MAGNETRON ION ETCHING OF THROUGH-WAFER VIA HOLES FOR GAAS MONOLITHIC MICROWAVE INTEGRATED-CIRCUITS USING SICL4

A dry etching process is described for the fabrication of through-wafe r via holes in GaAs-based monolithic microwave integrated circuits by magnetron ion etching using SiCl4. The process has been used to etch v ia holes through 80 mu m GaAs substrates with good anisotropy and etch rates exceeding 1 mu m/min for via holes as small as 18x20 mu m(2). E tch anisotropy appears to be due to an etch-inhibiting layer, which fo rms on the sidewalls but can be removed readily using a brief SF6/O-2 etch. The process also exhibits good selectivity to Au and Ni frontsid e metal. (C) 1998 American Vacuum Society.