A reliability model for CMOS circuit based on device degradation

CMOS device degradations such as negative bias temperature instability (NBTI) and hot carrier injection (HCI) have been extensively investigated. However, the relationship between the device degradation and the circuit reliability is not well established. In this paper, we propose a model for the frequency degradation of the ring oscillator (RO) after static stress based on the device degradations of NBTI. The model is demonstrated by using the SMIC 65nm technology. We found that the frequency degradation is much significant for the RO consisting of short (60 nm) channel devices as compared to that of long (130 nm) channel devices. The difference is essentially due to the HCI which dominates the degradation of the RO consisting of short channel devices. Combine the proposed model and the frequency degradation of the RO under dynamic stress, the contribution of NBTI and HCI is distinguished.