JPH0682816A - Active matrix substrate - Google Patents

Abstract

PURPOSE:To provide the active matrix substrate which can be manufactured at low cost in a short process and is excellent in yield. CONSTITUTION:The active matrix substrate is equipped with gate bus lines 10 and source bus lines 20 which are formed crossing each other in a lattice shape, pixel electrodes 40 formed in areas surrounded with the gate bus lines 10 and source bus lines 20, and TFTs 30 which are electrically connected to the pixel electrodes 40, gate bus lines 10, and source bus lines 20. The gate bus lines 10 and pixel electrodes 40 are formed of the same material on the same insulating layer and conductive film pieces 12 are formed of the same material with the source bus lines 20 on the same insulating layer opposite the parts of the gate bus lines 10 except parts crossing the source bus lines 20. A part of the conductive film pieces 12 forms gate electrodes and the conductive film pieces 12 and gate bus lines 109 are connected via through holes.

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 for a display device, in which display pixel electrodes are arranged in a matrix for high density display, and more specifically, a switching element is provided on the display pixel electrodes. The present invention relates to an active matrix substrate that performs display by applying a drive signal via the.

[0002]

2. Description of the Related Art In a display device such as a liquid crystal display device, an EL display device and a plasma display device, a display pattern is formed on a screen by selecting and modulating the display pixels arranged in a matrix. ing. In this case, an active matrix driving method is known as a method of selecting display pixels and performing light modulation. Since this method enables high-contrast display, a liquid crystal television, a word processor, a computer terminal, etc. It has been put to practical use as a display.

This active matrix driving method is a method in which each picture element is arranged so as to be optically modulated by an independent picture element electrode, and a switching element is connected to each picture element electrode. As a switching element for selectively driving the pixel electrode, a TFT (thin film transistor) element, a MIM (metal-insulating film-metal) element, a MOS
Transistor elements, diodes, varistors, etc. are commonly used. Further, in the active matrix substrate, the respective pixel electrodes are arranged so that the counter electrodes face each other with the display medium such as liquid crystal, EL light emitting layer or plasma light emitter interposed therebetween. When the voltage applied to each picture element electrode is switched, the display medium interposed therebetween is optically modulated, and the modulation is visually recognized as a display pattern.

FIG. 7 shows a conventional example of an active matrix substrate. According to this, tantalum Ta is deposited on the insulating substrate.
A plurality of scanning wirings (gate bus lines) 71 formed by
0 and a plurality of signal wirings (source bus lines) 720 formed of titanium Ti are provided so as to be orthogonal to each other in a lattice shape with a gate insulating film interposed therebetween. A pixel electrode 740 made of ITO (indium oxide and tin oxide) is arranged in each rectangular region surrounded by each scanning line 710 and each signal line 720. TFTs 730 as switching elements are provided at the corners of each region. TFT here
Reference numeral 730 denotes each pixel electrode 740, and one scanning wiring 710 and one signal wiring 72 which are close to each pixel electrode 740.
0 and 0 are respectively electrically connected. Scanning wiring 71
A branch line 711 branches from 0 toward the pixel electrode 740, and a portion from the tip of the branch line 711 serves as a gate electrode of the TFT 730 as a switching element.

[0005]

By the way, since the scanning wirings, the signal wirings, and the picture element electrodes of such an active matrix substrate are formed in separate steps, the film forming process is required to form them. , Photolithography process, etching process, etc. are repeated. However, in each process, there is an unavoidable risk of producing substrate defects that lead to yield loss.
Also, the more processes, the higher the manufacturing cost.

The present invention solves the above problems, and an object of the present invention is to provide an active matrix substrate which can be manufactured in a shorter process at low cost and has a good yield.

[0007]

A first active matrix substrate of the present invention is surrounded by a plurality of scanning wirings and a plurality of signal wirings which are formed to intersect each other in a grid pattern and surrounded by the scanning wirings and the signal wirings. In an active matrix substrate having picture element electrodes formed in respective regions and switching elements electrically connected to the picture element electrodes, the scanning wirings, and the signal wirings, the scanning wirings and the picture elements are provided. The electrodes are formed of the same material on the same insulating layer, the signal wiring is formed on an insulating layer different from the insulating layer, and the signal wiring is formed on the same insulating layer of the same material. A conductive film piece is formed opposite to the scanning wiring portion excluding a portion intersecting with the signal wiring, a part of the conductive film piece forms a gate electrode, and the conductive film piece and the scanning wiring are further formed. Connected through a through hole The object can be achieved.

