A semiconductor device comprising: a first single crystal silicon layer comprising first transistors, first alignment marks, and at least one metal layer overlying the first single crystal silicon layer, wherein the at least one metal layer comprises copper or aluminum more than other materials; and a second single crystal silicon layer overlying the at least one metal layers; wherein the second single crystal silicon layer comprises a plurality of second transistors arranged in substantially parallel bands wherein each of a plurality of the bands comprises a portion of the second transistors along an axis in a repeating pattern.