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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…