Patent ID: 8338226
Filing Date: 2012-12-25
Classification: C04B,H01L

Abstract:
1. A manufacturing method of a semiconductor device, comprising the steps of: forming a gate electrode layer over a substrate; forming a gate insulating layer over the gate electrode layer; forming a conductive film over the gate insulating layer; forming a first oxide semiconductor film over the conductive film; etching the conductive film and the first oxide semiconductor film to form a source electrode layer, a drain electrode layer, a second oxide semiconductor film, and a third oxide semiconductor film, wherein the second oxide semiconductor film is provided over the source electrode layer and the third oxide semiconductor film is provided over the drain electrode layer; performing reverse sputtering treatment on the second oxide semiconductor film and the third oxide semiconductor film; performing a first heat treatment in a nitrogen atmosphere after forming the second oxide semiconductor film and the third oxide semiconductor film; forming a fourth oxide semiconductor film over the gate insulating layer, the second oxide semiconductor film, and the third oxide semiconductor film; and etching the second to fourth oxide semiconductor films to form a first buffer layer, a second buffer layer, and an oxide semiconductor layer, wherein the first buffer layer is formed from the second oxide semiconductor film and the second buffer layer is formed from the third oxide semiconductor film.