JP2008159934A - Flexible tft substrate, manufacturing method thereof and flexible display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible TFT substrate in which a desired organic TFT element is formed on a plastic film without causing any trouble and a sufficient numeric aperture is given. <P>SOLUTION: The flexible TFT substrate has the following constituents sequentially formed on the plastic film 20, i.e., an adhesive layer 46; a lower insulating layer 44; TFTs 5, 6 consisting of organic active layers 38a, 38b, source electrodes 36a, 36x, drain electrodes 36b, 36y, a gate insulating layer 34 and gate electrodes 32a, 32b and embedded in the lower insulating layer 44; upper insulating layers 30, 28; and a pixel electrode 26. The drain electrode 36y of the TFT 6 is electrically connected to the pixel electrode 26 through via holes VH provided on the upper insulating layers 30, 28, and the TFTs 5, 6 are disposed on positions of overlapping on the pixel electrode 26. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flexible TFT substrate, a manufacturing method thereof, and a flexible display, and more specifically, a flexible TFT substrate including an organic TFT element on a plastic film, a manufacturing method thereof, and the TFT substrate. The present invention relates to flexible displays such as organic EL displays and liquid crystal displays.

  Display devices such as organic EL (Electroluminescence) displays and liquid crystal displays are rapidly expanding their applications to information equipment. In recent years, a flexible display using a plastic film as a substrate has attracted attention. Such flexible displays can be used not only for ultra-thin and lightweight mobile devices that can be rolled up and stored, but also for large displays.

  However, the plastic film has a low rigidity and a low thermal deformation temperature, and thus is likely to undergo thermal deformation such as warping and expansion / contraction in a manufacturing process involving heat treatment. For this reason, in a manufacturing method in which various elements are formed directly on a plastic film, conditions such as a manufacturing process involving heat treatment are limited, and high-precision alignment becomes difficult, so that an element substrate having desired characteristics is manufactured. It may not be possible.

  In order to avoid such problems, a transfer layer is formed by aligning amorphous silicon TFT elements and color filters with high precision on a heat-resistant and rigid glass substrate without restricting manufacturing conditions. There is a method of manufacturing an element substrate for a liquid crystal display device by transferring and forming the transfer layer on a plastic film (Patent Document 1).

  Further, the flexible display requires a flexible TFT element that can follow the bending, and there is a possibility that sufficient reliability cannot be obtained with an amorphous silicon TFT or a low-temperature polysilicon TFT as a conventional driving transistor. For this reason, organic TFTs that use flexible organic semiconductors that can follow bending as active layers have attracted attention as driving transistors for flexible displays.

  In Patent Document 2, a gate electrode, a gate insulating film, an organic semiconductor layer, and a source / drain electrode are sequentially formed on a plastic substrate or the like, and an organic EL element is formed on an anode connected to the drain electrode. Describes a method for producing an organic EL display.

Patent Document 3 describes that an organic TFT element can be easily formed not only on a glass substrate but also on a plastic substrate by forming a semiconductor layer from a polymer inclusion complex that does not require a high-temperature process. Yes.
JP 2001-356370 A JP 2003-255857 A JP 2003-298067 A

  By the way, the organic semiconductor layer and the organic EL layer have a problem in that their performance deteriorates or eventually becomes nonfunctional in a photolithography and etching process that involves processing such as an organic solvent, water, plasma, electron beam, or heat treatment. .

  In Patent Document 2 described above, after the organic semiconductor layer is formed, it is necessary to pattern the source / drain electrodes and the like, so there is a possibility that performance degradation of the organic semiconductor layer in the photolithography process may become a problem. Thus, the manufacturing method of the flexible TFT substrate provided with the organic TFT using the plastic film as the substrate has not been sufficiently established, and a method of stably forming the desired organic TFT on the plastic film with a high yield. Is anxious.

  Further, in Patent Documents 1 to 3, since the TFT elements are arranged outside the pixel electrode pattern region, there is a limit to increasing the area of the pixel electrode in each pixel, and the entire display screen is limited. There is a problem that the aperture ratio (occupation ratio of the light emitting portion) is not necessarily sufficient.

  The present invention has been created in view of the above-described problems, and a desired organic TFT element can be formed on a plastic film without any problem, and a flexible TFT substrate having a sufficient aperture ratio and An object of the present invention is to provide a manufacturing method and a flexible display using the manufacturing method.

  In order to solve the above-described problems, the present invention relates to a flexible TFT substrate, which is an active matrix type flexible TFT substrate in which a TFT is provided for each pixel, and includes a plastic film and an adhesive formed on the plastic film. A layer, a lower insulating layer formed on the adhesive layer, and a TFT embedded in the lower insulating layer, and in order from the bottom, an organic active layer, a source electrode and a drain electrode, and a gate insulating layer A TFT formed by forming a layer and a gate electrode; an upper insulating layer formed on the TFT; a pixel electrode embedded in the upper insulating layer; and an upper insulating layer. A via hole that reaches the pixel electrode, and the drain electrode of the TFT is electrically connected to the pixel electrode through the via hole. The TFT is characterized in that it is disposed at a position overlapping the pattern area of the pixel electrode.

  The flexible TFT substrate of the present invention has a pixel electrode, a first insulating layer that serves as an upper insulating layer, a TFT, and a second insulating layer that serves as a lower insulating layer on a temporary substrate (such as a glass substrate). After being formed in order, it is obtained by being transferred and formed on a plastic film in an inverted state via an adhesive layer. The TFT is transferred onto a plastic film while being inverted upside down from the structure formed on the temporary substrate, and the organic active layer, the source and drain electrodes, the gate insulating layer, and the gate electrode are formed in order from the bottom. Has been. In addition, a via hole reaching the pixel electrode is provided in a required portion of the upper insulating layer above the TFT, and the drain electrode of the TFT is electrically connected to the pixel electrode through the via hole. Further, the TFT is disposed at a position overlapping the pattern region of the pixel electrode.

