A method for producing a 3D semiconductor device including: providing a first level including a first single crystal layer; forming a first metal layer on top of first level; forming a second metal layer on top of the first metal layer; forming at least one second level above the second metal layer; performing a first lithography step on the second level; forming a third level on top of the second level; performing a second lithography step on the third level; perform processing steps to form first memory cells within the second level and second memory cells within the third level, where first memory cells include at least one second transistor, and the second memory cells include at least one third transistor; and deposit a gate electrode for the second and the third transistors simultaneously.