JP3803640B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure of an active matrix type liquid crystal display device integrally formed with a driver circuit for performing display using liquid crystal sealed between two substrates.
[0002]
[Prior art]
An example of a conventional active matrix liquid crystal display device with a built-in driver circuit (hereinafter simply referred to as a liquid crystal display device) will be described with reference to FIG. FIG. 1A is a schematic external view of a conventional liquid crystal display device, FIG. 1B is a longitudinal sectional view taken along line A-A in FIG. 1A, and FIG. 1C is FIG. FIG. A display region 102, driver circuits 103 and 104 for scanning lines and signal lines, and external connection terminals 105 are formed on the element substrate 101, and the counter substrate 106 is bonded to the element substrate 101 with a seal 107. A liquid crystal 108 is sealed between 106. A common electrode 109 is provided on the counter substrate 106, and the common electrode 109 is connected to a common terminal 110 on the element substrate 101 by a conductive agent 111. In addition, a light shielding layer 112 is provided over the counter substrate 106. A pixel drive transistor 113 is provided in the display region 102 of the element substrate 101, and a pixel electrode 114 is connected to the pixel drive transistor 113. The first wiring layer 115 including the gate electrodes and the scanning lines of the pixel driving transistor 113 and the driver circuit 103 (104) is separated from the second wiring layer 117 by the interlayer insulating film 116, and the second wiring layer is formed at a necessary position. 117 is connected. The second wiring layer 117 includes a signal line in the display region and is provided in the same layer as the pixel electrode 114. The upper layer of the second wiring layer 117 is a liquid crystal protective insulating film 118 and is provided to prevent the signal of the second wiring layer 117 from leaking directly to the liquid crystal. The liquid crystal protective insulating film 118 is usually removed on the pixel electrode 114. An alignment film 119 is further provided on the element substrate 101 and the counter substrate 106.
[0003]
In the liquid crystal display device of FIG. 1, the pixel electrode 114 and the signal line (second wiring layer 117) are in the same layer, and it is necessary to secure a certain distance in order to avoid a short circuit. do not do. This hinders high aperture ratio and high definition of the liquid crystal display device. In order to solve this problem, an interlayer insulating film is further provided on the signal line, and a pixel electrode is provided on the upper layer to insulate the pixel electrode from the signal line, thereby reducing the distance between the pixel electrode and the signal line, or There are cases where a method of overlapping pixel electrodes is used. The interlayer insulating film on the signal line is an organic thin film such as SiO ₂ or polyimide. The interlayer insulating film on the signal line is easy to form, has a low dielectric constant (to reduce the coupling capacitance between the signal line and the pixel electrode), and can be easily thickened due to low stress (with a dielectric constant and For the same reason), it is advantageous to use polyimide from the viewpoint of good display quality because the flatness of the film surface is easier to improve than that of SiO ₂ .
[0004]
[Problems to be solved by the invention]
In the conventional liquid crystal display device as shown in FIG. 1, since the driver circuit is outside the seal, the device itself becomes large, and the driver circuit is not handled during the manufacturing process after joining the element substrate and the counter substrate. There was a problem that it was easy to damage and cause a failure. In addition, since the driver circuit is outside the seal, there are many wirings (signal lines and scanning lines) that cross the seal, and moisture penetrates into the liquid crystal through the interface between the driver circuit and the display area, and the liquid crystal There was a problem of deteriorating.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a liquid crystal sandwiched inside a seal portion between a pair of substrates, a pixel transistor formed in a display region on one of the pair of substrates, and the pixels A wiring connected to the transistor; a pixel electrode provided via an organic insulating film formed on the wiring connected to the pixel transistor; and the display inside the seal portion and outside the display region A plurality of driver circuits provided corresponding to the sides of the region, transistors constituting the driver circuit, and wirings connected to the pixel transistors are provided in the same layer and connected to the transistors constituting the driver circuit. Wiring extending to the pixel transistor side, and the organic insulating film includes a transistor constituting the driver circuit and a transistor constituting the driver circuit. Wiring connected to Njisuta, and the seal portion to provide a liquid crystal display apparatus characterized by not disposed.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The active matrix liquid crystal display device with a built-in driver circuit of the present invention and the manufacturing process thereof will be described in detail based on embodiments.
