JPH06160904A - Liquid crystal display device and its production - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display device which decreases the man- hours for production, lowers the disconnection defects generation rate of respective wirings and to lower the resistance of respective wirings relating to the structure of the active matrix type liquid crystal display device constituted by using thin-film transistors (TFTs) switching elements and the process for production of such structure. CONSTITUTION:Scanning lines for driving TFTs and signal wirings are constituted by simultaneously forming the first signal wirings 17 (b) which are a part of the signal wirings at the time of forming the first scanning wirings 17 (a), further, forming the second scanning wirings 16 (b) which are a part of the scanning wirings at the time of forming the second signal wirings 16 (a) and bringing the respective wirings into electrical contact partially with each other via aperture contact parts 18, 19. As a result, the number of patterning times is decreased and since the respective wirings can be made into redundancy constitution, there are the effect of decreasing man-hours for production, drastically lessening the disconnection defect generation rate of the respective wirings and preventing the delaying of the signals by the lowered resistance of the respective wirings.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to an active matrix liquid crystal display device using a thin film transistor as a switching element and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, due to advances in fine processing technology and liquid crystal materials, television image display devices using liquid crystal panels have been provided on a commercial basis. Further, as the method, a so-called active matrix method in which a switching element is built in each pixel is becoming mainstream because of advantages such as high contrast and high resolution.

FIG. 4 is an equivalent circuit of an active matrix type liquid crystal panel. For each intersection of the scanning line group 1 and the signal line group 2, for example, a switching element of a field effect type thin film transistor (hereinafter referred to as a field effect type transistor). 3 and the liquid crystal cell 4 are arranged. Reference numeral 5 is a counter electrode made of a transparent conductive layer common to all liquid crystal cells 4.

FIG. 5 is a plan view of a unit pixel of a general active matrix system, and FIG. 6 is a sectional view taken along the line AA 'in FIG. A conventional liquid crystal panel will be described below with reference to the drawings.

Pixel electrodes 6 are selectively formed on one main surface of a transparent insulating substrate 14, for example, a glass substrate, by using a transparent conductive layer such as ITO. Then, the conductive layer 7 that also serves as the scanning line (scanning electrode) and the gate of the field effect transistor is formed as the first layer.
Conductive layer 7 (a) of, for example, a Cr thin film, and the second conductive layer 7
(B) Selectively deposit by, for example, continuous lamination with a MoSi ₂ thin film. Next, the first insulating layer 15 made of, for example, Si ₃ N ₄ , the first amorphous silicon layer 11 containing almost no impurities, and the second insulating layer 13 are made of, for example, Si ₃ N ₄ , preferably continuously. Put on. Then, the second insulating layer 13 is patterned in an island shape on the channel portion of the field effect transistor as an etching stopper at the time of forming the source / drain wiring. Next, for the purpose of improving the ohmic property between the first amorphous silicon layer 11 and the source / drain wirings 8 and 9, a second amorphous silicon layer 12 containing, for example, phosphorus is deposited, and then a second amorphous silicon layer 12 is deposited. Simultaneously with the first amorphous silicon layer 11, the island-shaped patterning is performed on the channel portion of the field effect transistor. Finally, the signal line (signal electrode) 8 and the drain wiring 9 are, for example,

[0006]

[Outer 1]

The liquid crystal display device is completed by selectively forming and depositing with.

[0008]

In order to achieve higher density and larger screen of the liquid crystal panel, it is desired to make the image display defect-free. However, the above-mentioned configuration has a problem that it is very difficult to realize defect-free because the structure and manufacturing process are complicated. One of the reasons that makes it difficult to eliminate defects is a defect (disconnection) in the signal wiring and the scanning wiring. As a method of actually preventing disconnection, a structure is adopted in which each wiring has a two-layer structure and each layer compensates for a disconnection defect generated in each layer. However, in this structure, since each wiring has a two-layer structure, it is necessary to form the pattern for each wiring twice when forming the wiring, and therefore the photoetching process is originally required from the formation of the conductive layer for wiring. The number of man-hours is doubled, and there is a big problem in cost reduction. Further, there is a problem that the resistance value of the signal wiring and the scanning wiring increases as the screen size increases. In particular, an increase in the resistance of the scanning wiring causes a signal delay, which causes a luminance gradient in the image signal wiring direction, which is a serious problem.

In view of the above problems, the present invention provides a liquid crystal display device having a structure for preventing the occurrence of disconnection defects in signal wirings and scanning wirings without increasing the number of steps and further reducing the resistance of both wirings. It is a thing.

[0010]

SUMMARY OF THE INVENTION In view of the above, the present invention is directed to forming a scanning wiring, forming a part of the first signal wiring at the same time as the first scanning wiring, and transmitting a signal through an insulating layer. When forming the wiring, the second signal wiring and the second scanning wiring are simultaneously formed. At this time, the first scan wiring and the second scan wiring, and the first signal wiring and the second signal wiring are electrically connected to each other through an opening previously formed in a part of the insulating layer. Thus, scanning wiring and signal wiring are formed.

[0011]

According to the present invention, since the scanning wiring and the signal wiring can be formed in a plurality of layers by using the same conductive layer as the above structure, a disconnection occurs in one conductive layer. However, the defect can be compensated by another conductive layer. Particularly, only by forming the respective layers of the scanning wiring and the signal wiring, each wiring has a two-layer structure except a part, and it is possible to reduce the number of manufacturing steps while maintaining high quality.
Further, since the scanning wiring and the signal wiring are composed of a plurality of conductive layers, it is possible to reduce the resistance of each wiring. For example, in the scanning wiring, the luminance in the scanning wiring direction due to the delay of the applied scanning signal. It is also possible to take measures against image defects such as tilting and achieve a low resistance of the gate wiring sufficient to provide a normal image.

