BACKSIDE POWER DELIVERY AND POWER GRID PATTERN TO SUPPORT 3D DIE STACKING

An apparatus and method for efficiently routing power signals across semiconductor dies. A semiconductor fabrication process (or process) places a first semiconductor die in an integrated circuit and stacks a second semiconductor die vertically adjacent to the first semiconductor die. The process forms multiple backside metal layers vertically adjacent to a backside of a silicon substrate of the second semiconductor die. The process forms a first backside metal layer that includes at least a first power route that forms a rectangle within the first backside metal layer. The process forms a second backside metal layer that includes at least a second power rail that forms an L-shape within the second backside metal layer. The process connects one or more corners of the rectangle of the first power rail to a corresponding corner of a separate power rail of the second backside metal layer that forms an L-shape.