ALN SILICON LAMB-WAVE MICROSENSORS FOR PRESSURE AND GRAVIMETRIC MEASUREMENTS/

We have studied a pressure and a gravimetric sensor using an AIN film over a silicon membrane. The membrane is micromachined using both anis otropic and isotropic chemical etching. The AIN thin film is deposited by the sputtering method. Elastic waves are generated and detected th rough interdigital transducers (IDTs) calculated at the frequency of 9 0 MHz for the S-o Lamb-wave mode. The behaviour of such a sensor is pr esented. We have analysed and experimentally tested the pressure and h ave calculated the gravimetric sensitivity. By using the opposite temp erature behaviours of silicon and AlN, a satisfactory temperature comp ensation is achieved. Results obtained from such experiments show sens itivities that agree with theoretical sensitivities provided by a theo retical model which includes the effect of the mass loading of the dep osited thin-layer material.