DRY AND WET ETCHING OF SCALMGO4

ScAlMgO4 is a potential substrate for GaN epitaxy. We have compared th ree different plasma chemistries for dry patterning of ScAlMgO4, namel y Cl-2-, F-2- or CH4/H-2-based. Significant etch rates (> 1000 Angstro m min(-1)) were obtained only with Cl-2 (and BCl3), and the rates were directly proportional to both ion energy and ion density in the plasm a. Since the etching is ion-assisted under all conditions, extremely a nisotropic sidewalls are produced on patterned features. Of the wet ch emistries investigated at 300 K, only HF wet chemical solutions were f ound to etch ScAlMgO4, though HNO3 can be used at greater than or equa l to 150 degrees C for removal of substrate polishing damage. (C) 1998 Published by Elsevier Science Ltd.