| 摘要 |
PURPOSE:To prevent a gate electrode metal from coming into contact with a 2DEG layer at the edge of a mesa so as to avoid a gate leakage by a method wherein Al contained in an electron supply layer is made to increase gradually in a mol ratio starting from the surface of the layer and terminating at its other surface on a substrate side, and the layer is selectively etched with a mixed gas of chlorine and halogen gas. CONSTITUTION:An impurity-undoped GaAs layer 2 is made to grow on a semi-insulating GaAs substrate 1, and in succession an impurity-doped AlxGa1-xAs layer 4 is formed in such a state that Al contained in the layer 4 is made to decrease in stages in a mol ratio x starting from its surface on a substrate side and terminating at its other surface. Then, a mesa etching is carried out for the purpose of an element isolation, and an electron supply layer which forms quantum fine lines is etched at the same time. The etching process is stopped at a specified point inside an impurity-doped AlGaAs layer depending on the mol ratio of Al contained impurity-diped AlGaAs layers 3a-3b. A selective etching is carried out with a mixed gas of chlorine and fluorine using a reactive ion etching method. In succession, a source electrode metal 6 and a drain electrode metal 7 are formed using resist of AuGe/Ni/Au through an evaporation lift-off method, and thus the ohmic electrodes are formed of alloy. A channel part is split into fine lines at the formation of the ohmic electrodes 6 and 7. |
