Atomic-scale defects involved in NBTI in plasma-nitrided pMOSFETs

We utilize a combination of DC-IV measurements as well as two very sensitive electrically detected magnetic resonance measurements, spin-dependent recombination and spin dependent tunneling, to identify the atomic-scale defects involved in the negative bias temperature instability (NBTI) in 2.3 nm plasma- nitrided SiO₂-based pMOSFETs. Our measurements indicate that the NBTI-induced defect in the plasma-nitrided devices participates in both spin-dependent recombination and spin-dependent tunneling. The high sensitivity of our spin-dependent tunneling measurements allow for an identification of the physical and chemical nature of this defect through observations of ²⁹Si hyperfine interactions. We identify these defects as silicon dangling bond defects in which the central silicon is back bonded to nitrogen atoms. We assign these NBTI-induced defects as K_N centers because of their similarity to K centers observed in silicon nitride. The defect identification in plasma-nitrided devices helps to explain: (1) why NBTI is exacerbated in nitrided devices and (2) conflicting reports of NBTI induced interface states and/or bulk traps.