THREE-DIMENSIONAL MEMORY DEVICES, SYSTEMS, AND METHODS FOR FORMING THE SAME

A three-dimensional 3D memory device includes a substrate, a peripheral device disposed on the substrate, a memory stack disposed above the peripheral device and including a plurality of conductor/dielectric layer pairs, and a plurality of memory strings, each of the memory strings extending through the memory stack. The peripheral device includes at least a transistor disposed on the substrate. The transistor includes a gate stack. The gate stack of the transistor includes a staircase structure, and an operational voltage of the transistor is above 5 volts.