<p>A semiconductor device comprising a substrate, a laminate including a multilayer interconnection structure formed on the substrate, a moisture-resistant ring extending continuously in the laminate to surround an element region where an active element is formed, and a protective trench formed on the outside of the moisture-resistant ring in the laminate continuously along the moisture-resistant ring in such a manner that the surface of the substrate is exposed. The laminate consists of a lamination of interlayer insulating films having a dielectric constant lower than that of an SiO<SUB>2</SUB> film; the upper surface of the laminate and the sidewall face and the bottom surface of the protective trench are covered continuously with a protective film including at least a silicon nitride film excepting an electrode pad on the multilayer interconnection structure; and an interface film mainly composed of Si and C is formed between the protective film and the sidewall face of the protective trench.</p>
