Auger and XPS characterization of a multi layered Ti–Co–Si system for self aligned silicides purposes: a stoichiometry and chemical investigation

Self-aligned silicides, as the Co–Si system for less than 0.13 μm applications, are still under investigation, due to some lack of their structural and basic characteristics knowledge. Due to oxygen contamination, originated by a number of possible sources, an outermost capping layer is required to ensure that no oxygen can easily enter the network, altering the thermodynamic properties of the film itself, when performing any thermal treatment. With this in mind, in this work we present an Auger electron spectroscopy (AES) and an X-ray photoelectron spectroscopy (XPS) investigation on a Ti–Co–Si layered system, thermally treated in the range 1023–1103 K, to evaluate the apparent stoichiometry and the chemical role of the components after making some RTP procedures. It turned out that the Ti cap layer has functioned as a good oxygen barrier diffusion at this temperature range, while part of the remaining Ti is present into the Co–Si matrix, having formed a ternary compound as Ti4,5 Si1,9 Co. Finally, in the Co silicide region a Si 2p3/2 peak shape variation ascribed to the silicide has been identified; this variation has been considered as a fingerprint of the compound itself.