| 摘要 |
PURPOSE:To ensure base width under a guard ring, and keep breakdown strength at a specified value, by making the contact surface of a metal layer forming a Schottky barrier of a semiconductor substrate lower than the surface of the guard ring around the contact surface. CONSTITUTION:The surface of an n-layer 1 with which a Schottky barrier metal layer 4 comes into contact is made lower than the region around the contact part. A p-layer 6 of the guard ring part bridges both step-differences. For example, the n-layer 1 is stacked on an n<+> silicon substrate 2 of high impurity concentration by epitaxial growth method. The impurity concentration of the n-layer is 5X10<15>/cm<2> and the thickness is 6mum. From the surface of the n-layer 1, acceptor impurity ions are selectively implanted, and a guard ring part 6, 3mum deep, doped with acceptor impurity is formed by heat treatment. A window is opened in an oxide film 3 formed on the surface, and an exposed silicon surface is etched as far as the depth which does not reach the diffusion depth of the p-layer 6, by using mixed liquid of hydrofluoric acid, nitric acid and acetic acid. |
