Abstract: An improved semiconductor device having no posioned via produced therein includes a semiconductor substrate having a first conductor pattern formed thereon, a first insulator film provided on the semiconductor substrate to cover the first conductor pattern, and a coat applied onto the first insulator film to flatten an uneven surface of the first insulator film. A nitride layer having a thickness of 10.ANG. or more and including a binding of silicon and nitrogen is provided in a surface of the coat. A second insulator film is formed on the coat including the nitride layer. A via hole for exposing a portion of the surface of the first conductor pattern is formed to penetrate the first insulator film, the coat and the second insulator film. The device further includes a second conductor pattern having a portion thereof buried in the via hole and thereby connected to the first conductor pattern.