [10] The second polyimide layer is a film of a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing a diamine having at least a benzoxazole skeleton. The laminate according to any one of [1] to [7], the method for producing a laminate according to [8], and the method for producing a flexible device according to [9].
[11] The second polyimide layer is a film of a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing a diamine having at least an ether bond in the molecule [1] to [1]. 7], the method for producing the laminate according to [8], and the method for producing a flexible device according to [9].
[12] One of [1] to [7], wherein the second polyimide layer is a film of a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing at least phenylenediamine. The laminate according to the above, the method for producing the laminate according to [8], and the method for producing a flexible device according to [9].
[13] The laminate according to any one of [1] to [7], wherein the second polyimide layer is a film of a condensate of a biphenyltetracarboxylic dianhydride and an aromatic diamine. , The method for producing a laminate according to [8], and the method for producing a flexible device according to [9].
[14] The laminate according to any one of [1] to [7] and [10] to [13], wherein the silicon oxide component contained in the first polyimide layer is 1000 ppm or less. 8] The method for manufacturing a laminate, and [9] a method for manufacturing a flexible device.
[15] The laminate according to any one of [1] to [7] and [10] to [13], wherein the silicon oxide component contained in the second polyimide layer is 1000 ppm or less. 8] The method for manufacturing a laminate, and [9] a method for manufacturing a flexible device.
[16] One of [1] to [7] and [10] to [13], wherein the area of the first polyimide layer covering the inorganic substrate is larger than the area of the second polyimide layer. The laminate according to the above, the method for producing the laminate according to [8], and the method for producing a flexible device according to [9].
[17] The area covered by the first polyimide layer covering the inorganic substrate is larger than the area of the second polyimide layer, and the second polyimide layer has an area in direct contact with the inorganic plate [17]. The laminate according to any one of 1] to [7], [10] to [13], the method for producing the laminate according to [8], and the method for producing a flexible device according to [9].
[18] The step of laminating a polyimide film having a film thickness unevenness of 5% or less and a tensile breaking strength of 90 MPa or more on the surface of the first polyimide layer opposite to the inorganic substrate includes the following steps. The method for producing a laminate according to [8] and the method for producing a flexible device according to [9].
-A step of performing a silane coupling treatment on the first polyimide layer side of the inorganic substrate on which the first polyimide layer is formed.
-A step of laminating a polyimide film to be a second polyimide layer on a surface treated with a silane coupling agent.
-The process of pressing the polyimide film against the inorganic substrate side,
[19] The method for producing a laminate according to [8] and [18], which comprises performing an activation treatment on the side of the polyimide film to be adhered to the first polyimide layer, [9] and [18]. ] The method for manufacturing a flexible device described in.

By using the laminate of the present invention, even when a semiconductor thin film is formed on a flexible substrate which is a second polyimide layer by a CVD method or the like, a good thin film can be formed without the flexible substrate peeling off from the support side. Therefore, it is possible to form a device including an electric wiring, a semiconductor element, a gas barrier layer, and the like on a flexible substrate made of a second polyimide layer.

In the present invention, the condensate of an aromatic tetracarboxylic dianhydride used as the first polyimide layer and a diamine containing a diamine having at least a benzoxazole skeleton has extremely high chemical durability. Have. In other words, it has poor reactivity with other compounds. Therefore, a chemical reaction is unlikely to occur between the second polyimide layer and the second polyimide layer which is in direct contact with the first polyimide layer, and the adhesive force between the two is low.
On the other hand, since the first polyimide layer and the second polyimide layer are in close contact with each other without a gap, in addition to the so-called vacuum adhesion effect, they are bonded by the van der Waals force generated because they are extremely close to each other. These adhesive forces prevent peeling during the device processing process, and the device can be peeled together with the flexible substrate after the device is formed.

In the present invention, the condensate of the aromatic tetracarboxylic acid dianhydride used as the first polyimide layer and the diamine containing a diamine having at least a benzoxazole skeleton has extremely high heat resistance and an inorganic substrate. Since it has a coefficient of linear expansion as low as that of the second polyimide layer, it can withstand the thermal history when the device is formed on the second polyimide layer without any problem, and after the second polyimide layer is peeled off, it can withstand. It can be reused multiple times.

In the present invention, particularly when a structure is formed between the inorganic substrate and the first polyimide layer via a silane coupling agent layer, the inorganic substrate and the first polyimide layer are more strongly adhered to each other, so that the second polyimide is used. When the layer is peeled off, the peeling error of peeling from the first polyimide layer can be further reduced. On the other hand, the surface hardness of the first polyimide layer is lower than that of the inorganic substrate, and scratches and the like increase on the surface due to multiple recyclings, which eventually adversely affects the quality of the second polyimide layer. .. In that case, it becomes necessary to peel off the first polyimide layer and form the first polyimide layer again. In the present invention, since a polyimide resin having high heat resistance is used for the first polyimide layer, the temperature is 520 ° C. or higher in a laminated state consisting of an inorganic substrate and the first polyimide layer, that is, in a state where the second polyimide layer is peeled off. By heating in a temperature range of preferably 700 ° C. or lower, more preferably 620 ° C. or lower, the silane coupling agent layer that greatly contributes to adhesion is thermally decomposed, while the first polyimide layer is formed. It can be left as a layer. In such a case, the first polyimide layer can be peeled off from the inorganic substrate without residue, and the inorganic substrate can be easily recycled. When the heat resistance of the polyimide resin constituting the first polyimide layer is low, carbonization of the polyimide layer and scorching on the surface of the inorganic substrate occur, and it is often difficult to reuse the inorganic plate.

In the present invention, by increasing the undercut of the edge portion of the first polyimide layer, it is possible to significantly reduce the peeling accident of the first polyimide layer during the device processing process. It is understood that such an effect is because the internal stress at the edge portion of the polyimide layer tends to bite into the inorganic substrate at the edge portion of the polyimide layer, in addition to simply reducing the catching at the edge. That is, when the polyimide precursor is applied, dried, and cured on the inorganic substrate, the molecular orientation of the coating film surface layer is more likely to proceed than the inside of the coating film, so that the CTE inside the coating film is larger than that inside the coating film surface layer. become. Since the curing reaction of polyimide is generally performed at a relatively high temperature, when cooled after curing, the shrinkage inside the coating film having a large CTE becomes large, so that the stress in the layer is in the direction in which the inner side draws in the surface layer having a small CTE. It acts on.

