Thermally excited micromechanical vacuum resonator

A micromechanical resonator is proposed and realized, which is made in silicon-unitized structure. It consists of a single-crystal silicon beam and two P-type silicon resistors. One mister is used to excite the beam vibrating and the other to sense vibration of the beam. The dimension of the resonator is about 4 x 2.5 mm(2), the resonant frequency is about 7.8 KHz, Q factor about 190 in air and above 2500 in vacuum degree of 7.5 x 10(-4) Pa. The theory of thermal excitation is analyzed and the characteristics of the resonator are tested. We conclude that the resonator can be applied to vacuum measurement by the means of closed-loop resonating circuit, The design and realization of the circuit are described.