2016 may be shaping up to be the year memory makers commit to upping 3D NAND production in a bid to replace its planar predecessor.

Micron announced its 3D NAND technology is now available in multi-level cell (MLC) and triple level cell (TLC) products, and expects by the second half of the year that the majority of its total NAND flash output to be on 3D NAND as designers build devices such as laptops, tablets and servers that need its increased capacity, performance and power.

SSDs are the obvious opportunity for 3D NAND, said Kevin Kilbuck, Micron's director of NAND strategic planning, particularly enterprise storage. The company is sampling 3D NAND-based client SSDs this month that will be generally available in June. It will also find its way into embedded markets such as automotive, industrial, and mobile devices as well as Internet of Things devices, he told EE Times in a telephone interview.

Micron has begun volume production of 256Gb MLC and 384Gb TLC that can be stacked and put into an SSD. Kilbuck said Micron can get 3.5 TB into an m.2 form factor and 10 TB in a 2.5-inch form factor. He said Micron has made some architectural innovations to further reduce the cost of 3D NAND, noting that XY lithography is now becoming irrelevant. “3D NAND sets the clock back. We are able to relax the XY lithography. It's how high can you stack it."

One of the changes Micron was able to make was the ability to hide more than 75% of the CMOS logic under the array with its 32-tier 256Gb MLC/384Gb TLC 3D NAND products.

Kilbuck said Micron chose to stick with floating gate technology, which has been around since the early days of flash and used for EEPROM and NOR, noting there have been issues with the charge trap approach, such as charge loss which affect retention. “We didn't want to have to solve those issues while stacking." It made sense to stack a known entity, he said, rather than exponentially stretch the learning curve. “It was a matter of de-risking our schedule and deployment plans."

What will also contribute to 3D NAND's uptake in 2016 is that there is a supporting ecosystem for the technology, said Kilbuck, with companies such as PMC Sierra and Silicon Motion providing controllers. Silicon Motion introduced a turnkey merchant SATA SSD controller supporting 3D NAND from multiple vendors, including Micron, earlier this year at CES. It supports provisioning of higher capacity SSDs, from a broad range of vendors, up to 2TB.

Kilbuck said Micron staff responsible for ecosystem enablement started visiting controller partners a couple of years ago to share and discuss its roadmap for 3D NAND.

While 3D NAND is often labelled as revolutionary because of its potential for reduced cost and increased density, Kilbuck said in many ways, including from a controller standpoint, it's just a natural evolution from its predecessor. "It's still NAND to the controller. There may be a few more features to deploy but it's still fundamentally a pretty evolutionary change for them."

There are several controllers ready to handle Micron's 3D NAND depending on the market segment for flash cards, client SSD and enterprise SSDs, said Kilbuck. The initial densities Micron is manufacturing are well above what is used in embedded applications. Meanwhile there is lots of room for SSD growth in the notebook segment, he said, and the enterprise space as organizations still haven't completely moved away from spinning disk in the data center.

Kilbuck said 2016 is the year of 3D NAND, but more specifically, it's an investment year as vendors look to ramp up and make it more cost-effective to produce than 2D NAND. “Planar is hitting the end of its wall. There are still a few more shrinks left."

He acknowledged there are tradeoffs when moving to 3D NAND—there are more process steps and wafer costs go up. “Once you get some scale behind it, no wants to be on the old technology."

Micron announced with Intel last March that together they would be second to Samsung with ultra-dense 3D NAND flash chips that will sell as chips and in SSDs. Not long after, Toshiba announced it was shipping samples of its 48-layer 3D Bit Cost Scalable (BiCS) stacked cell structure flash.

By: DocMemory
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