JPH06258662A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To increase an opening rate and to flatten element substrates so as to obtain high-quality display free from disturbance in a liquid crystal by separating signal lines and pixel electrodes with an interlayer insulating film. CONSTITUTION:A pixel driving transistor(TR) 301 and a driver circuit 303 are formed on the element substrate 301. A first wiring layer 304 including scanning lines, the pixel driving TR 302 and a gate electrode of the driver circuit 303, the first interlayer insulating film 305 and a second wiring layer 306 including the signal lines are formed at this time. The second interlayer insulating film 307 and a pixel electrode 308 are then formed and are connected to the pixel driving TR 302 through a contact hole opened in the second interlayer insulating film 307. Further, an oriented film 309 is formed. A transparent resin thin film having a high heat resistance is usable in addition to a polyimide thin film for the second interlayer insulating film 307. The signal lines and the pixel electrodes are separated by the interlayer insulating film 307, according to this constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field 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 displaying by using liquid crystal sealed between two substrates.

[0002]

2. Description of the Related Art An example of a conventional active matrix type 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. 1A is a schematic external view of a conventional liquid crystal display device, FIG. 1B is a vertical sectional view taken along the line AA of FIG. 1A, and FIG.
It is a BB vertical cross-sectional view of (a). The driver circuit 1 for the display region 102, the scanning lines and the signal lines is provided on the element substrate 101.
03 and 104, the external connection terminal 105 is formed, the counter substrate 106 is bonded to the element substrate 101 by the seal 107, and the liquid crystal 108 is provided between the element substrate 101 and the counter substrate 106.
Is enclosed. The common electrode 10 is provided on the counter substrate 106.
9 is provided, and the common electrode 109 is connected to the common terminal 110 on the element substrate 101 by the conducting agent 111.
Further, a light shielding layer 112 is provided on 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. Pixel driving transistor 113 and driver circuit 103 (104)
The first wiring layer 115 including the gate electrode and the scanning line is separated from the second wiring layer 117 by the interlayer insulating film 116, and is connected to the second wiring layer 117 at a necessary position. The second wiring layer 117 includes a signal line in the display area, and includes the pixel electrode 114.
It is provided in the same layer as. An upper layer of the second wiring layer 117 is a liquid crystal protective insulating film 118, which is provided to prevent signals of the second wiring layer 117 from directly leaking to the liquid crystal. The liquid crystal protective insulating film 118 is usually removed on the pixel electrode 114.
An alignment film 1 is further formed on the element substrate 101 and the counter substrate 106.
There is 19.

In the liquid crystal display device shown in 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 to avoid a short circuit. Does not contribute to the display. This hinders the 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 reduce the distance between the pixel electrode and the signal line while avoiding a short circuit between the pixel electrode and the signal line, or In some cases, a method of overlapping the pixel electrodes may be adopted. As the interlayer insulating film on the signal line, an organic thin film such as SiO2 or polyimide is used. The interlayer insulating film on the signal line is easy to form, has a small dielectric constant (to reduce the coupling capacitance between the signal line and the pixel electrode), and is easy to be thick due to the small stress (dielectric constant and For the same reason), and further, since the flatness of the film surface is easily made better than that of SiO2, it is advantageous to use polyimide from the viewpoint of good display quality.

[0004]

In the conventional liquid crystal display device shown in FIG. 1, since the driver circuit is located outside the seal, the size of the device itself becomes large, and the driver circuit is easily damaged during handling. There was a problem that it was easy to invite. Also, because the driver circuit is outside the seal, the wiring that crosses the seal (signal line and scan line)
In particular, in order to increase the aperture ratio, an interlayer insulating film (hereinafter, an interlayer insulating film between the first wiring layer and the second wiring layer is referred to as the first interlayer insulating film and the second wiring layer) on the signal line. When the interlayer insulation on the (signal line) is used as the second interlayer insulation film) to insulate the pixel electrode and the signal line, if the second interlayer insulation film is polyimide, the wiring from the driver circuit and There is a problem that water penetrates into the liquid crystal through the interface of the polyimide and deteriorates the display.

