Due to low power operation, intrinsic integrability and compatibility with CMOS processing, aluminum nitride (AlN) piezoelectric (PZE) microcantilevers are a very attractive paradigm for resonant gas sensing. In this paper, we theoretically investigate their ultimate limit of detection and enunciate design rules for performance optimization. The reduction of the AlN layer thickness is found to be critical. We further report the successful development and implementation in cantilever structures with a 50 nm thick active PZE AlN layer. Material characterizations demonstrate that the PZE e(31) coefficient can remain as high as 0.8Cm(-2). Electrically transduced frequency responses of the fabricated devices are in good agreement with analytical predictions. Finally, we demonstrate the excellent frequency stability with a 10(-8) minimum Allan deviation. This exceptionally low noise operation allows us to expect a limit of detection as low as 53 zg mu m(-2) and demonstrate the strong potential of AlN PZE microcantilevers for high resolution gas detection.

In this paper, we demonstrate the high sensing performances of a DMMP vapor sensor system based on 50 nm thick AlN film microcantilevers. These devices are particularly interesting for low power integrated gas sensors systems. One key factor for their gas sensing performances optimization relies on the reduction of the AlN layer thickness. Thanks to a digital PLL setup we demonstrate high frequency stability with an Allan deviation of 5.10-8. Finally, using DKAP polymer for surface functionalization of the cantilever, we measure DMMP vapor concentration down to 25 ppb and predict from frequency noise an ultimate resolution of 10 ppb at the level of the state of the art of DMMP sensing.

We present the fabrication and characterization of a 90μm × 40μm × 885nm piezoelectric micro-cantilever resonator containing a 50nm thick Aluminum Nitride (AlN) piezoelectric film for transduction. Material characterizations demonstrate that our AlN deposition technique enables the fabrication of ultra-thin films with high piezoelectric coefficient e31 = 0.78C.m-2. Fully electrical actuation and detection of the cantilever resonance behavior is evidenced using onchip electric bridge and instrumented probe trans-impedance amplifier. Finally, based on Allan deviation measurement results, we demonstrate the potential of this cantilever for gas detection with an expected limit of detection equal to 70zg.μm-2.