| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 94 === This thesis includes design and fabrication of IC-compatible RF MEMS switch by MEMS technology. Compared to other actuation mechanisms, electrostatic RF MEMS switches have small footprint, extremely low power consumption, high switching speed, and ease of integration with CMOS circuits. However, high actuation voltage of electrostatic driven switches remains an essential issue for commercial applications. To solve this problem, the novel design of low actuation voltage push-pull MEMS switch using residual stress of bi-metallic microstructure is reported in this thesis. Low voltage driving mechanism is realized by taking advantage of residual stress of two bi-metallic parallel arch-like beams, which are mechanically connected with an insulating lever beam. Utilizing the nature of residual stress, a small gap between DC driving pair-electrodes and a large separation between signal line and switching structure can be achieved, resulting in low actuation voltage and high isolation. The primary limitation of this switch is to control the residual stress of microstructure. A non-contact 3D measurement is performed through a WYKO interferometer to evaluate the beam deformation subject to pre-designated residual stresses. It is found that the gap between the apex of each arches and the underneath insulating layer is range from 1.38μm to 3.4μm. The non-uniform stress distribution makes it difficult to fabricate the same apex height of parallel arch-like beams. The stiction problem is observed while releasing the microstructure, which really affects the functionality of the switches. Finally, the suggestions are proposed in the end of this thesis for eliminating these problems.
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