CN110045535B

CN110045535B - Liquid crystal display device and method for manufacturing the same

Info

Publication number: CN110045535B
Application number: CN201910037539.7A
Authority: CN
Inventors: 山口阳平; 铃村功
Original assignee: Japan Display Inc
Current assignee: Japan Display Inc
Priority date: 2018-01-17
Filing date: 2019-01-15
Publication date: 2022-09-16
Anticipated expiration: 2039-01-15
Also published as: JP2019124830A; CN110045535A

Abstract

The present invention relates to a liquid crystal display device and a method of manufacturing the same. The subject of the invention is to realize a flexible liquid crystal display device. The solution of the present invention is a liquid crystal display device in which a liquid crystal (300) is sandwiched between a display region in which a plurality of pixels having TFTs are formed on a TFT wiring layer (60) including an inorganic insulating film and a counter substrate (200) formed of a resin, wherein a lower polarizing plate (401) is bonded to the TFT wiring layer (60), and an upper polarizing plate (402) is bonded to the counter substrate (200) while sandwiching the liquid crystal (300).

Description

Liquid crystal display device and method for manufacturing the same

Technical Field

The present invention relates to a display device, and more particularly, to a flexible liquid crystal display device.

Background

In a liquid crystal display device, pixels having pixel electrodes, Thin Film Transistors (TFTs), and the like are formed in a matrix, and an image is formed by controlling the transmittance of liquid crystal for each pixel. Liquid crystal display devices are lightweight and capable of displaying images with high definition, and their use is widespread in various fields. In recent years, there is also a field in which a flexible bending of a display device is required in a liquid crystal display device.

Patent document 1 describes the following configuration: in order to realize a flexible liquid crystal display device, TFTs are formed on glass and transferred onto a transparent resin substrate, thereby realizing a flexible liquid crystal display device.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2015-102683

Disclosure of Invention

Problems to be solved by the invention

In a liquid crystal display device, a TFT is used as a switching transistor in a pixel, but when a TFT is formed using polycrystalline silicon (poly-Si), annealing at 400 ℃ or higher is required. When a TFT is formed using an oxide semiconductor, the TFT can be formed by annealing at about 300 ℃. Even if the manufacturing apparatus is set to such a temperature, it is locally higher than 350 ℃.

In order to realize a flexible display device, it is necessary to form a TFT substrate using a resin such as polyimide. There are also various materials for polyimide, and the heat-resistant temperature of transparent polyimide is about 350 ℃. Therefore, a TFT cannot be formed using polycrystalline silicon on transparent polyimide, and a TFT using an oxide semiconductor having high reliability is also difficult to realize.

The invention aims to realize a flexible display device capable of forming a TFT by a high-temperature process.

Means for solving the problems

The present invention has been made to overcome the above problems, and the main specific means are as follows.

(1) A liquid crystal display device in which a liquid crystal is sandwiched between a display region and a counter substrate formed of a resin, wherein a plurality of pixels having TFTs are formed in the display region on an inorganic insulating film, wherein a lower polarizing plate is bonded to the inorganic insulating film.

(2) A method for manufacturing a liquid crystal display device, comprising forming a polyimide on a first glass substrate, forming an inorganic insulating film comprising a plurality of layers on the polyimide, forming a layer containing a TFT on the inorganic insulating film, disposing a counter substrate formed of a transparent resin formed on a second glass substrate so as to face the layer containing the TFT and sandwiching a liquid crystal therebetween, removing the first glass substrate and the polyimide, attaching a lower polarizing plate to the inorganic insulating film, and removing the second glass substrate.

(3) A method for manufacturing a liquid crystal display device, comprising forming an amorphous silicon (a-Si) film on a first glass substrate, forming an inorganic insulating film including a plurality of layers on the a-Si film, forming a layer including a TFT on the inorganic insulating film, disposing a counter substrate made of a transparent resin formed on a second glass substrate so as to face the layer including the TFT and sandwiching a liquid crystal therebetween, removing the first glass substrate, attaching a lower polarizer to the inorganic insulating film or the a-Si film, and removing the second glass substrate.

Drawings

FIG. 1 is a plan view of a liquid crystal display device.

FIG. 2 is a sectional view taken along line A-A of FIG. 1.

FIG. 3 is a plan view of a pixel portion of a liquid crystal display device.

Fig. 4 is a cross-sectional view of a pixel portion of a liquid crystal display device.

FIG. 5 is a plan view of the mother substrate.

Fig. 6 is a cross-sectional view of a colored polyimide formed on a first glass substrate.

FIG. 7 is a cross-sectional view of a TFT wiring layer formed on a colored polyimide.

FIG. 8 is a cross-sectional view showing a state after formation of an alignment film.

FIG. 9 is a cross-sectional view showing a liquid crystal dropped on an alignment film.

FIG. 10 is a cross-sectional view showing a state where a counter substrate with a second glass substrate is bonded.

FIG. 11 is a cross-sectional view of FIG. 10 in a state of being turned upside down.

FIG. 12 is a cross-sectional view showing a state where the first glass substrate is removed.

FIG. 13 is a cross-sectional view showing a state where colored polyimide was removed by plasma ashing.

Fig. 14 is a cross-sectional view showing an example of the plasma ashing process.

FIG. 15 is a cross-sectional view showing another example of the plasma ashing step.

FIG. 16 is a cross-sectional view showing a state where colored polyimide is removed.

FIG. 17 is a cross-sectional view showing a state where a lower polarizing plate is attached to a TFT wiring layer.

FIG. 18 is a sectional view of FIG. 17 in a state where the upper part is turned upside down.

FIG. 19 is a cross-sectional view showing a state where the second glass substrate is removed.

Fig. 20 is a cross-sectional view showing a state where the upper polarizing plate is attached to the counter substrate.

FIG. 21 is a cross-sectional view showing a state where an a-Si film is formed on a first glass substrate in example 2.

FIG. 22 is a cross-sectional view showing a state where a TFT wiring layer is formed on an a-Si film.

FIG. 23 is a cross-sectional view showing a state where the first glass substrate and the a-Si film are removed.

FIG. 24 is a plan view showing a liquid crystal display device of example 3.

