Semiconductor device having a ferroelectric capacitor

Abstract

A ferroelectric capacitor includes a lower electrode, a ferroelectric capacitor insulation film formed on the lower electrode and an upper electrode formed on the ferroelectric capacitor insulation film, wherein the ferroelectric capacitor insulation film has a composition of PZT and contains an excess amount of Pb with respect to a stoichiometry of PZT.

What is claimed is  
     
         1 . A ferroelectric capacitor, comprising: 
 a lower electrode;    a ferroelectric capacitor insulation film having a perovskite structure provided on said lower electrode, said ferroelectric capacitor insulation film containing therein Pb, Zr and Ti; and    an upper electrode provided on said ferroelectric capacitor insulation film, said upper electrode Including a conductive oxide layer having a perovskite structure,    wherein said ferroelectric capacitor insulation film contains an excess amount of Pb with respect to a stoichiometry composition of said ferroelectric capacitor insulation film.    
     
     
         2 . A ferroelectric capacitor as claimed In  claim 1 , wherein said ferroelectric capacitor insulation film contains Pb, in terms of a Pb/(Zr+Ti) ratio, of about 1.04-1.12.  
     
     
         3 . A ferroelectric capacitor as claimed In  claim 1 , wherein said ferroelectric capacitor insulation film contains Pb, in terms of a Pb/(Zr+Ti) ratio, of about 1.07-1.09.  
     
     
         4 . A ferroelectric capacitor, comprising: 
 a lower electrode;    a ferroelectric capacitor insulation film provided on said lower electrode; and    an upper electrode provided on said ferroelectric capacitor insulation film, said upper electrode including a conductive oxide layer having a perovskite structure provided on said ferroelectric capacitor insulation film,    said conductive oxide layer having a composition of SrRuO 3  and a thickness of about 30 nm or less.    
     
     
         5 . A ferroelectric capacitor, comprising: 
 a lower electrode;    a ferroelectric capacitor insulation film having a perovskite structure provided on said lower electrode, said ferroelectric capacitor insulation film containing Pb, Zr and Ti; and    an upper electrode provided on said ferroelectric capacitor insulation film, said upper electrode including a conductive oxide layer having a perovskite structure,    said ferroelectric capacitor insulation film having a thickness of about 300 nm or less.    
     
     
         6 . A semiconductor device, comprising: 
 a substrate;    an active element formed on said substrate; and    a ferroelectric capacitor formed on said substrate in electrical connection with said active element, said ferroelectric capacitor comprising: 
 a lower electrode;  
 a ferroelectric capacitor insulation film having a perovskite structure provided on said lower electrode, said ferroelectric capacitor insulation film containing therein Pb, Zr and Ti; and  
 an upper electrode provided on said ferroelectric capacitor insulation film, said upper electrode including a conductive oxide layer having a perovskite structure,  
 wherein said ferroelectric capacitor insulation film contains an excess amount of Pb with respect to a stoichiometry composition of said ferroelectric capacitor insulation film.  
   
     
     
         7 . A semi conductor device as claimed in  claim 6 , wherein said ferroelectric capacitor insulation film contains Pb, in terms of a Pb/(Zr+Ti) ratio, of about 1.04-1.12.  
     
     
         8 . A semiconductor device as claimed in  claim 6 , wherein said ferroelectric capacitor insulation film contains Pb, in terms of a Pb/(Zr+Ti) ratio, of about 1.07-1.09.  
     
     
         9 . A semiconductor device, comprising: 
 a substrate;    an active element formed on said substrate; and    a ferroelectric capacitor formed on said substrate in electrical connection with said active element, said ferroelectric capacitor comprising: 
 a lower electrode;  
 a ferroelectric capacitor insulation film provided on said lower electrode; and  
 an upper electrode provided on said ferroelectric capacitor insulation film, said upper electrode including a conductive oxide layer having a perovskite structure provided on said ferroelectric capacitor insulation film,  
 said conductive oxide layer having a composition of SrRuO 3  and a thickness of about 30 nm or less.  
   
     
     
         10 . A semiconductor device, comprising: 
 a substrate;    an active element formed on said substrate; and    a ferroelectric capacitor formed on said substrate in electrical connection with said active element, said ferroelectric capacitor comprising: 
 a lower electrode;  
 a ferroelectric capacitor insulation film having a perovskite structure provided on said lower electrode, said ferroelectric capacitor insulation film containing Pb, Zr and Ti; and  
 an upper electrode provided on said ferroelectric capacitor insulation film, said upper electrode including a conductive oxide layer having a perovskite structure,  
 said ferroelectric capacitor insulation film having a thickness of about 300 nm or less.  
   
     
     
         11 . A method of fabricating a semiconductor device having a ferroelectric capacitor, comprising the steps of: 
 depositing a lower electrode on a substrate;    forming a ferroelectric capacitor insulation film on said lower electrode;    forming an upper electrode of an oxide layer having a perovskite structure; and    applying, after said step of forming said upper electrode, an annealing process at a temperature of about 600° C. or more.    
     
     
         12 . A method as claimed in  claim 11 , wherein said ferroelectric capacitor insulation film has a perovskite structure and containing Pb, Zr and Ti, said ferroelectric capacitor insulation film containing an excess amount of Pb with respect to a stoichiometry composition thereof.  
     
     
         13 . A method as claimed in  claim 9 , wherein said ferroelectric capacitor insulation film contains Pb, in terms of a Pb/(Zr+Ti) ratio, of about 1.04-1.12.  
     
     
         14 . A method as claimed in  claim 9 , wherein said ferroelectric capacitor insulation film contains Pb, in terms of a Pb/(Zr+Ti) ratio, of about 1.07-1.09.