  Thus, in the flexible TFT substrate of the present invention, the TFT is disposed under the pixel electrode pattern region via the upper insulating layer, and the TFT drain electrode is connected to the pixel electrode via the via hole provided in the upper insulating layer. It is connected. For this reason, since the arrangement region of the pixel electrode is not limited by the TFT, the pixel electrode can be arranged in the entire region of each pixel portion. Therefore, when the flexible TFT substrate of the present invention is applied to an organic EL display or a liquid crystal display, the aperture ratio (occupation ratio of the light emitting part) can be remarkably increased as compared with the case where the TFT is arranged in the lateral direction of the pixel electrode. become. Thereby, in an organic EL display, a liquid crystal display, etc., high brightness and high definition can be achieved, and display characteristics can be improved.

  A flexible organic EL display is formed by sequentially forming an organic EL layer, a counter electrode, and a sealing layer on the pixel electrode of the flexible TFT substrate of the present invention. In addition, an alignment film is formed on the pixel electrode of the flexible TFT substrate of the present invention, a counter substrate is bonded to the liquid crystal, and a liquid crystal is sealed between them to constitute a flexible liquid crystal display.

  In order to solve the above problems, the present invention relates to a method for manufacturing a flexible TFT substrate, and more particularly to a method for manufacturing an active matrix type flexible TFT substrate in which a TFT is provided for each pixel, and a release layer on a temporary substrate. Forming a pixel electrode above the release layer, forming a first insulating layer on the pixel electrode, and forming a gate on the first insulating layer in order from the bottom. A step of forming the TFT including an electrode, a gate insulating layer, a source electrode and a drain electrode, and an organic active layer, wherein the drain electrode of the TFT is provided in the first insulating layer; Forming the TFT connected to the pixel electrode via the step, forming a second insulating layer on the TFT, and a plastic layer on the second insulating layer via an adhesive layer. The step of adhering a film and the temporary substrate are peeled off from the interface with the release layer, whereby the second insulating layer, the TFT, and the first insulating layer are formed on the plastic film via the adhesive layer. The method includes transferring and forming the pixel electrode and the release layer, and exposing the pixel electrode by removing the release layer.

  By using the manufacturing method of the present invention, the flexible TFT substrate of the above-described invention can be easily manufactured. Further, in the method for manufacturing a flexible TFT substrate of the present invention, a step of using photolithography (a step of forming a gate electrode, a source electrode and a drain electrode, and a via hole) is performed on the temporary substrate before forming the organic active layer. Therefore, the TFT can be formed with high alignment accuracy and the performance of the organic active layer is not deteriorated in the photolithography process. Furthermore, since the organic EL layer can be formed on the pixel electrode by a mask vapor deposition method or an ink jet method without using photolithography, the performance of the organic EL layer is prevented from being deteriorated, and a highly reliable flexible organic EL. A display can be manufactured.

  As described above, according to the present invention, a desired organic TFT element can be formed on a plastic film without causing any problems, and a flexible display having a sufficient aperture ratio can be configured.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
1 to 6 are sectional views showing a method for manufacturing a flexible TFT substrate according to the first embodiment of the present invention, FIG. 7 is a sectional view showing the flexible TFT substrate, and FIG. 8 is a flexible organic substrate according to the first embodiment of the present invention. Sectional drawing which shows the manufacturing method of EL display, FIG. 9 is sectional drawing which similarly shows a flexible organic EL display.

In the manufacturing method of the flexible TFT substrate of this embodiment, as shown in FIG. 1A, first, a glass substrate 10 is prepared as a temporary substrate, and a release layer 22 made of polyimide resin or the like is provided on the glass substrate 10. Form. Thereafter, as shown in FIG. 1B, a base barrier layer 24 made of an inorganic insulating layer such as silicon nitride (SiN _x ) is formed on the release layer 22 by CVD or sputtering. Further, a conductive layer 26a having a thickness of 50 to 300 nm for forming a pixel electrode is formed on the base barrier layer 24 by sputtering.

  Next, as shown in FIG. 1C, a resist pattern (not shown) is formed on the conductive layer 26a, and the conductive layer 26a is etched using the resist pattern as a mask, whereby the pixel electrode 26 is obtained. Thereafter, the resist pattern is removed. The pixel electrode 26 may be formed of a transparent conductive layer such as an ITO (Indium Tin Oxide) layer or an IZO (Indium Zinc Oxide) layer, or a gold (Au) layer, a platinum (Pt) layer, or a silver (Ag) layer. You may form from opaque conductive layers, such as. Alternatively, the pixel electrode 26 may be configured by forming a chromium (Cr) layer / ITO layer in order from the bottom.

In the present embodiment, since the pixel electrode 26 is formed on the glass substrate 10, the process conditions such as the film formation temperature are not limited unlike the case where the pixel electrode 26 is formed on the plastic film. For example, when an ITO layer is used as the pixel electrode 26, a sputtering method having a film forming temperature of about 200 ° C. can be employed. Thus, the pixel electrode 26 (ITO) is formed with low resistance (specific resistance value: 3 × 10 ⁻⁴ Ω · cm or less) electrical characteristics.

  Note that the base barrier layer 24 may be omitted, and the pixel electrode 26 may be formed directly on the release layer 22.

Subsequently, as illustrated in FIG. 1D, an interlayer insulating layer 28 that fills the step of the pixel electrode 26 is formed by applying polyimide resin or the like on the pixel electrode 26 by a spin coating method. Thereby, the step of the pixel electrode 26 is eliminated and the interlayer insulating layer 28 is formed with a flat upper surface. Further, a barrier insulating layer 30 having a gas barrier function of an inorganic insulating layer (such as silicon nitride (SiN _x )) is formed on the interlayer insulating layer 28 by CVD or sputtering. In the present embodiment, the interlayer insulating layer 28 and the barrier insulating layer 30 constitute a first insulating layer.

  Next, as shown in FIG. 2A, a conductive layer made of tantalum (Ta), aluminum (Al), chromium (Cr), IZO or ITO is deposited on the barrier insulating layer 30 by vapor deposition or sputtering. After the formation, the conductive layer is patterned by photolithography and etching. Thereby, a gate electrode 32 a for a switching TFT (Thin Film Transistor) (hereinafter referred to as Sw-TFT) is formed on the barrier insulating layer 30 on the pattern region of the pixel electrode 26. At the same time, a gate electrode 32 b for a driving TFT (hereinafter referred to as Dr-TFT) is formed on the barrier insulating layer 30 on the pattern region of the pixel electrode 26.

