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Phase Change Memory Joint Project

LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

Hsiang-Lan LungMacronix International Co., LtdIBM/Macronix PCM Joint Project

Phase Change Memory: Replacement or Transformational

2 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012


PCM is the most advanced PCM is the most advanced emerging memory technologyemerging memory technology

Replacement?Replacement?

Transformational?Transformational?

ConclusionConclusion



The most advanced memory technologies in 2012 ISSCC

20nm 8Gb PCM 23nm 4Gb DRAM 20nm 64Gb MLC NAND

109.5 mm230.9 mm259.4 mm2

PCM density surpass DRAM in 2012 ISSCC

Source: Y. Choi et al, ISSCC 2012.



Breakthrough: Measure the thickness of amorphous region to overcome R-drift issue

Digital picture data retention Demonstration

MLC PCM is possible after a technology breakthrough

Source: G. Close et al, VLSI 2011.

MLC capability potentially makes PCM much denser than DRAM in the future



PCM is the most aggressive scaling emerging memory technology ever

YEAR

Chip Den

sity [M

bit]

Techno

logy Nod

e [nm]

Surpass DRAM density @2012

Surpass NOR density @2010



Current PCM position in memory technologies

NOR comparison: PCM has higher density, faster write speed, erase free and better scalability. NOR has better high temperature data retention.

DRAM comparison: PCM has higher density, better scalability, MLC ability and nonvolatile. DRAM has faster access speed, faster write speed and better cycling endurance.

NAND comparison: PCM has fast access speed, better cycling endurance, lower latency, erase free. NAND has higher density, lower programming current.



PCM is the most advanced PCM is the most advanced emerging memory technologyemerging memory technology






NOR Compatible 65nm 512Mb PCM in a Cell Phone

Source: EEtimes 2011.



PCM in Embedded Systems

Low Power MCU + PCM FPGA + PCM



Solder Bonding Issue

Screen PrintScreen PrintSolder PasteSolder Paste

Place Place ComponentsComponents

Dry PasteDry Paste Reflow Reflow SolderSolder

CleanClean TestTest

SMT process flow SMT soldering reflow oven

IC board after SMT soldering

Lead free Soldering temperature is 260ºC~265ºC.

Soldering reflow time is 30~40sec at the highest temperature.

Pre-coded PCM data may be lost after soldering.



DRAM Replacement by PCM?

DRAM Cell: 12ns capacitor charging time, 10uA capacitor charging current , 1E15 cycling Endurance

The closest PCM approaching:

30ns set speed 80uA reset current

Source: I.S. Kim et al, Symposium on VLSI Technology 2010.

1E11 cycling endurance



Faster

Slower

Resistance

+

-

Resistance

+

-

Materials engineering to increase the set speed

0.00 0.25 0.50 0.75 1.00

0.00

0.25

0.50

0.75

1.00 0.00

0.25

0.50

0.75

1.00

Recrystallization time (ns)

12.059.4107202296391486581675770

Sb2Te

3

GeTe Ge

Sb

Te

121

131151161

111212

275

268245

225

Source: H. Cheng et al, MRS Spring meeting 2010.

10ns set speed was demonstrated

Set Time (us)

Set Time (us)



Fully reset cell and low reset power to increase the cycling endurance

1M cycles10K cycles10 cyclesVirgin

Active region

Ge2Sb2Te5

Voids generating Voids gathering Voids block electrode

Volume expansion

Source: J. Chen et al, IMW 2009.

Source: I.S. Kim et al, Symposium on VLSI Technology 2010.



High power efficiency memory cell design to reduce the reset current

Source: J.I. Lee et al, Symposium on VLSI Technology 2007.

Thermal confined cell Thermal confined bottom heater

GST

Source: J.Wu et al, IEDM 2011.



NAND Flash is a moving target

Source: NAND data from Nikkei Electronics Asia Sept. 2009

NAND Manufacturing Technology

HK MG flat cell store more electrons

M1X MLC NAND

Source: J. Hwang et al., 2011 IEDM

Mature MLC solutions



16

PCM is the most advanced PCM is the most advanced

emerging memory technologyemerging memory technology






Smart phone, tablet and cloud computing is one of the icons of transformational technologies



PCM is trying to play an important rule in those transformations

costdensity

HL

LH

PCMPCM

SCIENCE VOL 332 P543 2011CNT Phase change material1~6nm



DRAM

512MB NAND

An Example of Smart Phone Memory System (HTC Desire)

NAND

Source: S. Kim et al, ACM SOSP Workshop 2011.



Capability of NAND Flash in a smart phone greatly affects the user experiences

WebBench AppInstall

Random write ability dominates the web browsing performances

Source: S. Kim et al, ACM SOSP Workshop 2011.



