JP2012206382A - Substrate for flexible device, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a flexible device improved in yield by suppressing a decline in electrical properties caused by disconnection or the like even if a film thickness is made extremely thin.SOLUTION: The substrate 1 for the flexible device includes a base material 2, and a flattened layer 3 formed on the base material 2 and containing polyimide. The surface roughness Ra of a measurement region 10 μm square on the surface of the flattened layer 3 is 5 nm or less, and the surface roughness Ra of a measurement region 1 μm square on the surface of the flattened layer 3 is 5 nm or less. The number average molecular weight of polyimide is 2,000-1,000,000.

Description

  The present invention relates to a flexible substrate used for a flexible device such as an organic electroluminescence display device and electronic paper.

  Metal substrates and plastic substrates are used as substrates for manufacturing thin film elements such as thin film transistors, thin film solar cells, and electroluminescence elements that are members of flexible devices (Patent Document 1, etc.).

  The elements formed on the substrate have been made thinner than conventional ones in order to obtain flexibility and improve the productivity of the sputtering method, and have come to be formed with nanoscale thickness. ing.

  Due to the above situation, thinning is further advanced than conventional elements, but due to the thinning, elements such as disconnection due to extremely minute irregularities on the surface of the substrate that have not been a problem in the past. There is a problem in that the electrical properties of the material deteriorate. As a result, the device manufacturing yield has been lowered. Therefore, nanoscale surface flatness is required on the surface of the substrate.

  However, for example, the surface of the metal foil has not reached the nano-order flatness due to the influence of rolling marks and the like by a roll. Moreover, even in the case of a single film, it is difficult to provide high flatness because it does not have a support for production and needs to be peeled off from the support. Under the circumstances as described above, it is desired to develop a flexible device substrate having a very high smoothness on the substrate surface and a high yield.

JP 2008-147207 A

  It is an object of the present invention to provide a substrate for a flexible device, in which a decrease in electrical properties due to disconnection or the like is suppressed even when the film thickness is very thin, thereby improving the yield.

  Under the circumstances as described above, as a result of intensive studies, the present inventors have laminated a flattening layer on a substrate such as a metal foil or a resin film, and measured the surface area of the flattening layer at 10 μm square and 1 μm square. Succeeded in producing a flexible device substrate having a surface roughness Ra of 5 nm or less, both having a very high surface smoothness. The present invention relates to a novel flexible device substrate having high surface smoothness.

Accordingly, the present invention provides the following flexible device substrate and method for producing the same:
Item 1. A planarization layer formed on the substrate and containing polyimide, the surface roughness Ra at a measurement area of 10 μm square on the planarization layer surface is 5 nm or less, and the planarization layer A substrate for a flexible device having a surface roughness Ra of 5 nm or less at a surface measurement region of 1 μm square.

  Item 2. The board | substrate for flexible devices of Claim 1 whose number average molecular weights of the said polyimide are 2,000-1,000,000.

  Item 3. The board | substrate for flexible devices of Claim 1 or 2 whose film thickness of the said planarization layer is 0.2-1000 micrometers.

  Item 4. Item 4. The flexible device substrate according to any one of Items 1 to 3, wherein the planarization layer has a hygroscopic expansion coefficient within a range of 0 ppm /% RH to 15 ppm /% RH.

  Item 5. Item 5. The flexible device substrate according to any one of Items 1 to 4, wherein the planarizing layer is partially formed on the substrate.

  Item 6. Item 6. The flexible device substrate according to any one of Items 1 to 5, wherein a linear thermal expansion coefficient of the planarizing layer is in a range of 0 ppm / ° C to 25 ppm / ° C.

  Item 7. Item 7. The flexible device substrate according to any one of Items 1 to 6, wherein a difference between a linear thermal expansion coefficient of the planarizing layer and a linear thermal expansion coefficient of the base material is 15 ppm / ° C. or less.

  Item 8. Item 8. The flexible device substrate according to any one of Items 1 to 7, wherein the thickness of the base material is within a range of 1 μm to 1000 μm.

  Item 9. The manufacturing method of the board | substrate for flexible devices as described in any one of claim | item 1 -8 including the insulating layer formation process which apply | coats a polyimide resin composition on a base material by a die-coat method, and forms an insulating layer.

Moreover, this invention provides the thin-film transistor substrate for flexible devices, a flexible device, an organic electroluminescent display apparatus, and electronic paper which are shown below:
Item 10. Item 9. A flexible device thin film transistor substrate comprising: the flexible device substrate according to any one of items 1 to 8; and a thin film transistor formed on an adhesion layer of the flexible device substrate.

  Item 11. Item 11. The thin film transistor substrate for flexible devices according to Item 10, wherein the thin film transistor has an oxide semiconductor layer.

  Item 12. Item 12. A flexible device comprising the thin film transistor substrate for flexible device according to Item 10 or 11.

Item 13. A substrate for a flexible device having a base material, a planarization layer formed on the base material and containing polyimide, and an adhesion layer formed on the planarization layer and containing an inorganic compound;
A back electrode layer and a thin film transistor formed on the adhesion layer of the flexible device substrate;
An electroluminescence layer formed on the back electrode layer and including at least an organic light emitting layer;
An organic electroluminescence display device comprising: a transparent electrode layer formed on the electroluminescence layer.

Item 14. A substrate for a flexible device having a base material, a planarization layer formed on the base material and containing polyimide, and an adhesion layer formed on the planarization layer and containing an inorganic compound;
A back electrode layer and a thin film transistor formed on the adhesion layer of the flexible device substrate;
A display layer formed on the back electrode layer;
An electronic paper comprising: a transparent electrode layer formed on the display layer.

  If an attempt is made to reduce the thickness of an element for a flexible device, even an extremely minute surface irregularity, which has not been a problem in the past, may cause disconnection or the like. In addition, even if the surface of an organic EL device is made thin, even if the surface is very small, the current density is different as a result of the difference in electrical resistance caused by the unevenness of the thickness of the device layer in the uneven portion. Also, there may be a problem such that excessive heat is generated only in a part of the element. In this way, if an element is made thin, even if it is a minute unevenness, the electrical property is deteriorated. However, since the substrate for flexible devices of the present invention has a very smooth surface roughness Ra of 5 nm in the measurement area of 1 μm square and 10 μm square on the surface of the flattened layer, an element having excellent electrical properties can be obtained. Can be manufactured. In addition, since the above-described problems are greatly suppressed by improving the smoothness of the surface, the product yield can also be improved.

It is a schematic sectional drawing which shows an example of the board | substrate for flexible devices of this invention. It is a schematic sectional drawing which shows an example of the board | substrate for flexible devices of this invention. It is sectional drawing which shows the outline of a typical die-coating method.

  Hereinafter, flexible device substrate, flexible device TFT substrate, flexible device, organic EL display device, electronic paper, thin film element substrate, thin film element, TFT, thin film element substrate manufacturing method, thin film element manufacturing method of the present invention The TFT manufacturing method will be described in detail.

A. First, the flexible device substrate of the present invention will be described.

  The substrate for a flexible device of the present invention has a base material and a planarization layer formed on the base material and containing polyimide, and the surface roughness Ra at a measurement region of 10 μm square on the surface of the planarization layer is 5 nm. The surface roughness Ra in the measurement area of 1 μm square on the surface of the planarizing layer is 5 nm or less.

  The board | substrate for flexible devices of this invention is demonstrated referring drawings. FIG. 1 is a schematic cross-sectional view showing an example of the flexible device substrate of the present invention. A flexible device substrate 1 illustrated in FIG. 1 includes a base material 2 and a planarization layer 3 formed on the base material 2 and containing polyimide.

  The flexible device substrate of the present invention may further have an adhesion layer containing an inorganic compound on the substrate and the planarization layer. FIG. 2 is a schematic sectional view showing another embodiment of the flexible device substrate of the present invention. A flexible device substrate 1 illustrated in FIG. 2 is formed on a base material 2, the base material 2, a planarization layer 3 containing polyimide, and an adhesion layer 4 formed on the planarization layer 3 and containing an inorganic compound. And have.

Hereafter, each structure of the board | substrate for flexible devices of this invention is demonstrated:
1. Base material The base material in this invention shows the film-form support body which supports said planarization layer. Examples of the substrate include metal foil and resin film.

  The linear thermal expansion coefficient of the substrate is preferably in the range of 0 ppm / ° C. to 25 ppm / ° C., more preferably in the range of 0 ppm / ° C. to 18 ppm / ° C., more preferably from the viewpoint of dimensional stability. It is in the range of 0 ppm / ° C. to 12 ppm / ° C., particularly preferably in the range of 0 ppm / ° C. to 7 ppm / ° C. In addition, about the measuring method of the said linear thermal expansion coefficient, it is the same as the measuring method of the linear thermal expansion coefficient of the said planarization layer except cut | disconnecting a base material to width 5mm x length 20mm and making it an evaluation sample.

  Moreover, it is preferable that a base material has oxidation resistance. This is because when a TFT is produced on the flexible device substrate of the present invention, a high-temperature treatment is usually performed during the production of the TFT. In particular, when the TFT includes an oxide semiconductor layer, the base material preferably has oxidation resistance because annealing is performed at a high temperature in the presence of oxygen.

  The thickness of the substrate is not particularly limited as long as it can satisfy the above-mentioned characteristics, but specifically, it is preferably in the range of 1 μm to 1000 μm, more preferably in the range of 1 μm to 200 μm. More preferably, it is in the range of 1 μm to 100 μm. If the thickness of the substrate is too thin, the gas barrier properties against oxygen and water vapor may be reduced, and the strength of the flexible device substrate may be reduced. Moreover, when the thickness of a base material is too thick, flexibility will fall, it will become heavy, and cost will become high.

  The surface roughness Ra of the substrate is larger than the surface roughness Ra of the flattening layer, and is about 50 nm to 200 nm, for example, when a metal foil is used. In addition, about the measuring method of the said surface roughness, it is the same as that of the measuring method of the surface roughness of the smooth layer mentioned later.

  When a metal foil is used as the base material, the metal material constituting it is not particularly limited as long as it can be a foil and satisfies the above-mentioned characteristics. For example, aluminum, copper, copper Examples include alloys, phosphor bronze, stainless steel (SUS), gold, gold alloys, nickel, nickel alloys, silver, silver alloys, tin, tin alloys, titanium, iron, iron alloys, zinc, and molybdenum. Among these, SUS is preferable when applied to a large element. SUS is excellent in oxidation resistance and heat resistance, and has a smaller coefficient of linear thermal expansion than copper and has excellent dimensional stability. Further, SUS304 has an advantage that it is particularly easy to obtain, and SUS430 has an advantage that it is easy to obtain and the linear thermal expansion coefficient is smaller than SUS304. On the other hand, when a TFT substrate is produced using the flexible device substrate of the present invention, considering the linear thermal expansion coefficient of the metal foil and TFT, from the viewpoint of the linear thermal expansion coefficient, the linear thermal expansion coefficient is lower than that of SUS430. Titanium and invar are preferred. However, it is desirable to select not only the linear thermal expansion coefficient but also considering the workability of the foil and the cost due to the oxidation resistance, heat resistance, malleability and ductility of the metal foil.

  The metal foil may be a rolled foil or an electrolytic foil, and is appropriately selected according to the type of metal material. Usually, the metal foil is produced by rolling.

  When using a resin film as a base material, a polyimide resin, a polyethylene naphthalate containing resin, a polyethylene terephthalate containing resin, an epoxy containing resin, etc. are mentioned. The polyimide-containing resin described later can be used as a raw material for the planarizing layer.

