POLYCRYSTALLINE THIN FILM TRANSISTOR

摘要

PURPOSE: A polycrystalline thin film transistor is provided to enhance contrast ratio and brightness of an LCD by reducing an off-current of a thin film transistor thereby decreasing a cost of products, and to increase opening ratio of a pixel by reducing a size of a thin film transistor for pixel drive at an LCD. CONSTITUTION: A polysilicon thin film transistor comprises a glass substrate(80), an active layer and a gate(10). The active layer is formed on the substrate and is provided with a source(20) and a drain(30) in which an impurity is doped on both side of a channel(60) of the polysilicon. The gate and the active layer are insulated electrically and the gate is placed onto the channel. A mask layer(11) is provided on a top of the channel neighboring to the drain. An interval between the gate and the mask layer is in a range of 0.3-0.7 micrometer. The gate and the mask layer are formed as a same material and is placed in a co-plane each other. A width of the mask layer is in a range of 0.3-0.7 micrometer.