Acceleration of e-beam lithography by minimized resist exposure for large scale nanofabrication

We investigated methods for accelerating the e-beam writing by minimizing the exposure time of the resist. We write on positive resist ZEP of 400 nm thick, keep a high voltage of 100 kV to maintain the high resolution of each dot, and a low dot map of 20k to reduce the number of the dots. We vary the current, dose and resist development time, to write 510, 210, 120 or 60 nm sized nanosquare or nanoslit arrays. The time durations for resist exposure and beam settling for each kind of patterns are calculated separately, and quality and deformation of each pattern are analyzed by scanning electron microscope images. The 510 to 120 nm sized patterns written by 0.8 nA with 178 mu C/cm(2) dose and 3 min development yield comparable quality to the ones written by 0.2 nA with 320 mu C/cm(2) and 30 s development, while the exposure time is reduced to 14%. Because e-beam writing time for one-dimensional nanoslits mainly spends on resist exposure, this acceleration is more prominent for nanoslits than two-dimensional nanosquares. (C) 2016 Published by Elsevier B.V.