Resilience of ultra-thin oxynitride films to percolative wear-out and reliability implications for high-κ stacks at low voltage stress
Lip Lo, Vui
Leong Pey, Kin
Date of Issue2013
School of Electrical and Electronic Engineering
Localized progressive wear-out and degradation of ultra-thin dielectrics around the oxygen vacancy percolation path formed during accelerated time dependent dielectric breakdown tests is a well-known phenomenon documented for silicon oxynitride (SiON) based gate stacks in metal oxide semiconductor field effect transistors. This progressive or post breakdown stage involves an initial phase characterized by “digital” random telegraph noise fluctuations followed by the wear-out of the percolation path, which results in an “analog” increase in the leakage current, culminating in a thermal runaway and hard breakdown. The relative contribution of the digital and analog phases of degradation at very low voltage stress in ultra-thin SiON (16 Å ´ ) is yet to be fully investigated, which represents the core of this study. We investigate the wear-out process by combining electrical and physical analysis evidences with modeling and simulation results using Kinetic Monte Carlo defect generation and multi-phonon trap assisted tunneling (PTAT) models. We show that the transition from the digital to the analog regime is governed by a critical voltage (VCRIT ), which determines the reliability margin in the post breakdown phase. Our results have a significant impact on the post-breakdown operational reliability of SiON and advanced high-κ–SiOx interfacial layer gate stacks, wherein the SiOx layer seems to be the weakest link for percolation event.
DRNTU::Engineering::Electrical and electronic engineering
Journal of applied physics
© 2013 AIP Publishing LLC. This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of AIP Publishing LLC. The paper can be found at the following official DOI: http://dx.doi.org/10.1063/1.4819445. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.