DESIGN APPLICATIONS OF BURIED POWER RAILS

A semiconductor device includes a substrate, one or more transistors, a metal layer, one or more buried power rails, and at least one wall-via structure. The transistors and the metal layer are manufactured above a top surface of the substrate. The buried power rails are in one or more corresponding trenches in the substrate below the top surface of the substrate. At least one wall-via structure extends between the first buried power rail and the metal layer and electrically connects the first buried power rail to the metal layer. The wall-via structure includes a plurality of intermediate metal layers sandwiched between the first buried power rail and the metal layer. Alternatively, the wall-via structure includes a length that is greater than or equal to four times a basic length unit for components in layers between the first buried power rail and the metal layer for the semiconductor device.