Based on Fourier transform infrared (FTIR) spectroscopy and bulk micro-defect investigations, in relation to earlier results of other groups, we suggest the following model for oxide precipitate nucleation in N-doped silicon. Around 600 degrees C a nucleation maximum exists where oxide precipitates are formed via oxygen attachment to both NOO and NNO complexes. These complexes are formed by the reaction of NN with interstitial oxygen. Vacancy supersaturation enhances this type of precipitate nucleation. A second nucleation maximum exists around 900 degrees C. This is assumed to be due to a vacancy assisted oxynitride SiOxNy based nucleation process. The higher density of the oxynitride phase compared to silicon oxide and a higher residual vacancy concentration would explain the observed shift of the maximum nucleation rate to higher temperatures around 900 degrees C. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nitrogen doping of CZ silicon results in an early formation of large precipitate nuclei during crystal cooling, which are stable at 900°C. These are prone to develop stacking faults and high densities of defects inside defect denuded zones of CZ silicon wafers. Simultaneous doping of FZ silicon with nitrogen and oxygen results in two main stages of precipitate nucleation during crystal cooling, an enhanced nucleation around 800°C, which is nitrogen induced, and a second enhancement around 600°C, which depends on the concentration of residual oxygen on interstitial sites. A combined technique of ramping with 1K/min from 500-1000°C with a final anneal at 1000°C for 2h and lateral BMD measurement by SIRM provides a possibility to delineate v/G on nitrogen-doped silicon wafers. Surface segregation of nitrogen and oxygen during out-diffusion can explain the enhanced BMD formation in about 105m depth and the suppressed BMD formation in about 405m depth below the surface. The precipitate growth is enhanced in regions where nitrogen is filled up again after a preceding out-diffusion.