A device includes an interposer, which includes a substrate; and at least one dielectric layer over the substrate. A plurality of through-substrate vias (TSVs) penetrate through the substrate. A first metal bump is in the at least one dielectric layer and electrically coupled to the plurality of TSVs. A second metal bump is over the at least one dielectric layer. A die is embedded in the at least one dielectric layer and bonded to the first metal bump.