Electrical characterization of copper related defect reactions in silicon

Defect reactions involving interstitial copper impurities (Cu-i) in silicon are reviewed. The influence of the Coulomb interaction between positively charged copper and negatively charged defects, such as acceptor states of t ransition metals and lattice defects, on the complex formation rate is disc ussed in detail. The diffusivity of interstitial copper and the dissociatio n kinetics of copper-acceptor pairs are studied using the recently introduc ed transient ion drift (TID) method. TID results reveal that most interstit ial copper impurities remain dissolved immediately after the quench and for m pairs with shallow accepters. It is shown that in moderately and heavily doped silicon the diffusivity of copper is trap limited, while in low B-dop ed silicon the interstitial copper-acceptor pairing is weak enough to allow the assessment of the copper intrinsic diffusion coefficient. The intrinsi c diffusion barrier is estimated to be 0.18 +/- 0.01 eV. It is concluded th at the Coulomb potential used in previous publications underestimated consi derably the acceptor-copper interaction. In light of these results, a gener al discussion on Cu related defect reactions is given. +/- 1999 Elsevier Sc ience S.A. All rights reserved.