Approaches for formation of a circuit via which electrically connects a first thin film metallization layer a second thin film metallization layer are described. Via formation involves the use of an anodization barrier and/or supplemental pad disposed in a via connection region prior to anodization of the first metallization layer. The material used to form the barrier is substantially impermeable to the anodization solution during anodization, and disrupts the formation of oxide between the electrically conducting layer and the barrier. The supplemental pad is non-anodizable, and is covered by the barrier to substantially prevent current flow through the pad during anodization. Following anodization, the barrier is removed. If the supplemental pad is sufficiently conductive, it can be left on the first metallization layer after removal of the barrier. The second metallization layer is disposed over the anodized layer, making electrical contact with the first electrically conductive layer in the via connection region.