JP3054491B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device,
In particular, the present invention relates to a liquid crystal display device that prevents display defects due to electrostatic discharge generated at terminal edges.

[0002]

2. Description of the Related Art The screen of a liquid crystal display becomes large,
As the number of pixels increases, the yield decreases due to an increase in defects. As a countermeasure for this, there is a adoption of a redundant structure. For example, as an example, a flat display 1991, page 105, published by Nikkei BP, describes a redundant configuration that must be used.

For example, for one pixel (for example, one cell in which a switching element and a display electrode are a set), one more pixel is provided.
There is a type in which two TFTs are provided to prevent a point defect due to a TFT failure, or a type in which a spare line is provided, and when a line is broken, the disconnection is relieved through the spare line. In addition, as described below as the theme of the present invention, static electricity held by an operator or a manufacturing apparatus is easily provided at a terminal edge, and is particularly provided on the outermost side of a group of pixels arranged in a matrix. The defective pixel causes display failure due to the electrostatic discharge. For this purpose, dummy pixels are further provided on the outermost side.

FIG. 4 is a schematic view thereof, and a gate line (2) integrated with a gate formed on a glass substrate (1) extends alternately in the vertical direction. Also, alternately extending in the horizontal direction is a drain line (3) extending from the drain of the TFT over the gate insulating film. The gate line (2) and the drain line (3) have a gate terminal (4) and a drain terminal (5), respectively, and their surfaces are exposed to connect, for example, TAB.

[0005] Further, the dummy pixel (6) is arranged at the outermost part of the pixel area of FIG. 4 and is a dummy pixel (6). Can be protected. Here, a long terminal and a slightly short terminal are provided. The longer terminal is an original terminal, and the shorter terminal is provided for the purpose of line inspection.

[0006]

As described above, in the manufacturing process, electrostatic discharge is inevitably generated at the corners of the insulating substrate (1), and in particular, one of the gate terminal groups provided above or below is provided. It is likely to occur at the leftmost or rightmost gate terminal and the topmost or lowermost drain terminal of the right or left drain terminal group. As described above, it is only necessary to protect with the dummy pixel, but it is not possible to protect with the dummy pixel alone.
Even if T is not destroyed, there is a problem that the threshold voltage V _TH shifts and a line defect occurs.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a first aspect is to provide a method in which a transparent insulating substrate is provided between an outermost address terminal and a data terminal in contact with a corner of the substrate. This problem can be solved by providing a surge absorbing capacitor using an insulating film as a dielectric layer, which is one configuration of the switching element.

Second, a first terminal formed in the same process as the gate terminal is provided outside the gate terminal group electrically connected to the gate line, and the drain terminal group electrically connected to the drain line is provided. A second terminal formed in the same process as the drain terminal is provided outside the device, the first terminal is integrally formed with a line formed in the same process as the gate line and serves as a lower electrode of a capacitor, and the second terminal is An upper electrode of a capacitor integrally with a line formed in the same process as the drain line,
The problem is solved by absorbing the surge with the capacitance composed of the upper electrode and the lower electrode.

[0009]

The switching element, for example, TFT or MIM,
An insulating film is provided as a configuration. In a reverse staggered transistor using a-Si or p-Si, a gate insulating film is used. In a staggered transistor using p-Si, an insulating film provided between a gate electrode and a source electrode is used as a dielectric of a capacitor. It can be configured as a body layer, and a capacitor can be provided between the outermost address terminal and the data terminal in contact with the corner. Therefore, by providing a capacitor at the corner where the electrostatic discharge is most likely to occur, the static electricity can be absorbed through the capacitor without flowing to the pixel area.
Therefore, line defects can be prevented.

