Kioxia and SanDisk have begun sampling BiCS10, a tenth generation 3D NAND die that stacks 332 layers and stores 1 terabit of TLC at a bit density above 29 gigabits per square millimetre, a figure Tom's Hardware ranks as the densest any flash maker has yet disclosed.
The layer count is the eye catcher, and it is also the wrong number to watch. Samsung's latest V NAND generation reaches 400 layers, SK hynix sits at 321 and Micron's current node at 276, according to the comparison assembled by Blocks and Files. On that scoreboard Kioxia and SanDisk rank second. On density per square millimetre, the number that actually sets cost per bit, their 332 layers claim the lead over a taller Samsung stack. The marketing number and the economics number have parted company.
Two structural choices did the work. CBA, for CMOS directly Bonded to Array, builds the control logic on its own wafer and bonds it to the memory array, so peripheral circuitry stops stealing die area from cells. On Pitch Select Gate Drain, OPS in the companies' shorthand, prunes unused memory holes and tightens lateral spacing. The density came from the sides, not just the stack.
"We will firmly respond to the market's growth," Kioxia chief executive Hiroo Ota says of AI demand for flash. Translated, the density crown is a capacity decision as much as a technology one: mass production is slated for Fab 2 at Kitakami in 2027, so nothing BiCS10 does will touch supply, pricing or market share until wafers ship in volume. Sampling now starts the long qualification clocks at the hyperscalers.
Performance moves with the density. The Toggle DDR6.0 interface runs to 4.8 gigabits per second, a third faster than BiCS8, while write power improves 18 percent and read power 30 percent, per the companies' figures. A QLC variant is possible on the same die, which would add another third of capacity for enterprise drives where endurance budgets allow.
For buyers of data centre SSDs the practical read is patience. BiCS10 targets Gen6 enterprise drives for AI storage, and if the density claim survives production, cost per bit on those drives could bend downward once volume arrives. That is a 2027 story sampling its way through 2026.
Bootnote: BiCS10 strings together three stacks of roughly 110 layers each, and the arithmetic is the story. BiCS8 stopped at 218 layers, so the new die adds 52 percent more layers yet 59 percent more density. The extra seven points came sideways, from lateral shrink, not from height.
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