A COMPARATIVE MATERIALS STUDY OF MAGNETRON ION ETCHED GAAS USING FREON-12, SICL4 AND BCL3

Etch characteristics and residual damage incurred via magnetron ion et ching of GaAs using three different etch gases, namely, freon-12, SiCl 4 and BCl3, at two different power levels has been studied. Transmissi on electron microscopy, scanning electron microscopy, Auger electron s pectroscopy, and Schottky diode measurements were employed to determin e the suitability of the processed surfaces for device fabrication. La ttice damage was incurred in all processing situations in the form of small dislocation loops. Samples etched in freon-12 at the highest pow er density exhibited the roughest surface morphology, while those etch ed in SiCl4 and BCl3 resulted in planar surfaces. The Schottky barrier diode characteristics, for all etch gases, degraded with increasing p ower density. The electrical quality of the BCl3-etched GaAs at the lo west power density was superior to that of the other etch gases at all power levels. The etched profiles Of SiCl4 and BCl3 yielded vertical sidewalls, whereas freon-12 yielded a negative undercut. The BCl3-etch ed GaAs surfaces were residue-free, while those of freon-12 and SiCl4 exhibited surface or sidewall contamination. Our results have demonstr ated that magnetron ion etching with BCl3 yields planar residue-free s urfaces with minimum material surface damage and superior electrical i ntegrity compared with GaAs etched with freon-12 or SiCl4.