Semiconductor device or display device including the same

Abstract

To provide a novel method for manufacturing a semiconductor device. To provide a method for manufacturing a highly reliable semiconductor device at relatively low temperature. The method includes a first step of forming a first oxide semiconductor film in a deposition chamber and a second step of forming a second oxide semiconductor film over the first oxide semiconductor film in the deposition chamber. Water vapor partial pressure in an atmosphere in the deposition chamber is lower than water vapor partial pressure in atmospheric air. The first oxide semiconductor film and the second oxide semiconductor film are formed such that the first oxide semiconductor film and the second oxide semiconductor film each have crystallinity. The second oxide semiconductor film is formed such that the crystallinity of the second oxide semiconductor film is higher than the crystallinity of the first oxide semiconductor film.

1 . (canceled) 
     
     
         2 . A manufacturing method of a semiconductor device, comprising:
 a first step of forming a first oxide semiconductor film in a deposition chamber; and   a second step of forming a second oxide semiconductor film over the first oxide semiconductor film in the deposition chamber,   wherein a pressure in an atmosphere in the deposition chamber is from 1×10 −7  Pa to several hundreds Pa.   
     
     
         3 . The manufacturing method of a semiconductor device, according to  claim 2 ,
 wherein each of the first oxide semiconductor film and the second oxide semiconductor film is formed by a sputtering method.   
     
     
         4 . The manufacturing method of a semiconductor device, according to  claim 2 ,
 wherein the second oxide semiconductor film is formed in an atmosphere in which oxygen partial pressure is higher than oxygen partial pressure in an atmosphere in which the first oxide semiconductor film is formed.   
     
     
         5 . The manufacturing method of a semiconductor device, according to  claim 2 ,
 wherein the first oxide semiconductor film is formed with an oxygen flow rate ratio higher than or equal to 0% and lower than or equal to 30%, and   wherein the second oxide semiconductor film is formed with an oxygen flow rate ratio higher than 30% and lower than or equal to 100%.   
     
     
         6 . The manufacturing method of a semiconductor device, according to  claim 2 ,
 wherein the first oxide semiconductor film includes a nanocrystal, and   wherein the second oxide semiconductor film includes a c-axis-aligned crystal.   
     
     
         7 . The manufacturing method of a semiconductor device, according to  claim 2 ,
 wherein each of the first oxide semiconductor film and the second oxide semiconductor film is formed with an In-M-Zn oxide target, and   wherein the M is Ga, Al, Y, or Sn.   
     
     
         8 . The manufacturing method of a semiconductor device, according to  claim 7 ,
 wherein an atomic ratio of the In to the M and the Zn is In:M:Zn=4:2:4.1 or a neighborhood of In:M:Zn=4:2:4.1.   
     
     
         9 . The manufacturing method of a semiconductor device, according to  claim 7 ,
 wherein an atomic ratio of the In to the M and the Zn is In:M:Zn=5:1:7 or a neighborhood of In:M:Zn=5:1:7.   
     
     
         10 . The manufacturing method of a semiconductor device, according to  claim 7 ,
 wherein an atomic ratio of the In to the M and the Zn is In:M:Zn=1:1:1.2 or a neighborhood of In:M:Zn=1:1:1.2.   
     
     
         11 . A manufacturing method of a semiconductor device, comprising:
 a first step of heating a substrate in a deposition chamber;   a second step of forming a first oxide semiconductor film over the substrate in the deposition chamber; and   a third step of forming a second oxide semiconductor film over the first oxide semiconductor film in the deposition chamber,   wherein a pressure in an atmosphere in the deposition chamber is from 1×10 −7  Pa to several hundreds Pa.   
     
     
         12 . The manufacturing method of a semiconductor device, according to  claim 11 ,
 wherein each of the first oxide semiconductor film and the second oxide semiconductor film is formed by a sputtering method.   
     
     
         13 . The manufacturing method of a semiconductor device, according to  claim 11 ,
 wherein the second oxide semiconductor film is formed in an atmosphere in which oxygen partial pressure is higher than oxygen partial pressure in an atmosphere in which the first oxide semiconductor film is formed.   
     
     
         14 . The manufacturing method of a semiconductor device, according to  claim 11 ,
 wherein the first oxide semiconductor film is formed with an oxygen flow rate ratio higher than or equal to 0% and lower than or equal to 30%, and   wherein the second oxide semiconductor film is formed with an oxygen flow rate ratio higher than 30% and lower than or equal to 100%.   
     
     
         15 . The manufacturing method of a semiconductor device, according to  claim 11 ,
 wherein the first oxide semiconductor film includes a nanocrystal, and   wherein the second oxide semiconductor film includes a c-axis-aligned crystal.   
     
     
         16 . The manufacturing method of a semiconductor device, according to  claim 11 ,
 wherein each of the first oxide semiconductor film and the second oxide semiconductor film is formed with an In-M-Zn oxide target, and   wherein the M is Ga, Al, Y, or Sn.   
     
     
         17 . The manufacturing method of a semiconductor device, according to  claim 16 ,
 wherein an atomic ratio of the In to the M and the Zn is In:M:Zn=4:2:4.1 or a neighborhood of In:M:Zn=4:2:4.1.   
     
     
         18 . The manufacturing method of a semiconductor device, according to  claim 16 ,
 wherein an atomic ratio of the In to the M and the Zn is In:M:Zn=5:1:7 or a neighborhood of In:M:Zn=5:1:7.   
     
     
         19 . The manufacturing method of a semiconductor device, according to  claim 16 ,
 wherein an atomic ratio of the In to the M and the Zn is In:M:Zn=1:1:1.2 or a neighborhood of In:M:Zn=1:1:1.2.