Performance of multicusp plasma ion source for focused ion beam applications

The multicusp plasma ion source has found many uses such as in ion implanters, ion projection lithography, and injectors for particle accelerators. This source is favorable for such applications because of its low ion temperature, small energy spread, and good stability. These properties also offer the tantalizing possibility of utilizing such a source to create a noncontaminating focused ion beam (FIB) system for semiconductor fabrication line use and advanced photomask repair applications. We have made measurements of the brightness of this ion source and have done some preliminary applications work with a Kr+-enabled FIB system for mask repair and ion milling. A specially designed multicusp plasma ion source has been used to measure focused beam spot size versus current relationships for several inert gas ion species. From these data the axial brightness of the ion source was ascertained. For the extraction of Kr+ from the source we find an angular intensity of 12 μA/sr and a virtual source size of 16....