[0005]

A liquid crystal display device of the present invention covers a driver circuit, an element driving thin film transistor, a signal line and a scanning line formed on an element substrate with an organic film,
The pixel electrode is provided on the organic film to insulate the signal line from the pixel electrode, and the driver circuit is arranged immediately below a seal for joining the element substrate and the counter substrate.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The active matrix type liquid crystal display device with a built-in driver circuit of the present invention and the manufacturing process thereof will be described in detail below with reference to embodiments.

FIG. 2 shows the structure of the liquid crystal display device of this embodiment. FIG. 2A is an external view of the liquid crystal display device of this embodiment, and FIGS. 2B and 2C are A of FIG. 1A.
It is a longitudinal cross-sectional view in -A, BB. A display area 202 driver circuit 203, an external connection terminal 204, a common terminal 205, and wirings connecting these are formed on the transparent element substrate 201, and the element substrate 201 and the counter substrate 207 are joined by a seal 206, Liquid crystal is enclosed between both substrates. At this time, the driver circuit 20
3 and the seal 206 overlap each other. Display area 20
2 includes a pixel driving transistor 208, a pixel electrode 209,
A first wiring layer 211 including a scan line, a pixel driving transistor 208, and a gate electrode of the driver circuit 203, and a second wiring layer 212 including a signal line are formed, and the first wiring layer 211 and the second wiring layer 212 are formed. Is the first interlayer insulating film 213
In addition, the second wiring layer 212 and the pixel electrode 210 are
Are insulated by the interlayer insulating film 214. Element substrate 201
An alignment film 215 for further aligning the liquid crystal is formed on the top. The common terminal 205 and the common electrode 216 on the counter substrate 207 are electrically connected by the conducting agent 217, and the potential of the common electrode 216 is controlled. In addition to the common electrode 216, an alignment film 215, a light-shielding film 218 and a color filter are formed in advance on the counter substrate 207, if necessary.
(In this embodiment, the color filter is omitted.) The portion of the common electrode 216 on the counter substrate 207 which overlaps with the seal 206 is preferably not removed in the manufacturing process.
By removing the driver circuit 20 on the element substrate 201
3 and the common electrode 216 may be removed in order to prevent short circuit due to dust or the like in the seal 206.

Next, the manufacturing process of the liquid crystal display device of this embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating a manufacturing process with a vertical cross section of a portion corresponding to FIG. 2B for explaining the structure of the liquid crystal display device of the present embodiment.

First, the pixel driving transistor 302 and the driver circuit 303 are formed on the element substrate 301. Scanning line / pixel driving transistor 302 and driver circuit 3
A first wiring layer 304 including a gate electrode of No. 03, a first interlayer insulating film 305, and a second wiring layer 306 including a signal line are formed at this time (FIG. 3A). 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 is a silicon oxide film (SiO ₂ ) or a silicon nitride film (Si ₃ N ₄ ). ,
Alternatively, it is a multilayer film of them. An aluminum (Al) alloy (including copper and silicon) is usually used for the second wiring layer 306.

