Local atomic structure and electrical properties of nitrided SiSiO 2 interfaces produced by low-temperature plasma processing and rapid thermal annealing, and explained by ab-initio quantum chemistry calculations

Abstract

This paper discusses the effectiveness of nitrogen (N-) atom incorporation at SiSiO 2 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 N 2 O O 2 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).