Lithium niobate surface structuration for phononic crystal fabrication

Abstract

Reactive Ion Etching (RIE) has been used to etch micron-sized holes which are several microns in depth in lithium niobate, mostly on Y-and V-rotated cut substrates, the underlying idea being the realization of phononic crystal devices. The etching process is based on the use of sulfur hexafluoride as the etching gas. Photoresist and sputtered or electroplated metals masks were used and compared to ensure high process selectivity and good sidewall verticality. Maximum mask selectivity was found to be of the order of 20. Etched depths larger than 10 J-tm and aspect ratios above 1.5 have been achieved. Sidewall verticality higher than 73°is also reported. The technique has been applied to the fabrication of phononic SAW devices designed to operate at a frequency around 200 MHz. The phononic structure consists of periodical arrays of 9 /--lm diameter, with a 10 J-tm period etched in V-cut lithium niobate.

Alignment nature of ZnO nanowires grown on polished and nanoscale etched lithium niobate surface through self-seeding thermal evaporation method

“…Nanoscale surface etching of lithium niobate has been previously reported using chemical etching [34,35] and reactive ion etching (RIE) techniques [36]. In order to get an estimate of the minimum etch depth required for the growth of well-aligned ZnO nanowires on the lithium niobate substrate, reactive ion etching of the substrate was performed using PLASMALAB100 ICP380 (Oxford Instruments) RIE Equipment.…”