  When the resin film is used as the substrate, the surface roughness Ra is larger than the surface roughness Ra of the planarizing layer, and is, for example, about 5 nm to 100 nm. In addition, about the measuring method of the said surface roughness, it is the same as that of the measuring method of the surface roughness of the smooth layer mentioned later.

  After forming the planarization layer containing a polyimide on a base material, it can also be set as the board | substrate for flexible devices in which the base material was partially formed by patterning a base material. That is, the base material may be formed on the entire surface of the planarizing layer, or may be partially formed on the planarizing layer. Furthermore, in other words, the base material may be formed on the entire surface of the flexible device substrate, or may be partially formed on the flexible device substrate. When the base material is formed on the entire surface of the flexible device substrate, gas barrier properties against oxygen and water vapor can be imparted, and heat dissipation can be enhanced. On the other hand, when the substrate is partially formed, weight reduction can be achieved by removing unnecessary substrate portions.

  As a substrate patterning method, a photolithography method, a method of directly processing with a laser or the like can be used. As a photolithographic method, for example, after laminating a dry film resist on a base material in the state of a laminate of a base material and a planarizing layer, patterning the dry film resist, and etching the base material along the pattern And a method of removing the dry film resist.

  When a metal substrate is used as the substrate, the metal substrate may be subjected to chemical treatment.

  In the embodiment, the method for the chemical treatment of the metal substrate is not particularly limited as long as the wettability of the polyimide resin composition with respect to the metal substrate can be improved. , Electric field degreasing, pickling and the like.

  Alkaline cleaning is a method in which the surface of a metal substrate is eluted and washed, for example, by dipping in an alkaline chemical solution or by applying a paste-like alkaline cleaning agent. Gloss does not come out, but can be used for cheap and large products. Since the glossy portion will become frosted, alkali cleaning can be applied if the appearance is not a problem, such as to remove darkening due to welding burn.

  Electrolytic degreasing is a method of making a smooth and glossy surface by eluting convex portions (micron level) on the surface of a metal substrate by conducting electricity (electrolysis) in a chemical solution. Since the dirt and impurities attached to the surface of the metal substrate are removed and the film is strengthened, the corrosion resistance can be improved. This is presumably because iron on the surface of the metal base material is first dissolved by electrolysis, so that metal components (for example, chromium) other than iron are relatively thick and the passive film becomes strong.

  Pickling is a method in which the surface of a metal substrate is eluted and washed by soaking it in a strongly acidic chemical solution or by applying a paste-like acid detergent. Gloss does not come out, but can be used for cheap and large products. Pickling can be applied if the appearance is not a problem, for example, to remove darkening due to welding burns, because the glossy part will be frosted.

  In the said embodiment of this invention, it is preferable to perform a chemical | medical solution process so that the contact angle with respect to the solvent contained in the polyimide resin composition of the metal base material surface may fall. Specifically, it is preferable to perform a chemical treatment so that the contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate is 30 ° or less. The contact angle with respect to the solvent contained in the polyimide resin composition on the surface of the metal substrate after the chemical treatment is preferably 30 ° or less, more preferably 20 ° or less, and further preferably 10 ° or less.

  The ratio of the amount of carbon (C) to the total amount of elements detected by X-ray photoelectron spectroscopy (XPS) on the surface of the metal substrate after the chemical treatment is preferably 0.25 or less. More preferably, it is 20 or less.

2. Planarization layer The planarization layer in this invention is formed on a base material, contains a polyimide, and is a layer provided in order to planarize the unevenness | corrugation of a base material surface.

  In the present invention, the surface roughness Ra in the measurement area of 10 μm square on the planarization layer surface is 5 nm or less, and the surface roughness Ra in the measurement area of 1 μm square on the planarization layer surface is also 5 nm or less. Features.

The surface roughness Ra is a value measured using an atomic force microscope (AFM) or a scanning white interferometer. For example, when measuring using AFM, using Nanoscope V multimode (Veeco), in tapping mode, cantilever: MPP11100, scanning range: 1 μm × 1 μm, 10 μm × 10 μm, 100 μm × 100 μm, scanning speed: 0 Ra can be obtained by imaging the surface shape at .5 Hz and calculating the average deviation from the center line of the roughness curve calculated from the obtained image.
When the measurement area is 100 μm × 100 μm, the measurement can be performed using a scanning white interferometer. In this case, using a New View 5000 (manufactured by Zygo), a surface shape in the range of 100 μm × 100 μm was obtained with an objective lens: 100 ×, a zoom lens: 1 ×, and a Scan Length: 15 μm. Ra can be obtained by calculating the average deviation from the center line of the roughness curve calculated from the image.

  From the viewpoint of the yield of the obtained flexible device, in the present invention, the surface roughness Ra in the measurement region of 10 μm square on the planarized layer surface is 5 nm or less, preferably 2 nm or less, more preferably 1 nm or less. In the present invention, the surface roughness Ra in the measurement area of 1 μm square on the surface of the planarizing layer is 5 nm or less, preferably 2 nm or less, more preferably 1 nm or less. Further, the surface roughness Ra in the measurement region of 100 μm square on the planarization layer surface is not particularly limited as long as the surface roughness Ra in the measurement region of 10 μm square and 1 μm square is within the above range, but preferably 30 nm or less, More preferably, it is 20 nm or less.

  The thickness of the planarization layer is preferably 0.2 μm or more, and more preferably 0.5 μm or more. This is because if the film thickness is too thin, it is difficult to flatten the irregularities on the surface of the substrate when formed by coating.

  In the case of forming on a metal foil, the planarization layer needs to have insulating properties, and thus the thickness of the planarization layer is preferably 1 μm or more. This is not the case when a substrate having an insulating property such as a resin film is used in advance.

  In the present invention, the thickness of the planarizing layer is preferably 1000 μm or less, more preferably 200 μm or less, further preferably 100 μm or less, and more preferably 50 μm or less. Also, if the thickness of the flattening layer is too thick, flexibility will be reduced, it will become heavy, drying during film formation will be difficult, and the amount of materials used will increase and the cost will increase. is there.

  Furthermore, when a metal foil is used as a base material and a heat dissipation function is imparted to the flexible device substrate of the present invention, if the flattening layer is thick, polyimide has a lower thermal conductivity than metal, so that heat conduction. Therefore, the thickness is preferably 50 μm or less, and more preferably 20 μm or less.

  The planarization layer contains polyimide, and preferably contains polyimide as a main component. In general, polyimide has water absorption. Since many semiconductor materials used in TFTs and organic EL display devices are sensitive to moisture, the planarization layer has a water-absorbing property in order to reduce moisture inside the device and achieve high reliability in the presence of moisture. Is preferably relatively small. One index of water absorption is the hygroscopic expansion coefficient. Therefore, the smaller the hygroscopic expansion coefficient of the planarizing layer, the better. Specifically, it is preferably within the range of 0 ppm /% RH to 15 ppm /% RH, more preferably 0 ppm /% RH to 12 ppm /% RH. More preferably, it is in the range of 0 ppm /% RH to 10 ppm /% RH. The smaller the hygroscopic expansion coefficient, the smaller the water absorption. For example, when the substrate for a flexible device of the present invention is used for an organic EL display device, the organic EL display device is weak against moisture. Therefore, in order to reduce moisture inside the element, it is preferable that the hygroscopic expansion coefficient is relatively small. Further, if the hygroscopic expansion coefficient of the planarizing layer is in the above range, the water absorption of the planarizing layer can be sufficiently reduced, and the flexible device substrate can be easily stored. When a substrate or an organic EL display device is manufactured, the process becomes simple. Furthermore, the smaller the hygroscopic expansion coefficient, the better the dimensional stability. If the hygroscopic expansion coefficient of the flattening layer is large, the substrate for flexible devices warps as the humidity increases due to the difference in expansion coefficient from the base material where the hygroscopic expansion coefficient is almost zero. May decrease. Therefore, it is preferable that the hygroscopic expansion coefficient is small even when a wet process is performed in the manufacturing process.

The hygroscopic expansion coefficient is measured as follows. First, a film having only a planarizing layer is produced. The method of creating the flattening layer film is a method for producing a flattening layer film on a heat-resistant film (Upilex S 50S (manufactured by Ube Industries)) or a glass substrate, and then peeling the flattening layer film or on the substrate. There is a method in which after the flattening layer film is prepared, the substrate is removed by etching to obtain the flattening layer film. Next, the obtained flattened layer film is cut into a width of 5 mm and a length of 20 mm to obtain an evaluation sample. The hygroscopic expansion coefficient is measured by a humidity variable mechanical analyzer (Thermo Plus TMA8310 (manufactured by Rigaku Corporation)). For example, the temperature is kept constant at 25 ° C., the humidity is first set to a stable state in an environment of 15% RH, the state is maintained for about 30 minutes to 2 hours, and the humidity of the measurement site is set to 20%. RH and hold for 30 minutes to 2 hours until the sample is stable. Thereafter, the humidity is changed to 50% RH, and the difference between the sample length when the humidity becomes stable and the sample length when the humidity becomes stable at 20% RH is expressed as a change in humidity (in this case, 50-20). 30) and the value divided by the sample length is the hygroscopic expansion coefficient (CHE). At the time of measurement, the tensile weight is set to 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample becomes the same.

  In addition, the linear thermal expansion coefficient of the planarizing layer is preferably 15 ppm / ° C. or less, more preferably 10 ppm / ° C. or less, more preferably from the viewpoint of dimensional stability. Is 5 ppm / ° C. or less. The closer the linear thermal expansion coefficient between the flattening layer and the base material, the more the warp of the flexible device substrate is suppressed, and the interface between the flattening layer and the base material when the thermal environment of the flexible device substrate changes. This reduces stress and improves adhesion. In addition, it is preferable that the flexible device substrate of the present invention does not warp in the temperature environment in the range of 0 ° C. to 100 ° C. for handling, but the flattening layer is flattened because the linear thermal expansion coefficient is large. When the linear thermal expansion coefficients of the layer and the substrate are greatly different, the flexible device substrate is warped due to a change in the thermal environment.

  Note that the flexible device substrate is not warped means that the flexible device substrate is cut into a strip shape having a width of 10 mm and a length of 50 mm, and one short side of the obtained sample is placed on a horizontal and smooth table. When fixed, it means that the flying distance from the surface of the other short side of the sample is 1.0 mm or less.

  Specifically, the linear thermal expansion coefficient of the planarization layer is preferably in the range of 0 ppm / ° C. to 30 ppm / ° C., more preferably in the range of 0 ppm / ° C. to 25 ppm / ° C. from the viewpoint of dimensional stability. More preferably, it is in the range of 0 ppm / ° C. to 18 ppm / ° C., particularly preferably in the range of 0 ppm / ° C. to 12 ppm / ° C., and most preferably in the range of 0 ppm / ° C. to 7 ppm / ° C.

The linear thermal expansion coefficient is measured as follows. First, a film having only a planarizing layer is produced. The method for producing the planarizing layer film is as described above. Next, the obtained flattened layer is cut into a width of 5 mm and a length of 20 mm to obtain an evaluation sample. The linear thermal expansion coefficient is measured by a thermomechanical analyzer (for example, Thermo Plus TMA8310 (manufactured by Rigaku Corporation)). The measurement conditions were a heating rate of 10 ° C./min, a tensile load of 1 g / 25,000 μm ² so that the weight per cross-sectional area of the evaluation sample was the same, and an average linear thermal expansion within the range of 100 ° C. to 200 ° C. The coefficient is the linear thermal expansion coefficient (CTE).

