A 3D semiconductor device, the device including: a first level including a plurality of first single crystal transistors, contacts, and a first metal layer, where a portion of the first single crystal transistors are interconnected, where the interconnected includes the first metal layer and the contacts, and where the portion of the first single crystal transistors are interconnected forms memory control circuits; a second level overlaying the first level, the second level including a plurality of second transistors; a third level overlaying the second level, the third level including a plurality of third transistors; a fourth level overlaying the third level, the fourth level including a plurality of fourth transistors; and a second metal layer overlaying the fourth level, where the plurality of second transistors are aligned to the plurality of first transistors with a less than 40 nm alignment error.