An IC structure includes a source epitaxial structure, a drain epitaxial structure, a first silicide region, a second silicide region, a source contact, a backside via rail, a drain contact, and a front-side interconnection structure. The first silicide region is on a front-side surface, a first sidewall of the source epitaxial structure, and a second sidewall of the source epitaxial structure. The second silicide region is on a front-side surface of the drain epitaxial structure. The source contact is in contact with the first silicide region and has a protrusion extending past a backside surface of the source epitaxial structure. The backside via rail is in contact with the protrusion of the source contact. The drain contact is in contact with the second silicide region. The front-side interconnection structure is on a front-side surface of the source contact and a front-side surface of the drain contact.