An interconnection structure includes a first interlayer dielectric layer, a first conductive line, a protection layer, a second interlayer dielectric layer, and a connection plug. The first conductive line is partially disposed in the first interlayer dielectric layer. The protection layer is disposed on the first conductive line and the first interlayer dielectric layer. The protection layer covers a top surface and a sidewall of the first conductive line. The protection layer includes a recess disposed corresponding to the first conductive line in a vertical direction. The second interlayer dielectric layer is disposed on the protection layer. The connection plug penetrates at least a part of the second interlayer dielectric layer and the protection layer for being connected with the first conductive line.