Negative-bias temperature instability – insight from recent dynamic stress experiments
Ang, Diing Shenp
Boo, A. A.
Date of Issue2013
School of Electrical and Electronic Engineering
The purpose of this paper is to summarize key experimental evidences on the important role of hole trapping on negative-bias temperature instability (NBTI). For a long time, the focus of this research topic had been on interface degradation driven by hydrogen transport and hole trapping was regarded as a side effect arising out of fast measurement techniques proposed to mitigate the effect of recovery on measurement data. In recent studies, we showed that the threshold voltage (Vt) fluctuations one typically observed under dynamic NBTI were mainly the result of hole trapping and not hydrogen-transport driven interface-state generation/passivation proposed earlier. In particular, the cyclical Vt shifts and constant Vt recovery are inconsistent with the basic principle of the hydrogen transport model. Such behaviors are better described in terms of hole trapping/detrapping at pre-existing oxide defects. We have also shown that interface degradation during NBTI stressing has no apparent impact on bulk (oxide) trap generation, i.e. interface trap generation does not lead to bulk trap generation. This result raises further questions on the validity of the hydrogen transport mechanism and the long standing hypothesis on hydrogen-induced bulk trap generation and gate oxide breakdown. Finally, it is shown that the transient hole trapping responsible for the Vt shift fluctuations could be transformed into more permanent trapped holes under NBTI stressing. The extent of transformation is accelerated by a high oxide field and temperature. An excellent correlation with stress induced leakage current indicates that such transformation underlie the generation of bulk traps reported by earlier studies.
DRNTU::Engineering::Electrical and electronic engineering
© 2013 The Electrochemical Society. This paper was published in ECS Transactions and is made available as an electronic reprint (preprint) with permission of The Electrochemical Society. The paper can be found at the following official DOI: [http://dx.doi.org/10.1149/05201.0073ecst]. 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.