Thin film transistor having four different gate electrodes

摘要

Provided is a transistor including an oxide semiconductor in a channel formation region in which the threshold voltage is controlled, which is a so-called normally-off switching element. The switching element includes a first insulating film, an oxide semiconductor layer over the first insulating film and includes a channel formation region, a second insulating film covering the oxide semiconductor layer, a source electrode layer and a drain electrode layer electrically connected to the oxide semiconductor layer. The semiconductor device further includes a first gate electrode layer overlapping the channel formation region with the first insulating film therebetween, a second gate electrode layer overlapping the channel formation region with the second insulating film therebetween, and a third gate electrode layer overlapping a side surface of the oxide semiconductor layer in a channel width direction with the second insulating film therebetween.

主权项

1. A semiconductor device comprising:
a first gate electrode layer; a first insulating film over the first gate electrode layer; an oxide semiconductor layer comprising a channel formation region and overlapping the first gate electrode layer with the first insulating film therebetween; a source electrode layer and a drain electrode layer over and electrically connected to the oxide semiconductor layer; a second insulating film over the oxide semiconductor layer, the source electrode layer, and the drain electrode layer; a second gate electrode layer overlapping the channel formation region with the second insulating film therebetween; a third gate electrode layer over the second insulating film and overlapping a first end portion of the oxide semiconductor layer; and a fourth gate electrode layer over the second insulating film and overlapping a second end portion of the oxide semiconductor layer that is opposite the first end portion; wherein the third gate electrode layer and the fourth gate electrode layer each extend in a direction that intersects with a channel length direction of the channel formation region.