Design and fabrication of a novel two-dimension MEMS-based tunable capacitor

In this paper, a novel bulk micromachined two-dimension tunable capacitor is proposed with the techniques of silicon-glass wafer bonding and deep reactive ion etch. The micromechanical tunable capacitor comprises a suspended plate array, a bottom electrode array corresponding with it that is fixed on the glass substrate, and side-interdigitated comb structures. When the suspended plate array is laterally driven by the electrostatic comb actuator, the capacitance (the first dimension) between the suspended plate array and bottom array, together with the interdigitated comb capacitance (the second dimension) tune linearly with applied voltage. Thus it increases tuning ratio and unbiased base capacitance. The finite element method simulation with ANSYS 5.5 is used to analyze the varying behavior of the capacitor. Meanwhile, the fabrication process is very simple in that only three masks are used, and very efficient to achieve high-Q values, because it employs glass instead of silicon as substrate.