32GHz resonant-fin transistors in 14nm FinFET technology

摘要

Monolithic integration of microelectromechanical resonators in IC technology has been explored extensively over the past few decades in the effort to achieve on-chip clocks, RF filters, and physical, chemical, and biological sensors. Various approaches for resonator integration, actuation, and sensing have been proposed and demonstrated, targeting high Q and high frequency performance [1]. These include the “MEMS-last” approach with low temperature materials deposited on complete CMOS chips [2,3], and “MEMS-in-the-middle” in which resonators are defined with post-processing of the front end and back end materials of the IC stack [4]. These methods require additional processing and packaging steps that make frequency scaling challenging and may limit resonator Q. Meanwhile, in the case of monolithically integrated MEMS resonators, transistor sensing can be used to enhance transduction efficiency and reduce parasitics, which can prohibit 2-port detection for high frequency resonance [5]. In this work, we introduce the Resonant Fin Transistor (RFT) fabricated in GLOBALFOUNDRIES 14nm FinFET technology, leveraging the vertical 3D geometry of FinFETs (Fig. 21.3.1) to efficiently confine, drive, and sense acoustic vibrations in the solid (unreleased) CMOS stack with no post-processing or custom packaging. We demonstrate 32GHz resonators with Q~49,000.