[0012]

1 is a plan view of a unit pixel of an active matrix type liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line AA 'in FIG. B '
A cross-sectional view on the line is shown in FIG. 3, respectively.

First, as shown in FIG. 1, a pixel electrode 20 made of a transparent electrode is pattern-formed on a glass substrate, and the pixel electrode 20 is electrically separated from the pixel electrode 20.
7 (a) and the first signal wiring 17 which becomes a part of the signal wiring
Further, (b) is electrically separated from the first scanning wiring 17 (a), and is patterned by a photoetching method using a conductive layer made of the same layer (for example, Cr, (outer 1), etc.). Next, on the first scanning wiring 17 (a) and the first signal wiring 17 (b), as shown in FIGS. 2 and 3, the second signal wiring 16 (a) and the second signal wiring 16 (a) formed later are formed. The first insulating layer 26 (for example, Si ₃ N ₄ ) for maintaining insulation with the second scanning wiring 16 (b) is at least the first scanning wiring 17
(A) and the first signal wiring 17 (b). Further, in the field effect transistor portion, the first amorphous silicon layer 21 containing almost no impurities and the second insulating layer 22 are continuously deposited on the first insulating layer 26, and then the first insulating layer 26 is formed. The second insulating layer 22 is used as an etching stopper at the time of forming the second signal wiring 16 (a), the second scanning wiring 16 (b), and the drain wiring 23, which will be formed later, in the channel portion of the electric field transistor. Pattern. Next, the first amorphous silicon layer 21 and the second signal wiring 16
In order to improve ohmic contact between (a) and the drain wiring 23, the second amorphous silicon layer 25 containing, for example, phosphorus is deposited, and then the same as the first amorphous silicon layer 21. Then, an island pattern is formed on the channel portion of the field effect transistor. Next, the second signal wiring 16 to be formed later is formed.
(A), the second scanning wiring 16 (b), the drain wiring 23, and the respective wirings, and the opening contact portions 18, 19, 24 for electrically connecting with the electrodes are provided. Next, a conductive layer is formed on the substrate provided with the opening contact portions, and the conductive layer is patterned to electrically separate the second signal wiring 16 (a) from the second signal wiring. The second scanning wiring 16 (b) and the drain wiring 23 are formed.

In this state, the first scanning wiring 17
(A) and the second scanning wiring 16 (b) are the second scanning wiring 1
Electrical continuity is obtained by the opening contact portions 19 provided at both ends of 6 (b) (see FIG. 2), and similarly, the first signal wiring 17 (b) and the second signal wiring 16 are also provided.
In (a), electrical continuity is obtained by the opening contact portion 18 (see FIG. 3). Further, the drain wiring 23 can be electrically connected by the pixel electrode 20 and the opening contact portion 24. Here, the first scan line 17 (a) and the second scan line 17 (a)
It is possible to supply a signal to each pixel by forming the signal wiring 16 (a) as a continuous wiring for each pixel.

As described above, in this embodiment, in the active matrix type liquid crystal display device, the first signal wiring which becomes a part of the signal wiring when forming the first scanning wiring, and the second signal wiring are formed. When forming the signal wiring, a part of the second scanning wiring is formed, and each of the first wiring and the second wiring is provided with an opening portion in a part of a layer provided therebetween, and electrically. It is designed to make contact. With this structure, the two layers of the scanning wiring and the signal wiring can be made redundant, and the disconnection defect of each wiring can be greatly reduced. Further, since each wiring has a two-layer structure, it is possible to reduce the resistance of each wiring.

[0016]

As described above, according to the present invention, both the scanning wiring and the signal wiring can be redundantly configured by performing the patterning once, thereby reducing the number of times of patterning and Due to the redundant configuration, even if a wire breakage occurs in one wire, the other wire can cover the wire breakage, and the manufacturing yield can be dramatically improved while reducing the man-hours. Further, since each wiring has a two-layer structure, each wiring resistance can be reduced, and the reduction in resistance is effective for the delay problem of each signal.

[Brief description of drawings]

FIG. 1 is a plan view of a main part of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view of the main part of the same device.

FIG. 3 is a sectional view of the main part of the device.

FIG. 4 is an equivalent circuit diagram of a general active matrix type liquid crystal panel.

FIG. 5 is an enlarged view of a main part of a conventional liquid crystal display device.

FIG. 6 is a sectional view of the main part of the device.

[Explanation of symbols]

 16 (a) Second signal wiring 16 (b) Second scanning wiring 17 (a) First scanning wiring 17 (b) First signal wiring 18, 19, 24 Opening contact portion

Claims (3)

[Claims] 1. A liquid crystal is sealed on a pair of substrates, pixel electrodes arranged in a matrix on one substrate of the substrates, a thin film transistor formed adjacent to the pixel electrodes, and a thin film transistor of the thin film transistor. A signal wiring connected to a source electrode and a scanning wiring connected to a gate electrode of the thin film transistor are provided, and at least one of the signal wiring and the scanning wiring is a wiring of first and second layers. An insulating layer having an opening is provided between the first and second wirings, and the wirings of the first and second two layers maintain electrical contact through the opening. Liquid crystal display device that is arranged. 2. The scanning wiring or the signal wiring, the first wiring, the second wiring, either one is provided except for the intersection of the scanning wiring and the signal wiring.
The described liquid crystal display device. 3. The first signal wiring is simultaneously formed when forming the first scanning wiring, and the second scanning wiring is simultaneously formed when forming the second signal wiring. Item 3. A method for manufacturing a liquid crystal display device according to item 1 or 2.