FIG. 1 is a schematic view showing a cross-sectional structure of the laminated body of the present invention. FIG. 2 is a schematic view illustrating how to obtain the undercut of the present invention. FIG. 3 shows an arrangement in the present invention in which the portion where the first polyimide layer covers the inorganic substrate is larger than the portion covered by the second polyimide layer and the second polyimide does not come into direct contact with the inorganic plate. It is a top view which shows. FIG. 4 shows an arrangement in the present invention in which the area covered by the first polyimide layer covering the inorganic substrate is larger than the area of the second polyimide layer and the second polyimide layer is in direct contact with the inorganic plate. It is a top view which shows an example. Figure 5. Is a schematic diagram when a device is formed on the second polyimide layer.

1: First polyimide layer 3: Second polyimide layer 5: Device 10: Support (inorganic substrate)

In the laminate of the present invention, an inorganic substrate is used as the support substrate. The inorganic substrate is a plate-like material made of an inorganic substance, and examples thereof include a glass plate, a ceramic plate, a semiconductor wafer, and a metal plate. Further, a composite substrate in which two or more kinds selected from a glass plate, a ceramic plate, a semiconductor wafer, and a metal plate are laminated can also be used. Further exemplifying a complex in which one or more materials selected from glass, ceramics and metals are powder-dispersed in other inorganic or organic materials. Further, a substrate material having a fiber reinforced composite structure in which one or more fibrous substances selected from glass, ceramics and metals are compounded in another inorganic material or an organic material can be exemplified.

Examples of the glass used as the substrate material including the glass plate and the glass which are the inorganic substrates in the present invention include quartz glass, high silicate glass (96% silica), soda lime glass, lead glass, aluminoborosilicate glass, and borosilicate glass. (Pylex (registered trademark)), borosilicate glass (non-alkali), borosilicate glass (microsheet), aluminosilicate glass and the like can be exemplified. In the present invention, among these, those having a linear expansion coefficient of 5 ppm / K or less are particularly desirable, and if it is a commercially available product, "Corning (registered trademark) 7059" or "Corning" manufactured by Corning Inc., which is a glass for a liquid crystal display element. It is desirable to use "(registered trademark) 1737", "EAGLE XG", "AN100" manufactured by Asahi Glass, "OA10G" manufactured by Nippon Electric Glass, "AF32" manufactured by SCHOTT, and the like.

The ceramic plate which is the inorganic substrate in the present invention includes alumina, mulite, aluminum nitride, silicon carbide, silicon nitride, boron nitride, crystallized glass, cordurite, lysia bright stone, Pb-BSG + CaZrO ₃ + Al ₂ O ₃ , Crystallized glass + Al ₂ O ₃ , crystallized Ca- borosilicate glass, borosilicate glass + quartz, borosilicate glass + Al ₂ O ₃ , Pb + borosilicate glass + Al ₂ O ₃ , glass ceramics, ceramics for substrates such as zero-dure materials, Titanium oxide, strontium titanate, calcium titanate, magnesium titanate, alumina, magnesia, steatite, BaTi ₄ O ₉ , BaTi ₄ O ₉ + CaZrO ₃ , BaSrCaZrTIO ₃ , Ba (TiZr) O ₃ , PMN-PT and PFN- capacitor materials such as _{PFW, PbNb 2 O 6, Pb} 0.5 Be 0.5 Nb 2 O 6, PbTiO 3, BaTiO 3, PZT, 0.855PZT-95PT-0.5BT, 0.873PZT-0.97PT-0.3BT, a piezoelectric material such as PLZT An example thereof is a ceramic plate made of one or more materials selected from the above.

Examples of the metal material constituting the metal plate in the present invention include single element metals such as W, Mo, Pt, Fe, Ni, and Au, inconel, monel, mnemonic, carbon copper, Fe—Ni based invar alloy, and superinvar alloy. Such as alloys are included. Further, a multilayer metal plate formed by adding another metal layer or a ceramic layer to these metals is also included. In this case, if the overall CTE with the additional layer is low, Cu, Al, or the like is also used for the main metal layer. The metal used as the additional metal layer is limited as long as it has properties such as strong adhesion to the polyimide film, no diffusion, and good chemical resistance and heat resistance. Although not, chromium, nickel, TiN, and Mo-containing Cu are preferred examples.

As the semiconductor wafer in the present invention, a silicon wafer, a silicon carbide wafer, a compound semiconductor wafer and the like can be used, and the silicon wafer is an n-type wafer obtained by processing single crystal or polycrystal silicon on a thin plate. Alternatively, all of p-type doped silicon wafers, intrinsic silicon wafers, etc. are included, and silicon wafers in which a silicon oxide layer and various thin films are deposited on the surface of the silicon wafer are also included, in addition to the silicon wafer. , Germanium, silicon-germanium, gallium-arsenic, aluminum-gallium-indium, nitrogen-phosphorus-arsenide-antimony, SiC, InP (indium phosphorus), InGaAs, GaInNAs, LT, LN, ZnO (zinc oxide) and CdTe (cadmium). Semiconductor wafers such as tellurium) and ZnSe (zinc selenium), compound semiconductor wafers, and the like can be used.

The inorganic substrate serving as the support is subjected to activation treatment such as UV ozone treatment, vacuum plasma treatment, atmospheric pressure plasma treatment, corona treatment, flame treatment, itro treatment, UV ozone treatment, and exposure treatment to an active gas. Can be done. These treatments mainly have a cleaning effect of removing adhering contaminants such as organic substances on the surface of the inorganic substrate, and an effect of activating the surface of the inorganic substrate to improve the adhesiveness with the first polyimide layer.

