A semiconductor device and a semiconductor package, the device including a pad interconnection structure that penetrates a first buffer dielectric layer and a second buffer dielectric layer, wherein the pad interconnection structure includes copper and tin, the pad interconnection structure includes a central part, a first intermediate part surrounding the central part; a second intermediate part surrounding the first intermediate part, and an outer part surrounding the second intermediate part, a grain size of the outer part is less than a grain size of the second intermediate part, the grain size of the second intermediate part is less than a grain size of the first intermediate part, and the grain size of the first intermediate part is less than a grain size of the central part.