Storage devices space for now and in the future': symposium ... · symposium : proceeding, Technische Universiteit Eindhoven, dinsdag 18 mei 2004 Citation for published version (APA):

Storage devices "space for now and in the future'":symposium : proceeding, Technische Universiteit Eindhoven,dinsdag 18 mei 2004Citation for published version (APA):Institute of Electrical and Electronics Engineers (IEEE). Student Branch Eindhoven (SBE) (2004). Storagedevices "space for now and in the future'": symposium : proceeding, Technische Universiteit Eindhoven, dinsdag18 mei 2004. Eindhoven: Technische Universiteit Eindhoven.

Document status and date:Published: 01/01/2004

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SYMPOSIUM

Storage Devices 'Space for now and in the future'

Dinsdag 18 mei 2004 Technische Universiteit Eindhoven

IEEE Student Branch Eindhoven

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Voorwoord

Inmiddels is het wei een aardige traditie dat de IEEE student branch Eindhoven een symposium organiseert. Dit jaar is er weer een nieuwe groep tweedejaarsstudenten bij elkaar gebracht om dit symposium op de rails te zetten. Sommige van ons met al enige ervaring met organiseren en anderen met minder ervaring. Toch denk ik dat we met en zonder deze ervaring iets goed hebben weten te organiseren en natuurlijk hebben we er zelf ook vele leuke momenten en een nodige bruikbare ervaring aan over gehouden.

In de eerste weken hebben we voor het symposium verschillende onderwerpen bekeken. Toch was er een duidelijke voorkeur v~~r het onderwerp 'moderne data opslag'. Dit onderwerp sprak het meest tot de verbeelding. Over andere onderwerpen was veelal weinig te vinden of ze waren niet geschikt voor een breed publiek. Modern omdat het onderwerp erg breed is en de nieuwste technieken toch het meest interessant zijn. De ondertitel kwam vrij snel boven drijven. Voor de titel hebben we het gewoon bij het onderwerp van dit symposium gehouden:

Storage Devices "Space for now and in the future"

Data opslag is de afgelopen jaren aileen maar groter geworden. Het wordt gebuikt alsof het niet op kan, toch is die groei van de opslagmedia een zeer serieus onderwerp voor vele bedrijven. Soms zijn er al technieken in ontwikkeling die pas na de opvolger van huidige technieken op de markt komen, aileen op die manier kan de enorme vraag naar meer opslag capaciteit opgevangen worden. Met al die groei in omvang moet ook de snelheid waarmee de data weggeschreven of gelezen kan worden mee groeien en ook daarin slaagt men.

Op het symposium zullen verschillende nieuwe technieken aan de orde komen, zowel technieken uit de nabije als uit de verre toekomst. Daarbij valt te denken aan DVD als tweede generatie optische opslag; de derde generatie, Blu-Ray, komt er al aan en ook is de vierde generatie al in ontwikkeling. Dan gaat het dus over een sprong van ruim 10 jaar de toekomst in. Ook zijn er ook nog steeds ontwikkelingen op het gebied van de magnetische opslag .. Dan niet aileen de bekende toepassingen zoals tape en harde schijven, maar er valt nu ook te denken aan bijvoorbeeld magnetisch RAM-geheugen. Zelfs op dit moment kan er al weer een nieuwe oplossing bedacht worden. Data opslag blijft een zeer dynamisch vakgebied.

Ik wens aile bezoekers een zeer leuke en leerzame dag toe. Laat je verbazen door de toekomst van data opslag!

Joep de Groot Voorzitter IEEE symposiumcommissie 2004

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Programma

09.00u

09.10u

09.15u

10.15u

Ontvangst met koffie en thee.

Welkomstwoord Ludo Tolhuizen (Philips)

Data Availability Solutions Ronald Vogelzang (Computer Associates)

Probe Recording Architecture Leon Abelmann (TU Twente)

11.15u Pauze

11.30u

13.00u

14.00u

15.00u

16.00u

17.00u

From DVD to Blu Ray Disc

Lunch

Alexander V. Padiy (Philips) & Sorin G.Stan (Philips)

Laser Beam Recorder Mastering Jan de Ruijter (Philips) of Optical Disks

Mram, the memory of the future?

Signal Processing and coding for two-dimensial optical storage

Afsluiting

Liesbet Lagae (IMEC)

Andre Immink (Philips)

Ludo Tolhuizen (Philips)

17.15u Borrel

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Inhoud

VoolWoord Joep de Groot

Programma

Inhoud

Biografie Dagvoorzitter Ludo Tolhuizen

Data Availability Solutions Biografie Ronald Vogelzang Presentatie

Probe Recording Architecture Biografie Leon Abelmann Presentatie

From DVD to Blu Ray Disc Biografie Alexander V. Padiy Biografie Sorin G. Stan Presentatie

Laser Beam Recorder Mastering of Optical Disks Biografie Jan de Ruijter Paper

Mram, the memory of the future? Biografie Uesbet Lagae Paper

Signal Processing and Coding for Two DOS Biografie Andre Immink Paper

Organisatie

Dankwoord

Sponsoren

Symposium Commissie 2004

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4

5

6

7

8 9

14 16

21 22 23

41 42

45 46

57 58

63

64

65

66

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Data Availability Solutions

• Explosive growth in data • Requirement for zero downtime

BrightSto'-® • Dynamic environment • Rapidly changing technologies • Limited network bandwidth

Data Availability Solutions

Ronald Vogelzang, Business Technologist

, ,,~W.{~ ~ll,mm

- Data protection for laptops, desktops, distributed servers, data centers and mainframes

- Benchmarked performance - Unlimited system scalability - Unmatched flexibility - Storage as part of enterprise

management ' • Data security provided

through integration with eTrust- security processes

• Application availability provided'through integration , w~h Unicenter" infrastructure management solutions

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• "Enterprise-level functionality" - Integrated eTrust™ Antivirus technology - Built-in, centralized and cross-platform management - Integrates with the rest the BrightStor family of storage

management solutions ' - Advanced command line functions - Widest range device support - Supports all storage topologies (DAS, NAS and SAN) - Widest platform support (Windows, Linux, NetWare

and UNIX)

Ease the ornation of File S)l'Slem Devices

"" "*,,,- t ~----~ -4e~i('~~~

.; Integration with BrightStor ARCserve Backup ....ifor Laptops & Desktops (Formerly BrightStor®

Mobile Backup) - Users can select BrightStor ARCserve Backup for

Laptops & Desktops servers in the BrightStor ARCserve Backup console and backup the users information to a tape using scheduled jobs

- Migrate data from BrightStor ARCserve Backup for Laptops & Desktops servers to tape .

• Requests for restoration of data that has been archived Initiates a BrightStor ARCserve Backup restore job

- Multiple jobs write to the same media simlJltaneously - Significanfimprovement in performance

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• Improved encryption. - The current encryption algoritf,1m has been replaced

with a stronger, internationallY recognized triple~DES 168-bit encryption algorithm.

• Job Preflight Check. - Allows the users to check and correct issues regarding

security. media availability. or netwOrk connection

• '.J

before • .runningthe backup job. .

lANIWAN/

·····1/··

I=vI'>h.,."",o. Premium Agent AC111·.onl"'·

- New features include: ~ Single Instance Storage (SIS) suPport;;: . • New data-transfer interface using push technoio~" • Multi-threading supporting multi·CPU machines;; • Document-Jevel backup and restore

- Storage group - Mailbol< - Folder

. - Documents . . .. ;;ff·i.

- Requires BrightStor<!!> ARCseni~Backup'Agent for Microsoft Exchqnge

- Suppcirtfor doCument-level backup and restore

-":' ,. ",,:: ..

.. Data 'is written' in CA Tape. Format to Disk • Configure via Device Configuration screen • Copy date from Disk To Tape via tapecopycom~anC!

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• Server file system'~for.°' " ArJofic;aU - WindoWs - Unux - NetWare - UNIX - Mac OS X

Open flies agenf

• Database .aQents: SOL

• Improves performance • File-by-File restore • 'Snapshot' for on-line

Image,,8aCl<ups • Particularly effective

with small files

• Windows only Ethernet Polnt-ln-'rime

Tape Library

Data Path ......................

• Local and Remote Disaster Recovery

• DR Bootable Tape Support

• DR Bootable CD Support

• Integration with Automated System Recovery, ASR (XP and .NET)

• Discover • Monitor

Operations • Administer

Policies

• Forecast • Networked

Storage • Single Point

of Management

RAID 0 :> Data striping across devices

:> Real-Time Mirroring

RAID 1 (Fault-Tolerance)

Improves performance

:> and provides RAID 5 Fault-Tolerance

• Collection • Reporting • Monitoring • Analysis • Alerting • Automation • Integration

The reality ...

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-13

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Probe Recording Architecture

Probe Recording Architecture

Leon Abelmann

Systems and Materials for Information storage

MESA + Research Institute

University of Twente

and Materials for Information

Problem 1: Data Density

IBM Millipede project

AI'ray Animation Pr·jnc.iple. Animation

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Hard disk

Solution 1: probes

C60 molecules (1 nm)

Jim 6imzewski et 01 (uda) website

Problem 2: Data rate

More Problem 2: Data rate limit

Armnation

3: Access time

·18M HOD AccesslSeek Time-Performance Increase

-7%AGR

.... _·i\ .. rIIoJ....,.,..I'·.I __ F r~ttlJ'lt-I~~

*~!t .i

-Solution 3: Decouple seek/read

Hard disk !J.SPAM

Empty

Full

Solution 2: Parallel heads

More Problem 3: Access time Innuence of latency

5D~;--~--;500!;;;--"'--""""~OOO;;-~--";o\500",~~--:d

Processor frequency (MHz)

Bonus: Form factor

IBM It-drive, nano-drive

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Bonus: Power consumption

o _ UIID l50D 2000 2511)

Data rate [kBitls]

Mlertl!l\UhornCGI~itlOnl!!i

World activities

Who Medium Write Reed Actuotor

IBM Polymer heated tip heated cantilever Voice-coil HP Phase-change e-beam induced current Electrostatic

(molecular) surface drive Samsung Ferro-electric E-field force Voice coil Hitachi Polymer cold tip deflection unknown LG Polymer heated tip piezoelectric unknown

eMU Magnetic B-field force/MR Electrostatic STM heating comb-drive

MESA Magnetic B-field force/MR Electrostatic stepper

Voice coil actuator

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Springs & actuators,

Nanodrive

'I cm

Combdrive actuator

A.nimuiion

pSPAM Shuffle motor

Multiple actuators: improved concurrency

Magnetic Force Mode

WRITE external field

1

Recording media

MR Probe Design

Read Wri~

Current Magneti.ation (Movi<)

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Magneto-resistance Mode

READ WRITE

Animatkm, Vidco

Write Experiments

MESA+ /iWalker

li~~t'J!J! 'iE~1~f=

a.""IW'''~ ';.Votolo'l;t:fPIJ'(lt

~.$IXJf.rlOlJDli''q\

.... 1lwl(,~W 7.klI'I'd!"""W !I.~~n .. i1.Nr~

external field

2D /lWalker Harmonica Drive

StoBots Mass and Solitary

• -. . •

• J ..............

'-r.r,:" ~ .. - .. ..

•

•

• .. .. •

StoC · Tile

DiscoMected array: improved storage capacity Mass access Solitary access

Stobot Access times Conclusion

100 MSyte file, 10 kHz per tip

1 mmls Mass. + 1 m!'l1/,$$o1 X

Probe recording iSllQt only about probes, also about architecture

1 ;~n\:-;;;: ~.~~t!> i' c,~·~ ~:'-;l Li

10 cm!.sMaS$ • 10 em!5 Sol 0 'nH'~"'fi. •

• Decreased access t 'me • Increased data rate • Decreased form factor

1 n\fs~1 i:. • Adaptive PQwer consumption

20

- 21 -

- 22-

From DVD to Blu Ray Disc

Outline

• ~~troductlon to optical disc systems

_." _L,~.jjjyo$oo;fo""'"""'"""'::."""""""".o<IIjt~I1_~l '1;11 !o"'_~".(;'_· ..... l~"""'<4J",jo,,,,,'f<¥"~'" ~

Optical Storage Solutions

• Read-only optical discs: o CD·OA, CD-ROM, Vidfoo CO, HoeD, DO-CO, ~. o DVQ·Yideo, OVO-ROM. OVD-Audio, OIVX (obsolete) (j SACO. HDIOYD-a o BD-ftOM, HO·OVO (reed-onlv)

• Write-once read-many (WORM) discs: o CD-R, ODoR. DVO·R, OVD+R, BO.R

• Rewrltable discs: o PD (obsolete). CD-RW, D[)..RW o DVD-RW. DVO+RW. DVD-RAM Q MvDlsc (obsolete, u BD-RE, HD-DVO (formerly ADD)

• Magneto-optical (MO) disks, Including MlnlDlsc (MO) • Magneto-optical tape (obsolete) • Optical memory cards

- 23 -

A Simplified Roadmap

·"''''{~_;l'l'iIIN_~)Il~~_~~''''''<i'' >I'fE ~,_, •• , ~~od!,_ tr..;,..,~,,, ,""~ . ..,.,, .Mo¥ HI._

Preliminary Clarification

DVD and 80 eonverrtions.: 1 gigabyte (GBI =1000 megabyt •• (MB)

. = 1000'· kilobytes (1<B) Iff 10003 bytes

Computer industry convontions (HOD, &Ie,), Including CO slorago: 1 gigobyt. (GBI c 1024 megabytes (MB)

a 1024' klk>byte. (kel c1024"S bytes

.t!2!!.:. To .YOid the conlusion with the metric multiples, the International e .. ctrowehnlcal Commission lIie) inb"OdUC4ld in 1999 IMo preflAes "lIibfM (IIi), "'Mebl~ (Mil, and "Glbt H (GIl. tCI desi9'"lItll the mutdples 21G. 2., and ~ ofthe byte, but dMy .... YIIfY .eldom UM<f.

