LGS as a crystal for MEMS. Micromachining in HCl∶H2O. Anisotropy, database and simulations

This paper focuses on the complete characterization of the wet micromachining of 3D microstructures on LGS plates. Circular and square membranes and mesas are etched at 80°C in a HCl:H₂O solution of composition 2:1. The anisotropy of the wet etching is found to be of type 2 with ¿square¿ membranes bounded partly by curved facets and by curved contours at corners. The database of the continuum simulation tool TENSOSIM is progressively adjusted. Accordingly numerical 3D etching shapes derived with the proposed database are very close to experimental shapes. The objective of an accurate adjustment of the database of the simulator TENSOSIM in order to build an efficient tool for the CAD of LGS resonant structures is thus reached.