6533b861fe1ef96bd12c579a

RESEARCH PRODUCT

Aperture-edge scattering in MeV ion-beam lithography. II. Scattering from a rectangular aperture

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The capability of collimators to define beams of MeV ions with sub-100nm dimensions has recently been demonstrated. Such nanometer beams have potential applications in MeV ion-beam lithography, which is the only maskless technique capable of producing extremely high aspect-ratio micro- and nanostructrures, as well as in high resolution MeV ion-beam imaging. Ion scattering from the collimator edges can be a resolution-restricting factor in these applications. Scattering processes at edges are difficult to study using conventional simulation codes because of the complicated geometry. In this part of our work, the authors used the GEANT4 toolkit as a simulation tool for studying the behavior of beams of 3MeV He ions with 0.2–1mrad divergence impinging onto the programmable proximity aperture comprising four 100-μm-thick Ta plates. The transmission and scattering from the aperture are asymmetric due to the aperture design. For a perfectly parallel beam, the fluence of ions scattered from the aperture edges is...