UniHS spec.lfied, prefil(e5 adopted lhtoughout this presemarion can'or"" 10 Ihe DVtl and BD .t.andMds..

~<.:""";c$r""(!";'I>"''''':'''' •• ,"",I.· .. \ .. .t.,.. .. _'''''6i'j6':~",," __ l ;F.,·[~,t,",,_U-_""T«,,".,.,IIII'_~!',lW.o

Optical Disc Market - CD and DVD Data Drives

0' 1999 2000 2001 2002 2000 2004 ms :z...XJ6

y.", ".""r;. j<.o:l""~~I"Io«N:"'_·"'~).\.~_"":·_f'>Io:!:f'<:_<to.j frIlf ~~~":"d~H·." .. _:,<>jl_I<>;N-8IotrH ~

Optical Disc Utilization

lnform.ation .exchange uxt sound so-ftware graphic," attimaticn viciec I'hoto. etc,

entertainment sales- &. ser'lh::Q comp1JtMOEM fln2n~

publishing, etc,

""'""::. ....... ~~~ ... """""', ... ,~ ... ".""-',..""'$."""'"..I4o .... ""! !l.a .."~."",,, h"'_II"', .. >I:.~'~ ,>" • ...,-.;,-·,.o><~. i')$<

Outline

• DVD systems o Inteme:hc'mef 5tartdcu'da.

t;NI;:., ....,."'t.;::t..~",_ ......... ~iltll,_,'~!I'"IIlr<"_ .. ""i :f;R~"'<f".". ...... I ___ " ... lr..o,.,..""'';;I",.'''''''''''''_*''''~~ )(0),0.

AppnC$th.7!1S 1if"ierenCCl mate:rtai mU9tc:tttJes sak1!!l & ma.rk~ttng coMput:e-r !f;ofa,yftn gam .. maries;. etc.,

DVD Standards - Current Classification (b)

"""" ~ '-\.r. ;P;-I~~~ "',,'<--"'...,Q'<!. ..... ..-, -,.I!"".!>t ~.", ..... ! >f~r 'l,-"1':"""" f:oool: ",""" "." .... ~: fT.<:""!b,; •.• "'~~'.'-l·~

OVO Forma\:s endorSed by

Royal Philips E~etronlc. and Sony Corp,

or by the OVO.RW Alliance backlKl by the Be Grnl.lp:

Hew.ett~Packard Company Mttsublshi Chemic:.al corp. Royal Philips Electronics Rlcoh Co., Ltd, Sony Corp, Yamaha Corp. Thomson M1J'tlm~ Dell Computer Corporation

- 24-

Optical Discs: Advantages vs. Disadvantages

• Advantages: :...J accepted worldwide standardization

;:.J removability combined with hlgh<ap.actty data storage "-I durability (~I!IS aettsltlVa to cHmate eh.anges) ;;J good: readout eYen when the ~18C surface contains c:tefec:ts :.:J no degradation during playback o cheap disc repHcatJon

• Disadvantages: :.:J relative complnlty of opdcs and servo electrottlcs ,not actual attymoreJ :J relat1ve1y Jow performance when compared with HODs o high-eapaclty rewrltable solutions ar. sUN expensive

"""",:. -""I","'"", __ ",,'IU<:""".~& __ ~_'!'!I~~"~"!

!fU..,:~..., ~~_(!"'''''' •• Y'H r..,,, ...... J~_ ...... 1e.~(

DVD Standards - Current Classification (a)

""'''''''''''''',l' 1>1;"" k'''''''''''''' .... ~~./Ilo'''' ... .$Hl>'''''''p~' ..... _rH ~H ..... __ • 1""'~·,...-');, ... .....oIt.rT'" ... "' .. >II'! •• w..,.~~ »H><.

Outline

• DVD systems ",'i,r:;'

o DTives Gild iIIflgln6s _ III'chiteClfurai Overview

<!<>C~,~. 'Iuo.::p1>i .'> !Ioo*""><i_) ~ (" ~ ... "",, "ed" ~'"'''''' ~ ..... ~~) ot:~f ~r"P',.!c,.". (I<O'I!:_II<d.",,,,,,,,,·T""·~_ ... ··lI->r ,,- m<.

Dve Formats Imdon.ed by the Dve forum

~

I ,.

12

The DVD System

..... """.-~".".. ...... ~.E, ...... ,.. .. -~l!~...,.,""JI! :f££'h""""""':,~;...:1!"..... .. "',... .. ~,~ h<, .... .."" .. _IN, t~. i'lI<J.<

Optical Disc Engine - A Simplified Block Diagram

~.; _,:::."",-.~~_...,.,.~~t:"''''.'''''''''V""",,"I!_=>-l £:;:t"'_'t' ... ~,t_; .. _",,,.¥r""_$'!"~IIII;<y)ll :ok

Basic layered Structure of Optical Discs

,.

25 -

A Functional Drive Partitioning

...,..,.tl_~~_J''''''_~M'''''''''/lipIooII.--<~! f1~~~"",'_.~",,",_t_>~Y'''I'''''_J, .. '''' •• ILl:I3.

Outline

• DVD systems !;':«n;"~"A:0l :,,;,,,,<1:.<>;<):

DVD layer Structure (1)

Cr08$ section illlOng the recorded track of a .tngle~ skit, slngte-layef DVD

CI'OM .. etlon along the recorded: tract:. of III doubie:&ldt!.lIlngle-iayer DVD

'""''''t;''''''ll'b'''''.~~8\lSfr-"_''~~.,*,,,-;', irt~"*""",""""-~l<-""lI<oI ... >~~"1T,,,,·_-III.rf"'1...~ "

DVD layer Structure (2)

Cross &eetton ~jOn9 the recorded track 01 a stngje~ sltl«. doUbie .... ayer OVl)

Cross aeetlon along the recorded treek of a doubleside. double-layer PVp

CD versus DVD (2)

SEN! photograph", cO and OVD sutmr~. M 5een from the: Inskie- of the dlse.

CD versus DVD Physical Parameters (1)

.,.l;;:;hM?'W<·~~"~"'~-'~""';!iI 1t;r\"''l'''"-''!:...f"""",''''''"",\io.4t'''~_Ik>-",tM1

- 26-

CD versus DVD

~~ ~.~f1I>!I"-._ ...... \,,c.""'''''''''''~~~!I_ .. ,,,, .. ';(f.~f"_""'.'fiI_U,,, ..... ,.,..,<t.-,,,,,,,_,,,.~,,,-~

Generic DVD Readout

• ~dl. ar .... ad out using ~ far.field diffraction of a 1M"," beam • Tho r_od beam has the amplitude and phase modified by !be

relief structure impressed on disc

CD versus DVD Physical Parameters (2)

k;<"{,"""I"'h>1r.>""'r~t __ ~~"""""'dt, :f>!!~,<'I't_,_"""'·_·¥Y'''l1~f·IiI#y'>l.?:fI·

,.

The DVD Laser Spot

R = 0.61). An,

Patameter Dependency Spo161ze at fOcus .{·'NA

""",,,_~,,,,,,,,,... ... :IWt"J,,,._,-"~""""t!.l if~/:s,,,,,,,_tf~'"""""':""'_"'f,~I'''''"''''''''~JiI.w>a .....

Diffraction Gratings

P -'lM.I'kIbI*Of'C!/t'gpel1OO ~gOl'f1beplrllmdtl!tgthI

ft'I_dlfluc~!I)I"de'r

). - teerWGYtolef'lgUt ft-fmOlt'ct~~I!ff«!lfdordllr

sin 19" -sin rl', mA p

Outline

"""..,("_~"'-""t",~:~~~(c.~,,",,,~ ... ,z,.J If)i# '''~'_ "".~""'",,\I.>lt""'''''~'' h''''1~l'''''" .... ~ \to ~t

Modulation Transfer Function (MTF)

DVD QPtIcaI cut-o\ffAquency:

J> 2· ~A = 1.846 ","-1 II.

;; ~ 2>', . NA .. 6,443 MHz 1

No""allzed spatloI fAquency.

.1..r=_A_ l"NA

Generic Optics for CO/DVD Readout (and Recording) RF Signal Generation

• Commot'! photo~ for CD and DVD , ...... • Objectiw len. dNlgn8d to woril with

1.2w and6.6-mm substnle ~ .e~a'lftth&{j~

laaer are posMbfe

• CDJJ)VO idStN' ~ tor tHdout:: 5-.1 "'W • Laser power fM CO I'eCOfdIng:

up to Z$O mW !52XC~

• 1,.ti.$«p-(rfHrtor OVD reeonUng; upto280mW (16XOVO)

- 27-

:kAb(' _'(I'M'" """ __ ~" __ .. """,,,,,,;!\.dh"_.;~J .w:t~~~", "",_~ ...... ,"'h""",,",\1( ~'\4.\*

~ntnd ilpertuf~ FaF ~g'\I.ll: c.o.cA ... e ... c+o

The Servo Channel

""""::'v~I'I~~*~~"""""'"_"'cl\; t":r.'tt __ .f.iu1!_~>"'>"rdl'>o\~<,".la_

Focusing of the Laser Spot

Maximum allowed focus error: ± (;:.9 tlM

Tracking the Continuous Data Spiral

JO.#1" ..... ~'!"'<i!0~'l\ .. ""~t ..... """",....,ii~~«.: ltH:tr~;_,'"""'_~"">"~41'f;.<'~'.l!M{¢t,_

~.<."11'l!'J1O?<:i'm."Ure 1""l't.z:lI'!rV<>"1!;'drzwKYJP='I'1

® Fic;ttvcc..tJn!i<1lJ~ i-M;O', LJ]

~tJ;;. Track pitch: O.74~m Maximum aliowiK! tracking error: t 6.1 j.tn'/

- 28-

Generic Electromechanics and Servo Functions

• I,.oedhmloed dia.c itr~y Motor) • pj.~ fotaliol'l tlUm'labl1!l motor)

• Adjust diu till jom), ~ In reoo~ avo ~/M. not Show,. on flGuAYj • Keep IeHr $polll\ foctH. tto- .actllf!1f.1t;

• TrltCking (firM dts.pktcementS 01 the ~*Wr f~~'" by Mlan "iMlJ" *Ui1») • sa.« l1et .. di .. pIeCoflMnta of the $IM!~ ended with track; fliC4lii*itWm periom'tM by the _l

"'-"0_l"'W""'!'-.~;.~_~~~! il';(Ii~~ ~--.. __ ,,;!~.1ioq""1:0#

Astigmatic Focus Method

_"'$<"'f'Wl:FI~¢a~",,*!if'Id1>o"'-'-'l !Mjj'~r~"...,.._...,." .. T" __ ~l[.~

Focus and Tracking Servo Loops

X.,f.) - ntt.r.nee po.ffion Oft di~ to b& ~Iowed by tM .er;ap<rt Xl{Gl - spot poslti(m, dewmlned by tM d'-pktC*fl\ent of h ~ lens ~s} _n~ureme;nt noise <It.} _dtsturbBl'le&fJ wiglneting irlH:fe 85 \WIt1., ~ b antmI loop $($,} _~tlY~.ll'or5igno1 ffoeuluaekln9~

Opon-looptr ... ""tun<:tlon: H(s) = G,(;;)K(s)G,(S)H,,,(s)

.;...-(, _,(I'fIi_ ...... _~ ... ;~"'~?""""!I"> ...... ~~,.j mJ't,.p"",,,",,,,, (_!'""''''''''''l''''~ .. j,.'''''V' , ..... <t._

CLY VS. CAY Speed Profiles

3t!'M<!.c4fSO I:il5cred~!I\'IrnJ

DIS!: _nallre_ney vo. disc ,ad .... In 6.6l< O~ V nnd 16X· ..... CAY systems

Unur velO<:ity and overspe-ect at the readout pol.t ¥s. dlse radius in e.sx C~V and 16X..".,. OAV.pl"",.

Idealized Signals Recorded on Disc

• NRZl- nootelurn to i!etO lnvened • The digitized RF signal I. contained In the continuous

pltll.no relief slructtlre on disc • PII (land) lengths are lilted to discrete values between 3T and

lIT (given by the mOdulalion code)

• T corresponds to the channel clock. wflich determines Ihe position In tlrn<' of each recorded bit

Readout Overs peed (X·Factor)

• The bit sequence Is recorded at a r ..... rence con.lanilinear velocity ,CL.V) v. = 3.46 ••• 3.52 ml$ (v." 3.$1 ••• 3.87 mI. lor the Inner layer 01 dual·layer media)

• The overspeed Ii Is defined as Ihe ratio between the linear velocItY of the readout polnl and the r ..... rence velocItY of the recorded <lata;

N=..!.. VO

• When Ihe dlst Is; spinning at constant linear velocity (C~ VI. the overspeed N Is equal to the X·factor printed on the drive package

• Audio CD players spin the disc at IX (I.e., N = 1)

••

- 29-

Speed Limitations

a Ov.rapMd ffmftf deWmlned by Pf'&PI'~.lf'lg MndWidm$ end me 1lpMd ofth6 ch.", ... 1 dtooorkr oncIl:wtck"ft\d dina pril

0: Angubrlr ffeql.ff:Jl(lV limim decermlnad by the Set'¥O eku;'t:ronias bandwidth tlnd by tI'MI powtf dU.aipoltion in me motor loop

':"""{,~~l~/!i*""""""Pod~jI'!l>'l!>._<rj ~,H)o_",_.~_."."'r",,,''''''''~·'''''' a:,_

Outline

Spectral Distribution of RF Components

RF Distortion Sources

• Length variations of the slmllar-l@l'lglh pits (lands) • Defocusing ot the I ..... r spo! • Optical dis!onlonslcoma, astigmalism, etc.) • ead track following • Incorrect poslttonlng 01 the photodetectors • Non·llat delay characteristics 01 the lront..,nd electronics

(analog preprocessing) • Limited bandWidth 01 the Iront..,nd electronics • Crosstalk tram neighboring electronic circuitry • In5uffici~nt re-solutlon 01 tt\EI analos .. to dlsitat conversion, etc.

