Ultraviolet-erasable nonvolatile semiconductor device
View Patent ↗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 Å or more and 2000 Å or less and the silicon oxynitride film has a thickness of about 7000 Å 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.
1. An ultraviolet-erasable nonvolatile semiconductor device, comprising:
a semiconductor substrate;
an ultraviolet-erasable nonvolatile semiconductor storage element formed in a surface of the semiconductor substrate;
a top metal formed on the semiconductor substrate; and
a protective film formed on the ultraviolet-erasable nonvolatile semiconductor storage element and the top metal, the protective film comprising a first silicon nitride film, a silicon oxynitride film laminated thereon, a thickness of the silicon oxynitride film being thicker than that of the first silicon nitride film, and a second silicon nitride film laminated on the silicon oxynitride film.
2. An ultraviolet-erasable nonvolatile semiconductor device according to claim 1 , wherein the first silicon nitride film has a thickness of 1,000 Å or more and 2,000 Å or less.
3. An ultraviolet-erasable nonvolatile semiconductor device according to claim 1 , wherein the silicon oxynitride film has a refractive index of from 1.65 to 1.85.
4. An ultraviolet-erasable nonvolatile semiconductor device according to claim 1 , wherein the silicon oxynitride film has a thickness of about 7000 Å or more.
5. An ultraviolet-erasable nonvolatile semiconductor device according to claim 4 , wherein the first silicon nitride film has a thickness of 1,000 Å or more and 2,000 Å or less.
6. An ultraviolet-erasable nonvolatile semiconductor device according to claim 5 , wherein the silicon oxynitride film has a refractive index of from 1.65 to 1.85.