Paper AS-TuM2
Expanding the Application of C₆₀ in TOF-SIMS Depth Profile Analysis

Tuesday, October 21, 2008, 8:20 am, Room 207

It is acknowledged that atomic ion beams (e.g. Ar⁺, Cs⁺ and O₂⁺) introduce chemical damage to organic materials during depth profile experiments, and the mechanism by which chemical damage occurs is well understood. In the past several years, many publications have demonstrated that buckminsterfullerene (C₆₀) ions can be used to successfully depth profile organic materials with minimal accumulation of damage or modification of the chemical composition within the ion beam-exposed region of the material. In addition, depth profiles of molecular ion signals have become much more routine with the use of C₆₀⁺ ion beams. However, it has been noted in some publications that the sputter rate does not remain uniform through an organic matrix and that efficient sputtering ceases at various depths; such effects are material dependent. The use of higher voltage C₆₀⁺ beams has extended the range of molecular depth profiling, but changes in sputter rate still occur. These limitations seem to be related, in part or in whole, to either cross-linking of the matrix or accumulation of carbon which reduces the C₆₀⁺ ion-induced sputter rate. A recent paper by J.-J. Shyue and coworkers has shown that C₆₀⁺/Ar⁺ co-sputtering can be used to extend the depth profile range and maintain a more constant sputter rate.¹ In this paper, we apply the C₆₀⁺/Ar⁺ co-sputtering methodology for TOF-SIMS depth profiling of organic matrices to investigate the effect of co-sputtering on sputter rate, profile range and secondary ion yield.

¹ Y.-Y. Chen, et al., Anal. Chem. 80 (2008) 501.