The planarizing layer has an insulating property. Specifically, the volume resistance of the planarization layer is preferably 1.0 × 10 ⁹ Ω · m or more, more preferably 1.0 × 10 ¹⁰ Ω · m or more, and 1.0 × 10 9. More preferably, it is ¹¹ Ω · m or more.

  The volume resistance can be measured by a method based on standards such as JIS K6911, JIS C2318, and ASTM D257.

  The polyimide constituting the planarizing layer is not particularly limited as long as it satisfies the above characteristics. For example, it is possible to control the hygroscopic expansion coefficient and the linear thermal expansion coefficient by appropriately selecting the structure of polyimide.

  From the viewpoint of making the linear thermal expansion coefficient and hygroscopic expansion coefficient of the planarization layer suitable for the substrate for flexible devices of the present invention, the polyimide is preferably a polyimide containing an aromatic skeleton. Among polyimides, the polyimide containing an aromatic skeleton is derived from the rigid and highly planar skeleton, and is excellent in heat resistance, insulation in a thin film, and has a low coefficient of linear thermal expansion. It is preferably used for the planarization layer of the substrate for use.

  Since polyimide is required to have low hygroscopic expansion and low linear thermal expansion, it preferably has a repeating unit represented by the following formula (I). Such a polyimide exhibits high heat resistance and insulation properties derived from its rigid skeleton, and exhibits linear thermal expansion equivalent to that of a substrate such as a metal. Furthermore, the hygroscopic expansion coefficient can be reduced.

(In formula (I), R ¹ is a tetravalent organic group, R ² is a divalent organic group, and R ¹ and R ² that are repeated may be the same or different. n is a natural number of 1 or more.)
In the formula (I), generally, R ¹ is a structure derived from tetracarboxylic dianhydride, and R ² is a structure derived from diamine.

  Examples of tetracarboxylic dianhydrides applicable to polyimide include ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclobutane tetracarboxylic dianhydride, methylcyclobutane tetracarboxylic dianhydride, cyclohexane Aliphatic tetracarboxylic dianhydrides such as pentanetetracarboxylic dianhydride; pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3 3′-benzophenone tetracarboxylic dianhydride, 2,3 ′, 3,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,3', 3,4'-biphenyltetracarboxylic dianhydride, 2,2 , 6,6'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride , Bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride Bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1, 1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, , 3-bis [( , 4-Dicarboxy) benzoyl] benzene dianhydride, 1,4-bis [(3,4-dicarboxy) benzoyl] benzene dianhydride, 2,2-bis {4- [4- (1,2- Dicarboxy) phenoxy] phenyl} propane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} propane dianhydride, bis {4- [4- (1, 2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, 4,4′-bis [4- (1, 2-dicarboxy) phenoxy] biphenyl dianhydride, 4,4′-bis [3- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-dicarboxy) ) Phenoxy] phenyl} ke Ton dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfone Anhydride, bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride Bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, 2,2-bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} -1 , 1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} -1,1,1,3 3,3-hexafluoropropane 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3- or 3,4-dicarboxyl Phenyl) propane dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic Acid dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid Dianhydride, pyridinetetracarboxylic dianhydride, sulfonyldiphthalic anhydride, m-terphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, p-terphenyl-3,3' , 4,4'-Tetracarboxylic Dianhydride, 9,9-bis- (trifluoromethyl) xanthenetetracarboxylic dianhydride, 9-phenyl-9- (trifluoromethyl) xanthenetetracarboxylic dianhydride, 12,14-diphenyl-12, 14-bis (trifluoromethyl) -12H, 14H-5,7-dioxapentacene-2,3,9,10-tetracarboxylic dianhydride, 1,4-bis (3,4-dicarboxytrifluoro) Phenoxy) tetrafluorobenzene dianhydride, 1,4-bis (trifluoromethyl) -2,3,5,6-benzenetetracarboxylic dianhydride, 1- (trifluoromethyl) -2,3,5, 6-benzenetetracarboxylic dianhydride, p-phenylenebistrimellitic acid monoester dianhydride, p-biphenylenebistrimellitic acid monoester dianhydride Which aromatic tetracarboxylic dianhydride, and the like.

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

  The tetracarboxylic dianhydride preferably used from the viewpoint of the heat resistance of polyimide, the coefficient of linear thermal expansion, etc. is an aromatic tetracarboxylic dianhydride. Particularly preferably used tetracarboxylic dianhydrides include pyromellitic dianhydride, merophanic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4. , 4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride, 2, 2 ′, 6,6′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1, Examples include 1,3,3,3-hexafluoropropane dianhydride and bis (3,4-dicarboxyphenyl) ether dianhydride.

  Among these, from the viewpoint of reducing the hygroscopic expansion coefficient, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3 2,2 ′, 3′-biphenyltetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) ether dianhydride are particularly preferred.

  When tetracarboxylic dianhydride into which fluorine is introduced is used as the tetracarboxylic dianhydride to be used in combination, the hygroscopic expansion coefficient of polyimide is lowered. However, a polyimide precursor having a skeleton containing fluorine is difficult to dissolve in a basic aqueous solution and needs to be developed with a mixed solution of an organic solvent such as alcohol and a basic aqueous solution.

  In addition, pyromellitic dianhydride, merophanic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride When rigid tetracarboxylic dianhydrides such as 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride and 1,4,5,8-naphthalene tetracarboxylic dianhydride are used, This is preferable because the linear thermal expansion coefficient is small. Among these, from the viewpoint of the balance between the linear thermal expansion coefficient and the hygroscopic expansion coefficient, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic acid The anhydride, 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride is particularly preferred.

  When it has an alicyclic skeleton as tetracarboxylic dianhydride, since the transparency of a polyimide precursor improves, it becomes a highly sensitive photosensitive polyimide precursor. On the other hand, the heat resistance and insulation of polyimide tend to be inferior compared to aromatic polyimide.

When an aromatic tetracarboxylic dianhydride is used, there is a merit that it becomes a polyimide having excellent heat resistance and a low linear thermal expansion coefficient. Therefore, in polyimide, it is preferable that 33 mol% or more of R ¹ in the above formula (I) has any structure represented by the following formula.

  When polyimide contains any structure of the above formula, it is derived from these rigid skeletons and exhibits low linear thermal expansion and low hygroscopic expansion. Furthermore, there is also an advantage that it is easily available on the market and is low cost.

The polyimide having the structure as described above is a polyimide that exhibits high heat resistance and a low linear thermal expansion coefficient. Therefore, the content of the structure represented by the above formula is preferably closer to 100 mol% of R ^{1 in} the above formula (I), but at least 33% or more of R ^{1 in} the above formula (I) is contained. do it. Among them, the content of the structure represented by the above formula is preferably 50 mol% or more, and more preferably 70 mol% or more of R ¹ in the formula (I).

  On the other hand, a diamine component applicable to polyimide can also be used alone or in combination of two or more diamines. The diamine component used is not particularly limited, and examples thereof include p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4 ′. -Diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4, , 4′-diaminodiphenylsulfone, 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3, 4'-di Minodiphenylmethane, 2,2-di (3-aminophenyl) propane, 2,2-di (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2, 2-di (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-di (4-aminophenyl) -1,1,1,3,3,3- Hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (3-aminophenyl)- 1-phenylethane, 1,1-di (4-aminophenyl) -1-phenylethane, 1- (3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane, 1,3-bis (3-Aminophenoxy) benze 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminobenzoyl) ) Benzene, 1,3-bis (4-aminobenzoyl) benzene, 1,4-bis (3-aminobenzoyl) benzene, 1,4-bis (4-aminobenzoyl) benzene, 1,3-bis (3- Amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (3-amino-α, α-dimethylbenzyl) benzene, 1 , 4-bis (4-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,3-bis (4-amino-) , Α-ditrifluoromethylbenzyl) benzene, 1,4-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) Benzene, 2,6-bis (3-aminophenoxy) benzonitrile, 2,6-bis (3-aminophenoxy) pyridine, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis ( 4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [ -(4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 2,2-bis [4- (3- Aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3 3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis [4- ( 3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene , 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [ 4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (3-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 4,4′-bis [4- (4-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, 4,4′-bis [4- (4- Minophenoxy) phenoxy] diphenylsulfone, 3,3′-diamino-4,4′-diphenoxybenzophenone, 3,3′-diamino-4,4′-dibiphenoxybenzophenone, 3,3′-diamino-4-phenoxy Benzophenone, 3,3′-diamino-4-biphenoxybenzophenone, 6,6′-bis (3-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane, 6, Aromatic amines such as 6′-bis (4-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane; 1,3-bis (3-aminopropyl) tetramethyl Disiloxane, 1,3-bis (4-aminobutyl) tetramethyldisiloxane, α, ω-bis (3-aminopropyl) polydimethylsiloxane α, ω-bis (3-aminobutyl) polydimethylsiloxane, bis (aminomethyl) ether, bis (2-aminoethyl) ether, bis (3-aminopropyl) ether, bis (2-aminomethoxy) ethyl] ether , Bis [2- (2-aminoethoxy) ethyl] ether, bis [2- (3-aminoprotoxy) ethyl] ether, 1,2-bis (aminomethoxy) ethane, 1,2-bis (2-amino) Ethoxy) ethane, 1,2-bis [2- (aminomethoxy) ethoxy] ethane, 1,2-bis [2- (2-aminoethoxy) ethoxy] ethane, ethylene glycol bis (3-aminopropyl) ether, diethylene glycol Bis (3-aminopropyl) ether, triethylene glycol bis (3-aminopropyl) ether, ethyl Diamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, Aliphatic amines such as 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane; 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 1, 2-di (2-aminoethyl) cyclohexane, 1,3-di (2-aminoethyl) cyclohexane, 1,4-di (2-aminoethyl) cyclohexane, bis (4-aminocyclohexyl) methane, 2, 6-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl) bicyclo 2.2.1] and alicyclic diamines such as heptane and the like. Examples of guanamines include acetoguanamine, benzoguanamine, and the like, and some or all of the hydrogen atoms on the aromatic ring of the diamine are fluoro group, methyl group, methoxy group, trifluoromethyl group, or trifluoromethoxy group. Diamines substituted with substituents selected from the group can also be used.

  Furthermore, depending on the purpose, any one or two or more of the ethynyl group, benzocyclobuten-4′-yl group, vinyl group, allyl group, cyano group, isocyanate group, and isopropenyl group serving as a crosslinking point, Even if it introduce | transduces into some or all of the hydrogen atoms on the aromatic ring of diamine as a substituent, it can be used.

  The diamine can be selected depending on the desired physical properties. If a rigid diamine such as p-phenylenediamine is used, the polyimide has a low expansion coefficient. Rigid diamines include p-phenylenediamine, m-phenylenediamine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2, 6 as diamines in which two amino groups are bonded to the same aromatic ring. -Diaminonaphthalene, 2,7-diaminonaphthalene, 1,4-diaminoanthracene and the like can be mentioned.

  In addition, diamines in which two or more aromatic rings are bonded by a single bond, and two or more amino groups are each bonded directly or as part of a substituent on a separate aromatic ring, for example, Some are represented by the following formula (II). Specific examples include benzidine and the like.