Second, an inverted stagger type TFT has a gate insulating film provided between a gate electrode and a semiconductor layer. Therefore, in the same step as the gate electrode or the gate line provided under the gate insulating film, the lower electrode of the capacitor for electrostatic absorption is provided, and in the same step as the drain electrode or the drain line provided above the gate insulating film, An upper electrode of the capacitor is provided. The upper and lower electrodes are electrically insulated from the drain line and the gate line, and the upper and lower electrodes are connected to the outermost terminals of the corners (for example, the uppermost drain terminal on the left side in FIG. Electrical connection with the leftmost gate terminal on the side)
A capacitor for absorbing static electricity can be provided at the corner where discharge is most likely. Therefore, by providing a capacitor at the corner where the electrostatic discharge is most likely to occur, the static electricity can be absorbed through the capacitor without flowing to the pixel area.
Therefore, line defects can be prevented.

[0011]

Embodiments of the present invention will be described below. The present invention is effective for, for example, an active matrix type liquid crystal display device. The reason is that the TFT and the MIM each have an insulating layer as one component, and an electrode material is provided below and above the insulating layer. If this step is used, a capacitor for electrostatic absorption can be used without increasing the number of steps. Can be provided. Naturally, a simple matrix type liquid crystal display device is also possible, but in this case, the number of steps is increased because the configuration is smaller than that of the active matrix type. Basically, one substrate has a plurality of parallel first line groups, and the other substrate has only a plurality of parallel second line groups intersecting the first line. Therefore, it may be provided on either substrate, but if the line group is the upper or lower electrode of the capacitor, the number of steps must be increased for the remaining configuration.

As described above, each of them has a schematic configuration as shown in FIG. Before describing the details of the inverted staggered transistor using a-Si,
A liquid crystal display device employing a staggered transistor of -Si and an MIM will be described. Generally, as shown in FIG. 6, a staggered transistor employing p-Si has p-Si (1) serving as a semiconductor layer on a transparent insulating substrate (10).
1) is provided, on which a first insulating film (12) is covered. On top of this, a gate made of p-Si (13)
And a second insulating film (14) covering the gate.
Is provided. In the second insulating film, contact holes are provided in regions corresponding to the source and drain regions, and a source electrode (16) and a drain electrode (17) electrically connected to the display electrode (15) are provided. I have. Here, the lower layer electrode is formed in the same process as the gate electrode in FIG.
And a second insulating film is provided as a dielectric layer of the capacitor, and an upper layer electrode provided in the same step as the source or drain electrode is provided at the corner.

Next, a representative example of the MIM structure will be described with reference to FIG. On a transparent insulating substrate (20), a Ta electrode (21) and a display electrode (22) made of a transparent electrode material.
Is provided. On the surface of the Ta electrode (21), an insulating film (23) made of, for example, Ta ₂ O ₃ formed by anodic oxidation is provided.
4) is extended to the display electrode (22). Therefore, the lower electrode of the capacitor can be achieved in the same process as the Ta electrode (21), and the Cr electrode (24) can be achieved as the upper electrode via the insulating film (23). Therefore, a capacitor for absorbing static electricity can be formed at the corner without increasing the number of steps.

Next, a liquid crystal display device employing an inverted staggered a-Si transistor will be specifically described with reference to FIG. First, a gate (31) formed on a transparent insulating substrate (30) and this gate (3
Plural gate lines (32) formed integrally with 1)
A storage capacitor electrode (33) formed apart from the gate line (32), and a storage capacitor line (34) formed integrally with the storage capacitor electrode; ) Formed on the entire surface of the gate insulating film (3)
5). In particular, the auxiliary capacitance is omitted in FIG.

[0015] The transparent insulating substrate (30) is made of, for example, glass. On this glass substrate (30), as shown in FIG. 5, a gate line (32) integral with the gate (31) extends vertically in parallel, and the gate (31) is formed of a gate line (32). The gate line (3
It may be formed as a part of 2). An auxiliary capacitance electrode (33) and an auxiliary capacitance line (34) formed integrally with the electrode also extend in parallel with the gate line (32). These electrodes are made of, for example, Cr or Al material,
a, Ta-Mo, Cr-Cu or the like may be used. Here, since the gate line and the auxiliary capacitance line are formed in the same process, the gate line (32) and the auxiliary capacitance line (34)
Is formed of, for example, about 1500 ° Cr. The first gate insulating film (35) covering the gate (31), the gate line (32), the auxiliary capacitance electrode (33) and the auxiliary capacitance line (34) is a SiNx film of about 3000 ° formed by plasma CVD. It is. Here, SiNx
Instead of a film, an SiO ₂ film may be used, or the two films may be formed as two layers. When the SiNx film or the SiO ₂ film is used alone, the film forming process may be divided into two processes to form a two-layer structure. In particular, in the case of a two-layer structure, the upper layer is extended on a display electrode described later.

