Langasite resonant structure: Micromachining and characterisation

This paper focuses on the micromachining of 3D microstructures on LGS plates by anisotropic wet etching. Several etching conditions are investigated to determine the best experimental way to fabricate 3D microstructures. The study covers the composition, the concentration and the temperature of the etching bath. Several types of experimental results are used to determine the conditions that provide consistent and reproducible results: the anisotropic factor, the etch rate and the degree of surface quality, the undercutting, the solution chemical aggressiveness toward masks. Etching profiles, SEM images are discussed on several orientations of etched plates. According to the experimental data base, an etchant is selected and the experimental conditions of etching are determined. 3D resonant structures are fabricated on the X cut using photolithographic process before the etching step. The final shapes of the structures are then characterized in view of inertial sensor design.