We designed, fabricated and measured the performance of nanoelectromechanical (NEMS) switches. Initial data are reported with one of the switch designs having a measured switching time of 400 ns and an operating voltage of 5 V. The switches operated laterally with unmeasurable leakage current in the 'off' state. Surface micromachining techniques were used to fabricate the switches. All processing was CMOS compatible. A single metal layer, defined by a single mask step, was used as the mechanical switch layer. The details of the modeling, fabrication and testing of the NEMS switches are reported.
We present lifetime limitations and failure analysis of many packaged RF MEMS ohmic contacting switches with Au-Au, Au-Ir, and Au-Pt contact materials operating with 100 μN of contact force per contact in hermetically sealed glass wall packages. All metals were tested using the same switch design in a controlled environment to provide a comparison between the performance of the different materials and their corresponding failure mechanisms. The switch lifetimes of the different contact materials varied from several hundred cycles to 200 million cycles with different mechanisms causing failures for different contact materials. Switches with Au-Au contacts failed due to adhesion when thoroughly cleaned while switches with dissimilar metal contacts (Au-Ir and Au-Pt) operated without adhesion failures but failed due to carbon accumulation on the contacts even in a clean, packaged environment as a result of the catalytic behavior of the contact materials. Switch lifetimes correlated inversely with catalytic behavior of the contact metals. The data suggests the path to increase switch lifetime is to use favorable catalytic materials as contacts, design switches with higher contact forces to break through any residual contamination, and use cleaner, probably smaller, packages.
We present improvements in RF microelectromechanical switch design and fabrication that demonstrated improved lifetimes in cycled switches. First, implementation of RuO 2 -Au contact metallurgy into an existing design showed improved switch lifetime over switches with Pt-Au, Ir-Au, and Au-Au contacts. Second, the switch design was changed to reduce impact upon switch closure, and the fabrication process was changed to avoid the use of polymer sacrificial materials while including the RuO 2 -Au contact metallurgy. Switches with the new design were cycled to 10 billion cycles with a resistance less than 4 Ω, an insertion loss of 0.4 dB, and an isolation of 28.0 dB at 10 GHz. We propose that the catalytic behavior of the RuO 2 film prevents or delays the failure of the switches due to accumulation of carbon at the contacts. Additionally, the reduced impact upon closure prevented significant contact evolution during cycling.
Abstract-A switched Ku-band filter bank has been developed using two single-pole triple-throw (SP3T) microelectromechanical systems (MEMS) switching networks, and three fixed three-pole end-coupled bandpass filters. A tuning range of 17.7% from 14.9 to 17.8 GHz was achieved with a fractional bandwidth of 7.7 2.9%, and mid-band insertion loss ranging from 1.7 to 2.0 dB.
-A three-pole tunable end-coupled filter from 6 to 10 GHz was developed with a broad 35% tuning range. This tuning range was realized by switching distributed loading structures with radio frequency microelectromechanical systems (RF MEMS) capacitive switches. By tuning the coupling capacitors as well as the loading capacitors, the filter achieved a constant fractional bandwidth of 15±0.3 % and an insertion loss ranging from 3.3 dB to 3.8 dB over the entire band. Digital switching ensured good thermal stability, and microstrip transmission lines provided lower insertion loss than with coplanar waveguide. Future improvements are expected to decrease the insertion loss to below 2.1 dB.
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