MICA (P) No: 114/09/2006 • a quarterly publication of Data Storage Institute • OCT - DEC 2006

Director’s Message irst and foremost, I'm very happy to share that DSI has bagged the National Technology Award (NTA) 2006. This is the third consecutive year that the DSI has done so. This year, the research breakthroughs by our motor team in advanced micro spindle motor technologies for new generation hard disk drives (HDD) clinched the honours. I congratulate the team for this excellent achievement.

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Back to the summary of our last quarter’s happenings, we are excited to witness another of our proprietary technologies realizing commercialization. DSI will launch a new product based on DSI’s Internet SCSI (iSCSI) Target Software Module with Symmatrix Pte Ltd. We are also happy to have in our midst a distinguished scientist who was also a former staff. Our coding and signal processing (CSP) group is pleased to be able to work with Professor Andrey Trofimov again on the development of advanced signal processing algorithms for ultra-high density perpendicular recording channels.

DSI’s Tiny Motors Wins NTA 2006 unparalleled cutting edge technologies in tiny motors for hard disk D SI’s drives (HDD) bagged the coveted National Technology Award (NTA) 2006.This achievement is DSI’s third consecutive win in the prestigious National Science and Technology Awards (NSTA) presented annually by the Agency for Science, Technology and Research (A*STAR). The winning team comprises Dr Bi Chao, Dr Jiang Quan and Dr Lin Song. This triumph recognizes their outstanding research in advanced micro spindle motor technologies for new generation hard disk drives (HDD).

In the last quarter, DSI played host to several students’ visits. 36 International Physics Olympiad Students were introduced to DSI’s research on hard disk drives technologies, optical and holographic storage. There were three other overseas student groups, namely from Texas A&M University, Delft University of Technology and students from Korea under the National University of Singapore (NUS)/Electrical and Computer Engineering (ECE) Outreach Program. It was a great opportunity for our researchers to be able to enthuse these students with our work.

In an era where computers play a pivotal role in our digital lifestyle, our need for even higher capacity, higher performing and smaller HDD is palpable. And where there is a HDD, there is a miniature motor.

I hope you will like all the articles we have put up in this issue. Warmest Regards Professor Chong Tow Chong Executive Director

(from left to right) Dr Lin Song, Senior Research Fellow, Dr Bi Chao, Research Scientist and Dr Jiang Quan, Senior Research Engineer.

What’s inside Page 1 Director’s Message DSI’s Tiny Motors Wins NTA 2006 Page 2 - 4 QoS Based Multimedia Storage Appliance Magnetics Read Head for Ultra-high Density Recording Recent Conferences/Seminars/ Workshops Participated in by our Staff

The team’s achievements include the following innovations: • • •

Page 5 DSI Hosted International Physics Olympiad Students Students Far & Near A New Network Storage Product from DSI’s Proprietary iSCSI Technology Minister of State's Visit to DSI Prof Trofimov, an Ex-Staff Returning as Visiting Scientist Page 6 Our Invited Speakers Upcoming Events

In such a context, the advances made in micro motor technologies research, in par ticular spindle motors are crucial. Spindle motors are required to be tiny, to be highly reliable in an uncontrolled environment, to be able to achieve high speeds and at low acoustic noise and vibration during spindle operation.

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Advanced drive technology which can reduce significantly the acoustic noise of modern spindle motors built on the pioneering identification of acoustic noise source in the spindle motor, High precision motor measurement technology that enabled the HDD industry to measure their motors with nanometer resolution and characterize the motors quickly and accurately, Unique bearing technology that enables high speed, low noise and low power consumption spindle motor, and Effective electromagnetic structures which can make the spindle motor be compact and high power density.

Dr Bi and his team members received the National Technology Award from Dr Vivian Balakrishnan, Minister for Community Development, Youth and Sports and 2nd Minister for Information, Communications and the Arts at the NSTA Dinner on 11 October 2006.

