SK hynix Starts Mass Production of 321-Layer 4D NAND Flash with 1Tb Capacity

SK hynix Inc. started mass production of a world’s 1st TLC ^(*) – based 321-high 4D NAND flash with 1Tb capacity.

Following its previous record as the industry’s 1st provider of the world’s highest 238-layer NAND since June last year, it has become the world’s 1st supplier of the NAND with more than 300 layers by finding a technological breakthrough for stacking. The company plans to provide the 321-high products to customers from the 1H25.

Stacking more than 300 layers came into reality as the company successfully adopted the ‘3 plugs’ ^(**) process technology. Known for an excellent production efficiency, the process electrically connects 3 plugs through an optimized follow-up process after 3 times of plug processes are finished. For the process, the company developed a low-stress ^(***) material, while introducing the technology that automatically corrects alignments among the plugs.

With the adoption of the same development platform from the 238-high NAND on the 321-high product, the company could also improve the productivity by 59%, compared with the previous-gen, by minimizing any impacts from a process switch.

The latest product comes with an improvement of 12% in data transfer speed and 13% in reading performance, compared with the previous-gen. It also enhances data reading power efficiency by more than 10%.

SK hynix plans to steadily expand the use of the 321-high products by providing them to the nascent AI applications, which require low power and high performance.

Jungdal Choi, head, NAND development, SK hynix, said that the latest development brings the company a step closer to the leadership of the AI storage market represented by SSD for AI data centers and on-device AI. “SK hynix is on track to advancing to the Full Stack AI Memory Provider by adding a perfect portfolio in the ultra-high performance NAND space on top of the DRAM business led by HBM.”

^(*) NAND flash products are categorized into single-, multi-, triple-, quadruple-, and penta-level cells, depending on the number of the information in the format of bit unit is stored in a cell. A bigger number of information stored means more data can be stored in the same space.
^(**) Plug: a vertical hole through layers of substrates aimed at creating cells at once
^(***) Low Stress: Preventing wafer warpage by changing the material into the plugs