Highly conductive Sb-doped layers in strained Si

The ability to create stable, highly conductive ultrashallow doped regions is a key requirement for future silicon-based devices. It is shown that biaxial tensile strain reduces the sheet resistance of highly doped $n$-type layers created by Sb or As implantation. The improvement is stronger with Sb, leading to a reversal in the relative doping efficiency of these $n$-type impurities. For Sb, the primary effect is a strong enhancement of activation as a function of tensile strain. At low processing temperatures, 0.7% strain more than doubles Sb activation, while enabling the formation of stable, $∼10-nm$-deep junctions. This makes Sb an interesting alternative to As for ultrashallow junctions in strain-engineered complementary metal-oxide-semiconductor devices.