(In Formula (II), a is a natural number of 0 or 1 or more, and the amino group is bonded to the meta position or the para position with respect to the bond between the benzene rings.)
Further, in the above formula (II), a diamine having a substituent at a position where the amino group on the benzene ring is not substituted and which is not involved in the bond with another benzene ring can be used. These substituents are monovalent organic groups, but they may be bonded to each other. Specific examples include 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-ditrifluoromethyl-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diamino. Biphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl and the like can be mentioned.

  In addition, when fluorine is introduced as a substituent of the aromatic ring, the hygroscopic expansion coefficient can be reduced. However, polyimide precursors containing fluorine, particularly polyamic acid, are difficult to dissolve in a basic aqueous solution, and in the case of partially forming a planarizing layer on a substrate, alcohol or the like is used during the processing of the planarizing layer. It may be necessary to develop with a mixed solution of the organic solvent.

  On the other hand, when a diamine having a siloxane skeleton such as 1,3-bis (3-aminopropyl) tetramethyldisiloxane is used as the diamine, the adhesion with a base material such as a metal foil is improved, or the elastic modulus of polyimide. And the glass transition temperature can be lowered.

  Here, the selected diamine is preferably an aromatic diamine from the viewpoint of heat resistance. However, depending on the desired physical properties, the diamine may be an aliphatic diamine or siloxane within a range not exceeding 60 mol%, preferably not exceeding 40 mol%. Non-aromatic diamines such as diamines may be used.

Moreover, in polyimide, it is preferable that 33 mol% or more of R ² in the formula (I) has any structure represented by the following formula.

(R ³ is a divalent organic group, an oxygen atom, a sulfur atom, or a sulfone group, and R ⁴ and R ⁵ are a monovalent organic group or a halogen atom.)
When polyimide contains any structure of the above formula, it is derived from these rigid skeletons and exhibits low linear thermal expansion and low hygroscopic expansion. Furthermore, there is also an advantage that it is easily available on the market and is low cost.

When it has the above structure, the heat resistance of a polyimide improves and a linear thermal expansion coefficient becomes small. Therefore, the content of the structure represented by the above formula is preferably closer to 100 mol% of R ^{2 in} the above formula (I), but at least 33% or more of R ^{2 in} the above formula (I). It may be contained. Among them, the content of the structure represented by the above formula is preferably 50 mol% or more, and more preferably 70 mol% or more of R ² in the formula (I).

  Generally, the linear thermal expansion coefficient of a base material such as a metal foil, that is, the linear thermal expansion coefficient of a metal is determined to some extent, so the linear thermal expansion coefficient of the planarizing layer is determined according to the linear thermal expansion coefficient of the base material used. The polyimide structure is preferably selected as appropriate.

  In addition, when producing a TFT substrate using the flexible device substrate of the present invention, the linear thermal expansion coefficient of the base material is determined according to the linear thermal expansion coefficient of the TFT, and the linear thermal expansion coefficient of the base material is determined. Accordingly, it is preferable to determine the linear thermal expansion coefficient of the planarizing layer and appropriately select the polyimide structure.

  Furthermore, when producing an organic EL display device or electronic paper using the flexible device substrate of the present invention, the linear thermal expansion coefficient of the substrate is determined according to the linear thermal expansion coefficient of the organic EL display device or electronic paper. And it is preferable to determine the linear thermal expansion coefficient of the planarization layer according to the linear thermal expansion coefficient of the base material, and to select the polyimide structure as appropriate.

  In the present invention, the planarization layer only needs to contain a polyimide having a repeating unit represented by the above formula (I), and this polyimide and another polyimide are laminated or combined as necessary. Alternatively, it may be used as a planarizing layer.

  Moreover, the polyimide which has a repeating unit represented by the said Formula (I) may be obtained using a photosensitive polyimide or a photosensitive polyimide precursor. The photosensitive polyimide can be obtained using a known method. For example, an ethylenic double bond may be introduced into the carboxyl group of polyamic acid by an ester bond or an ionic bond, and a photoradical initiator may be mixed into the resulting polyimide precursor to form a solvent-developed negative photosensitive polyimide precursor. it can. In addition, for example, a naphthoquinone diazide compound is added to polyamic acid or a partially esterified product thereof to obtain an alkali developing positive photosensitive polyimide precursor, or an nifedipine compound is added to polyamic acid to form an alkali developing negative photosensitive polyimide precursor. For example, a photobase generator can be added to the polyamic acid to obtain an alkali development negative photosensitive polyimide precursor.

  In these photosensitive polyimide precursors, 15% to 35% of a photosensitizing component is added to the weight of the polyimide component. Therefore, even if it heats at 300 to 400 degreeC after pattern formation, the residue derived from a photosensitivity provision component remains in a polyimide. Because these residual materials cause the linear thermal expansion coefficient and hygroscopic expansion coefficient to increase, the reliability of the device is greater when using a photosensitive polyimide precursor than when using a non-photosensitive polyimide precursor. Tend to decrease. However, a photosensitive polyimide precursor obtained by adding a photobase generator to polyamic acid can form a pattern even if the amount of photobase generator added as an additive is 15% or less. Since there are few decomposition | disassembly residues derived from an additive, there is little deterioration of characteristics, such as a linear thermal expansion coefficient and a hygroscopic expansion coefficient, and also there is little outgas, it is the most preferable as a photosensitive polyimide precursor applicable to this invention.

  The polyimide precursor used for polyimide can be developed with a basic aqueous solution. From the viewpoint of ensuring the safety of the working environment and reducing process costs when partially forming the planarization layer on the substrate. preferable. Since the basic aqueous solution can be obtained at a low cost and the waste liquid treatment cost and the facility cost for ensuring work safety are low, production at a lower cost is possible.

  Although the planarization layer should just contain a polyimide, it is preferable to have a polyimide as a main component especially. By using polyimide as a main component, it is possible to obtain a planarization layer having excellent insulation and heat resistance. Further, by using polyimide as a main component, the planarization layer can be thinned, the thermal conductivity of the planarization layer is improved, and a flexible device substrate having excellent thermal conductivity can be obtained.

  Note that that the planarizing layer contains polyimide as a main component means that the planarizing layer contains polyimide to the extent that the above-described characteristics are satisfied. Specifically, the content of the polyimide in the planarization layer is 75% by mass or more, preferably 90% by mass or more, and it is particularly preferable that the planarization layer is made of only polyimide. If the content of the polyimide in the planarizing layer is in the above range, it is possible to exhibit characteristics sufficient to achieve the object of the present invention. Properties such as insulation are improved.

  Here, the number average molecular weight of the polyimide is preferably 2,000 to 1,000,000. When the molecular weight is less than 2,000, the viscosity is lowered, but the film properties are also lowered. Moreover, when the amount of the solvent is increased and the solid content is lowered, the viscosity is lowered, but the film thickness is reduced. Therefore, the number average molecular weight is preferable. The number average molecular weight can be calculated by quantifying the ratio between the terminal part of the polymer chain and the main chain part using a nuclear magnetic resonance spectrum.

  Since a polyimide resin has low solubility in a solvent, a method of imidizing by a heat treatment or the like after applying a polyimide precursor such as polyamic acid having high solubility in a solvent to a substrate is generally used.

  The planarization layer may contain additives such as a leveling agent, a plasticizer, a surfactant, and an antifoaming agent as necessary.

  The planarization layer may be formed on the entire surface of the substrate, or may be partially formed on the substrate. That is, a substrate exposed region where the planarization layer and the adhesion layer are not present and the substrate is exposed may be provided on the surface of the substrate where the planarization layer and the adhesion layer are formed. When having such a base material exposure region, when producing an organic EL display device using the flexible device substrate of the present invention, it becomes possible to directly adhere the sealing member and the base material, It becomes possible to more firmly prevent moisture from entering the organic EL display device. In addition, by selectively forming the sealing part in the base material exposed region, it becomes possible to divide the organic EL display device in a plane or to seal it in a multi-faceted state with high productivity. There is an advantage that an element can be manufactured. The substrate exposed region can also be a through-hole for penetrating the planarizing layer and the adhesion layer and electrically conducting the substrate. In the present invention, that the planarizing layer is partially formed on the substrate means that the planarizing layer is not formed on the entire surface of the substrate. The planarization layer may be formed on the entire surface of the substrate except for the outer edge portion of the substrate, or may be further formed in a pattern on the substrate except for the outer edge portion of the substrate.

3. Other Configurations The flexible device substrate of the present invention may further have an adhesion layer containing an inorganic compound on the base material and the planarization layer. By providing the adhesion layer, a sufficient adhesion can be obtained between the flattening layer containing polyimide and the TFT produced on the flexible device substrate of the present invention, which is preferable.

  The adhesion layer preferably has the same surface smoothness as the planarization layer from the viewpoint of the electrical properties of the device. In addition, about the measuring method of the said surface roughness, it is the same as that of the measuring method of the surface roughness of the smooth layer mentioned above.

  The adhesion layer preferably has heat resistance. This is because when a TFT is produced on the flexible device substrate of the present invention, a high-temperature treatment is usually applied during the production of the TFT. As the heat resistance of the adhesion layer, the 5% weight reduction temperature of the adhesion layer is preferably 300 ° C. or more.

  In addition, about the measurement of 5% weight reduction | decrease temperature, using a thermal analyzer (DTG-60 (made by Shimadzu Corp.)), atmosphere: nitrogen atmosphere, temperature range: 30 degreeC-600 degreeC, temperature increase rate: Thermogravimetric / differential heat (TG-DTA) measurement was performed at 10 ° C./min, and the temperature at which the weight of the sample decreased by 5% was defined as a 5% weight reduction temperature (° C.).

  The adhesion layer usually has an insulating property. This is because when the TFT is produced on the flexible device substrate of the present invention, the flexible device substrate is required to have insulating properties.

  In the case where a TFT is produced on the flexible device substrate of the present invention, the adhesion layer is preferably one that prevents impurity ions contained in the planarization layer containing polyimide from diffusing into the semiconductor layer of the TFT. . Specifically, as the ion permeability of the adhesion layer, the iron (Fe) ion concentration is preferably 0.1 ppm or less, or the sodium (Na) ion concentration is preferably 50 ppb or less. In addition, as a measuring method of the density | concentration of Fe ion and Na ion, after sampling and extracting the layer formed on the contact | adherence layer, the method of analyzing by an ion chromatography method is used.

  The inorganic compound constituting the adhesion layer is not particularly limited as long as it satisfies the above-described characteristics. For example, silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, oxidation Examples thereof include chromium and titanium oxide. These may be one type or two or more types.

  The adhesion layer may be a single layer or a multilayer.

  When the adhesion layer is a multilayer film, a plurality of layers made of the above-described inorganic compound may be laminated, or a layer made of the above-mentioned inorganic compound and a layer made of metal may be laminated. The metal used in this case is not particularly limited as long as an adhesion layer that satisfies the above-described characteristics can be obtained, and examples thereof include chromium, titanium, aluminum, and silicon.

When the adhesion layer is a multilayer film, the outermost layer of the adhesion layer is preferably a silicon oxide film. That is, when a TFT is produced on the flexible device substrate of the present invention, it is preferable that the TFT is produced on a silicon oxide film. This is because the silicon oxide film sufficiently satisfies the above characteristics. The silicon oxide in this case is preferably SiO _x (X is in the range of 1.5 to 2.0).

  Among them, the adhesion layer is formed on the planarization layer and is selected from the group consisting of chromium, titanium, aluminum, silicon, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, aluminum oxynitride, chromium oxide, and titanium oxide. It is preferable to have a first adhesion layer made of at least one of the above and a second adhesion layer formed on the first adhesion layer and made of silicon oxide. The adhesion between the planarization layer and the second adhesion layer can be enhanced by the first adhesion layer, and the adhesion between the planarization layer and the TFT produced on the flexible device substrate of the present invention can be enhanced by the second adhesion layer. This is because it can be increased. Moreover, it is because the 2nd contact | adherence layer which consists of silicon oxides fully satisfy | fills the above-mentioned characteristic.