Source: V. Venkatesan, Flash Memory summit 2011.

Current Mobile Platform NAND Flash Performance vs. PCM Performance

PCM will great improves the user experience which is a key factor of a hot smart phone

NAND Flash performance requirements in current mobile platform



PCM Mobile Platform Memory System Transformation

Mobile RAM

NAND

PCM

Code storage, XIP code execution, Web browsing, swapping, boot, email, multitasking…RAM

Photo pictures, movies, …ROM

In place code execution, high performance, long battery life, instant ON and play, low cost single chip solution

All programs need to move to DRAM for execution.

Code

Photo MoviesData

Refresh

Slow access speed



http://en.wikipedia.org/wiki/File:IBM_Watson.PNG

The Story Behind IBM’s Watson

http://en.wikipedia.org/wiki/Watson_(computer)

Watson is made up of a cluster of ninety IBM Power 750 servers (plus additional I/O, network and cluster controller nodes in 10 racks) with a total of 2880 POWER7 processor cores and 16 Terabites of RAM. Each Power 750 server uses a 3.5 GHz POWER7 eight core processor, with four threads per core.

X 90

http://www-05.ibm.com/ch/presentations/power7/pdf/Serge_POWER7_config_03_02_2010.pdf

The IBM team provided Watson with millions of documents, including dictionaries, encyclopedias, and other reference material that it could use to build its knowledge. The content was stored in Watson's RAM for the game because data stored on hard drives are too slow to access.

50W 50W2MW



Power and cooling cost is higher than hardware cost



Getting worse in the future

Source of the numbers: R.F. Freitas et al, IBM J. RES. & DEV. VOL. 52 NUM. 4/5 2008

Critical applications are undergoing a paradigm shift



Memory-storage hierarchy needs a transformation: Storage Class Memory

Performance boosting: Store as many as possible data in RAM to avoid access slow SSD/HDD.

Power saving: Decrease the usage of power hungry rotating HDD and decrease the power of RAM.

PCM is the best candidate: Performance is similar to DRAM but has higher density. Use less chips (higher density) than DRAM and eliminates refresh (nonvolatile) to save power.

2015+RAM

PCM‐Storage Class Memory Disk Tape

Performance

Decrease the usage of DRAM and HDD to save power but keeping the same performance



How to keep at the same performance? a small DRAM buffer can make PCM having similar performance as DRAM

Source: Qureshi et al, ISCA 2009.



SCM Spec (data rate >1GB/s)

Assume Maximun Chip Current (8mA) 0.008 A

Assume Data block size (4KB) 32000 bit

Capacity 1TB

Write access time(Sec) 100ns 50ns 10ns

Reset Current(A) 10uA 20uA 100uA

I/O rate (IO/Sec) 244000 IO/s 244000 IO/s 244000 IO/s

Bandwidth(Byte/Sec) 976MB/s 976MB/s 976MB/s

PCM Storage-Class Memory Device Requirements

Relax than DRAM




25 MW TF solar power station

1 KW TF solar panel

Area

Power

DRAM + Disk PCM

Comparison: A computer system with 2 Giga Start I/O per second capability @ year 2020

23220 sq ft 12 sq ft

22 MW 1 KW




Cost Cost Cost!Cost reduction: MLC PCM

Measure the amorphous region thickness rather than resistance

Source: N. Papandreou et al, IEDM 2011.Source: D.H. Kang et al, Symposium on VLSI Technology 2008.

Resistance drift makes MLC PCM difficult



Cost Reduction: Polysilicon diode makes 3D stackable PCM possible

Source:S. Herner et al.,

Source: S. Lee et al, IEDM 2011.

Matrix 3D memory

Poly diode PCM



PCM is the most advanced PCM is the most advanced

emerging memory technologyemerging memory technology






Scaling is the key

SCIENCE VOL 332 P543 2011CNT Phase change material1~6nm

Source: Xiong et al, Science 2011.

Bit Lines

Word Lines

MemoryElement

Access Diode

Novel Diode Access4F2 Physical Cell Size

2b/cell, 4 Layers

Multiple bit storage per memory cell



Only the Paranoid Survive

Andrew Grove’s Only the Paranoid Survive describes 28 years of ups and downs at the famous computer chip manufacturer Intel.

Grove's central purpose is to explain how organizations can detect and respond to major changes in their industry. Such changes result from what Grove calls "10X" forces, such as the microprocessor, the "talking movie," Wal-Mart, and the breakup of AT&T. The major challenge of any organization, according to Grove, is to determine whether a new force for change is a "10X" factor or just "noise."



Thank you!

Phase Change Memory: Replacement or Transformationalleti.congres-scientifique.com/workshopmemories2012/31_Lung_2012... · IBM/Macronix PCM Joint Project Phase Change Memory: ... Phase

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