A wafer level chip scale package (WLCSP) includes a semiconductor device including an active surface having a contact pad, and side surfaces. A mold covers the side surfaces of the semiconductor device. A RDL structure includes a first PPI line electrically connected to the contact pad and extending on the active surface of the semiconductor device. A UBM layer is formed over and electrically connected to the first PPI line. A seal ring structure extends around the upper periphery of the semiconductor device on the mold. The seal ring structure includes a seal layer extending on the same level as at least one of the first PPI line and the UBM layer. A method of manufacturing a WLCSP includes forming a re-routing laminated structure by simultaneously forming an interconnection line and a seal layer on the molded semiconductor devices.