Contact Technology for Strained nFinFETs With Silicon–Carbon Source/Drain Stressors Featuring Sulfur Implant and Segregation

In this work, strained n-channel FinFETs (nFinFETs) with silicon-carbon (Si:C) source/drain (S/D) stressors featuring NiSi:C contacts with segregated sulfur at the NiSi:C/Si:C interface are investigated in detail. The physical mechanism for the reduction in an effective Schottky barrier for electrons ΦBn due to presilicide sulfur ion implant and segregation is examined. The presence of sulfur near the NiSi:C/Si:C interface and its behavior as charged donor-like trap states was used to explain the enhancement of electron tunneling across the contact and the reduction in ΦBn down to 110 meV. New analysis using numerical simulation is presented. The results indicate that the presence of charged states near the interface plays a role in achieving low ΦBn. When the S-segregated NiSi:C contact was integrated in strained nFinFETs with Si:C S/D stressors, external series resistance is reduced, and the drive current is improved. The dependence of the drive current on fin width and gate length is also studied.