Semiconductor device manufacture method and semiconductor device

Abstract

A semiconductor device manufacturing method includes: forming a first active region and a second active region in a semiconductor substrate; forming a first gate insulating film on the first active region and a second gate insulating film thinner than the first gate insulating film on the second active region by using material containing silicon oxide; forming first and second gate electrodes on the first and second gate insulating films respectively; forming an insulating film on the semiconductor substrate, and anisotropically etching the insulating film to leave first side wall insulating films on side walls of the first and second gate electrodes; removing the first side wall insulating film on the first gate electrode; and after removing the first side wall insulating film on the first gate electrode, thermally treating in an oxidizing atmosphere the semiconductor substrate to form a second side wall insulating film on the first gate electrode.

1 .- 6 . (canceled) 
     
     
         7 . A semiconductor device comprising:
 a semiconductor substrate;   an element isolation insulating film for defining first and second active regions in the semiconductor substrate;   a first gate insulating film formed on the first active region, having a first film thickness and containing silicon oxide;   a second gate insulating film formed on the second active region, having a second film thickness thinner than the first film thickness and containing silicon oxide;   a first gate electrode formed on the first gate insulating film and containing polysilicon;   a second gate electrode formed on the second gate insulating film and containing polysilicon;   a first side wall insulating film formed on side wall of the first gate electrode and made of silicon oxide formed through oxidization of the side wall of the first gate electrode; and   a second side wall insulating film formed on side wall of the second gate electrode.   
     
     
         8 . The semiconductor device according to  claim 7 , wherein the second side wall insulating film covers a side end of the second gate insulating film. 
     
     
         9 . The semiconductor device according to  claim 7 , wherein the second side wall insulating film is made of silicon nitride.