Abstract: The method of fabricating a semiconductor nonvolatile storage device of this invention includes the steps of: forming an element region and an element isolation region on a semiconductor substrate; forming a memory gate insulation film by sequentially layering a tunnel oxide film, a silicon nitride film and a top oxide film on the device region; forming a memory gate electrode on the memory gate insulation film; forming heavily doped diffusion regions at element region portions self-aligned on opposite sides of the memory gate electrode; forming an interlayer insulator over the whole surface of the semiconductor substrate; forming contact holes in the interlayer insulator; forming interconnections passing through the contact holes and connecting with the memory gate electrode and the heavily doped diffusion regions; forming a passivating film over the whole surface of the semiconductor substrate including the interconnections by the plasma chemical vapor deposition process; forming openings for input/output t