Patent ID: 6278504
Filing Date: 2001-08-21
Classification: G02F

Abstract:
A thin film transistor for liquid crystal display device comprising:a gate electrode formed on a transparent substrate;an insulation layer formed to cover an upper surface of the transparent substrate and the gate electrode;a semiconductor layer formed on the insulation layer disposed above the gate electrode and having a longitudinal width, a lateral width and a pair of edges, the gate electrode disposed to shade the semiconductor layer from light incident from a lower surface side of the transparent substrate;an etching stopper layer formed on the semiconductor layer; anda source electrode, a drain electrode and corresponding ohmic contact layers for the source electrode and the drain electrode, the source and drain electrodes and corresponding ohmic contact layers disposed over opposing sides of the semiconductor layer, the etching stopper layer, and the insulation layer, the source and drain electrodes connected with the semiconductor layer only through the corresponding ohmic contact layer;wherein an area of a projection of the semiconductor layer coplanar with a projection of an area of the gate electrode is contained within the projection of the area of the gate electrode,the longitudinal width of the semiconductor layer is smaller than longitudinal widths of the etching stopper layer and of the source and drain electrodes over the entire lateral width of the semiconductor layer,the etching stopper layer covers the entire semiconductor layer between the source and drain electrode, andthe etching stopper layer and longitudinal widths of the source electrode and the drain electrode are sized to stop optical current from being generated in the semiconductor layer originating from light incident from an upper surface side of the transparent substrate.