Semiconductor device and manufacturing method thereof

Abstract

To provide a semiconductor device including an oxide semiconductor, which has stable electric characteristics and has high reliability. To provide a method for manufacturing the semiconductor device. The semiconductor device includes a gate electrode, a gate insulating film formed over the gate electrode, an oxide semiconductor film formed over the gate insulating film, a source electrode and a drain electrode formed over the oxide semiconductor film, and a protective film. The protective film includes a metal oxide film, and the metal oxide film has a film density of higher than or equal to 3.2 g/cm 3 .

1 . (canceled) 
     
     
         2 . A semiconductor device comprising:
 an oxide semiconductor film over an insulating surface;   a source electrode and a drain electrode over the oxide semiconductor film;   an oxide insulating film over and in contact with the oxide semiconductor film, the source electrode, and the drain electrode; and   a first metal oxide film over the oxide insulating film,   wherein the first metal oxide film has a film density of higher than or equal to 3.2 g/cm 3 ,   wherein the source electrode overlaps with a first end of the oxide semiconductor film, and   wherein the drain electrode overlaps with a second end of the oxide semiconductor film.   
     
     
         3 . The semiconductor device according to  claim 2 , further comprising a second metal oxide film in contact with the oxide semiconductor film. 
     
     
         4 . The semiconductor device according to  claim 2 ,
 wherein the first metal oxide film comprises aluminum oxide.   
     
     
         5 . The semiconductor device according to  claim 2 ,
 wherein the first metal oxide film comprises Ga—Zn-based oxide.   
     
     
         6 . The semiconductor device according to  claims 2 ,
 wherein the oxide semiconductor film comprises at least one oxide of indium, zinc, gallium, zirconium, tin, gadolinium, titanium, and cerium.   
     
     
         7 . The semiconductor device according to  claim 2 ,
 wherein the oxide insulating film comprises a region in which the oxygen content is higher than the stoichiometric proportion.   
     
     
         8 . A semiconductor device comprising:
 a gate electrode;   a gate insulating film over the gate electrode;   an oxide semiconductor film over the gate insulating film;   a source electrode and a drain electrode over the oxide semiconductor film; and   a protective film over the oxide semiconductor film, the source electrode, and the drain electrode,   wherein the protective film is a stack in which a first metal oxide film is provided over an oxide insulating film,   wherein the oxide insulating film is in contact with the oxide semiconductor film,   wherein the first metal oxide film has a film density of higher than or equal to 3.2 g/cm 3 ,   wherein the source electrode overlaps with a first end of the oxide semiconductor film, and   wherein the drain electrode overlaps with a second end of the oxide semiconductor film.   
     
     
         9 . The semiconductor device according to  claim 8 ,
 wherein the first metal oxide film comprises aluminum oxide.   
     
     
         10 . The semiconductor device according to  claim 8 ,
 wherein the first metal oxide film comprises Ga—Zn-based oxide.   
     
     
         11 . The semiconductor device according to  claim 8 , further comprising a conductive film in contact with the first metal oxide film of the protective film. 
     
     
         12 . The semiconductor device according to  claim 11 ,
 wherein the conductive film includes at least one of zinc oxide, indium tin oxide, titanium oxide, aluminum, and titanium.   
     
     
         13 . The semiconductor device according to  claim 8 ,
 wherein the oxide semiconductor film includes at least one oxide of indium, zinc, gallium, zirconium, tin, gadolinium, titanium, and cerium.   
     
     
         14 . The semiconductor device according to  claim 8 , further comprising a second metal oxide film over and in contact with the gate insulating film. 
     
     
         15 . The semiconductor device according to  claim 8 , further comprising a base insulating film under and in contact with the gate electrode,
 wherein the base insulating film includes a third metal oxide film in contact with the gate electrode, and   wherein a film density of the third metal oxide film is higher than or equal to 3.2 g/cm 3 .   
     
     
         16 . The semiconductor device according to  claim 8 ,
 wherein the oxide insulating film comprises a region in which the oxygen content is higher than the stoichiometric proportion.