High Aspect Ratio Microstructures in LiNbO3 Produced by Ion Beam Enhanced Etching

Abstract

AbstractThis work presents data on damage evolution, volume expansion and etching behavior of LiNbO3 irradiated with Ar+-ions as a function of irradiation and etching conditions. Single crystals of x- and z-cut LiNbO3 were irradiated at room temperature and 15 K using Ar-ions with energies between 60 and 600 keV and ion fluences between 5 × 1012 and 1 × 1015 cm-2. The damage formation investigated with RBS channeling analysis depends on the crystal cut as well as on the irradiation temperature. Irradiation of z-cut material at 300 K causes complete amorphization at 0.4 dpa (displacements per target atom). In contrast 0.27 dpa are sufficient to amorphize the x-cut LiNbO3. Irradiation at 15 K reduces the number of displacements per atom necessary for amorphization to 0.18 dpa. To study the etching behavior ∼500 nm thick amorphous layers were generated via multiple irradiations with Ar+-ions. Etching was performed in HF-solution of different concentration and at different temperatures. The influence of the irradiation and etching conditions on damage formation and etching of LiNbO3 is discussed. In conclusion, negligible etching of the perfect crystal, high etching rates and high contrast of Ion Beam Enhanced Etching (IBEE) allow the realization of high aspect ratio microstructures in LiNbO3.