Memory devices are already fully 3D. DRAM has been using stacked capacitors for more than 10 years, where the logic is on the wafer surface but the storage cap

Memory devices are already fully 3D. DRAM has been using stacked capacitors for more than 10 years, where the logic is on the wafer surface but the storage capacitors are built up onto the fully processed wafer. 3D NAND (VNAND) is also fully vertical -- again, the logic is all on the wafer surface but the storage cells are built up.