A research institute of the Agency for Science, Technology and Research (A*STAR)

02 Storage Unlimited

Editorial: QoS (quality of service) is an industry buzzword today but with different connotation. To a restaurateur, QoS would probably mean how well the customers are served by the restaurant staff. To a storage administrator, he would view QoS in terms of managing the complex storage network and the proper correlations between business requirements and storage systems. Today’s storage system has been labeled as “Best Effort Service” (BES) due to the limitation of understanding the QoS of incoming request. A QoS Based system is highly sought after in order to maximize the resource utilization of the storage subsystem.

QoS Based Multimedia Storage Appliance By Mr Law Sie Yong Network Storage Technology Division Introduction n general, requests to a storage subsystem have different servicing conditions. For example, a video streaming request packet would need to be served within a certain time frame. If this video streaming request is serviced late, the client will see a jitter in the playback. In contrast, normal file upload/download requires each request to be served without a timeframe. Therefore, these kind of requests can be re-ordered to serve later, while realtime sensitive requests such as video/audio streaming are given higher priority.

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This project aims to design and implement a QoS aware storage subsystem that knows how to differentiate real time requests from the non real time request and maximize the resource utilization of the storage subsystem. In addition, the block size of tradition file system is limited to 4Kbytes which is not suitable for today large size file transfer. Small block size incurs more disk seek delay, rotational delay and also the more overhead for disk access as large file access need to be breakdown into smaller block size access. With new file system that support bigger block size (> 4Kbytes), it will reduce the disk overhead tremendously, as only fewer requests need to be generated compared to tradition many smaller requests.

Resource manager Functions as an Admission Control that keeping track of used and available bandwidth before determines if the server can serve the incoming requests based on the QoS parameter of the request. Cache Manager Interval Caching algorithm couple with pre-fetching technique is used. An interval-based caching algorithm aims to retain blocks interval brought in by the preceding stream in the cache for the reuse of the following stream, and hence makes it possible to guarantee continuous delivery of video streams. Prefetching is a mechanism to preload data before they are referenced from slow storage devices (disks) to fast cache memory. File System New file system is modified based on EXT2 Linux file system. The objective is to have a file system that supports block size greater than 4Kbytes. Currently, Linux file system has two kinds of I/O access, DirectI/O, PAGED-I/O. File Applications today make use of PAGED I/O access by default. While each PAGE size is limited to 4Kbytes, therefore, large read/write access will have to be broken into smaller access as which result in high overhead and lower throughput. On the other hand, Direct I/O will allow the large amount of data read/write at one time, which has better throughput. Disk Scheduler Disk Scheduler is designed to use WFQ (Weigh Fait Queue) algorithm that handle multiple queues. Each queue has different QoS parameter associated with it. QoS parameter will be translated into WEIGH which is used to prioritize the queues. Each incoming request is inserted into a queue depend on the QoS parameters of the request. Request in the same queues will be executed based on the algorithm ELEVATOR as they have the same priority.

System Architecture

QoS Based Storage Subsystem Architecture A QoS based storage subsystem architecture is proposed in this project, which include new caching manager, resource manager, file system and also disk scheduler. Most of the system architecture design had been completed but still subjected to further debugging and implementation. Description of the four key modules are as follows:

Figure 1: System Architecture.

03 Storage Unlimited

Editorial: The current-in-plane (CIP) structure in the read sensor is approaching the maximum applicable areal density (100~200Gb/in2) due to the limitation of its gap length and sensitivity. With the areal density pushing towards 1Tb/in2 mark, current perpendicular-to-the plane (CPP) spin valve sensors with a track width down to 30-35nm are required. This requirement posts a great challenge for current patterning and alignment techniques in read head fabrication. Current lithography is facing issues relating to sub-50nm sensor fabrication. The technique is too tedious and timeconsuming with difficulties in controlling the alignment as well as to obtain the clean (sidewall-free) sensor cells in the ion milling & subsequent insulator deposition process.

Magnetics Read Head for Ultra-high Density Recording New Process for the Fabrication of Current Perpendicular to Plane Read Sensors By Dr Han Guchang Spintronics, Media and Interface Division Introduction agnetic read head is one of the most important components in hard disk drives. The read heads are used to read information stored in magnetic media. It is composed of a giant magnetoresistance (GMR) sensor for sensing the signal of magnets in media and two shields for prevention of interference from unread magnets.

