Monolithic microwave amplifiers formed by ion implantation into LEC gallium arsenide substrates

A fabrication procedure for broad-band monolithic power GaAs integrated circuits has been demonstrated which includes formation of via holes through the 100-µm-thick GaAs substrate. A selective implant of²⁹Si ions into the GaAs substrate is used to dope the FET channel region to 1.2 × 10¹⁷cm^-3. The ohmic contacts are AuGe/Ni/Pt and the gates are Ti/Pt/Au. A 1.5-µm-thick circuit pattern is achieved using metal rejection assited by chlorobenzene treatment of AZ1350J photoresist. Using undoped Czochralski wafers of GaAs pulled from a pyrolytic boron nitride crucible, integrated amplifiers have been produced which deliver 28 ± 0.7 dBm from 5.7 to 11 GHz. These chips are 2 mm × 4.75 mm × 0.1 mm thick.