Artifacts in multilayer depth profiling: Origin and quantification of a double peak layer profile of Ag in ToF-SIMS depth profiles of an Ag/Ni multilayer

Highlights: • MRI model quantifies Ag double peak in Ag/Ni multilayer SIMS depth profile. • Double layer structure of Ag intensity explained by oxygen induced matrix effect. • The roughness parameter depends linearly on the sputtered depth. • The atomic mixing length depends on the actual composition. • A misleading method of usual profile normalization is identified. Depth profiles of a Ni/Ag multilayer with 25 nm nominal layer thickness obtained by Time-of-Flight Secondary Mass Spectrometry (ToF-SIMS) show the usual rounded top shape of the Ni layers, but a strange profile of Ag with two peaks of different intensities. Application of the Mixing-Roughness-Information depth (MRI)-model for quantification of both depth profiles revealed the fact that the only way to explain the measured Ag profile was the assumption of interfacial oxygen that promotes a strong matrix effect on the Ag ion intensity. Furthermore, it was demonstrated that the often applied normalizing of the elemental ions by the sum of the two ion intensities removes the double peak structure but results in a wrong quantification.