Method of forming self-aligned contact structure with locally etched gate conductive layer

Abstract

A method of forming a self-aligned contact structure with a locally etched conductive layer comprises the steps of: preparing a substrate formed with gate structures comprising a first conductive layer, a second conductive layer, and an insulating layer; depositing a photoresist material layer on the substrate; performing a lithographic step with a bit-line contact node photomask or a bit-line contact photomask to expose a portion of the surface of the substrate; etching the exposed second conductive layer with an etchant; removing the remaining photoresist material layer; forming a sidewall spacer on the sidewalls of each gate structure; forming a dielectric layer to cover the substrate; and performing lithographic and etching steps to remove the dielectric layer and to form self-aligned contact structure.

1 . A gate structure with a locally etched conductive layer, comprising: 
 (a) a semiconductor substrate;    (b) a first conductive layer formed on said substrate;    (c) a second conductive layer formed on said first conductive layer,    wherein a side of said second conductive layer, which is used to form a self-aligned contact window is locally etched; and    (d) an insulating layer formed on said second conductive layer.    
   
   
       2 . The gate structure with a locally etched conductive layer of  claim 1 , wherein said first conductive layer is selected from polysilicon and amorphous silicon.  
   
   
       3 . The gate structure with a locally etched conductive layer of  claim 1 , wherein said second conductive layer is a metal silicide.  
   
   
       4 . The gate structure with a locally etched conductive layer of  claim 1 , wherein said second conductive layer is a tungsten silicide.  
   
   
       5 . A self-aligned contact structure with a locally etched conductive layer, comprising: 
 (a) a semiconductor substrate;    (b) a plurality of separated gate structures formed on said substrate, wherein each gate structure comprises: 
 (i) a first conductive layer deposited on the surface of said substrate;  
 (ii) a second conductive layer deposited on the surface of said first conductive layer, wherein a side of said second conductive layer, which is used to form a self-aligned contact window is locally etched; and  
 (iii) an insulating layer deposited on the surface of said second conductive layer;  
   (c) a sidewall spacer formed on a sidewall of each gate structure;    (d) a dielectric layer that covers the side of each said gate structure, which is not used to form a self-aligned contact structure; and    (e) a metal layer that covers said dielectric, said sidewall spacers of each said gate structure and said substrate, wherein said metal layer is not in contact with said conductive layer.    
   
   
       6 . The self-aligned contact structure with a locally etched conductive layer of  claim 5 , wherein said first conductive layer is selected from polysilicon and amorphous silicon.  
   
   
       7 . The self-aligned contact structure with a locally etched conductive layer of  claim 5 , wherein said metal silicide layer is a metal silicide.  
   
   
       8 . The self-aligned contact structure with a locally etched conductive layer of  claim 7 , wherein said second conductive layer is a tungsten silicide.  
   
   
       9 . The self-aligned contact structure with a locally etched conductive layer of  claim 5 , wherein said insulating layer is a silicon nitride layer.  
   
   
       10 . The self-aligned contact structure with a locally etched conductive layer of  claim 5 , wherein said sidewall spacer is a silicon nitride layer.