A sensor for thin film thickness monitor using torsional quartz crystal resonators of stepped, free-free bar-type

This paper describes a quartz microsensor for monitoring thin film thickness. A microresonator of free-free bar-type with stepped vibration bar vibrating in torsion as well as that of tuning fork-type is available for monitoring thin film thickness because it has excellent frequency temperature behavior over a wide temperature range of room temperature to a high of about 200/spl deg/C. In this paper, a relationship of resonant frequency to thin film thickness of Au 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 arm, and the calculated values show good agreement with the measured ones.