information storage and spintronics 08ah566/lectures/info08_flash.pdf · department of electronic...

Department of Electronic Engineering

Information Storage and Spintronics08

Atsufumi Hirohata

13:30 Monday, 26/October/2020 (B/B 006 & online) & 12:00 Thursday, 29/October/2020 (online)

Quick Review over the Last LectureOptical recording : *

Initial crystallised phase

Written amorphous phaseR:大

R:小Writing

Reading

Laser spot

Written data bits

* https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=2ahUKEwiQpNDA-__jAhVFoVwKHWGIDssQFjAAegQIARAC&url=http%3A%2F%2Fhome.sato-

gallery.com%2Feducation%2Fkouza%2FRyukoku_lecture.ppt&usg=AOvVaw0UTNH3qZH_LSTZ0vsF3Hxx/

** http://ffden-2.phys.uaf.edu/211.fall2000.web.projects/J%20Kugler/mo.html

( )

( )Magneto-optical recording : **

( ) ( )

( )

( )

( )

( )

08 Flash Memory

• NOR flash

• NAND flash

• TSV

•Multiple value

• SONOS

Performance Gap between HDD and DRAM

* http://www.theregister.co.uk/2013/06/25/wd_shingles_hamr_roadmap/

Flash MemoryIn 1980, Fujio Masuoka invented a NOR-type flash memory :

** http://www.wikipedia.org/* http://rikunabi-next.yahoo.co.jp/tech/docs/ct_s03600.jsp?p=000500;

ü

××

NOR-Flash Writing and Erasing OperationWriting operation : Erasing operation :

* http://www.tdk.co.jp/techmag/knowledge/200705/index2.htm

potential voltage

Ground Positive Positive drain

potential voltageControl gate

Floating gate

Source

Insulating layer

Drain

NAND Flash MemoryIn 1986, Fujio Masuoka invented a NAND-type flash memory :

* http://www.wikipedia.org/

ü

ü

×

×

NAND-Flash Writing and Erasing OperationWriting operation : Erasing operation :

* http://www.tdk.co.jp/techmag/knowledge/200705/index2.htm

potential voltage

Ground Ground

Control gate

Floating gate

Source

Insulating layer

Drain

Ground

Positive

Ground

Positive

Positive

Reading Operation“0” state : “1” state :

* http://www.tdk.co.jp/techjournal_e/vol01_ssd/contents05.htm

Cells, Pages and BlocksFlash memory blocks :


Flash Memory IntegrationNOR or NAND ? :


Solid State Drive with Flash MemorySolid state drive (SSD) started to replace HDD :

pureSi introduced 2.5” 1-TB SDD in 2009 :

ü Data transfer speed at 300 MB/s

û Slow write speedFor example, a system with a units of 2kB for read / out and 256 kB for erase :in order to write 1 bit, the worst case scenario is

• 128 times read-out• 1 time flash erase• 128 times re-write


Fabrication of Flash Memory

* https://www.youtube.com/watch?v=M-wNC3Z3ZX4

HDD vs Flash MemoryDemand for flash memories : Price of flash memories :

* http://www.manifest-tech.com/ce_products/flash_revolution.htm

Flash Memory DevelopmentIntel flash memories :

• 130 nm (128 MB) in 2003• 90 nm (512 MB) in 2005

• 50 nm (1 GB) in 2007

• 34 nm (4 GB) in 2009

• 25 nm (8GB) :

http://www.pcper.com/reviews/Storage/Inside-Look-Intel-and-Micron-25nm-Flash-Memory-Production/Die-Shrinks-and-You* https://www.techinsights.com/blog/techinsights-memory-technology-update-iedm18

For Higher Recording Density ...Through Silicon Vias (TSV) : Stacked flash :

* http://www.semiconductorjapan.net/serial/lesson/13.html;

Samsung demonstrated 16 GB flash.

Toshiba also demonstrated 16 GB flash.

** http://www.intechopen.com/books/advances-in-solid-state-circuit-technologies/dimension-increase-in-metal-oxide-semiconductor-memories-and-transistors

Latest Flash Memory32 1-TB flash modules :

* https://news.samsung.com/global/samsung-electronics-begins-mass-production-of-industrys-largest-capacity-ssd-30-72tb-for-next-generation-enterprise-systems

V-NAND architecture : 16 layers of flash memories to achieve 512Gb

Latest Flash MemoryGrade 3 : -40ºC ~ 85ºCGrade 2 : -40ºC ~ 105ºC

compatible with 64 layers

* https://car.watch.impress.co.jp/docs/news/1148730.html

Bit Cost vs Recording CapacitySimple memory stack and BiCS memory :

* H. Aochi, R. Katsumata and Y. Fukuzumi, Toshiba Review 66(9), 16 (2011).

Memory capacity [bit]

Bit

cost

[arb

. uni

t]

Layers Simple memory stack

BiCS flash memory

Bit Cost Scalable (BiCS)BiCS memory design :

* H. Aochi, R. Katsumata and Y. Fukuzumi, Toshiba Review 66(9), 16 (2011).

String

Bit line

Upper selection gate

Control gate

Lower selection gate

Source line

Multiple-Valued Flash MemoryMultiple electrons can be stored in the floating gate :

* http://www.semiconductorjapan.net/serial/lesson/13.html

Conventional cells Multiple-valued cells

Mem

ory

cell

read

-out

thre

shol

d

Cell distributions Cell distributionsM

emor

y ce

ll re

ad-o

ut th

resh

old“1”

“0”

“11”

“00”

“01”

“10”

SONOSSi / SiO2 / SiN / SiO2 / poly-Si (SONOS) :

* http://www.eetimes.com/document.asp?doc_id=1279116

By replacing the poly-Si floating gate with SiN, i.e., Si9N10,

unbound dangling bonds can trap more electrons.

3-Dimensional Integration with Higher DensityMax Shulaker (MIT) proposed monolithic architecture : *

* https://sense.mit.edu/people/max-shulaker

Integration of Functionality3D monolithic can be advantageous over TSV etc. : *

* https://sense.mit.edu/people/max-shulaker

Flash Memory vs DRAMComparisons between flash memory and DRAM :

* http://pc.nikkeibp.co.jp/article/NPC/20061228/257976/

Flash memory

TransistorCondenser

Transistor

Tunnel barrier Floating gate

On OnElectrons are stored at the floating gate.

Electron charges are stored in the

condenser.

Leakage from the condenser.

Electrons cannot tunnel through the barriers.

Prin

cipl

esW

ritin

g op

erat

ion

Dat

a vo

latil

ity

Flash Memory vs HDD – ConfigurationsComparisons between flash memory and HDD : *

* https://www.enterprisestorageforum.com/storage-hardware/ssd-vs-hdd.html

Flash Memory vs HDD - PerformanceComparisons between flash memory and HDD : *

* https://www.enterprisestorageforum.com/storage-hardware/ssd-vs-hdd.html

information storage and spintronics 08ah566/lectures/info08_flash.pdf · department of electronic...

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