The polyimide in the present invention is a multimer due to an imide bond. Generally, polyimide is obtained as a condensate of tetracarboxylic dianhydride and diamine. As a general method for producing polyimide, a polyamic acid (polyimide precursor) solution obtained by reacting a tetracarboxylic acid dianhydride with a diamine in a solvent is applied to a support and dried to obtain a precursor film. Further, there is known a method of causing an imidization reaction by the action of heating or a catalyst to convert it into polyimide. When forming a polyimide into a film, a method of peeling the precursor film from the support and imidizing it is common. Further, in the application of coating the support, a method of imidization without peeling is also known. A method of applying a precursor solution on a support, drying it, and imidizing it on the support is being studied for practical use in applications where a polyimide film is used as a substrate for a flexible device.

As the tetracarboxylic dianhydride in the present invention, aromatic tetracarboxylic dianhydride and alicyclic tetracarboxylic dianhydride can be preferably used. From the viewpoint of heat resistance, aromatic tetracarboxylic dianhydride is preferable, and from the viewpoint of light transmission, alicyclic tetracarboxylic dianhydride is preferable. The tetracarboxylic dianhydride may be used alone or in combination of two or more.

The aromatic tetracarboxylic dianoxide in the present invention includes pyromellitic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3. ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) ) Phenyl] Propanic acid anhydride and the like can be mentioned. In the present invention, it is preferable to use pyromellitic dianhydride.

Examples of the alicyclic tetracarboxylic acids in the present invention include fats such as cyclobutanetetracarboxylic acid, 1,2,4,5-cyclohexanetetracarboxylic acid, and 3,3', 4,4'-bicyclohexyltetracarboxylic acid. Examples include cyclic tetracarboxylic dians and acid anhydrides thereof. Among these, dianhydrides having two anhydride structures (eg, cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3', 4,4 '-Bicyclohexyltetracarboxylic dianhydride, etc.) is suitable. The alicyclic tetracarboxylic acids may be used alone or in combination of two or more.
When transparency is important, the alicyclic tetracarboxylic acids are, for example, preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more of all tetracarboxylic acids.

The diamines in the present invention are not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines and the like usually used for polyimide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferable, and among the aromatic diamines, aromatic diamines having a benzoxazole structure can be used. When aromatic diamines having a benzoxazole structure are used, it is possible to develop high elastic modulus, low coefficient of thermal expansion, and low linear expansion coefficient as well as high heat resistance. The diamines may be used alone or in combination of two or more.

Among the amines in the present invention, examples of aromatic amines include 2,2'-dimethyl-4,4'-diaminobiphenyl and 1,4-bis [2- (4-aminophenyl) -2-propyl. ] Benzene (bisaniline), 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 4,4'-bis (4) -Aminophenoxy) biphenyl, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, 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'-diaminodiphenyl ether, 3, 4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfone, 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- (4- (4- (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-aminophenoki) Si) 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-methylphenyl] 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] Sulfoxide, 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- (3-aminophenoxy) phenyl] Aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3- (3-)3-" Aminophenoxy) phenyl] sulfoxide, 4,4'-bis [3- (4-aminophenoxy) be Nzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4, 4'-bis [4- (4-amino-α, α-dimethylbenzyl) 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'-phenoxybenzophenone, 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) benzene, 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, and some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine are halogen atoms, carbon. Substituted with an alkyl group or alkoxyl group of number 1 to 3, a cyano group, or an alkyl group having 1 to 3 carbon atoms or an alkoxyl group in which a part or all of the hydrogen atoms of the alkyl group or the alkoxyl group are substituted with halogen atoms. Examples thereof include aromatic diamines that have been used.

Examples of the aliphatic diamines in the present invention include 1,2-diaminoethane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,8-diaminooctane and the like. ..
Examples of the alicyclic diamines in the present invention include 1,4-diaminocyclohexane and 4,4'-methylenebis (2,6-dimethylcyclohexylamine).

Examples of diamines having a benzoxazole structure in the present invention include 5-amino-2- (p-aminophenyl) benzoxazole, 6-amino-2- (p-aminophenyl) benzoxazole, and 5-amino-2. -(M-Aminophenyl) benzoxazole, 6-amino-2- (m-aminophenyl) benzoxazole, 2,2'-p-phenylenebis (5-aminobenzoxazole), 2,2'-p-phenylene Bis (6-aminobenzoxazole), 1- (5-aminobenzoxazole) -4- (6-aminobenzoxazole) benzene, 2,6- (4,4'-diaminodiphenyl) benzo [1,2 -D: 5,4-d'] bisoxazole, 2,6- (4,4'-diaminodiphenyl) benzo [1,2-d: 4,5-d'] bisoxazole, 2,6- (3) , 4'-diaminodiphenyl) benzo [1,2-d: 5,4-d'] bisoxazole, 2,6- (3,4'-diaminodiphenyl) benzo [1,2-d: 4,5- d'] bisoxazole, 2,6- (3,3'-diaminodiphenyl) benzo [1,2-d: 5,4-d'] bisoxazole, 2,6- (3,3'-diaminodiphenyl) Benzoxazole [1,2-d: 4,5-d'] bisoxazole and the like can be mentioned.

The present invention is a laminate including an inorganic substrate, a first polyimide layer adjacent to the inorganic substrate, and a second polyimide layer located on the opposite side of the first polyimide layer from the inorganic substrate.
The inorganic plate acts as an overall support.
In the present invention, it is essential that the first polyimide layer is a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing a diamine having at least a benzoxazole skeleton.

