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Formation and properties of the copper silicon(111) interface

1983; AIP Publishing; Volume: 1; Issue: 3 Linguagem: Inglês

10.1116/1.582596

2327-9877

F. Ringeisen, J. Derrien, E. Daugy, J.M. Layet, P. Mathiez, F. Salvan,

Semiconductor materials and devices

The initial stages of the Cu growth on top of a 7×7 Si(111) surface were monitored with LEED, AES, UPS, and XPS techniques. Results suggest that at room temperature the Cu growth proceeds by a laminar fashion. An intermixing between Si and Cu takes place giving rise to a diffuse interface extending to several first monolayers. This fact is testified by the splitting of the Si LVV transition in AES spectra, by the deviation of the AES and XPS Cu and Si signal plot versus coverage from a perfect layer by layer growth plot, and by a strong diffuse background intensity in LEED diagram. Moreover, at this coverage range, a slight narrowing and a shift (0.7 eV±0.2 eV) of the 3d Cu peak towards higher binding energy as compared with the bulk metal are observed in valence band photoemission spectra. With increasing coverage, a metal rich phase is found displaying an ordered 1×1 Cu(111) planelike structure. No Si enrichment at the topmost metallic layer is observed by XPS. Core level spectroscopy gives similar results showing a noticeable energy shift (0.6 eV±0.2 eV) for the Cu 2p line. A depth profile confirms the interface structure which is rather metastable at room temperature. At high temperature (T>400 °C), an ordered Cu induced pattern is found at θ∼1 monolayer. The diagram resembles a 5×5 superstructure. With increasing coverage, 3D crystallites are growing on top of the first ordered layer. The interface is stable at high temperature.