Magnet assisted stage for vibration and heat reduction in wafer scanning

Wafer scanning stages must deliver high accelerations/decelerations at motion reversals to achieve high productivity. The resulting inertial forces cause vibration of the machine frame and overheating of the linear motor actuators, thus diminishing the accuracy and increasing the cost of the stages. The novel stage design presented in this paper uses magnetic repulsion to provide assistive forces to the linear motors during acceleration/deceleration to reduce actuation force requirements and overheating. Vibration is reduced by transmitting the assistive forces to the ground, not the machine frame. 66% and 55% reduction in vibration and heat, respectively, are demonstrated using a prototype stage.