Systematic analysis of energy and delay impact of very deep submicron process variability effects in embedded SRAM modules

Variability is becoming a serious problem in process technology for nanometer technology nodes. The increasing difficulty in controlling the uniformity of critical process parameters (e.g. doping levels) in the smaller devices, makes the electrical properties of such scaled devices much less predictable than in the past. In this paper, we study how these technology effects influence the energy and delay of a SRAM module. Despite the implications in the correct operation of the module, in practically all cases the affected memory implementations become also slower while consuming on average more energy than nominally. This is partly counter-intuitive and no existing literature describes this in a systematic generic way for SRAMs. In this paper, we identify and illustrate the different mechanisms behind this unexpected behavior and quantify the impact of these effects for on-chip SRAMs at the 65 nm technology node.