South Korea's No. 2 chipmaker SK hynix Inc. said Monday it has developed the first 72-layer 256Gb 3d NAND flash, which will be mass-produced in the second half of this year.

The new chip 72-Layer 3D NAND uses 1.5 times more cells than the company's 48-Layer 3D, which is already in mass production. A single 256Gb NAND Flash chip can represent 32GB storage. It achieves approximately 30 percent more manufacturing productivity over its predecessor 48-Layer. Also by bringing high-speed circuit design into the new chip, its internal operation speed is two times faster and read/write performance is 20 percent higher than a 48-Layer 3D NAND chip.

However, competitors have a smaller cell size than SK Hynix, which makes their 3D NAND production more difficult.

Stacking 72 layers in a flash chip is an industry-firts for SK hynix, but the 256Gb capacity is not. Toshiba's 64-layer flash die has a 512Gb capacity and it is a TLC (3bits/cell) device like the new SK Hynix chip.

Toshiba's foundry partner Western Digital also started early production runs of a 512Gb, 64-layer die in February.

Samsung has also a 512Gb, 64-layer flash chip.

SK Hynix launched 36-Layer 128Gb 3D NAND chips in April 2016, and has been mass producing 48-Layer 256Gb 3D NAND chips since November 2016.

3D NAND demand will rapidly increase across AI (Artificial Intelligence), big data and cloud storage in the 4th industrial revolution. According to Gartner, NAND Flash market revenue is expected to total USD 46.5 billion in this year and post continuous growth to amount to USD 56.5 billion in 2021.