Western Digital BiCS3 Flash Goes QLC - 96GB per die!

Subject: Storage | August 2, 2017 - 06:21 PM |
Tagged: western digital, wdc, WD, tlc, slc, QLC, nand, mlc, flash, 96GB, 768Gb, 3d

A month ago, WD and Toshiba each put out releases related to their BiCS 3D Flash memory. WD announced 96 layers (BiCS4) as their next capacity node, while Toshiba announced them reliably storing four bits per cell (QLC).


WD recently did their own press release related to QLC, partially mirroring Toshiba's announcement, but this one had some additional details on capacity per die, as well as stating their associated technology name used for these shifts. TLC was referred to as "X3", and "X4" is the name for their QLC tech as applied to BiCS. The WD release stated that X4 tech, applied to BiCS3, yields 768Gbit (96GB) per die vs. 512Gbit (64GB) per die for X3 (TLC). Bear in mind that while the release (and the math) states this is a 50% increase, moving from TLC to QLC with the same number of cells does only yields a 33% increase, meaning X4 BiCS3 dies need to have additional cells (and footprint) to add that extra 17%.

The release ends by hinting at X4 being applied to BiCS4 in the future, which is definitely exciting. Merging the two recently announced technologies would yield a theoretical 96-layer BiCS4 die, using X4 QLC technology, yielding 1152 Gbit (144GB) per die. A 16 die stack of which would come to 2,304 GB (1.5x the previously stated 1.5TB figure). The 2304 figure might appear incorrect but consider that we are multiplying two 'odd' capacities together (768 Gbit (1.5x512Gbit for TLC) and 96 layers (1.5x64 for X3).

Press blast appears after the break.