2014 年 80 巻 810 号 p. DR0029
An absolute displacement sensor has been proposed for anti-vibration. Until now, it has been shown that the absolute displacement sensor is effective as a feedback sensor. Then, we would like to apply the same sensor to semiconductor exposure apparatuses, however detection bandwidth is limited due to resonances called high frequency dynamics. Since the proposed sensor is constructed by servo-type velocity sensor and original feedback circuits, the sensor has the same characteristics in high frequency dynamics. We have found that the pendulum of the velocity sensor have vibration modes on each resonance frequency by experimental modal analysis. In shaking test, same resonances appeared. Then, we conducted to suppress the resonances by loading viscoelastic materials, metal pieces, and TMD (Tuned Mass Damper). As a result, the resonances can be most suppressed by loading TMD. Moreover, we tried loading TMD in consideration of vibration modes, loading point, and constitution of TMD. The resonances were drastically suppressed by loading TMD on multiple points. In addition, we confirmed effects of high frequency dynamics and its suppression under the feedback of the absolute displacement sensor's velocity signal. As result, the resonances can be suppressed by loading TMD under the feedback. In this paper, suppression methods of high frequency dynamics are described and the absolute displacement sensor is applied to FB control.
