A through-silicon via structure is formed by providing a substrate having a first conductive catch pad and a second conductive catch pad formed thereon. The substrate is secured to a wafer carrier. A first etch of a first type is performed on the substrate underlying each of the first and second conductive catch pads to form a first partial through-substrate via of a first diameter underlying the first conductive catch pad and a second partial through-substrate via underlying the second conductive catch pad of a second diameter that differs from the first diameter. A second etch of a second type that differs from the first type is performed to continue etching the first partial through-substrate to form equal depth first and second through-substrate vias respectively to the first and second conductive catch pads.