Chemical analysis of nickel silicides with high spatial resolution by combined EDS, EELS and ELNES

The purpose of this study is to develop methodologies for the characterization of Ni-silicides by analytical TEM techniques. The measurements are performed in STEM mode to allow a good spatial resolution. Initial examination of the Ni-silicide phases is done by energy-dispersive X-ray spectroscopy (EDS). It is shown that quantification results with high accuracy and precision are obtained when a Ni-silicide reference layer is used as a standard, and an absorption correction is applied to the data. The EDS quantification results are then used as a reference for the quantitative electron energy-loss spectroscopy (EELS) analysis. It is shown that EELS analysis yields quantification results with high accuracy and precision, when the EELS data are treated with a model based approach. The EELS analysis is combined with a study of the Ni-L2,3 near-edge structure (ELNES). The ELNES of the phases can be distinguished either visually or by calculating the branching ratio from the spectra with the model based approach. This paper shows that the different Ni-silicide phases can be distinguished with these EELS based methods. The accuracy and precision of the EDS and EELS results are compared.