Multi-level cell: Difference between revisions

Revision as of 12:41, 21 June 2025

Latest revision as of 05:48, 6 August 2025

(One intermediate revision by one other user not shown)

Line 1:

{{short description|Memory cell capable of storing more than a single bit of information}}

{{Contradicts other|Memory cell (computing)|date=June 2025}}

[[File:Cell types SLC-PLC in comparison 20211102.svg|350px|thumb|right|alt=SLC, MLC, TLC, QLC, PLC shown with all possible bit combinations per cell type|The differences of the memory cells in comparison]]

In [[electronics]], a '''multi-level cell''' ('''MLC''') is a [[memory cell (computing)|memory cell]] capable of storing more than a single [[bit]] of information{{Contradictory inline|here|Memory cell (computing)|date=June 2025}}, compared to a '''single-level cell''' ('''SLC'''), which can store only one bit per memory cell. A memory cell typically consists of a single [[floating-gate MOSFET]] (metal–oxide–semiconductor field-effect transistor), thus multi-level cells reduce the number of MOSFETs required to store the same amount of data as single-level cells.

'''Triple-level cells''' ('''TLC''') and '''quad-level cells''' ('''QLC''') are versions of MLC memory, which can store three and four bits per cell respectively. The name "''multi''-level cell" is sometimes used specifically to refer to the "''two''-level cell". Overall, the memories are named as follows:

Line 24 ⟶ 23:

A single-level cell (SLC) flash memory may have a lifetime of about 50,000 to 100,000 program/erase cycles.<ref>{{Cite web |title=Hyperstone Blog {{!}} NAND Flash is displacing hard disk drives |url=https://www.hyperstone.com/en/NAND-Flash-is-displacing-hard-disk-drives-1249.html |access-date=2023-02-11 |website=Hyperstone GmbH |language=en}}</ref>

A single-level cell represents a 1 when almost empty and a 0 when almost full. There is a region of uncertainty (a read margin) between the two possible states at which the data stored in the cell cannot be precisely read.<ref name=":0">{{Cite web |last=Shimpi |first=Anand Lal |title=The Intel SSD 710 (200GB) Review |url=https://www.anandtech.com/show/4902/intel-ssd-710-200gb-review |archive-url=https://web.archive.org/web/20111001233340/http://www.anandtech.com/show/4902/intel-ssd-710-200gb-review |url-status=dead |archive-date=October 1, 2011 |access-date=2023-02-11 |website=www.anandtech.com}}</ref>

== Multi-level cell ==

Line 51 ⟶ 50:

With current technology a maximum lifetime of up to 3,000 program/erase cycles is achievable.<ref name="lifetime">{{cite web |title=Difference between SLC, MLC, TLC and 3D NAND in USB flash drives, SSDs and Memory cards |url=https://www.kingston.com/en/blog/pc-performance/difference-between-slc-mlc-tlc-3d-nand |website=Kingston Technologies |access-date=8 February 2024 |date=May 2021}}</ref>

[[Samsung]] announced a type of NAND flash that stores 3&nbsp;bits of information per cell, with 8&nbsp;total voltage states (values or levels), coining the term "triple-level cell" ("TLC"). [[Samsung Electronics]] began mass-producing it in 2010,<ref name="samsung-history">{{cite web |title=History |url=https://www.samsung.com/us/aboutsamsung/company/history/ |website=[[Samsung Electronics]] |publisher=[[Samsung]] |access-date=19 June 2019}}</ref> and it was first seen in Samsung's 840 Series [[Solid-state drive|SSDs]].<ref>{{Cite web |url=http://www.samsung.com/global/business/semiconductor/minisite/SSD/uk/html/about/MlcNandFlash.html |title=Samsung SSD 840 Series – 3BIT/MLC NAND Flash |access-date=2013-04-10 |archive-url=https://web.archive.org/web/20130410070908/http://www.samsung.com/global/business/semiconductor/minisite/SSD/uk/html/about/MlcNandFlash.html |archive-date=2013-04-10 |url-status=live }}</ref> Samsung refers to this technology as 3-bit MLC. The negative aspects of MLC are amplified with TLC, but TLC benefits from still higher storage density and lower cost.<ref>{{cite web |url=http://www.anandtech.com/show/6459/samsung-ssd-840-testing-the-endurance-of-tlc-nand |archive-url=https://archive.today/20140405031502/http://www.anandtech.com/show/6459/samsung-ssd-840-testing-the-endurance-of-tlc-nand |url-status=dead |archive-date=April 5, 2014 |title=Samsung SSD 840: Testing the Endurance of TLC NAND |publisher=AnandTech |date=2012-11-16 |access-date=2014-04-05}}</ref>

In 2013, Samsung introduced [[V-NAND]] (Vertical NAND, also known as 3D NAND) with triple-level cells, which had a memory capacity of 128{{nbsp}}[[Gibibit|Gbit]].<ref name="tomshardware">{{cite news |title=Samsung Mass Producing 128Gb 3-bit MLC NAND Flash |url=https://www.tomshardware.co.uk/NAND-128Gb-Mass-Production-3-bit-MLC,news-43458.html |access-date=21 June 2019 |work=[[Tom's Hardware]] |date=11 April 2013 |archive-date=21 June 2019 |archive-url=https://web.archive.org/web/20190621175628/https://www.tomshardware.co.uk/NAND-128Gb-Mass-Production-3-bit-MLC,news-43458.html |url-status=dead }}</ref> They expanded their TLC V-NAND technology to 256{{nbsp}}Gbit memory in 2015,<ref name="samsung-history"/> and 512{{nbsp}}Gbit in 2017.<ref name="anandtech-samsung">{{cite news |last1=Shilov |first1=Anton |title=Samsung Starts Production of 512 GB UFS NAND Flash Memory: 64-Layer V-NAND, 860 MB/s Reads |url=https://www.anandtech.com/show/12120/samsung-starts-production-of-512-gb-ufs-chips |archive-url=https://web.archive.org/web/20171205221122/https://www.anandtech.com/show/12120/samsung-starts-production-of-512-gb-ufs-chips |url-status=dead |archive-date=December 5, 2017 |access-date=23 June 2019 |work=[[AnandTech]] |date=December 5, 2017}}</ref>

