The Influence of Background Carbon Concentration on the Transient Enhanced Diffusion of Boron Tomoya Saito, Jianxin Xia, Ryangsu Kim, Takenori Aoki, Yoshikazu Furuta, Yoshinari Kamakura, Hiroyuki Kobayashi, and Kenji Taniguchi Department of Electronics and Information Systems, Graduate School of Engineering, Osaka University, Suita, 565-0871 Japan SUMMARY We have observed transient enhanced diffusion (TED) in silicon substrates with boron doping superlattices and varying background carbon concentrations after ion implantation with silicon ions followed by low-temperature annealing. Our results clarify the effects of low-level carbon concentrations on this process. In addition, we have found that the effective diffusion coefficient of self-interstitial Si atoms is inversely proportional to the square of the substrate carbon concentration. We also discovered that the carbon atoms segregate out in the ion-implantation damage re- gions, forming boroncarbon clusters. © 2002 Scripta Technica, Electron Comm Jpn Pt 2, 85(2): 5460, 2002; DOI 10.1002/ecjb.1093 Key words: Transient enhanced diffusion (TED); carbon atoms; boron, doping superlattice on silicon; carb - on-boron cluster. 1. Introduction Carbon atoms are present in silicon crystals as impu - rities substituting for silicon atoms. These carbon atoms generally are incorporated into substrates grown by CZ or FZ techniques at levels of 10 16 to 10 17 cm 3 . Many publish- ed papers [13] have discussed the structure of carbon atoms in silicon, and how they behave in the crystal lattice. These incorporated carbon atoms can also efficiently cap- ture self-interstitial Si atoms, thereby exerting an important influence on impurity diffusion. Because carbon atoms can capture self-interstitial Si atoms created by ion implanta- tion, there are many regions in which the total number of these Si atoms is depleted, which suppresses TED (Tran- sient Enhanced Diffusion) [4]. At the time the annealing begins, the self-interstitial Si atoms coexist with other types of impurity defects, such as single boron atoms, line defects, impurity pairs, and so on, all generated by ion implantation. The TED phenome- non indicates an enormous increase in the quasi-equilib - rium diffusion coefficient of a defect species, by factors of a thousand to ten thousand, over its equilibrium value. During the early stages of the annealing, the self-interstitial Si atoms generated by the implantation aggregate to form {311} defects [5]. Because these {311} defects grow by capturing self-interstitial Si atoms one by one, they control the spatial distribution of these atoms [6, 7]. Because of this mechanism, the generation and decomposition rates of {311} defects are closely related to the phenomenon of impurity diffusion mediated by self-interstitial Si atoms. However, when ion implantation is used to introduce self- interstitial Si atoms into a silicon crystal substrate, direct measurements are difficult [811]. In our research, we studied boron marker layers with a six-layer doping superlattice structure, grown on silicon substrates with varying substrate carbon concentrations. In © 2002 Scripta Technica Electronics and Communications in Japan, Part 2, Vol. 85, No. 2, 2002 Translated from Denshi Joho Tsushin Gakkai Ronbunshi, Vol. J83-C-I, No. 8, August 2000, pp. 74 4748 Contract grant sponsor: Semiconductor Technology and Research Center 54