Determination of Elastic Modulus of Piezoelectric Aluminum Nitride Coating

Abstract

Aluminum Nitride (AlN) is a technologically important wide band gap semiconductor and a potential piezo-electric material for Biosensor application [1]. It is a clear candidate for the integration of surface acoustic wave (SAW) devices on chips with silicon-based electronics [2]. AlN may also prove to be useful for the integration of mechanical devices and also in the field of packaging of Bio-MEMS devices because of its superior thermal conductivity 130-140 (W/mK, room temp-100 deg C) and nontoxicity. In the current work an attempt has been made to determine the elastic modulus of AlN coated on Si-microcantilevers, employing the concept of symmetrically laminated beam theory for the first time at the micro level thus avoiding the coupling effects. So far the earlier studies have been done only using simple beam theory. Modal vibration frequencies for microcantilevers without and with the AlN coating were used, along with analytical models and knowledge of the Si modulus, to “back out” the modulus of AlN [3].