Fig. 25 is a cross-sectional view of the terminal region of fig. 24 after being bent.

FIG. 26 is a plan view showing a first embodiment of example 3.

Fig. 27 is a cross-sectional view of the terminal region shown in fig. 26 after being bent.

FIG. 28 is a plan view showing a second embodiment of example 3.

FIG. 29 is a sectional view showing an intermediate step of the second embodiment of example 3.

Fig. 30 is a cross-sectional view of the terminal region of fig. 28 after being bent.

FIG. 31 is a plan view showing a third embodiment of example 3.

Fig. 32 is a detailed cross-sectional view of the terminal area of fig. 31.

Fig. 33 is a cross-sectional view showing a state in which the terminal region in fig. 31 is folded.

FIG. 34 is a sectional view showing a fourth embodiment of example 3.

FIG. 35 is a plan view of example 4.

FIG. 36 is a sectional view taken along line B-B of FIG. 35.

FIG. 37 is a rear view of the preferred embodiment 4.

Description of the reference numerals

10 … liquid crystal cell, 11 … scan line, 12 … video signal line, 13 … pixel, 15 … lead line, 16 … insulating layer, 30 … display region, 40 … terminal region, 41 … driver IC,

42 … bump, 45 … terminal wiring, 46 … anisotropic conductive film, 50 … sealing material,

60 … TFT wiring layer, 70 … protective resin, 90 … glass substrate, 95 … a-Si, 100 … colored polyimide, 101 … first base film, 102 … second base film, 103 … semiconductor layer, 104 … gate insulating film, 105 … gate electrode, 106 … interlayer insulating film, 107 … contact electrode, 108 … inorganic passivation film, 109 … organic passivation film, 110 … common electrode, 111 … capacitor insulating film, 112 … pixel electrode, 113 … orientation film, 130 … via hole, 131 … via hole, 132 … via hole, 200 … opposing substrate, 201 … color filter, 202 … black matrix, 100, … colored polyimide, and the like,

203 … overcoat film, 204 … orientation film, 200 … counter substrate, 210 … upper glass substrate, 220 … color filter layer, 300 … liquid crystal layer, 301 … liquid crystal molecules, 401 … lower polarizer sheet, 402 … upper polarizer sheet, 500 … flexible wiring substrate, 600 … mother substrate, 700 … plasma, 701 … lower electrode, 702 … upper electrode, 710 … clamp, 711 … motor, 720 … mask, 4021 … adhesive material, 4022 … adhesive material, AL … orientation direction, D … drain electrode, S … source electrode

Detailed Description

The present invention will be described in detail below with reference to examples.

[ example 1]

Fig. 1 is a top view of a liquid crystal display device to which the present invention is applied. Fig. 1 shows an example of a liquid crystal display device used in a mobile phone, a tablet personal computer, or the like. In fig. 1, a TFT wiring layer 60 in which pixels including TFTs, pixel electrodes, and the like are arranged in a matrix, and a counter substrate 200 on which a black matrix or the like is formed are bonded via a sealant 50, and liquid crystal is sandwiched between the TFT wiring layer 60 and the counter substrate 200.

The counter substrate 200 is made of a transparent resin such as polyimide. The upper polarizing plate 402 overlaps the opposite substrate 200. The present invention is characterized in that a so-called TFT substrate does not exist, and the TFT wiring layer 60 is directly disposed on the lower polarizer 401. Here, the TFT wiring layer 60 is a concept including various insulating films typified by a base film, TFTs, wirings, an organic passivation film, an alignment film, and the like.

In the TFT wiring layer 60 in the display area 30, the scanning lines 11 extend in the lateral direction (x direction) and are arranged in the longitudinal direction (y direction). In addition, the video signal lines 12 extend in the longitudinal direction and are arranged in the transverse direction. Pixels 13 are formed in regions surrounded by the scanning lines 11 and the video signal lines 12.

The TFT wiring layer 60 extends from the display region 30 to the terminal region 40. Since the TFT wiring layer 60 is a thin layer and is flexible but mechanically weak, the lower polarizing plate 401 extends to the terminal region 40 and is also mechanically reinforced. The terminal area 40 is mounted with a driver IC41 and connected with a flexible wiring substrate 500.

Fig. 2 is a sectional view a-a of fig. 1. In fig. 2, a TFT wiring layer 60 is disposed on an adhesive 4011 of a lower polarizing plate 401. The lower polarizing plate 401, the adhesive 4011, and the TFT wiring layer 60 extend not only in the display region but also in the terminal region 40. The counter substrate 200 and the color filter layer 220 formed on the counter substrate 200 are disposed in a portion corresponding to the display region 30. The color filter layer 220 is a concept including a color filter, a black matrix, an overcoat film, an alignment film, and the like. The counter substrate 200 is formed of a transparent resin.

The liquid crystal layer 300 is sandwiched between the TFT wiring layer 60 and the color filter layer 220. The sealing material 50 bonds the TFT wiring layer 60 and the color filter layer 220, and seals the liquid crystal 300. The upper polarizer 402 is bonded to the counter substrate via the adhesive 4021. The liquid crystal display device has a backlight on the back surface, but is omitted in fig. 2.

Fig. 3 is a plan view of a display region 30 of the liquid crystal display device of the present invention. Fig. 3 shows an example of an IPS (In Plane Switching) liquid crystal display device. In fig. 3, a pixel electrode 112 is formed in a region surrounded by the scanning line 11 and the video signal line 12. In fig. 3, the pixel electrode 112 has 2 slits and is formed of 3 comb-tooth electrodes. Each comb-tooth electrode is bent in the vicinity of the center. This is to make the angle of view characteristic more uniform.

The alignment axis AL of the alignment film defining the initial alignment direction of the liquid crystal molecules is the longitudinal direction (y-direction). The comb electrodes are inclined only by an angle theta with respect to the y-direction. This is to define the rotation direction of the liquid crystal molecules when a voltage is applied between the pixel electrode 112 and the common electrode 110.

