Fabrication of Low-Residual-Stress AlN Thin Films and Their Application to Microgenerators for Vibration Energy Harvesting

For obtaining low residual stress, AlN thin films were prepared on Si substrates with diverse bottom electrode materials of Pt/Ti, Au/Cr, Al, and Ti by the electron cyclotron resonance (ECR) deposition technology. Among them, AlN thin films deposited on the substrate with the Al bottom electrode demonstrated not only low residual stress but also high enoughc-axis orientation, and thus they were utilized to fabricate microgenerators by the micromachining process for converting environmental vibration energy into electric energy. The AlN microgenerator had a resonant frequency of 1042.6 Hz and the output power was 1.42 µW at the vibration frequency and 1gacceleration.