Semiconductor device having multi-bridge channel field-effect transistor including source/drain pattern with a plurality of semiconductor patterns

Abstract

A semiconductor device includes an active pattern including a lower pattern and a plurality of sheet patterns; a gate structure disposed on the lower pattern and surrounding the plurality of sheet patterns; and a source/drain pattern filling a source/drain recess formed on one side of the gate structure. The source/drain pattern includes a first semiconductor pattern extending along the source/drain recess and contacting the lower pattern, a second and third semiconductor patterns sequentially disposed on the first semiconductor pattern, a lower surface of the third semiconductor pattern is disposed below a lower surface of a lowermost sheet pattern, a side surface of the third semiconductor pattern includes a planar portion, and a thickness of the second semiconductor pattern on the lower surface of the third semiconductor pattern is different from a thickness of the second semiconductor pattern on the planar portion of the side surface of the third semiconductor pattern.