Diffusion of gold in silicon during rapid thermal annealing: Effectiveness of the surface as a sink for self-interstitials

Rapid thermal annealing was used for short-time diffusion experiments of gold in dislocation-free floating-zone silicon of {100} orientation at 1050 degrees C and 1119 degrees C. Concentration-depth profiles measured by the spreading-resistance technique are well described within the framework of the kick-out mechanism involving generation of silicon self-interstitials, More specifically, the gold-incorporation rate appears to be controlled by the outdiffusion of excess self-interstitials towards the surfaces. As a special feature, the measurements reveal a continuous increase of the gold boundary concentration which approaches the pertaining solubility limit only after prolonged annealing. This can be interpreted in terms of a limited effectiveness of gold-alloyed {100} silicon surfaces as sinks for self-interstitials. The validity of this interpretation is supported by computer modeling of the experimental data yielding finite values for the self-interstitial surface-annihilation velocity. (C) 1998 American Institute of Physics. [S0021-8979(98)04603-9].