Investigation of metal-gate work-function variability in FinFET structures and implications for SRAM cell design

In sub-20 nm CMOS technology nodes, the parameter variability has become a main hurdle during the scaling of devices. Recently, the use of metal gate stacks in nano-scale FinFET structure has a significant impact on the intrinsic parameter fluctuations due to the granular nature of metals. A 14 nm FinFET structure has been considered to study the impact of metal-gate work-function variability by using the 3-D device and mixed mode circuit simulation. The present work investigates the impact of work function variability (WFV) on electrical characteristics of various possible FinFET architectures followed by the regression model. Further, the investigation has been extended to study the stability performance of 6-T SRAM cell under the influence of WFV. It is observed that work function variation may result in considerable performance degradation in device as well as SRAM operation in nano domain.