Performance, Power, and Area of Standard Cells in Sub 3 nm Node Using Buried Power Rail

Abstract

We analyzed the performance, power, area of 3 nm node fin and nanosheet (NS) field-effect transistors (FETs) implementing buried power rail (BPR) after full calibration to 5 nm node hardware. Fin-shaped FETs (FinFETs) have smaller <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> delay than do NS FETs (NSFETs) under the same footprint and two-fin configuration. Larger number of NS channels boost drive currents but also increase gate capacitances as a tradeoff. Compared with 7 and 3 nm standard cells achieve 75% cell area scaling in average. Cells using BPR decrease delay, transition time, internal power, and pin capacitances under the same area. Larger cells such as D-flip flop (DFF) and XOR decrease those further because the parasitic capacitances of metal layers between signal and power/ground decrease much. NS-based cells using BPR can improve delay and transition time by increasing the number of NS channels, but increase internal power and pin capacitance. Overall, fin-based cells using BPR have smaller energy delay product by 12% compared with those without BPR and by 10% compared with NS-based cells using BPR.