Paper AS-TuM6
The Effect of Cluster Ion Analysis Fluence on Interface Quality in SIMS Molecular Depth Profiling

Tuesday, October 21, 2008, 9:40 am, Room 207

Recent advances in cluster secondary ion mass spectrometry (SIMS) have led to the ability to perform molecular depth profiling for a range of organic materials. Cluster ion beams such as Au₃, Bi_n, SF₅, and C₆₀ have shown varying abilities to probe through organic films and soft substrates. The work has been successful because of the premise of sufficiently high target sputter yields that remove beam-induced molecular damage as it is created. Hence, molecular signals can be maintained without significant damage cross sections at ion beam fluences well beyond the traditional “static limit” employed with atomic ion beam analysis. However, in certain modalities, it has been postulated and in some cases demonstrated that a “dual beam analysis” can be exploited for maximum sputtering yield and minimum damage of the erosion beam, while acquiring imaging data with a better-focused smaller cluster beam such as Bi_n. This study finds that the effects of the analysis fluence shall not be considered negligible to the imparting of permanent beam-induced damage within the organic materials being depth profiled. Instead, it is found that increasing the analysis fluence can degrade the quality of the interface widths of a high-quality PMMA film on silicon, despite the prospects of the sputter beam to remove accumulated beam-induced damage. The data will be discussed in terms of implications for cluster SIMS molecular depth profiling.