A Generic Read Channel (2)

~:., ,.....lI,:;;;.,.;$«~"''''''''\.I.~".,.,.,#~~j!.'''''\o't:t)

';;'1 """",_I.""""~""J'_~"'"""""""",,~~~ 1'Ih

DVD RF Signal

;:;.., .. :> _·?'hI!Ir'''''''''~<!A ___ ''I>:ltt(!'f<~'''''''I!,.;q lrJ'f ~'f"" hM''''''''''·U ..... ~,,!l:v __ ~ .• J'',>. :11"",

DVD RFelgnal as read out from disc

By ~ntrastwlth cDsystenl&, eqlJal:ivrtkmof the readout Rf s{gnatls neceesaryl

- 30

A Generic Read Channel (1)

Channel decoder functtons: u lmptovn RF slgnal quallty before: dat¥: d!ttect1On :I regenerates emb9dded enann,,1 dock ;J r'e¢Oft9tn.ieta o~n.' <tabl 8)IMbobJ :l ntgener.tes raw bit W.aM from .nato; RF .'9na! o de\$ets and torr~1S >ftrr0f8 ~ng in tn" rD9"nefAted data stream

"""""'''''''''l'W<"~~;I.''i.j,,'''_~'''''''~''''''''''''' .:'fff,p<p=,_.~W_I. .......... ..!t"",,......p'*,",UI,_

Channel Equalization

Equalizer tasks; a compensllM'lII&>mmslc~~ofU.~~

tI~lnt!:!I~tntatf«WIl:.)

Q ~.lgnIIl~f~($NRI

U(.IQrtJdy~~~~M$Q~

_ .. , ...... ~s-,;;..-.4i_j'<47~~ :£il(~~,..-_~vft .. ""_Y'!,,~,~~_

RF Signal Equalization

..,. .. t, _(?N:~"~'~lS_""'htllrll"~~";"

.trr.1It:..,:",~.." ~_ ... _ t ....... IlifJ"ir ... '''~",»'- li->-I ,,.,_

Hot«-: The pIDbt:i curves are for a ax OVO system.

..

...

Data Slicing

ThrMhold detector talfe~r}

....... ,~ __ "'tI.''"_"..,,., ... A' ......... ,'~p''~ .. H ........ '~ ~',1""Jii'_~'"'~"~v1\ ___ 1!.<l~1"~

Defects on Disc

Delects: o Hbtack dots'" (regKms wtlh zero-reflectk)n ~evat$} tJ fin".r Prints (f89iOn$ with strong RF amplitude dlstoniOtl'$)

trmtrruptlon In Informat$on layer (regions wtth land retl~ l.w'tt) u ecratches (str.ong fitF am~ and phase dlStol'tlon1lt

""",fi.~~~''''-''''''j~''''''~"'''~'~_''' 1Iia"-'''''''''''''i""*-~"",,.-I-I'''~~'''''_'' HI'<

Improving Data Regeneration (2)

Error detection and eorreetlon by adding redundant Information (e.g. p3l1ty-check Information)

Rule: Add "l"lf the number of ones In a row (eolumn) is even; add "0" otherwise.

..

- 31 -

§I 4-- ,A"dS Mill Clock Recovery

II1II L,"~.~ .. J--::----L: .' .. m<J·::'.-L.~., .. r~F I n _ .. ~ FlJ1JlnmU1Jlrtll.llJU1JUUUUUUU1.rJlfstr JlJ1J1.fll1flJ'~

UllUlmllllllUlIIllllllllllllllJl. ... "", ... _"'toi~"_,,,,*,,,,~)IfI: .... _\'.¥f»JIt'~~) lli:;tf#,._!~ .... \¢I<IOII!«f.v.l.r""""W~_l{,eu


Input data: Any advanced technology 1$ Indistinguishable from magic. (Arthur C. Clarke)

Input data -output data 1

Anhltamncnslb yeo nlm dllge. ..

lo:"'4"""~~,,,,'-,"'dl"''''''i''.l'''''' __ ~~_dIo\ It/tl~"'bll!w_U;,,,· ... ,,,,O'I-I,,,-<.v;·-'''i~_


Error detection and correction 01 received data

D D -Erroneously received

Parity Ms correctly Indicating an error Parity bH$ Incorrectly Indicating no error!

......... ~··_;:",,110"'-_""" ... ·;,,_~~_~~ Ofl:I·~_",;~_~~) ... t_"""'.Iit<y...,.~

Data lnll>ne"ving

5 •


Channe.1 modulation

Clock recovery becomes Impossible without modulating tile raw bit sequencel

~r----------------~l _____ ~' ---

" .. '"'''' ..... h?>'<~ ............ .,J~ ... .,.!.<\..........-~,,"'-"v>_"'~'I! !t'~J: ~~~>:_:.b ... : .......... : Uo:_"'vd l~"",,>10<;,·· ..... :~.r'"

DVD Error Correction Capacity

• Straightforward error detection end correction ::J Inner code IC1, '"horlzontally"l: max. 5 bytes a Outer code (C2, "vertically"): max. 8 bytes

• Erasure-based error detection end correction :..J Inner code lei, Nhortzontalty"): max. 5 bytes o Outereode rC2, "vertically"': max. 16 byte'S

Practical error correction capacity: j tl'la"lnnun burst errors of 1.83 data seeto~

...l 6.35 mm (!of traeil. kcngth

_", _.i'lf:l~:,. ""~_)1i""-""~11it.t.""""""""""~1'~_.:.j ~::1 "I.>I'.,.." .... !~,"_l!-.-..sT ... _*'_..".H ~

Outline

• Recordable and rewrltable eve systems u OvervMJw 01 W(itl)-<)l'Ict1l11'1d phasliI-<:hang-f< media

~'r

,.

- 32-

DVD Inner and Outer Reed-Solomon Codes

6yte-onentf:ci ECC bloek size: 172 + 10.182 columns {of bytes) it! • 12 ... 16" 2'08 rows (of bytes)

...... "'::._lI't>i<l:t .......... """"_)4"" .. _?""._1/j>~fI_ ... "~1 lIolf ~.:Oq><._.~_:_t_."Y,,;l"':"'..,,;, ·""...,.l8. No<

AudioNideo Features

• DVD-Video media contain digitized video streams encoded In MPEG~2 format (variable compression)

• High-quality (betW than VHS) • Maximum data rate at 1X readout: 10.08 Mbls • Video playback time: 2'1", hours (at average MPEG-2 compression rate) • Support for slandard (4:3) and widescreen (16:9) TV aspect ratio. • Multiple surround audio tracks (up to eight). which Includes support

for language selection • Subtitle and karaoke features • Seamless branching and support for menu-driven video playback

(InteractiVlty) • Parental lock mechanism • Supported audio standards:

::I MF'EG-2 allOlo (5.1 and r.1 audiO channels) o Dolby Digital (AC·3, 5.1 8udig c.hann.ls) o LiMe.t PuIs. Code Modulation (L.PCM, 16-, 2D-. end 24·bit aMreo) :. Digital Theater !ktt.md (DTSl- op'iiOf'liftI :. &ony Oyrwunic Dl,gtt.al Sound (SODI) - optional

",""","'&I:"li·l>IijIo·.,:.,:",,,,, ... ~":IiI ...... _n<lol!!)lIl'f""_~') :.t::l:,..._f<n:I><: ..... t"""'...."., •• rr.· ... "'-'1II'·"""I~·'.l1I' ..

Media Overview

• Recordable optical discs o CO·R, DO-R o DVO-R, DVD+R

• Rewrltable optical discs o Pha8e-ehange Dual (PO) o CD-RW, OD-RW ]) OVD-RW ]) OVD+RW ]) OVo.-RAM

• Materials ~ Organic dyes1otwMte-ont:1t d18~ (used In CD~R. OVD~R.,.,} ::.: Phase-changlt aUQye 1tJt t't'wrltable discs

_ Ag-In-Sb-Te iu~ed!{j CO.Jl:W, DO-RW. DVD·RW, DV(I.RWI _ Gf,.St'l·TIiI (t.itll!l~f in DVO~F!.AM{

_0: (; _ .. ~.,.. )o",o,"'",,~""~J & -.. ......... , ~_~.".:;". """."o~1 ,(rF -"':"1"",*"". ~~'oSI" ___ II<o ...... ",,~ •• n,,,,·~ .......... v· "".T ,~. ~.,...

58

..

Recordable DVD Formats

Write-Once Physical Processes

~;~~;I'!"""'~""""~"""""""I"~~"~ e·~~ ... -.wl"' .. _:,w_w..y!sltl»

Phase.change Recording and Erasing (2)

Incident laser power at reference recordIng speeds: o read .. vet 0.7 mW Q erase level: 5,.:1' rdN o recording: 12 .•. 1.tmW

_~"""'~*"",.~~t_~~&... ... ~ 1f:m"""""'_.""""' __ ot<4"'T.d ... ".",,~~ ... ~,,~

Readout principle: the amO:rph0U6 and tr)I8ta1llM pbno have different refleethle, r.fractrt., and abaorpt~ Indlt::e$ teadlng to amplitude ancllor pha&e modulatlon of me ",fleeted las« bum.

- 33 -

Specific Issues

• Writable and r_rllable materlals are needed, on which data can be enerypted by using II laser beam

• Reliable tracking on the blank media is required to correctly position the laser spot in the radial direction

• Means for precisely positioning the laser spot along the unwritten tracks (i,e., track allocation) are needed

• Logical handling of both written and unwritten areas is necessary during writing

• Preferably, the written discs should have a physical and logical format compatible with already existing read-only discs

Phase.change Recording and Erasing (1)

~";"""(!"';Ii>'~_~~_~~~~1 1loi'~~I .............. \Wt""'<41"_""-$k;r!·~.m.I

Phase-Change Marks

,;... .. t.~N'I>e.~~~.J't,t"""'-#«f'~~*-cl1 ,u~~~_Iw......~~"'T.<, .. """W~1>&(111,'trIK

TEM photograph ot the CD.J{W BtIbWate, H 8Hft ff.om: 1:1\. lnaldt: 01 thedlse.

NOle: The 18Hr spot r.HI the ImpresliMd t.1rUetUre from t:tehlnd the ahown eurface.

TEM - TransMsidon Electron Mlu0900pt'

..

CD.R Layer Structure

_ ......... \I""t'lp;,..".,.~''''1>_ ..... P\)o~1fj!._'''', ,Uk,."..,,·>i>w. ;:~'*......,~ "'~""<~""""'!'~ 11«, ".Ii,"""

OVO+R Layer Structure

Outline

• Recordable and rowritable eve systems

;..ru,0;""'~"t~·,~:4:l'""""-~~~ !(;nSy,.,'tlMtt,a.,li_""',"'_d't~,~q_~

..

