| A new fabrication methodology that allows self-alignment of a micromechanical structure to its anchor(s) has been developed to achieve vibrating radial contour mode polysilicon micromechanical disk resonators with resonance frequencies up to 1.156 GHz and measured Q's at this frequency 2,650 in both vacuum and air. For these resonators, self-alignment of the stem to exactly the center of the disk it supports allows balancing of the resonator far superior to that achieved by previous versions, allowing the present devices to retain high Q while achieving frequencies in the gigahertz range for the first time. Furthermore, via design strategies that merge different materials at critical locations, this work has demonstrated micromechanical resonators in chemical vapor deposited (CVD) nanocrystalline diamond with record frequencies up to 1.89 GHz and with order of magnitude increases in Q at this frequencies to values >10,000, At 498 MHz, Q's up to 55,300 in vacuum and 35,550 in air have been demonstrated, both of which sets frequency-Q product record at 2.75 x 10 13 in vacuum, and 1.77 x 1013 in air, both of which now exceeds the 1 x 1013 of some of the best quartz crystals.;In addition, closed-form analytical models for the Q-limiting anchor losses have been developed and verified by the experimental data, providing valuable guidance on geometrical and material-centric design of radial contour mode disk resonators.;Finally, a mixing-based measurement setup and an electrically accessible substrate ground plane have been employed to characterize micromechanical resonators in the ultra-high frequency (UHF) range, both of which prove instrumental in suppressing feedthrough noises to allow clean measurement of gigahertz vibrating resonator frequency characteristics. |
