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Tosh doubles 64-layer 3D flash chip capacity with a bit of TLC

1TB chip incoming

Toshiba has introduced its first 64-layer 3D NAND device that doubles the capacity of its 256Gb product to 512Gb using a TLC (3bits/cell) design.

That means a die holds 64GB. Sample shipping started this month and mass production is slated for the second half of the year. Both enterprise and consumer SSD products are expected. Toshiba says the 512Gb die has a 65 per cent larger capacity per unit chip size than its 48-layer, 256-gigabit (32GB) device, and has increased memory capacity per silicon wafer, reducing the cost per bit.

Flash JV Partner WD has already spoken about its 512Gb die.

Toshiba is looking forward to another NAND roadmap event, a 1TB product with a 16-die stacked architecture in a single package. That would mean each die having a capacity of 64GB, and therefore the product would use the 512Gb chip product above. Sample shipping of the 1TB chip will start in April.

Analyst Jim Handy has produced a table comparing Toshiba/WD, Samsung and Micron 64-layer 3D NAND devices.

Feature Micron Toshiba/WD Samsung
Density 768Gb 512Gb 512Gb
Die Size 179mm2 132mm2 129mm2
Gb/mm2 4.29 3.88 3.97
Layers (64) 64 64
Bits/Cell 3 3 3
String Stacking? Yes (Yes?) No
Cell Type Floating Gate Charge Trap Charge Trap

He points out: "All three use 64 layers and 3bits/cell effectively, yet Micron's Gb/mm² is higher than either of the others thanks to the fact that Micron manufactures the chip's CMOS logic circuits underneath the memory array, while its competitors put the logic alongside the array.

"None of this really matters, though, until all three companies bring these products to mass production. It's unclear at this point when that will actually occur."

We now have Toshiba saying it will mass produce its 512Gb 64-layer product in the second half of 2017 with enterprise and consumer SSDs on the roadmap.

It has 7.68TB ZD6300 NVMe PCIe flash drives in its product list, using 2D Planar eMLC NAND with 128Gbit components. A straight 512Gb die for 128Gb die substitution, if it were possible, would produce a 30.7TB SSD. The capacity prospect is mouth-watering, isn't it?

And this positive technology news makes a welcome change from reading about Toshiba's financial woes. ®

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