Abstract: A semiconductor device having a protective insulating film is disclosed. This semiconductor device includes a semiconductor substrate, and an interconnection pattern provided on said semiconductor substrate and electrically connected with said elements. A silicon-oxy-nitride film is provided on said semiconductor substrate so as to cover said interconnection pattern. The silicon-oxy-nitride film is deposited in accordance with a chemical vapor deposition Method using plasma, using a mixture gas including organic silane and a nitriding gas and has therefore superior step coverage. The silicon-oxy-nitride film has a superior barrier characteristic to moisture coming in from the outside. A semiconductor device superior in reliability such as moisture resistance is thus obtained.