Method of fabricating flash memory device

Abstract

A method of fabricating a flash memory which increases a coupling ratio between a floating gate and a control gate in a cell. The method comprises sequentially forming a tunnel oxide film, and polysilicon and first insulation films for a floating gate on an active area of a semiconductor substrate; forming a photoresist as a mask on the first insulation film, and performing an etching process using the photoresist as the mask; forming a hard mask by depositing a second insulation film for prevention of oxidation on the semiconductor substrate; forming an STI by using the hard mask; oxidizing sidewalls of the STI and gap-filling the STI; forming a floating gate by removing the second insulation film remaining as the hard mask; and sequentially forming an ONO film and a control gate on the floating gate.

1 - 15 . (canceled) 
   
   
       16 . A flash memory device comprising:
 a floating gate including a tunnel oxide film and a polysilicon film on an active area of a semiconductor substrate;   an STI wherein the sidewalls of the STI are oxidized in an oxide-oxidization method, and then the STI is gap-filled to prevent forming voids therein; and   an ONO film and a control gate sequentially formed on the floating gate.   
   
   
       17 . The flash memory device of  claim 16 , wherein the floating gate is larger than the tunnel oxide film in size of area, to obtain a coupling ratio between the floating gate and the control gate. 
   
   
       18 . The flash memory device of  claim 16 , wherein the tunnel oxide film has a thickness between approximately 30 Å and approximately 300 Å. 
   
   
       19 . The flash memory device of  claim 16 , wherein the flash memory device has an ETOX (EPROM Thin Oxide) cell structure. 
   
   
       20 . The flash memory device of  claim 16 , wherein a top surface of the tunnel oxide film and a bottom surface of the floating gate are coplanar across substantially their entire area.