Semiconductor device and its manufacturing method

Abstract

A semiconductor device and a method of manufacturing the semiconductor device are disclosed. A semiconductor device of one of several disclosed embodiments comprises a semiconductor layer having a source region and a drain region, and a gate insulating film provided on the semiconductor layer between the source region and the drain region. The gate insulating film comprising an oxide including a metal element and further includes at least one element selected from the group consisting of nitrogen and aluminum as a first element. The content of the first element is relatively higher at both ends near the source region and the drain region than at a center of the gate insulating film. A gate electrode is provided on the gate insulating film.

1 - 15 . (canceled)  
   
   
       16 . A semiconductor device comprising: 
 a semiconductor layer;    a gate insulating film provided on the semiconductor layer, the gate insulating film being made of an oxide including a metal element; a gate electrode provided on the gate insulating film;    a first oxide layer provided on a surface of the semiconductor layer surrounding the gate insulating film, the first oxide layer being made of an oxide of an element composing the semiconductor layer; and    a second oxide layer provided on a side surface of the gate electrode, the second oxide layer being made of an oxide of an element composing the gate electrode, a thickness of the second oxide layer being equal to or smaller than a thickness of the first oxide layer.    
   
   
       17 . A semiconductor device according to  claim 16 , wherein the metal element is an element selected from the group consisting of scandium, yttrium, zirconium, hafnium and lanthanoid elements.  
   
   
       18 . A method of manufacturing a semiconductor device comprising: 
 forming a first layer made of an oxide including a metal element on a semiconductor layer;    forming a second layer made of a conductive material on the first layer;    forming a gate electrode by selectively etching the second layer and forming a gate insulating film by selectively etching the first layer; introducing at least one element selected from the group consisting of nitrogen and aluminum from a side surface of the gate insulating film; and    forming an oxide layer on the side surface of the gate electrode.    
   
   
       19 . A method of manufacturing a semiconductor device according to  claim 18 , further comprising introducing at least one element selected from the group consisting of nitrogen and aluminum in a surface of the first layer before forming the second layer.  
   
   
       20 . A method of manufacturing a semiconductor device comprising: 
 forming a first layer made of an oxide including a metal element on a semiconductor layer;    forming a second layer made of a conductive material on the first layer;    forming a gate electrode by selectively etching the second layer;    forming a gate insulating film by selectively etching the first layer until the gate insulating film recesses from the gate electrode;    forming a material including at least one element selected from the group consisting of nitrogen and aluminum in the recess; and    forming an oxide layer on a side surface of the gate electrode.    
   
   
       21 . A method of manufacturing a semiconductor device according to  claim 20 , further comprising introducing at least one element selected from the group consisting of nitrogen and aluminum in a surface of the first layer before forming the second layer.  
   
   
       22 . A method of manufacturing a semiconductor device comprising: 
 forming a first layer made of an oxide including a metal element on a semiconductor layer;    forming a second layer made of a conductive material on the first layer;    forming a gate electrode by selectively etching the second layer and forming a gate insulating film by selectively etching the first layer; and    forming an oxide layer on a side surface of the gate electrode by exposing the side surface to an active oxygen.    
   
   
       23 . A method of manufacturing a semiconductor device according to  claim 21 , wherein the active oxygen is a radical of oxygen or an ion of oxygen.  
   
   
       24 . A method of manufacturing a semiconductor device according to  claim 21 , further comprising introducing at least one element selected from the group consisting of nitrogen and aluminum in a surface of the first layer before forming the second layer.