The second active matrix substrate of the present invention is formed in a plurality of scanning wirings and a plurality of signal wirings intersecting each other in a grid pattern, and in respective regions surrounded by the scanning wirings and the signal wirings. In the active matrix substrate, the pixel electrodes are formed on the insulating layer, and the switching elements electrically connected to the pixel electrodes, the scanning wirings, and the signal wirings are formed. The signal wiring is formed on an insulating layer different from the insulating layer, and the scanning wiring is formed on the same insulating layer as the picture element electrode by a first conductive film piece formed of the same material. A second conductive film piece formed of the same material on the same insulating layer as the signal wiring, the first conductive film piece including a portion that intersects with the signal wiring. The second conductive film piece is opposed to the second conductive film piece, and the first Conductive film piece and is electrically connected, further has a portion of the second conductive film pieces forming the gate electrode, the object is achieved.

[0009]

In the first active matrix substrate of the present invention, both the signal wiring and the conductive film piece are formed of the same material on the same insulating layer, and the scanning wiring and the pixel electrode are formed on the same insulating layer. The conductive film formed of the same transparent conductive film and partially having a gate electrode is electrically connected to the scanning wiring. Therefore, the signal wiring and the conductive film piece, and the scanning wiring and the pixel electrode can be manufactured in the same process. Further, in the second active matrix substrate of the present invention, the scanning wiring includes the first conductive film piece formed of the same transparent conductive film on the same insulating layer as the pixel electrode and the same insulating layer as the signal wiring. And a second conductive film piece formed of the same material on the top surface of the second conductive film piece, and the second conductive film piece having a gate electrode as a part thereof is conductive with the first conductive film piece. Therefore, the pixel electrode and the first conductive film piece, and the signal wiring and the second conductive film piece can be manufactured in the same process.

[0010]

【Example】

(Embodiment 1) FIG. 1 is a plan view showing a constitutional example of an active matrix substrate of the present embodiment, and FIG. 2 is AA ′ of FIG.
3 is a sectional view taken along line BB ′ of FIG. 1 and FIG. 3 is a sectional view taken along line BB ′ of FIG. 1.

This active matrix substrate has a source bus line 20 on an insulating layer such as a glass substrate 1.
And the gate bus line 10 are formed in this order in a grid pattern through the insulating film 50, and the pixel electrode 40 is formed on the same insulating film 50 as the gate bus line in the region surrounded by both bus lines 10 and 20. Has been done. A gate electrode 11 protruding toward the pixel electrode 40 is branched to the gate bus line 10, and a thin film transistor (hereinafter abbreviated as TFT) 30 as a switching element is formed in a portion from the tip of the gate electrode 11 to a branch. ing. Source bus line 2
A conductive film piece 12 is formed below the gate bus line 10 except the portion intersecting 0 with the insulating film 50 on the same substrate as the source bus line, and the gate bus line 10 and the conductive film piece 12 are separated from each other. It is electrically connected via a connecting portion 13 formed by etching the insulating film.

Next, the procedure for manufacturing this active matrix substrate will be described with reference to FIGS.

First, the source bus line 20 and the conductive film piece 12 are formed on the glass substrate 1 as follows.
That is, a low-resistance conductor is laminated on the glass substrate 1 by a sputtering method and then patterned to form the source bus line 20 and the conductive film piece 12. Before forming the source bus line 20 and the conductive film piece 12 on the surface of the glass substrate 1, a T film as a base coat film is formed.
It is also possible to form an insulating layer such as a ₂ O ₅ . Examples of the low-resistance conductor include Al, Mo, Ta, etc., but Ta was used in this example. Thus, the source bus line 20 and the conductive film piece 12 can be manufactured in the same process.

Next, the insulating film 50 is laminated on the source bus line 20 and the conductive film piece 12. In this embodiment, a silicon nitride film having a thickness of 3000 angstrom is laminated by the plasma CVD method to form an insulating film. At this time, the source bus line 20 may be anodized to have a structure that further enhances the insulating property.

