JPS577164A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the thickness of source and drain electrodes from being locally reduced, wire disconnection in the electrodes and the migration of electrode material by a method wherin the side of an active layer is formed in the shape of a taper continuous to a portion of the surface of a buffer layer. CONSTITUTION:A buffer layer 2 without the addition of Cr and an N type active layer 3 are formed on semi-insulated GaAs 1 with Cr by the epitaxial method, and SiO2 14 is provided. Photoresist 15 is employed as a mask, while the active layer 3 is mesa-etched. Etching in the transverse direction is stopped at about the end portion of SiO2 14 and that in the vertical direction is stopped when the surface of the buffer layer 2 has been etched by the specified thickness. As a result, the side face becomes taper-shaped. After this, the conventional method is used to develop and expand electrodes 17, 18 made of Au-Ge alloy from the upper face of the active layer 3 to its side so as to make the electrodes extend up to the buffer layer 2, and the electrodes are covered with SiO2 19, before being provided with an Al gate electrode 20 to complete the manufacturing process. With this construction, the yield and reliability of the device are improved, while the leakage current via the buffer layer is minimized, thereby improving its high frequency characteristics.