Device and circuit level suppression techniques for random-dopant-induced static noise margin fluctuation in 16-nm-gate SRAM cell

Abstract

In this study, a three-dimensional “atomistic” coupled device-circuit simulation is performed to explore the impact of process-variation-effect (PVE) and random-dopant-fluctuation (RDF) on static noise margin (SNM) of 16-nm complementary metal–oxide–semiconductor (CMOS) static random access memory (SRAM) cells. Fluctuation suppression approaches, based on circuit and device viewpoints, are further implemented to examine the associated characteristics in 16-nm-gate SRAM cells. From the circuit viewpoint, the SNM of 8T planar SRAM is enlarged to 230 mV and the variation of SNM ( σ SNM) is reduced to 22 mV at a cost of 30% extra chip area. As for device level improvement, silicon-on-insulator (SOI) FinFETs replaced the planar MOSFETs in 6T SRAM is further examined. The SNM of 6T SOI FinFETs SRAM is 125 mV and the σ SNM is suppressed significantly to 5.4 mV. However, development of fabrication process for SOI FinFET SRAM is crucial for sub-22 nm technology era.