JPH05289101A - Thin-film transistor substrate - Google Patents

Abstract

PURPOSE:To minimize the degradation in image quality by a defect and to prevent the degradation in the display quality providing a slit in the pixel electrode part near a lower electrode and shielding the slit with an opaque thin film. CONSTITUTION:The slit 9 is provided in the pixel electrode part 7 near the lower electrode 8 for a storage capacity and the opaque thin film 10th shape of which is formed making the slit part 9 as its hollow part, is provided in one layer of interlayer insulating films. Then, the easy cutting of the desired pixel electrode 7 with a min. area is made possible without unnecessary damage of the transparent electrode which is hardly visibly recognizable. In addition the opaque hollow thin film can minimize the quantity of the light leakage from the slit part 9 generated by driving of a liquid crystal. White dot defects are, therefore, drastically decreased on the entire black display screen and the high image quality is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor substrate having a storage capacitor and having a large number of two-dimensionally arranged in an array, and particularly, a liquid crystal having a high quality by reducing an interlayer short circuit defect of the storage capacitor portion. The present invention relates to a thin film transistor substrate capable of providing a panel with a high manufacturing yield.

[0002]

2. Description of the Related Art Conventionally, as shown in a schematic plan view of FIG. 3 and a schematic sectional view of FIG. 4, a thin film transistor substrate of this type has a film of ITO, chromium or the like adhered to a desired shape on a glass substrate 1. Then, the gate electrode 2 is formed and the lower electrode 8 for the storage capacitor is also formed. Next, an interlayer insulating film 3 of silicon dioxide, silicon nitride or the like is deposited and formed to a desired thickness as a gate insulating film and an insulating film for a storage capacitor, and thereafter, amorphous silicon 4 or polycrystalline silicon which functions as an active element is formed. Further, a thin film of silicon (not shown) containing high concentration phosphorus or boron for obtaining ohmic contact with the electrodes of the drain 5 and the source 6 formed in the next step is attached in a desired shape to form the thin film transistor part. Form.

The metal material for the drain electrode and the source electrode of the thin film transistor section is generally a good conductor and is composed of a sputtered film such as opaque chromium or aluminum, and the pixel electrode 7 for displaying liquid crystal is, for example, the source electrode 6. It is composed of an electrically connected sputtered ITO film and a transparent electrode such as tin oxide. The region of the interlayer insulating film 3 narrowed in the laminated region of the pixel electrode 7 and the storage capacitor lower electrode 8 functions as a storage capacitor, and charges transferred from the drain electrode to the source electrode by the operation of the thin film transistor are stored in the pixel electrode for a long time. Load function to save to.

[0004]

In the conventional thin film transistor substrate described above, the lower electrode 8 and the pixel electrode 7 are easily electrically short-circuited when, for example, there is a defect in the interlayer insulating film in the storage capacitor forming region. However, the charge written from the drain electrode to the pixel electrode via the source electrode is easily lost from the pixel electrode portion. Therefore, when a liquid crystal is driven using a thin film transistor substrate having these defects, for example, when a "black" screen is displayed on the entire panel in a so-called normal white mode, the defect storage capacitor section is provided. The portion corresponding to the thin film transistor displayed a "white" screen, and the image quality of the liquid crystal panel was significantly deteriorated. These deteriorations in image quality have been a problem that must be avoided in the case of liquid crystal panels that directly appeal to human vision.

Moreover, the insulating film is generally made of a transparent material together with the lower electrode and the pixel electrode, and even if it is electrically confirmed that there is a defect in the storage capacitor portion of a particular thin film transistor, the transparent material is used. It is difficult to confirm the defective portion of the lower electrode of the lower layer and to identify the defective portion of the insulating film because of the property.

[0006]

A thin film transistor substrate according to the present invention is provided with a slit in a pixel electrode portion near a lower electrode for a storage capacitor, and further, an opaque thin film is formed as a lower layer of an interlayer insulating film in a shape in which the slit portion is hollow. In order to reduce the influence of short circuit failure, the pixel electrode narrowed by this slit is cut when the lower part that provides the storage capacitance and the pixel electrode are electrically short-circuited due to a defect such as an insulating film. Is.

[0007]

In the vicinity of the storage capacitor portion including the transparent insulating film laminated on the transparent lower electrode and the transparent pixel electrode portion, the pixel electrode arranged in the uppermost layer has the highest visibility. Therefore, by arranging the slit portion of the pixel electrode in the vicinity of the position corresponding to the lower electrode of the lower layer having low visibility, it becomes possible to easily estimate the existing position of the lower electrode. Therefore, by cutting the slit provided in the pixel electrode, the pixel electrode and the lower electrode can be electrically separated without damaging the lower electrode. This is nothing but repairing an electrical short between the lower electrode and the pixel electrode. Since the thin film transistor repaired in this way loses the storage capacity, the charge retention time on the pixel electrode is reduced to about half that of the normal part, but a gray-black display is displayed on the all-black display surface of the liquid crystal panel. In addition, the deterioration of the image quality due to the defect is suppressed to the minimum. Moreover, the slit is generally a region where light is transmitted without the liquid crystal being oriented, but since most of this region is shielded by an opaque thin film with a hollow, leakage light is minimized and display quality is degraded. Can be prevented.

