A distinguishing property of copper impurities in silicon is their very fast diffusivity, which is undesirable in silicon device processes. This paper is the first attempt to simulate the fast diffusion of Cu by first-principles calculations. It is shown that, even near room temperature, the amplitude of Cu vibrations is very large; this is a consequence of the fact that the local mode of Cu has very low frequencies. At T>1000 K, the simulations demonstrate clear migration between adjacent cells. The diffusion path is from an interstitial T site to the next T site through an H site. The Arrhenius plot of the calculated diffusion constants agrees with the experimental data on the intrinsic diffusion of Cu, which are currently most reliable data available.

In the silicon device process, there is a strong demand for eliminating copper contamination. Gettering of Cu by dopant atoms is a useful method for this purpose. In this paper, the gettering of Cu is theoretically studied. We have assessed the efficiency of gettering through the evaluation of the binding energies between Cu and electronic dopants and the dissociation energies. The calculated dissociation energies well describe the efficiency of various dopants, which have been found experimentally. It is shown that B and Al are the most efficient gettering centers among single dopants. The present study provides the basis for further study of the gettering mechanism and for the design of efficient gettering centers.

No abstract