Reconfigurable Piezoelectric MEMS Resonator Using Phase Change Material Programmable Vias

This paper reports on the demonstration of a reconfigurable aluminum nitride (AlN) piezoelectric microelectromechanical systems (MEMS) resonator using phase change material (PCM) programmable vias. Two 10-μm × 10-μm Ge₅₀Te₅₀ PCM programmable vias are monolithically integrated with a piezoelectric MEMS resonator, and used to dynamically reconfigure the terminal connections of its top and bottom electrodes, which determine the distribution of the electric field across the piezoelectric layer and therefore the equivalent electrical impedance of the resonator. The ability to reconfigure the device to operate in four different states is experimentally demonstrated: 1) lateral field excitation mode (both vias OFF); 2) resonator static capacitance, C₀ ≈ 484 fF; 3) motional resistance, R_m ≈ 320 Ω; 4) thickness field excitation mode-high impedance (via 1 ON, C₀ ≈ 564 fF; R_m ≈ 470 Q); 5) thickness field excitation mode-low impedance (via 2 ON, C₀ ≈1459 fF; R_m ≈155 Q); and 6) SHORT (both vias ON, the resonator is reconfigured into a short circuit). This paper sets a milestone toward the demonstration of an innovative technology platform, based on the monolithic integration of AlN resonators and PCM switches, capable of delivering highly reconfigurable radio frequency components, enabling new radio architectures with enhanced spectrum coverage.