Patent ID: 8659089

Claim:
A method comprising: providing a substrate; forming a gate structure over the substrate; forming a spacer liner on sidewalls of the gate structure, wherein the spacer liner is formed of a first material; forming a spacer over the spacer liner on the sidewalls of the gate structure, wherein the spacer is formed of a second material that is different than the first material; after forming the spacer over the spacer liner on the sidewalls of the gate structure, removing portions of the substrate to form a first recess and a second recess in the substrate, such that the gate structure interposes the first recess and the second recess; forming a nitrogen passivation layer in the substrate, such that the first recess and the second recess are defined by nitrogen passivated surfaces of the substrate, wherein the nitrogen passivation layer has a gradient nitrogen dopant profile such that nitrogen concentration increases from a top surface of the nitrogen passivation layer to an opposing bottom surface of the nitrogen passivation layer; and forming doped source and drain features over the nitrogen passivated surfaces of the first recess and the second recess, the doped source and drain features filling the first and second recesses.