Essential Aspects of Negative Bias Temperature Instability (NBTI)

By Ahmad Ehteshamul Islam1, Souvik Mahapatra2, Muhammad Alam3

1. University of Illinois at Urbana-Champaign 2. Indian Institute of Technology Bombay 3. Purdue University

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We develop a comprehensive theoretical framework for explaining the key and characteristic experimental signatures of NBTI. The framework is based on an uncorrelated dynamics of interface-defect creation/annihilation described by Reaction-Diffusion (R-D) theory and hole trapping/detrapping into/out-of oxide defects based on a generalized Shockley-Read-Hall model. The proposed theory can consistently explain the long-term stress-phase power-law time exponent, stress/relaxation-phase temperature dependence, characteristic feature of duty-cycle dependence, and universal feature of frequency independence - measured in DC and AC stress conditions over a wide variety of transistors. Thus, we confirm the general validity of R-D theory in explaining the universal features (irrespective of dielectric material) of both DC and AC NBTI. The non-universal features of NBTI have correlation with the amount of oxide defects within the dielectric and do not affect AC NBTI measurements at lower duty cycle. Decomposition of these (uncorrelated) universal and non-universal components is, therefore, essential before comparison with any theory.


The work is an accumulation of our last few years research on NBTI. It has been immensely benefited from the discussion with/contribution from D. Varghese, N. Kumar, H. Kufluoglu, A. Krishnan, J. H. Lee, A. Oates, A. Jain, K. Ahmed, C. Olsen, E. Murakami, H. Aono, M. Masuduzzaman, G. Gupta, and H. Das.

Sponsored by

Applied Materials, Inc.
Taiwan Semiconductor Manufacturing Corporation
2008 IEEE EDS PhD Fellowship
2009-2010 Intel Foundation PhD Fellowship


A.E. Islam, S. Mahapatra, S. Deora, V.D. Maheta, and M.A. Alam, "Essential Aspects of Negative Bias Temperature Instability (NBTI)", in Silicon Nitride, Silicon Dioxide, and Emerging Dielectrics, R. E. Sah, J. Zhang, J. Deen, J. Yota and A. Toriumi, Editors, vol. 4, p. 145-174, The Electrochemical Society Proceedings Series (2011).

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Researchers should cite this work as follows:

  • Ahmad Ehteshamul Islam, Souvik Mahapatra, Muhammad Alam (2011), "Essential Aspects of Negative Bias Temperature Instability (NBTI),"

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