| 摘要 |
PURPOSE:To enable to obtain a deep recess in a semiconductor device by a method wherein an anodizing liquid is heated at the specified temperature, and thickness of a high impurity concentration region is unified by using a variable current circuit in a dark condition. CONSTITUTION:A semiinsulating buffer layer, and a GaAs layer are grown epitaxially in order on a semiinsulating GaAs substrate. Then the wafer 10 is set in an anodizing tank 11. The temperature of the anodizing liquid is set previously at 50 deg.C+ or -30 deg.C. A heater 12 is used for that purpose, and a mixed liquid of ethylene glycol, water and tartaric acid is used as the anodizing liquid, for example. A dark box is covered on the anodizing tank to make the tank to be in a dark condition, and an electric power source 13 is used to perform anodizing. Initial anodizing current density is made to 1mA/cm<2>. Anodizing is performed by advancing anodizing, and at the point in time when an oxidizing current value becomes to 1/20 of an initial current value, it is judged as unification completed time. After anodizing in the dark condition is finished, formation of a recess is performed according to the photoresist method. |
