NAND Flash Memory as Driver of Ubiquitous Portable...
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Transcript of NAND Flash Memory as Driver of Ubiquitous Portable...
July 17, 2010
NAND Flash Memory as Driver of
Ubiquitous Portable Storage and
Innovations
Jian ChenTechnical Executive, NAND System Engineering
aka: how we changed the world and the next chapter
2
Memory, Oh Memory
You never know when you are
making a memory
3
Outline
• History and Current Market Trend– Low Cost NAND Flash Enables Multi Mega Markets
• NAND and MLC(Multi_Level_Cell) NAND Basics– NAND Structure and Operations
– Technology Roadmap
• Challenges and Opportunities of Scaling– NAND Flash as Technology Driver
– What It Takes to Success in This Business
• Conclusions
4
World’s Early Solid State Non-Volatile Memories
荷馬史詩Homer's Iliad, Late 5th-early 6th B.C
Positives:
• Store Both Text and Images
• Great Data Retention
• Solid state, no moving parts
• Tools Simple and Low Cost
• Simple Process– CMP & “Dry Etch”
Negatives:
• High Cost, Not Portable
• Small Density and No “Mass” Market
• Slow Write Speed, Labor Intensive
• One Time Programmable
• No scaling for thousands of years
When there is civilization, there is need for non-volatile memory. Safest Job.
5
About SanDisk
▶ A Silicon Valley success story – founded in 1988, went public in 1995
▶ We only do Flash! We do Flash right.
▶ Vertically integrated: develop from bit cell to final systems to retail
▶ Famous for driving MLC, First MLC patent, first NAND MLC product
▶ Invented Compact Flash & co-developed SD/uSD etc industry standards
▶ Co-own two 300mm Mega Fabs with Toshiba, Announced Fab5 this week
▶ $3.6 Billion in revenue in 2009 with over 3,000 employees worldwide
▶ Major portion of business is OEM: SanDisk inside
▶ SanDisk SSD in 8 of the 10 top netbooks makers
▶ In some of the major SmartPhones
6
Then the Last 19 Years…
19912.5 inch20MB
35KB/sec$50/MB
201011x15x1mm
32GB20MB/sec~$2/GB
e.g. Space ShuttlesBoeing 777 Black Box
In Billions of People’s Pockets
25000X!
8Mbit
0.8um(~1991)16Mbit
0.5um
64Mbit/MLC0.5um(1995)
256Mbit/MLC0.28 um (1998)
8G/MLC70nm(2005)1G/MLC
0.16um(2001)2G/MLC
0.13um(2002)4G/MLC
90nm(2004)
16G/MLC56nm(2006)
32G/MLC43nm(2008)
64G/MLC32nm(2009)
64G/MLC2xnm(2010)
7
NAND Flash Market Forecast:
2008 Collapse, 2010+ Recovery
0
5
10
15
20
25
30
2005 2006 2007 2008 2009 2010 2011 2012 2013
CAGR 08-13
Petabytes 234.8 719.9 1,992 4,513 6,336 11,270 22,565 42,730 76,253 76.0%
Bit Growth 258% 207% 177% 127% 40% 78% 98% 90% 80%
Reve
nu
e
(Bil
lio
ns o
f D
olla
rs)
14.8%-14.8%
12.8%
21.9%
70.6%
25.8%
CAGR
08-13
ASP 1GB eqv. 52.1 19.1 7.94 2.99 2.40 1.65 1.03 0.61 0.35 -35.0%
ASP Change -52.3% -63.3% -58.5% -62.4% -19.7% -31.5% -37.2% -40.6% -43.3%
Source: Preliminary Gartner, November 2009
Semiconductor Forecast Worldwide--Forecast Database [SEQS-WW-DB-DATA]
NAND Revenue
12.4%
12.5%
1.2%
Pricing Could
be More
Conservative!
8
NAND Flash Demand Drivers: Mobile and SSD are Vital
Imaging Video & ComputingAudioDataThousands
of PB
19.9 PB
76,253 PB
Note: NAND flash consumption includes both in-system and removable storage such as flash cards.
Source: Gartner November, 2009
Semiconductor Forecast Worldwide--Forecast Database [SEQS-WW-DB-DATA]
Lifestyle Storage
Driver
Criteria
- Units (M)
- Capacity (GB)
- Portable
- Durable
- Power
- Performance
-
20,000
40,000
60,000
80,000
100,000
2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Digital Camera
Media Player
USB Drive
Camcorder
Mobile Phone
Gaming
Computing
Automotive
Other
9
The Most Exciting Time
iPhone/SmartPhones/Droids/Tablet
= New PC
Thin Is In, No HD
10
Flash Is Everywhere Already
In the next decade, it
will be BIGGER than
you think!
11
Huge Investment and Commitment: Not for the Faint of the Heart
Fab1
Fab2
Fab3
Fab4
Fab5
12
Outline
• History and Current Market Trend– Low Cost NAND Flash Enables Multi Mega Markets
• NAND and MLC(Multi_Level_Cell) NAND Basics– NAND Structure and Operations
– Technology Roadmap
• Challenges and Opportunities of Scaling– NAND Flash as Technology Driver
– What It Takes to Success in This Business
• Conclusions
13
Fundamental NAND Flash Cell
Operation
• Write and Erase by Fowler-Nordheim tunneling
– High write (program) and erase voltage needed, >20V
14
NAND Read Operation
Vread
Vcgrx (0V for Bin)
Vread
Vread
0V
WL0
WL1
WL2
WL30
WL29
WL31
SGD
WL31
SGS
SGD
CSL
BL0 BL1 BL3BL2
Blo
ck n
Floating
0V
Vread (5V)
Vread
Vread
Vread
• 8KByte bit-lines are read at a time.
