An on-die digital aging monitor against HCI and xBTI in 16 nm Fin-FET bulk CMOS technology

Abstract

We propose an on-die aging monitor based on ring-oscillator (RO) which measures bias-temperature-instabilities (BTI) and AC hot-carrier-infection (HCI). The monitor consists of a symmetric RO (SRO) and an asymmetric RO (ASRO). The effect of NBTI and PBTI can be separated by focusing on the difference in sensitivity observed in SRO and ASRO under DC stress condition. In addition, the speed degradation caused by AC-HCI is monitored because unbalanced delay with long/short transition in ASRO has high sensitivity against AC-HCI under AC stress. A test chip including both SRO and ASRO using 2NAND standard cells is implemented in a 16 nm Fin-FET bulk CMOS technology. We observe that Vth shift due to PBTI measured from frequency degradation is 2 mV, which is still 1/10 of NBTI in Fin-FET technology. The measured AC-HCI shows almost half percentage of all aging factors. The aging monitor optimizes the design guard band (GB) in design phase and enables dependable system in high performance application LSIs.