  With a two-dimensional (2D) optical mask, nanoscale patterns are created for
the first time in an atom lithography process using metastable helium atoms.
The internal energy of the atoms is used to locally damage a hydrofobic resist
layer, which is removed in a wet etching process. Experiments have been
performed with several polarizations for the optical mask, resulting in
different intensity patterns, and corresponding nanoscale structures. The
results for a linear polarized light field show an array of holes with a
diameter of 260 nm, in agreement with a computed pattern. With a circularly
polarized light field a line pattern is observed with a spacing of 766 nm.
Simulations taking into account many possible experimental imperfections can
not explain this pattern.
