Piezo Actuated Active Damping in a Semiconductor Lithographic Scanner

摘要

Decreasing line width imposes increasing demands on the accuracy of the ASML Twinscan platform. Vibrations of the lens play a dominant role in the accuracy of the projection in a lithographic scanner. In order to decrease these vibrations, a damper based on the 'smart disc' principle is placed between lens and metrology frame. Vibrations are reduced with this damper by a factor of 10 (dependant on the direction) and the projection accuracy is increased accordingly.