Semiconductor device and method of manufacturing the semiconductor device

Abstract

An object is to provide a semiconductor device provided with a thin film transistor having excellent electric characteristics using an oxide semiconductor layer. An In—Sn—O-based oxide semiconductor layer including SiO X is used for a channel formation region. In order to reduce contact resistance between the In—Sn—O-based oxide semiconductor layer including SiO X and a wiring layer formed from a metal material having low electric resistance, a source region or drain region is formed between a source electrode layer or drain electrode layer and the In—Sn—O-based oxide semiconductor layer including SiO X . The source region or drain region and a pixel region are formed using an In—Sn—O-based oxide semiconductor layer which does not include SiO X .

1 . (canceled) 
     
     
         2 . A semiconductor device comprising:
 a gate electrode layer;   a gate insulating layer;   a first oxide semiconductor layer including In;   a second oxide semiconductor layer including In and N in contact with the first oxide semiconductor layer; and   a pixel electrode,   wherein the pixel electrode is in the second oxide semiconductor layer.   
     
     
         3 . A semiconductor device according to  claim 2 , wherein conductivity of the first oxide semiconductor layer is less than or equal to 1.6×10 −3  S/cm. 
     
     
         4 . The semiconductor device according to  claim 2 , wherein the first oxide semiconductor layer is formed by a sputtering method using a target including In and O. 
     
     
         5 . A semiconductor device according to  claim 2 , further comprising a liquid crystal layer interposed between the pixel electrode and a counter electrode. 
     
     
         6 . A semiconductor device according to  claim 2 , further comprising a light-emitting layer over an anode in the pixel electrode, and a cathode over the light-emitting layer. 
     
     
         7 . A semiconductor device according to  claim 2 , further comprising a light-emitting layer provided over a cathode provided in the pixel electrode, and an anode over the light-emitting layer. 
     
     
         8 . A semiconductor device according to  claim 2 , wherein nitrogen is added to the second oxide semiconductor layer. 
     
     
         9 . A semiconductor device according to  claim 2 , wherein a channel region is in the first oxide semiconductor layer. 
     
     
         10 . The semiconductor device according to  claim 2 , wherein the first oxide semiconductor layer further includes Si. 
     
     
         11 . A semiconductor device comprising:
 a gate electrode layer over a substrate having an insulating surface;   a gate insulating layer over the gate electrode layer;   a first oxide semiconductor layer including In and Si over the gate insulating layer;   a second oxide semiconductor layer including In in contact with the first oxide semiconductor layer; and   a pixel electrode,   wherein the pixel electrode is in the second oxide semiconductor layer.   
     
     
         12 . The semiconductor device according to  claim 11 , wherein a conductivity of the first oxide semiconductor layer is less than or equal to 1.6×10 −3  S/cm. 
     
     
         13 . The semiconductor device according to  claim 11 , wherein the first oxide semiconductor layer is formed by a sputtering method using a target including In, Si, and O where a concentration of SiO 2  is 5 wt % or higher and 50 wt % or lower. 
     
     
         14 . The semiconductor device according to  claim 11 , wherein nitrogen is added to the second oxide semiconductor layer. 
     
     
         15 . The semiconductor device according to  claim 11 , wherein a channel region is in the first oxide semiconductor layer. 
     
     
         16 . The semiconductor device according to  claim 11 , wherein the first oxide semiconductor layer further includes Sn. 
     
     
         17 . The semiconductor device according to  claim 11 , wherein the second oxide semiconductor layer further includes Sn.