Detecting response of square and circular Si/AlN/Al membranes transducers by Laser Vibrometry Doppler and Impedancemeter

This paper investigates the vibration analysis of square and circular piezoelectric micro-transducers in the hundred kHz range as a function of experimental tools. These micro-transducers have been actuated by a piezoelectric Aluminum Nitride (AlN) 0.9 μm-thin layer sandwiched between N-doped Silicon (Si) 20μm-thick layer and aluminum (Al) 0.4μm-thin layer. Si/AlN/Al square and circular membranes, with size fixed to 1.5 mm were fabricated using micromachining technology. Analytical and 3D finite element method (3D-FEM) analysis using Comsol software has been performed to model static, modal and vibration behavior of these membranes. Typical numerical simulations and experimental results are presented and discussed. Comparison with standard impedancemeter measurement is shown to assess the performance of Laser Doppler Vibrometry (LDV) system. This work´s main contribution is mechanical and electrical characterization and comparison with a model.