Semiconductor device

A semiconductor device comprising:

• a substrate comprising an n-type metal-oxide-semiconductor field-effect transistor (NMOS) region;
• an active pattern extending in a first horizontal direction on the substrate;
• a plurality of nanosheets stacked on the active pattern and spaced apart from each other in a vertical direction;
• a gate electrode on the active pattern and surrounding the plurality of nanosheets, wherein the gate electrode extends in a second horizontal direction different from the first horizontal direction;
• a source/drain trench on the active pattern adjacent the gate electrode;
• and
• a source/drain region in the source/drain trench,
• wherein the source/drain region comprises:
• a first layer provided along a sidewall and a bottom surface of the source/drain trench, the first layer having a first n-type impurity doped therein;
• a second layer on the first layer in the source/drain trench, the second layer having germanium (Ge) doped therein;
• and
• a third layer filling a remaining portion of the source/drain trench on the second layer, the third layer having a second n-type impurity doped therein.