JPH09120082A - Active matrix type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient contact without lowering opening rate by forming the contact parts between source electrodes and display pixel electrodes by utilizing the outer peripheral parts of the display pixel electrodes. SOLUTION: Scanning lines 50 and signal lines 51 continuous across the respective pixels are arrayed in a matrix form and thin-film transistors(TFTs) 52 are formed in the crossing point parts thereof. These TFTs 52 are constituted of gate electrodes integral with the scanning lines 50 and source electrodes 7 and drain electrodes 8 formed to face each other via gate insulating films and semiconductor layers thereon. In this case, the junctures of the source electrodes 7 and the display pixel electrodes 9 are so formed as to enclose the display pixel electrodes 9 along the three sides of the display pixel electrodes 3 and have the parts along the longitudinal direction of the channels of the TFTs 52 and the parts 10 extending to both sides of the display pixel electrodes 9 along the transverse direction of the channels. Further, the junctures 10 are so disposed as to be superposed on storage capacitance electrodes 3.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION

[0002]

2. Description of the Related Art Thin film transistors (Thin Film) are described below.
A conventional technique will be described by taking as an example an active matrix type liquid crystal display device in which a display pixel electrode array is configured by using a transistor (hereinafter abbreviated as TFT) as a switch element.

The basic structure of an active matrix type liquid crystal display device is that a liquid crystal substance is sealed in a gap between an array electrode on which a display pixel electrode array is formed and a counter substrate on which a counter electrode is formed. FIG. 5 shows a schematic plan view of one pixel of the array substrate. The TFT 52 and the TFT 5 are provided on the array substrate.
The transparent display pixel electrodes 9 connected to the two source electrodes 7 are formed in a matrix, and further, the scanning lines 50 commonly connected to the gates of the respective TFTs arranged in the row direction, and the scanning lines 50 arranged in the column direction. A signal line 51 commonly connected to the drain electrode 8 of each TFT, a storage capacitor line 3 and the like which are arranged opposite to the display pixel electrode 9 via an insulating layer and constitute a storage capacitor are formed as necessary. ing.

By the way, in the active matrix type liquid crystal display device, lower power consumption and improvement of surface brightness are required, and it is an important technical subject to raise the aperture ratio which represents the area ratio of transmitting light. ing. In order to increase the aperture ratio, the area occupied by the transparent pixel electrode of one pixel is made as large as possible, and the area occupied by the scanning line, the signal line, the storage capacitor line or the like, which is a light shielding film, or the TFT is made as small as possible. It is necessary. Specifically, making the wiring width as narrow as possible and the TFT size as small as possible leads to an improvement in the aperture ratio.

[0005]

However, if the wiring width of the scanning line, the signal line, etc. is reduced, the probability of disconnection increases and the yield decreases. Further, if the storage capacitance line is made thin, a desired capacitance value cannot be obtained, and there is a possibility that fluctuations in pixel electrode potential and crosstalk will increase.
Further, when the size of the TFT is reduced, the ability to drive the pixel is insufficient, and the contrast ratio may be lowered. In view of such technical background, it is an object of the present invention to improve the aperture ratio without lowering the manufacturing yield or deteriorating the image quality.

[0006]

According to the present invention, the connecting portion between the source electrode of the TFT and the display pixel electrode is formed along the contour line of two adjacent sides of the display pixel electrode. Thereby, the area required for contacting the source electrode and the display pixel electrode can be secured. The outer peripheral portion of the display pixel electrode is shielded in order to eliminate light leakage between adjacent pixels, and a contact region can be formed by utilizing this region, so that the aperture ratio can be improved. It will be possible.

[0007]

DETAILED DESCRIPTION OF THE INVENTION An active matrix type liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic plan view of one pixel of an array substrate manufactured according to this embodiment, and FIG. 2 is a line A of FIG.
A sectional view along A is shown. That is, the scanning lines 50 and the signal lines 51 are continuously arranged in a matrix over each pixel, and the TFTs 52 are formed at the intersections thereof. T
The FT 52 is composed of a gate electrode 2 integrated with the scanning line 50, and a source electrode 7 and a drain electrode 8 made of a light-shielding metal formed on the gate electrode 2 so as to face each other with a gate insulating film 4 and a semiconductor layer 5 therebetween. There is. An ohmic layer 6 made of an impurity-doped semiconductor layer is formed between the source electrode 7 and the drain electrode 8 and the semiconductor layer 5. The source electrode 7 is connected to the display pixel electrode 9, while the drain electrode 8 is formed integrally with the signal line 51. Further, a storage capacitor electrode 3 is formed immediately below the display pixel electrode 9 so as to face it with the gate insulating film 4 interposed therebetween.

