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Samsung, SK Hynix and Kioxia continue with 3D TLC for SSD

Of the top six manufacturers of 3D NAND Flash in the world (if we count WD as independent), three of them are going to bet once again on TLC NAND Flash instead of launching new technologies based on QLC. The big question in the middle of 2021 is, why do they keep releasing new versions of NAND Flas from 3 bits if what is sought is to increase the capacity and reduce the cost?

Samsung, SK Hynix and Kioxia have new 3D TLC: denser, faster and with lower latency

Samsung 2021 Samsung 2019 SK Hynix Kioxia 2021 Kioxia 2019 Kioxia 2018
Layers 128 176 162 128 96
Capacity per die 512 Gb 512 Gb 512 Gb 1 Tb 512 Gb 512 Gb
Size per die in mm2 101.58 98 66 86
Density (Gbit / mm2) 8.5 5 10.8 10.4 7.8 5.95
Input and Output Speed 2 Gb / s 1.2 Gb / s 1.6 Gb / s 2 Gb / s 1,066 Gb / s 533 Mb / s
Performance 184 MB / s 82 MB / s 168 MB / s 160 MB / s 132 MB / s 57 MB / s
Read latency (tR) 40 µs 45 µs 50 µs 50 µs 56 µs 58 µs
Block erasure 24 MB 18 MB
Plans Supposedly 4 two 4 4 4 two
CuA / PuC Yes Do not Yes Yes Yes Do not

It is extremely surprising that of all the extremely large manufacturers in the NAND Flash market, only Intel has been able to update the QLCs for this year. Meanwhile, the rest of the market continues with TLC as a priority objective and according to the table above, there are important advances.

The most striking thing without a doubt is the leap that Samsung has made (finally) with its 3D TLC since 2019 and after leaving 2020 as a transition. We are talking about an indeterminate number of layers yes (they have not wanted to specify it, but it is rumored that they are below 170), but the density has increased a surprising 70% and the speed has almost doubled for its IOs as well as the average throughput per cell exceeding the 100%.

Where Samsung continues to reign above the rest is in the so-called Stacking, the main technique to create CMOS like NAND Flash for vertical channels, which indicate from density to number of layers, since the more layers you can include in each single deck »Instead of using two decks, you reduce the steps required to manufacture the cells in the fabs, lowering the cost and increasing the speed.

However, SK Hynix and Kioxia they are quite even and have taken similar paths, saving the capacity of the die. The densities are almost identical, as well as the rate per cell or the latencies. This has been made possible by an average improvement of 10% in the horizontal density of the cells, so we are talking about vertical channels that are surely quite similar in design and shape.

Only Intel innovates in QLC for this 2021

Intel presented just two weeks ago all the data of its first generation 3D NAND Flash that has not been developed by Micron in conjunction with its association, as has been customary until now. These new QLC 144L have reduced the size of their matrix to 74 mm2 and increased its density to 13.8 Gbit / mm2, which represents an increase in 55% in just one year.

His performance takes off at the level of his rivals in TLC: 1.2 Gb / s, but per cell they only get 40 MB / s, far behind 3-Bit cells, but which also means being industry leaders, doubling, for example, Samsung’s performance.

In terms of latencies, the average tRs have been reduced to 85 pico seconds and at most they will face 128 pico seconds, the lowest ever developed, but still far from TLC. Considering the comparative data, it is understood why manufacturers are focusing on TLC given the new platforms that are about to hit the market.

The average user wants a little more capacity and above all speed, data centers just the opposite, so each company is fighting for a piece of the cake, less Intel that walks alone for this 2021 and will be able to convince more than one company and data center for you to choose to buy Optane with 144-layer QLC.

We mortals will settle for TLC and better performance per cell to exploit the PCIe 4.0 bus through new M.2s that promise to collapse its performance after two years with us. From what it seems, it will be WD with Kioxia that has the most complete device in general terms, but Samsung will be able to react on prices, so the war will be very entertaining.