Method of making a MOS transistor

Abstract

A method of making a MOS transistor is disclosed. The disclosed techniques can completely transform a polysilicon gate electrode into a metal silicide electrode through a brief thermal treatment process by extending the contact area between the polysilicide gate electrode and a metal layer prior to a formation of a metal silicide. The disclosed MOS transistor fabricating method comprises providing a semiconductor substrate further comprising a polysilicon gate electrode with a silicide layer thereon, a spacer, and source and drain regions with LDD regions; forming an insulating layer on the area of the substrate; polishing the insulating layer so that the top of the polysilicon gate electrode can be exposed; etching some part of the insulating layer and the spacer so that both lateral walls of the polysilicon gate electrode can be exposed; forming a metal layer on the substrate resulted from the preceding step so that the polysilicon gate electrode can be covered with the metal layer; and transforming completely the polysilicon gate electrode into a metal silicide gate electrode by performing a thermal treatment process.

1 . A MOS transistor comprising: 
 a gate oxide;    a spacer; and    a gate electrode including a top and lateral walls, wherein the top and some part of lateral walls are exposed.    
   
   
       2 . A MOS transistor as defined by  claim 7 , wherein said gate electrode is fully silicided.  
   
   
       3 . A MOS transistor as defined by  claim 7  further comprising a metal layer comprising transition metals and their alloys, said metal layer being formed on a surface of said gate electrode.  
   
   
       4 . A MOS transistor as defined by claim  9 , wherein said gate electrode is fully silicided.  
   
   
       5 . A MOS transistor as defined by claim  9 , wherein said metal layer has a thickness between about 500 Å and about 1000 Å.  
   
   
       6 . A MOS transistor as defined by claim  9 , wherein said metal layer comprises one or more of Ti/TiN, Co/TiN and Co/Ti/TiN.  
   
   
       7 . A MOS transistor as defined by claim  12 , wherein said metal layer has a thickness between about 500 Å and about 1000 Å.