| 摘要 |
PURPOSE:To form a recess groove uniform in depth so as to improve a device in a static and a dynamic characteristic by a method wherein only an InGaAs layer is selectively removed through an etching, and then an AlGaAs layer is recess-etched. CONSTITUTION:An i-type. GaAs layer 2, an n-type AlGaAs layer 4, an n-type GaAs layer 5, an n-type InGaAs layer 13, a source metal electrode 9, and a drain electrode 10 are formed on a semi-insulating substrate. A resist 11 is applied onto the whole face and only a gate forming part 12 is removed through a photoengraving process. Only the InGaAs layer 13 is selectively removed using HCL or the like to expose a flat surface of the GaAs layer 5. Next, the GaAs layer 5 is etched with a mixed solution of H3PO4-H2O2-H2O to form a recess groove 14. A gate electrode 8 is formed in the groove 14 and the resist 11 is removed. The base of the recess groove 14 can be made flat, so that a field effect transistor (FET) which takes advantage of a two-dimensional electron gas (2DEG) layer is improved in a transfer conductance, increased in a cut-off frequency, decreased in noises, and improved in a high frequency property. |