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Tunnel magnetoresistive (TMR) read head in which current flows perpendicular to the film plane has been used in the commercial production for an areal density up to 300Gb/in2. Some of the challenges for TMR read heads towards the extremely high-density recording are the reduction of resistance-area product (RA) and high TMR ratio at low RA.

1) E-beam lithography has to be used to obtain sub-50nm feature size, which is very time-consuming. 2) The undercut for the state-of-the art self-alignment technique will become very difficult to control. 3) It is a challenge to obtain the clean (sidewall-free) sensor cells in the ion milling & subsequent insulator deposition process. Our research team has developed a new processing technique to overcome the above issues by using a feature size reduction process to get the sub-50nm feature size, which is beyond the limitation of our lithography technology. CPP sensors with the feature size down to 40nm have been fabricated by this method and have shown reasonable magnetoresistance characteristics.

size of the first mask reduces with etching time.The isotropic etching stops when the desired feature size is reached.

Figure 1: Process flow chart.

Novel Process Approach Alternatively, CPP spin valve (SV) sensor is thought to be the most promising candidate for the application of ultra-high recording density. The challenges in CPP SVs are high GMR ratios and high RA to provide sufficient signal to noise ratios (SNR) for bit errors. As the area density is pushing towards 1Tb/in2 zone, read sensors with sub-50nm track width will be required. In the read head fabrication, the sensor size, particularly track width has been reduced by lithographically scaling sensor feature size. However, current lithography is facing following issues for sub-50nm sensor fabrication:

Figure 1 shows the first hard mask layer (M1) is deposited on the sensor multilayer and the second hard mask (M2) is applied on the first hard mask layer. A thin photoresist (by photolithography) or ebeam resist (by e-beam lithography) is spun onto the second hard mask. A sensor cell pattern is formed by conventional lithography process as shown in Figure1 (a). The pattern is conver ted into the second hard mask layer by either reactively ion etch (RIE) or ion beam etch (IBE) process. The first hard mask will undergo an isotropic etching process. Due to the isotropic etch of the first mask, the feature

The second hard mask is etched away by reactively ion etch (RIE) or ion beam etch (IBE) process in Figure1 (d). The process in Figure 1 (d) can be generally omitted or combined with the subsequent process in Figure 1 (e). The sensor size is defined by IBE using the first hard mask. Since the feature size of the first hard mask has been reduced in the isotropic etching process, a much smaller sensor size can be obtained. After sensor cell is defined, a protecting insulation layer is deposited to avoid the sensor damages from the subsequent processes and the shunting by the top electrode. Common lithography is used to open a via hole on the top of the sensor.

04 Storage Unlimited

The hole should be at least smaller than the sensor size so that the sensor’s multilayer is not shortened by the top electrode. However, this process caused alignment issues.To overcome this problem, a thin flattening resist is coated. Since the sensor stack is smaller and higher than the other part, the thickness of resist on the top of the sensor stack is much thinner as shown in Figure 1 (g). Typically, the step height for the sensor stack can be reduced from 45nm (before resist coating) to 8nm (after resist coating). Next, an RIE or IBE process is performed to etch the protection layer on the top of the sensor stack. Due to large selectivity between the insulating material and the resist, only the protection material on top of the sensor is etched away. After that, the residual of the first hard mask on the top of the sensor will be etched away to open the sensor via hole without etching the protection insulation material surrounding the sensor. This process is realized through the material selection of the hard mask 1 and the protection layer so that they can be etched with extremely high selectivity with respect to each other. Other etch back process can also be used for the opening of the sensor via hole.

the isotropic etching process rather than the resolution of the lithography tools; 3) The sidewall and redeposition issues can be solved using this process for sub-50 nm features. Fabrication of sub-50nm CPP sensor As shown in Figure 2, our process produces a sub-50nm sensor cell from 100nm100nm square pattern obtained by e-beam lithography. The reduction of the feature size is clear from the comparison between Figure 2 (a) and (b). Figure 3 shows a typical magnetoresistance curve of a spin valve of about 40 x 440nm2. The composition of the samples is the following: Ta20/NiFe20/Ta10/NiFe2/IrMn8 /CoFe3/Ru0.8/CoFe2.5/Cu3/CoFe2/NiF e2/CoFe2/Ta5, where the numbers are the thickness in nanometer. The coercivity Hc increases from a few Oe of bulk value to about 100Oe of the sensor cell. From the jump of the resistance at point A, a MR ratio of about 0.34% is derived, which is reasonable if we take the contact resistance into account.

