| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of a step produced by mesa etching by providing a specific oxidized AlGaAs layer between a buffer layer and an active layer and reducing the parasitic capacitance, thereby eliminating decrease in the resistance in the buffer layer. SOLUTION: A recess G having flat bottom is formed in the surface of a high resistance silicon substrate 1 by anisotropic etching, for example, using a mask 2 of an insulating film. The mask 2 is then removed and thin films 3-6 of a compound semiconductor are grown heteroepitaxially on the entire surface of the substrate 1 and the surface is polished to expose and planarize the Si surface at the upper part of a terrace. Subsequently, an AlxGa1-xAs layer 4 is oxidized to obtain an AlxGa1-xAs layer (0.9<=x<=1) oxide layer 4'. Thereafter, an insulation film 8 is formed on the entire surface and subjected to continuous etching, including a contact layer 6 and a part of an active layer 5 using a mask for gate pattern. Finally, a gate metal film 9 is formed, the insulation film 8 is removed through patterning and a source/drain metal 10 is deposited.
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