The angle of θ is 5 to 15 degrees. By curving the pixel electrode 112, the rotation direction of the liquid crystal is made different between the upper and lower sides in the y direction of the pixel, thereby making the angle of field more uniform. However, the rotation direction of the liquid crystal molecules is not determined at the bent portions of the comb-teeth electrodes, and a so-called domain boundary (domain boundary) occurs. The transmittance is reduced at the region boundary.

In fig. 3, the semiconductor layer 103 is connected to the video signal line at the via hole 131, passes under the scanning line 11 twice, and is connected to the contact electrode 107 at the via hole 132. Since the TFTs are formed at positions below the semiconductor layer 103 passing through the scanning lines 11, 2 TFTs are formed in series in fig. 2. Alternatively, a TFT with a double gate may be formed.

The contact electrode 107 is connected to the pixel electrode 112 at a through hole 130 formed in the organic passivation film. On the organic passivation film, the common electrode 110 is formed in a planar shape (except for the through hole 130 portion). A pixel electrode 112 is formed on a capacitor insulating film formed to cover the common electrode 110.

Fig. 4 is a sectional view of a display region corresponding to fig. 3. As shown in fig. 4, in the present invention, the TFT substrate is not used. As described later, in the initial stage, the TFT wiring layer having the TFTs and the wiring layer formed thereon is formed on the glass substrate and the colored polyimide, and then the glass substrate and the colored polyimide are removed, and the lower polarizing plate is attached to the TFT wiring layer instead of the glass substrate.

A flexible display device using a transparent resin substrate cannot form a TFT using poly-Si due to the limitation of the heat resistance temperature of the resin substrate. In the present invention, colored polyimide is used as a TFT substrate in the manufacturing process, and since the heat resistant temperature of the colored polyimide is higher than that of the transparent polyimide, a TFT can be formed using poly-Si.

In addition, an oxide semiconductor can be used in the present invention. The reliability of the oxide semiconductor is improved by annealing at a high temperature. With the structure of the present invention, annealing can be performed at a high temperature even when an oxide semiconductor is used, and therefore, a highly reliable TFT can be used. In the present invention, a TFT using a-Si (amorphous silicon) can also be formed.

The TFT in fig. 4 is a so-called top gate type TFT, and poly-Si is used as a semiconductor used. On the other hand, in the case of using an a-Si semiconductor, a so-called bottom gate TFT is often used. In addition, an oxide semiconductor can be used in either case. In the following description, a case where a top gate TFT is used will be described as an example, but the present invention is also applicable to a case where a bottom gate TFT is used.

In fig. 4, the first base film 101 is formed of, for example, silicon nitride (hereinafter, represented by SiN), and the second base film 102 is formed of, for example, silicon oxide (hereinafter, represented by SiO). The thickness of the first base film is, for example, 100nm, and the thickness of the second base film is 300 nm. Are formed by CVD (Chemical Vapor Deposition). In the present invention, since the TFT substrate does not exist under the base film, the barrier property by the base film is important.

In order to improve the barrier properties of the base film, the base film may have a 3-layer structure in which SiN is sandwiched between SiO, for example. In this case, for example, the lower SiO film is 300nm, the SiN film is 100nm, and the upper SiO film is 300 nm. The SiO film and the SiN film may be continuously formed by CVD. In fig. 4, the TFT is formed of poly-Si, but there is also a case where the TFT is formed of an oxide semiconductor. The oxide semiconductor is reduced by hydrogen released from SiN, and therefore, the oxide semiconductor cannot be brought into direct contact with SiN. In this case, the uppermost layer of the base film is SiO.

In addition, in order to improve barrier properties, alumina (hereinafter, represented by AlO) may be added to the base film in addition to the SiO film and the SiN film. The AlO film is formed by sputtering. The AlO film is preferably formed before forming the SiO film and the SiN film. The AlO film is formed to a film thickness of, for example, about 50 nm.

In fig. 4, a semiconductor layer 103 is formed over the second base film 102. For this semiconductor layer 103, an a-Si film is formed on the second base film 102 by CVD and converted into a poly-Si film by laser annealing. The poly-Si film is patterned by photolithography.

A gate insulating film 104 is formed over the semiconductor film 103. The gate insulating film 104 is an SiO film using TEOS (Tetraethyl Orthosilicate) as a raw material. The film is also formed by CVD. Over which a gate electrode 105 is formed. The gate electrode 105 also serves as the scanning line 11 shown in fig. 1. The gate electrode 105 is formed of, for example, a MoW film. When it is necessary to reduce the resistance of the gate electrode 105 or the scanning line 10, a gate electrode made of an Al alloy sandwiched by Ti or the like is used.

The gate electrode 105 is patterned by photolithography, and in this patterning, impurities such as phosphorus or boron are doped into the poly-Si layer by ion implantation to form a source electrode S or a drain electrode D in the poly-Si layer.

Then, the gate electrode 105 is covered with SiO or SiN to form an interlayer insulating film 106. The interlayer insulating film 106 is used to insulate the gate electrode 105 from the contact electrode 107, or to insulate the scanning line 11 from the video signal line 12. A through hole 131 for connecting the video signal line 12 and the semiconductor layer 103 is formed in the interlayer insulating film 106 and the gate insulating film 104, and a through hole 132 for connecting the semiconductor layer 103 and the contact electrode 107 is formed.

A double-gate TFT, in which the semiconductor layer 103 passes below the scanning line 11 twice, is formed between the video signal line 12 and the contact electrode 107. Photolithography for forming the through

holes

131, 132 in the interlayer insulating film 106 and the gate insulating film 104 may be performed simultaneously.

A contact electrode 107 is formed on the interlayer insulating film 106. The contact electrode 107 is connected to the pixel electrode 112 via a through hole 130. The contact electrodes 107 and the image signal lines 12 are formed simultaneously in the same layer. In order to reduce the resistance of the contact electrode 107 and the image signal line (hereinafter, represented by the contact electrode 107), an AlSi alloy, for example, may be used. Since AlSi alloy generates hillocks (hillocks) and Al diffuses into other layers, a structure in which AlSi is sandwiched between a barrier layer and a cover layer, which are made of, for example, Ti or MoW, is adopted.

