JPH02250038A - Thin film transistor array - Google Patents

Abstract

PURPOSE:To make a closed area and a condenser area compatible by forming the part or the overall of an adjacent gate electrode with a transparent electrode and extending the gate electrode on the side of the transparent electrode which becomes an image element. CONSTITUTION:A thin film transistor 6 is formed on an insulating substrate 7 and the transparent electrode 1 for the image element is connected to an electrode on one side of the thin film transistor 6, that is, to a source electrode 6a. Since the adjacent gate electrode 3a is connected to a transparent conductive material 5 which is extended as far as nearby the thin film transistor 6, a condenser 2c which pinches a gate insulating film 8 with the transparent electrode 1 and the transparent conductive material 5 is formed. The condenser forms quite large capacity compared with a condenser pinched by the adjacent gate electrode 3a and the transparent electrode 1. Thus, condenser capacity can be increased without lowering a numerical aperture and electric charges written in the image element are readily held. Then, contrast is improved if the above thin film transistor array is used for a liquid crystal display device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electro-optical device such as a liquid crystal display device, which is applied to a wall-mounted television, a projector, etc.

[Summary of the invention]

The present invention provides a thin film transistor array in which a gate electrode and a drain electrode are provided between adjacent gate electrodes and the transparent electrode via the source electrode and the transparent electrode of the thin film transistor in a thin film transistor array arranged in a grid pattern. , in a capacitor whose purpose is to retain charge, the area of the capacitor is increased by using a transparent electrode material for part or all of the gate electrode portion and extending it toward the transparent electrode side.

[Conventional technology]

FIG. 4 is a sectional view of a thin film transistor array according to the prior art, and FIG. 5 is a sectional view of another thin film transistor array according to the prior art. The following description will be made based on these figures.

Conventionally, in electro-optical devices such as liquid crystal displays using thin film transistor arrays, transparent electrode portions 1 that become pixels have been used to achieve higher quality display, as shown in FIG.
and the common electrode 4, a capacitor 2a for charge retention is connected between the
The technology for providing this is well known. Furthermore, regarding the capacitor 2a, a technology has been developed in which a capacitor 2b is provided between the adjacent gate electrode 3 and transparent electrode 1, as shown in FIG. 5, with the aim of reducing costs and parasitic capacitance by saving masks. This greatly contributes to high-quality display.

[Problem that the invention seeks to solve]

However, in the conventional capacitors as described above, metal is used as the gate electrode material, and since it is opaque, attempting to increase the capacitor area will result in a reduction in the opening area. At most, it was possible to obtain a width equivalent to the width of the gate electrode. That is, it is impossible to achieve both the aperture area and the capacitor area, which limits the improvement of contrast in liquid crystal displays and the like.

[Means for solving problems]

As a means for solving the above-mentioned problems, in the present invention,
It was decided to form part or all of the adjacent gate electrodes with transparent electrodes and extend them toward the transparent electrodes that form pixels.

[Effect]

By using the measures according to the invention, larger capacitors can be formed without reducing the aperture area.

〔Example〕

FIG. 1 shows a sectional view of a first embodiment of the present invention.

In this figure, a thin film transistor 6 is placed on an insulating substrate 7.
A transparent electrode 1 serving as a pixel is connected to one electrode of the thin film transistor 6, that is, a source electrode 6a. Since the adjacent gate electrode 3a is connected to the transparent conductive material 5 extended to the vicinity of the thin film transistor 6, the transparent electrode 1 and the transparent conductive material 5
A capacitor 2C sandwiching the gate insulating film 8 is formed. This capacitor has a much larger capacitance than a conventional capacitor which is formed by sandwiching only the adjacent gate electrode 3a and the transparent electrode 1. Note that the adjacent gate electrode 3a is a so-called front-stage gate that is located on this side of the gate electrode 3 in the signal scanning direction.

FIG. 2 shows a cross-sectional view of a second embodiment of the present invention, in which the adjacent gate electrodes 3 in FIG. 1 are integrally formed of a transparent conductive material 5. . In this case, the number of masks can be reduced by one compared to the embodiment shown in FIG.

Furthermore, FIG. 3 is a plan view of the third embodiment, and unlike FIGS. 1 and 2, it is not necessary for the transparent conductive material 5 to cover all of the transparent electrodes 1 that form pixels; As shown, it is sufficient to extend the desired capacitance toward the transparent electrode 1 side.

〔Effect of the invention〕

As described above, according to the present invention, in a thin film transistor array having a capacitor, the capacitance of the capacitor can be increased without reducing the aperture ratio. When used in a display device, it contributes to improving contrast.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a first embodiment of the invention, FIG. 2 is a sectional view of a second embodiment of the invention, and FIG. 3 is a plan view of a third embodiment of the invention. FIG. 4 is a cross-sectional view of a thin film transistor array according to the prior art, and FIG. 5 is a cross-sectional view of another thin film transistor array according to the prior art. Transparent electrode Capacitor Adjacent gate electrode Common electrode Transparent conductive material Thin film transistor Insulating substrate Gate insulating film Applicant Seiko Electronics Co., Ltd. Representative Patent attorney Takayuki Hayashi Sukehonmaru O.
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Claims (1)

[Claims] A gate electrode and a drain electrode are arranged in a grid pattern, a thin film transistor is arranged at the intersection of the gate electrode and the drain electrode, and the source electrode of the thin film transistor is connected to the adjacent gate electrode through a transparent electrode. In a thin film transistor array having a capacitor provided between the capacitor and the capacitor, at least a part of the gate electrode of the capacitor is made of a transparent conductive material, and a part of the gate electrode is on the transparent electrode side. A thin film transistor array characterized by a protrusion.