Effect of back-surface polycrystalline silicon layer on oxygen precipitation in Czochralski silicon wafers

The depth profile of oxygen precipitates in silicon wafers has been investigated for a variety of back surface conditions and thermal treatments. The results clearly show localized enhancement of oxygen precipitation in the region close to back surface polycrystalline silicon layers. The depth profile of intentionally introduced stacking faults on cleaved planes has also been shown to vary and is attributed an enhancement in the absorption of silicon self-interstitials by the back surface polysilicon layer. Consequently, the results observed in this study strongly support the enhancement effect of vacancies on oxygen precipitation in silicon crystals.