THIN FILM TRANSISTOR AND MANUFACTURING METHOD THEREOF

A thin film transistor includes a semiconductor layer, a gate insulating layer, a gate, a source and a drain. The semiconductor layer has a first heavily doped region, a second heavily doped region, a third heavily doped region, an intrinsic region and a lightly doped region. The gate shields the intrinsic region and a first portion of the first heavily doped region. A second portion of the first heavily doped region is located outside an area of the gate. The source and the drain are electrically connected to the second heavily doped region and the third heavily doped region respectively. The source and the drain are arranged in a first direction. The first portion of the first heavily doped region and the gate have an overlapping region. A length of the overlapping region in the first direction is greater than a length of the intrinsic region in the first direction.