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 ∼ 10 13 cm -3 to 10 15 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 ∼ 10 9 cm -3 . The width of the denuded zone varies in the range from 15 μm to 70 μm depending on radial position and N doping level. Electron microscopy revealed lower oxide precipitate densities of about 10 5 to 10 8 cm -3 . The results are interpreted in terms of existence of agglomerates of nanometer size precipitate muclei and/or by the defect-induced strain relaxation around the precipitates.