Conclusion A new process method for the fabrication of sub-50nm CPP sensors has been developed using a new feature size reduction processing technology. Using this approach, the feature size is no longer limited by the lithography technology. A feature size reduction from over 100nm to below 50nm has been demonstrated in the fabrication of CPP read sensors. Further reduction in the feature size is also possible.

Figure 3: The typical MR curve of a CPP sensor.

It should be pointed out that since the etch rate of the first hard mask can be very slow (in our experiment: 2nm/min), the sub-10nm feature size is still controllable. The advantages of above processing technology over current selfalignment lithography are as follows: 1) A high resolution can be achieved because it allows the use of a very thin resist; 2) A feature size down to 10 nm is achievable because it is controlled by

Figure 2: AFM image of a sensor cell before and after feature size reduction process.

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Recent Conferences/Seminars/Workshops Participated in by our Staff: IEEE-Nano 2006 17 – 20 Jul 2006, Cincinnati-Ohio, US

International Conference on Magnetism 2006 20 – 25 Aug 2006, Kyoto, Japan

28th International Conference on the Physics of Semiconductors (ICPS) 24 – 28 Jul 2006,Vienna, Austria

Asia Pacific Data Storage Conference 28 – 30 Aug 2006, Hsinchu, Taiwan

TBOC workshop 26 – 27 Jul; 2006, Seoul, Korea 11th CISD International Consortium Meeting 27 – 28 Jul 2006, Seoul, Korea The 17th Magnetic Recording Conference (TMRC 2006) 7 – 9 Aug 2006, Pittsburgh, USA

International Conference Advanced Laser Technologies 8 – 12 Sept 2006, Brasov, Romania Solid State Devices and Materials 12 – 15 Sept 2006,Yokohama, Japan 14th IEEE International Conference on Networks Conference 13 – 15 Sept 2006, Singapore

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DSI Hosted International Physics Olympiad Students

Students Far & Near played host to three overseas student D SIgroups in the month of July and August. 14 students from Texas A&M University visited DSI on 12 July 2006, where two of our researchers shared about their research work in “Magnetic Media and Manufacturing” and “Spintronics and its applications in HDD”. On 1 August 2006, DSI played host to four professors and 28 MSc students from Delft University of Technology, Netherlands. During the visit, they were introduced to DSI’s research on High-Speed, High storage Non-Volatile Memory as well as Magnetic Sensors.

Mr Soh Swee Hock, Manager of DSI’s Graduate Student Affairs office, addressing the students from the International Physics Olympiad delegation during the visit.

Another group of students that visited DSI was from Korea under the National University of Singapore (NUS)/Electrical and Computer Engineering (ECE) Outreach Program. The students were given a laboratory tour on 3 August 2006, followed by an introduction to DSI’s nanotechnology research, in particularly holographic storage and Phase Change Random Access Memory (PCRAM).

A New Network Storage Product from DSI’s Proprietary iSCSI Technology

Minister of State's Visit to DSI

t CommunicAsia 2006 in June 2006, DSI announced its collaboration with Symmatrix Pte Ltd (SYMMATRIX) to launch a new product based on DSI’s Internet SCSI (iSCSI) Target Software Module.

M of Trade and Industry visited DSI on 17

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iSCSI is an official standard ratified on 11 February 2003 by the Internet Engineering Task Force (IETF) that allows the use of the SCSI protocol over TCP/IP networks. This protocol allows users to connect and use SCSI or SCSI-based devices such as IDE, USB, and Fibre Channel over a network, as if they were directly and locally attached. An iSCSI Target module is required to establish itself as a storage server in order to accept connections from remote iSCSI Initiators. DSI’s iSCSI Target Software Module is capable of interfacing with the third party iSCSI Initiators and provides access to the standard storage stack such as the SCSI block device.

