Fin field-effect transistor device and methods of forming

Abstract

A method of forming a semiconductor device includes: forming a gate structure over a fin that protrudes above a substrate; forming a source/drain region over the fin adjacent to the gate structure; forming an interlayer dielectric (ILD) layer over the source/drain region around the gate structure; forming an opening in the ILD layer to expose the source/drain region; forming a silicide region and a barrier layer successively in the openings over the source/drain region, where the barrier layer includes silicon nitride; reducing a concentration of silicon nitride in a surface portion of the barrier layer exposed to the opening; after the reducing, forming a seed layer on the barrier layer; and forming an electrically conductive material on the seed layer to fill the opening.