Aspects of the present disclosure provide a method for fabricating a semiconductor structure. For example, the method can include forming a stack of metal structures on a substrate, the stack of metal structures including multiple metal structures that are vertically stacked over and electrically separated from one another, each of the metal structures including a ring and one or more pad contacts extending from the ring, the rings of the metal structures being vertically aligned with one another. The method can also include forming one or more channel structures within the rings of the metal structures, the channel structures being electrically separated from one another and electrically separated from the substrate. The method can also include forming one or more interconnections that extend from a position above the stack of metal structures to corresponding one or more of the pad contacts of the metal structures.