1. A method of making a semiconductor device, comprising: providing a carrier for supporting the semiconductor device; mounting a first semiconductor die to the carrier, the first semiconductor die having a contact pad; mounting a first dummy die to the carrier, the first dummy die having a through-silicon via (TSV); encapsulating the first semiconductor die and the first dummy die using a wafer molding material; forming a first interconnect structure over the first semiconductor die and the first dummy die, the first interconnect structure being connected to the contact pad of the first semiconductor die and the TSV of the first dummy die; removing the carrier; forming a second interconnect structure over the first semiconductor die and the first dummy die, the second interconnect structure being connected to the TSV of the first dummy die; and connecting a semiconductor package to the second interconnect structure.