JP2768590B2 - Active matrix substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix substrate in which picture element electrodes are arranged in a matrix and a switching element is connected to each picture element, and relates to a liquid crystal display element, an electroluminescence (EL) display element, and a plasma display element. It is useful as a substrate for such as.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device, an electroluminescence (EL) display device, a plasma display device and the like have a liquid crystal, an EL light emitting layer or a plasma light emitting material between a pair of substrates in which picture element electrodes are arranged in a matrix. The display pattern is formed on the screen by selecting the picture element electrode with a display medium such as.

An active matrix method is one of the methods for selecting a pixel electrode.

A display element of this type comprises a scanning line and a signal line wired in a matrix on a substrate, a picture element electrode arranged in a region surrounded by the scanning line and the signal line, An active matrix substrate including the signal lines and switching elements connected to the picture element electrodes is provided. A scanning signal is sent from the scanning line to operate the switching element, and a display signal is applied from a signal line in synchronization with the switching element to select and control a pixel electrode to optically display a display medium interposed therebetween. The display is performed by modulation. According to this active matrix system, high-contrast display is possible, and it has been put to practical use in liquid crystal televisions, word processors, computer terminal displays, and the like.

[0005] As a switching element for selectively driving a pixel electrode, a TFT (Thin Film Transistor) element, MI
M (metal-insulating-metal) elements, MOS transistor elements, diodes, varistors and the like are generally used,
Devices using TFT elements are considered to be promising in terms of display quality.

[0006]

However, in the active matrix substrate, a signal line for supplying a display signal to the picture element electrode may be disconnected during manufacturing due to some cause. Then, a display signal to be originally given is not inputted before the broken portion, and as a result, a line defect occurs on the display element. This significantly impairs the quality of the display element and results in a defective product.

In view of the above, various techniques for preventing disconnection of a signal line have been conventionally proposed. One example of such a technique is to increase the number of layers of the signal line. This is a method in which after forming a signal line, a conductive film for forming a pixel electrode is also formed on the signal line for disconnection redundancy. Even if the signal line is disconnected, the disconnection redundancy By forming a conductive film for use, electrical connection can be achieved.

However, in this method, a conductive film for forming a picture element electrode is formed between the picture element electrodes at the same time as the picture element electrodes. There is a problem in that the leakage method often occurs between the picture element electrode and the conductive film for disconnection redundancy.

When the signal electrode is formed simultaneously using the same conductive film as the picture element electrode, a disconnection redundant means must be separately provided.

It is an object of the present invention to further promote this concept, and particularly to prevent disconnection of signal lines with an accuracy of conventional formation without increasing the number of processes in an active matrix substrate using TFTs.

[0011]

In the active matrix substrate of the present invention, a scanning line, a signal line and a pixel electrode are arranged on an insulating substrate, and a switching element is provided on the scanning line, the signal line and the pixel electrode. In the active matrix substrate connected to the above, the disconnection redundant conductive film laminated on the signal line and the contact layer of the switching element are formed of a high-conductivity microcrystalline semiconductor.

In the active matrix substrate, the signal electrode is formed of the same conductive film as the picture element electrode.

[0013]

According to the above structure, even when the signal line is disconnected for some reason, the display signal is transmitted through the high-conductivity microcrystalline semiconductor to the portion after the disconnection.

In addition, since the high-conductivity microcrystalline semiconductor provided on one surface of the signal line can be formed at the same time when the contact layer of the switching element is formed, the number of processes is not increased. In addition, since the precision of forming the disconnection redundant conductive film at this time is only required to be accurate between the signal electrodes, there is no difficulty in the process.

Further, when the signal electrode is formed of the same conductive film as the picture element electrode, the process can be further simplified while having the disconnection redundant means.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of an active matrix substrate showing one embodiment of the present invention, FIG. 2A is a sectional view taken along line AA ′ of FIG.
FIG. 2B is a cross-sectional view taken along the line BB ′ of FIG. The scanning lines 2a and the signal lines 3a are arranged in a matrix on the insulating substrate 1, and the pixel electrodes 4 are arranged in a rectangular area surrounded by the scanning lines 2a and the signal lines 3a. The scanning line 2a and the signal line 3a are branched into a scanning electrode 2b and a signal electrode 3b that protrude toward the picture element electrode 4, and a TFT is formed as a switching element at the intersection of the scanning electrode 2b and the signal electrode 3b. . The TFT is connected to the pixel electrode 4 by the drain electrode 5. TFT as a switching element
As shown in FIG. 2B, an insulating film 6, a semiconductor layer 7, an etching stopper 8, and a high-conductivity microcrystalline semiconductor 9 are sequentially stacked on the scanning electrode 2b, and further, a signal electrode 3b and a drain electrode 5 are provided. The picture element electrode 4 is formed at one end of the drain electrode 5. The high-conductivity microcrystalline semiconductor 9 functions as a contact layer for improving the ohmic contact between the semiconductor layer 7 and the signal electrode 3b and the drain electrode 5. . The high-conductivity microcrystalline semiconductor 9 is also provided on the signal line 3a, and functions as a conductive film for disconnection redundancy of the signal line 3a.

Hereinafter, the active matrix substrate will be described in accordance with a process.

First, the scanning lines 2a and the scanning electrodes 2b are formed on the insulating substrate 1. In this embodiment, glass was employed as the insulating substrate 1. On the surface of the insulating substrate 1, an insulating film such as Ta ₂ O ₅ may be formed as a base film. A scanning line 2a and a scanning electrode 2b are obtained by laminating Al, Mo, Ta, or the like on the insulating substrate 1 by using a sputtering method, and then patterning it.