Further, as shown in FIG. 2B, a gate insulating layer 34 that covers the upper and side surfaces of the gate electrodes 32a and 32b is formed. As the gate insulating layer 34, a silicon oxide layer (SiO _x ), a tantalum oxide layer (Ta ₂ O ₅ ), an alumina layer (Al ₂ O ₅ ) or the like having a film thickness of about 200 nm is used. Then, after these insulating layers are formed by a CVD method or a sputtering method, the gate insulating layer 34 is obtained by patterning based on photolithography. Alternatively, the gate insulating layer 34 may be formed by an anodic oxidation method. The gate insulating layer 34 may be left on the entire upper surface side of the glass substrate 10 without patterning.

  Next, as shown in FIG. 2C, by processing the portions of the interlayer insulating layer 28 and the barrier insulating layer 30 on the required portions of the pixel electrode 26, a via hole VH having a depth reaching the pixel electrode 26 is formed. To do. In the via hole VH, after a resist pattern (not shown) having an opening is formed on the barrier insulating layer 30, the barrier insulating layer 30 and the interlayer insulating layer 28 are etched by dry etching or the like through the opening. It is formed.

  Next, as shown in FIG. 3A, a chromium (Cr) layer and gold (on the upper surface side of the structure of FIG. 2C (on the barrier insulating layer 30 and the gate insulating layer 34 and in the via hole VH)). After an Au) layer is sequentially formed to form a metal layer, the metal layer is patterned by photolithography and etching. Accordingly, the source electrode 36a and the drain electrode 36b for the Sw-TFT are formed to extend from the upper surface end side to the side surface of the gate insulating layer 34 covering the gate electrode 32a. At the same time, a source electrode 36x and a drain electrode 36y for the Dr-TFT are formed extending from the upper surface end side to the side surface of the gate insulating layer 34 covering the gate electrode 32b. Further, the drain electrode 36y for the Dr-TFT is formed by being electrically connected to the pixel electrode 26 through the via hole VH.

  Next, as shown in FIG. 3B, an organic active layer 38 made of an organic semiconductor having a thickness of about 50 nm is formed on the entire top surface of the structure of FIG. As a material of the organic active layer 38, pentacene, sexithiophene, polythiophene, or the like is preferably used.

Further, as shown in FIG. 3C, a parylene (polyparaxylylene) resin layer 40 is formed on the organic active layer 38 by a vacuum deposition method or the like. Subsequently, as shown in FIG. 4A, an inorganic insulating layer 42 made of a silicon oxide layer (SiO ₂ ) or the like is formed on the parylene resin layer 40.

  Subsequently, as illustrated in FIG. 4B, a resist pattern 15 corresponding to the Sw-TFT gate insulating layer 34 and the Dr-TFT gate insulating layer 34 is formed on the inorganic insulating layer 42. Further, as shown in FIG. 4C, the inorganic insulating layer 42, the parylene resin layer 40, and the organic active layer 38 are etched using the resist pattern 15 as a mask. The resist pattern 15 may be removed by dry etching.

  As a result, the Sw-TFT organic active layer 38a, the cap protective layer 40a made of the parylene resin layer 40, and the inorganic insulating layer 42 are formed on the Sw-TFT source electrode 36a, drain electrode 36b, and gate insulating layer 34. A cap barrier layer 42a is obtained by patterning. At the same time, the Dr-TFT organic active layer 38b, the cap protective layer 40b, and the cap barrier layer 42b are patterned on the source electrode 36x, the drain electrode 36y, and the gate insulating layer 34 for the Dr-TFT.

  At this time, the organic active layers 38a and 38b are covered and protected by the cap barrier layers 42a and 42b (inorganic insulating layers) and the cap protective layers 40a and 40b (parylene resin layers), so that they are wet in the photolithography process. Performance degradation due to processing or plasma is prevented. Note that the resist pattern 15 may be left without being removed.

  Thereby, the Sw-TFT 5 including the gate electrode 32a, the gate insulating layer 34, the source electrode 36a and the drain electrode 36b, and the organic active layer 38a electrically connected to the source electrode 36a and the drain electrode 36b is obtained. In addition, the Dr-TFT 6 including the gate electrode 32b, the gate insulating layer 34, the source electrode 36x and the drain electrode 36y, and the organic active layer 38b electrically connected to the source electrode 36x and the drain electrode 36y is obtained. The drain electrode 36y of the Dr-TFT 6 is electrically connected to the pixel electrode 26 disposed below the Dr-TFT 6 through the via hole VH.

  In this embodiment, since the Sw-TFT 5 and the Dr-TFT 6 are formed on the heat-resistant glass substrate 10, a desired TFT can be obtained with high alignment accuracy, unlike the case where it is directly formed on a plastic film. .

  In the present embodiment, the Sw-TFT 5 and the Dr-TFT 6 are disposed on the pixel electrode 26 at a position overlapping the pattern region of the pixel electrode 26 via the interlayer insulating layer 28 and the barrier insulating layer 30. Therefore, as will be described later, the pixel electrode 26 can be disposed in the entire region of the pixel portion without limiting the region in which the pixel electrode 26 is disposed. (Occupation ratio) can be increased.

  The organic active layers 38a and 38b, the cap protective layers 40a and 40b, and the cap barrier layers 42a and 42b may be formed by patterning by a mask vapor deposition method. The mask vapor deposition method is a method of forming a pattern simultaneously with film formation by moving a shadow mask with high accuracy in a vacuum vapor deposition apparatus. The patterned organic active layer 38a, 38b, cap protective layers 40a and 40b, and cap barrier layers 42a and 42b can be stacked in sequence. For this reason, there is no possibility that the performance of the organic active layers 38a and 38b deteriorates in the photolithography process. Alternatively, the organic active layers 38a and 38b may be patterned by an ink jet method.

