The Design of Aluminum Nitride-Based Lead-Free Piezoelectric MEMS Accelerometer System

In this study, we successfully deposited c-axis-oriented aluminum nitride piezoelectric films via low-temperature dc sputtering method. Based on the X-ray diffraction (XRD) and TEM analyses, deposited films with a c-axis monocrystal were identified. The effective d _33,f value of the aluminum nitride (AlN) films is 5.92 pC/N, which is better than most of the reported data using dc sputtering processing. Using ANSYS software, we simulated and designed MEMS accelerometers based on AlN films. Furthermore, we successfully fabricated MEMS accelerometers. The sensitivity of the MEMS accelerometer is 1.49 mV/g, and the resonance frequency is 7.2 kHz. The MEMS accelerometer was combined with a sensing circuit constituting a module. The sensitivity of the module increases approximately tenfold. Finally, the vibration of spindles was successfully detected using the designed module.