- 34-

DVD-R Layer Structure

r:r'~;:,,:'~

~~~: ~\=.,..:::

_~. _~:.t,~_~!a",".,..... .... ~,';"~ __ ... ol!l ItliV "t."", ........ ~~..,:""'" jI"''''''''~~'''l'':'·''''''''J> -lrwt Ht ~

DVD-RAM Layer Structure

The Wobbled Groove

Note: the gl'OCNft II! lOcated neat., to the entrance- ."rtaee qf the taser bQm than the Janet

I'UflctiOIl!l: ;;I Allows trackIng on blal'1k otK. o when modulated k'! frequency Of'

phue, aK0w9 ~~$$Jng of the \U1wriHe" .rea$ along the traek

...,. .. t''''''''i''W~,._...,.j''''...nI~ ... _r __ ~ ... r.c~ ............. ) ,(f("""",~,.; ~_!koj;. .. """d1:""""", ... '1'~""~

..

Wobble-based Tracking (Push-Pull Tracking)

_';~.!I''t,*"""~",,,~.~_,~t!':.lIl!><''-''''i ~:f.,.....",_f_,. .... ~<d1 .. _*" .. ~~~.~

Addressing of Unwritten Areas

Wobble frequency: :J cO·RlR.W: 22.05 kHz ;;, DV't)..RJR.W: 14Q.6kHJ:

.l DVO-RAM: 313.761tHz 0: DVD+RlRW: 817.4 kHz

• CD-RlRW (recordablelrewrilable co systems); Absolute tlme In P"'1ln:>OVe (II TlP)

• DVD-RlRW (recordablelrewritable OW systems); Land pre-pil:$!U'1'1

• OVO+ft!RW (",wrltableIWD systems), Address in prellroove (AOII')

• DVC-RAM (random access memory OVD systems): Complementary allocated pit address (eAI'A)

Addressing in OVD-RfRW Systems

• IIddfH9ing method based on embossed land pre-pits • One pre-pit data sequence, Including sync patterns,

corresponds t01S OW sectors (I ••• , 1 ECC block)

-Q'_~~~J-t~~~~,"<Q Ufl~"""".I"",_."".">G'..tt",,~,_~":tt\1llO!

35 -

Generic Write Channel

~"1I.r~M>o,(\"1.~'iW'miI.~l,tJiJij#"'o~I"""""'" ff.f""'!'''''''~ __ :_''''''W?~_~,,''''H ]i\;.

Addressing in CO-RIRW Systems

'3.0HHz

I I

."""';.$""!f .. ,,,,,~_4.~~~~l :l:;F~!'lmik, ...... I~l.I"'f"'''''<'I!!'·IU1RlI»4

1ATII'bft

Addressing in DVO-RAM Systems

• Addressing method based on embossed headers, called complementary allocated pil addresses (CIII'A)

• Headers of 2,048 channel bits containing sync fields, addresses (Including error correclion), write strategy Inlormatlon, elc.

... -'" .. 1~

.,.

Addressing in OVO+RIRW Systems

• 93 wobbl". correspond with 2 sync frame. of user data • 8 wobble. (1 AD!!' unit) out of 93 are modulated In phase with

ADIP data • 1 ADIP word = 62 ADiP units" 4 physical data seetOI'$

""'""v. ""'~"..~ ~""""'~"""'11\, .,. ........ ,.",.. Jl"""""I<o<.~ .. ~'I) It or .... ""', ... "'" h,.;t""",, u .......... ~,~ ;""." .... ;., .. iii •• '1l.~_

Outline

Physical Dimensions

7\l

1\3

36 -

laser Power Control During Writing

~ is! com!nO"ly used to ~luatetM~ing

perfc.rmonotofor. medfe;

-.{. _(I't>o_~ .. """,~:"' __ r>dlr~ll_"~= IU.~_:_:Io ... _u..""".I""'''''''''_Jt·~>t.1\i(i(

p ~ .il +.{,

Al-A2

..

History ~..:> DHI.ntr:tl4'~·

• Cooperation between Royal Philips IfIectroAi"" and Sony Corp. o ,tartMiln 1991 end I.d Wilhin rwo )'Mrs 10 Ihe digital videQ f~ (O'Vfij o r.-d I",," fi,slllloed to obtain \U! GS per 1.2-cm. sirtgte~r meodium

{phaM<han9B. iartd"9toOYe ... cording) Q blue-viol81 Ntsllr. u"<l in 1m 10 amvl! sl22 Cia

• Pioneer Corp. produced 22.;3B r.ad"",ly media In 1999 and Introduced advanced signal processing techniques to improve the bit detectlan MatsushilJl electric IndUstrial Co., Ud. added In 2001 •• perl' •• 'n the field of wobble signal processing. phase-<:hang. materials, P'Qtection cartridges, media manufacturing

• If_I, LId" Sharp Corp .. Mltsubishl Ele<:trlc Corp .. Samsung Electronics Co" LG Eleelronlcs, Inc., TO!( Corp .. and Thomson Multimedia SA Joined the consortium In 2002

• Dell Corp. and H_.packard Company jOined in 2004 • Blu-my Disc R"',lIabie (BO-REI standard released in June 2002 • Work In progress to reI .... th. BO·ROM and BOoR standards

~~_{fl!>ll;l"i-c~.~_l"'*t/!':~_\ cJ:::t~'!~_<4 .. 'T"'~_~~J,~

Optical Storage with High Density Optical Media

• Crosstalk be_n neighboring tracks dUe to a "",a. lra<:k pIU:h • Intersymbol interterenee ~S!I due 10 closely spaced data pattern. • .... r\lO sensltlvity to disc lilt {radial and langentlaQ • New mastering lechnoleg'''' (eleetron booms. deep ultravioletl • Reduced laser poww margins during recording

• Et<: .

...... w\ • .... ,' .... ''''''~'''_" ...... 's-J,._..,..,~_'P-M;f~~N Jf?'fi.f."""' ....... r~.<I: ......... u,..". .. >.y.>fT .. ,_.*">r<)j,_

Optical Scaling

25-68 Blu.ray Disc Parameters (1)

_'''_;'I~~~._ ..... r...,#"..;r;:;..~ ~:l\~t~_"""""">OIJ"_'lif_1iIq~~

BO·ROM, BD·RE, and BO-R Media

aO.fiOM

lnvertecl Stackl: -hardcoaUng j2jJ.1'n} -(;C>\letHJ'}"Tt11'1!)j.ltn~

-Gleleetric..al'ld ph.atie..;hal'lge l;ayers or dye fUm ttO"sonm ..ach)

- r.fJocUve ~ (70 .. 120 jU1'\ j -Sllbstrare(1.1 mm)

..

- 37 -

Outline

• TIt~ Blu ..... y Disc (BO)

. 2';' < >~},,~·'·n: '. "' c 'ftl+l •• d and writ. charllM't.

""' .. :. _;?N:""_""""_Jg"_~~1l>\~~a.j *:n..,:vp:......,.~-.......U".> ... >~y,Jf>l<'''_,.IIto\''a_

25-6B Blu-ray Disc Parameters (2)

1) ~ tiIlHIHt -,000> bil.ftl tlld:~r;: .. £ti..idGllrm.~4AlMbItrt :IIlo1d~IRPEG"'"'"'''IlI/!fl!l-'lIIb1111

1i<I4-<'$j"'f,..t>-~""~;"'''''''_''<>IIi)<I!'~~1 ~rr~""""!,,",,"">_'~"'J"''''''''':M'H'''-'Y~P.,2l)I.o:

• Tltt' Blu-ray Disc (BO) " • ~') ~; ,,", ' A,:i<:; o st:! &peeiftclltions

-(., '.," .. '. ~.;,,~

..

••

Advanced Signal Processing Ouring Readout

~." ~.'f'a;.'1«ll""';\...:.-.:<l"'~_""~~~"_"''''' ;ffr~H'V_ r_""",;;'.-m>r""i«-'"",· ~~~ ~

Error Correction Code (ECC) Clusters

[~M~~~j

.. HonitBtGf .quoilRUon (limfdng .qumil:er) '" used to booat lhe kMHt MftpffRldft ._!>It u.t.etion tRlmiquM ~,Pl'WLI'" ---. ~!gb ilOtstflttl~ ..........

Nonfin-t e<juclinriotl ~IIM~ttet"t

• alS eo.umns can be retrteved and decoded fastvr than the el'ltlre ECC d\I$W • Robust o~rellon for both random ana burst t:rrors:

o powoerl\l! AS codes fOr LDC lIl'Id SIS. dab Q aJ!LDCbytei in.rowbdw.tf!twt'fi'l"OneC!u.es$bYtft .,.ftaggt<ia.a~

"''''''';'.li'w.>~,._,_,,,,,,,+. ... _,,.,,.,..,.:!!,,,,,,,,~,,,,, .. ''';!\t (r'if. $";·~'''''''''',~; .. ;:h,_1,1",_"""".;t •• "..,.,..vi··".> 'ij. u<;<

Outline

• The Btu-ray Disc (&I)

:;; O.uc: !!itDrlige on Be i~N;;

••

·38 -

Addressing in BD·RE and BO-R Systems (1)

'" M.1o<"_'Wffl~ .. !IG."'; ")"~_""~7t1""", .. Qo_<'~ ""tit:~_ !"",c:-""'!'Of'.....,....~iI>' .. l~ ..... ~~tol.,!'.~$I>i

'0' Monotone ,_ ....

'VAt. SMi*·i!ik.W,!!,. eM .,

"i"F99Mi+W ihi H " eve Error Correction Capacity

• SIS columns: max. 16 bytes can be corrected ~ all bytes in a row ~eetI:

two .rrcneou. BI8 bytp at\CI mark" 8$ .TUUm

• I..OC columns: w ~.\f~d eorreetlon:

m.u.32bytn D .la.\fr~ eomtetlcm

comtMrred w1th InterktaYlng: max.641'>yte$

Practical error correction capacity (264S discs): 11.18 mm otlracl! length

Toward Better Video Quality

fEB BrSe~ .comoctlDll

Miscellaneous System Spec.ifications ~.:> $4.I,/AgDl.9f,"

• Compressed hlgh-deflnltlon (HD) video can be recorded In MPEG·2 lonnat at 20-30 Mbit!$

• Defect management • Powerful copy proteetion scheme for rewrltable as well aa for

read-only media

• Fast random acCOS$ • Optional cartridge

Outline

• ,,, , .\1V Y,'Y.;oo·f:0

• What aooul the fuwr.?

'"

Top 5 Trends

• Reewding apHd rA:e* in OVO sytten'f* UIX~4X~U:~«.Xu.'ICX,.,

.. t.'!Ilnlaturitaflon

...... ,--;."'-..;;., • CoJ>1ft19'ht management

l3 t:Of:IY ptll~!On;.l1 dlmbllUid <Xmtem 111Mi1:..,ntytlW'1d.aJ ;:) WPYP't'll~f\;orfMXJrrfOO/~mat'Ao;

.,. &a~rd.aOd t:rQ~'A'le;e C"~Ubillty ;;s ~.avi)<)e""I)tltr.1~~lkI4~Ofl.or>tpla!f«m

;'ffA~~r~

• New te.atures and functlons ~ ~"'I!.!~~lK1;~¢~h'dll1l:tl"'$

!M~liO-4. k~, WftMi, fnpSPRo, ATIO:AC, ttt.) :.'I vtOIiC~1t\raI.qI~~met .... ~.

YO

- 39-

How Muc.h Data Can We Store on Optical Discs?

Cartrldg. oJ the eIU.qy~K

theOVOaucceaor .

Preliminary Impression

'~""'y"'8<"',~'foIi:p<w..-.-__ ... __ ;<oIli»;t':~""~) ;td·~,f_-..... ... r"_'iI!' .. IoI.;l'",-

Short-Term Prospective View

Emerging high-density optical disc formats; Q ~e eJlt.t)aeltlea: 15 ... 30 GS on rme s!l'<gte-iayer side t:. bluehtl<N«t Laeel'$ (W8Vefength around 405 nm, Q h.igh numbrt§1 apertures {above 0,8) o thin and wry thin substrate, (80 ... 100 nm) D redUQedflylrt;~ht$f50 .. ,500flrttl •• tt:.

."

so

, ..

,oo

Miscellaneous Optical Recording Technologies

• 1~nf$1 ~ready In -tQmme-rdal prototype SYfdems tI MtIlm6yer.~~slWaQt Q Ml#tilM:l~ tlPJtw~~

.. DeWlopments- relaDwty cion to commercial Pfo~ (J ~irnetllil(.oIlM~ltltMtQe

Q A!l"'ano:e<ImIII~~{tI~,PNDO,t:lC.) D HMr~ nI(:,Ording {CIIft!'IdkWI~ "kl:wtI'h metallic probft {$'4Itr .... l!N8l tl t<ologmphiC~

• Academk::llndustTial baste reHaroh I:l C-Ol'tV4lt!tiClnal, drftr~-limI6d opUC4If;W--oe with unr~t lIght Q YeryhIgh-NAOfJtk.f'ItCQ1di~g(opticaISUpert'lKOIiJtioni

1;1 MuttibtoMl'I. I'\'Mt>Ii8ld YC$I!L~ f«'(Ird'".l1 w f~(:'rdomalnopU¢al~ Q 'tw(l-photl)fl<'bsorpiitm

.. Pm:ltooteftilciJ'o!&optiealrettlfding

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Copyright Note

• Tne copyright Of the whote prs$I",t«t:lon belDl"I98 to Ra)'31 Philip. Electron!cs, the NetheriandfiL

.. t<luwer Audem~e Publishers holds the upyrtgnt Of many drawings \l&Otd 1n this pr.~ntatlon C'ihe CO~ROM ~. A aM!' &}'$tlWn De,cl1pUon'",.

.. other arawlngs, the preMntatlon approaC:h .• nd the organIZation of tho pUbliShed material bear tile Copyright Of $orin G. Stan and: will be published 500fI In a monograph about ()pti~'1 $to~.

.. No part of the rnat&rtal pto~ by mls eopyJlght nQtl~ may be reprodUced or utilized In any form or by any mftOS, .lltCtrot"l!e or rnechanlcal, Including plwtoccPY\r19, re-;;¢rdlng tJt by any htformation slorage and retrtaval sYliot.m, without written permlWton from the CQPyrlgh1 owner. .

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- 40-

Outline

.. Round-olT

End

Acknowledgements;

To our colleagues from Philips Optical Storage, Philips Res;;arch, and Philips Semiconductors ~Home Entertainment Solutions) for our fruitful collaboration.

a_"'.~l!~l<I>\.w-", .. ..,.-.: .. ~_~r./!lIIif~·'l u;::r~t-.;,_,~·"f1>t .. T"""""'j(J~,"",,1"~

,ouraltention!

41 -

Laser Beam Recorder Mastering of Optical Disks

Introduction

Mastering is known as the process for making the stamper as used in the replication process of read-only (ROM) and pre-grooved RIRW discs. In brief, a substrate covered with a thin photoresist layer is illuminated with a modulated laser beam, focused into a small optical spot. The modulation of the beam is according to the data pattern to be written. The exposed areas in the photo-sensitive resist layer are dissolved during a development process with an alkaline solution and remain as physical holes in the resist layer. Sputter deposition of a thin Ni layer, which is subsequently galvanically grown, results in a thick metallic substrate with protruding bumps, the bumps representing the inverted pit structure. This nickel substrate with bump structure is referred to as stamper and is used for replication of data in an organic substrate, for instance via injection molding.

Since the invention of the CD the storage capacity on optical disks has increased from 650 Mbyte to 25 Gbyte on a single sided 12 centimeter disk. This has to be realized by shortening the channel bit length and reducing the track pitch. Therefore it was necessary to design new mastering equipment with a smaller spotsize and less track pitch variation. Also the wide variety of existing formats and the need for development of new types made it inevitable to use laser beam recorders with dual beam capability. High-density mastering requires an optical spot as small as possible with which the data pattern is written in the resist layer. Liquid immersion is a way to increase the numerical aperture of the objective lens, thereby reducing the optical spot size. In the last three years this technology was developed at Philips Research and has proven to be a potential technology for mastering of next generation BD-ROM discs. In cooperation with the supplier of the mastering equipment this lead to the currently used liquid immersion mastering equipment.

For the development of the CD format a laser beam recorder was used based on an Argon laser with a wavelength of 458 nm and an objective lens with a numerical aperture of 0.80. The CD-Audio or CD-ROM disk contains a continuous spiral of pits with a trackpitch of 1.6 on, recorded at a constant linear velocity. It could be done on a single beam recorder with only one active optical element: an acousto-optic modulator to create the desired pitlengths. However, to be able to control the intensity in the spot, a second active element was needed: an electro-optical modulator. This modulator has a very high frequency response and filters the intensity noise of the laser. Unfortunately it is rather bulky and requires a lot of power and most important: it has a poor extinction ratio (typical 1 :40). The acousto-optic modulators have a high extinction ratio (> 100), are small and consume less power. That is why they are used to generate the desired format by modulation of the incoming beam.

