Capacitive RF-MEMS Switch Design And Research Of Failure

With the development of RF-MEMS switch, people usually pay more attentionto its characteristics and reliability. In this paper, fixed-cantilever switch structure isdesigned by Intellisuite and structure parameters are analyzed. At the same time, themain switch theory and fabrication procedures are introduced briefly. In the latter ofthis paper, the reliability is researched through three perspectives which areimpacting velocity, built-in electric field and dielectric charging respectively.Dielectric charging lifetime prediction formula is given in the end. The main researchcontent is as follows.The switch parameters are optimized by Intellisuite and experiment results showthat beam length, beam width, thickness, plate distance and transmission line widthare200μm,30μm,0.6μm,2μm,150μm respectively, which can make driven voltageless than16V.The turn-on time prediction model of fixed-cantilever switch is built andstructural parameters are further optimized. Experiment results show that beamlength and transmission line width make big influence on turn-on time. In this paper,beam length equals to200μm and CPW width equals to150μm which can makeswitch turn-on time less than8μs.Switch impacting model and dielectric built-in electric field model have beenbuilt by utilizing MATLAB which analyzes bias voltage effect. Experiment resultshows that high frequency pulse voltage can increase switch lifetime in sometime.Switch lifetime prediction model is built by analyzing charges distribution ondielectric surface. And experiment results show that when elastic coefficient in therange of4-16N/m, dielectric thickness in the range of0.4-1μm, radio frequencypower less than4w, Si3N4as dielectric material, switch lifetime can exceed1000hours.