Distribution and properties of oxide precipitates in annealed nitrogen doped 300 mm Si wafers

Spatial distribution and properties of oxide were examined in 300 mm nitrogen (N) doped CZ-Si. Experimentally grown materials with N ranging from ~ 1013 cm−3 to 1015 cm−3 were studied by infrared light scattering tomography, scanning infrared microscopy, transmission electron microscopy and electron beam induced current. It was established that an increasing N content improves the uniformity of the radial distribution of precipitates in the bulk of the wafer, the density of precipitates reaching a level of ~ 109 cm−3. The width of the denuded zone varies in the range from $15\;\mu$m to $70\;\mu$m depending on radial position and N doping level. Electron microscopy revealed lower oxide precipitate densities of about 105 to 108 cm−3. The results are interpreted in terms of existence of agglomerates of nanometer size precipitate nuclei and/or by the defect-induced strain relaxation around the precipitates