Etching characteristics of LiNbO3 in reactive ion etching and inductively coupled plasma

Abstract

The etching characteristics of congruent LiNbO3 single crystals including doped LiNbO3 and proton-changed LiNbO3 have been studied in reactive ion etching (RIE) and inductively coupled plasma (ICP) etching tools, using different recipes of gas mixtures. The effects of parameters including working pressure, RIE power, and ICP power are investigated and analyzed by measurement of etching depth, selectivity, uniformity, etched surface state, and sidewall profile by means of focused ion beam etching, energy-dispersive x-ray analysis, secondary ion mass spectroscopy, scanning electron microscopy, and surface profilometry. The effects of a sample carrier wafer coating have also been investigated. Optimized processes with high etching rates, good mask selectivity, and a near-vertical profile have been achieved. Ridge waveguides on proton-exchanged LiNbO3 have been fabricated and optically measured.

Role of Single-Crystal Pillars in Forming the Effective Properties and Figures of Merit of Novel 1–3 Piezocomposites

“…The substrate was selectively removed using reactive ion etching (RIE) and inductive coupled plasma (ICP) etching tools with a hybrid of SF 6 /Ar gases. ICP etching of the LiNbO 3 has reached ∼200 nm/min at 1000 W ICP with selectivity to Ni being ∼10 [11]. The final nano-pillars of LiNbO 3 achieved by this NIL approach can be seen in Fig 1. Typical nano-pillar heights achieved were 500 nm to 1 µm with a pitch equivalent to the imprint master (600 nm).…”

Towards a SAW based phononic crystal sensor platform

“…It is far less developed for piezoelectric materials and typically based on reactive ion etching (RIE) [e.g. [6][7][8][9]. LiNbO 3 is the more appropriate material from the electroacoustic point of view; however, it is more challenging than quartz.…”

Highly selective electroplated nickel mask for lithium niobate dry etching

“…RIE is in itself a highly controllable and versatile dry process involving both physical and chemical effects to achieve directive and anisotropic material removal. It has already been demonstrated that lithium niobate can be dry etched using fluorine-based chemistries, [14][15][16][17] and ICP-RIE has previously been used on X-or Z-axis crystallographic orientations of lithium niobate to successfully fabricate ridge waveguides or photonic crystals, usually after proton exchange [18][19][20] but there is no report of any specific process allowing to dry etch structures that are several microns in depth in lithium niobate. The fabrication of very deep or very high aspect ratio structures is actually seriously impaired by the formation of lithium fluoride ͑LiF͒ compounds during the etching process that are relatively nonvolatile, leading to redeposition phenomena impeding the material removal.…”