Phase Change Memory: Replacement or Transformational

Transcription

1 Phase Change Memory: Replacement or Transformational Hsiang-Lan Lung Macronix International Co., Ltd IBM/Macronix PCM Joint Project LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

2 PCM is the most advanced emerging memory technology Replacement? Transformational? Conclusion 2 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

3 The most advanced memory technologies in 2012 ISSCC 20nm 8Gb PCM 23nm 4Gb DRAM 20nm 64Gb MLC NAND 59.4 mm mm mm 2 PCM density surpass DRAM in 2012 ISSCC Source: Y. Choi et al, ISSCC LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

4 MLC PCM is possible after a technology breakthrough Breakthrough: Measure the thickness of amorphous region to overcome R-drift issue Digital picture data retention Demonstration MLC capability potentially makes PCM much denser than DRAM in the future Source: G. Close et al, VLSI LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

5 PCM is the most aggressive scaling emerging memory technology ever Surpass DRAM Chip Density [Mbit] Surpass NOR Technology Node [nm] YEAR 5 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

6 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. 6 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

7 PCM is the most advanced emerging memory technology Replacement? Transformational? Conclusion 7 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

8 NOR Compatible 65nm 512Mb PCM in a Cell Phone Source: EEtimes LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

9 PCM in Embedded Systems Low Power MCU + PCM FPGA + PCM 9 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

10 Solder Bonding Issue Phase Change Memory Joint Project SMT process flow SMT soldering reflow oven IC board after SMT soldering Screen Print Solder Paste Place Components Dry Paste Reflow Solder Clean Test 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. 10 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

11 DRAM Replacement by PCM? Phase Change Memory Joint Project DRAM Cell: 12ns capacitor charging time, 10uA capacitor charging current, 1E15 cycling Endurance The closest PCM approaching: 30ns set speed 80uA reset current 1E11 cycling endurance Source: I.S. Kim et al, Symposium on VLSI Technology LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

12 Materials engineering to increase the set speed Te Sb 2 Te Sb Recrystallization time (ns) GeTe Ge Slower Set Time (us) Faster Set Time (us) Resistance Resistance 10ns set speed was demonstrated Source: H. Cheng et al, MRS Spring meeting LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

13 Fully reset cell and low reset power to increase the cycling endurance Voids generating Voids gathering Voids block Active electrode region Ge 2 Sb 2 Te 5 Volume expansion Virgin Source: J. Chen et al, IMW cycles 10K cycles 1M cycles Source: I.S. Kim et al, Symposium on VLSI Technology LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

14 High power efficiency memory cell design to reduce the reset current Thermal confined cell Thermal confined bottom heater GST Source: J.I. Lee et al, Symposium on VLSI Technology Source: J.Wu et al, IEDM LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

15 NAND Flash is a moving target NAND Manufacturing Technology Phase Change Memory Joint Project HK MG flat cell store more electrons M1X MLC NAND Source: J. Hwang et al., 2011 IEDM Mature MLC solutions Source: NAND data from Nikkei Electronics Asia Sept LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

16 PCM is the most advanced emerging memory technology Replacement? Transformational? Conclusion LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

17 Smart phone, tablet and cloud computing is one of the icons of transformational technologies 17 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

18 PCM is trying to play an important rule in those transformations L H cost density PCM PCM H L CNT 1~6nm Phase change material SCIENCE VOL 332 P LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

19 An Example of Smart Phone Memory System (HTC Desire) 512MB NAND NAND DRAM Source: S. Kim et al, ACM SOSP Workshop LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

20 Capability of NAND Flash in a smart phone greatly affects the user experiences Random write ability dominates the web browsing performances WebBench AppInstall 20 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012 Source: S. Kim et al, ACM SOSP Workshop 2011.

21 Current Mobile Platform NAND Flash Performance vs. PCM Performance NAND Flash performance requirements in current mobile platform Source: V. Venkatesan, Flash Memory summit PCM will great improves the user experience which is a key factor of a hot smart phone 21 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

22 PCM Mobile Platform Memory System Transformation Refresh Mobile RAM Code PCM Code storage, XIP code execution, Web browsing, swapping, boot, , multitasking RAM Slow access speed NAND Photo Movies Data Photo pictures, movies, ROM All programs need to move to DRAM for execution. In place code execution, high performance, long battery life, instant ON and play, low cost single chip solution 22 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

23 The Story Behind IBM s Watson Phase Change Memory Joint Project 50W 2MW 50W 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 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 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

24 Power and cooling cost is higher than hardware cost 24 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

25 Getting worse in the future Phase Change Memory Joint Project Critical applications are undergoing a paradigm shift Source of the numbers: R.F. Freitas et al, IBM J. RES. & DEV. VOL. 52 NUM. 4/ LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

26 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. Decrease the usage of DRAM and HDD to save power but keeping the same performance R A M PCM Storage Class Memory Disk Tape Performance 26 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

27 How to keep at the same performance? a small DRAM buffer can make PCM having similar performance as DRAM Source: Qureshi et al, ISCA LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

28 PCM Storage-Class Memory Device Requirements Relax than DRAM Source of the numbers: R.F. Freitas et al, IBM J. RES. & DEV. VOL. 52 NUM. 4/ SCM Spec (data rate >1GB/s) Assume Maximun Chip Current (8mA) A Assume Data block size (4KB) bit Capacity 1TB Write access time(sec) 100ns 50ns 10ns Reset Current(A) 10uA 20uA 100uA I/O rate (IO/Sec) IO/s IO/s IO/s Bandwidth(Byte/Sec) 976MB/s 976MB/s 976MB/s 28 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

29 Comparison: A computer system with 2 Giga Start I/O per second year 2020 DRAM + Disk PCM sq ft 12 sq ft Area 22 MW 1 KW Power 25 MW TF solar power station 1 KW TF solar panel Source of the numbers: R.F. Freitas et al, IBM J. RES. & DEV. VOL. 52 NUM. 4/ LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

30 Cost Cost Cost! Cost reduction: MLC PCM Phase Change Memory Joint Project Resistance drift makes MLC PCM difficult Measure the amorphous region thickness rather than resistance Source: D.H. Kang et al, Symposium on VLSI Technology Source: N. Papandreou et al, IEDM LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

31 Cost Reduction: Polysilicon diode makes 3D stackable PCM possible Poly diode PCM Source: S. Lee et al, IEDM Matrix 3D memory Source:S. Herner et al., 31 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

32 PCM is the most advanced emerging memory technology Replacement? Transformational? Conclusion 32 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

33 Scaling is the key Phase Change Memory Joint Project Novel Diode Access 4F 2 Physical Cell Size 2b/cell, 4 Layers Bit Lines Memory Element Access Diode Word Lines CNT 1~6nm Phase change material SCIENCE VOL 332 P Multiple bit storage per memory cell Source: Xiong et al, Science LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

34 Only the Paranoid Survive Phase Change Memory Joint Project 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." 34 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012

35 Thank you! 35 LETI 4th Workshop on Inovative Memory Technologies 06/21/2012