Effects of thermal annealing condition on N-incorporated ZnO films in FBAR devices

A new approach to fabricate the film bulk acoustic wave resonator (FBAR) devices is presented that employs high-quality piezoelectric ZnO films, particularly sputter-deposited in a mixture of N₂O and Ar gases as the reactive and sputtering gases, respectively. Various thermal annealing treatments were performed on the deposited ZnO films and their effects on the resonance characteristics of the FBAR devices were investigated. With a process optimisation, the FBAR devices could be fabricated to have excellent resonance characteristics in terms of return loss.