US Patent 10354995 Semiconductor memory device and structure

A semiconductor device including: a first layer including a first memory cell, the first memory cell including a first transistor; a second layer including a second memory cell, the second memory cell including a second transistor; a periphery layer including a memory peripherals transistor, the periphery layer is disposed underneath the first layer; a memory including at least the first memory cell and the second memory cell, where the second memory cell overlays the first memory cell, where the first memory cell and the second memory cell have both been processed following a lithography step and accordingly are precisely aligned, and where a peripherals circuit includes the memory peripherals transistor and controls the memory; a first external connections underlying the periphery layer, the first external connections includes connections from the device to a first external device; and a second external connections overlying the second layer, the second external connections includes connections from the device to a second external device.