[0007]
FIG. 2 shows the structure of the liquid crystal display device of this embodiment. 2A is a plan view of the liquid crystal display device of this embodiment, and FIGS. 2B and 2C are longitudinal sectional views taken along lines AA and BB in FIG. 2A, respectively. is there. On the transparent element substrate 201, a display region 202, a driver circuit 203, an external connection terminal 204, a common terminal 205, a wiring for connecting them, and the like are formed. The element substrate 201 and the counter substrate 207 are joined by a seal 206. The liquid crystal 208 is sealed between the substrates. The driver circuit 203 is provided between the seal 206 and the display area 202. By doing so, the liquid crystal display device can be made smaller than when the driver circuit 203 is outside the display region 202. In the display region 202, the scanning lines included in the first wiring layer 211 and the signal lines included in the second wiring layer 212 are included together with the pixel driving transistor 209, the pixel electrode 210, the pixel driving transistor 209, and the gate electrode of the driver circuit 203. The first wiring layer 211 and the second wiring layer 212 are insulated by the first interlayer insulating film 213, and the second wiring layer 212 and the pixel electrode 210 are insulated by the second interlayer insulating film 214. Yes. The second interlayer insulating film 214 is removed on the driver circuit 203 and the portion below the seal 206. This is due to the fact that the second interlayer insulating film 214, which is mainly made of polyimide, causes a constant polarization due to the electric field of the wiring of the driver circuit 203, and disturbs the orientation of the liquid crystal over a large area in the long term. The purpose is to prevent the deterioration of the liquid crystal and also prevent moisture and impurities from entering the liquid crystal through the polyimide. On the element substrate 201, an alignment film 215 for aligning liquid crystal is further formed. The common terminal 205 and the common electrode 216 on the counter substrate 207 are electrically connected by a conductive agent 217, and the potential of the common electrode 216 is controlled. On the counter substrate 207, in addition to the common electrode 216, an alignment film 215 and, if necessary, a light shielding film 218 and a color filter are formed in advance. (In this embodiment, the color filter is omitted.) The common electrode 216 on the counter substrate 207 has a portion overlapping the seal 206 and a portion facing the driver circuit 203 removed. By doing so, wiring other than the common terminal 205 on the element substrate 201 and the common electrode 216 are prevented from being short-circuited due to dust or the like in the seal 206 or the driver circuit 203.
[0008]
Next, the manufacturing process of the liquid crystal display device of the present embodiment will be described with reference to FIG. FIG. 3 is a diagram for explaining the manufacturing process in a longitudinal section of a portion corresponding to FIG. 2B for explaining the structure of the liquid crystal display device of this embodiment.
[0009]
First, the pixel driving transistor 302 and the driver circuit 303 are formed on the element substrate 301. At this time, the first wiring layer 304 including the scanning line and pixel driving transistor 302 and the gate electrode of the driver circuit 303, the first interlayer insulating film 305, and the second wiring layer 306 including the signal line are formed (FIG. 3). a)). In this embodiment, the pixel transistor 302 and the driver circuit 303 are composed of polycrystalline silicon thin film transistors. Polycrystalline silicon is used for the first wiring layer 304, but metal silicide or metal may be used, and the first interlayer insulating film 305 may be a silicon oxide film (SiO ₂ ) or a silicon nitride film (Si ₃ N ₄ ). Or a multilayer film thereof. For the second wiring layer 306, an aluminum (Al) alloy (including copper and silicon) is usually used.