The connecting portion between the source electrode 7 and the display pixel electrode 9 is formed so as to surround the display pixel electrode 9 along the three sides of the display pixel electrode as shown in the figure, and the TFT 5
2 has a portion along the channel length direction and a portion 10 extending on both sides of the display pixel electrode 9 along the channel width direction. The connecting portion 10 is provided so as to overlap the storage capacitor electrode 3.

Next, a manufacturing process of this array substrate will be described. A Ta film is deposited on a light-transmissive insulating substrate 1 such as glass by using a sputtering method, and then is patterned into a desired shape by using a PEP method, and scanning lines 50 continuous in the row direction and an external circuit (not shown) are formed. A storage capacitor electrode 3 was formed as a connection terminal for the connection. Then, a silicon oxide film, an amorphous silicon film, and an n + amorphous silicon film are sequentially laminated by a CVD method, these semiconductor layers are patterned into a desired shape, and further, an ITO film is formed and then patterned into a desired shape to display The pixel electrode 9 was formed. Then, an Al film was deposited by the sputtering method, and the source electrode 7, the drain electrode 8 and the signal line 51 integrated with the source electrode 7 were formed by the PEP method.

The array substrate thus manufactured is
The active substrate type liquid crystal display device was manufactured by combining and sealing with the counter substrate 21 shown in FIG. 2 and injecting a liquid crystal substance into the gap. As shown in the figure, the counter electrode 22 made of a transparent electrode such as ITO is formed on the entire inner surface of the counter substrate 21, and although not shown, the liquid crystal of the array substrate 20 and the counter substrate 21 is formed. An alignment film is formed in a portion in contact with the film as needed. The opposite substrate 2
A light shielding layer is formed in a region facing the gap between the two display pixel electrodes, and R, G, and
The B color filter layer may be formed.

In this embodiment, the contact portion between the source electrode and the display pixel electrode is formed by utilizing the region shielded by the storage capacitor electrode 3. Therefore, it is possible to increase the effective pixel area and improve the aperture ratio.

Further, this embodiment can be modified. For example, as shown in the drawing, contact portions are formed on both sides of the pixel electrode 9 parallel to the channel width direction of the TFT,
In addition, if the source electrode is slightly protruded on both sides of the display pixel electrode 9 in this contact portion, even if a displacement occurs along the channel length direction of the TFT in the process of forming the pixel electrode 9 and the source electrode 7, respectively. The area of the contact portion can be made constant as the sum of the areas of the contact portions on both sides. At this time, if the shape of the outer periphery of the source electrode fits into the outer periphery of the storage capacitor electrode 3, the aperture ratio does not decrease.

Further, as shown in FIG. 4, a contact portion may be superposed on the light shielding layer 30 (shown by a dotted line in the drawing) on the counter substrate side. With this structure, it is possible to improve the aperture ratio as in the above embodiment.

[0014]

According to the present invention, since the contact portion between the source electrode and the display pixel electrode is formed by utilizing the outer peripheral portion of the display pixel electrode, sufficient contact can be obtained without reducing the aperture ratio. Is possible.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of one pixel of an active matrix liquid crystal display device according to an embodiment of the present invention.

2 shows a cross-sectional view along the line AA 'in FIG.

FIG. 3 shows a cross-sectional view taken along the line BB ′ of FIG.

FIG. 4 is a schematic plan view of one pixel of an active matrix type liquid crystal display device according to another embodiment of the present invention.

FIG. 5 is a schematic plan view of one pixel of a conventional active matrix type liquid crystal display device.

[Explanation of symbols]

 3 ... Storage capacitor electrode 7 ... Source electrode 9 ... Display pixel electrode 30 ... Light shielding layer 52 ... TFT

Claims (5)

[Claims] 1. A first substrate having a thin film transistor having a drain electrode, a source electrode and a gate electrode and a transparent pixel electrode connected to the source electrode, and a second substrate having a counter electrode formed thereon. In an active matrix type liquid crystal display device having a liquid crystal layer sandwiched therebetween, the source electrode is a connection portion with the transparent pixel electrode and extends along the contour line of two or more adjacent sides of the transparent pixel electrode. An active matrix type liquid crystal display device characterized by having a shape. 2. The active matrix type liquid crystal display device according to claim 1, wherein the connection portions are provided at positions facing each other with the transparent pixel electrode interposed therebetween. 3. The connection portion has a portion extending along a direction parallel to the channel length direction of the thin film transistor and a portion extending along a direction parallel to the channel width direction. The active matrix type liquid crystal display device according to claim 1. 4. The active matrix type liquid crystal display device according to claim 1, wherein the source electrode is made of a light shielding metal. 5. The active matrix type liquid crystal display according to claim 3, wherein at least one of the extending portions is overlapped with a light shielding layer provided on the first substrate or the second substrate. apparatus.