P4L-4 Etch Rate Dependence on Crystal Orientation for Lithium Niobate

This paper presents experimental data for the etch rate of lithium niobate (LiNbO₃) as a function of crystal orientation. The etching characterization is a fundamental technology needed for the fabrication of new sensors, actuators or other new devices. In this study, 30 mm spheres of LiNbO₃ were etched in hydrofluoric acid and in a solution of hydrofluoric and nitric acids, to determine the etch rate dependence on crystal orientation. It was found that the maximum etch rate was on the -Z face and the etching showed a three-fold symmetry about the Z axis. The Wulff-Jaccodine method as well as the data collected from the etched spheres were used to predict the etched shape of a wafer. The predicted shape agreed with that found during etching.