In the present invention, the first polyimide layer is provided close to the inorganic substrate and has an action as a so-called release layer. That is, the first polyimide layer is strongly adhered to the inorganic substrate, and is weakly adhered to the second polyimide layer. When the adhesive strength between the inorganic substrate and the first polyimide layer is F1 and the adhesive strength between the first polyimide layer and the second polyimide layer is F2, F1 ≧ 2 × F2 in the present invention. It is indispensable. That is, the adhesive strength between the inorganic substrate and the first polyimide layer must be at least twice the adhesive strength between the first polyimide layer and the second polyimide layer. Here, the adhesive strength is the so-called 90-degree peel strength. In the present invention, it is more preferable that F1 ≧ 3 × F2, and it is still more preferable that F1 ≧ 4 × F2. It is easily understood from the action of the first polyimide layer as a release layer that it is preferable that the adhesive strength between the two is large.
Further, in the present invention, it is essential that the relationship of Temp1 ≧ Temp2 is established when the thermal decomposition temperature of the first polyimide layer is Temp1 and the thermal decomposition temperature of the second polyimide layer is Temp2. That is, it is essential that the thermal decomposition temperature of the first polyimide layer is the same as or higher than the thermal decomposition temperature of the second polyimide layer, and it is preferable that there is a difference of 4 ° C. or more, and a difference of 8 ° C. or more. It is preferable that there is a difference of 12 ° C. or more. Here, the thermal decomposition temperature is a 5% weight reduction temperature obtained under the condition of TGA in an air atmosphere, 1 atm, and a heating rate of 10 ° C./min.

The film thickness of the first polyimide layer in the present invention is not particularly limited, but is preferably 0.5 μm to 200 μm, and more preferably 3 μm to 10 μm. If it is 0.5 μm or less, it is difficult to control the film thickness, and there is a possibility that a part where the polyimide layer is missing may be formed. Therefore, it may be difficult to peel off the second polyimide layer. If it is 200 μm or more in one step, it takes time to prepare the film, and it may be difficult to control the film thickness unevenness. The film thickness unevenness of the first polyimide layer is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. This is not the case when the support substrate incorporates a device for increasing the surface roughness to enhance the adhesiveness between the support substrate and the first polyimide layer.

As the second polyimide layer of the present invention, a film of a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing a diamine having at least a benzoxazole skeleton can be used.
Further, in the present invention, as the second polyimide layer, a film of a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing a diamine having an ether bond in the molecule can be used.
Furthermore, in the present invention, as the second polyimide layer, a film of a condensate of an aromatic tetracarboxylic dianhydride and a diamine containing at least phenylenediamine can be used.
Further, in the present invention, a film of a condensate of biphenyltetracarboxylic dianhydride and aromatic diamine can be used as the second polyimide layer.

The film of the condensate of the tetracarboxylic dianhydride and the diamine of the present invention, that is, the polyimide film can be obtained by a solution film forming method. In the polyimide solution film formation method, a stainless steel roll or endless belt or a polymer film such as PET is used as a long or endless support, and a polyimide resin precursor solution is applied onto the support. After drying, it is peeled off from the support to form a polyimide precursor film, preferably both ends of the film are gripped with clips or pins and conveyed, and further heat treatment is applied to chemically react the polyimide precursor with polyimide to make the polyimide. This is a method of obtaining a film. The polyimide film obtained by using such a method has a film thickness unevenness of 5% or less, preferably 3.6% or less, more preferably 2.4% or less, and a tensile breaking strength of 90 MPa or more, preferably 180 MPa or more. A polyimide film of 350 MPa or more, more preferably 450 MPa or more is more preferable.

In the present invention, it is possible to impregnate the polyimide with an inorganic substance in order to adjust the properties of the polyimide layer, but it should be kept to the minimum necessary. In the present invention, it is preferable to control the silicon oxide component contained in the first polyimide layer to be 1000 ppm or less.

In the present invention, it is preferable to control the silicon oxide component contained in the second polyimide layer to be 1000 ppm or less. In particular, in the second polyimide layer, it is desirable to reduce the inorganic component as much as possible, preferably 800 ppm or less, more preferably 600 ppm or less, still more preferably 400 ppm or less. The addition of unnecessary inorganic components may cause protrusions on the surface of the second polyimide layer, which may hinder the formation of particularly fine electronic devices on the second polyimide layer.

The film thickness of the second polyimide layer in the present invention is not particularly limited, but is preferably 1 μm to 200 μm, more preferably 2 to 90 μm, still more preferably 3 μm to 55 μm, and even more preferably. Is 3 to 15 μm.

In the present invention, when the average film thickness of the first polyimide layer is T and the undercut of the edge portion of the first polyimide layer is U.
U> T
Is preferable. Here, U is the undercut [μm], and T is the average film thickness [μm] of the first polyimide layer. The average film thickness is an average value of 10 randomly selected points in the first polyimide layer. The film thickness can be measured with a micrometer instead of a stylus meter when the second polyimide layer can be removed. When it is difficult to remove the second polyimide layer, the measurement is performed using an SEM image of the cross section of the laminated body.
In the present invention, by increasing the undercut of the edge portion of the first polyimide layer, it is possible to significantly reduce the peeling accident of the first polyimide layer during the device processing process. This is because, in addition to simply reducing the catching at the edge, the internal stress at the edge portion of the polyimide layer tends to bite into the inorganic substrate at the edge portion of the polyimide layer. When the polyimide precursor is applied, dried, and cured on the inorganic substrate, the molecular orientation of the coating film surface layer is more likely to proceed than the inside of the coating film, so that the CTE inside the coating film is larger than that inside the coating film surface layer. .. Since the curing reaction of polyimide is generally performed at a relatively high temperature, when cooled after curing, the shrinkage inside the coating film having a large CTE becomes large, so that the stress in the layer is in the direction in which the inner side draws in the surface layer having a small CTE. It acts on.
The undercut in the present invention is preferably U> 1.5 × T, preferably U> 2.4 × T, and more preferably U> 3.2 × T.

