| 摘要 |
<p>A method of manufacturing a GaAs semiconductor device of an enhancement/depletion, E/D, construction having a GaAs/AlGaAs heterojunction and using a two-dimensional electron gas, includes the steps of forming a heterojunction semiconductor substrate and etching a portion of the substrate to provide a gate portion of a depletion-mode FET DM. The substrate comprises a semi-insulating GaAs layer 1, an undoped GaAs layer 2, an N-type AlGaAs layer 4 forming an electron-supply layer, and a GaAs layer. The GaAs layer comprises a first GaAs layer 5, an etching stopping AlGaAs layer 6, and a second GaAs layer 7, with the first GaAs layer 5 being formed on the N-type GaAs layer 4. The etching step to provide the gate portion is preferably carried out by a dry etching method using an etchant of CCI2F2 gas, so that the second GaAs layer 7 is etched but the AlGaAs layer 6 is not etched. Thus, the thickness of the layers between a gate electrode 19GD of the depletion-mode FET, DM and the GaAs 5 AlGaAs 4 hetero- junction plane is determined during the formation of the heterojunction substrate, so that a better uniformity of the threshold voltage of depletion-mode FET DM is obtained.</p> |