The CD recordable and rewritable formats consist of a continuous groove that is wobbled to encode the timing information. The wobbling capability requires

(,,\) 010 -42 ~~

the installation of an acousto-optic deflector. Though the frequency of the wobble in CD-R(W) is very low, the bandwidth of this deflector is about 10 MHz. Depending on the rotation frequency of the master, it can also be used to write very wide grooves or in combination with the modulator interrupt the groove and write a pit in between the tracks.

With the rise of the Magneto-Optical (MO) disks, the need for dual beam recorders was created. In general these formats consist of a continuous spiral groove with on the land in between the grooves a number of pits containing the address information. A beam splitter is used to generate two separate and parallel laser beams, both can be modulated and deflected independently. A mirror reflects the second beam back to a combining cube. By tilting this cube it is possible to create a small angle between the two beams, causing a difference in the position of the focused spot on the disc. With this configuration one beam can be modulated to write pits, while the other beam is not modulated to write continuous grooves.

The increased densities needed to raise the storage capacity from 650 Mbyte on a CD to 4.7 Gbyte on a DVD had to be realized with a smaller spot in the laser beam recorder. Since the spotsize is determined by the wavelength of the laser and the numerical aperture of the objective lens (see figure ), both were changed to obtain the largest reduction in spot size.

• •

minimal spotsize - N NA = n sineS)

The desired pitsizes and the reduction of the trackpitch to 0.74 011 in DVD lead to the implementation of a Krypton laser with a wavelength of 413 nm and a numerical aperture of 0.90. Because of the demand for the possibility to write MO formats, and the possibility to write recordable and rewritable formats, a dual beam recorder with a de1'lector in only one beam was built. Because of the smaller trackpitch, the variation of it became more significant with respect to CD. While for CD a trackpitch variation of 30 nm (3IJ) caused no problem, a variation of less than 15 nm was required for DVD. Therefore the mechanical and optical design of the recorder was completely different. It was decided to change to moving optics and two piezo controlled mirrors to stabilize the incoming beam on the moving sledge. To keep the dimensions (and weight) of the sledge minimal, the optical components are placed close together and one deflector is left out. With this configuration it is possible to record all existing CD, DVD and MO-formats. Because the market for MO disks is declining and for the different types of CD and DVD (excluding the DVD-RW and DVD-RAM) there is 110 need for dual beam capability, it is worthwhile considering the change to a single beam configuration.

- 43 -

For Blu ray Disc (BD) the specification for the trackpitch is reduced to 0.32 on and the channel bit length is reduced to 74.5 nm to increase the storage capacity to 25 Gbyte. To reach this, a joint development between Philips and Toolex was started with the goal to design a Deep UV laser beam recorder. The laser that was chosen is a frequency doubled Argon laser with a wavelength of 257 nm. Because of the uncertainty of the final layout of the BD format, it was decided to incorporate dual beam capability in the design. In practice it is not implemented at this time. The mechanical design should enable us to obtain a trackpitch variation smaller than 10 nm (3D). The current BD rewritable format exists of a wobbled groove with a duty cycle of about 50 %, resulting in groove widths of around 160 nm. Initial tests have shown that this recorder can write complete BD rewritable discs within specification. However, for the BD-ROM format the dimension of the smallest pits is close to 120 nm. Although single pits of this size can be written, it appears that when writing a full format with varying pitlengths, the specification for jitter cannot be met with this recorder. For one of the future formats under development, TwoDOS (Two Dimensional Optical Storage), several test are recorded with pitdimensions of 120 nm (FWHM). In this format the pits are arranged in a hexagonal raster, but they are all the same size. The trackpitch used was as low as 214.3 nm. With an extra process step (development before recording) the contrast of the type of resist that was used could be raised. This resulted in very repeatable results for TwoDOS, but it still appeared to be impossible for BD-ROM.

Because reducing the spotsize even further could not be done by lowering the wavelength, a different approach was developed on the Philips Research Labs: Liquid Immersion Mastering. The numerical aperture of a 257 nm DUV recorder is increased by adding an extra lenselement to the objective lens and replacing the air in the gap between the lens and the master by water. The water is injected in the gap through a tiny channel just before the lens and the resulting small trace of water is sucked up again from the master half a revolution later. The obtained numerical aperture is 1 .20. Although the laser beam recorder is still in an experimental phase, some very good BD-ROM disks have been recorded with jitters well below the specification. Densities up to 40 Gbyte have been recorded without using any write strategy.

Future formats will definitely require an increase in storage capacity. However, at this moment it is unlikely that this increase can be achieved by further reduction of the recording wavelength or higher numerical apertures. To make another major step in density, changing from optical recording technology to electron beam recording could be a solution. Furthermore there is still room for improvement in the processing area. Investigations in different resists, developer fluids, reactive ion etching and phase transition mastering are ongoing. In parallel with this it is also of great importance to improve the stamper and disk replication process, because the ever decreasing pitdimensions will make separation much more difficult.

- 44-

- 45 -

Magnetic Random Access Memory: The memory of the future?

L. Lagae, IMEC, Belgium

Our world will become a wireless world ... Handheld computers and phones, digital cameras, music players, intelligent home devices, all these electronic devices need a memory system to store their operating instructions and information. Industry is searching for the 'holy grail' in memory technology to improve the performance of all these wireless devices. The memory of the future should have low cost, low power, low voltage, ease of integration, nonvolatility, infinite rewritability and especially speed compatible with the speed of the device logic. Magnetic Random access Memories (MRAMs) are applying for this position of 'holy grail'. This paper reviews some important technological and physical aspects and challenges that could still obstruct the road to commercialization.

The MagnetiC RAM technology uses the magnetic orientation of tiny magnets to represent the two stable states of the bits and a magnetization orientation dependent 'magneto-resistance' to read the state of the bit. A basic memory cell consists of two layers of ferromagnetic material separated by a metal layer for a spin-valve (SV) or a thin insulating barrier for a magnetic tunnel junction (MT J). One of the ferromagnetic layers is pinned, meaning that its direction is kept fixed by an exchange contact with an anti-ferromagnetic layer. The direction of the free ferromagnetic layer with respect to the pinned ferromagnetic layer represents the binary state of the cell. If the two layers are magnetized in the same direction, their electrical resistance is low; if they are magnetized in opposite ways, the resistance is high. The magneto-resistive signal is about 60 % tunnel magneto-resistance for MTJ's [1] as opposed to 19 % giant magneto-resistance for SV's [2J. The higher magneto-resistance for MT J's and the possibility of higher density due to the current perpendicular to plane-geometry makes the MT J's the preferred choice for memory cells, as explained in Figure 1. Reading the magnetic state of the free layer involves a simple resistance measurement of the stack of materials.

Each cell sits at the intersection of perpendicular wires that run closely above and below the cell as in Figure 2. To write a bit, a current must pass through two intersecting wires. At the crossing point, the currents induce a magnetic field sufficient to alter the magnetic orientation. As can be seen on the graph, a combination of two currents will make writing one cell easier and leaves the other cells unchanged, this is named the coincident current selection scheme as it can be used to select one bit out of a complete array of bits.

The complete MRAM architecture generally adds a selection transistor to every memory cell, to make bit-selective read and write easier as can be seen in Figure 3 [3J.

- 46-

a)

SV MTJ Current in Plane Current Perpendicular to Plane

Figure 1 (a) Magneto-resistance (MR) in spin-valves (SV's) and (b) magnetic tunnel junctions (MTJ's). The parallel or antiparallel alignment of the magnetization of the top free layer with respect to the bottom pinned layer generates a lower (Rp) or higher (RAP) resistance. The physical origin of the giant magneto-resistance (GMR) in SV's is spin-dependent interface scattering and the current typically runs in the plane of the spinvalve. The physical origin of the tunnel magneto-resistance (TMR) in MT J's is spin-dependent tunneling and the current typically runs perpendicular to the plane of the MT J.

a) b)

Word line

Figure 2 (a) The magnetic storage device (mostly an MTJ) lies at the crossing point of two current conductors. Writing a cell involves application of currents (Iwrite) through both the word line and the bit line. (b) The minimal switching field of the magnetic cell's free layer has the shape of an astroid. Only at the crossing point of the selected current lines the total field (Htot)

being the vector sum of the field generated by word (Hwu and bit line (HaL) is large enough to alter the magnetization of the free layer. The magnetization of the other cells is not touched.

- 47 -

a) b) I

Bit line

Word

VII Selection transistor Figure 3: MRAM has a DRAM-like architecture (a) with one selection transistor and one magnetic storing device per memory cell. Read-out of a MRAM cell comes down to 1) opening the selection transistor and 2) reading the resistance of the element. A cross-section of one MRAM cell is presented in (b).

MRAM is claimed to combine many of the advantages of other types of memory and is therefore considered a first candidate unifying memory [4],[5]. First of all, non-volatility and the consequent absence of static power consumption are intrinsic to the use of ferromagnetic materials. As there is no such thing as magnetic wear-out, the non-volatility and rewritability are in principle unlimited, making MRAM competitive with FLASH-memory. The magneto-resistance measurement provides a non-destructive read-out mechanism, giving MRAM an advantage over FRAM. Additionally, MRAM promises a high density comparable to DRAM due to simple cells and simple array architectures and fast read and write access of less than 10 ns comparable to the speed of SRAM.

But there are several key challenges to making MRAM's work!

One is the difficulty of integrating the materials needed for magnetic tunnel junctions into a standard Ie production line due to their poisoning effect on silicon transistors. Putting all the specific MRAM processing in the back end of the device fabrication can solve this problem. But then there is a thermal budget issue, as back end processing requires typically higher temperatures than the magnetic components can bear.

Another challenge is to ensure a large magneto-resistance, as to relax the requirements on the sensitivity of the sense amplifier and to decrease the time it takes to read a cell. Recently developed tunnel junctions show 60 % MR at room temperature [1] and increasing this value with a factor of two would make sense amplifiers an order of magnitude faster. Different groups are trying out all sorts of combinations of materials to further increase the MR.