As the adhesive for adhering the inorganic substrate which is the support and the first polyimide layer in the present invention, a known adhesive or adhesive such as silicone resin, epoxy resin, acrylic resin, or polyester resin is used. Can be done. However, the preferable adhesive means in the present invention is an extremely thin adhesive means having an adhesive / adhesive layer having a film thickness of 5 μm or less, or preferably an adhesive means that does not substantially use an adhesive / adhesive.
In the present invention, a method using a silane coupling agent can be used as such an adhesive means. That is, in the present invention, it is preferable to have a silane coupling agent layer between the inorganic substrate and the first polyimide layer.
The silane coupling agent in the present invention refers to a compound that physically or chemically intervenes between the inorganic plate and the first polyimide layer and has an action of enhancing the adhesive force between the two.
Preferred specific examples of the silane coupling agent include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2- ( Aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, 2- (3,4-Epoxycyclohexyl) Ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, vinyltricrolsilane, Vinyl trimethoxysilane, vinyl triethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycid Xypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-Acryloxipropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane , 3-Chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanoxidetriethoxysilane, tris- (3-trimethoxy) Cyrilpropyl) isocyanurate, chloromethylphenetyltrimethoxysilane, chloromethyltrimethoxysilane, aminophenyltrimethoxysilane, aminophenetyltrimethoxysilane, aminophenylaminomethylphenetyltrimethoxysilane, hexamethyldisilazane and the like.

In addition to the above, silane coupling agents that can be used in the present invention include n-propyltrimethoxysilane, butyltrichlorosilane, 2-cyanoethyltriethoxysilane, cyclohexyltrichlorosilane, decyltrichlorosilane, diacetoxydimethylsilane, and diacetoxydimethylsilane. Ethoxydimethylsilane, dimethoxydimethylsilane, dimethoxydiphenylsilane, dimethoxymethylphenylsilane, dodecyllichlorosilane, dodecyltrimethoxylan, ethyltrichlorosilane, hexyltrimethoxysilane, octadecyltriethoxysilane, octadecyltrimethoxysilane, n-octyltrichlorosilane , N-octyltriethoxysilane, n-octyltrimethoxysilane, triethoxyethylsilane, triethoxymethylsilane, trimethoxymethylsilane, trimethoxyphenylsilane, pentyltriethoxysilane, pentyltrichlorosilane, triacetoxymethylsilane, trichloro Hexilsilane, trichloromethylsilane, trichlorooctadecylsilane, trichloropropylsilane, trichlorotetradecylsilane, trimethoxypropylsilane, allyltrichlorosilane, allyltriethoxysilane, allyltrimethoxysilane, diethoxymethylvinylsilane, dimethoxymethylvinylsilane, trichlorovinylsilane , Triethoxyvinylsilane, vinyltris (2-methoxyethoxy) silane, trichloro-2-cyanoethylsilane, diethoxy (3-glycidyloxypropyl) methylsilane, 3-glycidyloxypropyl (dimethoxy) methylsilane, 3-glycidyloxypropyltrimethoxysilane, Etc. can also be used.

Further, other alkoxylans such as tetramethoxysilane and tetraethoxysilane may be appropriately added to the silane coupling agent. Further, the reaction is slightly carried out by adding mixing and heating operations, including the case where other alkoxylans such as tetramethoxysilane and tetraethoxysilane are appropriately added to the silane coupling agent, and the case where they are not added. You may use it after proceeding.

Among such silane coupling agents, the silane coupling agent preferably used in the present invention is preferably a silane coupling agent having a chemical structure having one silicon atom per molecule.
In the present invention, particularly preferable silane coupling agents include N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, and N-2. -(Aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, aminophenyl Examples thereof include trimethoxysilane, aminophenyl trimethoxysilane, and aminophenyl aminomethylphenyl trimethoxysilane. When particularly high heat resistance is required in the process, it is desirable to connect Si and an amino group with an aromatic group.
In the present invention, a phosphorus-based coupling agent, a titanate-based coupling agent, or the like may be used in combination, if necessary.

The coating method of the silane coupling agent in the present invention is not particularly limited, and a general wet coating method or a vapor phase coating method can be used. As a wet coating method, a stock solution or solvent solution of a silane coupling agent, preferably an alcohol solution, is used, and spin coating, capillary coating, bar coating, applicator, die coating, comma coating, screen printing, gravure printing, inkjet printing, etc. , Spray coating, spray coating and the like can be used.
In the present invention, as the silane coupling agent coating method, preferably, a gas phase coating method via a gas phase can be used. The vapor phase coating method is performed by exposing an inorganic substrate to a vaporized silane coupling agent. The application of the silane coupling agent may be paraphrased as the treatment of the silane coupling agent. Vaporization refers to the state in which the vapor of the silane coupling agent, that is, the silane coupling agent in a substantially gaseous state or the silane coupling agent in a fine particle state is present. The exposure means that the organic polymer film is in contact with the gas or vacuum state containing the vaporized silane coupling agent.

The vapor of the silane coupling agent can be easily obtained by heating the liquid silane coupling agent to a temperature from 40 ° C. to the boiling point of the silane coupling agent. The above of the silane coupling agent is produced even if it is below the boiling point. A state in which fine particles of the silane coupling agent coexist can also be used. Further, an operation of increasing the steam density may be performed by manipulating the temperature and pressure. The boiling point of the silane coupling agent varies depending on the chemical structure, but is generally in the range of 100 to 250 ° C. However, heating at 200 ° C. or higher is not preferable because it may cause a side reaction on the organic group side of the silane coupling agent.

The environment for heating the silane coupling agent may be under pressure, normal pressure, or reduced pressure, but in the case of promoting vaporization of the silane coupling agent, it is generally preferable under normal pressure or reduced pressure. Since the silane coupling agent is often classified as a flammable liquid, it is preferable to carry out the vaporization work in a closed container, preferably after replacing the inside of the container with an inert gas.
On the other hand, from the viewpoint of improving production efficiency and reducing the price of production equipment, it is desirable to apply a silane coupling agent in an environment that does not use vacuum. For example, an organic polymer film is set in a chamber under normal pressure, the inside of the chamber is filled with a carrier gas at substantially normal pressure containing a silane coupling agent vaporized, and the silane coupling agent is deposited, and then vaporized again. It can be carried out at approximately atmospheric pressure until it is returned to the state without the silane coupling agent.