The inorganic passivation film 108 covers the contact electrode 107, thereby protecting the entire TFT. The inorganic passivation film 108 is formed by CVD in the same manner as the first base film 101. The organic passivation film 109 is formed to cover the inorganic passivation film 108. The organic passivation film 109 is formed of a transparent photosensitive acrylic resin. Since the organic passivation film is formed after the TFT is completed, there is no problem of heat resistance, and thus a transparent resin may be used.

The organic passivation film 109 may be formed of a silicone resin, an epoxy resin, a polyimide resin, or the like, in addition to the acrylic resin. The organic passivation film 109 functions as a planarization film and is formed thick. The organic passivation film 109 has a film thickness of 1.5 to 4.5 μm, and is usually about 2 μm.

In order to establish electrical conduction between the pixel electrode 112 and the contact electrode 107, a through hole 130 is formed in the organic passivation film 109. Then, ITO (Indium Tin Oxide) as the common electrode 110 is formed by sputtering, and patterning is performed in such a manner that the ITO is removed from the via hole 130 and the periphery thereof. The common electrode 110 may be formed in a planar shape in common to the pixels.

Next, SiN as the capacitor insulating film 111 was formed over the entire surface by CVD. Then, in the through hole 130, a through hole is formed in the capacitor insulating film 111 and the inorganic passivation film 108 to establish electrical conduction between the contact electrode 107 and the pixel electrode 112. The capacitor insulating film 111 forms a storage capacitor between the common electrode 110 and the pixel electrode 112, and is therefore referred to as a capacitor insulating film.

Then, ITO is formed by sputtering and patterned to form the pixel electrode 112. The shape of the pixel electrode 112 is shown in fig. 2. An alignment film material is applied to the pixel electrode 112 by flexo printing, ink jet, or the like, and fired to form an alignment film 113. For the alignment treatment of the alignment film 113, photo-alignment using polarized ultraviolet light may be used in addition to the rubbing method.

When a voltage is applied between the pixel electrode 112 and the common electrode 110, electric lines of force are generated as shown in fig. 4. The liquid crystal molecules 301 are rotated by the electric field, and the amount of light passing through the liquid crystal layer 300 is controlled for each pixel, thereby forming an image.

In fig. 4, the counter substrate 200 is disposed with the liquid crystal layer 300 interposed therebetween. The counter substrate is formed of a transparent resin. Since there is no high-temperature process on the counter substrate side, a transparent resin such as transparent polyimide can be used. As described later, a material having no birefringence may be selected. The thickness of the counter substrate is 5 μm to 10 μm.

A color filter 201 is formed inside the counter substrate 200. The color filter 201 forms a color image by forming red, green, and blue color filters in each pixel. A black matrix 202 is formed between the color filters 201 and the color filters 201, and the contrast of the image is improved.

An overcoat film 203 is formed to cover the color filter 201 and the black matrix 202. Since the surfaces of the color filter 201 and the black matrix 202 are uneven, the surfaces are flattened by the overcoat film 203. On the overcoat film 203, an alignment film 204 for determining the initial alignment of the liquid crystal is formed. The alignment treatment of the alignment film 204 is performed by a rubbing method or a photo-alignment method in the same manner as the alignment film 113 on the TFT substrate 100 side.

In the case of a liquid crystal display device, since efficiency is poor when the device is manufactured one by one, the following method is adopted: a mother substrate including a plurality of liquid crystal cells is manufactured, and the respective liquid crystal cells are separated from the mother substrate after completion. Fig. 5 shows an example of a mother substrate 600. The example of fig. 5 is an example in which 60 liquid crystal cells 10 are formed on 1 mother substrate 600. In the case of the liquid crystal display device shown in fig. 1, a large number of liquid crystal cells 10 more than 60 can be formed on the mother substrate 600.

Fig. 6 to 20 are views showing a manufacturing process for realizing the liquid crystal display device shown in fig. 1 to 4. In the liquid crystal display device of the present invention, the colored polyimide formed on the glass substrate is used in the manufacturing process, and the glass substrate and the colored polyimide are removed after the liquid crystal display device is completed. Fig. 6 to 12 are processed in a state of the mother substrate, and fig. 13 is processed for each liquid crystal display device.

Fig. 6 is a cross-sectional view showing a state where colored polyimide 100 is formed on a glass substrate 90. The thickness of the glass substrate is, for example, 0.5mm or 0.7 mm. The colored polyimide 100 is formed on the glass substrate 90 in a thickness of 5 to 10 μm. The colored polyimide 100 is formed by applying a precursor as a liquid by a slit coater or the like, and then baking and imidizing the precursor. The colored polyimide 100 has a heat resistant temperature higher than that of the transparent polyimide, and has a heat resistant temperature of, for example, 400 ℃.

Fig. 7 is a cross-sectional view showing a state where a TFT wiring layer 60 is formed on the colored polyimide 100. The TFT wiring layer 60 is a concept including the base film 101 to the pixel electrode 112 in fig. 4. In fig. 7, the TFT wiring layer 60 is illustrated as being divided into a base film 61 and an upper layer 62 above it for convenience.

Since the colored polyimide 100 is peeled off later, the barrier property of the base film 61 is important. The base film 61 includes a laminated film of an SiO film and an SiN film, and is formed of a multilayer inorganic insulating film. The base film 61 may have a SiN film as a lower layer and a SiO film as an upper layer, or may have a SiO film as a lower layer and a SiN film as an upper layer. The base film 61 may have a configuration in which an SiN film is sandwiched between SiO films. In any case, an SiO film and an SiN film may be formed continuously on the colored polyimide by CVD.

The base film 61 may also contain an AlO film. In this case, AlO is formed on the colored polyimide 100 by, for example, sputtering, and an SiO film and an SiN film are formed thereon by CVD. The AlO film is formed to be about 10nm to 50 nm. Although the AlO film has strong adhesion to the colored polyimide 100, the peeling can be easily performed by irradiating the interface with laser light.

In the formation of the upper layer 62 formed on the base film 61, particularly in the case where poly-Si is used in the semiconductor layer, in the annealing of the semiconductor layer, although the colored polyimide substrate 100 undergoes a high temperature of 400 ℃ or higher, the colored polyimide 100 has heat resistance of 400 ℃ or higher. In addition, when an oxide semiconductor is used as the semiconductor layer, if annealing can be performed at a high temperature of 400 ℃.

