Performance of multicusp plasma ion source for focused ion beam applications

The multicusp plasma ion source has found many uses such as in ion implante rs, ion projection lithography, and injectors for particle accelerators. Th is source is favorable for such applications because of its low ion tempera ture, small energy spread, and good stability. These properties also offer the tantalizing possibility of utilizing such a source to create a nonconta minating focused ion beam (FIB) system for semiconductor fabrication line u se and advanced photomask repair applications. We have made measurements of the brightness of this ion source and have done some Preliminary applicati ons work with a Kr+-enabled FIB system for mask repair and/on milling. A sp ecially designed multicusp plasma ion source has been used to measure focus ed beam spot size versus current relationships for several inert gas ion sp ecies. From these data the axial brightness of the ion source was ascertain ed. For the extraction of Kr+ from the source we find an angular intensity of 12 muA/sr and a virtual source size of 16.9 mum, giving an approximate v alue for the image-side brightness (at 30 keV) of 1650 A/cm(2)sr. We find g ood sputtering rates for the Kr+ beam, and the Aerial image measurement sys tem measurements show essentially 100% transmission of 193 nm light through photomask quartz that had been implanted with a significant dose of krypto n. (C) 2000 American Vacuum Society. [S0734-211X(00)07106-7].