Method for manufacturing semiconductor device

Abstract

It is an object to drive a semiconductor device at high speed or to improve the reliability of the semiconductor device. In a method for manufacturing the semiconductor device, in which a gate electrode is formed over a substrate with an insulating property, a gate insulating film is formed over the gate electrode, and an oxide semiconductor film is formed over the gate insulating film, the gate insulating film is formed by deposition treatment using high-density plasma. Accordingly, dangling bonds in the gate insulating film are reduced and the quality of the interface between the gate insulating film and the oxide semiconductor is improved.

1 . (canceled) 
     
     
         2 . An oxide semiconductor film, wherein:
 the oxide semiconductor film includes In, Ga, and Zn, and   a carrier concentration of the oxide semiconductor film is lower than 1×10 14 /cm 3 .   
     
     
         3 . The oxide semiconductor film according to  claim 2 , wherein hydrogen in the oxide semiconductor film is reduced, and then oxygen is introduced into a deficient portion from which the hydrogen is removed and an oxygen-deficient portion, whereby the carrier concentration of the oxide semiconductor film is lower than 1×10 14 /cm 3 . 
     
     
         4 . The oxide semiconductor film according to  claim 3 , wherein the hydrogen in the oxide semiconductor film is reduced by a heat treatment. 
     
     
         5 . The oxide semiconductor film according to  claim 2 , wherein a band gap of the oxide semiconductor film is 2 eV or more. 
     
     
         6 . The oxide semiconductor film according to  claim 3 , wherein the hydrogen in the oxide semiconductor film serves as a donor. 
     
     
         7 . A semiconductor device comprising:
 an oxide semiconductor film; and   an insulating film partly in contact with the oxide semiconductor film,   wherein:   the oxide semiconductor film includes In, Ga, and Zn,   a carrier concentration of the oxide semiconductor film is lower than 1×10 14 /cm 3 , and   the insulating film supplies oxygen to the oxide semiconductor film.   
     
     
         8 . The semiconductor device according to  claim 7 , wherein hydrogen in the oxide semiconductor film is reduced, and then oxygen is introduced into a deficient portion from which the hydrogen is removed and an oxygen-deficient portion, whereby the carrier concentration of the oxide semiconductor film is lower than 1×10 14 /cm 3 . 
     
     
         9 . The semiconductor device according to  claim 8 , wherein the hydrogen in the oxide semiconductor film is reduced by a heat treatment. 
     
     
         10 . The semiconductor device according to  claim 7 , wherein a band gap of the oxide semiconductor film is 2 eV or more. 
     
     
         11 . The semiconductor device according to  claim 8 , wherein the hydrogen in the oxide semiconductor film serves as a donor. 
     
     
         12 . A semiconductor device comprising:
 an oxide semiconductor film; and   an insulating film partly in contact with the oxide semiconductor film,   wherein:   the oxide semiconductor film includes In, Ga, and Zn,   a carrier concentration of the oxide semiconductor film is lower than 1×10 14 /cm 3 , and   an oxygen concentration of the insulating film is higher than that of the oxide semiconductor film.   
     
     
         13 . The semiconductor device according to  claim 12 , wherein hydrogen in the oxide semiconductor film is reduced, and then oxygen is introduced into a deficient portion from which the hydrogen is removed and an oxygen-deficient portion, whereby the carrier concentration of the oxide semiconductor film is lower than 1×10 14 /cm 3 . 
     
     
         14 . The semiconductor device according to  claim 13 , wherein the hydrogen in the oxide semiconductor film is reduced by a heat treatment. 
     
     
         15 . The semiconductor device according to  claim 12 , wherein a band gap of the oxide semiconductor film is 2 eV or more. 
     
     
         16 . The semiconductor device according to  claim 13 , wherein the hydrogen in the oxide semiconductor film serves as a donor.