Next, a second interlayer insulating film 307 is formed on the element substrate 301, and a pixel electrode 308 is formed thereon,
A second interlayer insulating film 307 is formed on the pixel driving transistor 302.
Connect through the contact hole opened in the. Further, an alignment film 309 is formed (FIG. 3B). Second interlayer insulating film 3
Although 07 is a polyimide thin film here, other resin thin films can be used as long as they have relatively high heat resistance and are transparent. The pixel electrode 308 is indium tin oxide (ITO). 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 in a portion necessary for aligning the liquid crystal. Alignment film 309
May be formed by spin coating. Pixel electrode 3
If ITO is etched with an aqua regia etchant (aqueous solution containing at least nitric acid and hydrochloric acid) when forming 08, the second wiring layer 306 (Al alloy) corrodes when it comes into contact with the ITO etchant. At least the second interlayer insulating film 307 or ITO (pixel electrode 308) is provided on the wiring layer 306. When the ITO (that is, the pixel electrode 308) is formed by etching in plasma containing hydrogen or methane, for example, the second wiring layer 306 may be exposed. In this embodiment, the ITO (pixel electrode 308) is etched with an aqua regia-based etching agent,
The portion where the second wiring layer 306 needs to be exposed, that is, the external connection terminal (204 in FIG. 2A), has the second interlayer insulating film 307 thereon removed again in a later step. In order to expose the external connection terminal, a method of removing the second interlayer insulating film 307 by a photolithographic technique after forming the pixel electrode and a method of joining the element substrate 301 and the counter substrate 311 and then using oxygen plasma or the like are used. There is a method of removing the second interlayer insulating film outside the counter substrate 311.

The element substrate 301 on which the alignment film 309 is formed is bonded to the counter substrate 311 with a seal 310, and the liquid crystal 312 is sealed. The seal 310 is formed so as to overlap with the driver circuit 303. Second with oxygen plasma 313
By removing the second interlayer insulating film 307 on the wiring layer 306, the external connection terminals are exposed (FIG. 3C) and connected to an external circuit to complete the liquid crystal display device. By leaving the second interlayer insulating film 307 under the seal 310 without removing it,
The driver circuit can be protected from the gap material that may be included in the seal.

[0012]

In the liquid crystal display device of the present invention, since the signal line and the pixel electrode are formed in different layers using polyimide as an interlayer insulating film, the aperture ratio is large and the surface of the element substrate is flat, so that the liquid crystal is aligned. High-quality display can be obtained without disturbance.
Furthermore, since the driver circuit on the element substrate is under the seal, hundreds of signal lines and scanning lines extending from the driver circuit to the pixel area do not cross the seal, and wiring that crosses the seal is connected from the external connection terminal to the driver circuit. Power supply lines, clock lines, video signal lines, etc. connected to the can be significantly reduced compared to the conventional one, so that water entering from the interface between the wiring crossing the seal and the polyimide can be significantly reduced, and the reliability is high. Further, since the driver circuit is below the seal, there is an effect that the device can be made smaller than when the driver circuit is outside the seal.

[Brief description of drawings]

FIG. 1 is a structural diagram of a conventional active matrix type liquid crystal display device with a built-in driver circuit.

FIG. 2 is a structural diagram of an active matrix type liquid crystal display device incorporating a driver circuit of the present invention.

FIG. 3 is a process diagram illustrating a method for manufacturing an active matrix type liquid crystal display device having 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 ... Opposing substrate 107, 206, 310 ... Seal 108, 209, 312 ... Liquid crystal 109, 218 ... Common electrode 110, 205 ... Common terminal 111, 217 ... Conducting agent 112, 216 ... Shading layer 113, 207, 302 ... Pixel driving transistor 114, 210, 308 ... Pixel electrode 115, 211, 304 ... First wiring layer 116 ... Interlayer insulating film 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 313 ... Oxygen plasma

Claims (1)

[Claims] 1. A pixel electrode arranged in a matrix, a pixel driving thin film transistor connected to each of the pixel electrodes, a set of signal wirings connected to the pixel driving thin film transistor and a set of scanning wirings, and the signal. An active matrix type including an element substrate having a driver circuit for driving the wiring and the scanning wiring, an opposing substrate having a common electrode facing the element substrate, and a liquid crystal sealed between the element substrate and the opposing substrate. In the liquid crystal display device, there is an organic film on the pixel driving thin film transistor on the element substrate, the signal line, the scanning line and the driver circuit, and the pixel electrode on the organic film,
The liquid crystal display device is characterized in that the driver circuit on the element substrate is under a seal portion for joining the element substrate and the counter substrate and at the same time sealing liquid crystal.