“We are very excited to witness another of our proprietar y technologies realizing commercialization,” said Prof Chong Tow Chong, Executive Director of DSI. “This collaboration not only showcases DSI’s compelling research capabilities in network storage but also validates our commitment towards exploiting new data storage innovations for the benefit of Singapore’s economy.”

r S Iswaran, Minister of State, Ministry

August 2006.

SYMMATRIX has licensed DSI’s iSCSI technology through Exploit Technologies Pte Ltd, the commercialization arm of A*STAR, and will be launched as a new Network Storage product line under the SYMMATRIX™ brand name, SYMMATRIX has plans to promote Storage Area Networks (SAN) and IP Storage through this strategic licensing. The state-of-the-art prototype was exhibited at CommunicAsia 2006 and has an overwhelming interest from industry players.

Mr S Iswaran accompanied by Prof Chong Tow Chong, DSI's Executive Director, during the lab tour.

Prof Trofimov, an Ex-Staff Returning as Visiting Scientist his quarter, DSI is pleased to have in our midst a distinguished scientist who was also a former staff. Professor Andrey Trofimov, currently an Associate Professor at St. Petersburg University of Aerospace Instruments, Russia, will be with DSI from April - September 2006. He will be working with the coding and signal processing (CSP) group on the development of advanced signal processing algorithms for ultra-high density perpendicular recording channels.

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The key objective of his stay is to develop an iterative receiver based on the microtrack and micromagnetic modeling of DSI 1Tb/In 2 head/media combination considering the effects of jitter, correlated channel noise, partial erasure, timing error, and constrained coding. During his stay at DSI, Prof Trofimov will also be giving a series of seminars and present his latest work on channel capacity computation and the

a posteriori probability decoding of linear block codes. Prof Trofimov was with DSI’s Mechatronics and Recording Channel (MRC) division till 2002. His research area includes area of coding and signal processing for wireless communication systems and magnetic recording systems. His expertise is in iterative decoding, code design, and channel capacity computation.

06 Storage Unlimited

Asia-Pacific Conference of Transducers and MicroNano Technology

OUR INVITED SPEAKERS

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he 3 Asia-Pacific Conference of Tr a n s d u c e r s a n d M i c r o - N a n o Technology (APCOT 2006) was held in Singapore from 25 - 28 June 2006.

Asia-Pacific Data Storage Conference (APDSC) 2006

International Conference on Advanced Laser Technologies 2006

2006 Asia-Pacific Data Storage Conference T he(APDSC) was held in Lakeshore Hotel, Hsinchu,

International Conferences on Advanced Laser T heTechnologies 2006 was held in Brasov, Romania

Taiwan from 28 - 30 August 2006. Senior Scientist, Dr Liu Bo was invited to give a talk on “Slider Technology Towards Highly Stable Head-Disk Interface”. Research Scientist, Dr Han Guchang served as session chair for “Nonvolatile Memories”.

Research Scientist, Dr Yang Jiaping, a member of the Conference Committee, was invited as session chair in the four-day conference. The biennial APCOT is one of the significant conferences for Asia-Pacific MEMS/Nanotech research community and industry. This year, the conference attracted around 300 participants from 21 countries including the Asia-Pacific region, Europe Union and the United State.

DSI’s paper “Temperature Dependence of Thermally Activated Ferromagnetic Resonance in Tunneling Magnetoresistive heads” received the best poster paper aw a r d a t t h e c o n fe r e n c e . T h e a u t h o r s of the paper comprises G. C. Han, B.Y. Zong, E. L. Tan, K. B. Li, B. Liu, Y.H Wu and S. N Mao.

