| 摘要 |
PURPOSE:To perform selective etching between the compounds in a compound semiconductor, by forming an oxide film or a nitride film with O2 plasma or N2 plasma on the surfaces of an AlxGa1-xAs layer and a GaAs layer, and performing etching with alkali solution. CONSTITUTION:At first, selective etching of a GaAs layer 2 in the present invention using, e.g., oxygen plasma through a hole 8, which is provided in a mask pattern 1. The thickness reduction is stopped directly over an AlGaAs film 3. Then, the thickness reduction of the AlGaAs film 3 and opening of a hole in the mask pattern 1 are performed by etching using HF aqueous solution. Then, the selective etching based on the present invention is performed again for a GaAs film 4 and also for a GaAlAs film 5, which is to become a secondary electron supplying layer. The thickness reduction is stopped directly over the GaAlAs film 5, which is to become the secondary electron supplying layer. An electrode is formed thereon, and an E/D-HEMT is completed. The high selectivity of this etching makes it possible to reproduce the design value of the thickness of the GaAlAs 1a film 5, which is to become the secondary electron-gas supplying layer accurately.
|
