Semiconductor device and method of manufacturing the same

Abstract

A semiconductor device includes at least one interlevel insulating film, a storage electrode, a capacitor insulating film, a plate electrode, and a protective film. The interlevel insulating film is arranged on a semiconductor substrate. The storage electrode is made of a metal material and arranged on the interlevel insulating film. The capacitor insulating film is made of an insulating metal oxide and arranged on the storage electrode. The plate electrode is made of tungsten nitride and arranged on the capacitor insulating film. The protective film is arranged on the plate electrode to suppress outward diffusion of nitrogen from the plate electrode. A method of manufacturing the semiconductor device is also disclosed.

What is claimed is:  
     
         1 . A semiconductor device comprising: 
 at least one interlevel insulating film arranged on a semiconductor substrate;    a first electrode made of a metal material and arranged on said interlevel insulating film;    a capacitor insulating film made of an insulating metal oxide and arranged on said first electrode;    a second electrode made of tungsten nitride and arranged on said capacitor insulating film; and    a protective film arranged on said second electrode to suppress outward diffusion of nitrogen from said second electrode.    
     
     
         2 . A device according to  claim 1 , wherein said protective film is made of a metal silicide.  
     
     
         3 . A device according to  claim 2 , wherein said protective film is made of tungsten silicide.  
     
     
         4 . A device according to  claim 1 , wherein said protective film is made of silicon nitride.  
     
     
         5 . A device according to  claim 1 , wherein a transistor is arranged on said semiconductor substrate under said interlevel insulating film.  
     
     
         6 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming at least one interlevel insulating film on a semiconductor substrate;    forming a first electrode made of a metal material on the interlevel insulating film;    forming a capacitor insulating film made of an insulating metal oxide on the first electrode;    forming a second electrode made of tungsten nitride, formed by thermal chemical vapor deposition, on the capacitor insulating film; and    forming a protective film on the second electrode to suppress outward diffusion of nitrogen from the second electrode.    
     
     
         7 . A method according to  claim 6 , wherein the protective film is made of a metal silicide.  
     
     
         8 . A method according to  claim 7 , wherein the protective film is made of tungsten silicide.  
     
     
         9 . A method according to  claim 6 , wherein the protective film is made of silicon nitride.  
     
     
         10 . A method according to  claim 6 , wherein the protective film is formed by thermal chemical vapor deposition using at least silicon source gas.  
     
     
         11 . A method according to  claim 6 , wherein a tungsten nitride film and a silicon-containing thin film are continuously formed on the semiconductor substrate on which the capacitor insulating film has been formed, and the tungsten nitride film and the silicon-containing thin film are processed to form the second electrode and the protective film.