Abstract:
A semiconductor device includes an active fin partially protruding from an isolation pattern on a substrate, a gate structure on the active fin, a source/drain layer on a portion of the active fin adjacent to the gate structure, a source/drain layer on a portion of the active fin adjacent to the gate structure, a metal silicide pattern on the source/drain layer, and a plug on the metal silicide pattern. The plug includes a second metal pattern, a metal nitride pattern contacting an upper surface of the metal silicide pattern and covering a bottom and a sidewall of the second metal pattern, and a first metal pattern on the metal silicide pattern, the first metal pattern covering an outer sidewall of the metal nitride pattern. A nitrogen concentration of the first metal pattern gradually decreases according to a distance from the outer sidewall of the metal nitride pattern.