Page 23

EETE FEB 2016

memory Micron 3-D NAND back to Moore By R. Colin Johnson Flash memory is back on the Moore’s Law scaling curve, according to Micron Technology Inc. (Boise, Idaho) thanks to its move into three-dimensional structures. “3D gets NAND back on a regular scaling curve,” Kevin Kilbuck, Micron’s director of NAND Strategic Planning told EE Times. “Our first generation is 32 layers in the vertical direction while relaxing the x-y design rules back several generations.” Prior to going 3D, Micron could only shrink each new generation in its x-y dimensions, but they hit the wall at 20-nanometers, only able to shrink in one direction—either x or y—at the 16-nanometer node. But by going 3D, Micron has been able to keep increasing chip capacity per package while relaxing the x-y scaling rules. Relaxing the x-y design rules improves the performance and reliability compared with sub-20nm planar NAND. “As you approach the x-y scaling limit, you start running out of electrons and get a lot more interference,” Kilbuck told us. “Going 3D solved that problem for us, while still keeping the packages in the 1.0-to-1.4 millimeter range with the same pinout.” In its fabs in Singapore and Lehi, Utah (half-owned by Intel) Micron’s first generation 3D NAND chips will be 32- and 48-gigabytes. With up to 16 layers in a single package super high density solid-state drives (SSDs) can be made for servers and data centers. For the future, Micron plans 2-terabyte 3D NAND packages, allowing an SSD using 16 of them to pack up to 32-terabytes. “Our solution is the first 3D NAND technology built on a floating gate cell,” Kilbuck told EE Times. “It also has an architecture enabling industry-leading monolithic MLC and TLC die. Unlike competitive solutions, our first-generation 3D NAND is architected to achieve better cost efficiencies than planar NAND. For consumer and mobile markets, lower density and much less expensive 3D NAND packages are also envisioned. 3D XPoint Micron also has its 3D XPoint (pronounced cross-point) chips coming online in 2016. The 3D XPoint was developed with Intel Micron’s 3-D NAND die is small enough to boost solid-state SSDs the size of gum sticks to 3.5 terabytes. (Source: Micron) to realize a dream that IEEE Fellow Leon Chua, Hewlett Packard, Hynix and innumerable startups have been trying to realize for a decade—a high-density transistor-less memory cell. The idea is to put a material that increases its resistance whenever current is put through it in one direction, and reduces its resistance when current flows the opposite direction. Many such materials—called memristors by their inventor Chua—have been successfully tested in the lab, from exotics to plain-old silicon dioxide, but no one has been able to perfect the read/write process for mass production—until now. Micron, with the help of Intel, promised to be sampling to major customers its ultra-high-density 3D XPoint chips in 2016, each layer of which will consist of a cross-bar array of word- and bit-lines with their proprietary secret-sauce material in-between. Sometimes called resistive RAMs (Re-RAMs or just RRAMs) Micron/Intel claim to have finally worked out the kinks plus be able to stack XPoint layers atop each other for 3-D calibre densities. So far they are keeping their secret-sauce resistance changing material a secret, but their pitch is that in the end 3D XPoint will be ultra-dense, close to DRAM in performance, but closer to flash in cost. High performance solid-state drives will be the first beneficiaries, according to Kilbuck, filling the gap between “storage and memory” for data centers. Later consumer versions will be introduced circa 2018 after mass production has reduced their price closer to flash based SSDs. 3D NAND wafer close-up reveals Micron and Intel unveil new 3D NAND technology with three times higher capacity than other NAND dies in production. (Source: Micron, used with permission) Micron 3D XPoint memory uses a resistive material between a highly dense crossbar array to change 0s to 1s with current. (Source: Micron) www.electronics-eetimes.com Electronic Engineering Times Europe February 2016 23


EETE FEB 2016
To see the actual publication please follow the link above