A semiconductor device comprises a first gate electrode on a substrate, a first conductive contact on the first gate electrode, an etch stop layer (ESL) on the first conductive contact, and a second conductive contact extending through the ESL. The first conductive contact has a first width. The second conductive contact has a second width, the second width being smaller than the first width. The ESL overhangs a portion of the second conductive contact. A convex bottom surface of the second conductive contact physically contacts a concave top surface of the first conductive contact.