With such characteristics as small volume, low power consumption and less radiation, Thin Film Transistor Liquid Crystal Displays (TFT-LCDs) have dominated the current market of flat panel displays. With the development of technology, customers have placed more requirements on the display effect of the mobile products. The ordinary Twisted Nematic (TN) type liquid crystal displays have become inadequate to meet the requirements of the market with regard to the display effect.
At present, many manufacturers gradually apply the various wide viewing-angle technologies which have better display effects for the mobile products, e.g., In-Plane-Switching (IPS), Vertical Alignment (VA), Advanced Super Dimension Switch (AD-SDS, or simplified as ADS) technologies and the like. With the ADS mode, a multi-dimensional electric field is formed with an electric field produced at edges of slit electrodes on a same plane and an electric field produced between a layer of the slit electrodes and a layer of a plate-like electrode so as to allow liquid crystal molecules at all orientations within a liquid crystal cell, which are located between the slit electrodes and directly above the slit electrodes, to be rotated, thereby enhancing the work efficiency of liquid crystals and increasing the light transmittance. Thus, the ADS technology can improve the picture quality of the TFT-LCDs, and has advantages such as high transmittance, wide viewing angle, high aperture ratio, low chromatic aberration, low response time, no push Mura, and etc.
FIG. 1 shows a TFT array substrate structure with the current ADS mode, in which a cross-sectional schematic view of a pixel region is shown. In the array substrate, the lowest layer is a glass substrate 1, and a gate electrode 2, an insulating layer 3, an active layer 4 are sequentially formed on the glass substrate 1. A drain electrode 5 and a source electrode 6 are formed on the active layer 4. In a direction of the light transmission (i.e., the vertical direction in the figure), regions related to the drain electrode 5 and the source electrode 6 constitute a thin film transistor (TFT) region in a pixel region. A pixel electrode 7 (which may be deemed as a plate-like electrode) is formed on the insulating layer 3 and contacts the drain electrode 5. The source electrode 6 and a data line (not shown) are formed integrally. A passivation layer 9 is formed on the drain electrode 5, the source electrode 6 and the pixel electrode 7, and a common electrode 8 (which may be deemed as a slit electrode) is formed on the passivation layer 9. In the direction of the light transmission, regions related to the pixel electrode 7 and the common electrode 8 constitute a pixel electrode pattern region (or called as “display region”).
A process for manufacturing the structure of the aforesaid array substrate is generally shown in FIG. 2. When the structure is applied to small-sized mobile products, the aperture ratio will be increased to a certain extent because there is no via hole in a pixel. But since an additional color filter substrate is required thereon, the bonding of the manufacturing process will lead to lowered aperture ratio due to the bonding condition of the edges.
In addition, it can be seen from FIG. 1 that a step exists between the TFT structure and an upper surface of the data line (the source electrode 6). Apparently, the step hamper the application of horizontal driving in the ADS mode, so the liquid crystal can not be normally driven here, thus causing light leakage and lowered contrast ratio (CR).