Depth profiling of polymer samples using Ga+ and C-60(+) ion beams

摘要

In this contribution, we focus on the use of C-60(+) ions for depth profiling of model synthetic polymers: polystyrene (PS) and poly(methylmethacrylate) (PMMA). These polymers were spin coated on silicon wafers, and the obtained samples were depth-profiled both with Ga+ ions and C-60(+) ions. We observed an important yield enhancement for both polymers when C-60(+) ions are used. More specifically, we discuss here the decrease in damage obtained with C-60, which is found to be very sensitive to the nature of the polymer. During the C-60(+) sputtering of the PMMA layer, after an initial decrease, a steady state is observed in the secondary ion yield of characteristic fragments. In contrast, for PS, an exponential decrease is directly observed, leading to an initial disappearance cross section close to the value observed for Ga+. Though there is a significant loss of characteristic PS signal when sputtering with C-60(+) ions beams, there are still significant enhancements in sputter yields when employing C-60(+) as compared to Ga+. Copyright (C) 2008 John Wiley & Sons, Ltd.