Plasma Etching of Lithium Niobate on Insulator (LNOI) Wafers
Résumé
Patterning lithium niobate (LN) is a hot topic of research due to the attractive properties of LN: non-linearity, piezoelectricity, high electro-optic or elasto-optic coefficients, for integrated optics. The reactive ion etching (RIE) technique is positioned as a reference low-loss mass-manufacturing technique, especially for waveguides. Compared to FIB (Focused Ion Beam), this technique allows the fabrication of larger structures and offers the possibility to realize cone or pillar structures. However, the protecting RIE masks tend to transfer its roughness to the edges of the waveguide, which is the principal source of propagation losses. At FEMTO-ST, we have investigated two types of roughness-optimized masking solutions aiming to be easy to use without any polishing post-processing step.