Effect of Pregate Carbon Implant on Narrow Width Behavior and Performance of High-k Metal-Gate nMOS Transistors

This paper experimentally shows the reduction of anomalous narrow width effect (NWE) observed in gate-first high-k metal-gate (HKMG) nMOS transistors by using pregate carbon implants. The experiments are performed with different carbon implant doses and energies, in collaboration with a semiconductor foundry. The 28-nm gate-first HKMG CMOS technology is used as the baseline flow. The physical mechanisms responsible for this improvement are identified and explained in detail. It is further shown that the pregate carbon implant used to suppress the NWE also increases junction leakage, improves the device electrostatics, and improves the universal curve.