Abstract: An ultraviolet-erasable nonvolatile semiconductor device has a protective film comprised of a silicon nitride film on which is laminated a silicon oxynitride film. The silicon nitride film has a thickness of 1000 ? or more and 2000 ? or less and the silicon oxynitride film has a thickness of about 7000 ? or more. The silicon nitride film and the silicon oxynitride film cooperate to prevent moisture from penetrating into the ultraviolet-erasable nonvolatile semiconductor device. The thickness of the silicon nitride film is set so that the time for erasing data in a nonvolatile semiconductor storage element through irradiation with ultraviolet rays is not increased.

Abstract: In order to provide an ultraviolet-erasable nonvolatile semiconductor device that has a high water resistance and is capable of erasing data by ultraviolet rays, a protective film includes a silicon nitride film (12) and a silicon oxynitride film (13). The silicon nitride film (12) and the silicon oxynitride film (13) cooperate to prevent moisture from penetrating into the ultraviolet-erasable nonvolatile semiconductor device. The silicon nitride film 12 has such a thickness with which a time for erasing data in a nonvolatile semiconductor storage element (17) through irradiation of the ultraviolet rays is not increased.