Next, as shown in FIG. 5A, a protective insulating layer 44 (second insulating layer) is formed on the Sw-TFT 5 and the Dr-TFT 6 so as to cover them. The protective insulating layer 44 is a laminate of a parylene layer and an inorganic insulating layer such as a silicon oxide layer (SiO _x ), a silicon nitride layer (SiN _x ), or a silicon oxynitride layer (SiON) that can block the entry of water vapor or gas. A film is preferably used and formed by a CVD method or a vacuum deposition method. Or you may form the protective insulating layer 44 from organic resin layers, such as polyimide resins other than parylene, an epoxy resin, an acrylic resin, polyvinyl alcohol, or polyparaxylene.

  After that, as shown in FIG. 5B, the plastic film 20 is disposed on the upper surface of the protective insulating layer 44 in FIG. Further, the adhesive layer 46 is cured by heat treatment, and the plastic film 20 is bonded onto the structure shown in FIG. As the plastic film 20, a polyethersulfone film or a polycarbonate film having a film thickness of 100 to 200 μm is preferably used.

  Note that, when the protective insulating layer 44 is formed by a CVD method or a vacuum evaporation method, a process becomes complicated in order to flatten the steps of the Sw-TFT 5 and the Dr-TFT 6, so that the protective insulating layer 44 has a step on its upper surface. Is often formed. However, since the level difference of the protective insulating layer 44 can be eliminated by being embedded in the adhesive layer 46, the plastic film 20 is bonded with the upper surface of the adhesive layer 46 being flat.

  Subsequently, as shown in FIG. 6A, the roll 17 is fixed to one end of the plastic film 20, and the glass substrate 10 is peeled while rotating the roll 17. At this time, it peels along the interface (A part of Fig.6 (a)) of the glass substrate 10 and the peeling layer 22, and the glass substrate 10 is discarded.

  FIG. 6B shows a state where the glass substrate 10 removed from the structure of FIG. 6A is turned upside down. As shown in FIG. 6B, an adhesive layer 46, a protective insulating layer 44, and cap barrier layers 42a and 42b and cap protective layers 40a and 40b are provided on the plastic film 20 in order from the bottom. Sw-TFT 5 and Dr-TFT 6, barrier insulating layer 30, interlayer insulating layer 28, pixel electrode 26, base barrier layer 24, and release layer 22 are transferred and formed.

Thereafter, as shown in FIG. 7, the base barrier layer 24 is exposed by removing the release layer 22 with oxygen gas plasma or the like. Further, the underlying barrier layer 24 is removed by etching with CF ₄ plasma or the like, thereby exposing the pixel electrode 26.

  As described above, the flexible TFT substrate 1 of the present embodiment is obtained.

  As shown in FIG. 7, in the flexible TFT substrate 1 of this embodiment, an adhesive layer 46 and a protective insulating layer 44 (lower insulating layer) are sequentially formed on the plastic film 20. A Sw-TFT 5 and a Dr-TFT 6 are embedded in the protective insulating layer 44, and the barrier insulating layer 30 is formed thereon.

  The Sw-TFT 5 includes an organic active layer 38a, a source electrode 36a and a drain electrode 36b, a gate insulating layer 34, and a gate electrode 32a formed in this order from the bottom, and a cap protection is provided on the lower surface of the organic active layer 38a. A layer 40a and a cap barrier layer 42a (cap insulating layer) are provided. Similarly, in the Dr-TFT 6, the organic active layer 38b, the source electrode 36x and the drain electrode 36y, the gate insulating layer 34, and the gate electrode 32b are formed in order from the bottom, and the lower surface of the organic active layer 38b is formed. Are provided with a cap protective layer 40b and a cap barrier layer 42b.

  In this embodiment, since the transfer technique described above is employed, the Sw-TFT 5 and the Dr-TFT 6 are arranged in a state where the Sw-TFT 5 and the Dr-TFT 6 formed on the barrier insulating layer 30 are vertically inverted. ing.

  Therefore, in the Sw-TFT 5 and the Dr-TFT 6, the gate electrodes 32 a and 32 b are disposed so as to protrude downward from the lower surface of the barrier insulating layer 30 with the upper surfaces thereof being flush with the upper surface of the protective insulating layer 44. Yes. The lower and side surfaces of the gate electrodes 32a and 32b are covered with the gate insulating layer 34. Furthermore, the source electrodes 36a and 36x and the drain electrodes 36b and 36y extend upward from between the organic active layers 38a and 38b and the gate insulating layer 34 to the sides of the gate electrodes 32a and 32b, respectively.

  Organic active layers 38a and 38b are disposed below the source electrodes 36a and 36x and the drain electrodes 36b and 36y, and the organic active layers 38a and 38b between the source electrodes 36a and 36x and the drain electrodes 36b and 36y, The portion 38b is a TFT channel portion that contacts the gate insulating layer 34.

  Further, an interlayer insulating layer 28 is formed on the barrier insulating layer 30, and the pixel electrode 26 is formed to be buried in the interlayer insulating layer 28 with its upper surface exposed. The upper surfaces of the pixel electrode 26 and the interlayer insulating layer 28 are flattened to be the same surface. In the present embodiment, the interlayer insulating layer 28 and the barrier insulating layer 30 constitute an upper insulating layer. In addition, a via hole VH is provided in a portion of the interlayer insulating layer 28 and the barrier insulating layer 30 below a required portion of the pixel electrode 26. The drain electrode 36y of the Dr-TFT 6 is electrically connected to the pixel electrode 26 through the via hole VH.

  As described above, in the flexible TFT substrate 1 of the present embodiment, the Sw-TFT 5 and the Dr-TFT 6 are arranged on the lower side of the pattern region of the pixel electrode 26 so as to overlap the pixel electrode 26. The drain electrode 36 y of the Dr-TFT 6 is electrically connected to the pixel electrode 26 through a via hole VH provided in the interlayer insulating layer 28 and the barrier insulating layer 30.

  By adopting such a configuration, the pixel electrode 26 can be disposed in the entire region of each pixel unit without limiting the region in which the pixel electrode 26 is disposed by the Sw-TFT 5 and the Dr-TFT 6. The area of the pixel electrode 26 can be increased by arranging the pixel electrode 26 in the entire region.

  Further, since the organic active layers 38a and 38b are disposed between the barrier insulating layer 30 and the protective insulating layer 44, water vapor from outside air or moisture in the plastic film 20 can enter the organic active layers 38a and 38b. A highly reliable flexible TFT substrate is formed.

