US Patent 9871034 Semiconductor device and structure

An Integrated Circuit device, including: a base wafer including single crystal, the base wafer including a plurality of first transistors; at least one metal layer providing interconnection between the plurality of first transistors; and a second layer of less than 2 micron thickness, the second layer including a plurality of second single crystal transistors, and the second layer overlying the at least one metal layer; wherein the material composition of at least one of the plurality of second single crystal transistors is substantially different than the material composition of at least one of the plurality of first transistors.