Trigger-when-charged: a technique for directly measuring RTN and BTI-induced threshold voltage fluctuation under use-Vdd

Manut, A., Gao, R., Zhang, J. F., Ji, Z., Mehedi, M., Zhang, W. D., Vigar, D., Asenov, A. and Kaczer, B. (2019) Trigger-when-charged: a technique for directly measuring RTN and BTI-induced threshold voltage fluctuation under use-Vdd. IEEE Transactions on Electron Devices, 66(3), pp. 1482-1488. (doi: 10.1109/TED.2019.2895700)

Abstract

—Low-power circuits are important for many applications, such as Internet of Things. Device variations and fluctuations are challenging their design. Random telegraph noise (RTN) is an important source of fluctuation. To verify a design by simulation, one needs assessing the impact of fluctuation in both driving current Id and threshold voltage Vth. Many early works, however, only measured RTN-inducedId. Vth was not directly measured because of two difficulties: its average value is low and it is highly dynamic. Early works often estimated Vth from Id/gm(Vg = Vdd), where gm is the transconductance, without giving its accuracy. The objective of this paper is to develop a new Trigger-When-Charged (TWC) technique for directly measuring the RTN-induced Vth. By triggering the measurement only when a trap is charged, measurement accuracy is substantially improved. It is found that there is a poor correlation between Id/gm(Vg = Vdd) and the directly measured Vth (Vg = Vth). The former is twice of the latter on average. The origin for this difference is analyzed. For the first time, the TWC is applied to evaluate deviceto-device variations of the directly measured RTN-induced Vth without selecting devices.

• Item Type: Articles
• Additional Information: This work was supported by the Engineering and Physical Science Research Council of U.K. under Grant EP/L010607/1.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Asenov, Professor Asen
• Authors: Manut, A., Gao, R., Zhang, J. F., Ji, Z., Mehedi, M., Zhang, W. D., Vigar, D., Asenov, A., and Kaczer, B.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: IEEE Transactions on Electron Devices
• Publisher: IEEE
• ISSN: 0018-9383
• ISSN (Online): 1557-9646
• Published Online: 22 February 2019
• Copyright Holders: Copyright © 2019 IEEE
• First Published: First published in IEEE Transactions on Electron Devices 66(3): 1482-1488
• Publisher Policy: Reproduced in accordance with the publisher copyright policy