The future of NAND technology
on Sep 19, 2019
The volume of digital data is growing at a phenomenal pace, as mobile devices become ever more embedded in our everyday lives, while digital solutions continue to replace traditional systems. With the emergence of 5G technology, the exponential growth in global data demand shows no signs of stopping. By the year 2025, experts estimate that the world’s data will increase by 61% to a staggering 175 zettabytes.
The data explosion is pushing current memory technology to the limit. Samsung has answered the call for more effective memory solutions with its cutting-edge 4bit vertical-NAND (V-NAND) technology. Featuring a groundbreaking three-dimensional structure, the high-capacity V-NAND technology provides a reliable foundation to meet current and future data demands.
The Limitations of planar NAND Technology
The capacity of a NAND flash drive depends on the number of cells in the chip. Until recently, manufacturers have focused on fitting smaller cells in a planar NAND structure, where memory cells are placed adjacent to one another in a single die layer, to boost memory capacity. In just 15 years, cell size has reduced from 120 nm to 19 nm, while capacity has increased by 100 times.
Shrinking cell size, however, throws up several technical challenges. Firstly, photolithography, the current process used to create a circuit, will eventually reach its limit, meaning that cells could not be shrunk any further. Secondly, when memory cells drop below 20 nm in size, the chances of an electrical charge leaking from one cell to another increases significantly. This cell-to-cell interference can cause data corruption, drastically compromising the reliability of a flash memory.
V-NAND: The Next-Generation Memory Solution
Samsung’s V-NAND technology is designed to overcome the limitations of planar technology, expanding capacity without reducing reliability. Instead of trying to squeeze more cells into an ever-decreasing area, V-NAND technology builds upwards by stacking cells on top of one another.
The unique structure of V-NAND is made possible by Channel Hole Technology. It connects cells via a cylindrical channel and allows over 100 layers of cells to be stacked. The result is much greater cell density. While planar NAND design has a maximum component density of 128 Gb, the V-NAND structure expands the limit to 1 Terabit (Tb).
In addition to its innovative structure, V-NAND also employs Charge Trap Flash (CTF) technology to eliminate cell-to-cell interference. By introducing a non-conductive layer of silicon nitride to the cells, CTF technology makes V-NAND technology immune to electrical charge leakages and data corruption.
Since V-NAND no longer has to prevent data corruption caused by electrical leakages, the flash memory can run more efficient program algorithms. The simplified algorithms, in turn, allow the flash memory to write data two times faster than planar NAND flash memory, while substantially reducing its power consumption. With a reduced electric field and superior voltage distribution, V-NAND’s unique structure also makes the memory solution more durable and less error-prone.
Setting a New Performance Standard
V-NAND based SSD has continued to evolve since it was first introduced in 2013, and the recent unveiling of the 250 GB SATA SSD with sixth-generation V-NAND memory technology marks yet another significant milestone in the technology’s development.
The sixth-generation V-NAND features 136 layers, increasing the number of cells by around 40 percent from its predecessor. To minimize errors and read latencies that usually come with height increase, Samsung adopted a new speed-optimized circuit design, which enables the chips to offer data transfer speed at below 450 microseconds (μs) for write operations and below 45 μs for reads.1) Compared to the the previous generation, the sixth-generation V-NAND is over 10 percent faster and consumes approximately 15 percent less energy.2)
In addition to enhancing performance, Samsung also modified V-NAND to make it easier to manufacture. With the sixth-generation V-NAND, the number of channel holes required for a 256Gb chip has decreased from 930 million to 670 million, improving manufacturing productivity by approximately 20 percent.
Designed to overcome the limits of traditional memory solutions, Samsung’s V-NAND technology holds the key to unlocking the potential of our data-driven world. The advances made with the sixth-generation V-NAND will allow Samsung to take the next step in improving the memory technology. This speed-optimized design, in particular, will be critical in the development of V-NAND solutions with over 300 layers. From capacity to performance, the revolutionary flash technology is perfectly suited for today’s and tomorrow’s data demands.
1) This result is measured under typical computing environment
2) The previous generation V-NAND offers data transfer speed at below 500 microceconds (μs) for write operations and below 50 μs for reads, and comsumes approximately 16.9 milliampere (mA) while the sixth-generation V-NAND consumes approximately 13.8 milliampere (mA).