[0010]
Next, a second interlayer insulating film 307 is formed on the element substrate 301, and a pixel electrode 308 is formed thereon, and is connected to the pixel driving transistor 302 through a contact hole opened in the second interlayer insulating film 307. Further, an alignment film 309 is formed (FIG. 3B). 3B will be described in more detail. In this embodiment, after the second interlayer insulating film 307 (here, polyimide) is applied by spin coating, the pixel electrode 308 and the pixel transistor 302 are formed. A contact hole to be connected is formed by a photolithography method so that the second wiring layer 306 is not exposed at this time. That is, the second interlayer insulating film 307 still remains at this point on the driver circuit 303 and below the seal. Next, the pixel electrode 308 is formed, and then the second interlayer insulating film 307 on the driver circuit 303 and under the seal is removed. When indium tin oxide (ITO) is used for the pixel electrode 308 and an aqua regia type etching agent (an aqueous solution containing nitric acid and hydrochloric acid) is used for the etching molding, the second wiring layer 306, that is, Al is exposed. This is because Al is attacked by the etching agent of ITO. When the ITO (that is, the pixel electrode 308) is formed by etching in a plasma containing, for example, hydrogen or methane, the second wiring layer 306 may be exposed. Therefore, the second interlayer insulating film 307 is formed by 1 step. It can also be made times. The second interlayer insulating film 307 is a polyimide thin film here, but other resin thin films have relatively high heat resistance and can be used if they are transparent. The second interlayer insulating film 307 may be a multilayer film of polyimide and SiO ₂ or Si ₃ N ₄ . In this case, it is necessary to remove the second interlayer insulating film 307 on the driver circuit 303 and under the seal without fail, and the other may be left or removed. The alignment film 309 is also a polyimide thin film, and is formed using a printing technique (flexographic printing or the like), and is formed only on a portion necessary for aligning the liquid crystal. The alignment film 309 may be formed by a spin coating method.
[0011]
The element substrate 301 on which the alignment film 309 is formed is bonded to the counter substrate 311 with a seal 310 to enclose the liquid crystal 312 (FIG. 3C). Further, an external circuit is connected to the external connection terminal to complete the liquid crystal display device.
[0012]
【The invention's effect】
According to the present invention having the above configuration, the following effects are produced.
(1) Since the driver circuit on the element substrate is closer to the display area than the seal, hundreds of signal lines and scanning lines extending from the driver circuit to the pixel area do not cross the seal, and the wiring crossing the seal is connected externally. Dozens of power lines, clock lines, video signal lines, etc. connected to the driver circuit from the terminal can be remarkably reduced compared to the conventional, so the moisture that penetrates from the wiring across the seal and the seal interface can be remarkably reduced, and the reliability is high. .
(2) Since the driver circuit is inside the seal, there is an effect that the device can be made smaller than when the driver circuit is outside the seal, and the driver circuit is damaged by handling after joining the element substrate and the counter substrate. There is no such thing.
(3) The second wiring layer and the pixel electrode are insulated by the second interlayer insulating film, and this second interlayer insulating film is formed by removing portions on the driver circuit and below the seal. The second interlayer insulating film, which uses polyimide for the electrode, causes permanent polarization by the electric field of the wiring of the driver circuit, and prevents deterioration of display quality due to disturbing the alignment of the liquid crystal over a large area in the long term. it can.
[Brief description of the drawings]
FIG. 1 is a structural diagram of a conventional active matrix liquid crystal display device with a built-in driver circuit.
FIG. 2 is a structural diagram of an active matrix liquid crystal display device incorporating a driver circuit according to the present invention.
FIG. 3 is a process diagram illustrating a method for manufacturing an active matrix liquid crystal display device with a driver circuit according to the present invention.
[Explanation of symbols]
101, 201, 301 Element substrate 102, 202 Display area 103, 104, 203, 303 Driver circuit 105, 204 External connection terminal 106, 207, 311 Counter substrate 107, 206, 310 Seal 108, 208, 312 Liquid crystal 109, 216 Common Electrodes 110, 205 Common terminals 111, 217 Conductive agents 112, 218 Light shielding layers 113, 209, 302 Pixel drive transistors 114, 210, 308 Pixel electrodes 115, 211, 304 First wiring layer 116 ... Interlayer insulating films 117, 212, 306 Second wiring layer 118 Liquid crystal protective insulating film 119, 215, 309 Alignment film 213, 305 First interlayer insulating film 214, 307 Second interlayer insulating film

Claims (1)

A liquid crystal sandwiched inside a seal portion between a pair of substrates;
A pixel transistor formed in a display region on one of the pair of substrates;
A wiring connected to the pixel transistor;
A pixel electrode provided via an organic insulating film formed on a wiring connected to the pixel transistor;
A plurality of driver circuits provided on the inner side of the seal part and on the outer side of the display area, corresponding to the sides of the display area;
A transistor constituting the driver circuit;
Provided in the same layer as the wiring connected to the pixel transistor, and has a wiring connected to the transistor constituting the driver circuit and extending to the pixel transistor side,
2. The liquid crystal display device according to claim 1, wherein the organic insulating film is not disposed on a transistor constituting the driver circuit, a wiring connected to the transistor constituting the driver circuit, and the seal portion .

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