Transistor, and display device, electronic device, and semiconductor device using the same

Abstract

It is an object of an invention disclosed in the present specification to provide a transistor having low contact resistance. In the transistor, a semiconductor film including an impurity element imparting P-type or N-type conductivity, an insulating film formed thereover, and an electrode or a wiring that is electrically connected to the semiconductor film through a contact hole formed at least in the insulating film are included; the semiconductor film has a first range of a concentration of the impurity element (1×10 20 /cm 3 or less) that is included in a deeper region than predetermined depth, and a second range of a concentration of the impurity element (more than 1×10 20 /cm 3 ) that is included in a shallower region than the predetermined depth; and a deeper region than a portion in contact with the electrode or the wiring in the semiconductor film is in the first range of the concentration of the impurity element.

1 . A transistor comprising: 
 a semiconductor film including an impurity element imparting P-type or N-type conductivity;    an insulating film formed over the semiconductor film; and    an electrode or a wiring that is electrically connected to the semiconductor film through a contact hole formed at least in the insulating film,    wherein the semiconductor film has a first range of a concentration of the impurity element that is included in a deeper region than predetermined depth, and a second range of a concentration of the impurity element that is included in a shallower region than the predetermined depth, which has a higher concentration than the first range, and    wherein a deeper region than a portion in contact with the electrode or the wiring in the semiconductor film is in the first range of the concentration of the impurity element.    
   
   
       2 . A transistor according to  claim 1 , wherein the impurity element is phosphorus, and the semiconductor film is a film containing silicon as its main component.  
   
   
       3 . A transistor according to  claim 1 , wherein the first range is set to be 1×10 20 /cm 3  or less, and the second range is set to be more than 1×10 20 /cm 3  and 1×10 21 /cm 3  or less.  
   
   
       4 . A liquid crystal display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 1 .    
   
   
       5 . An electroluminescence display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 1 .    
   
   
       6 . An electronic device in which a liquid crystal display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 1 .    
   
   
       7 . An electronic device in which an electroluminescence display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 1 .    
   
   
       8 . A semiconductor device using a transistor described in  claim 1 .  
   
   
       9 . A wireless IC tag using a transistor described in  claim 1 .  
   
   
       10 . A transistor comprising: 
 a source region and a drain region including an impurity element imparting P-type or N-type conductivity;    an insulating film formed over the source region and the drain region; and    an electrode or a wiring that is electrically connected to one of the source region and the drain region through a contact hole formed at least in the insulating film,    wherein the source region and the drain region have a first range of a concentration of the impurity element that is included in a deeper region than predetermined depth, and a second range of a concentration of the impurity element that is included in a shallower region than the predetermined depth, which has a higher concentration than the first range, and    wherein a deeper region than a portion in contact with the electrode or the wiring in one of the source region and the drain region is in the first range of the concentration of the impurity element.    
   
   
       11 . A transistor according to  claim 10 , wherein the impurity element is phosphorus, and the source region and the drain region are formed in a silicon substrate.  
   
   
       12 . A transistor according to  claim 10 , wherein the first range is set to be 1×10 20 /cm 3  or less, and the second range is set to be more than 1×10 20 /cm 3  and 1×10 21 /cm 3  or less.  
   
   
       13 . A liquid crystal display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 10 .    
   
   
       14 . An electroluminescence display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 10 .    
   
   
       15 . An electronic device in which a liquid crystal display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 10 .    
   
   
       16 . An electronic device in which an electroluminescence display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 10 .    
   
   
       17 . A semiconductor device using a transistor described in  claim 10 .  
   
   
       18 . A wireless IC tag using a transistor described in  claim 10 .  
   
   
       19 . A transistor comprising: 
 a semiconductor film in which a source region and a drain region including an impurity element imparting P-type or N-type conductivity is formed;    an insulating film formed over the semiconductor film; and    an electrode or a wiring that is electrically connected to one of the source region and the drain region through a contact hole formed at least in the insulating film,    wherein the source region and the drain region have a first range of a concentration of the impurity element that is included in a deeper region than predetermined depth, and a second range of a concentration of the impurity element that is included in a shallower region than the predetermined depth, which has a higher concentration than the first range,    wherein a first region that is deeper than a portion in contact with the electrode or the wiring in one of the source region and the drain region is in the first range of the concentration of the impurity element, and    wherein a thickness of the first region is thinner than a thickness of a second region except for the first region in one of the source region and the drain region, and 50% of a thickness of the second region as a lower limit.    
   
   
       20 . A transistor according to  claim 19 , wherein the impurity element is phosphorus, and the semiconductor film is a film containing silicon as its main component.  
   
   
       21 . A transistor according to  claim 19 , wherein the first range is set to be 1×10 20 /cm 3  or less, and the second range is set to be more than 1×10 20 /cm 3  and 1×10 21 /cm 3  or less.  
   
   
       22 . A liquid crystal display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 19 .    
   
   
       23 . An electroluminescence display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 19 .    
   
   
       24 . An electronic device in which a liquid crystal display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 19 .    
   
   
       25 . An electronic device in which an electroluminescence display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 19 .    
   
   
       26 . A semiconductor device using a transistor described in  claim 19 .  
   
   
       27 . A wireless IC tag using a transistor described in  claim 19 .  
   
   
       28 . A transistor comprising: 
 a semiconductor film including an impurity element imparting P-type or N-type conductivity;    an insulating film formed over the semiconductor film; and    an electrode or a wiring that is electrically connected to the semiconductor film through a contact hole formed at least in the insulating film,    wherein the semiconductor film comprises a first region and a second region having a higher impurity concentration than the first region, the first region being deeper than the second region, and    wherein the second region of the semiconductor film just under the electrode or the wiring is thinner than a portion of the second region, the portion being not under the electrode or the wiring.    
   
   
       29 . A transistor according to  claim 28 , wherein the impurity element is phosphorus, and the semiconductor film is a film containing silicon as its main component.  
   
   
       30 . A transistor according to  claim 28 , wherein a concentration of the impurity element in the first region is set to be 1×10 20 /cm 3  or less, and a concentration of the impurity element in the second region is set to be more than 1×10 20 /cm 3  and 1×10 21 /cm 3  or less.  
   
   
       31 . A liquid crystal display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 28 .    
   
   
       32 . An electroluminescence display device using a thin film transistor at least in a pixel, 
 wherein the thin film transistor is a transistor described in  claim 28 .    
   
   
       33 . An electronic device in which a liquid crystal display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 28 .    
   
   
       34 . An electronic device in which an electroluminescence display device using a thin film transistor at least in a pixel is mounted, 
 wherein the thin film transistor is a transistor described in  claim 28 .    
   
   
       35 . A semiconductor device using a transistor described in  claim 28 .  
   
   
       36 . A wireless IC tag using a transistor described in  claim 28.