JPH04324820A - Active matrix type liquid crystal display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix liquid crystal display device.

0002

BACKGROUND OF THE INVENTION In conventional active matrix liquid crystal display devices, unevenness between pixel electrodes and other switching elements and wiring in the display area is not taken into consideration.
The insulating film is not formed only under the pixel electrode.

0003

[Problems to be Solved by the Invention] In the above-mentioned prior art, since the pixel electrode has a concave structure than the adjacent switching elements and wiring, the rubbing process for aligning the liquid crystal by mechanically rubbing the substrate is difficult. There is a problem in that other elements and wiring become obstacles to rubbing on the pixel electrode, leading to a decrease in the alignment force of the liquid crystal on the pixel electrode, and display abnormalities occur.

[0004] Furthermore, the occurrence of the display abnormality, which is the problem mentioned above, is caused by
The higher the pixel density, the more noticeable this becomes. This is because, as long as the same design rules are used, even if the pixel density is increased and the pixel pitch is made finer, the area of the elements and wiring remains the same, and the area of the pixel electrode decreases. This is because the area occupied will be relatively increased.

[0005]

[Means for solving the problem] In order to avoid the pixel electrode from being more concave than other elements and wiring, an insulating film is laid under the pixel electrode so that the pixel electrode is more concave than other elements and wiring. Alternatively, structures with the same height can be obtained.

Furthermore, by forming the insulating film in the same process as an interlayer insulating film for elements, wiring, etc., it is possible to form the insulating film under the pixel electrode without adding extra manufacturing steps.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this description, for the sake of brevity, only the relationship between wiring and pixel electrodes will be focused and mentioned. FIG. 1 is a simplified cross-sectional view of the embodiment. In the drawings, 1 is a wiring, 2 is a pixel electrode, and 3 is an insulating substrate and a lower layer.

In FIG. 1, after the wiring 1 and layers other than the pixel electrode 2 and the pattern 3 are formed on the insulating substrate, the insulating film 4 is formed under the pixel electrode 2, and then the pixel electrode 2 and the wiring 1 are formed. Form. Therefore, by changing the thickness of the insulating film 4, it is possible to control surface irregularities within the display area. Furthermore, if the liquid crystal display device is of a transmission type, the insulating film 4 must also be made of a transparent material. For example, it is effective to use photosensitive transparent polyimide, which has excellent patterning properties. In addition, in the case of driver-built-in liquid crystal display devices where the drive circuit is formed on the same substrate,
As the pixel pitch becomes smaller, the need for multilayer wiring increases. The interlayer insulating film and pixel electrode 2 of such multilayer wiring
If the insulating film 4 is formed from the same material and in the same process as the insulating film 4 laid under the insulating film 4, no additional manufacturing steps will be required, the process will be simplified, and mass productivity will be improved.

FIG. 2 is a simplified cross-sectional view of a conventional device. In FIG. 2, since the wiring 1 and the pixel electrode 2 have different thicknesses, surface irregularities exist within the display area. This is because the resistance of the wiring 1 must be lowered in order to prevent horizontal and vertical unevenness in the display, and the wiring 1 tends to become thicker. However, the pixel electrode 2 needs to be made thin due to restrictions in the manufacturing process. For example, when indium tin oxide or the like is used for the pixel electrode, it is difficult to increase the thickness because problems such as a decrease in transmittance and increased side etching during the photolithography process occur. If surface irregularities exist in the display area in this way, the wiring 1, which is a convex part, becomes an obstacle to rubbing on the pixel electrode, which is a concave part, in the rubbing process that aligns the liquid crystal by mechanically rubbing the substrate. , the alignment force of the liquid crystal decreases and display abnormalities occur. Therefore, pixel electrode 2
By laying the insulating film 4 under the pixel electrode 4 to flatten the surface, it is possible to eliminate the problem of rubbing on the pixel electrode 2 that contributes to display. Therefore, good orientation can be obtained.

0010

[Effects of the Invention] In an active matrix type liquid crystal display device, by laying an insulating film under the pixel electrode and correcting and flattening the unevenness in the display area, it is possible to eliminate problems caused by rubbing on the pixel electrode. The present invention provides an active matrix liquid crystal display device that can achieve good alignment.

[Brief explanation of drawings]

FIG. 1 is a simplified main cross-sectional view of an embodiment of the invention.

FIG. 2 is a simplified main cross-sectional view of a conventional example.

[Explanation of symbols]

1 Wiring 2 Pixel electrode 3 Layers and patterns other than 1 and 2 and insulating substrate 4
Insulating film

Claims (2)

[Claims] 1. An active device comprising, on an insulating substrate, a plurality of scanning lines and signal lines, and switching elements and pixel electrodes disposed at intersections of the scanning lines and the signal lines, and which displays by driving a liquid crystal. An active matrix liquid crystal display device characterized by a structure in which an insulating film is provided under the pixel electrode to flatten the inner surface of the display area. 2. The active matrix liquid crystal display device according to claim 1, wherein the insulating film laid under the pixel electrode is formed in the same process as an interlayer insulating film for elements, wiring, etc.