In the present invention, it is preferable that the device is formed on the side of the second polyimide layer opposite to the first polyimide layer.
Here, the device in the present invention refers to an electronic circuit including a wiring board responsible for electrical wiring, an active element such as a transistor and a diode, and a passive device such as a resistor, a capacitor, an electric double layer capacitor and an inductor, and other pressures and temperatures. Sensor elements that sense light, humidity, etc., light emitting elements, liquid crystal displays, electrophoresis displays, self-luminous displays and other image display elements, wireless and wired communication elements, arithmetic elements, storage elements, MEMS elements, solar cells, primary batteries , Secondary battery, thin film, quantum dot, quantum wire, quantum wire transistor, single-electron transistor, single-electron memory, etc.
The device in the present invention preferably includes an electrical wiring layer. Further, the device in the present invention preferably includes a semiconductor element. Further, the device of the present invention preferably includes a gas barrier layer such as a water vapor barrier, an oxygen barrier, and a hydrogen sulfide barrier.

In the laminate of the present invention, at least a step of applying a solution of a polyimide resin to be a first polyimide layer or a precursor solution to an inorganic substrate and forming a first polyimide layer by a process involving heating, followed by a step of forming the first polyimide layer. It can be obtained by laminating a polyimide film to be the second polyimide layer on the surface of the first polyimide layer opposite to the inorganic substrate.

Further, in the present invention, the device is formed on the surface of the second polyimide layer opposite to the first polyimide layer, and then the first polyimide layer and the second polyimide layer are separated from each other to form a device. A device formed on the polyimide layer of 2 can be obtained. Here, the second polyimide layer functions as a flexible substrate, and the obtained device becomes a flexible device.

In the present invention, it is preferable to operate the first polyimide layer so that the area covering the inorganic substrate is larger than the area of the second polyimide layer. This is a preferable and necessary requirement for setting the first polyimide layer to dominate in the overall physical characteristics of the laminate.
On the other hand, in the present invention, the area covered by the first polyimide layer covering the inorganic substrate is larger than the area of the second polyimide layer, and the second polyimide layer has an area in direct contact with the inorganic plate. preferable. Since the region where the second polyimide layer is in direct contact with the inorganic substrate has high adhesiveness to the second polyimide layer, an effect of preventing peeling trouble of the second polyimide layer during the process can be expected. Further, when the second polyimide layer is peeled off, the second polyimide layer can be peeled off without damaging the first polyimide layer by using the portion in direct contact with the inorganic substrate as a trigger. It becomes.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The method for evaluating the physical properties in the following examples is as follows.

<Reducing viscosity of polyamic acid (ηsp / C)>
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so as to have a polymer concentration of 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube. (When the solvent used to prepare the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved using N, N-dimethylacetamide and measured.)

<Film thickness of polyimide layer>
The first polyimide layer was determined by observing the SEM cross section of the cross section of the laminate. Unless otherwise specified, the average value of the film thicknesses of five randomly selected points in the region 1 mm or more inside from the end of each polyimide layer was defined as the film thickness of the polyimide layer.
In the second polyimide layer, an arithmetic mean value of 10 randomly selected points of the polyimide film before lamination or the film after peeling the second polyimide layer by 90 degrees from the laminate was obtained and used as the film thickness. Further, the film thickness unevenness [%] was calculated from the maximum value, the minimum value, and the arithmetic mean value of the film thickness at any 10 points by the following formula.
Film thickness spot = 100 x (maximum value-minimum value) / arithmetic mean value [%]
The thickness of the polyimide film, which is the second polyimide layer, is measured with a stylus type film thickness meter.
Further, when the peeling was successful, the film thickness and the film thickness unevenness of the polyimide film and the film thickness unevenness after the peeling were almost the same as those of the polyimide film before laminating.

<Pyrolysis temperature>
Using the polyimide layer (polyimide film) peeled off from the laminated plate as a sample, dry it at 150 ° C. for 30 minutes, and then perform thermogravimetric measurement (TGA) under the following conditions. The temperature at which the mass of the sample decreases by 5% is defined as the thermal decomposition temperature. did.
Device name: TG-DTA2000S manufactured by MAC Science
Bread: Aluminum pan (non-airtight type)
Sample mass: 10 mg
Temperature rise start temperature: 30 ° C
Heating rate: 20 ° C / min
Atmosphere: Argon

<90 degree peel strength>
Measurement was performed according to the 90-degree peeling method specified in JIS K6854-1: 1999.
Device name: Shimadzu Autograph AG-IS
Measurement temperature: Room temperature Peeling speed: 100 mm / min
Atmosphere: Atmosphere measurement sample width: 10 mm

<Undercut>
The undercut was determined by the method shown in FIG. First, a cross-sectional observation of the vicinity of the edge of the first polyimide layer is performed. The vicinity of the edge means a region from the edge edge to the inside of the polyimide layer by about 3 mm. First, the average film thickness of the polyimide layer is randomly measured at 5 points in a region 1 mm or more inside from the edge edge, and the arithmetic mean is obtained, which is defined as the film thickness T. Next, the distance from the portion where the film thickness at the edge edge of the polyimide layer is 0.1 T to the location where the film thickness is 0.9 T: undercut U is obtained. For U, the arithmetic mean of U obtained from the cross-sectional views of five randomly selected edges of each sample is used.
<Coefficient of linear expansion>
In the film obtained by peeling the polyimide layer, the expansion / contraction rate was measured under the following conditions, and the expansion / contraction rate / temperature was measured at intervals of 30 ° C. to 45 ° C., 45 ° C. to 60 ° C., ... And 15 ° C. This measurement was carried out up to 300 ° C., and the average value of all the measured values was calculated as CTE.
Device name: TMA4000S manufactured by MAC Science
Sample length: 20 mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rise end temperature: 400 ° C
Heating rate: 5 ° C / min
Atmosphere: Argon

<Manufacturing example>
[Manufacture of polyimide precursor (polyamic acid) solution PV1]
After replacing the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer and a stirring rod with nitrogen, 223 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole and 4416 parts by mass of N, N-dimethylacetamide were added. After completely dissolving the solution, the mixture was stirred at 217 parts by mass of pyromellitic dianhydride at a reaction temperature of 25 ° C. for 24 hours to obtain a brown and viscous polyamic acid solution [PV1].

