A long bar type silicon resonator with a high quality factor

This paper presents a long bar type silicon resonator with a high quality (Q) factor and an evaluation of the hermetic packaged device. This research aims at developing the integration technology of the capacitive silicon resonator on LSI for application of a timing device. The structure of the silicon resonator is defined by deep reactive ion etching of the top Si layer of a silicon on insulator wafer, and then the patterned top Si layer is transferred onto a low temperature co-fired ceramic substrate. Fabricated resonator is hermetically sealed by anodic bonding technique. The resonator is excited in the extensional bulk acoustic mode at a resonant frequency of 9.69 MHz. The Q factor measured for this device is approximately 368,000 at vacuum chamber pressure of 0.01 Pa. Additionally, the dependence of the Q factor on the operating pressure is measured in order to evaluate the vacuum level of the hermetically packaged device.