Semiconductor device

A semiconductor device, comprising:

• a substrate;
• a first active pattern on the substrate and extending in a first direction;
• first source/drain patterns in recesses in an upper portion of the first active pattern;
• and
• a gate electrode on the first active pattern and extending in a second direction crossing the first direction,
• wherein:
• each of the first source/drain patterns includes a first semiconductor layer and a second semiconductor layer, which are sequentially provided in the recesses,
• the first active pattern includes a first channel pattern at an upper portion thereof,
• the first channel pattern includes a pair of first surfaces that face the first source/drain patterns, and a pair of second surfaces that connect the pair of first surfaces to each other and are overlapped with the gate electrode,
• the first semiconductor layer includes first portions on the first surfaces and second portions on the second surfaces, and
• the first portions of the first semiconductor layer is thicker than the second portions of the first semiconductor layer,
• the first channel pattern includes a plurality of first layers vertically stacked on the substrate,
• the plurality of first layers are connected to the first semiconductor layer.

A semiconductor device, comprising:

• a substrate;
• a first active pattern on the substrate and extending in a first direction, the first active pattern including a first channel pattern;
• first source/drain patterns in recesses in an upper portion of the first channel pattern;
• a gate electrode on the first active pattern and extending in a second direction crossing the first direction,
• an active contact connected to the first source/drain pattern;
• and
• an interface layer between the active contact and the first source/drain pattern,
• wherein:
• each of the first source/drain patterns includes a first semiconductor layer, and a second semiconductor layer, which are sequentially provided on the recesses,
• each of the first channel pattern, the first semiconductor layer, and the second semiconductor layer includes silicon-germanium (SiGe),
• a germanium concentration of the first semiconductor layer is higher than a germanium concentration of the second semiconductor layer,
• the first channel pattern includes a pair of first surfaces, which face the first source/drain patterns, and a pair of second surfaces, which connect the pair of first surfaces to each other and are overlapped with the gate electrode, and
• the first semiconductor layer includes first portions on the first surfaces and second portions on the second surfaces,
• the first channel pattern includes a plurality of first layers vertically stacked on the substrate,
• the plurality of first layers are connected to the first semiconductor layer.