Self-triggering hardware trojan: Due to NBTI related aging in 3-D ICs

3-D ICs provide more transistor density and higher performance at smaller area compared to traditional 2-D ICs. However, elevated temperatures and longer heat dissipation paths in 3-D IC can lead to non-ideal delay variations. Higher temperatures lead to negative bias temperature instability (NBTI), and consequently shifts threshold voltage (Vth), which leads to current degradation and delay increment. These variations can be exploited by hardware intruder and introduce malicious circuit components causing malfunctioning in 3-D ICs. This paper takes the threat model in which the attacker has access to the hard-intellectual property (IP) development, and defender is at the foundry. This paper demonstrates that a hardware intruder can leverage the exacerbated NBTI effect to trigger the Trojan payload. Consequently, such Trojans does not require a conventional triggering circuit; hence we named it as self-triggered. The proposed hardware Trojan is very difficult to detect and can scape various countermeasures at testing phase due to 'non-existing triggering signal'. The point of attack for the proposed Trojan is the body of the semiconductor device, for example, the body of PMOS device. When the Trojan gets activated it shorts the body and source of the PMOS to ground leading the device without power supply. We discussed the stealthy nature of our proposed Trojan against the existing countermeasures and also provided a discussion on a novel avenue of detecting such kinds of hardware Trojans.