  The thickness of the adhesion layer is not particularly limited as long as it can satisfy the above-described characteristics, but specifically, it is preferably in the range of 1 nm to 500 nm. In particular, when the adhesion layer has the first adhesion layer and the second adhesion layer as described above, the second adhesion layer is thicker than the first adhesion layer, the first adhesion layer is relatively thin, and the second adhesion layer. Is preferably relatively thick. In this case, the thickness of the first adhesion layer is preferably in the range of 0.1 nm to 50 nm, more preferably in the range of 0.5 nm to 20 nm, and still more preferably in the range of 1 nm to 10 nm. The thickness of the second adhesion layer is preferably in the range of 10 nm to 500 nm, more preferably in the range of 50 nm to 300 nm, and still more preferably in the range of 80 nm to 120 nm. This is because if the thickness is too thin, sufficient adhesion may not be obtained, and if the thickness is too thick, cracks may occur in the adhesion layer.

  The adhesion layer may be formed on the entire surface of the base material or the planarization layer, or may be partially formed on the base material or the planarization layer. In particular, when the planarization layer is partially formed on the substrate as described later, it is preferable that the adhesion layer is also partially formed on the substrate in the same manner as the planarization layer. This is because if the adhesion layer containing the inorganic compound is formed directly on the substrate, cracks or the like may occur in the adhesion layer. That is, it is preferable that the adhesion layer and the planarization layer have the same shape.

  The method for forming the adhesion layer is not particularly limited as long as it is a method capable of forming a layer made of the above-described inorganic compound or a layer made of the above-mentioned metal. For example, DC (direct current) sputtering, RF (High frequency) magnetron sputtering method, plasma CVD (chemical vapor deposition) method, etc. can be mentioned. In particular, when a layer made of the above-described inorganic compound is formed and a layer containing aluminum or silicon is formed, it is preferable to use a reactive sputtering method. This is because a film having excellent adhesion to the planarizing layer can be obtained.

  In the present invention, an intermediate layer may be formed between the substrate and the planarization layer. For example, when using metal foil as a base material, the intermediate layer which consists of an oxide film in which the metal which comprises metal foil was oxidized may be formed between metal foil and the planarization layer. Thereby, the adhesiveness of metal foil and a planarization layer can be improved. This oxide film is formed by oxidizing the surface of the metal foil.

  Moreover, the said oxide film may be formed also in the surface on the opposite side to the surface in which the planarization layer of metal foil is formed.

4). TECHNICAL FIELD The present invention provides the above-described method for manufacturing a flexible device substrate, which includes an insulating layer forming step of forming an insulating layer by applying a polyimide resin composition on a base material by a die coating method. . In this invention, a polyimide resin composition shows the composition containing the above-mentioned polyimide or a polyimide precursor, and a solvent. The polyimide resin composition may contain additives such as a leveling agent, a plasticizer, a surfactant, and an antifoaming agent as necessary.

  Examples of the solvent used in the composition include ethers such as diethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether; ethylene glycol monomethyl ether, ethylene glycol Glycol monoethers (so-called cellosolves) such as monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether; methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, etc. Ketones; ethyl acetate, acetic acid Chill, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, acetate esters of the glycol monoethers (for example, methyl cellosolve acetate, ethyl cellosolve acetate), methoxypropyl acetate, ethoxypropyl acetate, Esters such as dimethyl oxalate, methyl lactate, ethyl lactate; alcohols such as ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, diethylene glycol, glycerin; methylene chloride, 1,1-dichloroethane, 1,2-dichloroethylene, Halogenated hydrocarbons such as 1-chloropropane, 1-chlorobutane, 1-chloropentane, chlorobenzene, bromobenzene, o-dichlorobenzene, m-dichlorobenzene; N, N- Amides such as methylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide; Pyrrolidones such as N-methylpyrrolidone; Lactones such as γ-butyrolactone; Sulfoxides such as dimethylsulfoxide And other organic polar solvents, and aromatic hydrocarbons such as benzene, toluene, and xylene, and other organic nonpolar solvents. These solvents are used alone or in combination.

  In addition, when the polyimide resin composition is applied by the die coating method, depending on the solubility of the polyimide precursor, if the solvent evaporates in the flow path, the polyimide precursor is precipitated, which causes deterioration of the surface flatness. There is a case. Also. If drying starts immediately after application, drying unevenness occurs, which may cause deterioration of surface flatness. From this point of view, it is preferable to use a solvent having a relatively high boiling point, specifically, the boiling point is preferably 100 ° C. or higher.

  In addition, a polyimide precursor having a molecular weight of 2,000 or more has a lower solvent solubility than a polyimide precursor having a molecular weight of less than 2,000. Therefore, N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexa Polar solvents such as methylphosphoamide, N-acetyl-2-pyrrolidone, pyridine, dimethyl sulfone, tetramethylene sulfone, dimethyltetramethylene sulfone, diethylene glycol dimethyl ether, cyclopentanone, γ-butyrolactone, α-acetyl-γ-butyrolactone It is mentioned as a suitable thing. In particular, N-methyl-2-pyrrolidone, N, N-dimethylformamide, and N, N-dimethylacetamide are preferable from the viewpoint of solubility.

  In the present invention, very high surface smoothness can be obtained by applying the resin composition containing polyimide described above by a die coating method. In addition, when apply | coating a polyimide solution or a polyimide precursor solution, the fluidity | liquidity of a film | membrane can be improved and smoothness can also be improved by heating more than the glass transition temperature of a polyimide or a polyimide precursor after application | coating.

  Here, the die coating method refers to a method of coating the base material by disposing the die head so as to face the base material and discharging the coating liquid from the die head while moving the die head relative to the base material. . FIG. 3 shows an outline of the die coating method. In the die coating method, the die head 5 is disposed facing the running substrate 2 (a), or the die head 5 is moved while being disposed facing the fixed substrate 2 (b). The coating is applied to the base material by discharging the coating liquid 6 from 5 at a constant width. Usually, since the coating liquid 6 is discharged from the slit part of the die head 5, a method called a slit coating method can also be included in the die coating method of the present invention. A flattening layer is formed by curing the coating film applied by the die coating method. The curing method is not particularly limited, and methods known in the technical field to which the present invention belongs can be widely adopted. Here, since die coating is one of the pre-measuring applications in which 100% of the coating liquid supplied to the coating head is applied to the substrate, excess coating liquid and liquid circulation do not occur. Since it is possible to stably supply the coating liquid, it is possible to suppress changes in the film with respect to the coating direction of the substrate, which is preferable from the viewpoint of improving the surface flatness. Moreover, since it is possible to spread the coating liquid uniformly in the width direction by the die head portion, it is possible to suppress the change of the film with respect to the width direction of the base material, which is preferable from the viewpoint of improving the surface flatness. .

  As another method for forming a film by coating, a spin coating method is known. When a rigid substrate such as a glass substrate is used and a low-viscosity solution is used, a smooth surface can be formed even by using a spin coating method.

  However, for this project, since a flexible substrate is used, it is difficult to stably rotate the base material, and it is difficult to lower the viscosity of the solution due to the relationship between the film properties and the formed film thickness. Therefore, it is difficult to form a coated surface with high surface flatness using the spin coat method.

The conditions of the die coating method in an exemplary embodiment of the present invention are shown below, but the method of the present invention is not limited to the following conditions:
The slit width of the die head is preferably about 0.02 to 3 mm, although it depends on the applied film thickness.

  The positional relationship between the die head and the substrate is not particularly limited. When the die head coating portion is directed downward, the die head and the substrate may be relatively separated from each other and the coating liquid may be dropped from above. Alternatively, the coating solution may be applied from the upper side to the base material so that the die head and the base material are closer to each other. Moreover, when directing the coating part of a die head upward, it can apply, after arrange | positioning a base material on the upper part of a die head in the state which made the die head and the base material approach. In addition, when the coating portion of the die head is directed in the horizontal direction as well as in the oblique direction, the base material can be disposed and applied so as to have the same positional relationship as in the upward direction. The distance between the base material and the tip of the die head can be applied by dropping freely from about 1 cm to 100 cm like curtain coat when dripping from the upper surface, but the surface flatness of the resulting coating film From a viewpoint, it is preferable to apply in a state where the die head and the base material are close to each other, and specifically, 0.01 mm or more and 5 mm or less are preferable. Even when the coating part of the die head is directed to the direction other than the upward direction, it is preferably 0.01 mm or more and 5 mm or less. The relative speed between the substrate and the die head is preferably 0.1 to 500 m / min.

  As described above, it is preferable to use a polar solvent from the viewpoint of the solubility of polyimide, but the polar solvent tends to easily attack the resin article. However, since the die head is mainly composed of metal and is not affected by a polar solvent, it is preferable because it can be stably applied.

  The viscosity of the polyimide resin composition applied by the die coating method is preferably 1 to 50,000 cP, more preferably 100 to 40,000 cP, and even more preferably 300 to 30,000. In terms of physical properties, it is necessary to keep the molecular weight at 2,000 or more. Furthermore, the polar solvents listed above have a higher viscosity than other solvents (ketone-based and alcohol-based), so it is difficult to lower the viscosity. This is because it is difficult to obtain a desired film thickness when the viscosity is lowered by lowering the solid content. If the viscosity is low, the surface of the film may be roughened during drying. On the other hand, if the viscosity is too high, it is difficult to uniformly extrude from the slit and the surface flatness is impaired.

  The solid content of the polyimide precursor is preferably 5% or more and less than 50%. When the solid content is too low, it is difficult to make the viscosity within the above-mentioned preferable range, and the film thickness becomes thin due to the volatilization of the solvent, and it is difficult to obtain a desired film thickness. On the other hand, if the solid content is too high, it is difficult to make the viscosity within the above-mentioned preferable range, and from the viewpoint of solubility in a solvent, the amount that can be dissolved is a substantial upper limit. Further, from the viewpoint of obtaining a viscosity region suitable for the above-described die coating, the number average molecular weight of polyimide is more preferably 4000 or more and 500,000 or less.

  In the present invention, the polyimide resin composition may be degassed before coating. In the embodiment, for example, the polyimide resin composition is degassed so that the relative dissolved oxygen saturation rate becomes 95% or less. Here, the relative dissolved oxygen saturation is measured as follows. First, using a dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in a solvent contained in the polyimide resin composition, the measured value of the dissolved oxygen amount of the solvent in which no oxygen is dissolved is 0, and the dissolved oxygen saturated solvent The dissolved oxygen meter is calibrated so that the measured value of the dissolved oxygen amount becomes 100. Next, using the calibrated dissolved oxygen meter, the relative value of the dissolved oxygen amount of the reference polyimide resin composition in which the polyimide resin composition was allowed to stand for 1 hour or more in the atmosphere, and the degassing that degassed the polyimide resin composition. The relative value of the dissolved oxygen amount of the gas polyimide resin composition is measured. And the relative value of the dissolved oxygen amount of the said deaeration polyimide resin composition when the relative value of the dissolved oxygen amount of the said reference | standard polyimide resin composition is set to 100% is made into a relative dissolved oxygen saturation rate.

