Semiconductor device and manufacturing method thereof

Abstract

An object is to suppress conducting-mode failures of a transistor that uses an oxide semiconductor film and has a short channel length. A semiconductor device includes a gate electrode 304, a gate insulating film 306 formed over the gate electrode, an oxide semiconductor film 308 over the gate insulating film, and a source electrode 310 a and a drain electrode 310 b formed over the oxide semiconductor film. The channel length L of the oxide semiconductor film is more than or equal to 1 μm and less than or equal to 50 μm. The oxide semiconductor film has a peak at a rotation angle 2θ in the vicinity of 31° in X-ray diffraction measurement.

1 . A semiconductor device comprising:
 an oxide semiconductor layer,   wherein a length of a channel formed in the oxide semiconductor layer is more than or equal to 1 μm and less than or equal to 50 μm, and   wherein a diffraction intensity of the oxide semiconductor layer in X-ray diffraction measurement has a peak at a rotation angle 2θ of more than or equal to 30° and less than or equal to 32°.   
     
     
         2 . The semiconductor device according to  claim 1  further comprising:
 a gate electrode; 
 a gate insulating layer over the gate electrode; and 
 a source electrode and a drain electrode over the oxide semiconductor layer, 
 wherein the oxide semiconductor layer is over the gate insulating layer. 
 
     
     
         3 . The semiconductor device according to  claim 1 , wherein the length of the channel is less than 5 μm. 
     
     
         4 . The semiconductor device according to  claim 1 , wherein a band gap of the oxide semiconductor layer is more than or equal to 3.1 eV. 
     
     
         5 . The semiconductor device according to  claim 1 , wherein the oxide semiconductor layer includes at least one oxide selected from the group consisting of indium oxide, zinc oxide, gallium oxide, tin oxide and a combination thereof. 
     
     
         6 . The semiconductor device according to  claim 1 , wherein the oxide semiconductor layer is an In—Ga—Zn-based oxide semiconductor layer. 
     
     
         7 . The semiconductor device according to  claim 1 ,
 wherein the oxide semiconductor layer includes a crystal part, and   wherein a c-axis of the crystal part is aligned in a direction substantially parallel to a normal vector of a surface on which the oxide semiconductor layer is formed.   
     
     
         8 . A semiconductor device comprising:
 an oxide semiconductor layer,   wherein a length of a channel formed in the oxide semiconductor layer is more than or equal to 1 μm and less than or equal to 50 μm,   wherein the oxide semiconductor layer includes a crystal part, and   wherein a c-axis of the crystal part is aligned in a direction substantially parallel to a normal vector of a surface on which the oxide semiconductor layer is formed.   
     
     
         9 . The semiconductor device according to  claim 8  further comprising:
 a gate electrode; 
 a gate insulating layer over the gate electrode; and 
 a source electrode and a drain electrode over the oxide semiconductor layer, 
 wherein the oxide semiconductor layer is over the gate insulating layer. 
 
     
     
         10 . The semiconductor device according to  claim 8 , wherein the length of the channel is less than 5 μm. 
     
     
         11 . The semiconductor device according to  claim 8 , wherein the oxide semiconductor layer is an In—Ga—Zn-based oxide semiconductor layer. 
     
     
         12 . The semiconductor device according to  claim 1  further comprising:
 a substrate; and 
 a base insulating film between the substrate and the oxide semiconductor layer. 
 
     
     
         13 . The semiconductor device according to  claim 12 , wherein the base insulating film is one of a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film and an aluminum oxide film. 
     
     
         14 . The semiconductor device according to  claim 13 ,
 wherein the base insulating film is the aluminum oxide film, and   wherein a density of the aluminum oxide film is 3.2 g/cm 3  or more.   
     
     
         15 . The semiconductor device according to  claim 13 ,
 wherein the base insulating film is the aluminum oxide film, and   wherein an amount of water (H 2 O) released from the aluminum oxide film is less than or equal to 5×10 15  atoms/cm 3 .   
     
     
         16 . The semiconductor device according to  claim 13 ,
 wherein the base insulating film is the aluminum oxide film, and   wherein an amount of hydrogen (H 2 ) released from the aluminum oxide film is less than or equal to 5×10 15  atoms/cm 3 .