Engineering titans Kioxia (the Japanese partner) and the American SanDisk (part of Western Digital) are about to present at the International Solid-State Circuits Conference (ISSCC) a new 3D QLC NAND chip that achieves a mind-blowing density, setting a new industry benchmark.
This new chip is expected to offer a density of 37.6 Gbit/mm², which translates to nearly 4.7 GB per square millimeter. This is a colossal achievement, which in practice means that the area of a matchstick will be able to store terabytes of information. The engineers will present a paper titled “Two-Terabit 3D Flash Memory with Four Bits Per Cell, Six-Plane Architecture, 37.6 Gbit/mm2 Density and Over 85 MB/s Write Speed,” which reveals the key parameters of the technology.
This is the tenth generation of BiCS (BiCS10), using four bits per cell (QLC) and an impressive 332-layer design. In comparison, the TLC (three bits per cell) variant of BiCS10 achieves a calculated density one-third lower – about 29.1 Gbit/mm2. While the new QLC chip, like its predecessor, offers a capacity of 2 terabits (256 GB) per die, the significantly higher density could allow for the creation of chips with capacities reaching 8 TB. At this density and capacity, the area of the die itself can be calculated at a modest 55 mm².
In addition to the sheer density, the new chip also promises a serious leap in speed. The BiCS10 TLC version will feature a 4.8 Gbps interface, which is a significant improvement over the 3.6 Gbps of BiCS8. Although QLC is always a bit slower than TLC, the six-layer architecture of BiCS10 QLC will provide write speeds of over 85 MB/s, which positions it ahead of the competition, such as the 75 MB/s of SK hynix's V9 QLC.
By reaching 332 layers, Kioxia and SanDisk enter direct competition with Samsung's future plans, which promise to reach 400 layers with their V10. In this technological race, every layer, every bit and every square millimeter matters. The current victory of Kioxia and SanDisk is a sure sign that we will soon see SSDs with unprecedented capacities that will make current terabyte solutions look like a relic of the past.