Silicon-carbon source and drain stressors: Carbon profile design by ion implantation

Abstract

We investigated Si:C SD 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 SD stressors and achieves more than 30% reduction of sheet resistance (R s) when SPE temperature is lower than 800°C. Samples with retrograde carbon profile have a lower R s for a given substitutional carbon concentration compared to the uniform carbon profile samples. Nickel monosilicide (NiSi) formed on Si:C SD with a retrograde carbon profile has a R s which ∼10 lower than that formed on Si:C with uniform C profile. © 2012 The Electrochemical Society.