Development of ion sources for ion projection lithography

Abstract

Multicusp ion sources are capable of generating ion beams with low axial energy spread as required by the ion projection lithography (IPL). Longitudinal ion energy spread has been studied in two different types of plasma discharge: the filament discharge ion source characterized by its low axial energy spread, and the rf-driven ion source characterized by its long source lifetime. For He+ ions, longitudinal ion energy spreads of 1–2 eV were measured for a filament discharge multicusp ion source which is within the IPL source requirements. Ion beams with larger axial energy spread (∼7 eV) were observed in the rf-driven source. A double-chamber ion source has been designed which combines the advantages of low axial energy spread of the filament discharge ion source with the long lifetime of the rf-driven source. The energy spread of the double chamber source is approximately 2 eV.