Optimizing focused ion beam created solid immersion lenses in bulk silicon using design of experiments

In search of efficient solutions improving image resolution for backside failure analysis, the creation of solid immersion lenses in bulk silicon using focused ion beam has been investigated deeply in parametric detail. This technique is optimized using design of experiments, providing a better understanding of the pure ion beam sputtering process. It produces SILs in less than 20 min of processing time and offers an additional magnification of 3.2×. The optimal setup of this FIB created SIL is demonstrated and provides an improvement in resolution by a factor of 1.8. Limits of this technique are encountered and analyzed for future development.