MANUFACTURE OF SEMICONDUCTOR DEVICE

摘要

PURPOSE:To form an enhancement mode FET (EFET) and a depletion mode FET (DFET) on an identical substrate by forming an epitaxial film for determing the respective threshold voltages for the EFET and the DFET. CONSTITUTION:Undoped GaAs 2 and Si-doped n-type AlGaAs 3 are formed epitaxially in succession on a semi-insulating GaAs substrate 1 by an MOCVD method; SiO2 is deposited by a CVD method; an SiO2 mask 4 is formed by photolithography and wet etching; Si-doped n<+> type GaAs 5 is grown epitaxially by a low-pressure MOCVD method; after photoresist has been coated, this layer is patterned and etched; a metal for an ohmic electrode is coated by a vacuum deposition method; it is lifted off to form an ohmic electrode 8. Photoresist is coated again; after patterning, SiO2 is etched partially; a metal for a gate electrode is coated by the vacuum deposition method; gate electrodes 10 and 11 are formed by a lift-off method.