FABRICATION AND ANALYSIS OF THIN FILM LITHUM NIOBATE RESONATORS FOR 5GHz FREQUENCY AND LARGE k(t)(2) APPLICATIONS

This work presents the fabrication and analysis of suspended thin film Lithium Niobate resonators. The yield of the new fabrication process presented below is >90% showing devices with high k(t)(2) of 28% resonators at 5GHz, making them suitable for high frequency and large bandwidth 5G filter applications. The device consists of a suspended thin film Lithium Niobate (LN) with interdigitated aluminum electrodes. These Interdigitated Transducers (IDTs) excite standing shear YZ acoustic Al mode in a Z-cut LiNbO3 resonator. Dependence of frequency, electromechanical coupling (k(t)(2)) and spurious modes is demonstrated on design parameters by simulations and measurements. These parameters arc used to study frequency tunability and eliminate spurious modes of resonators for 50 filter applications. Currently demonstrated devices is also suitable to be scaled for mass production by using deep UV lithography instead of e-beam.