Mechanically reliable MEMS variable capacitor using single crystalline silicon (SCS) structure

In this paper, we firstly proposed a mechanically reliable parallel-plate type variable capacitor with a single crystalline silicon (SCS) supporting structure. The demonstrated variable capacitor was fabricated using an SiOG (silicon-on-glass) process, and both mechanical and electrical characteristics were measured. Total chip size was 1.05 mm×0.72 mm, and the pull-in voltage was measured to be 37 V. With and without the applied DC bias, the measured S₁₁ and S₂₁ were changed from -15.6 dB to -5.1 dB, and from -0.49 dB to -2.3 dB at 30 GHz, respectively. The measured capacitance at the up and the down state was 30 fF and 140 fF, respectively. Therefore, the capacitance ratio is calculated to be 4.67.