Understanding dose correction for high-resolution 50 kV electron-beam lithography on thick resist layers
Mattias Åstrand, Thomas Frisk, Hanna Ohlin, Ulrich Vogt
Abstract
Electron-beam lithography (EBL) is a relevant technique to the nanoscience community as it enables the production of precise structures at the nanoscale. When writing features in a thick resist layer, dose insufficiency is typically encountered when resolution approaches the focal spot of the electron beam itself. We present a study of this phenomenon, a theory for its understanding and compensation, and a method for the assignment of the correct area dose for writing small features. Dose insufficiency originates from the proximity effect distributing energy in volumes of resist that are larger than intended. Based on a simple interpretation of the spread, a proximity effect correction (PEC) algorithm was established. Implementing this, we could realize high-quality nanostructures with direct-write 50 kV EBL on AR-P 6200 (CSAR 62) resist. The latter translates to quick and inexpensive exposures that offer good compatibility with further processes.