Semiconductor device

A semiconductor device, comprising:

• an active pattern including a lower pattern and sheet patterns, the sheet patterns being spaced apart from the lower pattern in a first direction;
• a gate structure on the lower pattern, the gate structure surrounding the sheet patterns and extending in a second direction, the gate structure including a gate electrode;
• a source/drain recess within the active pattern and on at least one side of the gate structure, the source/drain recess including an extension area between the lower pattern and the sheet patterns or between adjacent ones of the sheet patterns in the first direction, and a dimension in a third direction of the extension area increasing and then decreasing as the extension area extends away from the lower pattern;
• and
• a source/drain pattern filling the source/drain recess, the source/drain pattern including at least one stacking fault spaced apart from a top surface of the lower pattern.

A semiconductor device, comprising:

• a first active pattern including a first lower pattern and first sheet patterns, the first sheet patterns being spaced apart from the first lower pattern in a first direction;
• a second active pattern including a second lower pattern and second sheet patterns, the second sheet patterns being spaced apart from the second lower pattern in the first direction;
• a first gate structure on the first lower pattern, the first gate structure surrounding the first sheet patterns and extending in a second direction;
• a second gate structure on the second lower pattern, the second gate structure surrounding the second sheet patterns and extending in the second direction;
• a first source/drain recess in the first active pattern and on at least one side of the first gate structure;
• a second source/drain recess in the second active pattern and on at least one side of the second gate structure;
• a first source/drain pattern filling the first source/drain recess, the first source/drain pattern including a stacking fault non-overlapping the first lower pattern in a third direction;
• and
• a second source/drain pattern filling the second source/drain recess.