EM-based on-chip aging sensor for detection and prevention of counterfeit and recycled ICs

Abstract

The counterfeiting and recycled integrated circuits (ICs) has become a major security threat for commercial and military systems. In addition to the huge economic impacts, they post significant security and safety threats on those systems. In this paper, we propose a new lightweight on-chip aging sensor, which is based on the electromigration (EM)-induced aging effects for fast detection and prevention of recycled ICs. Our new EM-based aging sensor exploits the natural aging/failure mechanism of interconnect wires to time the aging of the chip. Compared with existing aging sensor, the new aging sensor can provide more accurate prediction of the chip usage time at smaller area footprints due to its simple structure. The new sensor is based on a newly proposed physics-based stress evolution model of EM effects for accurate prediction of the EM failure. As a result, we can design the interconnect wire structures based on copper interconnect technology so that the resulting wires will have detectable EM failure at a specific time with sufficient accuracy. In order to mitigate the problem of the inherent variations in the metal grain sizes and assess its impacts on the nucleation time of metal wires, a number of parallel properly structured wires are used in the sensor. The parameters of the wires are optimized using the new EM model. Our statistical and variational analysis shows that the proposed aging sensor can accurately predict the targeted failure times in the presence of both inherent uncertainties. Our study also shows that more parallel wires will lead to more accurate statistical predictions at costs of more areas.