Development of FBAR devices based on thermal annealing treatments of nitrogen [N]-incorporated ZnO films

The improvements of the resonance characteristics of the film bulk acoustic wave resonator (FBAR) devices fabricated employing nitrogen [N]-incorporated ZnO films are presented. The N-incorporated ZnO films were sputter-deposited in a mixture of N₂O and Ar gases as the reactive and sputtering gases, respectively. Mainly due to the thermal annealing treatments of the N-incorporated ZnO films, the resonance characteristics could be significantly improved. The excellent return loss (S₁₁) of -63 dB was observed at ~0.6 GHz, which is better than ever reported in this device technology regime.