SEMICONDUCTOR DEVICE AND MANUFACTURING METHOD THEREOF

摘要

An object is to reduce to reduce variation in threshold voltage to stabilize electric characteristics of thin film transistors each using an oxide semiconductor layer. An object is to reduce an off current. The thin film transistor using an oxide semiconductor layer is formed by stacking an oxide semiconductor layer containing insulating oxide over the oxide semiconductor layer so that the oxide semiconductor layer and source and drain electrode layers are in contact with each other with the oxide semiconductor layer containing insulating oxide interposed therebetween; whereby, variation in threshold voltage of the thin film transistors can be reduced and thus the electric characteristics can be stabilized. Further, an off current can be reduced.

主权项

1. A method for manufacturing 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 first oxide semiconductor film over the gate insulating layer by a sputtering method; forming a second oxide semiconductor film containing silicon oxide, over the first oxide semiconductor film, by a sputtering method using a target containing SiO2; etching the first oxide semiconductor film and the second oxide semiconductor film to form a first oxide semiconductor layer and a second oxide semiconductor layer containing silicon oxide; forming a conductive layer over the second oxide semiconductor layer; and etching the conductive layer to form a source electrode layer and a drain electrode layer, wherein the target containing SiO2 contains SiO2 at from 0.1% by weight to 30% by weight.