PURPOSE: To prevent an external impurity from being introduced thereby to obtain a semiconductor device of high reliability by covering the sectional exposed part of 2-layer protecting layer of PSG and Si3N4 of a junction pad with an Si3N4 film having excellent moisture resistance.

CONSTITUTION: A P-type layer 2 and an N-type layer 3 are formed on an N-type Si substrate, a window is opened at a PSG 4, and an electrode and a junction pad are attached by an aluminum alloy 5. Then, a window is opened to be smaller than the pad by superposing it on a PSG 6, Si3N4 6 is then superposed by a plasma vapor growth method with SiH4 and NH4, and the window is reduced smaller. Stresses to the wirings and the electrodes are alleviated by the PSG, a defect of large moisture absorption is supplemented by the Si3N4 to prevent an external impurity from being introduced, thereby providing a semiconductor device of high reliability.