Characterizing Inductively-Coupled-Plasma Etching of Single Crystalline Lithium Tantalate for Micro-Acoustic Applications

In this paper, the etch characteristic of different crystalline planes (X-cut and 42 ˚ Y-cut) of lithium tantalate (LT) is studied by performing inductively coupled plasma reactive ion etching (ICP-RIE) with different CF
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/Ar gas mixtures and varying RIE powers using sputtered or e-beam evaporated Ni masks. Consequently, the influence of the etch parameters on the etch rate, selectivity, and roughness of the etched patterns was investigated. The best results in terms of sidewall roughness and selectivity are achieved at 28/30 SCCM of Ar/ CF
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with RIE power of 80 W for sputtered Ni mask. These results will be used as a guideline for fabrication of micro-acoustic resonators on LT substrates.