REACTIVE ION ETCHING OF VIA HOLES FOR GAAS HIGH-ELECTRON-MOBILITY TRANSISTORS AND MONOLITHIC MICROWAVE INTEGRATED-CIRCUITS USING CL2 BCL3/AR GAS-MIXTURES/

A process for through-the-wafer via hole connections to each individua l source contact for monolithic microwave and millimeter wave integrat ed circuits and power high electron mobility transistors has been deve loped using reactive ion etching in Cl2/BCl3/Ar gas mixtures. Placing vias in this manner eliminates the need for source airbridges, which m inimizes source inductance and results in increased gain and efficienc y. The GaAs etch rate and resultant etch profiles have been studied as functions of bias voltage, gas mixture, flow rate, via mask dimension , and etch time.