Capability of ion beam projection optics for microfabrication

Applicability of ion beam projection optics for sputtering fabrication is i nvestigated by using third-order aberration theory. Under the Kohler illumi nation condition that minimizes off-axial aberration, the total beam curren t of the shaped beam formed in large-reduction-ratio projection column is l arger than that of a conventional focused ion beam. In a preliminary experi ment with 50:1-reduction projection optics, the edge blur of the shaped bea m is estimated to be less than 0.1 mu m for a total beam current larger tha n 30 nA. Ion beam projection optics is thought to be suitable for applicati ons that require high-throughput processing.