A semiconductor structure is provided. The semiconductor structure includes a gate structure over a fin structure. The semiconductor structure also includes a source/drain structure in the fin structure and adjacent to the gate structure. The semiconductor structure also includes a first contact plug over the source/drain structure. The semiconductor structure also includes a first via plug over the first contact plug. The semiconductor structure also includes a dielectric layer surrounding the first via plug. The first via plug includes a first group IV element and the dielectric layer includes the first group IV element and a second group IV element.