3D NAND is flash memory built by stacking memory cells in hundreds of layers, like floors in a tower, instead of spreading them across one flat surface. More layers mainly lower the cost per GB and raise capacity. How fast an SSD feels depends more on its controller, cache, cell type and interface.
Here is how 3D NAND works, where layer counts stand in 2026 and which specs actually matter when you buy.
What Is 3D NAND?
The older generation planar NAND technology utilized the cells in horizontal orientation on one plane of silicon wafer. The makers were able to reduce the size of the cell until 15 nanometers when the cells were too densely arranged and there were errors due to electron leakage.
This was solved by vertically arranging the cells in a channel formed in the wafer. This improved the capacity of the memory due to vertical expansion of the cells instead of reduction of cell size. The technology name given by Samsung is V-NAND.
How Does 3D NAND Work?
1. Charge Trap vs Floating Gate
Every flash cell stores data as trapped electrons. Most 3D NAND now holds that charge in a thin nitride layer, called a charge trap, wrapped around the vertical channel, as shown by chip equipment makers. A few designs still use the older floating gate, a small conductive pocket that holds the charge. Charge trap cells are easier to stack in very tall towers, while floating gate cells tend to hold data longer when a drive sits unpowered.
2. How Makers Stack Hundreds of Layers
No machine can drill one clean hole through 300 layers at once, so makers build the stack in two or more decks and join them, a method called string stacking. They also move the control circuits under the memory array, or build them on a separate wafer and bond the two together. YMTC calls this Xtacking, and Kioxia calls it CBA, which it uses in its new BiCS10 sampling chips.
3D NAND Layer Counts in 2026
Each maker's newest mass production node, based on company announcements and layer roadmaps:
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Maker
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Newest mass production
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Next step
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SK Hynix
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321 layers
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375 layers, targeted for late 2026
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Samsung
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286 layers (V9)
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400 layer class V10
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Micron
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276 layers (G9)
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Not yet announced
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YMTC
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267 layers
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Over 300 layers in development
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Kioxia and SanDisk
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218 layers (BiCS8)
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332 layer BiCS10 at 4.8 Gb/s, sampling since July 2026
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Samsung reportedly targets 1,000 layers by 2030. For the companies that turn these chips into drives, see our list of top internal SSD manufacturers.
SLC, MLC, TLC and QLC in 3D NAND
Layer count tells you how many cells are stacked. Cell type tells you how many bits each cell holds, and that drives endurance more than anything else. These ranges come from current industrial data.
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Cell type
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Bits per cell
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Typical P/E cycles
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Best for
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SLC
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1
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50,000 to 100,000
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Industrial and automotive systems with heavy writes
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pSLC
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1 (on MLC or TLC cells)
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10,000 to 40,000
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Embedded devices needing near SLC life at lower cost
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MLC
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2
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3,000 to 10,000
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Surveillance, logging, edge gateways
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TLC
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3
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1,000 to 3,000
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Most SSDs, laptops and system drives
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QLC
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4
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150 to 1,000
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Bulk storage, backups, game libraries
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Some older guides claim 3D NAND can't be SLC. It can. Industrial SLC and pSLC parts are built on 3D NAND, and nearly every consumer SSD runs part of its TLC or QLC flash in SLC mode as a fast write cache. Five bit PLC cells are in development but not yet in mainstream drives.
3D NAND vs 3D TLC: What an SSD Spec Sheet Tells You
Many shoppers see "3D NAND" on one drive and "3D TLC" on another and try to pick between them. They aren't alternatives. 3D tells you the cells are stacked, and TLC tells you each cell holds three bits, so a 3D TLC drive is simply 3D NAND with the cell type named.
Planar NAND also came in SLC, MLC and TLC, so the word 3D alone says nothing about speed or lifespan. Watch for spec sheets that list only "3D NAND." A brand using TLC usually says so, while a missing cell type often points to QLC.
Do More Layers Make a Better SSD?
