Nonvolatile semiconductor memory device and method of manufacturing the same

Abstract

Using a rapid thermal oxidation device, the top and side surfaces of a floating gate electrode are oxidized by In Situ Steam Generation (ISSG), wherein oxygen to which about 0.5 to 33% hydrogen has been added is introduced directly into a chamber with a temperature of approximately 900 to 1100° C. and a pressure of approximately 1,000 to 2,000 Pa, in order to generate water vapor from the introduced hydrogen and oxygen on a heated semiconductor substrate. Thus, an insulating film made of silicon oxide is formed on the surface of the floating gate electrode.

1 . A nonvolatile semiconductor memory device comprising: 
 a floating gate electrode that is formed on a semiconductor substrate with a first insulating film interposed between them and that is in an electrically floating state; and    a control gate electrode that is formed on the floating gate electrode with a second insulating film interposed between them, and that supplies a predetermined electric potential to the semiconductor substrate and the floating gate electrode;    wherein the first insulating film has a substantially uniform thickness at a portion where it is opposition to the floating gate electrode.    
   
   
       2 . The nonvolatile semiconductor memory device according to  claim 1 , wherein the control gate electrode is formed from a top surface of the floating gate electrode, along a side surface thereof, and to the semiconductor substrate next to that side surface, and with a third insulating film interposed between it and the top of the semiconductor substrate.  
   
   
       3 . The nonvolatile semiconductor memory device according to  claim 2 , wherein the first insulating film and the third insulating film are formed through identical processes.  
   
   
       4 . The nonvolatile semiconductor memory device according to  claim 2 , wherein the second insulating film and the third insulating film are formed through identical processes.  
   
   
       5 - 8 . (Cancelled).  
   
   
       9 . The nonvolatile semiconductor memory device according to  claim 1 , wherein the second insulating film is directly formed on an upper portion and side portions of the floating gate electrode, and 
 the control gate electrode is directly formed on the second insulating film.