Recombination activity of oxide precipitates with iron decoration in silicon

Abstract

Oxide precipitates are common defects in Czochralski-grown silicon material, which introduce recombination centers and limit the subsequent device efficiency. Moreover, iron contamination in silicon is known to decorate the oxide precipitates and significantly increase their recombination activity. In this study, we aim to quantify this increased recombination activity by analyzing the injection-dependent lifetime spectroscopy (IDLS) of n-type Czochralski silicon wafers containing oxide precipitates with or without iron contamination. The previously reported energy levels and capture coefficient ratios of oxide precipitates in silicon [Murphy et al. (2012).] were found to provide a good fitting to our experimental data, for both samples with and without iron, which suggests that iron decoration is unlikely to change those defect parameters of oxide precipitates, confirming previous reports. The product of capture coefficient for holes and defect density was extracted for each defect, with a variety of process conditions being examined: oxide precipitate growth time, cooling rate after thermal anneal, and subsequent phosphorus diffusion gettering. Fe decoration of oxide precipitates was found to enhance the recombination rate, the extent of which is not related to the cooling rates used in this study. A longer oxide precipitate growth anneal was found to introduce more recombination centers, with the recombination rate being similarly enhanced after iron decoration. Lastly, a phosphorus diffusion gettering step can fully reverse the impact of iron decoration for the conditions applied in this study, which is likely due to the lack of large iron precipitates formed during the applied cooling processes. Show more