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

Abstract

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 Φ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bn</i> 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 Φ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bn</i> 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 Φ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bn</i> . 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.