MITROTITIIflËNAPHT
`
`$cience and
`hchnology
`
`$econd [dition
`
`o um by Trylo. i! Füc¡ gü¡p. LLC
`
`IP Bridge Exhibit 2019
`TSMC v. IP Bridge
`IPR2016-01379
`Page 0001
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`

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`OP'TICA I, SCI t.-]N CE À NI) I]NG I NI.]þ],RI NG
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`trioturdittg lidit¡¡r
`Iìrian.f . Thompson
`IJ tti t'¿ rs i t t' ¡¡l' Ilochc sl c r
`Rt t c I t t s t t' t; N" et v' f? t rk
`
`1. Elecfton and lon Microscopy and Microanalysís: Principles and Applications,
`Lawrence E. Murr
`2. Acousto-Optic Signal Processing: Theory and lnrplementation, edited by
`Norman J. Eerg ancl John N. Lee
`3, Electro-Optic and Acousto-Optic Scanning ancl Deflection, Milton Gottlieb,
`Clive L. M. lreland, and John Martin Ley
`4. Sinç¡le-Mode Fiber Optics: Principles ancl Applications, L¿rc B. Jeunhomme
`5. Pulse Code Formats for Fiber Optical Data Communication: Basic Principles
`and Applications, Davicl J. Marris
`6. Optical Materials: An lnlroduction to Selection and Application,
`Solonton Musikant
`7. lnfrared Methods for Gaseous Measurcments: Theory and Practice, eclited by
`Joda Wormhourlt
`B. Laser Beam Scanning: Opto-Mechanical Devices, Systems, and Data Storage
`Optics, edited by Gerald F. Marshall
`9. Opto-Mechanical Systems Design. Paul R. Yode¡; Jr.
`10. Optical Fiber Splices and Connectors: Thcory ancl Methods, Calvin M. Miller
`ît/l^tçl¿, qn¡!
`I
`lon A
`lÂ/,rita
`'^,;th Q;,"\}..õ,t
`trrttt vLvPttvtt
`v. tf,vat,v.
`11. Laser Spectroscopy and lts Applications, edited by Leon J. Radzienski,
`Richard W, Solarz, and Jeffrey A. Paisner
`12. lnfrared Optoelectronics: Devices and Applications, Williant Nunley
`and J, Scott Bechtel
`13. lntegrated Optical Circuits and Components: Design and Applicatíons,
`edited by Lynn D. Hutchesan
`i4, Handbook of Molecr¡lar Lasers, editeri hY Peter K. Cheo
`'l 5. Hanclbook of Optical Fibcrs anrl Cables, Hir<¡slti Murata
`16. Acousto-Optics, Adrian Korpel
`17. Proceclures in Applied Optics, John Strong
`18. Hanclbook of Solid-State Lasers, edited by Peter K. Chea
`19. Optical Computing: Digital anrl Symbolic, edited by Rayrrtond Arrathoon
`20. Laser Applications in Physical Chcmistry, editetl by D, K, Evans
`21. Laser-lnduced Plasmas and Applications, erlited lty Leon J, Rad¿íer¡tski
`and David A. Cremers
`22" lnfrared Technology Fundamcntals, lrving J. Spiro and Monroe Schlessinger
`23. Single-Mode Fiber Optics: Principles and Applications, Second Edition,
`Revised and Expanded, Luc B. Jeunho¡nme
`24" lmage Analysis Applications, edited by Rangachar Kastttrì
`and Mohan M. Trivedi
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`26. Principles of Optical Circuit Engineering, Mark A. Mentzer
`27" I uns Dusigrt, îviilîoti L¿iki¡¡
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`IPR2016-01379 Page 0002
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`28. Optical Components, Systems, and MeasurementTÞchniques, Raipal S. Sirohi
`and M. P. Kothiyal
`29. Electron and lon Microscopy and Microanalysis: Principles
`and Applicatíons, Second Edition, Revised and Ëxpanded, Lawrence E' Murr
`30. Handbook of lnfrared Optical Materials, edited by Paul Klocek
`31. Optical Scanning, ediled by Gerald F, Marshall
`32. Potymers for Lightwave and lntegrated Optics: Technology and Applications,
`edited by Lawrence A. Harnak
`33. Electro-Optical Displays, edited by Mohammad A' Karim
`34, Mathematical Morphology in lmage Processing, edited by
`Edward R. Dougherty
`35. Opto-Mechanícal Systems Design: Second Edition, Revised and Expanded,
`Paul R. Yoder Jr.
