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 me asured by the spreading-resistance technique are well described within the framework of the kick-out mechanism involving generation of silic on self-interstitials, More specifically, the gold-incorporation rate appears to be controlled by the outdiffusion of excess self-interstiti als towards the surfaces. As a special feature, the measurements revea l a continuous increase of the gold boundary concentration which appro aches the pertaining solubility limit only after prolonged annealing. This can be interpreted in terms of a limited effectiveness of gold-al loyed {100} silicon surfaces as sinks for self-interstitials. The vali dity of this interpretation is supported by computer modeling of the e xperimental data yielding finite values for the self-interstitial surf ace-annihilation velocity. (C) 1998 American Institute of Physics. [S0 021-8979(98)04603-9].