Single-Chip Multiple-Frequency ALN MEMS Filters Based on Contour-Mode Piezoelectric Resonators

Abstract

This paper reports experimental results on a new class of single-chip multiple-frequency (up to 236 MHz) filters that are based on low motional resistance contour-mode aluminum nitride piezoelectric micromechanical resonators. Rectangular plates and rings are made out of an aluminum nitride layer sandwiched between a bottom platinum electrode and a top aluminum electrode. For the first time, these devices have been electrically cascaded to yield high performance, low insertion loss (as low as 4 dB at 93MHz), and large rejection (27 dB at 236 MHz) micromechanical bandpass filters. This novel technology could revolutionize wireless communication systems by allowing cofabrication of multiple frequency filters on the same chip, potentially reducing form factors and manufacturing costs. In addition, these filters require terminations (1 kOmega termination is used at 236 MHz) that can be realized with on-chip inductors and capacitors, enabling their direct interface with standard 50-Omega systems. This material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of the University of Pennsylvania's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to pubs-permissions@ieee.org. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.

Experimental Investigation of a Cavity-Mode Resonator Using a Micromachined Two-Dimensional Silicon Phononic Crystal in a Square Lattice

“…However, the motional impedance is also very high due to weak capacitive electroacoustic coupling. On the other hand, although the motional impedance of piezoelectric-based microresonators can be below 50 Ω, the Q factor cannot be very high due to high loss in the piezoelectric materials [3].…”

Piezoelectric nanoelectromechanical resonators based on aluminum nitride thin films

“…1 Some of the most ubiquitous among these are electrical oscillators, clocks, and microbalances based on piezoelectric crystals such as quartz. 2,3 Recent development of micromachining techniques has greatly facilitated the realization of various miniaturized piezoelectric devices, including zinc-oxide ͑ZnO͒ beam-structured, 4 disk, 5 and film bulk acoustic resonators ͑FBARs͒, 6 the noteworthy Agilent's commercialized AlN FBARs, 7 AlN contour-mode resonators and filters, 8 and monolithically integrated FBAR-complementary metal oxide semiconductor ͑CMOS͒ filters. 9 All these piezoelectric microelectromechanical systems ͑MEMS͒ have relied on active layers of approximately micron scale thickness that provide strong electromechanical coupling.…”

“…Among its attributes are intrinsic integrability, high efficiency and electrical tunability, low power consumption, and low thermal budgets for materials processing permitting post-CMOS integration. [5][6][7][8][9] Previously we have prototyped piezoelectric NEMS using epitaxial gallium arsenide ͑GaAs͒ heterostructures. 14 To date, however, nanoscale resonators have not yet been realized with materials having higher piezoelectric coupling efficiency.…”

Characterization of forced localization of disordered weakly coupled micromechanical resonators

“…Microelectromechanical systems (MEMS) resonators have been widely used in various applications such as communications [1][2][3] , medical diagnostics 4,5 , and inertial navigation [6][7][8] . Typically, the structural parameters of the resonant element change with the addition of ambient physical/chemical quantities 9 .…”