In order to apply to S-Band (1-4.5 GHz) of wireless communication system, we designed and fabricated a high-insolating RF-MEMS switch by surface micromachining technology in this study. In terms of the micro switch, we performed the structural design, high frequency simulation, components process integration and high-frequency measurement in this study. Especially for making components be high-isolation, low-loss and low-driving voltage, we proposed the following three methods: (i) adjusting the space and width of the transmission lines to improve the RF performance; (ii) applying the stress imbalance, by using dual metal composite top electrode, to form a arched contact electrode and reduce the drive voltage efficiently; (iii) using non-isometric spring structure to stabilize the electrode movement of the components. Besides, we did the optimizing simulation for this study, which were supported by Ansoft-HFSS and ADS, in terms of the micro switch which has different structural design as mentioned above. The size of the optimized RF micro-switch which we developed for this study is only 145 £gm ¡Ñ 205 £gm. Switched from on-state to off-state, the component needs 36.5V drive voltage only. According to the result of the commercial network analyzer in 1-4.5GHz frequency range, the isolation rate of the components reaches -59.721dB while off-state; the insert los reaches -1.625dB while on-state.

This thesis aimed to develop a novel micro thermal electric generator (£g-TEG) with a series-array bridge microstructure utilizing microelectromechanical systems (MEMS) technology. By integrating the tens of thousands of micro-thermocouple in a centimeter square area, the temperature difference between the hot plane and cold plane of the presented £g-TEG can be converted into a useful electrical power. The thermoelectrically transferred output electrical power is suitable for recharging various mobile communication products. There are two main configurations of the conventional £g-TEGs have been proposed, including the vertical and lateral structure types. The heat flow of the vertical-type £g-TEG can be directly transferred by the thermocouples and hence the energy loss through the substrate can be efficiently reduced and the thermoelectrical conversion efficiency is usually higher than vertical-type £g-TEG. However, to obtain a useful electrical power output, the height of the vertical-type £g-TEG usually more than 100 micrometers and this will increase the production difficulty and fabrication cost. In contrast, the height of the lateral-type £g-TEG is only about several micrometers and hence the production difficulty and fabrication cost are lower than vertical-type £g-TEG. The non-neglect energy loss through the substrate of lateral-type £g-TEG will constrain the efficiency of electrical power generation. Using the surface micromachining technology, tens of thousands of suspending micro polysilicon thermocouple are integrated and serially connected to increase the efficiency of electrical power generation and reduce the substrate energy loss. The main fabrication processes adopted in this research are including seven thin-film deposition processes and five photolithography processes. The implemented Poly-Si based £g-TEG demonstrates a maximum temperature difference of 1.29¢J between the hot plane and cold plane (under nine different substrate temperatures), a maximum output voltage of 4.47 V/cm2 and a maximum output power of 601.4 nW/cm2. The comparison and analysis of experimental and simulation (ANSYS) results under the nine different substrate temperatures are investigated and the influence of length of suspending micro thermocouples is also discussed in this work.