Semiconductor devices having source/drain regions

A semiconductor device comprising:

• a substrate having a first fin active region pattern and a second fin active region pattern, each of which has a protruding shape;
• a device isolation layer pattern covering a side surface of a lower portion of each of the first fin active region pattern and the second fin active region pattern;
• a first source/drain region in contact with the first fin active region pattern, the first source/drain region including a first lower side unit and a first upper side unit on the first lower side unit;
• and
• a second source/drain region in contact with a top surface of the second fin active region pattern, the second source/drain region including a second lower side unit and a second upper side unit on the second lower side unit,
• wherein each of the first lower side unit and the second lower side unit has a constant lateral width or a lateral width reducing away from the substrate in a vertical direction, and the lateral width of the first lower side unit is greater than the lateral width of the second lower side unit.

A semiconductor device comprising:

• a substrate having a first fin active region pattern and a second fin active region pattern formed in a first region and a second region, respectively, wherein the first fin active region pattern and the second fin active region pattern are doped with impurities of different conductivity types;
• a device isolation layer pattern covering side surfaces of lower portions of the first fin active region pattern and the second fin active region pattern, respectively;
• a spacer pattern covering a side surface of a portion of the first fin active region pattern protruding from a top surface of the device isolation layer pattern and a side surface of a portion of the second fin active region pattern;
• a first source/drain region including a first lower side unit in contact with a top surface of the first fin active region pattern and a top surface of the spacer pattern and a first upper side unit on the first lower side unit;
• and
• a second source/drain region including a second lower side unit in contact with a top surface of the second fin active region pattern and the top surface of the spacer pattern and a second upper side unit on the second lower side unit,
• wherein each of the first lower side unit and the second lower side unit has a lateral width reducing away from the substrate in a vertical direction.