The fastest growing technology in the storage market continues to be NAND flash. It has capabilities of durability and speed that find favor in both the consumer and enterprise segments, but the key innovation focus for the future of the flash market lies in seeking greater capacity. Though transitioning from planar (2D) to 3D NAND looked highly promising at the time, future capacity gains are proving to be unviable, as increasing writes concurrently decreases the number of times the cell can be programmed, impacting long-term flash capacity. Another option to increase flash capacity is to decrease the cell size. But given that 19 nano-meters (nm) is as small as the industry plans on producing, and we are already at 20 nm on the flash roadmap, this also looks like a dead end.
The greatest opportunity to achieve flash capacity gains is by increasing the number of layers on a chip; however, there are complex issues with building 100-plus layer parts. For this reason and others, there are no vendors talking about building past 136-layers in a single-stack part. So, we predict that future capacity gains in flash will be primarily achieved by string stacking parts together. The string-stacking technique is where multi-layer flash dies are connected together to create a flash chip with more layers. This may result in fewer cost decreases in flash. System and cloud providers will take advantage of the zone-based interface (enabling the physical placement of data into zones matching the performance needs of the data) to get longer life, better performance and greater capacity out of their flash assets.