A semiconductor structure according to the present disclosure includes a circuit region disposed over a substrate and a seal ring region disposed over the substrate and completely surrounding the circuit region. The circuit region includes first fins, second fins, n-type epitaxial structures over the first fins, and p-type epitaxial structures over the second fins. The seal ring region includes fin rings extending completely around the circuit region, epitaxial rings disposed over and extending parallel to the fin rings. All of the epitaxial rings over all of the fin rings in the seal ring region are p-type epitaxial rings.