Patent ID: 9640639
Date: 2017-05-02
CPC Classifications: H01L

Claim:
1. A method for manufacturing a semiconductor device, comprising the steps of: forming a conductive layer; forming an oxide insulating film over the conductive layer, the oxide insulating film having a projection over the conductive layer; performing oxygen doping treatment on the oxide insulating film to selectively form an oxygen excess region in the oxide insulating film; performing polishing treatment on the oxide insulating film including the oxygen excess region to planarize the projection after the oxygen doping treatment; forming an oxide semiconductor layer including a channel formation region over the planarized oxide insulating film; forming a source electrode layer and a drain electrode layer electrically connected to the oxide semiconductor layer; forming a gate insulating film over the oxide semiconductor layer; and forming a gate electrode layer overlapping with the channel formation region with the gate insulating film interposed therebetween.