[Manufacture of polyimide precursor (polyamic acid) solution PV2]
After replacing the inside of the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod with nitrogen, 3,3', 4,4'-biphenyltetracarboxylic dianhydride as tetracarboxylic dianhydride, 398 parts by mass of para When 132 parts by mass of phenylenediamine and 30 parts by mass of 4,4'diaminodiphenyl ether were dissolved in 4600 parts by mass of N, N-dimethylacetamide and stirred at a reaction temperature of 25 ° C. for 24 hours, a brown and viscous polyamic acid solution [ PV2] was obtained.

[Manufacture of polyimide precursor (polyamic acid) solution PV3]
After nitrogen substitution in the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, 545 parts by mass of pyromellitic acid anhydride and 500 parts by mass of 4,4'diaminodiphenyl ether were added to 8000 parts by mass of N, N-dimethylacetamide. And the same reaction was carried out while keeping the temperature at 20 ° C. or lower to obtain a polyamic acid solution [PV3].
[Manufacture of polyimide precursor (polyamic acid) solution PV4]
After nitrogen substitution in the reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, 545 parts by mass of pyromellitic dianhydride, 153 parts by mass of paraphenylenediamine, and 200 parts by mass of 4,4'diaminodiphenyl ether were added by 8000 parts by mass. It was dissolved in N, N-dimethylacetamide of the part and reacted in the same manner while keeping the temperature at 20 ° C. or lower to obtain a polyamic acid solution [PV4].

[Manufacture of polyimide precursor (polyamic acid) solution PV5]
After replacing the inside of the reaction vessel equipped with a nitrogen introduction tube, thermometer, and stirring rod with nitrogen, the reaction vessel was placed in a nitrogen atmosphere with 2,2'-dimethyl-4,4'-diaminobiphenyl 155.9 parts by mass and N, After 1200 parts by mass of N-dimethylacetamide was charged and dissolved, 142.9 parts by mass of cyclobutanetetracarboxylic acid dianhydride was added separately as a solid while cooling the reaction vessel, and the mixture was stirred at room temperature for 5 hours. Then, it was diluted with 1000 parts by mass of N, N-dimethylacetamide to obtain a polyamic acid solution [PV5] having a reducing viscosity of 4.20 dl / g.

[Manufacture of polyimide precursor (polyamic acid) solution PV6]
After replacing the inside of the reaction vessel equipped with a nitrogen introduction tube, thermometer, and stirring rod with nitrogen, the reaction vessel was charged with 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl 176.5 parts by mass under a nitrogen atmosphere. After charging and dissolving 1200 parts by mass of N, N-dimethylacetamide, 122.9 parts by mass of 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride was added separately as a solid while cooling the reaction vessel. , Stirred at room temperature for 18 hours. Then, it was diluted with 500 parts by mass of N, N-dimethylacetamide to obtain a polyamic acid solution [PV6] having a reducing viscosity of 3.26 dl / g.

<Inorganic substrate (support)>
As the glass substrate [G1], OA10G manufactured by Nippon Electric Glass with a size of 235 mm × 185 mm and a thickness of 0.7 mm was used.
As the glass substrate [G2], a blue plate glass having a size of 235 mm × 185 mm and a thickness of 0.7 mm was used.
As the silicon wafer [SW], a single-sided mirror-finished wafer having a diameter of 200 mm and a thickness of 0.7 mm was used.

<Characteristics of polyimide resin of the first polyimide layer>
The obtained polyamic acid solution [PV1] is applied to the glass substrate 1, the coating film thickness is appropriately adjusted so that the final film thickness is 20 to 25 μm, and polyimideization is performed by drying and heat treatment at a predetermined temperature. Table 1 shows the results of evaluating the polyimide resin peeled from the glass substrate. "Varnish film formation" in the table indicates that the polyimide obtained by this method was used.

<Manufacturing of polyimide film to be the second polyimide layer>
After defoaming the polyamic acid solution [PV1] obtained in the production example, it was applied to the smooth surface of the polyester film A4100 manufactured by Toyobo Co., Ltd. using a comma coater, and the drying temperature was set to 95 ° C. in a continuous dryer. It was dried for 5 minutes at 115 ° C. for 5 minutes to obtain a polyamic acid film. Next, the obtained polyamic acid film was peeled off from the polyester film, both ends of the film were gripped with pins, and heat treatment was performed at 250 ° C. for 3 minutes and 490 ° C. for 3 minutes in a continuous heat treatment furnace until the temperature reached room temperature. The mixture was cooled to obtain a polyimide film [PF1a]. The evaluation results of the obtained polyimide film are shown in Table 1. "Film film formation" in the table indicates that the polyimide film obtained by this method was used.
Similarly, the polyamic acid solution, the film forming method, the coating film thickness, the drying, and the heat treatment conditions were changed to form a solution, and the polyimide film shown in Table 1 was obtained. The results are shown in Table 1.

The abbreviations in Tables 1 to 3 are as follows.
PMDA: pyromellitic dianhydride,
BPDA: 3,3', 4,4'-biphenyltetracarboxylic dianhydride,
CBA: Cyclobutane tetracarboxylic dianhydride,
CHA: 1,2,4,5-cyclohexanetetracarboxylic dianhydride,
ODA: 4,4'diaminodiphenyl ether,
PDA: Phenylenediamine,
DAMBO: 5-amino-2- (p-aminophenyl) benzoxazole,
BPA: 2,2'-dimethyl-4,4'-diaminobiphenyl,
FA: 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl,
CTE: Coefficient of linear expansion,
UV / O3: UV ozone treatment

<Example 1>
After replacing the chamber with the hot plate and the support base of the inorganic substrate with clean dry nitrogen, the inorganic substrate is installed on the support base, and the silane coupling agent (silane coupling agent) so that the liquid level is located 200 mm below the inorganic substrate. A chalet filled with 3-aminopropyltrimethoxysilane) is placed, the chalet is heated to 100 ° C. on a hot plate, the lower surface of the inorganic substrate is exposed to the silane coupling agent vapor for 3 minutes, then removed from the chamber and placed in a clean bench. On a hot plate whose temperature was adjusted to 120 ° C., the side opposite to the exposed surface of the inorganic substrate was placed in contact with the hot plate, and heat treatment was performed for 1 minute.
Next, a polyamic acid solution [PV1] to be the first polyimide layer was applied to the silane coupling agent-treated surface of the inorganic substrate with a bar coater, and dried and heat-treated in a clean oven. The drying conditions and heat treatment conditions are shown in Table 1.
The inorganic plate on which the first polyimide layer is formed is again placed in a chamber provided with a hot plate and a support base for the inorganic substrate, and the first polyimide layer is formed on the support base on the inorganic substrate on which the first polyimide layer is formed. Install it face down, similarly expose it to silane coupling agent vapor, remove it from the chamber, install it in a clean bench, and place the hot plate at 120 ° C. so that the inorganic substrate side is in contact with the hot plate. It was placed on the substrate and heat-treated for 1 minute.

