Thin film transistor and manufacturing method thereof

The invention provides a thin film transistor which comprises a polysilicon island, a gate insulated layer, a gate stack layer and a dielectric layer, wherein the polysilicon island comprises a source area and a drain area, and the gate stack layer covers the polysilicon island. The gate stack layer is arranged on the gate insulated layer, wherein the gate stack layer comprises a first conductive layer and a second conductive layer. The length of the first conductive layer is smaller than that of the second conductive layer. The dielectric layer covers the gate insulated layer and the gate stack layer, thereby a plurality of holes are formed between the second conductive layer and the gate insulated layer.