  Next, a method for manufacturing an organic EL display using the flexible TFT substrate 1 of the present embodiment will be described. As shown in FIG. 8, first, a hole transport layer 52 having a film thickness of, for example, 30 nm is selectively formed on the pixel electrode 26 exposed on the upper surface side of the flexible TFT substrate 1 of FIG. . As the hole transport layer 52, α-NPD which is an aromatic tertiary amine derivative is preferably used.

  Further, as shown in FIG. 8, a low molecular light emitting layer 54 having a thickness of, for example, 70 nm is selectively formed on the hole transport layer 52 by a mask vapor deposition method. In the present embodiment, an example in which the light emitting layer 54 of three primary colors is formed to form a full color is illustrated, so that the three primary colors (red (R), green (G), and blue (B) will be described later with reference to FIG. ), A red light emitting layer, a green light emitting layer, and a blue light emitting layer are formed on the hole transport layer 52 of each pixel portion. As the low molecular light emitting layer 54, a host material mixed with a doping material is used, and the doping material (molecule) emits light. Examples of the host material include Alq3 and a distyrylarylene derivative (DPVBi), and examples of the doping material include green-emitting coumarin 6 and red-emitting DCJTB.

  Subsequently, as shown in FIG. 8, an electron transport layer 56 is formed on the light emitting layer 54 by mask vapor deposition. As the electron transport layer 56, quinolinol aluminum complex (Alq3) or the like is preferably used.

  Alternatively, the hole transport layer 52, the light emitting layer 54, and the electron transport layer 56 may be formed by an inkjet method.

  Thereby, the organic EL layer 50 comprised by the positive hole transport layer 52, the light emitting layer 54, and the electron carrying layer 56 is obtained.

  Note that only one of the hole transport layer 52 and the electron transport layer 56 may be formed, or both the hole transport layer 52 and the electron transport layer 56 may be omitted.

  Further, as shown in FIG. 8, a counter electrode 58 facing the pixel electrode 26 is formed on the electron transport layer 56 by mask vapor deposition. The counter electrode 58 is formed as a common electrode. As the counter electrode 58, a transparent electrode may be used, or an opaque electrode such as a lithium fluoride / aluminum (LiF / Al) laminated film may be used. When the counter electrode 58 is formed of a transparent electrode, an electrode in which a BCP layer, a BCP layer containing CS, or an ultrathin Al layer is formed below the ITO layer is preferably used.

In the present embodiment, since a form in which light is emitted is shown in the upper side of FIG. 8, the pixel electrode 26 is formed from an opaque electrode, and the counter electrode 58 is formed from a transparent electrode. On the other hand, when light is emitted to the lower side of FIG. 8, the pixel electrode 26 is formed from a transparent electrode, and the counter electrode 58 is formed from an opaque electrode.
Thereby, the organic EL element 2 comprised by the pixel electrode 26, the organic EL layer 50, and the counter electrode 58 is obtained.

  As described above, in this embodiment, in the step of forming the organic active layers 38a and 38b, the organic active layers 38a and 38b are protected by the cap protection layers 40a and 40b and the cap barrier layers 42a and 42b. Even if is used, there is no possibility that the performance of the organic active layers 38a and 38b is deteriorated. Further, since the organic EL layer 50 is formed without using photolithography, the performance of the organic EL layer 50 is not deteriorated.

Thereafter, as shown in FIG. 9, a sealing layer 59 is formed on the organic EL element 2 to cover it. As the sealing layer 59, a silicon oxide layer (SiO _x ), a silicon nitride layer (SiN _x ), or the like is used. For example, the sealing layer 59 is formed by low temperature CVD at a film forming temperature of about 100 ° C. Or it is good also as the sealing layer 59 by sticking the resin film in which the moisture-proof layer was formed.

  Thus, the flexible organic EL display 3 according to the first embodiment of the present invention is completed.

  In FIG. 10, the three primary color pixel portions (red pixel portion (R), green pixel portion (G), and blue pixel portion (B)) of the flexible organic EL display 3 of the first embodiment are depicted. As shown in FIG. 10, in each of the three primary color pixel portions (R), (G), and (B), the above-described Sw-TFT 5 and the drain electrode 36y are connected to the pixel electrode 26 via the via hole VH. Each of the TFTs 6 is disposed.

  The organic EL layer 50 described above is formed on the pixel electrode 26 of each pixel portion (R), (G), (B), and each pixel portion (R), (G), (B ), A red light emitting layer 54R, a green light emitting layer 54G, and a blue light emitting layer 54B are respectively provided. These light emitting layers 54R, 54G, and 54B are obtained by being sequentially formed by a mask vapor deposition method.

  Alternatively, the red light emitting layer 54R, the green light emitting layer 54G, and the blue light emitting layer 54B may be separately applied by an inkjet method. A pixel portion (sub-pixel) of three primary colors constitutes a pixel as a display unit. Since other elements are the same as those in FIG. 9, the same reference numerals are given and description thereof is omitted.

  FIG. 11 is a diagram showing an equivalent circuit of the pixel portion of the flexible organic EL display according to the first embodiment of the present invention, and FIG. 12 is a plan view showing an example of the pixel portion of the flexible display according to the first embodiment of the present invention.

  The equivalent circuit of FIG. 11 will be described with reference to the plan view of FIG. 12 as appropriate. The counter electrode 58 (cathode) of the organic EL element 2 is connected to the ground (GND) 66 and the pixel electrode 26 (anode) of the organic EL element 2 is connected. ) Is connected to the drain electrode 36y of the Dr-TFT 6 through the via hole VH. The source electrode 36 x of the Dr-TFT 6 is connected to a power supply (Vdd) line 60.

  Further, a storage capacitor Cs is formed between the gate electrode 32 b of the Dr-TFT 6 and the power supply (Vdd) line 60. Further, the drain electrode 36 b of the Sw-TFT 5 is connected to the gate electrode 32 b of the Dr-TFT 6, and the source electrode 36 a of the Sw-TFT 5 is connected to the data line 62. Further, the gate electrode 32 a of the Sw-TFT 5 is connected to the scanning line 64.

