The role of carbon on performance of strained-Si:C surface channel NMOSFETs

Carbon incorporation in strained-Si surface channel NMOSFET is investigated. Due to the ∼52% lattice mismatch between silicon and carbon, the channel is expected to have higher strain than strained-Si, indicating that the carrier mobility can be enhanced significantly. There is a ∼40% electron mobility enhancement for incorporated carbon content of 0.25% in strained-Si NMOSFETs compared to unstrained Si channels. The performance of channels with increased strain is not as high as theoretical predictions. This is due to the large Dit at the oxide/strained-Si:C interface and alloy scattering, which degrades carrier mobility enhancement.