Next, a display electrode (36) made of ITO is provided, and a non-doped first non-single-crystal silicon layer (37) is sequentially stacked on the active region of the TFT forming a gate (31). , A semiconductor protective film (38), and N ⁺
A second non-single crystalline silicon layer doped with a mold (39)
A source electrode (40) electrically connected to the second non-single-crystal silicon layer (39) corresponding to the source region and the display electrode (36); and a second non-single-crystal corresponding to the drain region. There is a drain line (42) extending integrally with the drain electrode (41) electrically connected to the silicon layer (39).

The first gate insulating film (3
5) On top of this, a non-doped amorphous silicon active layer (a-Si layer) (37) and an N ⁺ type amorphous silicon contact layer (N ⁺ a-Si layer) (39) are laminated to correspond to the channel. A semiconductor protective film (38) made of SiNx is provided between the a-Si layer (37) and the N ⁺ a-Si layer (39). The drain electrode (41) is integrated with the drain line, and the source electrode (4
0) is in contact with the display electrode (36), and both are formed of the same material. Here, for example, MO, Al
Are laminated. When the gate insulating film extends on the display electrode (36), a contact hole is formed and connected through this.

Although not shown below, a passivation film is provided (or may be omitted) on the upper layer.
For example, an alignment film made of polyimide or the like is provided.
On the other hand, an opposing glass substrate paired with the glass substrate (30) is provided. On the opposing glass substrate, a light-shielding film is provided at a position corresponding to the TFT, and an opposing electrode is provided. Further, the above-mentioned alignment film is provided.

Further, a spacer is provided between the pair of glass substrates, the periphery is sealed with a sealing material, and liquid crystal is injected from an injection hole to obtain the present device. Here, a-Si is used as the semiconductor layer, but p-Si may be used instead. A feature of the present invention is that a capacitor is provided at a corner of a transparent insulating substrate (30) as shown in FIG. FIG. 1 shows this specific structure (the upper left corner is enlarged). A region indicated by a chain line at the lower right of FIG. 1 is a display region.

A line extending upward from the display area is a gate line (32).
2) and the gate terminal (50) are electrically connected.
As can be seen from FIG. 8, the gate line is provided in the lower layer of the gate insulating film (35). Therefore, it is necessary to provide, for example, a through-hole that passes through to the upper layer at the mark x shown in FIG.
FIG. 3 shows this cross section, and shows the gate terminal (5
0) is provided on the gate insulating film (35). A first terminal (51) provided next to the leftmost gate terminal;
Has the same configuration as the gate terminal, and has a first terminal and a gate terminal, and a gate line (32) and a first line (52).
Are formed in the same process. Further, the first line (52) becomes a lower electrode (53) of a capacitor for absorbing surge in a non-display area (a corner where no terminal or line is provided).

A line extending leftward from the display area is a drain line (42).
2) and the drain terminal (54) are electrically connected. As can be seen from FIG. 8, the drain line is in the upper layer of the gate insulating film (35), so that the through-holes marked with “X” shown in FIG. 1 are unnecessary. FIG. 2 shows this cross section, and the drain terminal (54) has a gate insulating film (3).
5) Provided above. A second terminal (55) provided next to the uppermost gate terminal has the same configuration as the drain terminal, and includes a second terminal and a drain terminal, and a drain line (42) and a second line ( 56) are formed in the same step. The second line (56) becomes the upper electrode (57) of the surge absorbing capacitor in the non-display area (the corner where no terminal or line is provided).

