A semiconductor device may include a substrate including a first active region including first active patterns spaced apart by a first interval, a second active region including second active patterns spaced apart by a second interval, first and second source/drain regions on the first and second active regions, first and second contact structures connected to the first and second source/drain regions, first and second conductive through-structures connected to the first and second contact structures, a power delivery structure in contact with bottom surfaces of the first and second conductive through-structures, a frontside interconnection structure, and a backside interconnection structure. The first conductive through-structure may be connected to the first source/drain region through the first contact structure. The second conductive through-structure may be connected to the second source/drain region through the frontside interconnection structure. The second interval may be different than the first interval.