Fig. 8 is a cross-sectional view showing a state in which an alignment film 113 for aligning liquid crystals is formed on the TFT wiring layer 60. In the figures, the TFT wiring layer 60 may include an alignment film 113.

Fig. 9 is a cross-sectional view showing a state in which the sealing material 50 is formed at the boundary of the liquid crystal cell and the liquid crystal 300 is dropped onto the region surrounded by the sealing material 50. The sealing material 50 may be formed on the counter substrate 200 side. In this case, the liquid crystal 300 is dropped on the counter substrate 200 side.

Fig. 10 is a cross-sectional view showing a state where a separately formed counter substrate 200 is bonded to the colored polyimide 100 side via a sealing material 50. The liquid crystal 300 is sandwiched between the alignment film 113 and the alignment film 204. The manufacturing process of the counter substrate 200 side is as follows. First, the opposite substrate 200, which is formed of a transparent resin such as transparent polyimide, is formed on the glass substrate 210 having a thickness of 0.5mm or 0.7mm to have a thickness of 5 to 10 μm. A color filter layer 220 is formed on the opposite substrate 200. The color filter layer 220 includes the color filter 201, the black matrix 202, and the overcoat film 203 in fig. 4. Then, the alignment film 204 is formed on the color filter layer 220. In the following figures, the color filter layer 220 may include the alignment film 204.

Fig. 11 is a view of fig. 10 turned upside down. Although the structure of fig. 11 is upside down, the structure is the same as that illustrated in fig. 10. In the state of fig. 11, a laser beam is applied to the boundary between the glass substrate 90 and the colored polyimide 100, and the glass substrate 90 and the colored polyimide 100 are separated by so-called laser ablation.

Fig. 12 is a cross-sectional view showing a state where the glass substrate 90 is peeled off by laser ablation. In fig. 12, the colored polyimide 100 is exposed. The mother substrate 600 is processed before the glass substrate 90 is peeled. Then, the respective liquid crystal cells 10 are cut out and separated from the mother substrate 600 by dicing or the like.

Fig. 13 is a cross-sectional view showing a state where the colored polyimide 100 is removed from each liquid crystal cell 10 by oxygen plasma ashing PA. The conditions of oxygen plasma ashing are, for example, O ₂ Flow rate 3000sccm (Standard Cubic Centimeter per minute, Standard Cubic Centimeter p)er minerals), 1800Torr, 2kW, 250 ℃. Under such conditions, the colored polyimide 100 can be removed by ashing at a rate of 10 μm/min.

Fig. 14 is a sectional view showing an apparatus for plasma ashing. The upper diagram of fig. 14 is a cross-sectional view showing a state in which the liquid crystal cell 10 is placed on the lower electrode 701. In fig. 14, an upper electrode 702 for forming plasma is disposed to face the liquid crystal cell 10. The lower diagram of fig. 14 is a cross-sectional view showing a state where the periphery of the liquid crystal cell 10 is pressed by the jig 710 and the colored polyimide 100 on the surface of the liquid crystal cell 10 is removed by the plasma 700.

The sealing material 50 is formed around the liquid crystal cell 10, but the sealing material 50 may be damaged by the plasma 700. To prevent this, the side surface of the liquid crystal cell 10 is covered with the jig 710 so that the plasma 700 does not reach the sealing material 50 while pressing the periphery of the liquid crystal cell 10. The clamp 710 is driven by a motor 711. In the configuration of fig. 14, the plasma 700 does not reach the sandwiched portion, and therefore the colored polyimide 100 is not removed. That is, the colored polyimide 100 partially remains. As long as the remaining portion of the colored polyimide 100 is located outside the display region 30, no problem occurs as a liquid crystal display device.

Fig. 15 is a sectional view showing another example of the plasma ashing apparatus. In the case of fig. 15, plasma ashing is also performed for each liquid crystal cell 10. Fig. 15 differs from fig. 14 in that there is no jig at the periphery of the liquid crystal cell 10, but a mask 720 is formed. Since the mask 720 covers the entire side surface of the liquid crystal cell 10, the protective effect against the sealing material 50 is more excellent. In addition, in the case of the mask 720, the shape can be easily changed according to the region where the colored polyimide 100 is desired to be left.

Fig. 14 and 15 each use a jig 710 or a mask 720 to perform plasma ashing, but the colored polyimide 100 cannot be removed from the clamped or masked portion. When the colored polyimide 100 is intended to be removed from the entire surface of the liquid crystal cell 10, the liquid crystal cell 10 may be simply placed on the lower electrode 701.

Fig. 16 is a cross-sectional view showing a state where the colored polyimide 100 is removed. In fig. 16, the TFT wiring layer 60 has a thickness of only several μm even when the thickest organic passivation film is included, and is extremely weak mechanically. Therefore, in this case, the operation is difficult.

Therefore, as shown in fig. 17, the lower polarizing plate 401 is attached to the TFT wiring layer 60. The thickness of the main body of the lower polarizing plate 401 is about 100 μm, and the adhesive used for attachment is about 10 μm. Therefore, the reinforcing material is sufficient. Since the lower polarizer 401 is an essential element for the liquid crystal display device, the process load is not increased by attaching the polarizer.

Fig. 18 is a cross-sectional view showing a state where fig. 17 is turned upside down in order to process the counter substrate 200 side. Fig. 18 is a view showing only fig. 17 turned upside down, and the structure is the same as that of fig. 17. In fig. 18, the interface between the counter substrate 200 and the glass substrate 210 is irradiated with laser light, and the glass substrate 210 is removed from the counter substrate 200 by laser ablation. Fig. 19 is a cross-sectional view showing a state where the glass substrate 210 is peeled off from the counter substrate 200.

Fig. 20 is a cross-sectional view showing a state where the upper polarizing plate 402 is attached to the counter substrate 200 formed of a transparent resin after the glass substrate 210 is removed. The upper polarizer 402 is attached only to a portion corresponding to the counter substrate 200. On the other hand, the lower polarizing plate 410 is attached to the terminal region 40 in addition to the display region 30. This is to mechanically reinforce the terminal area 40. As shown in examples 3 and 4, the lower polarizing plate 401 may be attached only to the display region 30 by reinforcing the terminal region 40 by another method.