  Here, the bubbles in the liquid are in a state where the gas remains in a gaseous state and is mixed in the liquid. This foam is not only mixed from the outside, but is very often generated from the liquid. On the other hand, dissolved gas means a gas dissolved in a liquid, which cannot be seen with eyes like bubbles. The present invention removes the “dissolved gas” in the liquid.

  The amount of gas dissolved in the liquid varies depending on the type of liquid, temperature and pressure, and the wetted material, and dissolved gas above the saturation amount appears as bubbles. That is, even if the liquid is free of bubbles, bubbles are generated when the temperature, pressure, or the like changes. On the other hand, even if bubbles are present in the liquid, if the temperature is a predetermined temperature or pressure, or if the dissolved amount of the gas is less than the saturation value, the bubbles are not dissolved in the liquid. That is, it is not sufficient to simply remove bubbles, and it is important to remove dissolved gas.

  Therefore, when the polyimide resin composition is in contact with the atmosphere for a sufficient amount of time and the air is constantly dissolved in the polyimide resin composition, a dissolved gas above the saturation amount is generated as a bubble with a slight change in pressure or temperature. It is expected that However, when the dissolved gas amount of the polyimide resin composition in a state where air is constantly dissolved is 100%, when the dissolved gas amount of the polyimide resin composition is about 95%, the pressure and temperature change. Since it does not immediately exceed the saturation amount of the dissolved gas, generation of bubbles can be suppressed.

  With respect to the dissolved gas, in the situation where the polyimide resin composition is in contact with the atmosphere, most of the gas dissolved in the polyimide resin composition is nitrogen or oxygen (the amount in the atmosphere is next to oxygen) Argon is less than 1/20 of oxygen). Nitrogen is an inert gas and is difficult to measure, but oxygen is measurable. In addition, for many solvents, the ratio of the solubility of oxygen and nitrogen in the solvent at the same temperature and pressure is 1.4 to 2.0 (oxygen is easier to dissolve), and the partial pressure of nitrogen in the atmosphere Is about 3.7 times higher than the partial pressure of oxygen. From Henry's law, it is considered that nitrogen is dissolved about 1.9 to 2.7 times that of oxygen when in contact with the atmosphere. This ratio is constant in the state where the pressure is not high as long as the type of the solvent is the same, and even if the type of the solvent is changed, the fluctuation range is not so large as about 1.9 to 2.7 times. By determining the amount, it is possible to estimate the amount of dissolved gas that combines nitrogen and oxygen.

  It is difficult to measure the absolute value of dissolved oxygen in a solvent other than water. Therefore, in the present invention, the relative value (relative dissolved oxygen saturation) is evaluated based on the dissolved oxygen amount of the dissolved oxygen saturated solvent in which air is bubbled for 30 minutes or more in the solvent contained in the polyimide resin composition.

  When an insulating layer is formed by applying a polyimide resin composition, a skin layer is formed on the surface of the coating film when the polyimide resin composition is applied and dried, and it is difficult for the solvent and water to evaporate, It may become difficult to detach. Therefore, if bubbles are included in the polyimide resin composition or a gas is dissolved in the polyimide resin composition, an insulating layer that encloses the bubbles is formed.

  On the other hand, in the embodiment including the degassing step, the polyimide resin composition is degassed before forming the insulating layer, so that bubbles in the insulating layer can be reduced. In particular, since the polyimide resin composition is deaerated so that the relative dissolved oxygen saturation calculated by a predetermined method is 95% or less, not only micrometer-order bubbles but also nanometer-order bubbles are reduced in the insulating layer. can do. Thereby, it is possible to form an insulating layer having excellent surface smoothness. In addition, even when unevenness is present on the surface of the base material, it is possible to flatten the unevenness on the surface of the base material by forming an insulating layer on the base material, improving the surface smoothness of the substrate for thin film elements can do. Therefore, a thin film element having good characteristics can be obtained by using the thin film element substrate manufactured according to the present invention.

5. Applications The substrate for flexible devices of the present invention can also be applied to TFT substrates, electrode substrates and the like. The electrode substrate can be used for a top emission type organic EL display device, and can be applied to lighting applications. Furthermore, the flexible device substrate of the present invention can also be applied to passive matrix electronic paper.

B. Next, the flexible device TFT substrate of the present invention (hereinafter sometimes simply referred to as a TFT substrate) will be described.

  The TFT substrate of the present invention has the above-mentioned flexible device substrate and a TFT formed on the adhesion layer of the flexible device substrate.

  In one embodiment, the TFT substrate of the present invention may include a TFT having a top gate / bottom contact structure on a flexible device substrate or a TFT having a top gate / top contact structure.

  According to the present invention, since the above-mentioned substrate for a flexible device is used, the unevenness on the substrate surface can be flattened by the flattening layer. Therefore, it is possible to suppress a decrease in the electrical performance of the TFT due to the unevenness. Moreover, according to this invention, since the above-mentioned substrate for flexible devices is used, it is excellent in the adhesiveness of the substrate for flexible devices and TFT. Therefore, even when moisture or heat is applied during the manufacture of the TFT substrate of the present invention and the dimensions of the planarization layer containing polyimide change, it is possible to prevent the electrodes and the semiconductor layer from peeling or cracking.

  Moreover, when using metal foil as a base material, the TFT substrate of the present invention has a gas barrier property against oxygen and water vapor. Therefore, when an organic EL display device is manufactured using the TFT substrate of the present invention, deterioration of element performance due to moisture and oxygen can be suppressed, and a liquid crystal display system using the flexible device substrate of the present invention. When the electronic paper is produced, the liquid crystal can be prevented from being exposed to water vapor. Furthermore, the TFT substrate of the present invention has a metal foil, and since the metal foil is generally excellent in thermal conductivity, it has heat dissipation. Therefore, when an organic EL display device is manufactured using the TFT substrate of the present invention, deterioration of element performance due to heat generation of the organic EL display device can be suppressed.

  In this embodiment, since the TFT substrate of the present invention is supported by a metal foil, a TFT substrate having excellent durability can be obtained.

  The flexible device substrate has been described in detail in the section “A. Flexible Device Substrate”, and the description thereof is omitted here. Hereinafter, another configuration of the TFT substrate of the present invention will be described.

  The TFT in the present invention is formed on the adhesion layer of the flexible device substrate.

  Examples of the TFT structure include a top gate structure (forward stagger type), a bottom gate structure (reverse stagger type), and a coplanar type structure. In the case of the top gate structure (forward stagger type) and the bottom gate structure (reverse stagger type), a top contact structure and a bottom contact structure can be further exemplified. These structures are appropriately selected according to the type of semiconductor layer constituting the TFT.

  The semiconductor layer constituting the TFT is not particularly limited as long as it can be formed on the flexible device substrate. For example, silicon, an oxide semiconductor, or an organic semiconductor is used.

  As the silicon, polysilicon or amorphous silicon can be used.

Examples of the oxide semiconductor include zinc oxide (ZnO), titanium oxide (TiO), magnesium zinc oxide (Mg _x Zn _1-x O), cadmium zinc oxide (Cd _x Zn _1-x O), and cadmium oxide (CdO). ), Indium oxide (In ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), tin oxide (SnO ₂ ), magnesium oxide (MgO), tungsten oxide (WO), InGaZnO-based, InGaSnO-based, InGaZnMgO-based, InAlZnO-based InFeZnO, InGaO, ZnGaO, and InZnO can be used.

  Examples of the organic semiconductor include a π-electron conjugated aromatic compound, a chain compound, an organic pigment, and an organosilicon compound. More specifically, pentacene, tetracene, thiophen oligomer derivatives, phenylene derivatives, phthalocyanine compounds, polyacetylene derivatives, polythiophene derivatives, cyanine dyes and the like can be mentioned.

  Especially, it is preferable that a semiconductor layer is an oxide semiconductor layer which consists of the above-mentioned oxide semiconductor. Although the electrical characteristics of an oxide semiconductor change due to the influence of water and oxygen, since the TFT substrate of the present invention has a gas barrier property against water vapor as described above, it is possible to suppress deterioration in characteristics of the semiconductor. For example, when the TFT substrate of the present invention is used for an organic EL display device and a metal foil is used as a base material, the organic EL display device is inferior in resistance to water and oxygen, but the metal foil transmits oxygen and water vapor. Since it can suppress, degradation of element performance can be suppressed.

  The method for forming the semiconductor layer and the thickness thereof can be the same as those in general.

  The gate electrode, source electrode, and drain electrode constituting the TFT are not particularly limited as long as they have desired conductivity, and a conductive material generally used for TFTs can be used. Examples of such materials include Ta, Ti, Al, Zr, Cr, Nb, Hf, Mo, Au, Ag, Pt, Mo-Ta alloys, W-Mo alloys, ITO, IZO and other inorganic materials, and And organic materials having conductivity such as PEDOT / PSS.

  The formation method and thickness of the gate electrode, the source electrode, and the drain electrode can be the same as those in general.

  As the gate insulating film constituting the TFT, the same gate insulating film as that in a general TFT can be used. For example, silicon oxide, silicon nitride, aluminum oxide, tantalum oxide, barium strontium titanate (BST), Insulating inorganic materials such as lead zirconate titanate (PZT), acrylic resins, phenolic resins, fluorine resins, epoxy resins, cardo resins, vinyl resins, imide resins, novolac resins, etc. An insulating organic material can be used.

  The formation method and thickness of the gate insulating film can be the same as a general one.

  A protective film may be formed on the TFT. The protective film is provided to protect the TFT. For example, the semiconductor layer can be prevented from being exposed to moisture or the like contained in the air. By forming the protective film, deterioration of the TFT performance with time can be reduced. Examples of such protective films include insulating inorganic materials such as silicon oxide and silicon nitride, and acrylic resins, phenolic resins, fluorine resins, epoxy resins, cardo resins, vinyl resins, and imide resins. An insulating organic material such as resin or novolac resin is used.

  The method for forming the protective film and the thickness thereof can be the same as those in general.

  When the semiconductor layer is an oxide semiconductor layer, if a protective film is formed over the oxide semiconductor layer by a sputtering method or the like, oxygen may be lost in the oxide semiconductor, but in the presence of oxygen after the protective film is formed, By performing the annealing treatment, oxygen defects can be compensated. Since this annealing process is performed at a high temperature of several hundred degrees, there is a concern about the dimensional change of the planarizing layer containing polyimide. However, in the present invention, since the adhesion layer is formed, the dimension of the planarizing layer is reduced by the annealing process. Even if it is changed, the adhesion between the planarization layer and the TFT can be maintained, and peeling and cracking of the TFT can be suppressed.

C. Next, the flexible device of the present invention will be described.

  A flexible device according to the present invention includes the above-described TFT substrate.

  According to the present invention, since the above-described TFT substrate is used, the electrical performance of the TFT is prevented from being deteriorated due to the unevenness of the base material surface, and the electrode or the semiconductor layer is peeled or cracked when the flexible device of the present invention is manufactured or used. Can be prevented.

  In addition, when the flexible device of the present invention is an organic EL display device, the flexible device substrate has a gas barrier property against water vapor and oxygen, so that an organic EL display device with good element performance can be obtained. Furthermore, when the flexible device of the present invention is an organic EL display device, the flexible device substrate has heat dissipation properties, so that performance degradation due to heat generation of the organic EL display device can be suppressed.

  Moreover, in embodiment using metal foil as a base material, since a flexible device is supported by metal foil, it can be set as the flexible device excellent in durability.

