Evolution of NAND Flash
The NAND flash market is evolving rapidly. As triple level cell (TLC) NAND flashes have established itself as the mainstream in the market, it is expected that the next generation of quad level cell (QLC) NAND flashes, which can contain more information at a lower price, will be in full bloom.
According to IHS Markit, a semiconductor market research company on October 8, TLC NAND flashes accounted for 65% of the global NAND flash market as of the end of the third quarter, exceeding multi-level cell (MLC) NAND flashes (37.5%). Given the fact that TLC NAND flashes and MLC NAND flashes accounted for 56.1% and 43.6% of the market, respectively, at the end of 2016, the market has been shifting rapidly toward TLC NAND flashes this year.
This phenomenon is expected to gain more ground in the future. IHS Markit expects TLC NAND flashes to account for 70% of the total market by the end of next year.
At the moment, NAND flashes in the market are divided into single level cell (SLC), MLC and TLC NAND flashes according to technological systems. In a 'cell' that is a space for storing data in a NAND flash, an SLC NAND flash stores one-bit data, and an MLC NAND flash and a TLC NAND flash store two- and three-bit data, respectively.
In order to put a lot of data into one cell, the process must be finer. An SLC NAND flash requires two gates that can distinguish between 1 and 0 in one cell but an MLC NAND flash and a TLC NAND flash needs to be segmented to have four and eight gates.
This also increases difficulties in development and manufacturing. However, more data can be stored on wafers of the same size, which can significantly mark down prices. In order to popularize solid state drives (SSD), it is essential to lower prices of NAND flashes, a key component for SSDs.
In the early stage of TLC NAND flash introduction, there was a lot of concern about stability. As its line width narrowed considerably, malfunctions and product life became big issues. However, NAND makers’ technological advancement such as 3D and ultra-fine nano processes boosted stability, eliminating problems in general use.
Global NAND flash makers such as Samsung Electronics are expected to introduce QLC NAND flashes to the market beginning next year. QLC NAND flashes stores four bits of data in one cell. QLC NAND flashes can lower prices by scaling up their integration level and expanding their storage capacities, compared to other NAND flashed based on conventional methods.
"QLC NAND flashes are not yet in mass-production, but we are preparing it internally," said an official at Samsung Electronics. "QLC NAND flashes can store four times as much data as SLC NAND flashes."
Other NAND flash makers such as Toshiba and SK Hynix are also reportedly preparing for QLC NAND flash production.
IHS Markit expects QLC NAND flashes to make a debut in the market in the first quarter of 2018 and gradually increase its market share to 5.1% of the overall market by the end of 2018. QLC NAND flashes will account for 30% in 2021, dividing the NAND flash market with TLC NAND flashes.
"High-priced SLC NAND flashes are expected to be limitedly used in special cases," an industry source said. "TLC NAND and QLC NAND flashes to be launched will the mainstream in the market."