A perspective on today’s scaling challenges and possible future directions

Progress in scaling of MOS transistors and integrated circuits over the years is reviewed and today’s status and challenges are described. Generalized scaling is updated for the present leakage-constrained environment to project results of continued scaling at a constant power-supply voltage. Alternatives to achieve energy-efficient operation at lower voltages are discussed. Particular attention is given to threshold variability issues and to the design challenges in reducing and controlling variability using back-gate devices. The importance of the depth of the inversion layer below the silicon surface as a limit to the effectiveness of gate-insulator scaling is illustrated by a design study. Low-temperature operation is considered as a possible future direction for continuing scaling.