Semiconductor device and manufacturing method thereof

Abstract

The interval between gate electrodes in a memory cell portion and the interval between gate electrodes in a peripheral circuit portion are set so as to have a relation with the widths of sidewall insulating films of the gate electrodes. Using an etching stopper film, first only a memory cell contact hole is selectively formed and a silicon film is filled at the bottom. As a result, an optimum electrode structure can be each provided on an n type diffusion layer in the memory cell portion and an n type diffusion layer in the peripheral circuit portion.

What is claimed is:  
     
         1 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming first and second diffusion layers on a surface of a semiconductor substrate;    forming an interlayer insulating film on said semiconductor substrate including said first and second diffusion layers;    forming first and second openings in a region of the interlayer insulating film on said first diffusion layer and a region of the interlayer insulating film on said second diffusion layer, respectively to expose surfaces of said first and second diffusion layers;    depositing a conductive silicon film on said semiconductor substrate;    etching back said conductive silicon film to form a lower portion of a first plug in a lower portion of said first opening while at the same time removing the conductive silicon film at the bottom of said second opening to expose a surface of said second diffusion layer; and    depositing a metal film on said semiconductor substrate including said first and second openings, filling said first and second openings with said metal film to form an upper portion of said first plug on said lower conductive silicon plug in said first opening while at the time filling said metal film in said second opening to form a second plug.    
     
     
         2 . The method of manufacturing a semiconductor device according to  claim 1 , wherein said depositing said metal film comprises the steps of: 
 depositing a barrier metal film on said semiconductor substrate including said first and second openings; and    depositing a metal film lapped on said barrier metal film.    
     
     
         3 . The method of manufacturing a semiconductor device according to  claim 1 , wherein the opening width of said first opening is smaller than twice the thickness of said conductive silicon film; and the opening width of said second opening is larger than twice the thickness of said conductive silicon film.  
     
     
         4 . The method of manufacturing a semiconductor device according to  claim 1 , wherein said conductive silicon film is of one kind selected from the group consisting of a polysilicon film, an amorphous silicon film, an epitaxially grown film, and a silicon-germanium compound crystal film.  
     
     
         5 . The method of manufacturing a semiconductor device according to  claim 1 , wherein said conductive silicon film is an amorphous silicon film, and further comprising the step of reforming said amorphous silicon film into a polysilicon film after filling said second opening with said metal film.  
     
     
         6 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming first and second diffusion layers on a surface of a semiconductor substrate;    forming an interlayer insulating film on said semiconductor substrate including said first and second diffusion layers;    forming a first opening in a region of the interlayer insulating film on said first diffusion layer to expose a surface of said first diffusion layer;    depositing a conductive silicon film to fill a lower portion of said first opening with said conductive silicon film, thereby forming a lower portion of a first plug;    depositing an upper metal film to fill an upper portion of said first opening with said upper metal film, thereby forming an upper portion of said first plug;    forming a second opening in a region of the interlayer insulating film on said second diffusion layer to expose a surface of said second diffusion layer; and    depositing a metal film on said semiconductor substrate including said second opening to fill said second opening with said metal film, thereby forming a second plug.    
     
     
         7 . The method of manufacturing a semiconductor device according to  claim 6 , wherein said filling said first opening with the conductive silicon film comprises the steps of: 
 depositing the conductive silicon film on said semiconductor substrate including said first opening; and    etching back said conductive silicon film.    
     
     
         8 . The method of manufacturing a semiconductor device according to  claim 6 , wherein said depositing said upper metal film filled within said first opening and said metal film filled within said second opening comprise the steps of: 
 depositing a barrier metal film on said semiconductor substrate including said first and second openings; and    depositing a metal film lapped on said semiconductor including said first and second openings.    
     
     
         9 . The method of manufacturing a semiconductor device according to  claim 6 , wherein said conductive silicon film is of one kind selected from the group consisting of a polysilicon film, an amorphous silicon film, an epitaxially grown film and a silicon-germanium compound crystal film.  
     
     
         10 . The method of manufacturing a semiconductor device according to  claim 6 , wherein said conductive silicon film is an amorphous silicon film, and further comprising the step of reforming said amorphous silicon film into a polysilicon film after filling said second opening with said metal film.  
     
