Today, Samsung announced that it has begun mass production of a new kind of 3D NAND flash memory that offers up higher reliability and write performance versus traditional 2d “planar” technologies. The so-called VNAND (Vertical NAND) is currently being used in 128Gb (Gigabit) flash chips (matching current 2D flash chips), but the technology has the potential to go much further in terms of capacity.
The VNAND combines an updated version of Samsung’s Charge Trap Flash (CTF) technology (originally developed in 2006) with a vertical stacking and interconnect technology that uses special etching techniques to punch holes and electrical connections down from the top of the highest die to the bottom die.
Samsung claims that its proprietary interconnect technology is (currently) able to support up to 24 layers of flash memory. The resulting VNAND offers up to twice the write performance and between 2-times and 10-times higher reliability versus traditional 19nm floating gate NAND (the alternative to CTF NAND) developed on planar processes.
With traditional NAND flash, as flash density increases (such as the move from 25nm to 19nm NAND flash), inter-cell interference also increases due to thinner walls and increased leakage. Samsung is hoping to solve that problem with its vertically-stacked NAND by allowing density to increase without dealing with shrinking the individual layers. Further, each layer is separated by a dielectric (electric insulator) that is currently 50nm and constructed of Silicon Nitride (SiN). The company notes that there is a limit to the height at which flash can be stacked before it becomes un-economical, but that is still a ways off compared to where NAND flash is now as far as densities seen in the wild.
Samsung’s new 128Gb VNAND chip is expected to scale to at least 1Tb depending on consumer demand. The technology is aimed at both embedded NAND and SSDs, but the former is likely to make use of 3D vertical NAND first. Standard 2.5" SSDs could also benefit but modern SSDs are already bottle-necked by the SATA III 6Gbps bus much less by faster write speed potential. Mobile devices, however, could benefit from faster single-chip VNAND packages immediately with faster write speeds and higher reliability (and potentially, density) versus 2D NAND chips.
It is definitely a technology with potential that is worth keeping an eye on.
The full press release can be found over at Engadget.