| 摘要 |
PURPOSE:To keep the distance between ohmic electrodes and a gate electrode constant even if there is deviation of plating guantity due to the fluctuation of the plating condition by determining that distance automatically by the guantity of overetching of an Al film. CONSTITUTION:An N type GaAs performance layer 12, an SiO2 film 21 and an Al film 31 are successively formed on a GaAs substrate 11 and parts of the Al film 31 where ohmic electrodes are not formed are covered by photoresistor films 41. Then the film 31 and the film 21 are removed successively using the films 41 as masks. And the parts of the film 31 remained under the films 41 is overetched to the length equal to the distance between the ohmic electrodes and a gate electrode. Then a metal layer for the ohmic electrodes are formed and the photorresistor films 41 are dissolved and unnecessary parts of the metal layer are removed by lifting-off a source electrode 511 and a drain electrode 512 are formed by thermal treatment. Then the surface is covered by photoresistor excpt the parts where wirings are formed. After the parts of the Al film and the SiO2 film where wiring are formed are removed. An Al film is formed and unnecessary parts of the Al film is removed by lifting-off and the wirings 611 and 612 are formed. |
