Trigger-When-Charged: A technique for directly measuring RTN and BTI-induced threshold voltage fluctuation under use-V dd

• Published in: IEEE Transactions on Electron Devices
• Main Author: Manut A.; Gao R.; Zhang J.F.; Ji Z.; Mehedi M.; Zhang W.D.; Vigar D.; Asenov A.; Kaczer B.
• Format: Article
• Language: English
• Published: Institute of Electrical and Electronics Engineers Inc. 2019
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062260875&doi=10.1109%2fTED.2019.2895700&partnerID=40&md5=06254a4dea8397fa464695ad2af93108
• ISSN: 189383
• DOI: 10.1109/TED.2019.2895700

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 ΔI d and threshold voltage ΔV th . Many early works, however, only measured RTN-induced ΔI d. ΔV th was not directly measured because of two difficulties: its average value is low and it is highly dynamic. Early works often estimated ΔV th from ΔI d /g m (V g = Vdd ), where g m 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 ΔV th . 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 ΔI d /g m (V g = V dd ) and the directly measured ΔV th (V g = V th ). 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 device-to-device variations of the directly measured RTN-induced ΔV th without selecting devices. © 2019 IEEE.