A generalized foundry-oriented CMOS-MEMS platform well suited for integrated micromechanical resonators alongside IC amplifiers has been developed for commercial multi-user purpose and demonstrated with a fast turnaround time of only 3 months and a variety of design flexibilities for resonator applications. With this platform, different configurations of capacitively-transduced resonators monolithically integrated with their amplifier circuits, spanning frequencies from 500 kHz to 14.5 MHz, have been realized with resonator Q's ranging between 700 and 3500. This platform, specifically featured with various configurations of structural materials, multi-dimensional displacements, different arrangements of mechanical boundary conditions, tiny supports of resonators, large transduction areas, well-defined anchors and performance enhancement scaling with IC fabrication technology, offers a variety of flexible design options targeted for sensor, timing reference, and RF applications. In addition, resonators consisting of metal-oxide composite structures fabricated by this platform offer an effective temperature compensation scheme for the first time in CMOS-MEMS resonators, showing TCf six times better than that of resonators merely made by CMOS metals.
Abstract-Vibrating polysilicon micromechanical ring resonators, using a unique extensional wine-glass-mode shape to achieve lower impedance than previous UHF resonators, have been demonstrated at frequencies as high as 1.2 GHz with a Q of 3,700, and 1.52 GHz with a Q of 2,800. The 1.2-GHz resonator exhibits a measured motional resistance of 1 MΩ with a dc-bias voltage of 20 V, which is 2.2 times lower than the resistance measured on radial contourmode disk counterparts at the same frequency. The use of larger rings offers a path toward even lower impedance, provided the spurious modes that become more troublesome as ring size increases can be properly suppressed using methods described herein. With spurious modes suppressed, the high-Q and low-impedance advantages, together with the multiple frequency on-chip integration advantages afforded by capacitively transduced mechanical resonators, make this device an attractive candidate for use in the front-end RF filtering and frequency generation functions needed by wireless communication devices.
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