Low-Cost Production Of Broadband MEMS Switches Moves Closer To Realty

Nov. 25, 2002
A surface-micromachined, all-metal wafer-bonding process has been used with high-resistivity silicon to develop an electrostatically actuated broadband microswitch with impressive performance characteristics for dc to RF applications. Device yields of...

A surface-micromachined, all-metal wafer-bonding process has been used with high-resistivity silicon to develop an electrostatically actuated broadband microswitch with impressive performance characteristics for dc to RF applications. Device yields of 90% achieved at a commercial MEMS foundry make this process a potential low-cost method for manufacturing broadband MEMS switches for applications like cell phones and operation, the beam is deflected by applying about 80 V between the gate and source electrodes, which produces a contact force of 200 µN (Fig. 1). The contact material is a thin layer of platinum deposited on the underside of the beam and the drain. Wafer-level capping ensures a hermetic seal (Fig. 2).

Typically, each switch has eight contacts in parallel to yield total on-resistance of less than about 0.2 ‡ at dc and low frequencies. On-response time was measured at 5 µs. Lifetimes of more than 1010 cycles (using currents of 10 mA or less) have been achieved. The switch can handle up to 1 A and has a low insertion loss of just 0.3 dB at 2 GHz and 30 dB of isolation.

Prototypes are being made for the U.S. Air Force for an X-band, electronically steerable antenna array. Process and design modifications are also under way to optimize RF performance and contact resistance. A four-terminal device for better isolation is being investigated as well.

Contact Rick Morrison at (978) 562-3866, ext. 296, or [email protected].

About the Author

Roger Allan

Roger Allan is an electronics journalism veteran, and served as Electronic Design's Executive Editor for 15 of those years. He has covered just about every technology beat from semiconductors, components, packaging and power devices, to communications, test and measurement, automotive electronics, robotics, medical electronics, military electronics, robotics, and industrial electronics. His specialties include MEMS and nanoelectronics technologies. He is a contributor to the McGraw Hill Annual Encyclopedia of Science and Technology. He is also a Life Senior Member of the IEEE and holds a BSEE from New York University's School of Engineering and Science. Roger has worked for major electronics magazines besides Electronic Design, including the IEEE Spectrum, Electronics, EDN, Electronic Products, and the British New Scientist. He also has working experience in the electronics industry as a design engineer in filters, power supplies and control systems.

After his retirement from Electronic Design Magazine, He has been extensively contributing articles for Penton’s Electronic Design, Power Electronics Technology, Energy Efficiency and Technology (EE&T) and Microwaves RF Magazine, covering all of the aforementioned electronics segments as well as energy efficiency, harvesting and related technologies. He has also contributed articles to other electronics technology magazines worldwide.

He is a “jack of all trades and a master in leading-edge technologies” like MEMS, nanolectronics, autonomous vehicles, artificial intelligence, military electronics, biometrics, implantable medical devices, and energy harvesting and related technologies.

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