Abstract
Nanoelectromechanical (NEM) relays show promise in a wide variety of low power applications. NEM relays have near-zero leakage current, in contrast to the relatively high leakage current of nanoscale CMOS transistors, thus enabling hybrid CMOS-NEM relay systems that are more energy efficient. If NEM relays can be fabricated in the back-end-of-line (BEOL) metallization process, they can be added to a CMOS integrated circuit without adding significantly to the die area. In this paper, we demonstrate a CMOS BEOL-compatible fabrication process of NEM relays with protected, buried interconnects. The NEM relay processing steps are at temperatures below 425 °C and all mechanical and chemical processing steps are designed to avoid damage to underlying CMOS transistors. We demonstrate a lateral relay with buried interconnect that switches for more than 1000 cycles with resistances below 300 kΩ in nitrogen at atmospheric pressure.
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Acknowledgments
This work was funded by the DARPA Nano Electromechanical Switches Program, Drs. Amit Lal and Tayo Akinwande, program managers. The lead author thanks the National Science Foundation and the Ford Foundation for graduate student fellowships. Fabrication costs for W. A. Clary were partially supported by a grant from the School of Engineering at Stanford. Fabrication costs for K. L. Harrison were partially supported by a grant from the University’s Office of Student Affairs through the Engineering Diversity Program. Device fabrication was done at the Stanford Nanofabrication Facility (SNF) and the Marvell Nanofabrication Laboratory, University of California, Berkeley. SNF is a node of the NSF National Nanotechnology Infrastructure Network (NNIN). Scanning electron microscope imaging and x-ray photoelectron spectroscopy analysis were performed in the Stanford Nano Shared Facilities (SNSF). We would like to also thank Nicholas Bousse, Kevin Wang, Dr. Kamran Shavezipur and Dr. Scott Lee for their help, and Profs. Subhasish Mitra and H.-S. Philip Wong for their guidance and support.
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Harrison, K.L., Clary, W.A., Provine, J. et al. Back-end-of-line compatible Poly-SiGe lateral nanoelectromechanical relays with multi-level interconnect. Microsyst Technol 23, 2125–2130 (2017). https://doi.org/10.1007/s00542-016-2932-1
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DOI: https://doi.org/10.1007/s00542-016-2932-1