Semiconductor device and manufacturing method thereof

A semiconductor device, comprising:

• a substrate;
• an epitaxy feature on the substrate;
• a contact plug over the epitaxy feature and having a stepped sidewall structure comprising a lower sloped sidewall passing through a top surface of the epitaxy feature, an upper sloped sidewall, and an intermediary surface connecting the lower sloped sidewall to the upper sloped sidewall;
• a dielectric protection layer extending along the lower sloped sidewall of the contact plug and capped by the intermediary surface of the contact plug;
• a first inter-layer dielectric (ILD) layer enclosing the lower sloped sidewall of the stepped sidewall structure the contact plug;
• and
• a second inter-layer dielectric (ILD) layer over the first ILD layer and enclosing the upper sloped sidewall of the stepped sidewall structure of the contact plug, wherein the intermediary surface of the stepped sidewall structure of the contact plug forms an interface with the dielectric protection layer at a level higher than an interface formed by the first and second ILD layers.

A semiconductor device, comprising:

• a semiconductor fin protruding above a substrate;
• a gate electrode over the semiconductor fin;
• an epitaxy structure at least partially embedded in the semiconductor fin;
• a contact plug having a top end that overlaps the gate electrode and having a bottom end that is surrounded by the epitaxy structure;
• and
• a dielectric protection layer surrounding the contact plug and capped by the contact plug, wherein the dielectric protection layer and a topmost surface of the epitaxy structure forms an interface at a level higher than a top surface of the semiconductor fin.