It was recalled that the C-doping of Si was of great interest because, at high concentrations (greater than 1018/cm3), the C could reduce or suppress undesirable B diffusion in Si-based bipolar transistors. In order to understand this macroscopic behavior, the processes of point-defect interaction between dopants, vacancies and self-interstitials had to be analyzed. The reduction of B diffusion by C was known to be due to

the creation of a self-interstitial undersaturation. The influence of an over-saturation of vacancies, which was also produced by a high C concentration during annealing, was considered. Experiments on a vacancy-diffusing dopant (Sb) were used to prove this effect. Thus, in a C-rich sample, the Sb diffusivity was enhanced about 8 times as compared with samples with a much lower C concentration. An investigation was also made of C co-precipitation with O. This affinity was explained in terms of an exchange of point defects, and volume compensation.

Engineering the Diffusion Behavior of Dopants (B, Sb) in Silicon by Incorporation of Carbon. P.Lavéant, P.Werner, N.Engler, U.Gösele: Nuclear Instruments and Methods in Physics Research B, 2002, 186[1-4], 292-7