Air-Based Contactless Wafer Precision Positioning System

This paper presents the development of a contactless sensing system and dynamic evaluation an air-bearing-based precision wafer positioning system. The stage is response to trend seen in high-tech industry, where substrates are becoming thinner larger reduce cost increase yield. Using handling it possible avoid damage contamination. works by floating substrate on thin film air. A viscous traction force created steering airflow. cascaded control design structure has been implemented system, inner loop controller (ILC) controls actuator which steers airflow outer (OLC) position controlling reference ILC. dynamics ILC evaluated optimized for performance substrate. vibration disturbances also handled bandwidth improved 300 Hz. For OLC, linear charge-coupled device as sensor. analysed. During steady-state, this resulted error 12.9 μm RMS, little more than two times resolution. OLC approaching 10