OBSERVATION OF RING-OSF NUCLEI IN CZ-SI USING SHORT-TIME ANNEALING AND INFRARED LIGHT-SCATTERING TOMOGRAPHY

Small defects observed by IR light-scattering tomography after short-t ime annealing were shown to be related to the nuclei of ring-distribut ed oxidation-induced stacking faults (ring-OSF) in Czochralski-silicon crystals grown with growth rates of about 0.8 mm/min. The behavior of these defects was studied under different annealing conditions, and i t was found that they were already present in the as-grown crystal bel ow the detection limit of available techniques. Preannealing in nitrog en at 1150 degrees C introduced a stacking-fault-free region with subs equent oxidation. The reason for this was due neither to the annihilat ion of the ring-OSF nuclei nor to the formation of punched out disloca tion loops from precipitates during nitrogen ambient annealing, but pr obably due to a change in the nature of the OSF nuclei occurring, maki ng them incapable of OSF nucleation during subsequent oxidation. Vario us small defects were observed to exist in the as-grown crystal, and t he radial position of these defects depended on their critical size. T he distribution of as-grown defects within the crystal reflects the di fferences in the thermal stability of the defect nuclei due to point d efect variations in the crystal during growth.