Local atomic structure and electrical properties of nitrided SiSiO2 interfaces produced by low-temperature plasma processing and rapid thermal annealing, and explained by ab-initio quantum chemistry calculations

This paper discusses the effectiveness of nitrogen (N-) atom incorporation at SiSiO2 interfaces in improving device reliability. N-atoms are introduced by a low thermal budget process that includes: (i) a 300°C plasma-assisted oxidation/nitridation; (ii) a 300°C plasma-assisted deposition of the dielectric layer; and (iii) a 900°C post-deposition anneal, either as a separate 30 s rapid thermal annealing (RTA) step, or during dopant activation of the gate electrode. The amount of incorporated-N has been varied at the monolayer range by using N2OO2 mixtures for the oxidation step, and has been measured by Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), and optical second harmonic generation (OSHG). A model, based on ab-initio calculations, is used to explain the role of N-atoms in improving device reliability, e.g. in reducing H-atom induced generation of positively-charged defects, the so-called anomalous positive charge (APC).