The present disclosure provides a semiconductor structure having a semiconductor layer; a gate with a conductive portion and a sidewall spacer; an interlayer dielectric (ILD) surrounding the sidewall spacer; and a nitrogen-containing protection layer, positioning at least on the top surface of the conductive portion of the gate. A top surface of the conductive portion and a top surface of the sidewall spacer are substantially coplanar. The nitrogen-containing protection layer is not covering the sidewall surface of the sidewall spacer. The present disclosure provides a method for manufacturing a semiconductor structure. The method includes forming a metal gate structure having a conductive portion and a sidewall spacer surrounded by a first ILD; forming a protection layer over the metal gate structure, and the protection layer is formed to cover at least the conductive portion of the metal gate structure; and forming a second ILD over the metal gate structure.