JPS61151516A - Substrate for mis type active matrix display device - Google Patents

Abstract

PURPOSE:To obtain the substrate suitable for use to the MIS type active matrix display device having a large numerical aperture and charge holding capacity and a good image display, without particularly increasing a man-hour, by applying a gate electrode composed of a transparent conductive film to said substrate. CONSTITUTION:The gate electrode 2 composed of the transparent conductive film of ITO etc. is provided on the transparent insulating substrate 1 such as a glass etc. and lies in an extended state thereon as a line type electrode. The gate insulating film 3 such as silicon dioxide and silicon nitrite, and a semiconductor film 5 such as an amorphous silicon are formed on the gate electrode 2. An insulating film 8 and the insulating film 3 are formed on a forward gate electrode 2<1>. The charge holding capacity is constituted from a part of an image electrode 4 which is the transparent conductive film such as ITO. By constituting an unit image as mentioned above, as the charge holding capacity part composed of the forward gate electrode 2<1> and the image electrode 4 transmits a light, the numerical aperture becomes large. A width of the gate electrode enlarges, thereby spreading an area which overlaps with the image electrode 4 and also enabling to enlarge the charge holding capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film transistor substrate in an active matrix liquid crystal display device.

[Conventional technology]

An example of a unit pixel of a conventional active matrix liquid crystal display device is shown in FIG. (
6).

(c) is connected to the D-DI line (see Figure 2) and -El
It is a sectional view of the box along the line. On a transparent insulating substrate 1 made of glass or the like, gate electrodes 2 which also serve as light shielding films such as Of, Ag10f, MQ2, AI, etc. are provided and extend as n1 row electrodes. The preceding gate electrode 2' is also shown. On the gate electrode 2, there is a gate insulating film a made of silicon dioxide, silicon oxide, etc., and a semiconductor M5 made of amorphous silicon, etc.
N1 semiconductor film 5 provided with a film thickness of about 000A to 5000μ
A drain electrode 6 and a source electrode 7 as column electrodes are arranged on the top, and the source electrode 7 and the pixel electrode 4 are connected.

A charge holding capacitor for holding image signals, etc. is composed of the gate electrode 21 at the previous stage, the insulating film 8, and the pixel electrode 4. Furthermore, a light shielding film, a passivation film, etc. are formed to pass light from above, but these are omitted as they are not directly related to the present invention. As described above, the method of forming a charge holding capacitor between the gate electrode wiring 21 of the other row and the pixel electrode 4 that connects light has the disadvantage that the effective pixel area for display, that is, the aperture ratio is reduced. In addition, in order to increase the porosity, a method that does not form a charge retention capacitor may be considered, but
In order to obtain a good image, the capacitance of the liquid crystal is voltage-dependent, and the image signal is distorted due to parasitic capacitance, etc., causing image deterioration. requires a charge retention capacitor, and the larger the capacitor, the better.

[Problem that the invention seeks to solve]

As can be seen from the examples in Fig. 2b>, G[+), and (C), in the past, good image quality could not be obtained unless the aperture ratio was small and the charge retention capacity was large. SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate for an active matrix liquid crystal display device that has a large porosity, a large charge holding capacity, and a good image display without particularly increasing the number of man-hours.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention forms the gate electrode with a transparent conductive film, and has a structure in which the charge holding capacitor section composed of the gate electrode and the pixel electrode transmits light. In addition,
The semiconductor film has a thickness that is not easily affected by light (for example, 100
0A or less].

[Effect]

With the above configuration, the charge retention capacitor portion formed by the gate electrode and the pixel electrode transmits light, so the aperture ratio increases, and the gate electrode can be enlarged to increase the charge retention capacitance. [Embodiment] An embodiment of the present invention will be described below based on the drawings. 1st
FIGS. 6), 6) and 6(G) show examples of the structure of the unit pixel of the present invention. ) and ω) in FIG. 1 are cross-sectional views taken along lines A1 and B- and Bl in FIG. On a transparent insulating substrate 1 made of glass or the like, gate electrodes 2 made of a transparent conductive film such as Toxic oxide are provided and extend as n1 row electrodes. The preceding gate electrode 2' is also shown. On the gate electrode 2, there is a gate insulating film 8 made of silicon dioxide, silicon nitride, etc., and a semiconductor film 5 made of amorphous silicon etc.
is formed. Note that the film thickness of amorphous silicon is a film thickness that is not easily affected by light (for example, 100 OA or less).
It is formed in n. On the gate electrode 2I in the previous stage, a rL9Hk film 8 is formed simultaneously with the gate insulating film 8, and is combined with a part of the pixel electrode 4, which is a transparent conductive film such as 3% toner, to form a charge retention capacitor. is composed of n. A drain electrode 6 and a source electrode 7 as column electrodes are arranged on the semiconductor film 5, and the source electrode 7 and the pixel electrode 4 are connected. If a unit pixel has such a structure, in which a buffer/film etc. may also be formed, the charge holding capacitor formed by the gate electrode 21 and the pixel electrode 4 in the previous stage will transmit light, so it will not open. The porosity is large. Furthermore, as shown in FIG. 1 (6), the width of the gate electrode is increased to increase the overlap with the pixel electrode 4, thereby making it possible to form a large charge holding capacitor. tx FIG. 8 et al.) show another planar structure example of the present invention in which the gate electrode wiring portion 9 is widened to prevent gate line disconnection. ) in FIG. 8 is to reduce the intersection of the line end of the gate line 2' of the charge holding capacitor section and the pixel electrode 4 as much as possible to prevent breakdown voltage failure. An example of the planar structure is shown below. Note that in FIG. 8(d), (6), the semiconductor film, source, drain electrodes, etc. are not shown.

〔Effect of the invention〕

As explained above, the present invention makes it possible to obtain a unit pixel with a sufficiently large charge holding capacity and a large aperture ratio, and has a bright, good image quality with good contrast, and is low cost. The present invention can provide a thin film transistor substrate for an MIS active matrix display device.

[Brief explanation of the drawing]

Figure 1 @ is a plan view showing an example of a unit pixel structure according to the present invention, and Figure 1 (6) and (c) are the same as Figure 1 (
B) It is a sectional view taken along the A-AI line and the B-Bl line. Figure 2 @ is a plan view of an example of a conventional unit pixel structure.
), C) are cross-sectional views taken along the lines (m+7) and m-z in FIG. 2 (m+7) and m-z. FIG. 3 shows a plan view of an embodiment of the invention. 10. Substrate, 2.2', Gate electrode, 8°. Insulating film, 411 pixel electrode, 59. Semiconductor film, 6°, drain electrode, 71. source electrode, 80. Insulating film, 90. Wiring Department and above Applicant Seiko Electronic Industries Co., Ltd. Agent Patent Attorney Mogami Affairs Figure 1 Cb) 1st (C) Figure 2 (b) Figure 2 (C) 41i erroneous a, S Figure 3 (b) )

Claims (1)

[Claims] In a substrate for an MIS type active matrix display device, in which at least a charge retention capacitor section is constituted by a preceding gate electrode, an insulating film, and a part of a pixel electrode made of a transparent conductive film, the gate electrode is formed of a transparent conductive film. A substrate for an MIS type active matrix display device, characterized in that it is formed of.