  The equivalent circuit of FIG. 11 operates as follows. First, when the potential of the scanning line 64 is selected and a writing potential is applied to the scanning line 64, the Sw-TFT 5 is turned on to charge or discharge the storage capacitor Cs, and the gate potential of the Dr-TFT 6 becomes the writing potential. Next, when the potential of the scanning line 64 is set to a non-selected state, the scanning line 64 and the Dr-TFT 6 are electrically disconnected, but the gate potential of the Dr-TFT 6 is stably held by the storage capacitor Cs.

  Then, the current flowing through the Dr-TFT 6 and the organic EL element 2 has a value corresponding to the gate-source voltage of the Dr-TFT 6, and the organic EL element 2 continues to emit light with the luminance corresponding to the current value.

  An active matrix organic EL display can be configured by arranging a plurality of pixels having such a configuration in a matrix and repeating writing through the data lines 62 while sequentially selecting the scanning lines 64. In this manner, light of a predetermined color is emitted to the outside from the light emitting layers 54R, 54G, and 54B of the pixel portions (R), (G), and (B) to obtain a color image (FIG. 10). Arrow direction).

  In the present embodiment, as shown in FIG. 12, pixel electrodes 26 (regions surrounded by thick lines) are arranged on the entire pixel portions defined by the scanning lines 64, the data lines 62, and the power supply (Vdd) lines 60, respectively. In addition, the Sw-TFT 5 and the Dr-TFT 6 are arranged in a state of being overlapped under the pattern region of the pixel electrode 26.

  In particular, when light is emitted to the upper side of the display as shown in FIG. 10, since the light amount is not affected at all by the arrangement of the Sw-TFT 5 and the Dr-TFT 6, the aperture ratio (occupation ratio of the light emitting part) is remarkably improved. be able to. As a result, it is possible to increase the brightness and definition of the flexible organic EL display.

  FIG. 13 shows a plan view of a pixel portion of a flexible organic EL display of a comparative example. As shown in FIG. 13, in the flexible organic EL display of the comparative example, the Sw-TFT 5 and the Dr-TFT 6 are arranged on the peripheral side of the pixel portion, and the pixel electrode 26 (the region surrounded by the thick line) is the Sw-TFT 5 and the Dr. -The TFTs 6 are arranged side by side so as not to overlap. Therefore, unlike the present embodiment, the non-light emitting portion is considerably present in each pixel portion, so that the aperture ratio of the display is lowered.

  In the present embodiment, even when light is emitted downward in FIG. 10, a sufficient aperture ratio can be obtained as compared with the comparative example, although part of the light is blocked by the opaque portions of the Sw-TFT 5 and the Dr-TFT 6.

  The pixel portion of the flexible display in FIG. 12 is an example laid out based on the technical idea of the flexible TFT substrate of the present invention, and it goes without saying that various layouts can be adopted.

  Further, a white light emitting layer is formed as the light emitting layer 54, and between the pixel electrode 26 and the Sw-TFT 5 and the Dr-TFT 6 (between the interlayer insulating layer 28 and the barrier insulating layer 30) as in the second embodiment described later. A color filter layer may be formed to achieve full color. In this case, the via hole VH is formed in the interlayer insulating layer 28, the color filter layer, and the barrier insulating layer 30. Further, in this embodiment, since it is necessary to design so that light is emitted to the lower side of FIG. 10 (opposite to the direction of the arrow), the pixel electrode 26 is formed of a transparent conductive layer, and the counter electrode 58 is It is formed from an opaque conductive layer.

(Second Embodiment)
14-17 is sectional drawing which shows the manufacturing method of the flexible liquid crystal display of 2nd Embodiment of this invention, FIG. 18 is sectional drawing which similarly shows a flexible liquid crystal display. The second embodiment exemplifies a mode in which the flexible TFT substrate according to the embodiment of the present invention is applied to a liquid crystal display. In the second embodiment, detailed description of the same steps as those in the first embodiment is omitted. Moreover, the same code | symbol is attached | subjected to the same element and the description is abbreviate | omitted.

  As shown in FIG. 14A, first, a peeling layer 22, a base barrier layer 24, and a pixel electrode 26 are formed on a glass substrate 10, and the same structure as in FIG. 1C of the first embodiment. Get. Next, as shown in FIG. 14B, after forming an interlayer insulating layer 28 that covers the pixel electrode 26, a color filter layer 29 is formed on the interlayer insulating layer 28 corresponding to the pixel electrode 26.

  In the present embodiment, an example in which the color filter layer 29 is full-colored is illustrated. FIG. 14B shows only one pixel portion, but the pixel electrodes 26 of the three primary color pixel portions (R), (G), and (B) as shown in FIG. 10 of the first embodiment. A red (R) color filter layer, a green (G) color filter layer, and a blue (B) color filter layer are respectively formed on the substrate.

  A pixel portion (sub-pixel) of three primary colors constitutes a pixel as a display unit. Each of the three primary color filter layers 29 is formed by sequentially patterning, for example, a pigment dispersion type photosensitive coating film by photolithography. Further, the barrier insulating layer 30 is formed on the color filter layer 29.

  The color filter layer 29 may be omitted, and a field color sequential drive type liquid crystal display that performs full color display by switching the three primary colors of the backlight in a time-division manner may be used.

  Next, as shown in FIG. 14C, a TFT gate electrode 32 and a gate insulating layer 34 covering the same are formed on the barrier insulating layer 30 by the same method as in the first embodiment. Further, as shown in FIG. 14D, via holes VH are formed in the portions of the interlayer insulating layer 28, the color filter layer 29, and the barrier insulating layer 30 on the required portions of the pixel electrode 26 by photolithography and etching.

  Subsequently, as shown in FIG. 15A, the source electrode 36a and the drain electrode 36b for TFT are formed from the upper surface end side to the side surface of the gate insulating layer 34 by the same method as in the first embodiment. The drain electrode 36b is electrically connected to the pixel electrode 26 through the via hole VH. Further, the organic active layer 38, the cap protection layer 40, and the cap barrier layer 42 are formed on the portion corresponding to the gate electrode 32 by the same method as in the first embodiment.

