The Multiple E-beam Direct Write (MEBDW) technology has been considered a promising solution for the next
generation lithography to delineate 32-nm half-pitch and beyond. A low-energy, say 5 keV, e-beam direct writing system
has advantages in lower exposure dosage, less heating effect on resist, and less damage to devices underneath, comparing
with a high energy one, such as 50 keV or 100 keV. However, the low-energy electron-beam is easily blurred due to
forward scattering in the substrate due to its shallow penetration and hence loses resolution. In this paper, variables
affecting patterning fidelity of a raster-scan MEBDW system are investigated.
In order to realize a MEBDW system with acceptable throughput, a relatively large beam size is chosen for sufficient
beam current to sustain throughput while maintaining enough resolution. The imaging resolution loss and the proximity
effect, due to beam blurring through the resist, have been observed. The in-house software MOSES, incorporating the
Monte Carlo simulation and the Double Gaussian model was used to evaluate 1-D and 2-D pattern fidelity with various
exposure conditions. The line width roughness, which represents 1-D fidelity, was evaluated on 32-nm dense lines.
Pattern fidelity of 2-D features such as the zigzag poly line and dense metal patterns was also examined. The impact to
LWR of using the edge dithering method, instead of dosage modulation, to control the line width accuracy beyond the
pixel size was studied.