•Block n is the selected block.
•WL1 is the selected wordline.
•Vread turns on all the un-selected
cells, regardless of its data.
•Read current flows through erased
(or data 1) cell.
15
NAND Program Operation
• 8KByte bit-lines are pgm at a time.
•Block n is the selected block.
•WL1 is the selected wordline.
•BL 2 is the program bitline
•BL 1 and 3 are program inhibited
•Example here is SB (Self-Boosting)
•Vpgm step up, so does Vpass
• Data=1 cells in WL1 is program
disturbed
• Data=1 cells on BL 2 is programmed
disturbed
• All other cells are Vpass disturbed
Vpass
Vpgm (~20V)
Vpass
0V
Vdd
WL0
WL1
WL2
WL30
WL29
WL31
SGD
WL15
SGS
SGD
CSL
BL0 BL1 BL3BL2
Blo
ck n
Floating
0V
Vdd
Vpass (9V)
Vpass
Vpass
Vdd Vdd0V
16
x416 levels
SLC2 levels
MLC4 levels
What Is MLC (Multi_Level_Cell) NAND
3 bits/cell8 levels
1
1
1
1
0
0
0
0
0
0
1
0
0 1
00 01 10 11
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
0
0
0
1
0
0
1
1
0
1
0
1
0
1
1
1
1
0
0
1
1
1
0
1
1
0
1
0
0
0
1
000 001 010 011 100 101 110 111Co
st
Go
es D
ow
n
Syste
m E
xp
ert
ise
Incre
asin
gly
Im
po
rtan
t
17
Key Attributes of NAND Flash MemoryMaking it the Driver of Ubiquitous Portable Storage Mega Markets
• Lowest Cost– Simplest cell structure
– Smallest cell with SA-STI (4F2), close to litho defined minimum
– 2F2 with 2bits MLC, 8 generations of volume production
– 3bits with even most cost down, 3 generations of product shipped
• Best Suitable for Portable Storage Media– No moving part
– Low power and high speed programming/erasing
– Single bit program slow (200us), but can program 32KB at same time
– High Reliability
– Best media to be managed by flexible system
The above attributes has enabled several growing Mega Markets
DSC, USB drives, MP3, Gaming, Digital Video, Hand Sets and Mobile Phone , SmartPhone, Tablet yet unknown applications.
18
Outline
• History and Current Market Trend– Low Cost NAND Flash Enables Multi Mega Markets
• NAND and MLC(Multi_Level_Cell) NAND Basics– NAND Structure and Operations
– Technology Roadmap
• Challenges and Opportunities of Scaling– NAND Flash as Technology Driver
– What It Takes to Success in This Business
• Conclusions
19
It’s Getting Harder: Heaven for Fun Loving Engineers
Getting Harder and Harder:
– Lagging lithography technology
– Coupling ratio and high program voltage
– Floating to Floating gate coupling with scaling
– Less and less e- in sub-30nm memories
– Vth fluctuation due to random telegraph signal with scaling
– Gate delays, new materials
– STI Fillings
– Contact: high AR ratio for etch, clean and fill
– IPD, tunnel oxide scaling
– Equipment variations
– $$$ equipments
– Test cost
– Random perf. requirements
– Sys. design for perf. and reliability
– …Innovations!
20
Flash Management Know-How Required
Self Monitoring &
reporting
S.M.A.R.T
Likelihood of Flash
Wear Depends on Use
Dynamic Wear-Leveling
Manufacturing/Accumulated
Bad Blocks
Bad-Block Management
Bit Flips
Error Detection/
Error Correction
Write/Erase
Cycles Limitation
Static
Wear-Leveling
Limited Data Retention
Active Data Refresh
Challenge increases as process shrinks
21
The building
blocks make
the difference!
Advantage of Vertical Integration
22
Conclusions
• Amazing Journey the Last 20 years For NVM and esp.
NAND Flash
• Low Cost MLC NAND Enabled Multi Mega Markets
• Crude Oil of the Mobile Information Age
• Yet Growing Challenges for NAND Scaling, for
System/Process/Device/Design/Test Engineers
• Vertical Integration Is the Best Approach
• NAND Is Everywhere
• Will BIGGER Than We Think
23
PersonalData Storage
Core
DigitalImaging
Shoot & Store™ Family
Blue Family
SanDisk Ultra® Family
SanDisk Extreme® Family
Best
Good
Better
MobilePhones
Memory Stick PRO Duo™
miniSD™
MMCmobile™
microSD™
iNAND™
DigitalAudio
Sansa® e100
SansaTM m200
SansaTM c100
SansaTMe200
Gaming
SD™
Memory StickPRO Duo™
Cruzer Crossfire™
Cruzer® Mini
Cruzer® Micro Skins
Cruzer® Titanium II
Cruzer® Micro II
Thank You! NAND Everywhere…