  Thereby, as in the first embodiment, the switching TFT 7 including the gate electrode 32, the gate insulating layer 34, the source electrode 36a and the drain electrode 36b, and the organic active layer 38 is formed. In the second embodiment, since a liquid crystal display is configured, one TFT 7 is provided in each pixel portion. Further, a protective insulating layer 44 in which the TFT 7 is embedded is formed.

  Next, as shown in FIG. 15B, the plastic film 20 is bonded onto the protective insulating layer 44 via the adhesive layer 46 by the same method as in the first embodiment. Further, as shown in FIG. 16A, similarly to the first embodiment, the glass substrate 10 is peeled off from the interface between the glass substrate 10 and the peeling layer 22 and discarded. FIG. 16A shows a state in which the structure in which the glass substrate 10 is discarded is turned upside down.

  Subsequently, as shown in FIG. 16B, the pixel electrode 26 is exposed by removing the peeling layer 22 and the underlying barrier layer 24 by the same method as in the first embodiment. Further, as shown in FIG. 17, an alignment film 25 for aligning the liquid crystal is formed on the pixel electrode 26. Thereby, a plexable TFT substrate 1a for a liquid crystal display is obtained.

  As shown in FIG. 17, in the flexible TFT substrate 1a for a liquid crystal display, a plastic film 20 is used as a substrate, and an adhesive layer 46 and a protective insulating layer 44 are sequentially formed thereon. A TFT 7 having the same configuration as that of the first embodiment is embedded in the protective insulating layer 44.

  Further, a barrier insulating layer 30, a color filter layer 29, an interlayer insulating layer 28, and a pixel electrode 26 are sequentially provided on the TFT 7. The drain electrode 36 b of the TFT 7 is electrically connected to the pixel electrode 26 through a via hole VH provided in the barrier insulating layer 30, the color filter layer 29 and the interlayer insulating layer 28. An alignment film 25 is provided on the pixel electrode 26.

  As described above, also in the flexible TFT substrate 1a for the liquid crystal display, the pixel electrode 26 is arranged in the entire region of each pixel portion and the TFT 7 is overlapped with the pixel electrode 26 as in FIG. 12 of the first embodiment. Therefore, a high aperture ratio can be obtained.

  Subsequently, as shown in FIG. 18, a counter substrate 1b arranged to face the flexible TFT substrate 1a is prepared. The counter substrate 1b is basically composed of a plastic film 20a, a common electrode 26a made of ITO or the like formed thereon, and an alignment film 25a formed thereon.

  Then, the flexible TFT substrate 1a and the counter substrate 1b are bonded to each other with a sealant (not shown) provided in the periphery in a state where a predetermined interval is secured by a spacer, and the flexible TFT substrate 1a and the counter substrate 1b are further bonded. The liquid crystal 23 is sealed in the gap.

  Thus, the flexible liquid crystal display 4 of the second embodiment is completed.

  In the flexible liquid crystal display 4 according to the second embodiment, since the TFT 7 is arranged so as to overlap below the pattern region of the pixel electrode 26 as in the first embodiment, the pixel electrode 26 is provided over the entire pixel portion. Can be placed. Therefore, since the aperture ratio (occupation ratio of the light transmission portion) of the flexible liquid crystal display can be improved, high luminance and high definition can be achieved, and display characteristics can be improved.

  In addition, although the example which applies the flexible TFT substrate of this embodiment to an organic EL display or a liquid crystal display was demonstrated, it can apply to various displays, such as electronic paper using an electrophoresis system.

1A to 1D are sectional views (No. 1) showing a method for manufacturing a flexible TFT substrate according to a first embodiment of the present invention. 2A to 2C are sectional views (No. 2) showing the method for manufacturing the flexible TFT substrate according to the first embodiment of the present invention. 3A to 3C are cross-sectional views (part 3) illustrating the method for manufacturing the flexible TFT substrate according to the first embodiment of the present invention. 4A to 4C are cross-sectional views (part 4) showing the method for manufacturing the flexible TFT substrate of the first embodiment of the present invention. 5A and 5B are sectional views (No. 5) showing the method for manufacturing the flexible TFT substrate of the first embodiment of the present invention. 6A and 6B are cross-sectional views (No. 6) showing the method for manufacturing the flexible TFT substrate of the first embodiment of the present invention. FIG. 7 is a sectional view showing the flexible TFT substrate according to the first embodiment of the present invention. FIG. 8 is a cross-sectional view showing a state in which an organic EL element is formed on the flexible TFT substrate of the first embodiment of the present invention. FIG. 9 is a cross-sectional view showing the flexible organic EL display according to the first embodiment of the present invention. FIG. 10 is a cross-sectional view showing a red pixel portion (R), a green pixel portion (G), and a blue pixel portion (B) of the flexible organic EL display according to the first embodiment of the present invention. FIG. 11 is a diagram showing an equivalent circuit of one pixel portion of the flexible organic EL display according to the first embodiment of the invention. FIG. 12 is a plan view showing an example of the layout of the pixel portion in the flexible organic EL display according to the first embodiment of the invention. FIG. 13 is a plan view showing a layout of the pixel portion in the flexible organic EL display of the comparative example. 14A to 14D are sectional views (No. 1) showing the method for manufacturing the flexible liquid crystal display according to the second embodiment of the present invention. 15A and 15B are sectional views (No. 2) showing the method for manufacturing the flexible liquid crystal display according to the second embodiment of the present invention. 16A and 16B are sectional views (No. 3) showing the method for manufacturing the flexible liquid crystal display according to the second embodiment of the present invention. FIG. 17: is sectional drawing (the 4) which shows the manufacturing method of the flexible liquid crystal display of 2nd Embodiment of this invention. FIG. 18 is a sectional view showing a flexible liquid crystal display according to the second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flexible TFT substrate (for organic EL display), 1a ... Flexible TFT substrate (for liquid crystal display), 1b ... Opposite substrate, 2 ... Organic EL element, 3 ... Flexible organic EL display, 4 ... Flexible liquid crystal display, 5 ... Sw -TFT, 6 ... Dr-TFT, 7 ... TFT, 10 ... Glass substrate, 15 ... Resist pattern, 17 ... Roll, 20, 20a ... Plastic film, 22 ... Release layer, 23 ... Liquid crystal, 24 ... Underlying barrier layer, 25 , 25a ... alignment film, 26 ... pixel electrode, 26a ... common electrode, 28 ... interlayer insulating layer, 29 ... color filter layer, 30 ... barrier insulating layer, 32a, 32b ... gate electrode, 34 ... gate insulating layer, 36a, 36x ... Source electrode, 36b, 36y ... Drain electrode, 38a, 38b ... Organic active layer, 40a, 40b Cap protective layer (Parylene resin layer), 42a, 42b ... Cap barrier layer (inorganic insulating layer), 44 ... Protective insulating layer, 46 ... Adhesive layer, 50 ... Organic EL layer, 52 ... Hole transport layer, 54 ... Light emitting layer 56 ... Electron transport layer, VH ... Via hole.

