Interfacial reaction and silicide formation in Pd/a‐Si:H layered films

Abstract

In this study, a layered film composed of Pd and hydrogenated amorphous silicon (a-Si:H) is thermally annealed at a constant heating rate, and the interfacial reaction as well as the formation mechanism of the Pd silicide (Pd2Si) are investigated by techniques such as hydrogen evolution, analysis, X-ray diffraction, and Rutherford backscattering spectrometry. The silicide formation reaction at the interface of Pd/a-Si:H is activated from approx. 250 °C. It is seen that Pd silicide in the amorphous state is generated at the initial stage of the reaction, which is gradually crystallized to grow to stable Pd2Si. Hydrogen is released in this silicide formation reaction, and the Pd2Si formation process is exactly reflected on the hydrogen evolution spectrum. As to the growth of Pd2Si, the following conjecture is made. The growth rate of Pd2Si is controlled by the interfacial reaction of Pd/a-Si:H at the initial stage where the Pd2Si layer is thin and by the diffusion of Pd in Pd2Si when the Pd2Si layer becomes thick. Based on these results, the Pd2Si formation model is proposed. Using the model, the reaction rate constant between Pd and a-Si:H, the diffusion constant of Pd in Pd2Si, and the growth rate of Pd2Si are investigated. The results of measurement agreed well with the results of previous reports, and demonstrated the validity of the model. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 2, 80(3): 12–22, 1997