Enterprise TLC (eTLC) is a more expensive variant of TLC that is optimized for commercial use.

Line 67 ⟶ 66:

SanDisk X4 flash memory cards, introduced in 2009, was one of the first products based on NAND memory that stores 4&nbsp;bits per cell, commonly referred to as quad-level-cell (QLC), using 16 discrete charge levels (states) in each individual transistor. The QLC chips used in these memory cards were manufactured by Toshiba, SanDisk and [[SK Hynix]].<ref>{{Cite web |last=McGlaun |first=Shane |date=2009-10-13 |title=SanDisk Ships World's First Memory Cards With 64 Gigabit X4 NAND Flash |url=https://www.slashgear.com/sandisk-ships-worlds-first-memory-cards-with-64-gigabit-x4-nand-flash-1360217/ |access-date=2023-02-11 |website=SlashGear |language=en-US}}</ref><ref>{{Cite web |last=Choi |first=Young |date=2009-05-05 |title=NAND Flash &#45 The New Era of 4 bit per cell and Beyond |url=https://www.eetimes.com/nand-flash-45-the-new-era-of-4-bit-per-cell-and-beyond/ |access-date=2023-02-11 |website=EE Times}}</ref>

In 2017, Toshiba introduced V-NAND memory chips with quad-level cells, which have a storage capacity of up to 768{{nbsp}}Gbit.<ref>{{cite news |title=Toshiba Develops World's First 4-bit Per Cell QLC NAND Flash Memory |url=https://www.techpowerup.com/234729/toshiba-develops-worlds-first-4-bit-per-cell-qlc-nand-flash-memory |access-date=20 June 2019 |work=TechPowerUp |date=June 28, 2017}}</ref> In 2018, [[ADATA]], [[Intel]], [[Micron Technology|Micron]] and Samsung have launched some SSD products using QLC NAND memory.<ref>{{Cite web|url=https://www.anandtech.com/show/13606/adata-ultimate-su630-ssd-3d-qlc-for-sata|archive-url=https://web.archive.org/web/20181116032401/https://www.anandtech.com/show/13606/adata-ultimate-su630-ssd-3d-qlc-for-sata|url-status=dead|archive-date=November 16, 2018|title=ADATA Reveals Ultimate SU630 SSD: 3D QLC for SATA|last=Shilov|first=Anton|website=AnandTech.com|access-date=2019-05-13}}</ref><ref>{{Cite web|url=https://www.anandtech.com/show/13078/the-intel-ssd-660p-ssd-review-qlc-nand-arrives|archive-url=https://web.archive.org/web/20180807184625/https://www.anandtech.com/show/13078/the-intel-ssd-660p-ssd-review-qlc-nand-arrives|url-status=dead|archive-date=August 7, 2018|title=The Intel SSD 660p SSD Review: QLC NAND Arrives For Consumer SSDs|last=Tallis|first=Billy|website=www.anandtech.com|access-date=2019-05-13}}</ref><ref>{{Cite web|url=https://www.anandtech.com/show/13512/the-crucial-p1-1tb-ssd-review|archive-url=https://web.archive.org/web/20181108183225/https://www.anandtech.com/show/13512/the-crucial-p1-1tb-ssd-review|url-status=dead|archive-date=November 8, 2018|title=The Crucial P1 1TB SSD Review: The Other Consumer QLC SSD|last=Tallis|first=Billy|website=www.anandtech.com|access-date=2019-05-13}}</ref><ref>{{Cite web|url=https://www.anandtech.com/show/13170/samsung-starts-mass-production-of-qlc-vnandbased-ssds|archive-url=https://web.archive.org/web/20180809105552/https://www.anandtech.com/show/13170/samsung-starts-mass-production-of-qlc-vnandbased-ssds|url-status=dead|archive-date=August 9, 2018|title=Samsung Starts Mass Production of QLC V-NAND-Based SSDs|last=Shilov|first=Anton|website=AnandTech.com|access-date=2019-05-13}}</ref>

In 2020, Samsung released a QLC SSD with storage space up to 8&nbsp;TB for customers. It is the SATA SSD with the largest storage capacity for consumers as of 2020.<ref>{{Cite web |title=Samsung 870 QVO SATA 2.5" SSD |url=https://semiconductor.samsung.com/consumer-storage/internal-ssd/870qvo |access-date=2023-02-11 |website=Samsung Semiconductor Global |language=en}}</ref><ref>{{cite web |url=https://news.samsung.com/global/samsung-electronics-debuts-industry-leading-8tb-consumer-ssd-the-870-qvo |title=Samsung Electronics Debuts Industry-Leading 8TB Consumer SSD, the 870 QVO |website=Samsung Newsroom}}</ref>