`36. Polarized Light: Fundamentals and Applications, Edward Collett
`37. Rare Earth Doped Fiber Lasers and Amplifiers, edited by MichelJ. F. Digonnet
`38. Speckle Metrolog¡ edited by RaipalS. Sirohi
`39. Organic Photoreceptors for lmaging Systems, Paul M. Borsenberger
`and Ðavid S. Weiss
`40. Photonic Switching and lnterconnects, edíted by Abdellatif Marrakchí
`41. Design and Fabrication of Acousto-Optic Devices, edited by Akis P. Goutzoulis
`and Dennis R. Pape
`42, Digital lmage Processing Methods, edited by Edward R' Ðougherty
`43. Viiual Scieñce and Engineering: Models and Applications, edited by Ð, H. Kelly
`44. Handbook of Lens Design, Daniel Malacara and Zacarias Malacara
`45. Photonic Devices and Systems, edited by Robert G. Hunsberger
`46. lnfrared Technology Fundamentals: Second Edition, Revised and Expanded,
`edited by Monrae Schlessinger
`47, Spatial Light Modulator Technology: Materials, Devices, and Applications,
`edited by Uzí Efron
`48. Lens Design: Second Edition, Revised and Expanded, Milton Laikín
`49. Thin Films for Optical Systems, edíted by Francoise R' FlorY
`50. Tunable Laser Applicat¡ons, edited by F. J' Ðuarte
`5't. Acousto-Optic Signal Processing: Theory and lmplementation, Second Edition,
`edited by Norman J. Berg and John M. Pellegrino
`52. Handbook of Nonlinear Optics, Richard L. Sutherland
`53. Handbook of Optical Fibers and Cablesl Second Edition. Hiroshi Murata
`54. Opticat Storage and Retrievall Memory, Nsural Notworks, and Fractals,
`edited by Francis T. S. Yu and Suganda Jutamulia
`55. Devices for Optoelectronícs, Wallace B. Leigh
`56. Practical Design and Production of Optical Thin Films, Ronald R. Willey
`57. Acousto-Optics: Second Editíon, Adrian Korpel
`58. Diffraction Gratings and Applications, Erwin G. Laewen and Evgeny Popov
`59. Organic Photoreceptors for Xerography, Paul M. Borsenberger
`and David S. Werss
`60. Characterization Techniques and Tabulations for Organic Nonlinear Optical
`Materials, edited by Mark G' Kuzyk and CarlW. Ðirk
`61. tnterferogram Analysis for OpticalTesting, Daniel Malacara, Manuel Servin,
`and Zacarías Malacara
`62. Computational Modeling of Vision: The Role of Combinaïion, William R. Uttal,
`Ram'akrishna Kakarala, Spiram Ðayanand, Thomas Shepherd, Jagadeesh Kalkí,
`Charles F. Lunskis, Jr., and Ning Liu
`63. Mícrooptics Technology: Fabricalion and Applications of Lens Arrays
`and Devices, Nicholas Borrelli
`64. Visual lnformation Representatíon, Communication, and lmage Processing,
`edíted by Chang Wen Chen and Ya-Ain Zhang
`65, Optícal Methods of Measurement, Falpal S. Sirohi and F, S. Chau
`
`, l(xl7 hy Tu¡krr & l:rurcir Cnrup. l.l.(l
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`IPR2016-01379 Page 0003
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`66. lntegratccl Optical CircL¡its and Conrponents: Desil¡n and Applications,
`edited by Edmand J. Murphy
`67. Aciaplive Optics Engineering Handbook, erlited by Robert K. Tysorr
`68. Entropy and lnformation Optics, Francis T. S. Yu
`69" Cornputalional Methods for Elr".ctromagnetic and Optical Systenrs,
`-ioh¡t îvî. iarent and Partha P. Banerjee
`70. l,aser Beam Shaping, Fred M. Dickey and Scott C. Holswade
`7i. Rare-Earth-Doped Fiber Lasers anct Amplifiers: Seconcí EcJition,
`ReviserJ ancl Expanded, edited by Michel J. F. Digannet
`72. Lens Design: Third Eclition, Revised antl Expanded, Mílt<>n L¿tikin
`?3" tlandbook of Optical Fngineering, aditcd hy Danicl Malacara
`and Brian J. Thont¡tson
`74. Handbook of lmaging Materials: Seconcl Edition, Reviserl anti Fxpanrletl,
`edited by Arthur S, Diamonrl and David S, Weiss
`/b. Hâncttlook of image uuaiity: Characterization ancj Prcciiction, Bria¡t vv. Keeian
`76. Fibcr Optic Scnsors, cditcd by Francis I S. Yu artd Shi¿hua Yin
`77. Optical Switchinç¡lNetworking and Comptrting Íor Multimerlia Systems,
