| 摘要 |
PURPOSE:To remove only a GaAs layer with sufficient selectivity without damaging an AlGaAs layer by heating the GaAs layer to temperature higher than Ga is exfoliated from the layer surface while emitting an As molecular beam in high vacuum to remove the GaAs layer. CONSTITUTION:A mask 7 with a hole formed at a gate electrode forming region of an enhancement mode element is formed on its semiconductor substrate, and it is etched in depth which arrives at an N-type GaAs layer 4. Then, the mask 7 is formed with a hole in the gate electrode forming region of a depletion mode element. The substrate is cleaned, mounted, for example, in an MBE growing unit, which is evacuated in approx. 10<-10>Torr, an As molecular beam is emitted thereto to heat it to approx. 750 deg.C in an As atmosphere of approx. 10<-8>-10<-7>Torr. Thus, the layer 4 is thermally etched in the gate electrode forming region, and an N-type GaAs layer 6 is thermally etched in the gate electrode forming region of the depletion mode element to expose an N-type AlGaAs layer 3 or N-type AlGaAs layer 5, and stopped. Thus, the GaAs layer on the A GaAs layer can be removed with sufficient selectively without damaging the substrate.
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