COMPARISON OF DEFECT STRUCTURE IN N2O- AND NH3-NITRIDED OXIDE DIELECTRICS

Electron spin resonance spectroscopy is used to identify and compare p oint defects in N2O-nitrided, NH3-nitrided, and conventional SiO2 film s. We detect only three types of defects in these dielectrics. P(b) ce nters, the primary source of interface states in S/SiO2 systems under all technologically significant circumstances, appear in all three die lectrics. Both N2O and NH3 nitridation result in higher as-processed P (b) interface defect densities, but lower radiation-induced P(b) defec t generation. Thus N2O nitridation appears capable, as does NH3 nitrid ation, of providing reduced radiation-induced interface state generati on. In addition, both nitridations appear capable of lowering the numb er of radiation-induced E' centers, the dominant hole trap in conventi onal thermal oxides. NH3 nitridation, however, appears to offer greate r resistance to radiation-induced generation of these traps. NH3 nitri dation also results in a large number of bridging nitrogen centers, an d strong evidence indicates that the bridging nitrogen centers are the dominant electron trap in NH3-nitrided and -reoxidized.nitrided oxide films. These defects are absent in N2O-nitrided films, which are know n to exhibit reduced levels of electron trapping.