ToF-SIMS Depth Profiling of Organic Films: A Comparison between Single-Beam and Dual-Beam Analysis

摘要

In dual-beam depth profiling, a high energy analysis beam and a lower energy etching beam are operated in series. Although the fluence of the analysis beam is usually kept well below the static SIMS limit, complete removal of the damage induced by the high energy analysis beam while maintaining a good depth resolution is difficult. In this study, a plasma polymerized tetraglyme film is used as the model organic system and the dimensionless parameter R, (analysis beam fluence)/(total ion fluence), is introduced to quantifythe degree of sample damage induced as a function of the analysis beam fluence. For a constant C_(60) etching beam fluence, increasing the analysis fluence (and consequently increasing the R parameter) increased the amount of damage accumulated in the sample. For Bi_n~+ (n = 1 and 3) and C_(60)~+ depth profiling, minimal damage accumulation was observed up to R = 0.03, with a best depth resolution of 8 nrri. In general, an increase in the Bi_n~+ analysis fluence above this value resulted in a decrease in the molecular signals of the steady state region of the depth profile and a degradation of the depth resolution at the polymer/substrate interface.