A method for producing a 3D memory device, the method including: providing a first level including a first single crystal layer; forming first alignment marks and control circuits in and on the first level, where the control circuits include first single crystal transistors, where the control circuits include at least two metal layers; forming at least one second level disposed on top of the first level; performing a first etch step within the second level; forming at least one third level disposed on top of the at least one second level; performing a second etch step within the third level; and performing additional processing steps to form a plurality of first memory cells within the second level and a plurality of second memory cells within the third level, where the first memory cells include second transistors, and where the second memory cells include third transistors.