Differential Aging Sensor Using Subthreshold Leakage Current to Detect Recycled ICs

Electronic system components can fall prey to counterfeiting via untrustworthy parties in the semiconductor supply chain, which has established a worldwide span to reduce costs, time to market, and increase productivity. Recently, integrated circuits (ICs) counterfeiting has threatened systems security and reliability that utilize ICs in all domains. This article focuses on the most counterfeited area—recycled and remarked ICs—and aims to develop a technique to distinguish between new and used digital ICs based on an aging sensor mechanism. Aging sensors have been studied based on path-delay fingerprinting and ring oscillators (ROs) frequency degradation, but their resolution requires further development to accurately detect short usage. This study proposes a novel differential aging sensor to measure the discharge time ( $\tau {{{dv}}}$ ) increase that depends on the subthreshold leakage current due to aging with two on-chip designs. Simulations were conducted using the GlobalFoundries (GF) 22 nm for aging with bias temperature instability and hot carrier injection (HCI) combined. The results show that the $\tau {{{dv}}}$ increase is 14.72% after 15 days of usage and increases to 60.49% after three years. This further increases at higher temperatures; the highest simulated temperature ( $125~^{\circ }\text{C}$ ) $\tau {{{dv}}}$ increases by 55.93% after 15 days and 310.17% after three years. The proposed method also outperformed the traditional frequency degradation-based aging estimation method, which at nominal temperature is found to be 5.00% after 15 days and 23.68% after three years. Therefore, discharge time is a sensitive indicator for aging, surpasses frequency in detecting previous usage and is robust against process, voltage, and temperature variations (PVTs).