Performance Enhancement and Restoration of Micromechanical Resonators Via UV-Ozone Treatment

An ultraviolet (UV)-ozone treatment process capable of atomic-scale surface cleaning has enabled the highest measured room temperature Q and frequency-Q product (f-Q) for on-chip polysilicon acoustic resonators to date while also demonstrating an ability to restore catastrophically contaminated devices to operational performance specs. Specifically, UV-ozone cleaning improved the Q of a heavily contaminated 61-MHz polysilicon wineglass disk resonator by over 282 from a very-low 921 to a record-setting-high of 259,910. Post-release UV-ozone treatment further raises the Q of a 303.2-MHz polysilicon wineglass disk resonator by 30.5% to 89,172, yielding the highest measured f-Q to date of 2.700
¹³
for polysilicon micromechanical resonators. Initial experiments seem to confirm that the high surface-to-volume ratio of micro and nano-scale structures amplifies susceptibility to surface-derived loss mechanisms. UV-ozone treatment also raised the Q of a 311.2-MHz AlN resonator from 789 to 2,574, providing evidence of a material agnostic benefit.