Modeling of transient point defect dynamics in Czochralski silicon crystals

Intrinsic point defects control the formation of grown-in defects in silico n crystals. Under stead?; state conditions, the type of the prevailing poin t defect species is exclusively determined by the ratio of pull rate and te mperature gradient in the crystal at the interface. In this study, simulati ons have been performed for transient growing processes where the pulling r ate has been abruptly changed. Large reservoirs of interstitials are formed in fast-grown. vacancy-rich crystals near the interface after abruptly red ucing the pulling rate for 30 min. During further growth at high pull rate, these interstitial reservoirs are transformed into large ellipsoidal defec t patterns. Experimental results are excellently reproduced if equilibrium concentrations are used as boundary conditions for interstitials and vacanc ies at all crystal surfaces. (C) 2001 Elsevier Science B.V. All rights rese rved.