  Electron-beam (e-beam) lithography is widely employed in fabrication of 2-D
patterns and 3-D structures. A certain type or shape of the sidewall in the
remaining resist profile may be desired in an application, e.g., an undercut
for lift-off and a vertical sidewall for etching, or required for a device.
Also, as the feature size is decreased well below a micron, a small variation
of the sidewall slope can lead to a significant (relative) CD error in certain
layers of resist. Therefore, it is important to understand effects of spatial
dose distribution on sidewall shape and be able to achieve the desired shape.
In this study, via simulation, the relationship among the total dose, spatial
distribution of dose, developing time and sidewall shape, and performance of
the method developed to optimize the dose distribution for a target sidewall
shape have been analyzed. The simulation results have been verified through
experiments.
