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Name: Junlin Lu
ITU ID: 95014
Advisor: Dr. QING ZHU
3D XPoint Memory Technology
Abstract
3D XPoint is up to 1,000 times faster and has up to 1,000 times greater
endurance than NAND, and is 10 times denser than conventional
memory.
Introduction
3D XPoint (pronounced three dee cross point) is a non-volatile memory
technology announced by Intel and Micron in July 2015[1]
. 3D XPoint
technology combines the performance, density, power, non-volatility
and cost advantages of all available memory technologies on the market
today. The technology is up to 1,000 times faster and has up to 1,000
times greater endurance than NAND, and is 10 times denser than
conventional memory. 3D XPoint technology is a major breakthrough in
memory process technology and the first new memory category since
the introduction of NAND flash in 1989.
This report is about the 3D XPoint memory technology, and the report
will go cover the memory cell structure, comparison between XPoint and
NAND/DRAM, production, issue, and conclusion.
Memory Cell Structure
XPoint is made from Phase Change Memory material, a chalcogenide
glass, and it has electricity applied to it, causing a bulk change in some
aspect of its state that causes a resistance-level change. This can be
reversed, leading the resistance levels signaling a binary 1 or zero. The

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XPoint die has two layers and a crossbar design, hence its full 3D
CrossPoint name.
3D is a representative of this structure can be directly stacked to
increase the storage density; XPoint stands for Cross Point to express the
structure of the cross, and no internal transistor. The internal storage
structure of 3D XPoint can be divided into 2 layers, one layer, the upper
layer, is the Selector, and the other one layer, the lower layer, is the
actual Memory Cell. These 2 layers of material are stacked in the
semiconductor process. And then, the memory cells are cross-connected
with metal wires to form the word lines and bit lines of 3D XPoint
structure. The data storage mechanism of Memory Cell in 3D XPoint is
not using the charge storage mechanism used by today's non-volatile
memory, but transforming itself into different characteristics. Currently,
each die cut from the first batch of the production of wafers has 128Gb
storage capacity. [2]
Comparison between XPoint and NAND/DRAM

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XPoint technology combines the performance, density, power, non-
volatility and cost advantages of all available memory technologies on
the market today. The technology is up to 1,000 times faster and has up
to 1,000 times greater endurance than NAND, and is 10 times denser
than conventional memory.
XPoint latency is much better than NAND, and close to DRAM. In an
NVMe-based solid state drive, XPoint chips can deliver more than 95,000
I/O operations per second at a 9 microsecond latency, compared to
13,400 IOPs and 73 ms latency for flash. That should open up a variety of
applications from servers running big-data analytics and machine
learning to high-end games machines.
[3]
XPoint endurance is better than NAND, and worse than DRAM. Intel and
Micron are claiming that 3D XPoint provides up to a
thousand times higher endurance than NAND. Assuming that the

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numbers are relative to modern (15-20nm) MLC NAND, the endurance
should be in the order of a few million P/E cycles; though the marketing
materials are claiming up to tens of millions of write cycles. If we assume
3 million write cycles (1000x of what modern MLC has), a 256GB 3D
XPoint based drive would have a total write endurance of 768 petabytes.
That's equivalent to 420TB per day for five years, or 4.9GB per
second. For storage applications that currently rely on NAND, 3D XPoint
will eliminate any potential endurance concerns, but it's not durable
enough to challenge DRAM in that front since DRAM endurance is
essentially infinite. Whether 3D XPoint provides enough endurance to
replace DRAM ultimately depends on the application, but especially in
certain enterprise workloads there's a need for DRAM.[4]
DRAM 3D XPoint NAND
Endurance (P/E
Cycles)
10^15 10^7 10^3
Read Latency Nanoseconds 10s of
Nanoseconds
~100
Microseconds
Production
3D XPoint is the technology. Optane is the brand for SSDs using 3D
XPoint. The first product from that Optane (XPoint) storage line could be
arriving in Q1 2017. the new drives as “Mansion Beach” and “Brighton
Beach.” They are both Optane SSDs that utilize PCIExpress 3 x4 and x2
ports, respectively. As part of the “Enthusiast workstation” range, we
would expect prices on those drives to be quite steep initially, much like
the Intel SSD 750 series.
Issues
3D XPoint failure modes. Large scale deployment always discovers bugs
and issues that even diligent betas won't find. We are not sure whether
the XPoint could arrive on time.

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Besides, after the mass production, whether the density, performance,
and endurance of XPoint could still be as good as the current number is
questionable.
Conclusion
Even though there are many problems and concerns existed, however,
the 3D XPoint memory technology could be the future of the memory
and storage and it fundamentally changes the structure of memory and
storage field. It is very excited to see when the XPoint production arrives
in the near future, and it is excited to see how the XPoint may share the
market of DRAM and NAND.

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Reference:
[1] 3D XPoint,
https://en.wikipedia.org/wiki/3D_XPoint
[2] Intel and Micron jointly launched a new structure of non-volatile
memory, called 3D XPoint,
http://www.micro-ip.com/msg.php?mode=show&cid=5&id=27
[3] Joel H. (2015), Intel, Micron reveal Xpoint, a new memory
architecture that could outclass DDR4 and NAND
http://www.extremetech.com/extreme/211087-intel-micron-reveal-
xpoint-a-new-memory-architecture-that-claims-to-outclass-both-ddr4-
and-nand
[4] Kristian V. (2015), Analyzing Intel-Micron 3D XPoint: The Next
Generation Non-Volatile Memory,
http://www.anandtech.com/show/9470/intel-and-micron-announce-3d-
xpoint-nonvolatile-memory-technology-1000x-higher-performance-
endurance-than-nand