No. More layers mean more bits per chip, resulting in reduced cost per gigabyte and increased capacity. However, a 321 layer SSD will not be faster than 218 just because it is more layered.
There are other factors that make an SSD fast. There is the controller, which controls every operation of writing and reading. Then there is the DRAM cache, also known as host memory buffer in some budget SSDs. SLC cache capacity dictates how long fast write speeds can sustain before speeds degrade and NAND interface speed, now capable of reaching 4.8Gb/s, determines maximum speed.
Pay attention to TBW and refer to independent benchmarks. Check out our NVMe vs SATA SSD guide for more info about the interface.
Which 3D NAND Type Should You Choose?
Match the cell type to how much data you'll write:
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Use case
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Best cell type
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Why
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System or boot drive
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TLC
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Steady speed after the cache fills, good endurance
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Game library, media, backups
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QLC
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Lowest cost per TB for mostly read data
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Dashcams and security cameras
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High endurance TLC or MLC cards
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Constant overwrites wear out standard cards
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Industrial and embedded devices
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SLC, pSLC or MLC
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Long life, wide temperatures, heavy writes
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Data center write heavy workloads
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Enterprise TLC
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High TBW and power loss protection
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For cameras, our guide to high endurance microSD cards explains the difference. Digiera builds SSDs, memory cards and USB drives with a choice of NAND type for OEM buyers, and you can request a quote on Digiera's SSD manufacturing page.
3D NAND vs 2D NAND: Pros and Cons
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Factor
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3D NAND
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2D (planar) NAND
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Capacity per chip
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Up to 1Tb and beyond
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Small, limited by cell size
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Cost per GB
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Low
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High
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Speed and power
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Faster, lower power per bit
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Slower, more power per bit
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Cell size
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Larger, more stable cells
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Tiny cells prone to leakage
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Manufacturing
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Very complex, deep etching and bonding
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Simpler, mature process
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Current use
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Nearly all SSDs, cards and USB drives
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Legacy and niche parts
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The main downside of 3D NAND is how hard it is to make, which is why only a handful of companies can produce it at scale.
FAQs
What is the difference between 3D NAND and TLC?
3D NAND refers to the construction of the flash cells, specifically their stacking in layers. TLC refers to the data stored by each cell, i.e., three bits. 3D TLC SSDs refer to stacked flash with three bits per cell.
Which is better, 3D NAND or 2D NAND?
Definitely 3D, except maybe in rare cases. It stores more storage capacity per chip at lower cost per GB and requires less energy. Also, its bigger cells suffer from fewer leaks compared to small cells of latest 2D NAND.
Is QLC 3D NAND Bad for an SSD?
No, but it works in some applications better than others. QLC is ideal for gaming collections, media, and backup storage at the lowest cost per TB. If you want an SSD for your system drive that will have a lot of writes, TLC maintains its performance and longevity.
Which NAND technology is the best for an OS Drive?
TLC is the best compromise for most users. It maintains consistent performance once the cache is exhausted and gives good endurance at an affordable price point. SLC and MLC SSDs cost much more and are only practical for very high-write loads.
How many layers does 3D NAND have?
At present, mass-produced chips have between 218 and 321 layers, according to the manufacturer. The companies Kioxia and SanDisk were already sampling chips with 332 layers in 2026, while Samsung is aiming at 1,000 layers in 2030.
Who manufactures 3D NAND?
Almost all 3D NANDs come from five different manufacturers: Samsung, SK Hynix along with Solidigm, Micron, Kioxia, along with SanDisk, and YMTC from China. The drive manufacturers purchase the chips and equip them with controllers and firmware.
Is 3D NAND capable of being SLC?
Yes, as industrial SLC and pSLC products are made using 3D NAND for continuous writing applications. In most consumer SSDs, TLC/QLC flash memory also operates in SLC mode, used as a write cache.
What is the lifetime of 3D NAND?
It depends on the type of cells and amount of writes. Usually, the maximum capacity of a TLC SSD reaches hundreds of TB of written data, which equals many years of its usage.
