JPS5737886A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a highly reliable Schottky barrier diode by increasing the impurity concentration of an Si layer gradually or by stages thicknesswise. CONSTITUTION:First, an N type first epitaxial layer 2 is laid on an N<+> type substrate 1 doped with Sb and subsequently, an N type second epitaxial layer is thereon at a relatively low concentration. A metal 4 such as Al is piled thereon. The concentration of the epitaxial layer is varied gradually with the growth temperature and conditions of the subsequent heat treatment. First and second epitaxial layers both doped with an impurity hard to diffuse by heat are laid on the substrate one upon another and finally, a low temperature epitaxial layer is laid thereon so that the concentration may be changed by stages. With such an arrangement, a sharp concentration gradient is eliminated between the layers. This relaxes the capacitive action of the epitaxial layers, namely, inductive action between the metal layer and the substrate thereby removing the concentration of the electric field during the operation. Accordingly, the electrostatic breakdown strength can be increased sufficiently thereby providing a highly reliable Schottky barrier diode.