The technical assistance of Dave Elliott and Sylvain Laframboise and stimulating discussions with Ernie Kornelsen are acknowledged. SIMS measurements made using the CAMECA 3F facilities of Surface Western with the assistance of Garry Mount and the CAMECA 4F facilities of CANMET with the assistance of Jennifer Jackman.

The effect of antimony on oxygen precipitation and formation of the defect-free denuded zone in substrate and epitaxial wafers after a two-and a three-step anneal was studied. The results show that the formation of the denuded zone is strongly affected by the epitaxial deposition process and antimony doping concentration. In interpreting this observation, a model for the formation of the defect-free denuded zone accounting for the effect of strain-free energy has been developed. This model considers that "grown-in" microprecipitate nuclei play a significant role in the formation of the denuded zone. Using the proposed model, the dependence of denuded zone width on the antimony doping concentration is hypothesized to be due to an increase in the total free-energy of an isolated precipitate. Antimony when doped at a high concentration causes an increase in the shear property of silicon and, therefore, the total free-energy of oxygen precipitates. This, in turn, causes a retardation of precipitate growth, particularly in the subsurface region where oxygen is already undersaturated.

Substrate and epitaxial silicon wafers from silicon crystals containing oxygen concentrations ranging between 25 and 32 ppma were heat‐treated using one‐ and two‐step heat‐treatment processes. An epitaxial deposition thermal simulation heat‐treatment was also applied to the substrate wafers. The results indicate that a significant amount of preexisting microprecipitates are annihilated during the epitaxial deposition process, and the thermal history, as well as the growth conditions of the crystal, play an important role in the oxygen precipitation process. It is proposed that during epitaxial deposition, preexisting microprecipitates are dissolved by out‐diffusion of oxygen atoms from the precipitate particles as well as by the generation of excess self‐interstitials at the growing epitaxial surface, which results in retardation of the oxygen precipitation process.

The effect of the denudation anneal on the precipitate dissolution and defect-free zone formation in Czochralski silicon wafers after a three-step internal gettering anneal was studied. The results imply that the residual precipitates containing three or four oxygen atoms could be the predominant defects influencing the formation of the defect-free zone. Based upon the results from the process simulation model, it is proposed that some residual precipitates having a size less than the critical size could be in a metastable state at high temperatures. Thus during the denudation anneal, the precipitate dissolution occurs primarily in the subsurface region where the critical size is substantially increased due to the oxygen outdiffusion.

Photoluminescence at the photon energies of 0.808 and 0.874 eV was observed in silicon containing a high concentration of carbon after a two-step isochronal anneal. The annealing sequence consisted of a low-temperature isochronal anneal and a 1050 °C anneal, respectively. The observed luminescence had the photon energies corresponding to those of the D lines which are known to arise from the interstitial-type dislocation loops. In silicon containing a high concentration of carbon, a formation of the dislocation loops was hypothesized to occur via a condensation of the excess silicon interstitials, originated from the agglomerates of interstitial carbons.