Kioxia Demos HLC 3D NAND and Talks About OLC NAND



The best SSDs currently use TLC or maybe QLC memory. Kioxia (formerly Toshiba Memory) was the first 3D NAND maker to start talking about 5-bits-per-cell (5 bpc) PLC (penta level cell) 3D NAND memory back in 2019. Kioxia’s scientists and engineers certainly don’t want to rest on their laurels, and this year they demonstrated operation of 6 bpc — hexa level cell, or HLC — 3D NAND memory and believe that even 8 bpc — octa level cell, or OLD — 3D NAND is possible. But there are some important nuances. 

To store more than one bit per cell, NAND memory has to hold multiple distinct voltage levels in that cell. For example, MLC has four states per cell, TLC uses eight voltage levels, QLC has 16 voltage levels, and PLC has 32 voltage states. In other words, two taken to the power of whatever cell level you’re talking about. To store six bits per cell (HLC), that cell has to hold 2^6, or 64 voltage levels.



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