Joint Conference on Micromehatronics for Information and Precision Equipment 2006

Joint Conference on Micromechatronics T hefor 2006 Information and Precision Equipment (MIPE 2006) was held in Santa Clara, California, USA from 21 to 23 June 2006. Dr Liu Bo and Dr Ong Eng Hong, both members of the organizing committee of this joint conference, served as organizing chairpersons of the tribology/headdisk interface sessions and HDD ser vo sessions respectively. Issues, challenges, and solutions for future high density and high performance information storage systems were among the major areas of focus of the conference. In fact, more than half of the papers presented were in the information storage field. In 2003, the Information Storage and Processing Systems (ISPS) under the division of the American Society of

Mechanical Engineers (ASME), and the Information, Intelligent, and Precision Machines (IIP) under the division of the Japanese Society of Mechanical Engineers Dr Liu Bo (left), Senior (JSME) held a joint Scientist and Dr Ong Eng conference called Hong, Research Scientist. Micromechatronics for Information and Precision Equipment (MIPE). This joint MIPE conference will be held every 3 years alternating between US and Japan. This year conference also include the the Symposium on Frontiers of Magnetic Hard Disk Drive Technology and Tribology (by the Tribology division of ASME).

from 8 – 12 September 2006.The conference focused on the recent developments and advances in laser technologies and its applications. Senior Scientist Prof Boris Lukiyanchuk, was invited to give a lecture on "Processing with lasers beyond the diffraction limit: Theoretical aspects". Prof Boris Lukiyanchuk In his lecture, Prof (right), Senior Scientist, DSI Lukiyanchuk gave a review on the different methods to overcome diffraction limit and reported the DSI results, related to the modeling of corresponding effects. He further discussed new ideas, related to different optical photonic and plasmonic elements, which use transparent and metallic par ticles, rigid apertures, waveguiding structures and polarization effects.

TBOC Workshop 2006 th

8 International TBOC Workshop was held T hein Seoul, Korea from 26 – 27 July 2006. Senior Scientist, Dr Shi Luping was invited to give a talk on “Research status of nano material and nano par ticle for storage”. His talk s u m m a r i ze d t h e recent progresses on nano-fabrication and nano-particle, and nano-phase change in DSI including Nano-PCRAM cell fabrication by combination of fs laser with NSOM, Laser Interference Lithography, Laser nano-imprinting, combination of pulsed laser with SPM tip and Nanopumping.

Magnetic Recording Conference (TMRC) 2006 th

17 Magnetic Recording Conference (TMRC T he2006) was held at Carnegie Mellon University,

for flying height below 3 nm which is required for Tera2 bit per square inch (Tb/in ) areal densities.

Pittsburgh, Pennsylvania, USA from 7 - 9 August 2006. Senior Scientist, Dr Liu Bo and Research Scientists, Dr Zheng Yuankai and Dr S.N. Piramanayagam were invited to speak at the conference. Dr Liu gave a talk on “Novel Slider Technology Towards Highly Stable Head-Disk Interface”. His talk showcased DSI’s latest achievement towards highly stable head-disk interface technology

Dr Zheng spoke on “Scalable Toggle Read Head Towards 2 Tb/in Areal Density” which introduced a toggle read sensor with performance of size scalable, high sensitivity, small gap length and simple process that meets the 2 requirement of the magnetic recording density of Tb/in Dr Piramanayagam gave a talk on “Novel Intermediate

Layers for High Density CoCrPt:Oxide Perpendicular Recording Media” which investigated the use of novel intermediate layers to solve some of the problems of CoCrPt-Oxide based recording media and reducing the grain size of the recording media. This year’s conference focused on perpendicular magnetic recording components, system integration and extendibility of magnetic recording technology 2 towards Tb/in areal densities and beyond.

** The list of Recent Conferences/ Seminars/ Workshops participated in by our staff can be found on page 4

Upcoming Events Date: 29 Nov - 1 Dec 2006

Programme: Asia-Pacific Magnetic Recording Conference

Details of programme are accurate at time of print. Interested parties are advised to check with DSI for any changes.

DSI Building, 5 Engineering Drive 1 (off Kent Ridge Crescent, NUS) Singapore 117608 Tel: 6874 6600 Fax: 6776 6527 Website: www.dsi.a-star.edu.sg

Venue: Orchard Hotel