Single Crystal Bulk Acoustic Resonator for 5 GHz and High-Power Applications

A new processing technology is presented in this paper to fabricate single crystal bulk acoustic resonator (SC-BAW) with the piezoelectric film of ∼0.5 µm thickness, aimed at 5 GHz Applications. Theoretical analysis and simulation were carried out to design the SC-BAW structures with Z-cut LiNbO3 as the piezoelectric layer. Two kinds of SC-BAWs were fabricated and tested, including back-cavity and Bragg reflector type SC-BAWs. Results showed SC-BAWs have resonant frequency around 5 GHz and the quality factor above 1800. The back-cavity SC-BAW has better performance than reflector type SC-BAW. Two electrode structures were proposed to reduce the ripples and improve the power capacity of SC-BAWs.