To provide a semiconductor device having a gate oxide film for preventing the leakage of charge, and a method for manufacturing the semiconductor device.

This semiconductor device contains fluorine that is introduced to an oxide film at the side of a floating gate 5. The fluorine combines with silicon in the side-wall oxide film of the floating gate 5 or a lower-side tunnel oxide film or the unpaired bond of oxygen, and forms Si-F bond or Si-O-F bond. The bond is strong, thus preventing the elimination of fluorine even if electrical stress is applied, preventing the generation of charge trap, and hence preventing the leakage of the charge that is retained by the floating gate 5 to the outside.