Silicon-Carbon Source and Drain Stressors: Carbon Profile Design by Ion Implantation

Abstract

We investigated Si:C S/D stressors having a retrograde carbon profile formed by carbon ion implantation and solid phase epitaxy (SPE). The retrograde carbon profile features a 30-nm-thick buried silicon carbon (Si:C) layer that is spatially decoupled from a 10-nm-thick surface layer with high phosphorus concentration. Retrograde carbon profile can increase the dopant activation rate in the Si:C S/D stressors and achieves more than 30% reduction of sheet resistance (Rs) when SPE temperature is lower than 800°C. Samples with retrograde carbon profile have a lower Rs for a given substitutional carbon concentration compared to the uniform carbon profile samples. Nickel monosilicide (NiSi) formed on Si:C S/D with a retrograde carbon profile has a Rs which ∼10% lower than that formed on Si:C with uniform C profile.