Mos transistor in an active region

Abstract

After an isolation region is formed using a field-forming silicon nitride film, this silicon nitride film is patterned, thereby a gate trench is formed. Next, a gate electrode material is buried into the gate trench, and this is etched back. Thereafter, the silicon nitride is removed, thereby a contact hole is formed. A contact plug is buried into this contact hole. With this arrangement, the contact plug can be formed without using a diffusion layer contact pattern. At the same time, the periphery of the contact plug substantially coincides with a boundary between the element isolation region and the active region. Accordingly, the active region can be reduced.

1 - 6 . (canceled)  
   
   
       7 . A method of manufacturing a semiconductor device, comprising: 
 a first step for forming a field-forming insulation film having a predetermined pattern on a semiconductor substrate;    a second step for forming an isolation region using the field-forming insulation film;    a third step for forming a gate trench by patterning at least the field-forming insulation film;    a fourth step for burying at least a gate electrode into the gate trench;    a fifth step for forming a contact hole by removing the field-forming insulation film; and    a sixth step for burying a contact plug into the contact hole.    
   
   
       8 . The method of manufacturing a semiconductor device as claimed in  claim 7 , wherein said second step includes: 
 a first sub-step for forming an isolation trench on the semiconductor substrate using the field-forming insulation film as a mask; and    a second sub-step for burying a dielectric material into the isolation trench.    
   
   
       9 . The method of manufacturing a semiconductor device as claimed in  claim 7 , wherein said fourth step includes: 
 a third sub-step for forming a sidewall made of a dielectric material on a side surface of the gate trench;    a fourth sub-step for burying a conductive material into the gate trench; and    a fifth sub-step for forming the gate electrode by removing an unnecessary portion of the conductive material.    
   
   
       10 . The method of manufacturing a semiconductor device as claimed in  claim 9 , wherein said conductive material is removed so that the upper surface of the gate electrode becomes lower than the upper surface of the field-forming insulation film in the fifth sub-step.  
   
   
       11 . The method of manufacturing a semiconductor device as claimed in  claim 9 , wherein a dielectric material that constitutes the sidewall is different from a material of the field-forming insulation film.  
   
   
       12 . The method of manufacturing a semiconductor device as claimed in  claim 9 , wherein said fourth step further includes a sixth sub-step of forming a cap made of a dielectric material on an upper surface of the gate electrode.  
   
   
       13 . The method of manufacturing a semiconductor device as claimed in  claim 12 , wherein 
 at the sixth sub-step, after a dielectric film that covers the field-forming insulation film and the gate electrode is formed, the dielectric film is polished until when an upper surface of the field-forming insulation film is exposed.    
   
   
       14 . The method of manufacturing a semiconductor device as claimed in  claim 12 , wherein a dielectric material that constitutes the cap is different from a material of the field-forming insulation film.  
   
   
       15 . The method of manufacturing a semiconductor device as claimed in  claim 7 , wherein a material of the field-forming insulation film is silicon nitride.  
   
   
       16 . The method of manufacturing a semiconductor device as claimed in  claim 11 , wherein a material of the field-forming insulation film is silicon nitride.  
   
   
       17 . The method of manufacturing a semiconductor device as claimed in  claim 16 , wherein a material of the sidewall is silicon oxide.  
   
   
       18 . The method of manufacturing a semiconductor device as claimed in  claim 14 , wherein a material of the field-forming insulation film is silicon nitride.  
   
   
       19 . The method of manufacturing a semiconductor device as claimed in  claim 18 , wherein a material of the cap is silicon oxide.