Subsequently, the semiconductor layer 52 and the etching stopper layer 53 are laminated in this order by plasma CVD so as to overlap a part of the insulating film 50. The etching stopper layer 53 is then patterned. In this embodiment, the semiconductor layer 52 is an intrinsic semiconductor amorphous silicon layer, the etching stopper layer 53 is the same silicon nitride as the insulating film 50, and the film thickness is 600 angstroms and 2000 angstroms, respectively.

Next, a through hole for electrically connecting the gate bus line 10 to the insulating film 50 on the conductive film piece 12, a source bus line 20 and a source electrode 31 which will be formed in a later step. Through holes for electrical connection are formed through patterning and etching processes,
The connection parts 13 and 14 are used.

Subsequently, in order to improve the ohmic contact between the semiconductor layer 52 and the source electrode 31 or the drain electrode 32 formed in the subsequent step, the contact layer 60 is laminated by the plasma CVD method. In this embodiment, the contact layer 60 is an n ⁺ -type amorphous silicon layer doped with phosphorus and has a thickness of 600 Å. After that, the contact layer 60 and the semiconductor layer 52 are patterned.

Further, a transparent conductive film to be the gate bus line 10, the source electrode 31, the drain electrode 32, and the pixel electrode 40 is laminated on the insulating film 50 and the contact layer by a sputtering method, and is patterned. The gate bus line 20, the source electrode 31, the drain electrode 32, and the pixel electrode 40 are obtained. In this example, an ITO film was used as the transparent conductive film.

Further, a protective film layer 70 is laminated on the picture element. The protective film layer 70 may have a window structure in which a part of the central portion of the pixel electrode 40 is removed after the protective film layer 70 is laminated.

As shown in FIG. 3, the conductive film piece 12 is electrically connected to the gate bus line 10 via the connecting portion 13. According to this structure, the gate signal is applied to the gate bus line 10 and the conductive film piece 1 in the section where the conductive film piece 12 is present.
It will flow through both. As a result, in this section, even if a disconnection occurs in a part of the gate bus line 10, the signal is transmitted through the conductive film piece 12 before the disconnection portion, so that the disconnection does not extend to the entire gate bus line. It becomes possible to prevent it.

In the active matrix substrate of this embodiment, the source bus line 31 and the conductive film piece 12 are formed on the glass substrate 1, and the gate bus line 10 and the pixel electrode 32 are formed on the insulating film 50. However, the active matrix substrate of the present invention has the opposite structure, that is, the gate bus line 10 and the pixel electrode 32 are formed on the glass substrate 1, and the source bus line 3 is formed on the insulating film 50.
A structure in which 1 and the conductive film piece 12 are formed may be used.

(Embodiment 2) FIG. 4 is a plan view showing a structural example of an active matrix substrate of this embodiment. The gate bus line 110 includes a conductive film piece 115 formed of the same material on the same insulating film (not shown) as the pixel electrode 140,
The same glass substrate as the source bus line 120 (not shown)
It is composed of a conductive film piece 112 made of the same material.

In this embodiment, the conductive film piece 112 is formed of a low-resistance conductor together with the source bus line 120, as in the first embodiment. The conductive film piece 115 is formed of a transparent conductive film (ITO film) together with the pixel electrode 140.

In the active matrix substrate of this structure, the conductive film piece 11 that constitutes the gate bus line 110.
5 and the pixel electrode 140 are close to each other. As a result, the possibility that the gate bus line 110 and the pixel electrode 140 are short-circuited is reduced as compared with the first embodiment.

The active matrix substrate of the present invention has a structure opposite to that of this embodiment, that is, a conductive film piece 1 is formed on a glass substrate.
15 and a pixel electrode 32 are formed, and an insulating film (not shown)
A structure in which the source bus line 120 and the conductive film piece 112 are formed thereon may be used.

(Embodiment 3) FIG. 5 is a plan view showing a constitutional example of an active matrix substrate of the present embodiment, and FIG. 6 is a sectional view taken along the line CC 'in FIG.

