3D NAND Flash Memory

2016: 3D NAND flash awaits market

In 2016, Intel and Micron Technology will introduce 3D XPoint memory, also known as Optane, which will increase the performance and reliability of hard drives by a thousand times compared to existing NAND flash technology.

Do not write off NAND flash. Despite the fact that everything goes to the fact that the Optane chip and other storage technologies can replace expensive DRAM for many applications, this will not be cheap for a long time. Therefore, there is still an opportunity for further promotion of NAND flash.

Samsung, Intel\Micron Technologies, Toshiba and others believe that 3D NAND flash technology will increase the maximum volume and reduce the cost of hard drives. Ultimately, 3D NAND will even convince consumers that SSDs can be as affordable as HDDs.

"Very soon flash memory will be as cheap as rotating media," says Siva Sivaram, executive vice president of SanDisk.

These technological advances are just the latest chapter in a long history of ever-growing storage needs that are driving innovation to meet new demands.

Earlier, significant advances were made in the non-volatile memory industry to increase maximum volume. A single-level cell (SLC) NAND flash became a multi-level (MLC) NAND, where instead of one bit per transistor, two or three bits were stored. When MLC NAND reached its limit with a 10 nanometer lithographic process, Samsung, followed by Intel/Micron Technologies and Toshiba, introduced 3D NAND flash, which grouped NAND cells as a structure up to 48 levels high. Flash memory manufacturers believe that there is no limit to growth for them.

Although 2D NAND approaches the scaling limit due to size and lithography errors, grouping levels to create 3D NAND bypasses these difficulties. The figure above shows one way to achieve 3D NAND. The horizontally grouped information lines around the central memory opening represent NAND grouped bits. This configuration reduces lithography requirements. The center hole minimizes offset of adjacent bits, and the overall density increases significantly.

NAND flash skyscrapers will grow beyond 100 tiers

Starting with the first iteration, 3D NAND flash technology offered two to ten times higher reliability and twice the recording performance of flat NAND.

More importantly, however, 3D NAND eliminated the lithographic barrier (that the single-level NAND had) that manufacturers encountered once they reduced the size of the transistors below 15 nanometers. A smaller lithographic process resulted in data errors, as bits (electrons) seeped between the thin walls of the cells.

"The important thing is that you don't build these 3D NAND skyscrapers one floor at a time. We know how to go from 24 levels to 36, 48, 64, etc, "Sivaram says. "There are no physical limitations here. What we have now in 3D NAND is predictable scaling of three and four generations - something we've never had before. "

3D Xpoint technology, also known as Optane, is about 1,000 times faster than NAND; a single chip can store up to 128 Gigabits of data.

As of March 2016, Samsung, SanDisk and Toshiba, Intel and Micron Technology are expected to be able to create a 48-level 3D NAND that can store 256 GB (32 GB) on a single chip. Although Samsung is the only company to mass-produce 48-level chips, the rest of the manufacturers plan to launch their products soon.

SanDisk, Sivaram said, has already planned 3D NAND chips with more than a hundred levels.

We don't see a physical limit to how far we can go. If I ask NAND manufacturers how far we can go, they won't tell me that we can get to 96 or 126 levels and that will be the physical limit, "Sivaram said. "It's been our dream for a long time

While the manufacturing facilities to create 3D NAND are far more expensive than flat NAND or HDD production equipment - a single unit could cost $10 billion - Sivaram argues that over time they will optimize the cost as mass production is introduced.

Pricing is key

While businesses and consumers love volume - the more, the better - price most often determines choice.

Intel and its development partner Micron Technology are working on what could be a revolution in the nonvolatile flash memory industry: the Optane chip - known internally from Intel as 3D XPoint.

While Intel has provided little information on what Optane will be, most industry experts believe it's a kind of resistive RAM.

Two-level image of the chip of the resistive RAM architecture 3D XPoint (Optane). This architecture eliminates the need for transistors to store bits and instead uses a array of conductors that use electrical resistance to indicate 1 or 0.

Resistive RAM (ReRAM) is capable of reading and writing operations using 50-100 times less power than NOR flash, making it ideal for mobile devices - even portable ones.

ReRAM is based on the concept of a "memory resistor," also known as a memristor. The term memristor was coined by scientist Leon Chua of the University of California-Berkeley in the early 1970s.

Before the memristor, researchers knew only three basic elements of the circuit - a resistor, a capacitor, and an inductor. Memristor, which uses a lot less power and offers more performance than previous technology, was fourth.

As of March 2016, the only company supplying ReRAM products is Adesto Technologies. She introduced a new conductive bridge RAM chip (CBRAM) for devices focused on energy storage and battery life that are used in the Internet of Things market.

Microscopic photo of the profile of the Resistant RAM circuit, where thin conductive strands intersect and connect to silicone levels to represent a bit of data.

At the same time, Intel plans to provide its Optane drives for personal computer users in 2016. Developed in conjunction with Micron, the new disks are supposed to be 10 times more compact than DRAM, and in theory 1000 times faster and more reliable than NAND SSD.

With a thousand times larger NAND resource, Optane disks will provide one million read-write cycles, which means that the new memory will work almost indefinitely.

"It is not as fast as DRAM, so it will not replace it in most latency-sensitive applications, but it has much more compactness and much less latency compared to NAND," said Russ Mayer, Micron's production director, in an interview with Computerworld. "If you compare how much faster the SSD is compared to the HDD and how much faster the 3D XPoint is compared to traditional NAND, it will be a one-order improvement," Mayer said

Intel has demonstrated that Optane drives work about seven times faster than existing SSDs.

In 2016, Intel also plans to release Optane drives for servers based on its new Skylake processor.

In a row with Optane SSDs, ReRAM technology is expected to be presented as DIMM chips that are inserted into memory slots.

Alan Chen, senior head of research at DRAMeXchange, a division of TrendForce, said that even if Intel's ReRAM technology entered the consumer market for personal computers in 2016, its use would be limited to top-end products due to the high cost.

"Optane's impact on the SSD market will be determined by its price. Currently, Optane products are still more expensive than widespread NAND counterparts. Therefore, they will initially affect only the market of the most expensive SSDs, "Chen is sure.

In 2015, Hewlett-Packard and SanDisk announced an agreement to jointly develop Storage Class Memory (SCM) ReRAM, which could replace DRAM and should be 1000 times faster than NAND flash.

Mexico City startup Knowm is also working to produce memristors.

Knowm's memristor could make it possible to create smart computers that will emulate the work of the human brain.

A new memristor could lead to smart computers that mimic the responses of the human brain.

Knowm's memristors are designed to mimic the human brain in which synapsis connects two neurons. These neurons become stronger as electrical signals pass between them. Similarly, the training and retention of information in Knowm memristors is determined by data flow characteristics and electric current.

Chen revealed that Samsung is also working on Intel's Optane-like technology, which incorporates DRAM and NAND production. Samsung, however, declined to comment.

See also

• DRAM Memory (Global Market)
• NVRAM Non Volatile Random Access Memory
• Ferroelectric RAM, FeRAM, FRAM
• ReRAM - Resistive Random Access Memory
• MRAM (magnetoresistive random access memory)