Fachbereich 11 - Physik
Institut für Materialphysik
Diffusion and Defects in Elementary and Compound Semiconductors

Impact of high boron doping levels and
oxygen concentrations on the diffusion of gold in silicon

Experiments on the diffusion of gold in undoped silicon are known to provide information about the contribution of self-interstitials to silicon self-diffusion under intrinsic conditions. These former experiments demonstrate the usefulness of gold as a probe atom for studying the properties of native defects in silicon. In order to investigate the impact of high boron doping levels on gold diffusion, we performed diffusion experiments of gold in homogeneously boron doped silicon single crystal. Silicon crystal with various boron doping levels grown by the Czochralski technique were used for our diffusion experiments. After diffusion the gold profiles were determined by means of the neutron activation analysis in conjunction with serial sectioning and counting the specific activity of each section. Numerical analysis of the gold profiles reveal that singly positively charged self-interstitials mainly mediate self-diffusion under p-type doping. Moreover, the fast component of gold diffusion is found to be caused by singly positively charged interstitial gold atoms. With increasing annealing time the formation of spherical oxygen precipitates with a diameter between 14 nm and 20 nm was detected with transmission electron microscopy. The formation of oxygen precipitates causes an injection of self-interstitials in the silicon bulk and as a consequence affects the diffusion behaviour of gold. The interference between precipitate formation and gold diffusion provides information about the rate of oxygen precipitate formation and about the rate interstitial gold is gettered at these microdefects.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft

Beteiligte Wissenschaftler:

HDoz. Dr. H. Bracht (project leader), Prof. Dr. H. Kohl (Physikalisches Institut, Universität Münster), Dipl. Phys. A. Rodriguez Schachtrup (Institut für Materialphysik, Universität Münster), Dipl. Phys. A.-K. Rokahr (Physikalisches Institut, Universität Münster), Dr. I. Yonenaga (Tohoku University, Sendai, Japan)

Veröffentlichungen:

A.-K. Rokahr: Untersuchung der Elementverteilung an Ausscheidungen mit Hilfe des energiefilternden Transmissionselektronenmikroskops (EFTEM), Diplomarbeit, Physikalisches Institut der Universität Münster (2002).

A. Rodriguez: Mechanismen der Diffusion von Gold in Silicium - Einfluss von Versetzungen, hohen Bordotierungen und Sauerstoffübersättigungen, Doktorarbeit, Institut für Metallforschung der Universität Münster (2003).