The polyimide film [PF1a] to be the second polyimide layer was subjected to nitrogen plasma treatment with a continuous plasma treatment device, and then cut into a predetermined size. A polyimide film was laminated so as to overlap the first polyimide layer of the previously obtained inorganic substrate treated with a silane coupling agent, temporarily pressure-bonded with a roll laminator, installed in a clean bench, and adjusted to 150 ° C. The inorganic substrate side was placed on a warm hot plate so as to be in contact with the hot plate, and heat treatment was performed for 3 minutes to obtain a laminate.
In the obtained laminate, the adhesive strength between the first polyimide layer and the inorganic substrate [N / cm], the adhesive strength between the second polyimide layer and the first polyimide layer [N / cm], and actually the first polyimide. The situation when the second polyimide layer was peeled from the layer was evaluated as "peeling property". Good peelability indicates that the second polyimide layer could be peeled off as a film without any problem. Further, the laminate prepared under the same conditions was heat-treated in vacuum at 450 ° C. for 30 minutes, cooled to room temperature, left to stand for 24 hours, and then the adhesive strength between the second polyimide layer and the first polyimide layer [N / cm] was measured, and "peeling property" was evaluated in the same manner. The results are shown in Tables 2 to 3.

<Examples 2 to 13, Comparative Examples 1 to 3>
Hereinafter, experiments were carried out by appropriately replacing the inorganic substrate, the first polyimide layer, and the second polyimide layer to obtain the laminates of Examples 2 to 13 and Comparative Examples 1 to 3 shown in Tables 2 and 3. It was. The evaluation results of each laminated body are shown in Tables 2 to 3. In terms of peelability, "split" indicates that the second polyimide layer was cracked during film peeling, and a good quality film could not be obtained. Further, "co-peeling" indicates that the second polyimide layer was not peeled off, and the first polyimide layer was peeled off from the inorganic substrate. Further, "film chipping" indicates that the edge or corner of the peeled second polyimide layer is chipped. This indicates that the deterioration of the film or the tensile breaking strength of the film is not sufficient for the adhesive force.
Arrangement A in the table shows the arrangement of FIG. 3, and arrangement B shows the arrangement of FIG. In the example using the silicon wafer, both the first polyimide layer and the second polyimide layer had the same size as the silicon wafer.
For the surface treatment of the inorganic substrate, a UV / ozone cleaning reformer SKR1102N-03 manufactured by Lan Technical Service Co., Ltd. was used, and irradiation was performed for one minute with a distance of 30 mm between the lamp and the inorganic substrate.

As described above, the laminate of the present invention can be satisfactorily peeled between the first polyimide layer and the second polyimide layer. Therefore, when manufacturing a flexible device using the second polyimide layer as a flexible substrate, the stress on the flexible device in the peeling step can be minimized. Therefore, if the laminate of the present invention is applied to the production of a flexible device using a temporary support substrate, a high-performance flexible device can be produced in a high yield, and it is said that the industrial applicability is extremely high. Eh.

Claims (9)

In a laminated body including an inorganic substrate, a first polyimide layer adjacent to the inorganic substrate, and a second polyimide layer located on the opposite side of the first polyimide layer from the inorganic substrate.
The first polyimide layer is a condensate of pyromellitic dianhydride and 5-amino-2- (p-aminophenyl) benzoxazole.
The film thickness unevenness of the second polyimide layer is 5% or less, and the tensile breaking strength is 90 MPa or more.
Adhesive strength between the inorganic substrate and the first polyimide layer is F1,
The adhesive strength of the first polyimide layer and the second polyimide layer after being heat-treated at 450 ° C. for 30 minutes is F2.
When, F1 ≧ 2 × F2, and
Set the thermal decomposition temperature of the first polyimide layer to Temp 1,
Set the thermal decomposition temperature of the second polyimide layer to Temp2,
When
Temp1 ≧ Temp2
A laminate characterized by being. When the average film thickness of the first polyimide layer is T and the undercut of the edge portion of the first polyimide layer is U.
U> T
The laminate according to claim 1, wherein the laminate is characterized by the above. The laminate according to claim 1 or 2, wherein a silane coupling agent layer is provided between the inorganic substrate and the first polyimide layer. The laminate according to any one of claims 1 to 3, wherein the device is formed on the side of the second polyimide layer opposite to the first polyimide layer. The laminate according to any one of claims 1 to 4, wherein the device includes an electrical wiring layer. The laminate according to any one of claims 1 to 5, wherein the device includes a semiconductor element. The laminate according to any one of claims 1 to 6, wherein the device includes a gas barrier layer. At least, a step of applying a solution of a polyimide resin to be a first polyimide layer or a precursor solution to an inorganic substrate and forming a first polyimide layer by a process involving heating, and then an inorganic of the first polyimide layer. A claim comprising a step of forming a second polyimide layer by laminating a polyimide film having a film thickness unevenness of 5% or less and a tensile breaking strength of 90 MPa or more on a surface opposite to the substrate. Item 8. The method for producing a laminate according to any one of Items 1 to 7. The laminate according to any one of claims 4 to 7 is characterized in that a device formed on the second polyimide layer is obtained by peeling between the first polyimide layer and the second polyimide layer. Flexible device manufacturing method.

Images