E-Beam direct write alignment strategies for the next generation node

摘要

New types of alignment marks to be applied in electron beam direct write (EBDW) have been studied theoretically andexperimentally. The dependence of signal contrast and signal form on such mark properties like step height, mark pitch and stackmaterial has been investigated in detail using Monte Carlo simulations. The different alignment marks were etched in Si to different depths and the respective alignment repeatability was de-termined with a Vistec SB3050 DW lithography tool. Finally, for the most promising mark, test exposures were per-formed and the overlay determined.