SK Hynix Begins Mass Production of 321-Layer NAND Flash

On November 21, SK Hynix announced the commencement of mass production for its groundbreaking 321-layer 1Tb (terabit) TLC (Triple-Level Cell)* 4D NAND flash memory, setting a new industry benchmark.

*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.

According to SK Hynix, the company successfully launched its previous-generation 238-layer NAND flash memory in June 2023 and has now pushed the boundaries of technology by introducing the 321-layer product. This new product is expected to be available to customers starting from the first half of next year, aiming to meet growing market demands.

The development of the 321-layer NAND flash memory involved the adoption of the efficient "3-Plug*" process. This method divides the through-hole process into three stages, optimizing subsequent steps to achieve electrical connectivity between the holes. Innovations such as low-stress* materials and alignment correction technology for through-holes were instrumental in overcoming stacking challenges. Leveraging the development platform from the 238-layer NAND flash, the company minimized process variations, achieving a 59% improvement in production efficiency over the previous generation.

*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

Compared to its predecessor, the 321-layer product offers a 12% increase in data transfer speed, a 13% boost in read performance, and over a 10% improvement in energy efficiency during data reading. These advancements position the 321-layer NAND flash memory as a key enabler for emerging AI-driven markets requiring low-power, high-performance solutions.

SK Hynix plans to expand the application range of its 321-layer NAND flash memory, particularly in AI data centers, edge AI, and other advanced storage markets. The company's Vice President of NAND Flash Development, Choi Jung-dal, emphasized, “By leading the mass production of NAND flash exceeding 300 layers, SK Hynix has secured a competitive edge in AI-centric storage markets, including SSDs for data centers and edge AI devices. Alongside our high-performance DRAM, represented by HBM, we now offer a comprehensive portfolio of memory solutions optimized for AI applications, reinforcing our position as a leader in the field.”