Tuning the quality factor of bulk micromachined structures using the squeeze film damping

This study aims to demonstrate the possibility of tuning quality factor of a micromachined structure using the air damping of small squeeze film area (300 /spl mu/m/sup 2/ to 800 /spl mu/m/sup 2/). Two micromachining process has successfully been established to fabricate novel stationary structures using thin films and bulk silicon. Thus, the stationary structure and a vibrating micromachined cantilever will form the squeeze film region. According to the measurement, the quality factor of the vibrating beam remarkably dropped 65% when the squeeze film area increased from 0 /spl mu/m/sup 2/ to 800 /spl mu/m/sup 2/ under a 760 torr ambient pressure. Even when the ambient pressure was merely 20 mtorr, the quality factor of the beam still dropped 20% for the same case. The damping due to the squeeze film effect cannot be ignored even for a very small area. Consequently, the proposed stationary structures can be exploited to significantly alter the quality factor of dynamic systems.