- 48-

A major issue is the reliability of the magnetic memory cells. This reliability consist of two issues:

Electrical reliability. The very thin insulator in each magnetic tunnel junction must have a very uniform resistance across the wafer. This is quite difficult as the resistance scales exponentially with the thickness of the tunnel barrier. Moreover, the read/write endurance is limited by the tunnel barrier breakdown at defects and is explained in Figure 4. To increase the uniformity and to decrease the amount of defects, extra planarization steps are added in the fabrication to remove all topography before deposition of the tunnel junction.

a)

defects breakdown

oxide! r/' £ i2j single trap· 0

conduction path

b)

" ' ........ , "~'. 10 years - _\\~ -

. "~.

0.5 1.0 1.5 2.0

vMTJ(V) Figure 4 (a) Breakdown analysis of the ultra-thin uniform AI20 3 tunnel barriers in MTJ's (shown in the TEM photograph) stressed under a constant voltage reveal a breakdown mechanism due to single-trap conduction paths created at defects. (b) Extrapolated life times are well above the specifications [6].

Magnetic reliability. The write selectivity relies on the theory of coherent rotation of single domain particles. However, single domain modeling is often not very adequate, micromagnetic effects such as magnetization curling at the device edges and the nucleation and propagation of domains can significantly change the switching fields. Switching mechanisms, involving domain propagating, produce lower but less reliable switching fields. The origin of the dispersion is that domains can nucleate and pin at edge defects, etc. The dispersion of switching field is a source of magnetic noise that will limit the performance of magnetic devices. One way to get beyond this is to suppress domain formation by adjusting the shape of the element to get reproducible switching events and well-defined switching fields. Fabrication methods with very accurate shape definition should be used to obtain this [7, 8]. Another way is to look for a more reliable switching scheme, as will be explained further on in this paper.

- 49-

Reducing the size of MRAM cells favors single domain behavior, but also causes an increase in the magnitude of the switching fields. This is detrimental to low voltage and low power operation. Reducing the write current requires reducing any source of anisotropy that can increase the switching field. However a small element with small anisotropy has very low magnetic energy and is therefore very viable to thermal energy assisted unincidental writes and this will again increase the dispersion of the switching fields. It is this thermal energy, and the effect on the distribution of the switching fields that limits scaling of the MRAM cell size. An example of switching field distribution measurement is shown in Figure 5.

2t4( Rt-

rS6

1 &100 e I'-

1kb array

Mid POint

o~~~~~~~~ l' III III 22 14 26

Sense Current (J.tA)

Figure 5: Statistical distribution of the switching fields. Low dispersion results in reliable switching and two well-defined states.{9]

One of the most important challenges of designing magnetic random access memory (MRAM) from either magnetic tunnel junctions or spin-valves is obtaining reliable low-power high-speed switching of the magnetization of the "free layer" in these devices. At always increasing data rates of up to one Gbit per second nowadays, it is the demand for speed that is pushing memory technologies ahead. We have to compete with the high speed offered by semiconductor memories today (7 ns access time for SRAM). Along with the development of MRAM devices thus comes the need to understand the magnetization dynamics and magnetic reversal processes at time scales relevant for these devices (100 ps to 10 ns). Strangely enough, almost no experimental data on fast magnetic switching in patterned magnetic structures was available at the start of MRAM development about 6 years ago [10]. How fast can we make these magnetic materials switch? How does driving up the speed of MRAM influence the power consumption? And how does scaling influence the switching? The questions have been answered gradually over the past years: the high-speed low-power requirements have resulted in a new device geometry and magnetic reversal mode than was originally anticipated. To understand why, we first have to understand the physical mechanisms governing the ultrafast magnetization switching processes. The famous semi-classical equation of motion, widely known as the LandauLifshitz-Gilbert equation, describes the motion of a magnetic moment M(t) in

- 50-

the presence of a magnetic field H(t). The motion is a combination of a precessional motion (rotation) around the magnetic field and a relaxation of the motion towards the direction of the magnetic field as is shown in Figure 6. The precessional motion typically takes a couple of nanoseconds to be completed.

Figure 6: The motion of the magnetization in an effective magnetic field is a combination of precession around and relaxation in the direction of the field.

The MRAM prototypes in different companies built over the last years all use the coincident current selection scheme where the local write field at each memory cell is created by two crossing conductors. This approach relies on the balance between the fields generated by single and both wires and the switching threshold as is visualized in the static Stoner-Wohlfarth switching diagrams (see Figure 2). One should keep in mind that this Stoner-Wohlfarth reversal scheme is a static scheme: Simultaneous application of a DC current to both wires can switch the cell at the crossing of both wires. If this scheme is maintained for high-speed memory operation, the length of the current pulses should be long enough with respect to the relaxation time of magnetic motion such that the magnetization can come to equilibrium in the applied field. An even larger concern is to control the timing of the coincident currents. Indeed, for long word and bit lines, the synchronization of the pulses is a major problem, and arrival of the pulse in x-direction before the pulse in ydirection can result in an undesirable reversal mode. Even if the timing and length of the pulses is correct, the reversal field leaves the system in a state aligned with the applied field (at 45 0 to the reversed state) and a precessional motion and relaxation towards the reversed state can take another couple of ns.

For shorter pulses, the precessional character of the motion will start to playa role and structures can end op in switched/unswitched states depending on the exact pulse parameters resulting in irreproducible switching events. A simulation that calculates the first quadrant of the dynamic switching schemes for short current pulses (0.25 ns) is shown in Figure 7. It is important to realize that these short-pulse dynamic switching diagrams look completely different from the static Stoner-Wohlfarth diagrams. For ease of comparison,

- 51 -

one quadrant of the static Stoner-Wohlfarth astroid is indicated in the lower left corner with a white dotted line. A dynamic astroid resembling the static astroid can be seen in the lower left corner of the graph. Additional alternating switched/non-switched areas occur outside of the static astroid due to the presence of precessional motions.

Switch

faster 1 14

12

4

:2

No Switch 2 4 6 8 10 12 14 Hx (kAlm)

Figure 7: Dynamic switching diagrams for a 0.25 ns pulse of a 5nm thin magnetic Permalloy element of 1.6 x 0.4 Drrfwith easy axis in the x-direction. Black areas represent non-switched states. The white line represents one quadrant of the static SW-astroid. (Idea taken from M. Bauer [11]).

Obviously, in such a dynamical switching diagram it is difficult to find the right pulse parameters for a coincident current selection scheme where one pulse should not switch the (memory-) cell and two combined orthogonal pulses do switch the cell (but none of its neighbors) in a memory cell matrix. In Figure 8, the lower left corner of the static (in Figure 8(a)) and dynamic (Figure 8(b-c)) switching schemes are reproduced and the application of the coincident current bit selection scheme is indicated. From Figure 8(a) en (b), it is immediately clear that the field along the y-axis should be reduced in comparison with the y-axis field in the static scheme to prevent unintentional writes of the cells that are lying close to the bit line by the y-axis field alone. Even if a suitable set of pulse amplitudes is found, there is a major issue of sensitivity to pulse synchronization, pulse width and to cell-to-cell parameter fluctuations (e.g. due to fabrication artifacts).

a)

"It b) c)

Figure 8: Bit selection scheme for the static astroid (a), successful bit selection for the dynamic astroid of Fig 6 with reduced field along the y-axis(b), successful and more robust bit selection for the dynamic astroid if the element is turned over an angle of 45° (c).

- 52 -

From the analysis of such dynamic switching diagrams, we also find a large light-colored region that is quite stable close to the y-axis. A good approach is to tllrn the magnetic element at an angle of 45 ° with respect to the current lines. Robust bit selection is then achieved as demonstrated in Figure 8(c). Exploiting the precessing nature of the magnetization vector, we have thus achieved a 'precessional' switch by applying a short pulse orthogonal to the initial magnetization along the original y-axis. The existence of this precessional switching mode was checked on an element of dimensions much larger than typically used for MRAM with an in-house developed ultrafast measurement technique called scanning time-resolved magnetooptical Kerr effect. The results confirm the simulation. Depending on the applied pulse parameters the magnetization will rotate into a reversed or a non-reversed state as shown in Figure 9. The optimal point in the switching diagram is called a 'ballistic switch' (See also Figure 7) resulting in a very efficient and fast reversal making the magnetization rotate exactly 180°, with almost no ringing effects using ultra-short pulse lengths of exactly half a precession period. A measurement of a close-to-ballistic switching trace is shown in Figure 9(a). Ballistic switching could be the approach for ultra-fast low power switching. Elements can be switched with switching fields of the order of 0.5 times the anisotropy field with pulse lengths corresponding to two times the resonance frequency ("" 400 ps). If the critical field is generated by a word line of the same width as the element w =1 om and for a switching field HK = 4 kAlm and for typical precession frequencies of - 2 GHz, the energy needed per bit write is on the order of 1 pJ.

. , .~.:-~~:;/I

+04' " .• ~,

b ., ""'~"":1~ 1

Figure 9: Measured 3D trajectory and projections of the magnetisation vector in a (20 x 8 Orrf) for (a) half-precession quasi-ballistic reversal and (b) full-precession non-reversal. The solid line is the vector tip trajectory and dotted lines are its projection onto the planes.

Apart from possibly being very fast, the main advantage of using this switching scheme is that only one pulse polarity is needed to toggle the state of the magnetic device. This is explained once more in Figure 10. Motorola, one of the major industrial players in MRAM, claims that a switching scheme similar to this one has helped them to overcome many of the issues related to fast and reliable writing of MRAM.

- 53 -

Figure 10: The toggle scheme makes MRAM faster and more reliable (From Motorola)

For future memory technology, we can propose MRAM as a valid candidate, combining many advantages of the other memories on the market and superior to its direct competitors-emerging memory technologies (FeRAM and phase change memories) concerning speed. Power efficient-writing could be achieved with precessional switching schemes. Downscaling of the element

(with width wand length I) will scale the switching field HK - 1 .!... The w

