Manufacture of compound semiconductor device

PURPOSE:To prevent the deterioration of the characteristics of a compound semiconductor device in a step of forming the electrode of GaAsFET, for example, by forming in advance an insulating film on the surface of a substrate, removing an insulating film of the region forming the electrode, then forming the electrode metal, and thus protecting the surface of the substrate. CONSTITUTION:In the step of manufacturing, for example, a GaAs Schottky gate FET, an SiO2 film 3 is formed on a substrate 1 formed with an active layer 2. Then, a resist layer 4 is formed, the films 3 of the source and the drain regions are removed, an electrode material is deposited, is lifted off, and an electrode 6 is formed. Then, a resist layer 7 opened at the gate electrode region is formed, an SiO2 film 3 is similarly removed, a gate metal is then deposited, is lifted off, a gate electrode 9 is then formed, and an element is completed. Thus, the surface of the substrae can be treated with medicine or with cleaning or the like by protecting the surface. Accordingly, the characteristics of the element, e.g., noise index, power gain, etc. can be improved.