  The flexible device of the present invention is not particularly limited as long as it is a device having a TFT and having flexibility, but among them, a flexible display is preferable. Examples of flexible displays include organic EL display devices, electronic paper, and reflective liquid crystal display devices. In particular, the flexible device of the present invention is preferably an organic EL display device or electronic paper. Other than the flexible display, a circuit such as an RFID and a sensor can be exemplified.

  The organic EL display device is described in detail in the section “D. Organic EL display device” described later, and the electronic paper is described in detail in the section “E. Electronic paper” described later. Is omitted. Further, the TFT substrate is described in detail in the section “B. TFT substrate for flexible device”, and therefore the description thereof is omitted here.

D. Organic EL Display Device The organic EL display device of the present invention includes the above-described TFT substrate, that is, includes the above-described flexible device substrate. Specifically, the organic EL display device of the present invention is a flexible substrate having a base material, a flattening layer formed on the base material and containing polyimide, and an adhesion layer formed on the flattening layer and containing an inorganic compound. A device substrate, a back electrode layer and TFT formed on the adhesion layer of the flexible device substrate, an EL layer formed on the back electrode layer and including at least an organic light emitting layer, and formed on the EL layer And a transparent electrode layer formed.

  In a typical embodiment, the organic EL display device of the present invention includes a flexible device substrate having the above-described adhesion layer, a driving TFT and a switching TFT formed on the adhesion layer of the flexible device substrate, A protective film formed to cover the TFT for switching and the switching TFT, and a back electrode layer (pixel electrode) formed on the protective film and electrically connected to the drain electrode of the driving TFT through a through hole And an EL layer formed on the back electrode layer and including an organic light emitting layer, and a transparent electrode layer formed on the EL layer. The board | substrate for flexible devices has a base material, the planarization layer which is formed on a base material and contains a polyimide, and the contact | adherence layer which is formed on a planarization layer and contains an inorganic compound. Each of the driving TFT and the switching TFT has a bottom gate / top contact structure, and includes a gate electrode formed on the adhesion layer of the flexible device substrate, a gate insulating film formed on the gate electrode, and gate insulation. A semiconductor layer formed on the film and a source electrode and a drain electrode are included.

  According to the present invention, since the flexible device substrate described above is used, it is possible to prevent deterioration of the electrical performance of the TFT due to irregularities on the surface of the base material, and to peel off the TFT during manufacturing or use of the organic EL display device of the present invention. Cracks can be prevented from occurring. Moreover, since the substrate for flexible devices has a gas barrier property against water vapor and oxygen, the element performance can be maintained satisfactorily. Furthermore, since the flexible device substrate has heat dissipation, it is possible to suppress performance deterioration due to heat generation of the organic EL display device. Moreover, when using metal foil as a base material, since the organic EL display device of the present invention is supported by metal foil, it can be excellent in durability.

  The flexible device substrate has been described in detail in the section “A. Flexible Device Substrate”, and the description thereof is omitted here. Hereinafter, another configuration of the organic EL display device of the present invention will be described.

1. TFT
The TFT in the present invention is formed on the adhesion layer of the flexible device substrate. In general, in an organic EL display device, two TFTs, a driving TFT and a switching TFT, are provided for each pixel.

  Since the TFT is described in the section “B. TFT substrate for flexible device”, description thereof is omitted here.

2. Back Electrode Layer The back electrode layer in the present invention is a pixel electrode that is formed on the adhesion layer of the flexible device substrate and is electrically connected to the drain electrode of the TFT.

  The material of the back electrode layer is not particularly limited as long as it is a conductive material. For example, Au, Ta, W, Pt, Ni, Pd, Cr, Cu, Mo, alkali metal, alkaline earth metal, etc. Simple metals, oxides of these metals, Al alloys such as AlLi, AlCa, AlMg, Mg alloys such as MgAg, alloys such as Ni alloys, Cr alloys, alkali metal alloys, alkaline earth metal alloys, etc. Can be mentioned. These conductive materials may be used alone, in combination of two or more kinds, or may be laminated using two or more kinds. In addition, conductive oxides such as indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, zinc oxide, indium oxide, and aluminum zinc oxide (AZO) can also be used.

  The formation method and thickness of the back electrode layer can be the same as those of an electrode in a general organic EL display device.

3. EL layer The EL layer in the present invention is formed on the back electrode layer, includes an organic light emitting layer, and has one or more organic layers including at least the organic light emitting layer. That is, the EL layer is a layer including at least an organic light-emitting layer, and the layer configuration is a layer having one or more organic layers. Usually, when forming an EL layer by a coating method, it is difficult to stack a large number of layers in relation to the solvent, so the EL layer often has one or two organic layers, It is possible to further increase the number of layers by devising an organic material so that the solubility in a solvent is different or by combining a vacuum deposition method.

  Examples of the layer formed in the EL layer other than the organic light emitting layer include a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer. The hole injection layer and the hole transport layer may be integrated. Similarly, the electron injection layer and the electron transport layer may be integrated. In addition, the layer formed in the EL layer can be re-used by preventing holes or electrons from penetrating like the carrier block layer, and further preventing diffusion of excitons and confining excitons in the light emitting layer. Examples thereof include a layer for increasing the coupling efficiency.

  Thus, the EL layer often has a laminated structure in which various layers are laminated, and there are many types of laminated structures.

  Each layer constituting the EL layer can be the same as that used in a general organic EL display device.

4). Transparent electrode layer The transparent electrode layer in this invention is formed on an EL layer. In the organic EL display device of the present invention, since the light is extracted from the transparent electrode layer side, the transparent electrode layer has transparency.

  The material for the transparent electrode layer is not particularly limited as long as it is a conductive material capable of forming a transparent electrode. For example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide, zinc oxide, A conductive oxide such as indium oxide or zinc aluminum oxide (AZO) can be used.

  The formation method and thickness of the transparent electrode layer can be the same as those of an electrode in a general organic EL display device.

5. Other Configurations The organic EL display device of the present invention may include an insulating layer, a partition wall, a sealing member, and the like as necessary in addition to the above-described configuration.

E. Electronic Paper The electronic paper of the present invention includes the above-described TFT substrate, that is, includes the above-described flexible device substrate. Specifically, the electronic paper of the present invention is for a flexible device having a base material, a flattening layer formed on the base material and containing polyimide, and an adhesion layer formed on the flattening layer and containing an inorganic compound. A substrate, a back electrode layer and a TFT formed on the adhesion layer of the flexible device substrate, a display layer formed on the back electrode layer, and a transparent electrode layer formed on the display layer It is characterized by this.

  In a typical embodiment, the electronic paper of the present invention includes a flexible device substrate having the adhesion layer described above, a TFT formed on the adhesion layer of the flexible device substrate, and a protection formed to cover the TFT. A film, a back electrode layer (pixel electrode) formed on the protective film and electrically connected to the drain electrode of the TFT through the through hole, a display layer formed on the back electrode layer, and the display layer And a transparent electrode layer formed on the substrate. The board | substrate for flexible devices has a base material, the planarization layer which is formed on a base material and contains a polyimide, and the contact | adherence layer which is formed on a planarization layer and contains an inorganic compound. The TFT has a bottom gate / top contact structure, a gate electrode formed on the adhesion layer of the flexible device substrate, a gate insulating film formed on the gate electrode, and a semiconductor layer formed on the gate insulating film. And a source electrode and a drain electrode.

  According to the present invention, since the substrate for a flexible device described above is used, the electrical performance of the TFT is prevented from being deteriorated due to the unevenness of the surface of the base material, and peeling or cracking is caused in the TFT when the electronic paper of the present invention is manufactured or used. It can be prevented from occurring. Moreover, when using metal foil as a base material, since the electronic paper of this invention is supported by metal foil, it can be made excellent in durability.

  As a display method of electronic paper, known ones can be applied, for example, electrophoresis method, twist ball method, powder movement method (electronic powder fluid method, charged toner type method), liquid crystal display method, thermal method. (Coloring method, light scattering method), electrodeposition method, movable film method, electrochromic method, electrowetting method, magnetophoresis method and the like.

  The display layer constituting the electronic paper is appropriately selected according to the display method of the electronic paper.

  The back electrode layer and the transparent electrode layer can be the same as the back electrode layer and the transparent electrode layer in the organic EL display device.

  The flexible device substrate is described in detail in the section “A. Flexible device substrate”, and the TFT is described in the section “B. TFT substrate for flexible device”. To do.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be specifically described using examples and comparative examples.

[Production example]
1. Preparation of polyimide precursor solution (Production Example 1)
4.0 g (20 mmol) of 4,4′-diaminodiphenyl ether (ODA) and 8.65 g (80 mmol) of paraphenylenediamine (PPD) were put into a 500 ml separable flask, and 200 g of dehydrated N-methyl-2 was added. -It dissolved in pyrrolidone (NMP), and it stirred, heating and monitoring with a thermocouple so that liquid temperature might be 50 degreeC with an oil bath under nitrogen stream. After confirming that they were completely dissolved, 29.1 g (99 mmol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was added thereto gradually over 30 minutes. After completion of the addition, the mixture was stirred at 50 ° C. for 5 hours. Then, it cooled to room temperature and obtained the polyimide precursor solution 1.

(Production Example 2)
The polyimide precursor solution 2 was prepared in the same manner as in Production Example 1, except that the amount of NMP was adjusted so that the reaction temperature and the solution concentration were 17% by weight to 19% by weight, with the compounding ratio shown in Table 1 below. ~ 17 were synthesized.

  Acid dianhydrides include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), p-phenylenebistrimellitic acid monoester dianhydride (TAHQ), p-biphenylenebistrimellitic acid monoester dianhydride (BPTME) was used. Diamines include 4,4'-diaminodiphenyl ether (ODA), paraphenylenediamine (PPD), 1,4-Bis (4-aminophenoxy) benzene (4APB), 2,2'-Dimethyl-4,4'-diaminobiphenyl. One or two of (TBHG) and 2,2′-Bis (trifluoromethyl) -4,4′-diaminobiphenyl (TFMB) were used.

(Production Example 3)
In order to obtain a photosensitive polyimide, {[(4,5-dimethoxy-2-nitrobenzyl) oxy] carbonyl} 2,6-dimethyl piperidine (DNCDP) is added to the polyimide precursor solution 11 at a solid content of 15% by weight. It added and it was set as the photosensitive polyimide precursor solution 1.

(Production Example 4)
In order to obtain a photosensitive polyimide, an amide compound (HMCP) synthesized from 2-hydroxy-5-methoxy-cinnamic acid and piperidine was added to the polyimide precursor solution 1 at 10% by weight of the solid content of the solution. A polyimide precursor solution 2 was obtained.

(Production Example 5)
In order to obtain a photosensitive polyimide, an amide compound (HMCP) synthesized from 2-hydroxy-5-methoxy-cinnamic acid and piperidine was added to the polyimide precursor solution 11 at a solid content of 15% by weight. A polyimide precursor solution 3 was obtained.

(Evaluation of linear thermal expansion coefficient and hygroscopic expansion coefficient)
The polyimide precursor solutions 1 to 17 are applied to a heat-resistant film (Upilex S 50S: manufactured by Ube Industries, Ltd.) pasted on glass, dried on a hot plate at 80 ° C. for 10 minutes, and then heat-resistant film. Was peeled off to obtain a film having a film thickness of 15 to 20 μm. Thereafter, the film is fixed to a metal frame, heat-treated at 350 ° C. for 1 hour in a nitrogen atmosphere (temperature increase rate: 10 ° C./min, spontaneous cooling), polyimides 1 to 17 having a film thickness of 9 μm to 15 μm, and photosensitive Films of conductive polyimides 1 to 3 were obtained.

