Semiconductor memory device comprising magneto resistive element and its manufacturing method

Abstract

A semiconductor memory device including a memory cell having a first ferromagnetic film, a tunnel barrier film formed on the first ferromagnetic film, and a second ferromagnetic film formed on the tunnel barrier film, the tunnel barrier film having a larger film thickness in its in-surface edge portion than in its in-surface central portion, a side wall insulating film formed so as to surround at least sides of the second ferromagnetic film, and an interlayer insulating film formed so as to cover the memory cell and the side wall insulating film.

1 . A semiconductor memory device comprising: 
 a memory cell comprising a first ferromagnetic film, a tunnel barrier film formed on the first ferromagnetic film, and a second ferromagnetic film formed on the tunnel barrier film, the tunnel barrier film having a larger film thickness in its in-surface edge portion than in its in-surface central portion;    a side wall insulating film formed so as to surround at least sides of the second ferromagnetic film; and    an interlayer insulating film formed so as to cover the memory cell and the side wall insulating film.    
     
     
         2 . A semiconductor memory device comprising: 
 a memory cell comprising a first ferromagnetic film, a tunnel barrier film formed on the first ferromagnetic film, and a second ferromagnetic film formed on the tunnel barrier film, the tunnel barrier film having a larger film thickness in its in-surface edge portion than in its in-surface central portion; and    a side wall insulating film formed so as to surround at least sides of the second ferromagnetic film and containing a metal element.    
     
     
         3 . A semiconductor memory device comprising: 
 a memory cell comprising a first ferromagnetic film, a tunnel barrier film formed on the first ferromagnetic film, and a second ferromagnetic film formed on the tunnel barrier film, the tunnel barrier film having a larger film thickness in its in-surface edge portion than in its in-surface central portion; and    a side wall insulating film formed on the tunnel barrier film so as to surround a periphery of the second ferromagnetic film.    
     
     
         4 . A semiconductor memory device comprising: 
 a memory cell comprising a first ferromagnetic film, a tunnel barrier film formed on the first ferromagnetic film and containing oxygen elements, and a second ferromagnetic film formed on the tunnel barrier film, the tunnel barrier film having a larger tunnel resistance per unit area in its in-surface edge portion than in its in-surface central portion, the tunnel barrier film having a larger film thickness in its in-surface edge portion than in its in-surface central portion.    
     
     
         5 . The device according to  claim 4 , wherein the tunnel barrier film contains in its in-surface edge portion a magnetic metal element contained in at least one of the first and second magnetic films.  
     
     
         6 . The device according to  claim 4 , wherein the tunnel barrier film is formed of aluminum oxide.