Defect size and density distributions were obtained as a function of depth in N-doped Czochralski Si following high-low-high and low-high annealing, using an O precipitate profiler. The defects were also delineated by Wright etching and Nomarski optical microscopy on both cleaved and bevel polished samples. In addition to the enhanced

precipitation and absence of voids previously reported for N-doped Czochralski Si, an unexpected mode of precipitation was found near the annealed wafer surface, just above the traditional denuded zone. This oxynitride precipitate was considered with regard to N-related complex interactions and point defect supersaturation/injection. High-resolution transmission electron microscopy revealed that most precipitates had an octahedral shape with 2 distinct amorphous phases, which reflect a transition from an initial phase containing both N and O to one with primarily O, as verified with Z-contrast transmission electron microscopy and electron energy loss spectroscopy.

Role of Nitrogen Related Complexes in the Formation of Defects in Silicon. A.Karoui, F.S.Karoui, A.Kvit, G.A.Rozgonyi, D.Yang: Applied Physics Letters, 2002, 80[12], 2114-6