The capacitor shown in FIG. 1 includes a lower electrode formed in the same step as the gate line, an upper electrode formed in the same step as the gate insulating film and the drain line.
In addition, a corner portion where electrostatic discharge is likely to occur, in particular, a left outer side of the gate terminal group electrically connected to the gate line, and an upper side of the drain terminal group electrically connected to the drain line,
And the second terminal, static electricity flows most easily through the capacitor via the two terminals (51) and (55). Thus the occurrence of a line defect due to a change in V _TH not flow static electricity can be prevented in the TFT of the pixel region.

This capacitor is provided for each terminal block.
That is, if there are two gate terminal groups, they may be provided between them, or if there are two drain terminal groups, they may be provided between them.

[0024]

As is clear from the above description, the first
Especially in active matrix type liquid crystal display devices,
Since the switching element has electrodes formed on the upper layer and the lower layer with the insulating layer interposed therebetween, a capacitor can be provided at the corner of the insulating substrate by utilizing these electrodes. Also, since the corner is most easily discharged, that is, in the area in contact with the space area where the terminal of the corner is not formed, the terminal electrically connected to the upper and lower electrodes of this capacitor is provided. The surge due to electrostatic discharge can be absorbed with a high probability.

Second, also in a liquid crystal display device using an inverted staggered transistor using a-Si or p-Si, a capacitor is provided at a corner similarly to the first effect described above, so that electrostatic discharge is prevented. It can be absorbed efficiently. The lower electrode can be formed in the same step as the gate line, the upper electrode can be formed in the same step as the drain line, and the dielectric layer can be formed in the same step as the gate insulating film.

Further, since this capacitor can be formed in a space area other than the display area, particularly, in a space area where no terminal is formed, it can be achieved without reducing the display area.

[Brief description of the drawings]

FIG. 1 is a plan view showing a corner of a liquid crystal display device of the present invention.

FIG. 2 is a sectional view taken along a second line in FIG.

FIG. 3 is a sectional view taken along a first line in FIG. 1;

FIG. 4 is a schematic plan view of a conventional liquid crystal display device.

FIG. 5 is a schematic plan view of the liquid crystal display device of the present invention.

FIG. 6 is a sectional view of a staggered p-Si TFT.

FIG. 7 is a cross-sectional view of the MIM.

FIG. 8 is a cross-sectional view of an inverted stagger type a-Si TFT.

[Explanation of symbols]

 (30) Transparent insulating substrate (31) Gate (32) Gate line (36) Display electrode (37) First non-single-crystal silicon film (39) Second non-single-crystal silicon film (40) Source electrode ( 41) Drain electrode (42) Drain line (51) First terminal (52) First line (55) Second terminal (56) Second line

Claims (2)

(57) [Claims] 1. A group of address terminals provided on one side of a transparent insulating substrate, a group of data terminals provided on the other side having a common corner with the one side, In a liquid crystal display device having a switching element electrically connected to a data terminal and a display electrode electrically connected to the switching element, an outermost address terminal and a data terminal in contact with the corner portion A liquid crystal display device provided with a capacitor for surge absorption, which uses an insulating film as a dielectric layer, which is one configuration of the switching element. 2. A gate line formed integrally with a gate formed on a transparent insulating substrate, a gate insulating film formed on the entire surface of the substrate including the gate line, and a TFT semiconductor having the gate as one component. A non-doped first non-single-crystal silicon film and a heavily doped N ⁺ -type second non-single-crystal silicon film serving as a region and a contact region, and a transparent electrode material formed near the TFT; A display electrode; and the second electrode corresponding to the source of the TFT.
A source electrode for electrically connecting the non-single-crystal silicon film to the display electrode, a drain electrode extending from the second non-single-crystal silicon film corresponding to the drain of the TFT, and a drain integrated therewith In a liquid crystal display device having at least a line, a first terminal formed in the same process as the gate terminal is provided outside a gate terminal group electrically connected to the gate line, Outside the electrically connected drain terminal group, a second terminal formed in the same step as the drain terminal is provided, and the first terminal is integrated with a line formed in the same step as the gate line to form a capacitor. The second terminal is integrated with a line formed in the same step as the drain line to form an upper electrode of a capacitor, and the second terminal is formed of a capacitor formed of the upper electrode and the lower electrode. A liquid crystal display device characterized by absorbing light.