RF-MEMS switches with new beam geometries: improvement of yield and lowering of actuation voltage

One main obstacle that reduces the yield in RF MEMS technology is the variation of the residual stress resulting from fabrication. Residual stress can occur across the wafer, from the wafer to another wafer, or from one batch of fabrication to another one, and is more pronounced in cantilever bean type switches. For the present paper we have used new sets of dimples to reduce the sensitivity of the structure to the stress level. The SEM pictures of the proposed configuration and those of the conventional beam switch fabricated on the same wafer are analyzed sufficiently. The comparison amply proves soundness of our method. The high actuation voltage is another main issue that requires considerable investigation, and is generally higher in clamped-clamped beam type switches. In order to reduce the actuation voltage, we have designed, fabricated and tested several configurations with different supporting beams. The actuation voltage of as low as 10 volts is achieved and all switches exhibit excellent RF performance. At 40GHz the insertion loss of the switches varies ranging from 0.35dB to 0.70dB. It is evident that at a lower frequency ranges this becomes even better. At 40GHz, the return loss for all switches measured -24dB. Lastly, isolation is better than 20dB to 30dB for all the frequency band of interest.