Kioxia and Western Digital build 162-layer 3D NAND

Kioxia and Western Digital have announced the sixth generation of their BiCS 3D NAND technology, with 162-layers and a 40 per cent smaller die than their gen 5 BiCS 112-layer technology.

Each new BiCS (Bit Cost Scaling) generation should have a lower cost per bit than its predecessor. The two suppliers did not disclose how much this is reduced in Gen 6, but they revealed that manufactured bits per wafer are increased by 70 per cent over gen 5.

Siva Sivatram

Dr. Siva Sivaram, Western Digital’s President of Technology & Strategy, cited performance, reliability and cost benefits for Gen 6. He said the new generation introduces “innovations in vertical as well as lateral scaling to achieve greater capacity in a smaller die with fewer layers”.

We think product will announced and available by the first 2022 quarter – but note the companies did not say what capacity dies could be built using gen 6 BiCS NAND or when SSDs using the technology might appear.

Gen 6 BiCS NAND improves various parameters compared to gen 5:

  • Up to 10 per cent greater lateral cell array density
  • Nearly 2.4x program performance improvement through 4-plane operation
  • 10 per cent lower read latency
  • 66 per cent IO speed increase

The 162-layer count represents a 44 per cent increase on gen 5, which is a larger increase than in previous BICS generations. The companies are not saying if the die is built by string stacking, where two 81-layer components one above the other.

Three NAND suppliers have developed 3D NAND with greater layer counts than Kioxia and Western Digital. Micron, SK hynix and Samsung have each achieved 176, leaving Intel at the 144-layer level and YMTC trailing with 128. Intel’s future development is moving into the hands of SK hynix, as that company is buying Intel’s NAND operation.

SK hynix revealed a roadmap to 500+ and even 800+ layers in August 2019. Other suppliers are understood to have similar internal roadmaps. Kioxia and Western Digital announced the 112-layer BiCS in January 2020. Based on the industry trend to add more layers and on Kioxia and Western Digital’s actual layer count increases, we could anticipate a potential BiCS 7 announcement with 250+layers in 2022.

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