A semiconductor structure includes a first dielectric layer over a metal line and a redistribution layer (RDL) over the first dielectric layer. The RDL is electrically connected to the metal line. The RDL has a curved top surface and a footing feature, where the footing feature extends laterally from a side surface of the RDL. A second dielectric layer is disposed over the RDL, where the second dielectric layer also has a curved top surface.