Wear‐out stress monitor utilising temperature and voltage sensitive ring oscillators. Issue 2 (15th January 2018)

• Record Type: Journal Article
• Authors: Takeuchi, Kan; Shimada, Masaki; Okagaki, Takeshi; Shibutani, Koji; Nii, Koji; Tsuchiya, Fumio
• Is Part Of: IET circuits, devices & systems. Volume 12:Issue 2(2018)
• Page Start: 182
• Page End: 188
• Publication Date: 2018-01-15
• Subjects: oscillators -- stress analysis -- mechanical strength -- electric breakdown -- automotive electronics -- microcontrollers; wear-out stress monitor -- voltage sensitive ring oscillators -- on-chip wear-out monitoring technique -- environmental condition monitoring -- digital circuit -- T-sensitive ring oscillator -- wear-out stress strength -- temperature conditions -- model-of-exponential dependence -- time-dependent dielectric breakdown -- total wear-out stress -- HKMG process -- T-VT-sensitive RO frequencies -- thermal activation energies -- automotive microcontrollers -- boosted voltages -- elevated temperatures -- advanced driver assistance systems -- size 28 nm; Electronic circuits -- Periodicals; Electronic systems -- Periodicals; 621.381505
• DOI: 10.1049/iet-cds.2017.0153
• Languages: English
• ISSNs: 1751-858X

Abstract

Abstract : The authors propose an on‐chip wear‐out monitoring technique, which is based on monitoring the environmental conditions experienced by a digital circuit. The frequency of the T‐sensitive ring oscillator (RO) emulates the wear‐out stress strength caused by the temperature conditions based on the model of exponential dependence of the stress on the inverse of temperatures. The frequency of the VT‐sensitive RO emulates the stress due to time‐dependent dielectric breakdown, which is stressed by voltages as well as temperatures. Thus, the accumulated counts driven by the ROs directly indicate the total wear‐out stress that the product has experienced so far. The measured results of a test chip fabricated by 28 nm High‐k Metal Gate process confirm the expected dependence of T‐/VT‐sensitive RO frequencies on temperatures and voltages, enabling the emulation of wear‐out. The methodology is presented to estimate the stress amount of various wear‐out factors having different thermal activation energies. The proposed wear‐out stress monitor would make automotive microcontrollers more reliable when they operate at boosted voltages and elevated temperatures to meet performance requirements of cutting‐edge applications such as advanced driver assistance systems.