US Patent 10515935 3D semiconductor device and structure

A 3D semiconductor device, the device including: a first single crystal layer; at least one first metal layer above the first single crystal layer; a second metal layer above the first metal layer; a plurality of first transistors atop the second metal layer; a plurality of second transistors atop the second transistors; a plurality of third transistors atop the second transistors; a third metal layer above the plurality of third transistors: a fourth metal layer above the third metal layer; and a second single crystal layer above the fourth metal layer; and a plurality of connecting metal paths from the fourth metal layer to the second metal layer, where at least one of the plurality of third transistors is aligned to at least one of the plurality of first transistors with less than 40 nm alignment error, where the fourth metal layer is providing global power distribution to the device.