A semiconductor structure includes a substrate, a pair of first fins extending from the substrate, a pair of second fins extending from the substrate, an isolation feature over the substrate and separating bottom portions of the first and the second fins, a pair of first epitaxial semiconductor features over the pair of first fins respectively, a pair of second epitaxial semiconductor features over the pair of second fins respectively, and a first dielectric feature sandwiched between and separating the pair of first epitaxial semiconductor features. The pair of second epitaxial semiconductor features merge with each other.