The plasma ashing in fig. 13 is performed for each liquid crystal cell 10, but if the apparatus permits, the plasma ashing may be performed in a state of the mother substrate 200 and then separated into each liquid crystal cell 10. In this case, the colored polyimide 100 can be removed from the entire surface of the liquid crystal cell 10, and if necessary, a part of the colored polyimide 100 may be left and subjected to ashing using a mask.

As described above, according to the present invention, a flexible liquid crystal display device can be formed without a TFT substrate. Therefore, the liquid crystal display device can be formed thin. The transparent polyimide generally used as a TFT substrate has birefringence characteristics. Therefore, light passing through the transparent polyimide is delayed (retadation). The birefringence Δ n of the transparent polyimide was 0.005. When the thickness of the transparent polyimide was 10 μm, the retardation Δ n · d was 50 nm. That is, due to this influence, a contrast reduction due to black floating occurs.

In the present invention, since there is no TFT substrate made of polyimide, the occurrence of the retardation can be prevented, and a high contrast can be maintained. In the present invention, the counter substrate 200 made of resin is present on the counter substrate side. However, since there is no high-temperature process on the counter substrate 200 side, there is a degree of freedom in selecting a resin. That is, a transparent resin material having no birefringence or small birefringence may be selected. Therefore, the contrast can be prevented from being lowered.

[ example 2]

In example 1, in the production process, colored polyimide was formed on a glass substrate, and an underlying film, a TFT, and the like were formed on the colored polyimide, and finally the glass substrate was removed, and the colored polyimide was removed by plasma ashing.

In this example, in the manufacturing process, the a-Si film 95 was used instead of the colored polyimide. When the a-Si film 95 is used, the glass substrate 90 can be removed by laser ablation and the a-Si film 95 can be removed, so that the plasma ashing process can be omitted.

Fig. 21 to 23 are sectional views illustrating a manufacturing process of example 2. Fig. 21 is a cross-sectional view showing a state where an a-Si film 95 is formed on a glass substrate 90. The a-Si film 95 is formed to a thickness of, for example, 50 nm. Fig. 22 is a cross-sectional view showing a state in which the TFT wiring layer 60 is formed on the a-Si film 95. The configuration of the TFT wiring layer 60 is the same as that described in embodiment 1. In fig. 22, a-Si95 is formed instead of the colored polyimide 100, as compared with fig. 7 of example 1.

The processes of fig. 8 to 11 of example 1 are also the same in example 2. That is, in example 2, the colored polyimide was replaced with a-Si in fig. 8 to 11 of example 1.

Fig. 23 is a sectional view showing a state where the glass substrate 90 is removed by laser ablation in example 2. At this time, the a-Si film 95 is removed together with the glass substrate 90. Therefore, a process of plasma ashing is not required. The other constitution is the same as that of fig. 12 of embodiment 1.

In fig. 23, the a-Si film 95 is peeled off together with the glass substrate, but the a-Si film 95 may be attached to the base film side after laser ablation because the a-Si is not strongly adhered to the glass. Even in this case, since a-Si is transparent, it still does not affect the image.

The subsequent process in example 2 is the same as fig. 16 to 20 of example 1. The completed liquid crystal display panel is also configured in the same manner as the configuration described with reference to fig. 1 to 4. The effects of embodiment 2 are also the same as those described in embodiment 1.

[ example 3]

According to the liquid crystal display device, there is a method of using the liquid crystal display device in which the display region 30 is kept flat and the terminal region 40 is bent to reduce the outer shape of the display device. Fig. 24 is a plan view showing such a liquid crystal display device. In fig. 24, a TFT wiring layer 60 extending from the display region 30 is formed in the terminal region 40. The flexible wiring board 500 is connected to the terminal area 40. In fig. 24, the driver IC41 is mounted on the flexible wiring board 500 so as not to interfere with the bending of the terminal region 40.

With the configurations of embodiments 1 and 2, the lower polarizing plate 401 also extends to the terminal region 40. Therefore, the mechanical strength is maintained also in the terminal region 40, but since the mechanical strength of the lower polarizing plate 401 is strong, it is difficult to bend it with a small radius of curvature. Although the lower polarizing plate can be made not to extend to the terminal region 40, if this is done, the mechanical strength of the terminal region 40 becomes extremely weak. Fig. 25 is a sectional view showing such a case.

In fig. 25, the terminal region 40 is constituted only by the TFT wiring layer 60. The thickness tt of the TFT wiring layer 60 is only a few μm in total even when the thickness of the organic passivation film 109 is added. Therefore, a display device with high mechanical reliability cannot be manufactured.

Fig. 26 and 27 are diagrams showing a configuration of a first example of the present embodiment to cope with this. Fig. 26 is a plan view showing a first example of embodiment 3. In fig. 26, the counter substrate 200 extends in the terminal region 40. The counter substrate 200 extends to a terminal portion to which the flexible wiring substrate 500 is connected. In fig. 26, the counter substrate 200 maintains the mechanical strength of the terminal region 40. Since the counter substrate 200 is formed of, for example, a polyimide substrate having a thickness of 5 to 10 μm, the mechanical strength and flexibility can be sufficiently maintained.

Fig. 27 is a cross-sectional view showing a state in which the terminal region 40 is bent in the liquid crystal display device shown in fig. 26. In fig. 27, a terminal region 40 of the liquid crystal display device is bent. Since the thickness tt1 of the terminal region 40 is only 15 μm or less even when the thickness of the opposing substrate is taken, the radius of curvature of the bend can be sufficiently reduced.

In fig. 27, the front end of the flexible wiring substrate 500 overlaps the counter substrate 200. The flexible wiring substrate 500 is electrically connected to the TFT wiring layer 60 at the tip of the terminal region 40 not covered with the counter substrate 200. With the configuration of fig. 27, the terminal region 40 can be bent with a small radius of curvature while maintaining its mechanical strength.

