Trivalent siliconPb0andPb1defects were identified at both the top Si(100)/buried‐SiO2and buried‐SiO2/bottom‐Si(100) interfaces in high‐temperature (1320 °C) annealed Si/SiO2/Si struc‐ tures. The paramagnetic defects are generated by annealing in a flow of pure nitrogen (N2) or forming gas [N2H2; 95:5 (by volume)] at 550 °C. In addition, the forming‐gas anneal also generated positive charge in the buried oxides; significant lateral nonuniformities in the buried oxide charge density were observed following this anneal. These macroscopic inhomogeneities may be linked to previous reports of homogeneity related problems involving the SIMOX buried oxide, such as early breakdown and etch pits, suggesting that these types of measurements may be useful as nondestructive screens of SIMOX wafer quality. ©1996 American Institute of Physics.