Through-Silicon-Via (TSV) structures can be provided by forming a conductive via through a substrate extending from an upper surface of the substrate to a backside surface of the substrate, that is opposite the upper surface, and having a conductive protective layer comprising Ni and/or Co formed at a bottom of the conductive via. A polymer insulating layer can be formed on the backside surface that is separate from the substrate and in contact with the conductive protective layer.