Patterning Piezoelectric LiTaO3 Using Reactive Ion Beam Etching for High Performance Thin Film SAW Device Applications
(Room Exhibit Hall A)
30 Apr 19
2:30 PM
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4:00 PM
Lithium tantalate (LiTaO3) is used in many applications including nonlinear optics, infrared sensors, pyroelectric detectors and surface acoustic wave (SAW) devices. Thin film SAW devices using LiTaO3 exhibit high performance in RF filter applications. Patterning of LT thin films using traditional inductively coupled plasma or reactive ion etching (ICP/RIE) based methods exhibits low etch rate and often results in rough surface and redeposition on the sidewall. On the other hand, ion beam etching is used to achieve a very smooth surface, high etch rate and without redeposition. Here we report the patterning of LT thin films using ion beam etching (IBE) and reactive ion beam etching (RIBE). Etch rate and selectivity of LT to photoresist at various reactive gas percentage were evaluated. Then optimization of etching angle was performed to achieve high etch rate and selectivity without any sidewall redeposition. LT etch rate of up to 80 nm/min and high selectivity to photoresist of 1.3:1 with a very smooth etched surface of ~2 nm average roughness was obtained with further optimization of beam voltage, beam current and tilt angle. This research has huge implications in fabricating LiTaO3 thin film SAW RF filters for next-generation mobile and wireless applications.