Method for manufacturing semiconductor device

Abstract

A semiconductor device including an oxide semiconductor with stable electric characteristics and high reliability is provided. An island-shaped oxide semiconductor layer is formed by using a resist mask, the resist mask is removed, oxygen is introduced (added) to the oxide semiconductor layer, and heat treatment is performed. The removal of the resist mask, introduction of the oxygen, and heat treatment are performed successively without exposure to the air. Through the oxygen introduction and heat treatment, impurities such as hydrogen, moisture, a hydroxyl group, or hydride are intentionally removed from the oxide semiconductor layer, whereby the oxide semiconductor layer is highly purified. Chlorine may be introduced to an insulating layer over which the oxide semiconductor layer is formed before formation of the oxide semiconductor layer. By introducing chlorine, hydrogen in the insulating layer can be fixed, thereby preventing diffusion of hydrogen from the insulating layer into the oxide semiconductor layer.

1 . (canceled) 
     
     
         2 . A method for manufacturing a semiconductor device comprising:
 forming an oxide semiconductor film containing indium, gallium and zinc;   forming a metal oxide over the oxide semiconductor film; and   introducing oxygen into the oxide semiconductor film from above the metal oxide,   wherein the metal oxide contains at least one metal element included in the oxide semiconductor film.   
     
     
         3 . The method for manufacturing a semiconductor device according to  claim 2 , wherein the metal oxide has a thickness of greater than or equal to 10 nm and less than or equal to 200 nm. 
     
     
         4 . A method for manufacturing a semiconductor device comprising:
 forming an oxide semiconductor film containing indium, gallium and zinc;   forming a metal oxide over the oxide semiconductor film; and   introducing oxygen into the oxide semiconductor film from above the metal oxide,   wherein the metal oxide contains at least one metal element included in the oxide semiconductor film, and   wherein an amount of oxygen introduced into the oxide semiconductor film is larger than an amount of hydrogen contained in the oxide semiconductor film.   
     
     
         5 . The method for manufacturing a semiconductor device according to  claim 4 , wherein the metal oxide has a thickness of greater than or equal to 10 nm and less than or equal to 200 nm. 
     
     
         6 . A method for manufacturing a semiconductor device comprising:
 forming an oxide semiconductor film containing indium, gallium and zinc;   forming a metal oxide over the oxide semiconductor film; and   introducing oxygen into the oxide semiconductor film from above the metal oxide,   heating the oxide semiconductor film and the metal oxide to dehydrate or dehydrogenate the oxide semiconductor film,   wherein the metal oxide contains at least one metal element included in the oxide semiconductor film, and   wherein an amount of oxygen introduced into the oxide semiconductor film is larger than an amount of hydrogen contained in the oxide semiconductor film subjected to the dehydration or dehydrogenation.   
     
     
         7 . The method for manufacturing a semiconductor device according to  claim 6 , wherein the metal oxide has a thickness of greater than or equal to 10 nm and less than or equal to 200 nm. 
     
     
         8 . A method for manufacturing a semiconductor device comprising:
 forming a gate insulating film;   forming an oxide semiconductor film containing indium, gallium and zinc over the gate insulating film;   forming a metal oxide over the oxide semiconductor film; and   introducing oxygen into the oxide semiconductor film from above the metal oxide,   wherein the metal oxide contains a same material as the gate insulating film, and   wherein an amount of oxygen introduced into the oxide semiconductor film is larger than an amount of hydrogen contained in the oxide semiconductor film.   
     
     
         9 . The method for manufacturing a semiconductor device according to  claim 8 , wherein the metal oxide has a thickness of greater than or equal to 10 nm and less than or equal to 200 nm.