| 摘要 |
PURPOSE:To enable to form in high accuracy an active region in the thickness with which the prescribed threshold voltage will be obtained by a method wherein a dry etching is performed on the surface of the active region of FET. CONSTITUTION:A non-doped GaAs layer 2, an AlxGa1-xAs layer 3 having the impurity density of 10<18>cm<-3>, and a GaAs layer 4 having the impurity density of 10<18>cm<-3> with the film thickness of several hundreds Angstrom are provided successively on a semiinsulating GaAs substrate 1. Besides, a source electrode 5 and a drain electrode 6 are formed on the GaAs layer 4, and a back gate electrode 7 made of material consisting of gold- germanium (AuGe) and gold (Au) are formed on the rear face of the substrate 1. When the value of gate threshold voltage is set, at -0.4V, for example, the voltage of -40V can be applied between the source electrode 5 and the back gate electrode 7. A semiconductor device is provided using the ordinary reactive ion-etching device consisting of a double electrode construction as an etching device in the state wherein -40V is applied to the power source located between the source electrode 5 and the back gate electrode 7 and 2-5V is applied to the power source E1 located between the source electrode 5 and the drain electrode 6. When the process of etching is in progress on the active region 8, the current between the source electrode 5 and the drain electrode 6 is turned to zero at a certain point of time. |