Next, an insulating film 6 is laminated thereon. In this embodiment, the SiNx film is formed to 3000
ÅLaminated to form an insulating film 6. Further, the insulating property of the scanning line 2a may be enhanced by anodic oxidation, and the insulating film 6 may be omitted.

Subsequently, a semiconductor layer 7 and an etching stopper 8 are formed continuously on the insulating film 6. Using a plasma CVD method, intrinsic semiconductor amorphous silicon (hereinafter referred to as “a-Si (i)”) as the semiconductor layer 7 and SiNx same as the insulating film 6 as the etching stopper 8 are laminated to a thickness of 600 ° and 2000 °, respectively. Then, each is patterned into a predetermined shape.

Subsequently, as a high-conductivity microcrystalline semiconductor 9,
N + type microcrystalline silicon film to which phosphorus is added (hereinafter referred to as “a
-Si (μc-n +) ”) with a thickness of 1000 ° by plasma CVD. This high-conductivity microcrystalline semiconductor 9 is formed on the signal electrode 3 b and the drain electrode 5 and on the signal line 3.
a and a conductive film for disconnection redundancy of the contact layer and the signal line 3a. This a-Si (μc-n +) has a conductivity of 10 ³ times or more as compared with the conventional n + layer, and not only becomes a contact layer, but also becomes redundant when the signal line 3a is disconnected. This a-Si
Through the (μc-n +) layer, it is possible to transmit a signal even after the disconnection portion.

At this time, the high conductivity microcrystalline semiconductor 9
Since there is no problem in the process because the formation accuracy of the semiconductor device need only be the accuracy between the signal electrodes.

Next, a metal layer made of Ti, Al, Cr, Mo, or the like is formed as a conductive film on the entire surface of the substrate by a sputtering method, and is patterned to form a signal line 3a,
The signal electrode 3b and the drain electrode 5 were formed. In this example, T
i was used.

Next, a pixel electrode 4 is obtained by laminating ITO by a sputtering method and patterning it. At this time, as shown in FIG. 3, a structure in which the ITO 10 is left on the signal line 3a as in the conventional example may be adopted.

Further, a protective film (not shown) is laminated thereon. Note that the protective film may have a windowed structure for removing the central portion of the pixel electrode 4.

FIG. 4 is a front view of another embodiment of the present invention. Here, the high-conductivity microcrystalline semiconductor a-S is formed under the signal line except for the portion where the signal line 3a intersects the scanning line 2a.
i (μc−n +) 9 is present. By doing so, the step of the scanning line 2a can be reduced and the signal line 3a can be reduced.
The probability of disconnection of a is reduced.

FIG. 5 is a front view of another embodiment of the present invention. Here, the high-conductivity microcrystalline semiconductor a-Si (μc) is formed so as to cover a portion where the signal line 3a intersects with the scanning line 2a.
−n +) 9. Since this portion is most likely to be disconnected, providing this structure is effective in preventing disconnection.

FIGS. 6 and 7 are a front view and a sectional view taken along the line CC 'of another embodiment of the present invention. Here, signal line 3
a, the signal electrode 3b and the drain electrode 5 are formed of a conductive film of ITO forming the picture element electrode 4, and the process of forming the signal line 3a, the signal electrode 3b and the drain electrode 5 made of metal is further omitted. I have.

In this embodiment, the high-conductivity microcrystalline semiconductor 9 is arranged below the signal line 3a. However, the structure of the active matrix substrate in which the signal line 3a is formed before the high-conductivity microcrystalline semiconductor 9 is formed. In this case, the high-conductivity microcrystalline semiconductor 9 may be arranged above the signal line 3a.

[0030]

According to the present invention, even when a signal line is disconnected for some reason, a display signal is transmitted to a portion after the disconnected portion through a high-conductivity microcrystalline semiconductor which is a conductive film for disconnection redundancy. Therefore, the defect rate of the product can be reduced.

Since the disconnection redundant conductive film laminated on the signal line can be formed at the same time as the formation of the contact layer, the number of processes is not increased, and the cost can be suppressed. In addition, since the formation accuracy of the disconnection redundant conductive film at this time is only required to be accurate between the signal electrodes, there is no difficulty in the process.

When the signal electrode is formed of the same conductive film as the picture element electrode, the process can be further simplified while having the disconnection redundancy means.

[Brief description of the drawings]

FIG. 1 is a front view of an active matrix substrate showing one embodiment of the present invention.

FIG. 2 is an AA ′ sectional view (a) and a BB ′ sectional view (b) of the same.

FIG. 3 is a front view of an active matrix substrate showing another embodiment of the present invention.

FIG. 4 is a front view of an active matrix substrate showing another embodiment of the present invention.

FIG. 5 is a front view of an active matrix substrate showing another embodiment of the present invention.

FIG. 6 is a front view of an active matrix substrate showing another embodiment of the present invention.

FIG. 7 is a sectional view taken along the line C-C 'of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2a Scanning line 3a Signal line 4 Pixel electrode 9 High conductivity microcrystalline semiconductor

──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshiharu Kataoka, 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation In-company (72) Inventor Makoto Miyago 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-2-47633 (JP, A) JP-A-3-108767 (JP, A (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/136 500

Claims (2)

(57) [Claims] An active matrix substrate having a scanning line, a signal line, and a pixel electrode disposed on an insulating substrate, and a switching element connected to the scanning line, the signal line, and the pixel electrode; An active matrix substrate comprising: a disconnection redundant conductive film laminated on a line; and a contact layer of the switching element, formed of a high-conductivity microcrystalline semiconductor. 2. The active matrix substrate according to claim 1, wherein said signal electrode is formed of the same conductive film as said picture element electrode.