[0008]

The present invention will be described below with reference to the drawings. FIG. 1 is a plan view of the first embodiment of the present invention. Chromium having a thickness of 1000 Å is deposited and formed in a desired shape as the lower electrode 8 and the lower electrode bus line 8 ′ for the storage capacitor, and then 2,000 Å of chromium is desired as the gate electrode 2 and the gate electrode bus line 2 ′. It adheres to the shape of. At this time, at the same time, the opaque region 10 having a hollow portion for shielding light is formed. Thereafter, a silicon dioxide film having a thickness of 2000 angstrom and a thickness of 50 is used as a gate insulating film and an interlayer insulating film.
00 angstrom of silicon nitride is laminated and deposited in a desired shape (not shown). In the active element region, an amorphous silicon thin film 4 having a thickness of 5000 angstrom, and a thickness of 100 containing phosphorus for contacting the drain electrode and the source electrode formed in the next step.
A silicon thin film (not shown) having a thickness of 0 angstrom is attached to form a desired shape. Next, the drain electrode 5, the drain electrode bus line 5 ', and the source electrode 6 have a thickness of 2
A chrome thin film having a thickness of 000 angstroms is deposited in a desired shape, and an ITO film having a thickness of 1000 angstrom having a slit 9 having a width of 10 μm is partially laminated with a source electrode to be deposited in a desired shape to form a pixel electrode 7. Constitute.

Now, referring to FIG. 1, the lower electrode 8 of the storage capacitor portion is shown.
When the pixel electrode 7 and the pixel electrode 7 are short-circuited between layers, the pixel electrode is cut by the laser light in the slit portion. By this operation, the interlayer short circuit defect between the pixel electrode 7 and the lower electrode 8 is repaired.

FIG. 2 is a plan view showing a second embodiment of the present invention. In the present embodiment, the slit 9 provided in the pixel electrode 7 is provided at one location, and accordingly, the shape of the opaque thin film 10 is not hollow but thin. Also in the case of this embodiment, the same effect as that of the first embodiment is exhibited. Therefore, the shape of the opaque thin film is not particularly limited.

In the above embodiment, the reverse stagger type thin film transistor is described as an example, but the present invention can be naturally applied to the forward stagger type thin film transistor. Furthermore, when the pixel electrode cutting of the slit portion of the present invention is carried out in a panel filled with liquid crystal, the amount of the pixel electrode material mixed in the liquid crystal due to cutting is small, and the physical characteristics of the liquid crystal The effect of minimizing the deterioration also appears.

[0012]

As described above, according to the present invention, a slit is provided in the transparent pixel electrode portion in the vicinity of the transparent storage capacitor lower electrode, and the pixel electrode in this slit portion to be cut later is hollow. Since the opaque thin film is arranged together, the desired pixel electrode can be easily cut in the minimum area without unnecessarily damaging the transparent electrode which is difficult to see. Moreover, the opaque hollow thin film can minimize the amount of light leakage from the slit portion caused by driving the liquid crystal. Therefore, the liquid crystal panel using the thin film transistor substrate of the present invention has the effect of significantly reducing white spot defects in an all black display screen and providing high image quality.

[Brief description of drawings]

FIG. 1 is a plan view of a thin film transistor substrate showing a first embodiment of the present invention.

FIG. 2 is a plan view of a thin film transistor substrate showing a second embodiment of the present invention.

FIG. 3 is a plan view showing a conventional thin film transistor substrate.

FIG. 4 is a cross-sectional view taken along the line AA ′ of FIG.

[Explanation of symbols]

 2 gate electrode 2'gate electrode bus line 3 insulating film 4 amorphous silicon 5 drain electrode 5'drain electrode bus line 6 source electrode 7 pixel electrode 8 lower electrode 8'lower electrode bus line 9 slit 10 opaque thin film

Claims (1)

[Claims] 1. A lower electrode for a storage capacitor, a gate electrode,
In a thin film transistor substrate having an interlayer insulating film, an amorphous silicon layer, source and drain electrodes, and a pixel electrode connected to the source electrode, a slit is provided in a pixel electrode portion near the lower electrode, and a slit is provided. A thin film transistor substrate, characterized in that at least a part thereof is optically shielded by an opaque thin film.