i3 | January 08, 2017

2017: The Year Of The Solid State Drive

3D NAND flash is a type of flash memory in which the memory cells are stacked vertically in multiple layers. Flash manufacturers are developing 3D NAND to address challenges in scaling (shrinking) 2D/planar NAND cell technology.

First seen in the Star Trek television series, three-dimensional chess played by Mr. Spock and Captain Kirk used multiple chessboards at different levels, allowing the chess pieces to move in three physical dimensions creating many new moves. The same approach is allowing the flash memory industry to navigate along an attractive cost efficiency curve.

NAND flash memory is built of many cells that hold bits, which are either turned on or off through an electric charge. 3D NAND flash is a type of flash memory in which the memory cells are stacked vertically in multiple layers. Flash manufacturers are developing 3D NAND to address challenges in scaling (shrinking) 2D/planar NAND cell technology.

To squeeze as much as possible out of the planar NAND the industry started with SLC (Single-Level Cell) NAND, which holds one bit of information per cell. MLC (Multi-Level Cell) NAND then was developed holding two bits of information per cell. In 2012, TLC (Triple-Level Cell) NAND-based solid state drives (SSDs) were introduced with three bits of information per cell. The big advantage is the lower cost of manufacturing. Storing three bits of data per cell, TLC flash is the cheapest flash to manufacture. For consumers, TLC-based SSDs mean faster load times for their favorite apps.

But planar NAND flash technology, using a single layer of memory cells, cannot be scaled down much farther on the die’s surface — cell-to-cell interference causes a reduction in the reliability of planar NAND flash products. 3D NAND flash offers the potential for higher capacity in a smaller physical space. The idea to stack the NAND cells with precision could have a dramatic impact by keeping flash storage solutions aligned with Moore’s Law.

What Does It Mean for Consumers?

3D flash could impact everything from smartphones to flash-optimized supercomputers. And while consumers love capacity, price determines adoption. By stacking storage cells to increase capacity through higher density, you get a lower cost per gigabyte. You also get improved electrical use, reducing power consumption, and higher data writing performance with the reliability, speed and performance expected of solid-state memory.

By stacking cells vertically, the cell dimensions of 3D NAND cells can be larger – increasing both performance and endurance – making the designs suited for applications as demanding as a data center storage. As a result, SSDs are making gains in market share at the expense of hard disk drives (HDD). With 3D NAND technology the two key advantages that HDDs have over SSDs – price per gigabyte and storage capacity – are narrowing significantly.

SanDisk and its partner Toshiba, Samsung, and Intel and its partner Micron have created up to 48-layer 3D NAND, storing 32GB in a single chip, paving the way for 3D NAND to erase the storage capacity advantage of HDDs.

Intel and Micron’s 3D NAND technology stacks flash cells vertically in 32 layers to achieve 256GB multilevel cell and 384GB triple-level cell die that fit within a standard package. These capacities can enable gum stick-sized SSDs with more than 3.5TB of storage and standard 2.5-inch SSDs with greater than 10TB.

The largest hard drives top out at 10TB now, with HDD makers Seagate and Western Digital indicating 20TB by 2020. By comparison, the largest SSD based on 3D NAND is Samsung’s 15.36TB product with Intel, Micron, Samsung and Toshiba expecting 48TB and even 96TB drives this year, using a 2.5-inch form factor which occupies 40 percent less volume and is 10 percent lighter than the 3.5-inch form factor for HDDs.

Micron says in 2017, 3D NAND will achieve cost parity with planar NAND and will significantly reduce cost per bit.

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