OHMIC ELECTRODE FORMING METHOD IN COMPOUND SEMICONDUCTOR

PURPOSE:To provide ohmic electrode with small contact resistance and high reproductivity, by a method wherein on a compound semiconductor crystal with P as main constituent element is formed a high-melting metal layer at a low temperature, and Au layer is formed on the uppermost layer, and then the heat treatment is performed at such temperature and time that the Au layer and the semiconductor crystal do not react to produce alloy. CONSTITUTION:In order to form electrodes in alignment with buried layers 202, 203 and a cap layer 207, an insulation film layer 208 from SiO2 film is formed on a surface, and part of the insulation layer 208 is bored and then a first metal layer 209 is formed by means of vacuum evaporation. A second metal layer 210 of Mo, Pt or the like is formed thereon, and further a third metal layer 211 of Au is formed thereon. The second metal layer 210 is interposed between the first metal layer 209 and the third metal layer 211 of Au used to facilitate the bonding and serves to prevent reaction during the heat treatment. In this constitution, ohmic electrode with good reproductivity and small contact resistance is obtained.