Samsung has just announced a QLC version of the 3D NAND that the company has calls its 9th-generation V-NAND. This follows the April announcement that its TLC version of the 280-layer 9th-generation device was in volume production.
Naming the product a “Memory Solution for AI Era”, Samsung tells us that the 280-layer part has: “the highest layer count in the industry with a double stack structure.” At first glance, this seems to tell us that the 280-layer part has the industry’s highest layer count, but what the company really seems to be saying is that it reaches 280 layers with only two decks, which is an impressive feat. (Today SK hynix has the highest layer count with 321 layers, which TechInsights has determined has three decks. It’s worth mentioning that the Samsung part has been in production since April as a TLC part, while SK hynix is only sampling.)
A deck’s layer count is limited by the aspect ratio of the holes etched through the 3D NAND stack. If your hole diameter is limited to 40nm, and if you can’t make a uniform hole with more than a 60:1 aspect ratio, then the only way you can increase layer count is to make thinner layers.
Samsung has always excelled at thinning the layers of its 3D NAND, and the fact that it can make a single deck with 140 layers is amazing. (The SK hynix part has 107-layer decks, and that’s amazing too, but it’s a lot lower number.) Samsung does this through something it calls Designed Mold, which is a technique Samsung developed to assure that extremely thin layers are uniform. They tell us that this approach not only enabled the high layer count, but that it: “has improved data retention performance by roughly 20% compared to previous versions, leading to enhanced product reliability.”
Even so, that high aspect ratio (and I’m only guessing that it’s 60:1) is also a difficult challenge. Samsung tells us that its Channel Hole Etching technology allowed the company to achieve that “highest layer count in the industry with a double stack structure.” They also point out that the part has an 86% higher density than the company’s previous generation QLC V-NAND.
This is an interesting enhancement on Samsung’s 280-layer TLC part, and it should help bring QLC into an increasing number of applications. We look forward to the next few years as Samsung continues its march toward producing a 3D NAND with more than 1,000 layers by 2030.