Semiconductor devices

A semiconductor device comprising:

• an active pattern which includes a lower pattern that extends in a first direction, and a plurality of sheet patterns spaced apart from the lower pattern in a second direction that is perpendicular to the first direction;
• a plurality of gate structures which are on the lower pattern and spaced apart from each other in the first direction, each gate structure including a gate electrode and a gate insulating film;
• and
• a source/drain pattern which is between a pair of the gate structures that are adjacent to each other in the first direction, the source/drain pattern including a semiconductor insertion film, and a semiconductor filling film on the semiconductor insertion film,
• wherein the semiconductor insertion film and the semiconductor filling film include silicon-germanium,
• wherein a germanium fraction of the semiconductor insertion film is less than the germanium fraction of the semiconductor filling film,
• wherein the semiconductor insertion film includes an inner surface that is in contact with the semiconductor filling film, and an outer surface that faces the plurality of sheet patterns,
• wherein the outer surface of the semiconductor insertion film includes a plurality of first convex curved regions and a plurality of first concave curved regions, and
• wherein the outer surface of the semiconductor insertion film is not in contact with the plurality of sheet patterns.

A semiconductor device comprising:

• an active pattern which includes a lower pattern that extends in a first direction, and a plurality of sheet patterns spaced apart from the lower pattern in a second direction perpendicular to the first direction;
• a plurality of gate structures which are on the lower pattern and spaced apart in the first direction, each gate structure including a gate electrode and a gate insulating film;
• and
• a source/drain pattern which is between a pair of the gate structures that are adjacent to each other in the first direction,
• wherein each gate structure includes inner gate structure between the lower pattern and the sheet pattern in the second direction, and between each pair of the sheet patterns adjacent to each other in the second direction, each inner gate structure including the gate electrode and the gate insulating film,
• wherein the source/drain pattern includes a semiconductor liner film, a semiconductor filling film on the semiconductor liner film, and a semiconductor insertion film between the semiconductor liner film and the semiconductor filling film,
• wherein the semiconductor liner film, the semiconductor insertion film and the semiconductor filling film include silicon-germanium,
• wherein a germanium fraction of the semiconductor insertion film is greater than a germanium fraction of the semiconductor liner film and less than a germanium fraction of the semiconductor filling film,
• wherein the semiconductor liner film includes an outer surface which is in contact with the sheet pattern and the inner gate structure, and an inner surface which is in contact with the semiconductor insertion film, and
• wherein the inner surface of the semiconductor liner film includes a plurality of convex curved regions and a plurality of concave curved regions.