<Linear thermal expansion coefficient>
The film produced by the above method was cut into a width of 5 mm and a length of 20 mm and used as an evaluation sample. The linear thermal expansion coefficient was measured by a thermomechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation). The measurement conditions are as follows: the observation length of the evaluation sample is 15 mm, the heating rate is 10 ° C./min, the tensile load is 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample is the same, and 100 ° C. to 200 ° C. The average linear thermal expansion coefficient in the range was defined as the linear thermal expansion coefficient (CTE).

<Humidity expansion coefficient>
The film produced by the above method was cut into a width of 5 mm and a length of 20 mm and used as an evaluation sample. The humidity expansion coefficient was measured by a humidity variable mechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation). The temperature is kept constant at 25 ° C., and the sample is first stabilized in a humidity of 15% RH. After maintaining this state for approximately 30 minutes to 2 hours, the humidity of the measurement site is set to 20% RH. Further, this state was maintained for 30 minutes to 2 hours until the sample became stable. Thereafter, the humidity is changed to 50% RH, and the difference between the sample length when the humidity becomes stable and the sample length when the humidity becomes stable at 20% RH is expressed as a change in humidity (in this case, 50-20). 30), and the value divided by the sample length was defined as the humidity expansion coefficient (CHE). At this time, the tensile load was set to 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample was the same.

(Substrate warpage evaluation)
Sample preparation for linear thermal expansion coefficient evaluation using the above polyimide precursor solution 1 on a SUS304-HTA foil (manufactured by Toyo Seiki Co., Ltd.) having a thickness of 18 μm so that the film thickness after imidation becomes 10 μm ± 1 μm A polyimide film of polyimide 1 was formed under the same process conditions. Then, the laminated body of SUS304 foil and a polyimide film was cut | disconnected to width 10mm x length 50mm, and it was set as the sample for board | substrate curvature evaluation.

  This sample was fixed to the SUS plate surface with only one of the short sides of the sample with Kapton tape, heated in an oven at 100 ° C. for 1 hour, and then in the oven heated to 100 ° C., the short side on the opposite side of the sample The distance from the SUS plate was measured. At that time, a sample having a distance of 0 mm or more and 0.5 mm or less was evaluated as “◯”, a sample of more than 0.5 mm and 1.0 mm or less was evaluated as Δ, and a sample of 1.0 mm or more was determined as “X”.

  Similarly, when this sample is fixed to the surface of the SUS plate with only one of the short sides of the sample with Kapton tape and left in a constant temperature and humidity chamber at 23 ° C. and 85% Rh for 1 hour, The distance from the short side SUS plate was measured. At that time, a sample having a distance of 0 mm or more and 0.5 mm or less was evaluated as “◯”, a sample of more than 0.5 mm and 1.0 mm or less was evaluated as Δ, and a sample of 1.0 mm or more was determined as “X”.

  Next, instead of 18 μm thick SUS304-HTA foil (manufactured by Toyo Seiki), 20 μm thick SUS430 foil (manufactured by Toyo Seiki) is used, and instead of polyimide precursor solution 1, polyimide precursor solution 2 is used. The substrate warpage was evaluated in the same manner as above.

  The evaluation results are shown below.

(Number average molecular weight)
The number average molecular weights of polyimides 1 and 2 were measured using a nuclear magnetic resonance spectrum, and both were about 20000.

(viscosity)
Using a digital viscometer TVE-22HT type (manufactured by Toki Sangyo Co., Ltd.), the viscosity of polyimides 1 and 2 is: rotor: 3 ° × R17.65, measurement range: R, rotation speed: 10 rpm, temperature: 25 ° C. As a result, both were about 5000 cps.

2. Formation of planarization layer (insulating layer) (Formation of planarization layer (insulating layer) 1)
After coating the polyimide precursor solution 1 with a die coater on SUS304-HTA foil (manufactured by Toyo Seiki Co., Ltd.) having a thickness of 18 μm cut into a 16 cm square, and drying it in the atmosphere at 80 ° C. for 60 minutes. Then, heat treatment was performed at 350 ° C. for 1 hour in a nitrogen atmosphere (temperature increase rate: 10 ° C./min, natural cooling) to form a polyimide film with a film thickness of 9 μm, and a laminate 1 was obtained.

(Formation of flattening layer (insulating layer) 2)
Polyimide film with a thickness of 20 μm cut into 16 cm square: Kapton 80EN (manufactured by Toray DuPont) is coated with the above polyimide precursor solution 1 with a die coater and dried in an oven at 80 ° C. for 60 minutes in the air. After that, heat treatment was performed at 350 ° C. for 1 hour in a nitrogen atmosphere (temperature increase rate: 10 ° C./min, natural cooling) to form a 9 μm-thick polyimide film, whereby a laminate 2 was obtained.

(Formation of flattening layer (insulating layer) 3)
A SUS304-HTA foil having a thickness of 18 μm cut into a 9 cm square was attached to a 10 cm square glass plate (thickness: 0.7 mm) using a Kapton tape. A laminate 3 was obtained in the same manner as in the flattening layer (insulating layer) formation 1 except that the polyimide precursor solution 1 was coated by spin coating.

(Flatness evaluation)
The surface roughness Ra of the polyimide (PI) application surface and SUS foil and polyimide film: Kapton 80EN of the laminated bodies 1-3 was measured.

  First, using Nanoscope V multimode (manufactured by Veeco), in tapping mode, the cantilever: MPP11100, scanning ranges: 10 μm × 10 μm and 1 μm × 1 μm, scanning speed: 0.5 Hz, the surface shape is imaged and obtained. The surface roughness Ra of the laminate 1 was determined by calculating the average deviation from the center line of the roughness curve calculated from the obtained image. Next, using a New View 5000 (manufactured by Zygo), a surface shape in the range of 100 μm × 100 μm was imaged with an objective lens: 100 ×, a zoom lens: 1 ×, and a Scan Length: 15 μm. The surface roughness Ra of the laminate 1 was determined by calculating the average deviation from the center line of the calculated roughness curve.

  The surface roughness Ra of the laminates 1 to 3 and the SUS foil is shown below:

  As shown in Table 4, the substrate coated with die coating has a surface roughness Ra of 5 μm or less at the measurement area of 10 μm square and 1 μm on the surface of the flattened layer, and is very smooth. In contrast, the substrate coated with spin coating has a large Ra. In such a substrate, the electrical properties are lowered due to the unevenness of the surface, and as a result, the yield of device manufacturing is lowered.

[Production Example 1] Method for producing TFT substrate and full-color EL display A TFT substrate and a full-color EL display can be produced by the following method:
After immersing in 10% sulfuric acid (v / v) for 1 minute, the polyimide precursor was washed on a 100 μm thick SUS304-HTA plate (manufactured by Koyama Steel Co., Ltd.) washed with pure water and pickled by drying. The body solution 1 was coated with a die coater so that the film thickness after imidization was 7 μm ± 1 μm, dried in the air in a hot plate oven at 100 ° C. for 60 minutes, and then in a nitrogen atmosphere, 350 Heat treatment is performed at 1 ° C. for 1 hour (temperature increase rate: 10 ° C./min, natural cooling) to form a planarization layer.

  Next, an aluminum film as a first adhesion layer was formed on the planarizing layer with a thickness of 5 nm by a DC sputtering method (deposition pressure 0.2 Pa (argon), input power 1 kW, deposition time 10 seconds). Next, a silicon oxide film as a second adhesion layer is formed with a thickness of 100 nm by an RF magnetron sputtering method (deposition pressure 0.3 Pa (argon: oxygen = 3: 1), input power 2 kW, deposition time 30 minutes). . Thereby, the board | substrate for flexible devices can be obtained.

A TFT having a bottom gate / bottom contact structure is fabricated on the flexible device substrate. First, after forming an aluminum film having a thickness of 100 nm as a gate electrode film, a resist pattern is formed by a photolithography method, then wet etching is performed with a phosphoric acid solution, and the aluminum film is patterned into a predetermined pattern to form a gate electrode. Next, silicon oxide having a thickness of 300 nm was formed as a gate insulating film on the entire surface so as to cover the gate electrode. This gate insulating film uses an RF magnetron sputtering apparatus and is applied to a 6-inch SiO ₂ target with a power of 1.0 kW (= 3 W / cm ² ), a pressure of 1.0 Pa, and a gas of argon + O ₂ (50%). The film is formed under film forming conditions. Thereafter, after forming a resist pattern by a photolithography method, dry etching is performed to form a contact hole. Next, a 100 nm thick titanium film, aluminum film, and IZO film are deposited on the entire surface of the gate insulating film to form a source electrode and a drain electrode, and then a resist pattern is formed by a photolithography method, and then a hydrogen peroxide solution is formed. Then, wet etching is continuously performed with a phosphoric acid solution, and the titanium film is patterned into a predetermined pattern to form a source electrode and a drain electrode. At this time, the source electrode and the drain electrode are formed on the gate insulating film so as to have a pattern apart from a portion other than directly above the central portion of the gate electrode.

Next, an InGaZnO-based amorphous oxide thin film (InGaZnO ₄ ) with an In: Ga: Zn ratio of 1: 1: 1 is formed on the entire surface so as to cover the source electrode and the drain electrode so as to have a thickness of 25 nm. The amorphous oxide thin film is 4 inches of InGaZnO (In: Ga: Zn = 1: 1: 1) using an RF magnetron sputtering apparatus under conditions of room temperature (25 ° C.) and Ar: O ₂ of 30:50. It forms using a target. Then, after forming a resist pattern on the amorphous oxide thin film by photolithography, wet etching is performed with an oxalic acid solution, and the amorphous oxide thin film is patterned to form an amorphous oxide thin film having a predetermined pattern. The amorphous oxide thin film thus obtained is formed on the gate insulating film so as to contact the source electrode and the drain electrode on both sides and straddle the source electrode and the drain electrode. Subsequently, a silicon oxide film having a thickness of 100 nm is formed as a protective film by RF magnetron sputtering so as to cover the whole, and then a resist pattern is formed by photolithography and then dry etching is performed. After annealing at 300 ° C. for 1 hour in the atmosphere, an EL partition layer is formed using an acrylic positive resist to produce a TFT substrate.

  After depositing an EL layer to be white on the TFT substrate, an IZO film was deposited as an electrode, and EL was sealed using a barrier film. Next, a flexible color filter formed on the PEN film is bonded to produce a flexible diagonal 4.7 inch, resolution 85 dpi, 320 × 240 × RGB (QVGA) active matrix drive full color EL display.

DESCRIPTION OF SYMBOLS 1 ... Substrate for flexible devices 2 ... Base material 3 ... Flattening layer 4 ... Adhesion layer 5 ... Die coater 6 ... Coating liquid

Claims (4)

  A planarization layer formed on the substrate and containing polyimide, the surface roughness Ra at a measurement area of 10 μm square on the planarization layer surface is 5 nm or less, and the planarization layer A substrate for a flexible device having a surface roughness Ra of 5 nm or less at a surface measurement region of 1 μm square.   The board | substrate for flexible devices of Claim 1 whose number average molecular weights of the said polyimide are 2,000-1,000,000.   The board | substrate for flexible devices of Claim 1 or 2 whose film thickness of the said planarization layer is 0.2-1000 micrometers.   The manufacturing method of the board | substrate for flexible devices as described in any one of Claims 1-3 including the insulating layer formation process which apply | coats a polyimide resin composition on a base material by a die-coat method, and forms an insulating layer.

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