Semiconductor device and manufacturing method thereof

Abstract

A method of forming a semiconductor device includes forming an epitaxial source/drain (S/D) structure adjacent to a gate structure; forming a dielectric structure over the gate and epitaxial S/D structures; forming a trench in the dielectric structure to accessibly expose a portion of the epitaxial S/D structure; forming a contact feature from the portion of the epitaxial S/D structure within the trench; and forming a S/D contact in the trench to be in contact with the contact feature overlying the epitaxial S/D structure. Forming the contact feature includes forming a metallic layer in the trench; performing a thermal process on the metallic layer to form the contact feature, where after the thermal process, metallic residues remain on a sidewall of a spacer of the dielectric structure in the trench; and removing the metallic residues by using a wet etching process, wherein the spacer of the dielectric structure remains substantially intact.