Background, Motivation and Objective Piezoelectric resonators usually exhibit a large coupling coefficient which leads a small motional resistance, but unfortunately they show a medium Q. Various loss mechanisms existing in piezoelectric resonators have been investigated recently where the interfacial loss, causing from the stress jump at the interface and the anchor loss, representing the acoustic energy leakage via the support tethers, are considered as the primary loss mechanisms. The metal-to-piezoelectric stress can be minimized with the optimized deposition conditions. The anchor loss can be reduced by different approaches, such as positioning the tethers at nodal locations in the vibration mode or using different materials for the support and vibrating body to form acoustic impedance mismatch.