Semiconductor device

Abstract

A transistor in which a short-channel effect is not substantially caused and which has switching characteristics even in the case where the channel length is short is provided. Further, a highly integrated semiconductor device including the transistor is provided. A short-channel effect which is caused in a transistor including silicon is not substantially caused in the transistor including an oxide semiconductor film. The channel length of the transistor including the oxide semiconductor film is greater than or equal to 5 nm and less than 60 nm, and the channel width thereof is greater than or equal to 5 nm and less than 200 nm. At this time, the channel width is made 0.5 to 10 times as large as the channel length.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 an oxide semiconductor film including a channel region;   a gate electrode overlapping with the oxide semiconductor film; and   a gate insulating film between the gate electrode and the oxide semiconductor film,   wherein a channel length is greater than or equal to 5 nm and less than 60 nm, and a channel width is greater than or equal to 5 nm and less than 200 nm.   
     
     
         2 . The semiconductor device according to  claim 1 , further comprising an interlayer insulating film having low oxygen permeability over the oxide semiconductor film and the gate electrode. 
     
     
         3 . The semiconductor device according to  claim 1 ,
 wherein the gate insulating film is in contact with at least part of a side surface of the oxide semiconductor film.   
     
     
         4 . The semiconductor device according to  claim 1 ,
 wherein the gate insulating film includes at least a first layer and a second layer, and   wherein the second layer has lower oxygen permeability than the first layer.   
     
     
         5 . The semiconductor device according to  claim 4 ,
 wherein the second layer is an aluminum oxide film.   
     
     
         6 . The semiconductor device according to  claim 4 ,
 wherein the first layer contains excess oxygen, and is in contact with the oxide semiconductor film.   
     
     
         7 . The semiconductor device according to  claim 1 ,
 wherein the channel width is 0.5 to 10 times as large as the channel length.   
     
     
         8 . The semiconductor device according to  claim 1 ,
 wherein the oxide semiconductor film is a CAAC-OS film.   
     
     
         9 . The semiconductor device according to  claim 1 ,
 wherein the oxide semiconductor film contains at least In.   
     
     
         10 . The semiconductor device according to  claim 1 ,
 wherein the oxide semiconductor film contains at least In, Ga, and Zn.   
     
     
         11 . The semiconductor device according to  claim 1 , further comprising a base insulating film, wherein the base insulating film, the oxide semiconductor film, the gate insulating film, and the gate electrode are stacked in this order. 
     
     
         12 . The semiconductor device according to  claim 11 , wherein the base insulating film contains excess oxygen. 
     
     
         13 . A semiconductor device comprising:
 a first transistor comprising:
 an oxide semiconductor film in contact with a pair of electrodes; 
 a first gate electrode overlapping with the oxide semiconductor film; and 
 a gate insulating film between the first gate electrode and the oxide semiconductor film; 
   a second transistor comprising a second gate electrode; and   a capacitor comprising:
 one of the pair of electrodes; and 
 a capacitor electrode overlapping with the one of the pair of electrodes, 
   wherein the second gate electrode and the one of the pair of electrodes are electrically connected to each other, and   wherein a channel length of the first transistor is greater than or equal to 5 nm and less than 60 nm, and a channel width of the first transistor is greater than or equal to 5 nm and less than 200 nm.   
     
     
         14 . The semiconductor device according to  claim 13 ,
 wherein the gate insulating film is in contact with at least part of a side surface of the oxide semiconductor film.   
     
     
         15 . The semiconductor device according to  claim 13 , further comprising a barrier film including a layer having low oxygen permeability over the oxide semiconductor film and the first gate electrode. 
     
     
         16 . The semiconductor device according to  claim 13 ,
 wherein the gate insulating film includes at least a first layer and a second layer, and   wherein the first layer has lower oxygen permeability than the second layer.   
     
     
         17 . The semiconductor device according to  claim 16 ,
 wherein the second layer is an aluminum oxide film.   
     
     
         18 . The semiconductor device according to  claim 16 ,
 wherein the first layer contains excess oxygen, and is in contact with the oxide semiconductor film.   
     
     
         19 . The semiconductor device according to  claim 13 ,
 wherein the second transistor includes a channel region containing silicon.   
     
     
         20 . The semiconductor device according to  claim 13 ,
 wherein the first transistor and the second transistor are provided in different layers,   wherein a hydrogen-containing layer and a layer containing excess oxygen are provided between the first transistor and the second transistor,   wherein the hydrogen-containing layer is closer to the second transistor than the layer containing excess oxygen, and   wherein a hydrogen concentration in the hydrogen-containing layer measured by secondary ion mass spectrometry is 1×10 21  atoms/cm 3  or more.   
     
     
         21 . The semiconductor device according to  claim 20 ,
 wherein the hydrogen-containing layer is a silicon nitride oxide film or a silicon nitride film.   
     
     
         22 . The semiconductor device according to  claim 20 , further comprising a layer having low hydrogen permeability between the hydrogen-containing layer and the layer containing excess oxygen. 
     
     
         23 . The semiconductor device according to  claim 13 ,
 wherein the channel width is 0.5 to 10 times as large as the channel length.   
     
     
         24 . The semiconductor device according to  claim 13 ,
 wherein the oxide semiconductor film is a CAAC-OS film.   
     
     
         25 . The semiconductor device according to  claim 13 ,
 wherein the oxide semiconductor film contains at least In.   
     
     
         26 . The semiconductor device according to  claim 13 ,
 wherein the oxide semiconductor film contains at least In, Ga, and Zn.   
     
     
         27 . The semiconductor device according to  claim 13 ,
 wherein an off-state current of the first transistor is lower than 1×10 −21  A per micrometer of the channel width at room temperature.   
     
     
         28 . The semiconductor device according to  claim 13 ,
 wherein the oxide semiconductor film, the gate insulating film, and the second gate electrode are stacked in this order.