Patent ID: 8809154
Filing Date: 2014-08-19
Classification: G02F,H01L

Abstract:
1. A method for manufacturing a semiconductor device, the method comprising the steps of: forming a gate electrode layer over a substrate; forming a first gate insulating film over the gate electrode layer; forming a second gate insulating film over the first gate insulating film; performing a first heat treatment at a temperature higher than or equal to 450° C. after the formation of the second gate insulating film; forming an oxide semiconductor film over the second gate insulating film after the first heat treatment; and performing a second heat treatment after the formation of the oxide semiconductor film, wherein the first gate insulating film is formed by a plasma CVD method using a first RF power, a silane gas, a nitrogen gas, and an ammonia gas, wherein the second gate insulating film is formed by a plasma CVD method using a second RF power, a silane gas and a nitrogen dioxide gas, and wherein the first RF power is higher than the second RF power.