Study On RF MEMS Switch Devices

RF MEMS technology becomes more and more attractive in the communicationfield nowadays. Switch is one of the most important element in RF circuit, study onRF MEMS switch with low insertion-loss, high isolation, low actuation voltage hasbecome hot topics. RF MEMS switch can be used as an independent component, or aswitch array to achieve better performance or different functions according to itsapplications. Since RF MEMS switch is in general connected and supported bycoplanar-waveguide (CPW), so the optimization of CPW is the first step of RFMEMS switch device design.Four kinds of RF MEMS devices are designed in this thesis, including low lossCPW, capacitive shunt switch with capacitive connection, Ohmic serial switch anddistributed phase shifter. The corresponding process flows and layout is designed, andseveral key processes are investigated in detail. Based on the developed processes,the designed devices are realized and measured.The thesis firstly introduces the design method of CPW;a convenient CPWparameter table is obtained by calculation. An optimized design of capacitiveshunt switch is carried out, which has lower actuation voltage and resonant frequency.An ohmic switch with compatible process is designed. A process to realize metallicdimple with seed layer is established. A distributed phase shifter is designed.Three process flowes are designed for those devices. A set of layout that iscompatible with three process flows is presented. Key process steps are investigated,including seed layer etching, gold electroplating and polyimide patterning.The designed device are obtained and measured. The insertion-loss ofCPW is less than 0.85dB. The actuation voltage of designed capacitive switchis 20V, its insertion-loss is 1.03dB@20GHz, and its isolation is26.5dB@20GHz. The actuation voltage of distributed phase shifter is 65V.In order to trim the effect of pad structure in microwave performancemeasurement, a method to extract the "pure" device data is developed.