$\mathrm{Si}/\mathrm{Cu}$ Interface Structure and Adhesion

An ab initio investigation of the $\mathrm{Si}(111)/\mathrm{Cu}(111)$ interfacial atomic structure and adhesion is reported. Misfit dislocations appear naturally, as do hcp interfacial silicide phases that vary with temperature. The silicides form in the interface even at relatively low temperatures. These results are consistent with available experimental data.

Figure 1

The $\mathrm{Si}(111)\mathrm{\text{/}}\mathrm{Cu}(111)$ interface phase structures with temperature. $\mathbf{A}$, $\mathbf{B}$, and $\mathbf{C}$ indicate the different phases. Phase $\mathbf{A}$ exists below 300 K, phase $\mathbf{B}$ exists for $300\mathrm{K}<T<1160\mathrm{K}$, while the transition to phase $\mathbf{C}$ occurs at 1160 K. The black balls represent the Si atoms, and the light-colored balls the Cu atoms. The vertical dotted lines indicate the boundaries of the supercell employed. The horizontal dashed lines indicate the potential fracture planes and the corresponding work of separation is given in $\mathrm{J}/{\mathrm{m}}^2$. The layer numbering system is shown as L1 for the first layer that is entirely Si atoms and L7 for the first layer of entirely Cu atoms.

Figure 2

The top view of the corresponding interface $\mathrm{Si}/\mathrm{Cu}$ mixing layers L2 (see Fig. 1), of phases $\mathbf{A}$, $\mathbf{B}$, and $\mathbf{C}$. The black balls represent the Si atoms, and the light-colored balls the Cu atoms. The supercell cross section is outlined in black.