Sample-tracking Vibration Isolation with Hybrid Reluctance Actuators for Inline Metrology

摘要

This paper proposes a sample-tracking vibration isolator based on hybrid reluctance actuators to bring a vibration sensitive instrument toward inline metrology. The hybrid reluctance actuators vertically move the platform to mount the instrument and maintain its position with respect to the target sample, rejecting floor vibrations. For compensating crosstalk motions due to manufacturing and assembly tolerances, the actuator forces are balanced, demonstrating a reduction by a factor of about 10 for frequencies below 70 Hz. In order to regulate the moving platform motion, a feedback controller is designed achieving a closed-loop bandwidth of 260 Hz. Experiments reveal that the proposed vibration isolator reduces the vibrations (RMS value) from 37.5nm to 1.6 nm and consequently realizes nanometer positioning resolution in a vibrational environment. These experiments successfully demonstrate the effectiveness of the proposed vibration isolator and the capability of the hybrid reluctance actuators to handle floor vibrations.