`edited by Mohsen Guizani and Abdella Battau
`78. lmagc Recognition and Classificatiorr: Algorithrns, Sy.stcrns, ancl Applications,
`¿:dited tty Bahrant Javirli
`79. Practical Design and Production of Optical îhin Filnrs; Second Edition,
`Revisecl antl Fxpanderl, Ronald R. Willey
`80. Ultrafast Lasers: Technology anrl Applications, editerl l>y Martin E, Fertnann,
`Almantas Galvanauskas, and Gregg Sucha
`81. Light Propagation in Pcriodic Mcdial Diffcrcntial Thcory antl Dcsiç¡n,
`Michel Nevière and Evgenv Po¡tov
`t]2. Handbook of Nonlínear Optics, Second Eclition. Revisecl and Expantled,
`Richard L, St¡therland
`83. Polarized Light: Second Edition. fìevised and Lxparrded, Dennis Gcsldstein
`84. Optical Rcmotc Scnsin.c¡r Scicncc ancl Tcchnology, Waltc'r'Egarr
`85. llandbook of O¡:tical fiesign: Seconrl tlrlition, Daniel Malacara
`and Zacarías Malacara
`RÂ Nlrrnline;rr Orllinc'
`f her'rrr¡ [\lrrrnlrie;rl Mndllinrr
`Partha P, Banerjee
`tjl" Senriconcluctor and Metal Nanocrystals: Synthcsis atrcl Flectronic arld Oplical
`Pro¡;erlies, e ditecl by Vit:tr.tr l. Klíntav
`88. High-Performance Backbone Network Techrrology, e<lited by Naoaki Y¿ttnanaka
`89. Semic<lnrJuctor Laser Fundamentals, Toshiaki Suhara
`90" Hanclbook of Optical and Lascr Scanning, aditcd by Gcrald F. Marshall
`91. Organic Light-Emittirrg Diodes: Princi¡:les, Characte ristics, and Processes,
`,!an Kalinowski
`!12, Micro-Optorrechatronrrìs, Hirt¡sltt Ht¡s¿tk¿t, Yosltitada Katagiri, lerttnac¡ Htrot¿¡,
`and Kiyoshi ltao
`93" Mir:rr¡t¡ptir:s k:chrroloi¡y; Srrr;onrl [:riitior¡, Nict¡r.tl¿ts !t, Btttrt:lli
`94- (.)rgarrrr: Flcctrolurnrlcscorìc(.', r:tl tt<:d lty litkya K¿tfa I t
`95. Lrrgrneerrn<J Ilun i'rinrs alrcl Nanostruclures with ion [Jcanrs, Lrtriic Rtrystaulas
`fl6" lnterfcrrrgr¿ì''n Anirlysis for ()¡rtical I-cstini¡, Sccond Edition. l);¡¡ti¡tl M;tl;tr.'¿¡r;t,
`Manuel Sercin, and Zacarias Malac¿¡ra
`97, Laser Rernote Sensing¡, edítecl by Takashi Fttiii artd Tetsur> Fukttclti
`fl8" P¡ssive Micro-()1ltical Alignnrcrlt f\4cthorls, tttlilL:d lsy Hobart A, Boutlrt:au
`and Sharon M. Eottdreatt
`99. Orç¡;rnir; Phok¡vc¡ltaiosl Mee il¿lnisrn. Maie.ri¿tls, ¿¡r¡ri f)tivit;irs, tttlif t:tl lty
`Sam Shajing Sun anrl Niya;.i Scrdar S¿ttacftci
`' l¿i,^,-;
`1rfn U^^,.t!\,-^L
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`101. GMPTS Teclrnolo-qies; Bro¿¡clband Backbone Networks ancl Systetrts,
`Na¿¡.:rÅ'i Y;tnta¡'¡Ak¿t, Kt';ht:i Shitttt'totrt, ;lttrl f iji Oki
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`IPR2016-01379 Page 0004
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`102. Laser Beam Shaping Applications, edited by Fred M. Dickey, Scatf C. Holswade
`and David L. Shealy
`l03.Electromagnetic Theory and Applications for Photonic Crystals,
`Kiyotashi Yasumoto
`104.Physics of Optoelectronics, Michael A. Parker
`105.Opto-Mechanical Systems Design: Third Edition, Paul R. Yoder, Jr,
`106.Color Desktop Printer Technology, edited by Mitchell Rosen and Noboru Ahta
`107. Laser Safety Managemenl, Ken Barat
`108.Optics in Magnetic Multilayers and Nanostructures, Stefan Viéñctvskt/
`109. Optical lnspection of Microsystems, edited by Wolfgang Asrcn
`1l0.Applied Microphotonics, edited by Wes R. Jamroz, Roman Kruzelecky,
`and Emile l. Haddart
`111.Organic Light-Em¡tting Materials and Devices, edited by Zhigang Li
`and Hang Meng
`l12.Silicon Nanoelectronics, edited by Shunri Oda and David Ferry
`113.lmage Sensors and Signal Processor for Digital Still Cameras,
`Junichi Nakamura
`ll4.Encyclopedic Handbook of lntegrated Circuíts. edited by Kenichi lga
`and Yasuo Kokubun
`115.Ouantum Communications and Cryptography, edited by
`Alexander V. Sergienko
`116. Optical Code Division Multiple Access: Fundamentals and Applications,
`edited by Paul R, Prucnal
