SK Hynix starts Sampling 96-layer 4D QLC NAND

SK Hynix has started to sample what they call 4D CTF (Charge Trap Flash) QLC (Quad-Level-Cell) NAND, delivering up to 1Tb of storage per chip to facilitate the creation of ultra-high-density storage devices. 

So what is 4D NAND? Well, it isn’t 4D. SK Hynix hasn’t somehow broken past the three dimensions that that universe occupies. No, this is just 3D NAND, but what SK Hynix has done is place their periphery circuits under their 3D NAND stack, reducing their NAND’s die space requirements. 

Think of it this way. Imagine a large residential tower block and a smaller car park beside it. The tower block is 3D NAND, and the car park is the Periphery, control circuits that sit at the edge of NAND chips. SK Hynix’s design builds the tower black/NAND on top of the car park, allowing the whole structure to take up less die area. SK Hynix calls this 4D, but it’s just a fancier, more efficient implementation of 3D NAND.  

SK Hynix’s new NAND is now being sampled to SSD controller manufacturers, such as Silicon Motion, who will enable support for this new NAND type on their future SSD control circuits. Wallace Kou, the Chief Executive Officer of Silicon Motion, has confirmed that the company has received QLC samples from SK Hynix and that these samples “meet client SSD product requirements”, noting that they are “impressed by its overall performance.” 

SK Hynix also plans to produce enterprise-grade QLC SSD algorithms and controllers internally, with hopes to release SSD solutions that will be able to compete with high-capacity HDDs within the datacentre market. 

Moving forward, SK Hynix plans to stack their 4D NAND higher to create 128-stack NAND with their 6th generation 3D NAND technology. Further in the future, over 500 NAND layers are expected, though SK Hynix has not set a timeframe for their NAND stacking target.