In this embodiment, the gate bus line 2
10 is a conductive film piece 215 formed of the same material on the same insulating film (not shown) as the pixel electrode 240 as in the second embodiment.
And a conductive film piece 212 formed of the same material on the same glass substrate (not shown) as the source bus line 220, but a part of the pixel electrode 240 is a conductive film via an insulating film 250. The structure is superimposed on the piece 212. According to this structure, the conductive film piece 212 and the pixel electrode 204 are simultaneously formed.
Since the additional capacitance 241 can be formed between the active matrix substrate and a part thereof, the quality of the active matrix substrate can be improved.

[0028]

As is apparent from the above description, in the first active matrix substrate of the present invention, the signal wiring and the conductive film piece can be manufactured in the same process, and the scanning wiring and the pixel electrode can be manufactured. Can be manufactured in the same process. Further, in the second active matrix substrate of the present invention, the scanning wiring includes the first conductive film piece that can be manufactured in the same process as the pixel electrode and the second conductive film piece that can be manufactured in the same process as the signal wiring. Are formed from. As a result, it becomes possible to manufacture at a lower cost and in a shorter process than in the past, and it becomes possible to provide an active matrix substrate having a good yield.

Further, when the size of the active matrix substrate becomes large, the bus line becomes long accordingly, so that the line resistance becomes large, which may cause a problem of signal delay. However, the second active matrix substrate of the present invention. According to this, since the scanning wiring can be composed of the same transparent conductive film as the pixel electrode and the conductive film having a small specific resistance, the entire scanning wiring can be formed as compared with the case where the scanning wiring is formed only of the transparent conductive film. Line resistance can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing an active matrix substrate according to a first embodiment.

2 is a cross-sectional view taken along the line A-A 'in FIG.

3 is a cross-sectional view taken along line B-B ′ of FIG.

FIG. 4 is a plan view showing an active matrix substrate according to a second embodiment.

FIG. 5 is a plan view showing an active matrix substrate according to a third embodiment.

6 is a cross-sectional view taken along the line C-C ′ of FIG.

FIG. 7 is a sectional view showing a conventional example.

[Explanation of symbols]

1, 201 glass substrate 10, 110, 210, 710 gate bus line 20, 120, 220, 720 source bus line 11, 711 gate electrode 31 source electrode 32 drain electrode 40, 140, 240, 740 pixel electrode 12, 112, 115, 212, 215 conductive film pieces 13, 14, 113, 213, 214 connection parts 30, 130, 230, 730 TFTs 50, 250 gate insulating film 52 semiconductor layer 53 etching stopper layer 60 contact layer 70 protective film layer 241 additional capacitance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaya Okamoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Co., Ltd. Incorporated (72) Inventor Yu Kajitani 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (2)

[Claims] 1. A plurality of scanning wirings and a plurality of signal wirings formed to intersect in a grid pattern, a pixel electrode formed in each region surrounded by the scanning wirings and the signal wirings, and each picture. In an active matrix substrate including a switching element electrically connected to each element electrode, each scanning wiring, and each signal wiring, the scanning wiring and the pixel electrode are formed of the same material on the same insulating layer. The signal wiring is formed on an insulating layer different from the insulating layer, and scanning is performed on the different insulating layer made of the same material as the signal wiring except the portion intersecting with the signal wiring. An active matrix substrate in which a conductive film piece is formed facing a wiring portion, a part of the conductive film piece forms a gate electrode, and the conductive film piece and the scanning wiring are connected through a through hole. . 2. A plurality of scanning wirings and a plurality of signal wirings formed to intersect in a grid pattern, a pixel electrode formed in each region surrounded by the scanning wirings and the signal wirings, and each picture. In an active matrix substrate including element electrodes, scanning lines, and switching elements electrically connected to signal lines, the pixel electrodes are formed on an insulating layer, and the signal lines are formed on the insulating layer. Is formed on another insulating layer, and the scanning wiring is formed by a first conductive film piece made of the same material and the signal wiring on the insulating layer on which the pixel electrodes are formed. A second conductive film piece formed of the same material on another insulating layer, the second conductive film piece being formed with its both ends located inside two adjacent signal wirings; End portions of the second conductive film piece on both sides of the signal wiring between which the conductive film piece is located. It is formed so as to face it, and each of the both ends is connected to the second conductive film piece through a through hole, and a part of the second conductive film piece forms a gate electrode. Active matrix substrate.