Quartz microresonator sensors for monitoring thin film thickness

This paper describes a quartz microresonator sensor for monitoring thin film thickness. A microresonator of tuning fork-type with stepped vibration bars vibrating in torsion which can be approximately regarded as "clamped-free bar" is very available for monitoring thin film thickness because it has excellent frequency temperature behavior over a wide temperature range of room temperature to high one of about 200/spl deg/C. In this paper, a relationship of resonant frequency to thin film thickness of Ak and Al is theoretically and experimentally clarified for the microresonator, so that the frequency deviation is proportional to the film thickness deposited on the top of the tuning arms, and the calculated values are in good agreement with the measured ones. This microresonator is, therefore, very available for monitoring thin film thickness.