A method for preventing the formation of recesses in the surface of a borophosphosilicate glass layer comprising the step of first forming a borophosphosilicate glass layer over a substrate, then forming a silicon nitride film having a thickness of about 300.ANG. to 1000.ANG. over the borophosphosilicate glass layer. Next, contact windows are formed, followed by cleaning with an RCA solution. The silicon nitride film provides a protective function preventing the formation of recesses on the borophosphosilicate glass surface. Consequently, no short-circuiting metal bridges caused by metal in the recesses after the deposition of metallic conducting wires are formed.