SK Hynix, a latecomer in the NAND memory area, has been faster thann rivals Toshiba and Micron in the inotruduction of 3D NAND mass-production.
Instead of narrowing the linewidth of memory's internal circuits, NAND makers have attempted to improve performance and speed by building circuits in layers. This is where the 3D and memory emerges.
Samsung Electronics is the leader in the fiels. The company developed a 24-stack model in late 2013 and launched the 48-stack one from August 2015.
Toshiba, the inventor of NAND memory, and Micron, have both so far failed to establish a NAND mass-production system.