Claims (17)

An active matrix flexible TFT substrate in which a TFT is provided for each pixel,
Plastic film,
An adhesive layer formed on the plastic film;
A lower insulating layer formed on the adhesive layer;
The TFT embedded in the lower insulating layer, the TFT comprising an organic active layer, a source electrode and a drain electrode, a gate insulating layer, and a gate electrode in order from the bottom;
An upper insulating layer formed on the TFT;
A pixel electrode embedded in the upper insulating layer;
A via hole provided in the upper insulating layer and reaching the pixel electrode;
The flexible TFT substrate, wherein the drain electrode of the TFT is electrically connected to the pixel electrode through the via hole, and the TFT is disposed at a position overlapping the pattern region of the pixel electrode . The gate electrode of the TFT is disposed on the lower surface of the upper insulating layer with its upper surface flush with the upper surface of the lower insulating layer, and the gate insulating layer covers the lower surface and side surfaces of the gate electrode. And
2. The flexible TFT according to claim 1, wherein the source electrode and the drain electrode respectively extend upward from between the organic active layer and the gate insulating layer to a side of the gate electrode. substrate.   The flexible TFT substrate according to claim 1, wherein the pixel electrode is disposed in an entire area of the pixel.   2. The flexible TFT substrate according to claim 1, wherein the upper surfaces of the pixel electrode and the upper insulating layer are flattened to be the same surface. The lower insulating layer is a protective layer made of an inorganic insulating layer or an organic insulating layer,
The upper insulating layer is composed of a barrier insulating layer made of an inorganic insulating layer and an interlayer insulating layer made of an organic insulating layer formed on the barrier insulating layer,
The flexible TFT substrate according to claim 4, wherein the pixel electrode is embedded in the interlayer insulating layer.   The flexible TFT substrate according to claim 1, wherein a cap insulating layer for protecting the organic active layer is provided on a lower surface of the organic active layer of the TFT. A flexible TFT substrate according to any one of claims 1 to 6,
An organic EL layer formed on the pixel electrode of the flexible TFT substrate;
A counter electrode formed on the organic EL layer;
A flexible display comprising: a sealing layer covering the counter electrode.   The TFT includes a switching TFT and a driving TFT connected to the switching TFT, and the drain electrode of the driving TFT is connected to the pixel electrode through the via hole. The flexible display according to claim 7.   The pixel is defined by a red pixel portion, a green pixel portion, and a blue pixel portion, and the organic EL layer is formed in a red (R) light emitting layer formed in the red pixel portion and the green pixel portion. The flexible display according to claim 7, further comprising a green (G) light emitting layer and a blue (B) light emitting layer formed in the blue pixel portion. The organic EL layer is
A light emitting layer;
It is constituted by at least one of a hole transport layer formed between the pixel electrode and the light-emitting layer and an electron transport layer formed between the light-emitting layer and the counter electrode. The flexible display according to claim 7. A flexible TFT substrate having a structure in which a first alignment film is provided on the pixel electrode of the flexible TFT substrate according to any one of claims 1 to 6,
A counter substrate, which is disposed by being bonded to the flexible TFT substrate at a predetermined interval, and includes a common electrode and a second alignment film on a plastic film;
A flexible display comprising: a liquid crystal sealed between the flexible TFT substrate and the counter substrate.   12. The flexible TFT substrate according to claim 11, wherein a color filter layer is provided between the pixel electrode and the TFT, and the via hole is provided in the upper insulating layer and the color filter layer. The flexible display as described. An active matrix flexible TFT substrate manufacturing method in which a TFT is provided for each pixel,
Forming a release layer on the temporary substrate;
Forming a pixel electrode above the release layer;
Forming a first insulating layer on the pixel electrode;
Forming the TFT composed of a gate electrode, a gate insulating layer, a source electrode and a drain electrode, and an organic active layer on the first insulating layer in order from the bottom; Forming the TFT in which the drain electrode is connected to the pixel electrode through a via hole provided in the first insulating layer;
Forming a second insulating layer on the TFT;
Adhering a plastic film on the second insulating layer via an adhesive layer;
By peeling the temporary substrate from the interface with the peeling layer, the second insulating layer, the TFT, the first insulating layer, the pixel electrode, and the peeling are formed on the plastic film via the adhesive layer. A step of transferring and forming the layer;
And a step of exposing the pixel electrode by removing the release layer. The step of forming the TFT comprises:
Forming the gate electrode on the first insulating layer;
Forming the gate insulating layer covering the gate electrode;
Forming the via hole reaching the pixel electrode in a required portion of the first insulating layer;
Forming a drain electrode connected to the pixel electrode via the source electrode and the via hole on the gate insulating layer covering the gate electrode;
The method according to claim 13, further comprising: forming the organic active layer on the source electrode and the drain electrode. The step of forming the first insulating layer includes:
Forming an interlayer insulating layer on the pixel electrode to fill the step of the pixel electrode;
The method for manufacturing a flexible TFT substrate according to claim 13, further comprising a step of forming a barrier insulating layer on the interlayer insulating layer. After the step of exposing the pixel electrode,
15. The flexible TFT substrate according to claim 13, wherein a flexible organic EL display is formed by sequentially forming an organic EL layer, a counter electrode, and a sealing layer on the pixel electrode. Method. After the step of exposing the pixel electrode,
The method for manufacturing a flexible TFT substrate according to claim 13 or 14, wherein a flexible TFT substrate for a liquid crystal display is formed by forming an alignment film on the pixel electrode.

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