Friday, December 30, 2016

QLC or 96L 3D NAND... which is better

As we look into the future, one question is:
"What is the best way to scale costs in 3D NAND?"... more layers or more bits per cell?

The assumption is that we will keep adding layers, use string stacking as needed. We also will go to QLC or 4Bits per cell. We will do both. In reality companies have to decide where to focus efforts and jumping to increased layers and QLC at the same time might be difficult to engineer and market.

String stacking adds wafer cost and die size. QLC could control both but will limit write and potentially read performance even lower than TLC. Going from 64L to 96 adds theoretical 50% more bits. Going from TLC to QLC adds theoretical 33% more bits.

Cost estimates based on a 768Gb die in 2018 production are available with scenarios favoring one or the other based on yields and die size estimates. Details are available with all the numbers and yields and cost.... but most scenarios show that QLC will need design changes to prevent reduced performance to stay competitive.

MKW Ventures Consulting, LLC

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