     
         11 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming first and second diffusion layers on a surface of a semiconductor substrate;    forming an interlayer insulating film on said semiconductor substrate including said first and second diffusion layers;    forming first and second openings in a regions in the interlayer insulating film on said first and second diffusion layers, respectively and exposing only a surface of said first diffusion layer;    depositing a conductive silicon film to fill a lower portion of said first opening with the conductive silicon film, thereby forming a lower portion of a first plug;    exposing a surface of said second diffusion layer at the bottom of said second opening; and    depositing a metal film on said semiconductor substrate including said first and second openings, filling an upper portion of said first opening with said metal film to form an upper portion of said first plug, while at the same time filling said second opening with said metal film to form a second plug.    
     
     
         12 . The method of manufacturing a semiconductor device according to  claim 11 , wherein said depositing said metal film on said semiconductor substrate including said first and second openings comprises the steps of: 
 depositing a barrier metal film on said semiconductor substrate including said first and second openings; and    depositing a metal film lapped on said semiconductor including said first and second openings.    
     
     
         13 . The method of manufacturing a semiconductor device according to  claim 11 , wherein said conductive silicon film is of one kind selected from the group consisting of a polysilicon film, an amorphous silicon film, an epitaxially grown film and a silicon-germanium compound crystal film.  
     
     
         14 . The method of manufacturing a semiconductor device according to  claim 11 , wherein said conductive silicon film is an amorphous silicon film, and further comprising the step of reforming said amorphous silicon film into a polysilicon film after filling said second opening with said metal film.  
     
     
         15 . The method of manufacturing a semiconductor device according to  claim 11 , further comprising the steps of: 
 forming a sidewall insulating film at a sidewall of a gate electrode before forming said interlayer insulating film; and    forming an etching stopper film on said sidewall insulating film.    
     
     
         16 . The method of manufacturing a semiconductor device according to  claim 15 , wherein said forming said first and second openings and exposing only a surface of said first diffusion layer comprises the step of allowing said etching stopper film positioned at said second opening to remain.  
     
     
         17 . The method of manufacturing a semiconductor device according to  claim 15 , wherein said sidewall insulating film is a film to protect a side surface of said gate electrode, the opening width of said first opening is smaller than twice the thickness of said sidewall insulating film and the opening width of said second opening is larger than twice the thickness of said sidewall insulating film.  
     
     
         18 . The method of manufacturing a semiconductor device according to  claim 16 , wherein said exposing a surface of the second diffusion layer at said second opening is executed by removing said etching stopper film positioned at said second opening.  
     
     
         19 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming first and second gate electrodes on a semiconductor substrate, the distance between said first gate electrodes being narrow than the distance between said second gate electrodes;    forming a first sidewall insulating film at sidewalls of said first and second gate electrodes;    forming a first diffusion layer on said semiconductor substrate using said first gate electrode and said first sidewall insulating film as a mask and forming a second diffusion layer on said semiconductor substrate using said second gate electrode and said first sidewall insulating film as a mask;    forming a second sidewall insulating film on said first sidewall insulating film;    depositing an etching stopper film;    forming an interlayer insulating film on said etching stopper film;    etching said interlayer insulating film, said etching stopper film and said first and second sidewall insulating film so as to form a first opening in a region on said first diffusion layer exposing a surface of said first diffusion layer and a second opening in a region on said second diffusion layer exposing said etching stopper film;    depositing a conductive silicon film to fill a lower portion of said first opening with the conductive silicon film, thereby forming a lower portion of a first plug;    removing said etching stopper film at the bottom of said second opening to expose a surface of said second diffusion layer; and    depositing a metal film on said semiconductor substrate including said first and second openings, filling an upper portion of said first opening with said metal film to form an upper portion of said first plug in said first opening while at the same time filling said second opening with said metal film to form a second plug in said second opening.    
     
     
         20 . The method of manufacturing a semiconductor device according to  claim 19 , wherein said conductive silicon film is of one kind selected from the group consisting of a polysilicon film, an amorphous silicon film, an epitaxially grown film, and a silicon-germanium compound crystal film.  
     
     
         21 . The method of manufacturing a semiconductor device according to  claim 19 , wherein said conductive silicon film is an amorphous silicon film, and further comprising the step of reforming said amorphous silicon film into a polysilicon film after filling said second opening with said metal film.