Determination of thickness and composition of high-k dielectrics using high-energy electrons

We demonstrate the application of high-energy elastic electron backscattering to the analysis of thin (2-20 nm) HfO₂ overlayers on oxidized Si substrates. The film composition and thickness are determined directly from elastic scattering peaks characteristic of each element. The stoichiometry of the films is determined with an accuracy of 5%-10%. The experimental results are corroborated by medium energy ions scattering and Rutherford backscattering spectrometry measurements, and clearly demonstrate the applicability of the technique for thin-film analysis. Significantly, the presented technique opens new possibilities for nm depth profiling with high spatial resolution in scanning electron microscopes.