Abruptness of Au-Si contacts with thin CoSi2 interlayers

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Abstract
High‐resolution synchrotron radiation photoelectron spectroscopy has been used to study Au/Si and Au/CoSi2/Si interface formation at room temperature. Our results show Au‐Si intermixing, the absence of a well defined Au‐Si compound, and surface segregation of small amounts of Si to the Au surface. An interlayer formed by the deposition of ≤3 Å of Co has relatively small effect on this Au‐Si atomic profile. Intermixing is abruptly quenched, however, when the Co deposition exceeds 3.5 Å, and a Au film free of Si can grow on the CoSi2 layer. These results demonstrate the effectiveness of CoSi2 layer as a barrier against Au‐Si intermixing and identify the critical coverage of Co needed to passivate the Si surface.