SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To control a threshold voltage of a transistor without channel doping.SOLUTION: A semiconductor device comprises: a gate electrode; a first insulation film on the gate electrode; a second insulation film on the first insulation film; a semiconductor layer on the second insulation film; and a third insulation film on the semiconductor layer. The first insulation film includes nitrogen and silicon. The second insulation film includes nitrogen, oxygen and silicon. The third insulation film includes nitrogen, oxygen and silicon. The semiconductor layer has a channel formation region in a region overlapping a gate. Channel doping is not performed on the channel formation region.