A method of forming an interposer includes providing a semiconductor substrate, the semiconductor substrate having a front surface and a back surface opposite the front surface; forming one or more through-silicon vias (TSVs) extending from the front surface into the semiconductor substrate; forming an inter-layer dielectric (ILD) layer overlying the front surface of the semiconductor substrate and the one or more TSVs; and forming an interconnect structure in the ILD layer, the interconnect structure electrically connecting the one or more TSVs to the semiconductor substrate.