Radiation-induced defects in chemical-mechanical polished MOS oxides

Defect centers in chemical-mechanical polished MOS oxides generated by either X-ray irradiation or high-field stress have been characterized using electron paramagnetic resonance and C-V analysis. In X-ray irradiated samples equivalent densities of both oxide trap E´ and interface-trap P_b0 centers were detected in unpolished and polished oxides. In addition, significantly larger (6 times) densities of P_b1 centers were observed in irradiated chemical-mechanical polished oxides as opposed to unpolished oxides. This suggests that the polishing process alters the SiO₂/Si interface. However, the P_b1 centers detected in these samples do not respond electrically like conventional interface traps or border traps. This raises questions concerning the electrical and physical nature of P_b1 centers in these oxides. The high-field stress data showed no difference in the density of defect centers induced in polished and unpolished oxides P_b1 centers were not observed in either oxide following high-field stress