We report on a novel microfabrication method to
fabricate aluminum nitride (AlN) piezoelectric
microstructures down to 2 microns size by a surface
micromachining process. Highly c-axis oriented AlN thin
films are deposited between thin Cr electrodes on
polysilicon structural layers by rf reactive sputtering. The top Cr layer is used both as a mask to etch the AlN thin films and as an electrode to actuate the AlN piezoelectric layer. The AlN layer is patterned anisotropically by wet etching using a TMAH (25%) solution. This multilayer stack uses silicon-di-oxide as a sacrificial layer to make free-standing structures. One-port scattering paramenter measurement using a network analyzer show a resonant frequency of 1.781 GHz on a clamped-clamped beam suspended structure. The effective electromechanical coupling factor is calculated as 2.4 % and the measured bandwidth is 13.5 MHz for one such a doubly clamped beam (990x30) μm2.
|Conference||2005 Symposium on Design, Test, Integration and Packaging of MEMS/MOEMS, DTIP 2005|
|Period||1/06/05 → 3/06/05|