Patent ID: 7541233

Claim:
A method of manufacturing a semiconductor device, the device comprising: a semiconductor substrate; an isolation region provided on a surface of the semiconductor substrate and including an isolation trench; and a non-volatile memory cell provided on the semiconductor substrate, the non-volatile memory cell comprising: a tunnel insulating film including a portion whose thickness increases gradually toward the isolation region; a floating gate electrode provided on the tunnel insulating film; a control gate electrode above the floating gate electrode; and an interelectrode insulating film provided between the control gate electrode and the floating gate electrode, the method comprising: forming an insulating film to be processed into the tunnel insulating film on the semiconductor substrate; forming a semiconductor film to be processed into the floating gate electrode on the insulating film; forming the isolation trench by etching the semiconductor film, the insulating film, and the semiconductor substrate; and annealing the floating gate electrode, the tunnel insulating film, and the semiconductor substrate in an oxidizing atmosphere.