Semiconductor device and method of fabricating the same

Abstract

A method of fabricating a semiconductor device comprising a semiconductor substrate, a gate insulating film formed on the semiconductor substrate, a conductive layer formed on the insulating film, and an etch-stop insulating film formed within the conductive layer to stop etching.

1 . A method of fabricating a semiconductor device comprising:
 (1) forming a gate insulating film on a semiconductor substrate;   (2) forming a first polycrystalline silicon layer on the gate insulating film so that a recess is formed;   (3) forming a first insulating film on a surface of the first polycrystalline silicon layer;   (4) forming and flattening a second polycrystalline silicon layer so that the recess formed in the first polycrystalline silicon layer is buried in the second polycrystalline silicon layer;   (5) forming a second insulating film on the second polycrystalline silicon layer flattened by (4) or the first insulating film, wherein the second insulating film is made of a material differing from one for the first insulating film;   (6) forming an etched film on the second insulating film formed by (5);   (7) etching the etched film so that a surface of the second insulating film is exposed;   (8) eliminating the exposed second insulating film; and   (9) etching the first polycrystalline silicon layer.   
   
   
       2 . The method according to  claim 1 , wherein the second polycrystalline silicon layer is formed so as to cover the first insulating film and then flattened in (4), and a surface of the second polycrystalline silicon layer is oxidated by a heat treatment, thereby forming the second insulating film in (5). 
   
   
       3 . The method according to  claim 1 , wherein in (4), the second polycrystalline silicon layer is formed so as to cover the first insulating film and the second polycrystalline silicon layer is etched back by an RIE process so as to be flattened, and in (5), the second insulating film is formed on the second polycrystalline silicon layer flattened by (4). 
   
   
       4 . The method according to  claim 1 , wherein in (4), the second polycrystalline silicon layer is formed so as to cover the first insulating film and the second polycrystalline silicon layer is etched back by an RIE process so as to be flattened, and in (5), a surface of the second polycrystalline silicon layer formed in (4) so as to cover the second insulating film is oxidated by a heat treatment, thereby forming the second insulating film in (5). 
   
   
       5 . The method according to  claim 1 , wherein in (5), the second insulating film is formed so that a film thickness of the first insulating film is prevented from varying. 
   
   
       6 . The method according to  claim 1 , wherein in (5), the second insulating film is formed so that a film thickness of the first insulating film is prevented from varying. 
   
   
       7 . The method according to  claim 1 , wherein an ONO film is formed as the first insulating film in (3). 
   
   
       8 . The method according to  claim 2 , wherein an ONO film is formed as the first insulating film in (3). 
   
   
       9 . The method according to  claim 1 , wherein the first insulating film is etched under a high selective etching condition. 
   
   
       10 . The method according to  claim 1 , which is applied to a method of fabricating a non-volatile memory.