A thin film transistor-liquid crystal display (TFT-LCD) and a method of manufacturing the same prevent a short by forming a pixel electrode and a data line on different layers, and enhance the resultant image produced by the TFT-LCD by forming a passivation layer at a lower pixel electrode. To form this TFT-LCD, a gate electrode and an adjacent gate electrode are formed on a substrate. A gate insulating layer is then deposited on both the gate electrode and the adjacent gate electrode and an amorphous silicon layer, an N.sup.+ amorphous silicon layer, and a source/drain metal are sequentially formed on the gate insulating layer, and partially etched. A passivation layer surrounds the source/drain metal and the amorphous silicon layer is etched using the passivation layer as a mask. A pixel electrode is then formed on the upper gate insulating layer in which the amorphous silicon layer is not deposited.
A liquid crystal display device and a method of fabricating the same are disclosed. The device, as disclosed, reduces the number of masks required for fabrication. Thus, cost is reduced and yield is increased. The device includes a plurality of gate lines, a plurality of data lines crossing the gate lines such that active regions are defined near the crossover points, thin film transistors are formed near the active regions, and a plurality of pixel electrodes are formed within regions defined by the adjacent gate and data lines. Also, pixel electrodes overlap gate lines and the two electrodes function as a storage capacitor. A fabrication method includes forming a gate line; forming a data line region, protection layers, and an active area where drain and source electrodes are spaced apart at a predetermined distance; forming a data line, a gate line protection layer, and a gate insulating layer; and forming pixel electrodes by depositing a transparent conductive material, such that each pixel electrode also overlaps a portion of a gate line.
In a semiconductor device such as a thin film transistor, a semiconductor region is formed and an insulating film is formed on the semiconductor region to have a contact hole extending to the semiconductor region. An electrically conductive metal layer is formed of aluminium to fill the contact hole. An electrically conductive protection layer is formed on the metal layer to prevent oxidation of the metal layer during manufacturing of the semiconductor device. Material of the protection layer is more difficult to be oxidized than aluminium. A transparent electrode is formed on the protection layer such that the electrode is electrically connected to the semiconductor region. The protection layer may be formed of titanium or a laminate layer of a titanium layer and a titanium nitride layer.
In a method for manufacturing an LCD device where a gate insulating layer is formed on an insulating substrate and a signal line pattern layer and a pixel electrode pattern layer are formed on a signal line forming area and a pixel electrode forming area, respectively, of the gate insulating layer, a part of the gate insulating layer between the signal line forming area and the pixel electrode forming area is etched.
A gate insulating layer, an amorphous silicon layer, an n.sup.+ amorphous silicon layer and a metal layer are deposited in sequence after a gate line, a gate electrode and a gate pad are formed on a substrate, using a first mask. The metal layer is etched to form a data line, a source electrode, a drain electrode and a data pad through a photolithography process, using a second mask, and the n.sup.+ amorphous silicon layer is etched, using the patterned data line, the source electrode, the drain electrode and the data pad as the mask. A light shielding film and a passivation film, or a passivation film also having a function of the light shielding film are deposited, and is etched through the photolithography process, using a third mask which leaves a portion covering the gate line, the gate electrode, the gate pad and the data line, the source electrode, and the drain electrode. The amorphous silicon layer and the gate insulating layer are etched, using the patterned light shielding film and passivation film, or the patterned passivation film also having the function of the light shielding film as the mask. Here, the gate pad, the data pad and a part of the drain electrode are exposed. A pixel electrode connected to the drain electrode, is formed and indium tin oxide (ITO) pads covering the exposed gate pad and the exposed data pad, is formed by depositing an ITO film and etching thorough the photolithography, using a fourth mask. As a result, a thin film transistor array panel used for a liquid crystal display is fabricated by only four masks.
In the formation and structure of a thin film transistor (TFT), an insulator is formed to cover the surface of the transistor gate electrode, which electrode is separated from an underlying semiconductor layer, having defined source, drain and channel regions, by a gate insulating layer. The overlying gate insulator is formed by anodic oxidation of the gate electrode metal. The formation of the gate insulator thickness and its lateral offset, .DELTA.L, which is defined as the lateral spatial separation between the gate electrode and the source or drain region, can be accurately controlled by the gate electrode anodic oxidation process to provide a reliably and reproducible low OFF current, I.sub.OFF, resulting in a TFT that provides for a large I.sub.ON /I.sub.OFF ratio useful in large area applications wherein electrical charge is required, such as, liquid crystal displays and memory integrated circuits. Preferably, the metal gate electrode is subjected to anodic oxidation at a voltage within the range of between approximately 150 V to 250 V achieving a lateral offset, .DELTA.L, in the range of approximately 100 nm to 200 nm.
