THIN FILM TRANSISTOR, AND ACTIVE MATRIX SUBSTRATE AND DISPLAY DEVICE PROVIDED WITH SUCH THIN FILM TRANSISTOR

摘要

Current drive performance of a thin film transistor is improved without yield deterioration due to a leak failure between a source/drain electrodes and a gate electrode and that due to deterioration of off-characteristics. The thin film transistor is provided with a gate electrode; an insulating film covering the gate electrode; a semiconductor layer arranged on the insulating film; and the source electrode and the drain electrode arranged on the insulating film and the semiconductor layer. The insulating film is a multilayer insulating film including a first insulating layer and a second insulating layer positioned on the upper layer of the first insulating layer. The multilayer insulating film is provided with a low laminated region whereupon no first insulating layer is formed, and a high insulating region whereupon the first insulating layer and the second insulating layer are stacked. The first insulating layer is formed to cover at least the edge of the gate electrode. The semiconductor layer is formed over both the low laminated region and the high laminated region of the multilayer insulating film. The semiconductor layer and the low laminated region are arranged to permit the route of a current flowing between the source electrode and the drain electrode to surely go through a portion at the low laminated region on the semiconductor layer.