US Patent 10096718 Transistor, electronic device, manufacturing method of transistor

Reducing the power consumption of a transistor and stably controlling its threshold value. Providing a transistor comprising a first conductive layer, a first insulating layer and a second insulating layer over the first conductive layer, a semiconductor layer over the first insulating layer, a third insulating layer over the first conductive layer and the semiconductor layer, a second conductive layer over the second insulating layer, and a gate electrode over the third insulating layer. The first conductive layer is in an electrically floating state. The first conductive layer has a region overlapping with the semiconductor layer with the first insulating layer provided therebetween, a region overlapping with the second conductive layer with the second insulating layer provided therebetween, and a region overlapping with the gate electrode with the third insulating layer provided therebetween.