Surface morphology and removal rates for dry- and wet-etched novel resonator materials Part I. La3Ga5.5Ta0.5O14

La3Ga5.5Ta0.5O14 shows promise for high temperature, high frequency crystal resonator applications. We report on two methods for thinning wafers of th is material. Using wet chemical etching, we found that HCl- or HF-based sol utions produced etching at room temperature, while HNO3 and H3PO4 produced practical rates at greater than or equal to 70 degrees C. In all of these s olutions, the etching was reaction-limited with activation energies > 14 kc al . mol(-1). Some degree of surface smoothing was achieved with HCl etchin g at elevated temperatures. The near-surface stoichiometry was unaffected b y the wet etch treatments. Using dry etching, we found that Cl-2-based disc harges produced rates < 950 Angstrom . min(-1) under all conditions, with C l-2/Ar maintaining the best surface morphology. (C) 2000 Elsevier Science B .V. All rights reserved.