Fig. 28 is a plan view showing a second embodiment of example 3. Fig. 28 differs from fig. 26 as the first embodiment in that the colored polyimide 100 remains in the terminal region 40, and the mechanical strength of the terminal region 40 is enhanced. Accordingly, the counter substrate 200 does not exist on the upper side of the terminal area 40. The counter substrate 200 is formed only in the display region. The colored polyimide 100 can be formed by masking a portion that is desired to remain when the colored polyimide 100 is removed from the display region 30 by plasma ashing.

Fig. 29 is a sectional view showing a feature of the second embodiment. In fig. 29, the colored polyimide 100 remains on the lower surface of the terminal area 40. Since the colored polyimide 100 is removed from the display region 30, the display quality is not impaired. Further, since the colored polyimide 100 is formed on the rear surface of the terminal region 40, the connection of the flexible wiring substrate 500 is not hindered.

In fig. 29, the TFT wiring layer 60 is bonded to the counter substrate 200 with a sealant 50, and the liquid crystal 300 is sealed therein. The colored polyimide 100 overlaps with the sealing material 50 in a plan view. This is to prevent the generation of a portion having only the TFT wiring layer 60. The range d1 where the sealant 50 and the colored polyimide 100 overlap each other is not problematic as long as the range d1 is as wide as the sealant 50.

Fig. 30 is a cross-sectional view showing a state in which the terminal region 40 of the liquid crystal display device shown in fig. 28 and 29 is bent. The upper polarizer 402 and the lower polarizer 401 are both disposed corresponding to the display region 30, and do not affect the bending of the terminal portion 40. The colored polyimide 100 is present in the bent portion, but since the thickness of the colored polyimide 100 is 5 to 10 μm and the thickness tt2 of the terminal region 40 is 15 μm or less in total, the terminal region 40 can be bent with a small radius of curvature without any problem.

Fig. 31 to 33 are views showing a third embodiment of example 3. Fig. 31 is a plan view showing a liquid crystal display device of the third embodiment. Fig. 31 features a terminal area 40. As shown in fig. 31, the flexible wiring substrate 500 is connected to the rear surface side of the terminal region 40. That is, the terminal wiring is formed on the back surface side of the terminal region 40.

Fig. 32 is a cross-sectional view of fig. 31. In fig. 32, the insulating layer 16 includes a base film 101, a gate insulating film 104, and an interlayer insulating film 106. A video signal line 12 is formed in, for example, the display region 30 on the insulating layer 16, and a lead line 15 connected to the video signal line 12 extends in the terminal region 40. In the terminal region 40, the lead wire 15 is exposed to the rear surface of the insulating layer 16 through a through hole formed in the insulating layer 16. The total of the insulating layers 16 is only about 1 μm even when 3 layers are formed. The through-holes of the terminal area 40 may be formed simultaneously with the formation of the through-holes in the display area 30.

In fig. 32, the counter substrate 200 made of a transparent resin is formed up to the end of the terminal region 40 in a plan view. Therefore, the counter substrate 200 can ensure the mechanical strength of the terminal region 40. In fig. 32, since the flexible wiring substrate 500 is connected to the back surface side of the insulating layer 16, even if the counter substrate 200 is formed up to the end of the terminal region 40, the connection of the flexible wiring substrate 500 is not problematic.

Fig. 33 is a cross-sectional view showing a state in which the terminal region 40 is bent in the configuration of fig. 32. Since the thickness of the counter substrate 200 is 5 μm to 10 μm, the total thickness tt3 of the terminal region 40 is only 15 μm or less, and the bending of the terminal region 40 with a small radius of curvature is not hindered. As shown in fig. 33, even if the counter substrate 200 is extended to the end of the terminal region 40, the connection of the flexible wiring substrate 500 is not hindered.

Fig. 34 is a sectional view showing a fourth mode of example 3. Fig. 34 is a structure in which a resin 70 for mechanical reinforcement is applied to the terminal region 40 in the structure of fig. 25. As the resin material, silicone resin, acrylic resin, epoxy resin, or the like can be used, and in the case of an ultraviolet-curable resin, the workability is excellent.

In fig. 34, the end portion of the resin 70 overlaps the counter substrate 200 or the upper polarizing plate 402 on the display region side so that the resin 70 does not peel off from the terminal region 40 against the bending stress. The flexible wiring substrate 500 overlaps with an end portion of the flexible wiring substrate 500. In fig. 34, the counter substrate 200 may protrude outward beyond the upper polarizing plate 402, and therefore the resin 70 may overlap with an end portion of the counter substrate 200.

[ example 4]

Example 4 has the following composition: in the liquid crystal display device, the terminal region 40 is omitted in plan view, and the flexible wiring board and the like are all disposed on the back surface side of the liquid crystal display panel, whereby the outer shape of the liquid crystal display device can be further reduced. Fig. 35 is a plan view of the liquid crystal display device of example 4. In fig. 35, the terminal region 40, the flexible wiring substrate 500, and the like are not present on the surface. The other constitution is the same as that of FIG. 1.

Fig. 36 is a sectional view taken along line B-B of fig. 35. In fig. 36, the TFT substrate is not present. On the insulating layer 16 formed of the base film 101, the gate insulating film 104, and the interlayer insulating film 106, the lead line 15 connected to the display region extends to the vicinity of the end of the interlayer insulating film 106. A through hole is formed in the insulating layer 16 near an end of the interlayer insulating layer 106, and is electrically connected to the driver IC41 disposed on the rear surface side of the insulating layer 16.

The bump 42 in fig. 36 is used in a broad sense as a connection terminal. The bumps 42 of the driver IC41 are connected to the lead lines 15 via, for example, through holes or by an anisotropic conductive film 45. The terminal wiring 45 and the flexible wiring board 500 are also connected via the bump 42. In the configuration of fig. 36, since the terminals are formed on the back surface of the liquid crystal display panel and connected to the driver IC41 and the flexible printed circuit board 500 on the back surface, the flexible printed circuit board 500 and the driver IC41 can be arranged on the back surface of the liquid crystal display panel without bending the flexible printed circuit board 500.