width of the word lines can be scaled equally, such that the power consumption will only increase a little while scaling. However the high current densities are very likely to cause other problems, such as electromigration. Moreover, in these small magnetic elements, switching becomes highly unstable due to thermal fluctuations. From the non-magnetic side, the challenge remains to design write and read-out electronics. More specifically, a current sense amplifier needs to be designed that can read the small MR signals that represent the bit state at high speeds and with low voltage supplies, and different approaches can be found in literature with predicted access times below 5 ns for low voltage (- 2 V) operation [12]. Further optimization of tunnel barrier resistance and magnetoresistance is still possible relaxing the design criteria on the sense amplifier. However there is still one main challenge that remains, before MRAM devices can come to the market: yield! Figure 11 summarizes the state of development by the major players on the MRAM market. The future will point out whether MRAM can indeed fill in the expectations of being a first candidate all-purpose memory promising FLASH non-volatility with DRAM densities at SRAM speed.

54

Motorola 4MBit MRAM

IBM/lnfineon 128 Kbit array

Sam sung 16 Kbit array

Figure 11: Some of the main industrial players and their demonstrators. [13·15]

130ns IOns

[1] M. Tsunoda, K. Nishikawa, S. Ogata, and M. Takahashi, "60% magnetoresistance at room temperature in Co-Fe/AI-O/Co-Fe tunnel junctions oxidized with Kr-O/sub 21 plasma," Appl. Phys. Lett., vol. 80, pp. 3135-3137, 2002. [2] W. F. Egelhoff, Jr., P. J. Chen, C. J. Powell, M. D. Stiles, R. D. McMichael, J. H. Judy, K. Takano, and A. E. Berkowitz, "Oxygen as a surfactant in the growth of giant magnetoresistance spin valves,· Journ. Appl. Phys., vol. 82, pp. 6142-6151, 1997. [3] H. Boeve, J. Das, C. Bruynseraede, J. De Boeck, and G. Borghs, "Bit-selective read and write with coincident current scheme in spinvalve/diode MRAM cells," Electronics Letters, vol. 34, pp. 1754-1755, 1998. [4] Z. G. Wang, D. J. Mapps, L. N. He, W. W. Clegg, D. T. Wilton, P. Robinson, and Y. Nakamura, "Feasibility of ultra-dense spin-tunneling random access memory," IEEE Transactions on Magnetics, vol. 33, pp. 4498-4512,1997. [5] K M. H. Lenssen, D. J. Adelerhof, H. J. Gassen, A. E. T. Kuiper, G. H. J. Somers, and J. B. A. D. van Zon, "Robust giant magnetoresistance sensors," Sensors and Actuators A (Physical), vol. A85, pp. 1-8, 2000. [6] J. Das, "MagnetiC random access memories: technology assessment & tunnel barrier reliability study," in IMEG: IMEC, KU. Leuven, 2003. [7] J. Gadbois and J.-G. Zhu, "The effect of end and edge shape on the performance of pseudo-spin valve memories," IEEE Trans. on Magn., vol. 34, 1998. [8] J.-G. Zhu and Y. Zheng, 'The Micromagnetics of Magnetoresistive Random Access Memory," in Spin dynamics in confined magnetic structures I, B. Hillebrands and K. Ounadjela, Eds. Berlin: Springer-Verlag, 2002, pp. 289-324. [9] P. J. N. Mark Durlam, Asim Omair, Mark DeHerrera, John Calder, Jon M. Slaughter, Brad N. Engel" G. G. Nicholas D. Rizzo, Brian Butcher, Clarence Tracy, Ken Smith, Kelly W. Kyler, J. Jack Ren" and W. A. F. Jaynal A. Molla, Rick G. Williams, and Saied Tehrani, "A 1-Mbit MRAM Based on 1T1 MT J Bit Cell Integrated With Copper Interconnects," , vol. 38, pp. 769,2003. [10] L. Lagae, "Ultrafast tiny magnets for magneto-electronic applications," in IMEG: Imec, KULeuven, 2003. [11] M. Bauer, J. Fassbender, B. Hillebrands, and R. L. Stamps, "Switching behavior of a Stoner particle beyond the relaxation time limit," Phys. Rev. B, vol. 61, pp. 3410-3416, 2000. [12] Edward K S. Au, Wing-Hung Ki, W. H. Mow, S. T. Hung, and C. Y. Wong, "A Novel Current-Mode Sensing Scheme for Magnetic Tunnel Junction MRAM," IEEE Trans. on Magn., vol. 40, pp. 483, 2004.

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[13] J. Gitae, C. Wooyoung, S. Ahn, J. Hongsik, K. Gwanhyeob, H. Youngnam, and K. Kim, "A 0.24- mu m 2.0-V 1T1 MTJ 1S-kb nonvolatile magnetoresistance RAM with selfreference sensing scheme," IEEE Journal of Solid-State Circuits, vol. 38, pp. 1905-1910, 2003. [14] A. Bette, J. DeBrosse, D. Gogl, H. Hoenigschmid, R. Robertazzi, C. Arndt, D. Braun, D. Casarotto, R. Havreluk, S. Lammers, W. Obermaier, W. Reohr, H. Viehmann, W. J. Gallagher, and G. Muller, "A high-speed 128 Kbit MRAM core for future universal memory applications," 2003 Symposium on VLSI Circuits. Digest of Technical Papers (IEEE Cat. No.03CH3740B), pp. 217-220, 2003. [15] M. Durlam, D. Addie, J. Akerman, B. Butcher, P. Brown, J. Chan, M. DeHerrera, B. N. Engel, B. Feil, G. Grynkewich, J. Janesky, M. Johnson, K. Kyler, J. Molla, J. Martin, K. Nagel, J. Ren, N. D. Rizzo, T. Rodriguez, L. Savtchenko, J. Salter, J. M. Slaughter, K. Smith, J. J. Sun, M. Lien, K. Papworth, P. Shah, W. Qin, R. Williams, L. Wise, and S. Tehrani, "A 0.18 mu m 4Mb toggling MRAM," IEEE International Electron Devices Meeting 2003, pp. 34.S.1-34.S.3, 2003.

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·57·

Signal Processing and Coding for TwoDOS

AH,J. lmmillk", W.MJ. Coclle*. A.M. van def Lee". C. Busch*, A.P. Hekstra*, J.W.M. Bergmans"", J. Riani*"', S.J.L. v. Beneden""', T. Conway"~"

*Philips Research Labor;ltories. Prof. HolstIaan 4. 5656 AA. Eindhoven, The Netherlands **TechniC'al University Eindhoven, Den Dolech 2. 5600 MB. Eindhoven. The Netherlands

***University of Limerick. Dept. of Electronic and Computer Engineering, Limerick. Ireland

AbrJr«l-Tb., paper iutrodu~ tilt roucept of T\V.,~ Oimm'"ional Optfc-.d St(l)' fTwflOOS). In (hi, nltta'\pt. bits an;- ",nUt'fi in a roll.'dsthlg of a luunbf.r of bft~ J'I:m'jI !ltat'k~d -.tller m a ll('X~ooal paekm~ Bits with a \'aml:.' • t! at'!;' re-~too pbyskaUy ~ circular pit.,.,.,. eu t11f. di$e. \l'imt biU vitb a \Ure '0' are cbaraderi~d Iw tm. ahseuce of sum a pi(~hl)/I:, .4. s~r (/iffradioo IfItIdI1f i'l It'St'4 to ('8)miate the apal Je,,\>ls for \'8.1'h)ul dianl!l't~n of UK! pits. A stnpl"-w. Vitt-m dcleder is proposNI to pl"rlorm lD bit-dmdimt with ;l limit ..... stm contp/l:xit)' of d:ie trellis. Sirmabl$oo remits are t)hown for vanoos diamt'le~ of tbe pits. A 2D nHduIatioo cod, Ii appUoo ttl .nimill* patmrm that yield ~ lt~ pntbability of erron,,'olll 4f:tedha.

j. J N'TRODUCnON'

A 1\Vo.-Dimensional Optical Storage Con<.'ept (I'WoDOS} is developed. III wilkh the information 00 tbe

fUnldanwnlmly II twG-dimensiooal characwr I The to mlli~ an increase over the 3f4 gi:'n2l1ltion of

(BIn-ray Di$(.\ BD, with a w<tVi.'length .\- 405 nm a NUl'n::'neal Aperl.llre NA "'" O.8t> ill! with a t'actQf of

'2 in and a factor of iO in data rate tbe same ~t1?f$ of tbe optical read-out system). \\Ie pr~ to lh.\:> bilS in a slJ.Ca1I€d broad spiral. Such a spual cOllsists of a number of bit.fOWS stacked upon ~ach otlwr with a rtxed relation. A 2D clo$,('d-~d beugooal omeclrlg of is ch~n because it bas 11 lti% higher ~OOi' fraCtiOn tban w )<itlY~ as proposed in

nunWiP:r of b$:'t.~'s in ooe spirnl is ~hOien to be spim~ a.¥2 ~d by a guard band

bit ~' (Fig. 1). 1he gm band di",~ontinllilv m tOO pha..~ reiatiml. bat\b'et:!.11 two

to all(!\\' a eonstant arealdansil)' aer(lSS

A6i:JUlOllSiUV. it can seNe a~ a sWUng point for 2D ttit··del~iOlt 1\voOOS is, baSt'd on inoo",mve 2D dlaamel and signal prooo$~ ThtH'~fOfl!, it

c\lmp1ementary to the evoh.ttiooai)', pbysital path of scaling ,\ and NA hence it can Offill' U &{u.&l relative advantage

futllfe Near F~id (NFl and Ultra Viokn (UV)

ll. nmomCALOIANNEL

A mUlti-spot light-pmh for parallel l'e:.M.1i:mt is. realil..m1. where cd has SD th~'1e1isti(;S, in ca;;e we ~sum?

the optical chart~l has thi! Wt'H. .. Koov,·n tOOt. ~ hMd 'Cut.off at 111", _ *~A ,"]'"00 nMllalil.eG.

""'-""""'''A Transfer Ftm~tron (MTF) derived in Braat .. Hopkms formalism [4] call be written as:

-{! 11" is the s.pa{ial !l'equen..jI of the inf~tlon 011

and (} is the al.1muth in the lD circ.ularty syn~mc functioo is

Th('Iin2M appH~d 10 tD Ilonnally means Ihat loses

a quite pld approximation wben because me spot diani!e~r is

width Qf a piton the disc. This s..cans a pit the reftec:wd 14lht beam

,un'r",~"'n" me {,NHral ~Jt!Jr'" (CA)

- 58 - •

of the len&. e'IIS in r:M ~ of pit..bits tl'mt.-e w~re the coefIcim'd:$ ~ fer rht. Unea' lAter-symbol iJti.'erft!r-wriMa <tSOl1e el.on8~ted nwt. in dimctioo of me tnlCk ence (ISh fer UIi\I non-li~ar IS) ate given In the 1D-cass ooYo-ever. tlitt at wU: we'sipal folding' ntlt}' m~. due ro OC~ at lil:Je oontip(llJ$ piC areas, OOiWstin~ of a nnmber of l!el~ng bits" whi"h am an of the pit-type. m that CB t~ is no ~iffm.djoo at all and both a .~ pit IlWiI J. non-pit (<rr mnt!') ~ will act as a ~ mirror and show identical ~t iliMls: (_ rht right pan of As a result the clwmd he~ ~y oon..tmear. For e.:m each pit-bit is reoordmf ti til pit...ttole with a size _aller tUn bl.t.ren. Thi~ 1s ~~~11y i~ in me )eft part ~. In thb way. brae oontiguoo~ areas of ptt-mmb are _aided j() that the twu""lif:aemty of the dtJ.Me1 is ~ To estil1We tbe _.rung ltOO-unMrities md to m.r the ~s'$ a

mOOeI is ~Ioped based on th«lry.

il. SCDiar D~_ Model

In optical moording tWftg CA"tL>.dion. the form is " ~e d me l~d illteng,ty in tbe

of the ~ !ens wilen the laser is T6t'!11III1>a

pt}sirimt R,. H tM diK The q-ruatl tnreuity is the ~w~re" modulus of me e{l~.vJ1l~ w,a\'e€ront It dle pupil plaM ~~ by :>. So the .~ sipal t$ equal to

HF(Rp) =<"i~ > wa the InM:{' pt:OOUd is defined as

<: ~Ir >= leA ~·(v);ptl,,)dfl. :> euI. be ~.odJ decomposed b1to a cotlttibllticn from '~I..tImd· ~ and i sum of oomributloos from aU pit..bit!

dult are the area of die ~ ~

:> - <. ~'ftl~ft » >.

With tbl, die sipal _ts fw a.11 ~ ... ttuag<ltW dU5leB are caleu~ A ~f()md clusts ron.sim ct a central bit m the (wce rent~, and <n m ~m Il~ bits ~ die leipurl. oek kau~ me (oomlMl) spot is. clrculariy $)~mc it ~ ttl identify the oelltral bit and the llIimbl;!r of ~(} bits ~ the ~ neighbour bits effeccs), This: re5.t.I!ts in n (<<at of .14 _15. \\'l1ere ead\ of tM .$~l le\'els is with :: (!) tlml » tM number of ~est-neJgbboor An enmple \\'ith tl twx .. 1 lattice ~r 4Jll :. mu a pk~ di~r b = 120 um is sOOwn ill 4. ~ le\'d$ are ~limd to me ~

Si~ "is !« ~., .~~ ~ tAH .. tfiS tm, ~t

II' ~ pi(lt. 1evd-identi~n is on die six nearest ~~ ~ ¢!Ills (tht !iru The scalar diffmaion lllOdel. ~'t!iV«. ti~ the oth« .shells into /iK'lCount. SignS4e\~l vari~tian due to thie m.ftoo~ of the~ wlls is fllot sbown. lnstnd 10 iMti. t~ taken :tCR'.!G aU po~!t!:lle bit.panetm in these sbitUt. nis f.xplal.ns me faa Ibttt tblt sip level of the all land d~r is oot equal to 1 :In we would from <1 nornlai~ ~l furtberntor.e. one (:U

>= {4J omn<e fcrvmyiut>,: si:1~s of tl'tt' mastert<i ptt~bole$. Mid for a pblae,.. of tbe pits. '" =:; 18012'. tflt be-st 'mU.-llff' 11'1 ~ at 1t) .and tblt nm.imum • .al roodubdoo. ·seem til) be 01.-._ with -I ptt.hcle th<:tt ~ aoout twf too

(5~ I.lM <n rht hexlt!on. The optimum p!~le dta __ n"r,,?!; equals:

The ftt € {O,l}. are tlUpri'SSed in the subst'rn.tL>. with lJ.

pR\deined depth m mduce I ~ ;!lffe:rence if> het\W;en light re6e~d from il\ til\ru$ area m:Iid Ught ~6ected from a pit ~ Usit\S (4) in Mid rewo~ lNds to:

HF(Rp) :::: 1 - L (',bt + L d{.j~i~j i ''''j

- 59-

~ =V~ afl

dial •• welte ~Jl:.\d aM fint read~ w ... ua~ exoellent !'li~,me:nt I:II!{ween tile scalar

m. DENSiTY CAU::Ul.ATlONS

A US« bil til dlt :25 (m Bo..foonat has 11 size equal to:

w~ A is the tmck pitd!. l is [be (;~l bit Km8lh and R is the rate d tbe npp (d::t) ~ (we omit an ~dltlooat for tM U\~ad 'Of f'JIiOf ¢01TecOOtl ()Odi1lJ be~u~ u'e anmne it to be ~ in tile ID ad :m et.$~

To ¢!ll~ the density for tbe; 1WoOOS concept u'e imfo~ WaJ Ute ~n of redproc. Uttthces. To do this we _edt., Ute lattil:e by two ~

[. ]vi]. ~nd ~,::

Whh ~ VcOO(ors a ~Mnmn$' manu h a.etioo(\ [5):

L:: [t'?1;r £:b]:. 2. [v!l '1'8] Ul} e." e:i~ 2 I -1 .

TIle i~ cm\ be with a matrix that is the t_ tmEpOsed of L:

This nelnS thm the reciproai m:tioe is also ~ rei.~!JtOIl1IJ lattice 'Nith reciproeai ltmi<::e ~ (lit ;:::::; Stunmem. ~ 1lf)W ~ that I in tile

can be mtrie!.\'ed from tt$ ~d ~'ersioQ if the Fourier TrailUfi()mI is ~wned witbin 11 nmlmnemit do.main of me teC~ ~ [51. H~ a ruooa~31 domain (20 Nyquist celt or Bnll00i11 zone) is m'1I area (hat tw the pro~ that fundmlentru do not Q\'Cctap m that the ooni'$~lQI:I of fu~!ltal domains of all Ute Imiot poilD must tin me 2D sp.aoe F~. 5).

TIle for 1WoOOS is _.d by tbe; ase where the d tile 20 MTP forms e1.~ M i~

fUDtWI~tI1 d'omaift ia 2D fYequetlC)' ~ ~ndi~ ~a~olW ta~ ~ter

1 ( A) 1"" . (J.ll ::= 'ji ZNA :::: '''.i:J nm.

Tbe ~rr~pondift8 am of d~ ~ bit-d mti.l of tile 20 m~ioo

vf .. l(A\~ :: ~H:=!tV! 2,V.4) .

