Process reliability based trojans through NBTI and HCI effects

In this paper, we introduce the notion of process reliability based trojans which reduce the reliability of integrated circuits through malicious alterations of the manufacturing process conditions. In contrast to hardware/software trojans which either alter the circuitry or functionality of the IC respectively, the process reliability trojans appear as a result of alterations in the fabrication process steps. The reduction in reliability is caused by acceleration of the wearing out mechanisms for CMOS transistors, such as Negative Bias Temperature Instability (NBTI) or Hot Carrier Injection (HCI). The minor manufacturing process changes can result in creation of infected ICs with a much shorter lifetime that are difficult to detect. Such infected ICs fail prematurely and might lead to catastrophic consequences. The paper describes possible process alterations for both NBTI and HCI mechanisms that might result in creation of process reliability trojans. The paper also explores some possible detection techniques that can help identify the hidden trojans and discusses the various scenarios when process reliability based trojans lead to severe damages.