i3 - January/February 2017 - 16

Tech

By Murray Slovick

A T EC H TO WATC H

irst 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 (TripleLevel 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
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JANUARY/FEBRUARY 2017

three bits of data per cell, TLC flash is the
cheapest flash to manufacture. For consumers TLC based SSDs means 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 caused
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 2.5inch 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 15.36 TB 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. n
I T I S I N N O VAT I O N

COURTESY EVERETT COLLECTION

3D NAND Technology: 2017 The Year
Of The Solid State Drive

i3 - January/February 2017

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