C{lmparlt't~ (9) and ({4) aM for me fKtOr It b to the bud re,,~~s thai. ~ ~able «n$lt)t for 1"woOOS is ill ~"OOt 1 bfpc thm'1I thal of en, Be~ tbe< eut.mt of Ute MTF f()Jfl1U an imcrtberd cirde

tM cU~l will 1IDt:a1l spe.:;t.rnt com-ponents. For this reason !litOOtIlitiofl witt ·be ili"Pli6d IH ~iscussed in .cWu VU

•

• ~ j. .~0I1:Ii1 ~ aM ~ f~ ~ b _4 d tb; llffil" It aM It aJe b _ ft\!lt«'J u.e. ~ipr«a1 ~

tV. SIGNAL Paocm;:sma

A single semi..e~cr laser \lith t is used w obW.fl t t s:pots (0 re~ out tbe ~im m one revolution <1 the disc. 1be SJ»U omit be epII.~ with a minimum ;l~ to avoid _rf~ betweenl:be cdlemnt U$ht fA adj~ Because this 1$ larger thD tbe row-to.ro.w the ~i are ommmi uder a. smaU a. wull respect to the lallptill ~ dim.etion. in the .sigoal ~iIlg lwdware the resWting _lay to this spot-<tmmt'meot must be C().~ W the ~ em be ,.,d into tlte lD ~er (SftI "8- 6).

~. 6. ~ IllIxk ~db:ID

V. 2D Blr D£rocTtON

It is ~. dear from F'tg. 4 that ~ in tile oofl~·S$ ease. thm.shdd <t«cioo u·ith a !Uitmfe~n slicer ievel is IIDt l»s,i'tbie with08t a OO~tt aOUltt (If det~ errors. Almady at this _~t1_ denmy them is m <Werllip £ n the lC\'e 15 wim 11\ otDmlti ·O'..bit and ~s with " «lntr~1 <1'bit. teo t~ eye pattern i~ '~. TM .m.Imber of ~ng ciWlt«S ~s lar9.« at bl~r ~n~s. Therefore. \\'e need t~ ~m is! &lrin! tt. bit~t1n. One ~biHty i:s to ~ :a ~or. Unfom.matleiy, fUll· fledged det~or across tbe c(lm~ width of tbe ~ spiml ·seenu im~ical because Q{ die t'llOfJl»l1S. mte..eomplexifY of tbe a:~ ~Uis. Instead, t.be two-<.limeftiiiOlW is con· sldere<l as a cdl«:tkm of ktlle tugoemill NCb. with a llntited oomber of rows _~ I:f k. ~ ea oM <_ Pig. A ~ble ~ is sh6\vn in the top-left: ~ of this Ip~, The ~h ~i4} for thiS Itmlsilioo. can be as:

If

f5; LIHF1- REF1,cll~. (I 5) ... 1

·60-

where HF, is the bigb frequenq· read-oot s.ignal ad REFl,ili is the CllJSWf.oope~ reiereace 5~gnlll ($0 l is based 00 tlte bits of tbe fint shen ooly~

•• I!} ...

.. ~ ...•.. --.. ~.-.. -... -...• -.--.. -~.-. ft~ 7, ~ of 'JtTi.f'oMI'-' V'itMlt ~ wttll $ '-riIW 1II'iQ -lc» <J.I'l*'-riIW~~, ~~~l.1iM~with·t,

PiX tbe dletmni.tW.ion of refeMtlCe leveB for the top aM batt1)m blt..ro""s d a Wipa Wt reed bitJ tlmt are 110(' ~ fJf the state~ fomins tlte lmUls fJf the cummt stripe, Tbe.rdfJfe" ttw dett,cted output of OU Viterbi..b100k. Vt'I (with fi dfll)' ~ to the b3ck-tmcking depth) i~ partly used fot r«eronoe levd oomputmon in tlte next Viterbi-btook. Vo+1 wlUcll is shifted down by OM bit row. This oo~pt t~ oo~d until tbe oomp1tte stripe is ~ecred, Le. tbe number of V'''tt«b!-bh,cks is: ~ to tbennmbec of blt·rov.'$. in one N<>H spiml. InItial}' we asSlUl1e~. ladin~ to a ~ bit~moo pe~. Therdore. the desaibed procedure is repeated 1t few times {}\'er tlte complete width fJf tbe ~d spiral ro !mpr{}\'e the &election. Slmnlaoon results are shcn&'n in F18. 8. As input sample v.'avdurl;ru for the mno~iou the output of the scabr diffraction mOOeI v.'u used for denSides of t.4x tmd 2x tMt af UD r~~lJ. 10 asre.~s too influenee of non-Uuarity due to ~ f.olding on !:be perfo~ fJf the bit~ct1)r ~al values of pit~er ,",'ere uj;fld in the sLmuumon. No equali¥Jef or etectrornc non-UMadty c~mpellUtlon is apptie\i at this stage. 'file si.gMI-to.M~ kl.vel (S"'lR} is defiood with respect to balf the pea!t-mnpUWde d the sigMt Additive White Gaus.siu N~ (AWGN) l~ assumed for simplicity. It is clear t1w the best \'aiue is docge to lt$Oil; as ,,"'as givtn in ($). N~ dmt in a liM} system a lD~lfzer must be incorpomted to equalize to a c~m~ wge:t re~ which is ~J! t.o achie\'t a limited sure complcit)' m tM Viterbi &etector.

VI. WORST..cASE PATTERNS

BeQUstI v.-e use ta W-PRML bit ~ and ~ (ItlI (be 1iIM being) AWCN, it is ~prUn'e w selrch tor 2D ~ patterns ctw ha\~ JI. minimum Euciidiu di~ve. FOI a liaear cl1ruuwl it is ~Uy ''aiad to search for error pmems ""1m a minimum EuclidiM weight !tttt tlwtsmhskOO through tbe channel As a; reference the ~d filtefB~ (~WB) (~r a smgle bit~JTQr bused lSi. PatterM 00651$(111£. of more bits nt~' ktad to pM~1 slgoo! ~t\¢Cll2otion at the ~t dt.W to lSI eOO thus ~, a loss with respect r~ tbe MFU, An elHusti'ltl searcl1 is cw-1ied out on an arrq of '7 J'O'It.'S in tbe md~ Ilrection ad "* bits in tltftgontial <lrect.wn on a liMar cbUtlei at a denSity of 2J;; tbat <If 00. It was: frond thm ~rns witb a 'closed ri~' of altemttiug +1 and -1 $j'rnoots as indicated in fi~. 9' have !:be highest W~ with respect u) th~ ~WB. The: worst cue OM is th~ most compact .oM at too

ri.!ht s1de of the ti~ and has a loss of 247 l!B with mspect to too MFB. Throsb with a s~ler loss, rum 'open rioss" of atternarins sym\::oh at the ~I)' may sbmv such & l.oss. . . . . . . . . . .. . .. . .

.. .. . .. • • • • • • •

.. • • • • • • + • ..

• • • • • • • • •

Vt'hen we ~tculate: the Haagonal ~ Transform (HfT)

of the U'OfSt C&le p.::mem as in<Icate\i in Fi,g. Wand compare tbIs with Fi& '2 we ee that most of the spectral cont:ent oftbe ~n is nO{ t~nsmitted I:-y too cMnmt

A relared c1U$ o.f error patterns are tbe (l~I) periodic patterns that ~ their fuW1imentat trequenq- bey<:md tbe crumoo! (;Ui-oft' (tu' within (be beugonat fundamenti4l 00.. ntm.n). This is pas.s-ible beQust tbe chanDal cut..of( forms an inscribed were to thf t'Uooamenw ~m.aiD as ~S«1 ie.

- 61 -

re:ctiott 111 The most prominem ()lW lw mc~ vectors on ~ (fOrM" of tim ~w tm.~ ta2.0 t~ space findicated with ~-sy~ in Pi.& 5). 1"tu! genermng matriI; of tnIs 'super.SUUe1:ure' aM its re~iprocai t»tmterput ~

L'=T ( v; ~] [L -t{ =; [; !1]' vn. 2D MODULATION CODING

in Section V it became dear that _ 10 ti:e iGW'..mu

~~$ti(' of the (;~l (!nile mse of ~ ~'if pattern at ~ ~q~ de~ ~5 no opelll~ At a first r~ it ~ attraecr.·e to a ~ to ~ mis unwatm OO~flce of 1St A 'Wwwpai of the data can be obWned by ~iningtN! mab« of nearest neigbooUB, /("'.1'1' with the ~ polarity as rbt bit loca~d at me ~ral latta ¢ell [7}. This, tooSUliS c.:m be _::tb~ in tems of the bipols c~ bits at the t'I8.mI eel (i=O) Imd tbe m oe.ml!t~ cells (j::I, .... 6):

~

L>~'I S ,,<=1

P« Nn'tl :::: 1 tbe two central ~$ m elmmated at low CO ~te aensioo this ln~ ~ 10 allpnt«nwitb a urule ~ Ho~'ef+ we ~. to ¢~fmlCe f« Ute 1'ItIItkiss (){ such a CI.lde by reducing the ~ p8f'1.'11lt«« Utl, for st'llalS \~$ d 1'1_ tile .se1le~ of the l~ levels is klw Hd ~ ~ I'ItIIt is ttlgIL For 1M,. vtllut$ of JV_ whieh ~ ~l1 at WI' ~t ~ of h thai of SO the 6eaenmq of the levels ~s hi,.. and: tN! l~a pin ~ it1laDer and evm ~-3fi\'e.

A more ~ffecti~ (lOtji1't! scteme seems to be tbe etiminati'l')R of tbe i.ntHied w«a ease plttel'M <_ Section VI). To tM:kJe the problem of ~_ a 20 ~ W¢ co~r Utt bit ~ as a oot1ectioll of itm@' U.ntiaJ oon~appit\~ itrips. The ~ev~s in one.~~. a .mpWitD I N!iP (If h rows. We detme a w~l \\'OfG as I seque~ of M· ary (M ::::. 2~ J Non~Rerum-to..z.ero {NRZ) dmfIMl~·lTtbols mat ioo~ tbe type of transitkln between (be .iuccessive b\.(5 dw ate mally recorded on the medium. we (fO~r Utt practical situation of h=3 f« u'hidl 'b'e c:an detine " mium ru.&. I1t ".17" in OW' SW~ Transition DUi!rmtl (STO):

t'l'1 tT;t tf;t 17" X It I 1 I I I I x ... \ x \ ~

\ '. " X \' ;[

NQtt that polarity is nO( illlpommt ~ Wto m~ke Ilse of l\lF.Z clwt:nef symools.

Pm.iicl.lw patterns can be e:~d b) .tWn.g additio=l .~$ fl-s , The SID is modined in $Ocll a that the enooder ",awn this State as soon as a wast ~ pattern builds up. Too :ldditionai stam is e~ed by tbe fact that it it £lmilitr to one of (be originai ~. but rna k 00

fan-«lt (lrIiU~d witb X in tnetab1e below) for a cbael symbol $ that wHI lead to €I ~ cOIltim:&atloR of tbe wO.n.t

ease pattie'rn. The t(lncw~ STD Q'!m be usOO to elim.inate the as dt~ in (l6):

114 tT" Q/J ~

t'l', tT,

0'1 0'1 (1, t'l'1

tTs tT4 -s tTj

tT,

X

t",

0,

(14

tJ~

tT4

17t

<71&

{!'~ 17" q;l

tT4 q-. <"., tV: 0'.

(1, <1:. 0'-' <1" X

tarpt.i~alue of the ~ctiou ~ resulung from dlis STO 1mticl!leS Ute e~ty ct this oonscmnt

1

Too factor ! is ~ eacll c~ symool COnsist> of J btU. To obmiD. a hi!dl eftk:~ ~ twelri tons code words. As a practical. example we ~:a 152-153 ~ resuttln8 in S 1 NRZl ~£, .of J bits.. The problem of

rode ~s is $OI\'Ed by =wlying enum.era.tive eMtlding is ad.ded €orOC-oontr<:!4 and to Msure that we

~ a be4 initial ~ lO start tale en~rntiVl.l pr~ vm. CONCLUSION'S

A 1"wo-Dimen.sioMil Optical SIO,. OOl'liOOpt i$ being dewtoped in whieh the llilta is u~ en a 20 ~ hitti« with tbe aim to r.ea!ize an tl1Cre.e {l\'ef tbe curratt ED-format with I ~ of 1 in data M41a factor of to m ~tl ~. A _"UI',,,.1'I<.t fe:asible .st'l'iF-wfse Vttublis appliH with a limited S~ complexity, for wbk:h 1M optlmttm pit" dianwter is such that a pit..oolill ~" about half (N! area of the ~al bit· O!lt C4Jdin$ to achieve a tow-pas.s ~e of the ~ d~ oot ~m to be tot bit.~ in oor~ ItWe~ Ii 2D mooUlation pr~ Ulat ~imi~$ putl¢uW \\'Ont case pattem~.

ACKNO'WUDGMBNf

This reiearch is part Ocf a Europlan lST-Proj«t. called "'1\\'OooS" (Projeel Nt m~200l-:U168).

REFBIUU4C.ES

ll} W. C.tl!. ·Tlf,'(t·D~ .. bt p,!bli~ Ilt om ~< B. StK.lil 0.. '[ J;mR. n ~ '~ ... tr~~mr f.IIt. w. (tfi « Celt.

Vol, 44 No. J.

~aDOO 1lUI..t ~Qfdi:~~', KIuIw(A~ ..

~ T;N.. ~~Sou_ • IEEE TYQlI$. JuJ.1'h#IJf'1. V<i.. IT-V;), 1. ~ 13m lu, 19?:s.

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Organisatie

Het symposium "Storage Devices"wordt georganiseerd door de IEEE Student Branch Eindhoven.

De IEEE Student Branch Eindhoven (IEEE SBE) is een onderdeel van de internationale organisatie IEEE, The Institute of Electrical and Electronics Engineers, Inc. IEEE is de grootste (ca. 350.000 leden) internationale organisatie van en v~~r elektrotechnische ingeniel.lrs. IEEE houdt zich voornamelijk bezig met het organiseren van conferenties en het publiceren van vakliteratuur. Om het contact tussen de elektrotechnici en studenten te verbeteren is er een groot aantal Student Branches opgericht, waarvan een in Eindhoven, de IEEE SBE.

IEEE SBE ondersteunt studenten tijdens hun studie en probeert ze wegwijs te maken met de ingenieurs- en bedrijfswereld.

Verder verzorgt IEEE SBE de contacten met IEEE en organiseert activiteiten met als doe I de verschillende facetten van de elektro- en informatietechniek inzichtelijk te maken. V~~r actieve studenten is er tevens de mogelijkheid hun organisatietalenten te profileren.

63 -

Dankwoord

De symposium commissie 2004 wi! graag de volgende personen bedanken voorhuninzet:

J.W.M. Bergmans

J.C. Lodder

W.M.J. Coene

Ronald Vogelzang, Computer Associates B.V.

Leon Abelmann, TU Twente

Andre 1m mink, Philips N.V.

Jan de Ruijter, Philips N.V.

Liesbet Lagae, Imec B.V.

Alexander V. Padiy, Philips N.V.

Sorin G. Stan, Philips N.V.

IEEE SBE te weten :

R.H. Pape

E. Vos

W. Yarde

A.J.A. Bosman

Verder willen we iedereen die op welke wijze dan ook heett bijgedragen aan de organisatie van het symposium van harte bedanken.

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Sponsoren

Dit symposium werd financieel mede mogelijk gemaakt door:

Philips N.V.

Shell Nederland B.V.

Computer Associates

IEEE Benelux section

Faculteit Elektrotechniek, Technische Universiteit Eindhoven

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Symposium Comissie 2004

Symposium Commissie 2004

Het symposium 'Storage Devices' dat u vandaag heeft bezocht werd mede mogelijk gemaakt door 5 mensen van de IEEE Student Branch Eindhoven.

Voorzitter: Joep de Groot Secretaris: Bart Gysen Penningmeester: Thijs Reekers Sprekers-commissaris~ Sander Derkzen PR-commissaris: Maarten Lont

(v.l.n.r. Joep de Groot, Bart Gysen, Thijs Reckers, Sander Derkzen, Maarten Lont)

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Proceedings symposium "Storage Devices", gehouden op de Technische Universiteit Eindhoven, Dinsdag 18 mei 2004

Uitgever:

IEEE Student Branch Eindhoven Technische Universiteit Eindhoven Den Dolech 2 EH 2.35 Postbus 513 5600 MB Eindhoven

Editing / Layout Bart Gysen

Cover Design Maarten Lont

©Copyright 2004 IEEE Student Branch Eindhoven

Niets uit deze uitgave mag worden verveelvoudigd en/of openbaar gemaakt worden door middel van druk, fotokopie, microfilm, geluidsband, elektronisch of op welke andere wijze ook en evenmin in een retrievel system worden opgeslagen zonder voorafgaande schriftelijke toestemming van de uitgever.

Hoewel deze proceedings met zeer veel zorg zijn samengesteld, aanvaarden auteurs noch uitgever enige aansprakelijkheid voor schade ontstaan door eventuele fouten en/of onvolkomenheden in deze uitgave.

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