In fig. 36, the organic passivation film 109 is formed so as to cover the lead lines 15. The inorganic passivation film is omitted in fig. 36. A capacitor insulating film 111 is formed on the organic passivation film 109, and an alignment film 113 is formed on the capacitor insulating film.

In fig. 36, a black matrix 202 and a color filter 201 are formed on a counter substrate 200 formed of a resin, and an overcoat film 203 is formed over them. An alignment film 204 is formed to cover the overcoat film 203. The sealing material 50 bonds the alignment film 113 and the alignment film 204, and seals liquid crystal therein.

In fig. 36, an upper polarizing plate 402 is attached to the counter substrate 200. The upper polarizer 402 is formed to an end of the opposite substrate 200. That is, since there is no terminal region on the front surface side of the display device, the upper polarizing plate 402 is disposed up to the end of the display device. On the other hand, since the terminals are formed on the rear surface side of the TFT wiring layer 60, the lower polarizer 401 is disposed so as to avoid this region. Since the lower polarizer 401 covers the range of the display region 30, there is no problem in display quality.

Fig. 37 is a rear view of fig. 35. In fig. 37, the lower polarizing plate 401 covers the entire surface except for a portion where a terminal connected to the driver IC41 or the flexible wiring board 500 is formed. The terminal forming region is also narrow and is disposed in a region overlapping with the sealing material 50 in a plan view. The lower polarizing plate 401 is formed in a sufficient range so as to cover the display area. As shown in fig. 37, the flexible wiring board 500 can be arranged on the back surface of the liquid crystal display panel without being bent.

In fig. 37, although the backlight is omitted, the backlight is disposed between the flexible wiring substrate 500 and the liquid crystal display panel.

Claims

1. A liquid crystal display device in which a liquid crystal is sandwiched between an inorganic insulating film and a counter substrate made of resin, the inorganic insulating film having a laminated structure of a silicon oxide film, a silicon nitride film and an aluminum oxide film and having a plurality of pixels each having a TFT, wherein a lower polarizing plate is bonded to the inorganic insulating film,

the thickness of the aluminum oxide film is 10nm to 50nm,

the lower polarization plate is attached to the aluminum oxide film.

2. The liquid crystal display device according to claim 1, wherein the lower polarizing plate is attached to the inorganic insulating film with an adhesive material.

3. The liquid crystal display device according to claim 1, wherein the inorganic insulating film extends to a terminal region where it is connected to a wiring substrate.

4. The liquid crystal display device according to claim 3, wherein the lower polarizing plate extends in the terminal region and is bonded to the inorganic insulating film.

5. The liquid crystal display device according to claim 3, wherein the counter substrate extends in the terminal region and covers the inorganic insulating film.

6. The liquid crystal display device according to claim 3, wherein a polyimide film is formed on a back surface side of the inorganic insulating film in the terminal region.

7. The liquid crystal display device according to claim 6, wherein the thickness of the polyimide film is 5 to 10 μm.

8. The liquid crystal display device according to claim 3, wherein a lead line extending from a display region is formed on a front surface side of the inorganic insulating film, the lead line is connected to a terminal on a back surface side of the inorganic insulating film through a through hole formed in the inorganic insulating film, and the terminal is connected to the wiring substrate.

9. A liquid crystal display device in which a liquid crystal is sandwiched between an inorganic insulating film and a counter substrate formed of a resin, the inorganic insulating film having a laminated structure of a silicon oxide film, a silicon nitride film, and an aluminum oxide film and having a plurality of pixels each having a TFT formed thereon,

the thickness of the aluminum oxide film is 10nm to 50nm, a lower polarization sheet is bonded on the inorganic insulating film, the lower polarization sheet is attached to the aluminum oxide film, and glass or polyimide is not arranged between the inorganic insulating film and the lower polarization sheet.

10. The liquid crystal display device according to claim 9, wherein the inorganic insulating film extends to a terminal region where it is connected to a wiring substrate, and a polyimide film is formed on a back surface side of the inorganic insulating film in the terminal region.

11. A method for manufacturing a liquid crystal display device, characterized in that,

a polyimide is formed on a first glass substrate,

forming an inorganic insulating film including a plurality of layers on the polyimide, the inorganic insulating film having a laminated structure of a silicon oxide film, a silicon nitride film, and an aluminum oxide film,

forming a layer containing a TFT on the inorganic insulating film,

a counter substrate formed of a transparent resin formed on a second glass substrate and disposed so as to face the layer including the TFT with a liquid crystal interposed therebetween,

then, the first glass substrate and the polyimide are removed, and a lower polarizing plate is attached to the inorganic insulating film,

then, the second glass substrate is removed,

wherein the film thickness of the aluminum oxide film is 10nm to 50nm,

the lower polarization plate is attached to the aluminum oxide film.

12. The method for manufacturing a liquid crystal display device according to claim 11, wherein the inorganic insulating film includes a SiO film and a SiN film, and the SiO film and the SiN film are formed by CVD lamination.

13. The method for manufacturing a liquid crystal display device according to claim 12, wherein the inorganic insulating film further contains an aluminum oxide film, and the aluminum oxide film is formed by sputtering.

14. The method for manufacturing a liquid crystal display device according to claim 11, wherein the polyimide is removed by plasma ashing.

15. A method for manufacturing a liquid crystal display device, characterized in that,

an a-Si film is formed on a first glass substrate,

forming an inorganic insulating film including a plurality of layers on the a-Si film, the inorganic insulating film having a laminated structure of a silicon oxide film, a silicon nitride film, and an aluminum oxide film,

forming a layer containing a TFT on the inorganic insulating film,

a counter substrate made of a transparent resin formed on a second glass substrate, the counter substrate being arranged to face the layer including the TFT with a liquid crystal interposed therebetween,

then, removing the first glass substrate, attaching a lower polarizer to the inorganic insulating film or the a-Si film,

then, the second glass substrate is removed,

wherein the thickness of the aluminum oxide film is 10nm to 50nm,

the lower polarization plate is attached to the aluminum oxide film.

16. The method for manufacturing a liquid crystal display device according to claim 15, wherein the inorganic insulating film includes a SiO film and a SiN film, and wherein the a-Si film, the SiO film, and the SiN film are formed by CVD.