Techniques and mechanisms for providing electrical insulation of a through-substrate interconnect (TI). In an embodiment, the TI extends between a first side of the substrate and a second side of the substrate opposite the first side. The substrate has formed therein a conductive shell structure that extends at least partially around a periphery of the TI. A first dielectric liner structure is disposed between the conductive shell structure and a bulk material of the substrate. A second dielectric liner structure is disposed between the conductive shell structure and the TI. In another embodiment, a voltage of the conductive shell structure is allowed to float while the TI exchanges a signal or a supply voltage.