A NAND is a non-volatile flash memory type. Flash memory is used for storing and transmitting data between devices, usually a PC and other digital devices: this is what makes our USB “flash drives” and our external HDDs work, as well as making hybrid hard drives more robust.
What is 3D NAND? Named after the ‘not-AND’ logic gates of digital electronics, 3D NAND – sometimes known interchangeably as vertical or V-NAND – is the next ‘new’ thing you’d be remiss not to know about.
What Is 3D NAND? (And Why Not 2D NAND?)
The 3D NAND, specifically, stacks the memory/silicon chips/cells vertically on top of each other in multiple layers. (Hence why it’s called the V NAND, although a specific 3D NAND vs. V NAND discussion will follow).
Before this, the NAND was a planar 2D NAND, with the chips simply arranged next to each other in a matrix, two-dimensionally. Even before that was when both types of flash memory co-existed in harmony in the market, the NOR and NAND (not-OR and not-AND, respectively), both built with FGTs.
The 80s ultimately gave way to NAND as they emerged as the market leader of flash memory cells, with the traditional 2D NAND serving the world well up until recent years when its architecture simply reached its natural limit with how much data it could physically store.
What Is 3D NAND’s Major Selling Point?
Enter the 3D NAND, where the vertically stacked layers provide more density and capacity for storage in the same “area”, also driving down the cost per gigabyte, reducing the amount of power consumed, and boosting data write performance, reliability, and efficiency.
In terms of data density, the 3D NAND’s very architecture allows it to pack more storage into the same “footprint” – memory chip area – as compared to a 2D NAND. Not only that, but this means that denser higher-capacity devices, such as SSDs, can be built from denser chips.
This also greatly impacts the cost-per-byte factor in a vastly positive way, with a nearly 1-to-10 ratio in terms of greater storage, meaning that, even with a greater price tag, the 3D NAND ends up much cheaper than the 2D NAND, allowing for even greater and more cost-effect storage application solutions. The best SSDs for gaming utilize the 3D NAND.
What’s more is that the structure of a 2D NAND makes it such that the distance that bits travel between cells is finite, meaning higher latency when the storage capacity needs to be increased, which counter-intuitively lowers the performance capabilities as the 2D NAND devices get larger.
A 3D NAND flash device, of course, gets around this problem by the memory cells being stacked and interconnected, meaning the storage capacity remains high and so does the performance, owing to lower latency.
This also means that the flash memory in question can use up to as little as half the power of a 2D NAND since it can be written in a single pass.
V NAND Vs. 3D NAND: Is There A Difference?
The way we’ve been explaining things, you’d been forgiven for thinking, as most people commonly do, that the V NAND is the absolute same thing as a 3D NAND.
The difference is in propriety. Samsung lays claim to the V NAND name, with the difference usually being in the fact that their stacks are even more stacked than before, such as 48 layers where there were once 32 meaning, of course, more capacity once again.
This is where a discussion of MLC, TLC, and QLC technologies. These stand for multiple-level cells, triple-level cells, and quad-level cells, respectively, referring to the number of bits held in each NAND memory cell.
The process of manufacturing a 3D NAND flash device is very complex and calculated, with a raw wafer being taken through to a completed chip in thousands of steps and processes. Part of the strict manufacturing control and purity with regards to the material dies and cells also lies in choosing the right designs.
Instead of having to choose 3D NAND vs. TLC-backed cells or a cheap 3D NAND vs. MLC being employed elsewhere, the fact that a 3D NAND can employ both MLC and TLC cells is good news, with these devices having the capability to be rewritten an average of 1500 to 3000 times.