Methods for forming semiconductor structures are provided. The method includes forming a gate structure over a substrate and forming a source/drain structure adjacent to the gate structure. The method further includes forming a mask structure over the gate structure and forming a contact over the source/drain structure. The method further includes selectively forming a metal-containing layer over a top surface of the contact and forming a dielectric layer over the substrate and covering the gate structure and the contact. The method further includes forming a trench through the dielectric layer and the metal-containing layer to expose the top surface of the contact and forming a conductive structure in the trench.