A 3D IC device including: a first semiconductor layer including first mono-crystallized transistors, where the first mono-crystallized transistors are interconnected by at least one metal layer including aluminum or copper; a second layer including second mono-crystallized transistors and overlaying the at least one metal layer, where the at least one metal layer is in-between the first semiconductor layer and the second layer; a global power grid to distribute power to the device overlaying the second layer; and a local power grid to distribute power to the first mono-crystallized transistors, where the global power grid is connected to the local power grid by a plurality of through second layer vias, and where the vias have a radius of less than 150 nm.