Novel alignment system for imprint lithography

A novel alignment system for imprint lithography in the deep sub-hundred na nometer realm is proposed. The new system is inherently more precise than t he alignment systems used in conventional projection lithography because al ignment marks on an imprint mold (the functional equivalent of a photomask in projection lithography) are directly compared to alignment marks on a wa fer with no intermediate optics or reference points. If the measured misali gnment is so severe that all marks cannot be brought into registration simu ltaneously by the usual x-y translations and rotations, the mold is deliber ately deformed with a system of piezoelectric actuators in such a way that its induced distortions precisely match those on the wafer and all of the a lignment marks at each chip site can be pulled into registration simultaneo usly. Finite-element analysis indicates that using actuators to distort the mold is superior to distorting the wafer. (C) 2000 American Vacuum Society . [S0734-211X(oo)05406-8].