Carrier transport in strained N-channel field effect transistors with channel proximate silicon-carbon source/drain stressors

Abstract

We investigate the carrier transport characteristics in strained n-channel metal-oxide-semiconductor field effect transistors (nFETs) with embedded silicon-carbon (Si:C) source/drain (S/D) stressors formed in close proximity to the channel, taking parasitic resistance into account in the extraction of carrier transport parameters. While bringing the Si:C S/D stressors closer to the channel improves their effectiveness in imparting tensile strain to the channel, degradation in ballistic efficiency due to increased carrier scattering is observed. Fortunately, this is more than compensated by an increase in the carrier injection velocity vinj. For channel-proximate (CP) Si:C S/D nFETs with gate lengths ranging from 100 to 130 nm, a ∼10% drive current IDsat enhancement is observed with a ∼15% improvement in v inj. These findings clarified experimentally that in addition to mobility enhancement, vinj improvement also plays a significant role in the IDsat enhancement achieved by CP Si:C S/D nFETs. © 2010 American Institute of Physics.