AlN piezoelectric films for sensing and actuation

Aluminum Nitride (AlN) is explored as a thin film material for piezoelectric MEMS applications. A pulse DC reactive sputtering technique is used to deposit the AlN thin films and process parameters are optimized to obtain good crystallinity and high c-axis orientation films. A CMOS compatible process is developed and employed to fabricate surface acoustic wave devices based on AlN/Si structure targeting operation in liquid environment and shearmode resonators for mass sensing applications. We also investigate sputtered Ti thin films as electrodes for thin and flexible AlN piezoelectric devices.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc

Influence of seed layer on crystallinity and orientation of pulsed — DC sputtered AlN thin-films for piezoelectric actuators

Aluminum Nitride thin films with the desired properties for piezoelectric actuators are grown by pulsed DC sputtering on Si (100) substrates coated with different seed layers (Al/1%Si, Mo, Ti). The influence of sputtering parameters and the seed layers on crystallinity and orientation of the AlN films is investigated. Raman spectroscopy measurements are performed and the results are analyzed to identify the optimal deposition conditions. The high-cc axis orientation of AlN thin films obtained with Ti as a seed layer was confirmed by X-ray diffraction. It appears that seed layers of 200 nm Ti are a valid alternative to Molybdenum or Platinum for IC compatible piezoelectric actuators fabrication.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc

Fabrication of AlN slender piezoelectric cantilevers for highspeed MEMS actuations

Very thin piezoelectric cantilevers based on AlN layers using titanium Ti thin film electrodes are fabricated and characterized. By optimizing the Ti sputtering parameters, a very low stress (156 MPa) layers stack with high crystallinity and strong (002) orientation of the AlN films is obtained. Finally, a simple fabrication process, fully CMOS compatible, is developed to realize slender (900 nm) piezoelectric microcantilevers. A resonant frequency of 19.3 kHz is measured for 200 ?m long cantilevers. The deflection of cantilever is 6 nm/V and 189 nm/V for quasistatics and resonant frequency actuation, respectively. This makes the fabricated cantilevers attractive for high-speed MEMS actuators.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc