A method of forming void-free, high aspect ratio through-substrate vias by “bottom-up” electroplating. In one embodiment, the method requires providing a substrate, forming a dielectric layer on the substrate's bottom side, providing at least one perforation through the dielectric layer, forming a via hole through the substrate from its top side to the dielectric layer and over the perforations, forming an isolation layer on the sidewalls of the via hole, forming a metal seed layer on the bottom side of the dielectric layer, electroplating the seed layer such that all of the perforations are plugged, and electroplating up the via hole from the plugs to fill the via hole.