Oxygen precipitation in silicon: Experimental studies and theoretical investigations within the classical theory of nucleation

Quantitative measurements of the oxygen precipitate rate as a function of a nnealing were made in Czochralski-grown silicon wafers that contained diffe rent initial concentrations of oxygen. All wafers were annealed at 1000 deg rees C for 15 min to ensure that the initial cluster-size distributions wer e identical in all samples of the same composition prior to the multi-step annealing treatments used for the precipitation studies. The experimental d ata are compared with numerical predictions for time-dependent nucleation w ithin the classical theory of nucleation. Quantitative agreement is obtaine d between the measured and calculated densities of oxygen precipitates for nucleation temperatures greater than 600 degrees C, but only over a narrow range of oxygen composition. Below 600 degrees C, the measured density for all samples is orders of magnitude larger than is predicted from the model. Further, the measured data show an anomalously small temperature dependenc e for the induction time for nucleation that does not scale with the diffus ion coefficient, as expected from the classical theory of nucleation. Funda mentally, the classical theory of nucleation cannot explain the time-depend ent nucleation of oxygen precipitates for temperatures below 650 degrees C. A possible reason is given. (C) 1999 American Institute of Physics. [S0021 -8979(99)01812-5].