`117. Polymer Fiber Optics: Materials, Physics, and Applicalíons, Mark G, Kuzyk
`118.Smart Biosensor Technology, edited by George K. Knopf and Amarieet S. Eassi
`119. Solid-State Lasers and Applications, edife d by Alphan Sennaroglu
`120.Optical Waveguides: From Theory to Applied Têchnologies, edited by
`Maria L. Calva and Vasudevan Lakshimínarayanan
`121.Gas Lasers, edíted by Masamori Endo and Rabert F Walker
`122. Lens Design, Fourth Edition, Milton Laikin
`123. Photonics: Principles and Practices, Abdul Al-Azzawi
`124. Microwave Photonics, edíted bV Chi H, Lee
`125.Physical Properties and Data of Optical Materials, MoriakiWakaki, Keiei Kudo,
`and Takehisa Shibuya
`l26.Microlithography: Science and Technology, Second Edition, edited by
`Kazuaki Suzukí and Bruce W. Smith
`
`' 1fXl7 by Tuykrt & I:rrtei' (ilru¡r. lJ.C
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`IPR2016-01379 Page 0005
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`IPR2016-01379 Page 0006
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`MITROLITIIOIRAPHY
`
`Science and
`Technology
`
`Second [dition
`
`edited by
`
`Kazuaki Suzuki
`Bruce 1{. Smith
`
`CRC Press
`Taylor & Francis Group
`BocrRàton London NewYork
`
`CRC Pre¡s ir an imprint of the
`Taþr & [rancis 6roup, an informa busines¡
`
`, :lx¡7 h! Trykrr & l:rorcir (ìrrup, l.l.('
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`IPR2016-01379 Page 0007
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`CRC Pless
`'I'aylor & lrrancis Group
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`@ 2007 by'I'aylor & Francis Group, LLC
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`Libi'ary of Congress Catâloging-in-Publicâtion Ðatå
`
`Microlithoglapl'ry : science ar-rd tcchnology / editors, I(azuaki Suzttki and llrucc \X/. Srnith. -- 2r-rcl ecl.
`p. crn. .- (O¡;tical sciencc ancl engint:e ring series)
`"A CRC title."
`lncltides bibliographical relerences aucl itrctex.
`i S lli.,l- i 3: 97 8 - A -'8')47 -t)0 24- 0 (aik. papr:r)
`ISBN-I0: 0 -8',)47 -902.11 -:\ (alk. paper)
`1. Microlithography--lndustlial applications. 2. Illtegrated circuits--Masks. lJ. lvletal oxicle
`scmiconclttctors, Cornplcmentaly--Dcsign and construction. 4. Mirnufacturing processcs. l, Suzuki,
`I(azuaki. II. Smith, BrLtce W., 1959-
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`Visit the Taylor & Fratrcis Wcb site ¡rt
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`,r,2(ltl7 by'l'{ylor &- lìrrncis Grou¡r, Ll,(i
`
`7-006031516
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`IPR2016-01379 Page 0008
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`Preføce
`
`Over the last three decades, accomplishments in microlithographic technology have
`resulted in tremendous advances in the development of semiconductor integrated circuits
`(ICs) and microelectromechanical systems (MEMS). As a direct result, devices have become
`both faster and smaller, can handle an ever increasing amount of information, and are used
`in applications from the purely scientific to those of everyday life. With the shrinking of
`device patterns approaching the nanometer scale, the wavelength of the exposing radiation
`has beén reduced from the blue-UV wavelength of the mercury g-line (436 nm) into the
`mercuïy l-line(365 nm), deep UV (DUV), vacuum UV (VUV), and the extreme UV (EUV).
`The krypton fluoride (KrF) excimer laser at248 nm was adopted as an exposure source in
`DUV regions and has been used in volume manufacturing since 1988.
`Since the first edition of this book, advances in 1"93-nm argon flouride (ArF) excimer laser
`tithography have allowed for the pursuit of sub-90-nm device fabrication and, when
`combined with high NA technology, polarized illumination, and immersion imaging,
`maybe capable of imaging for device generations at 45 nm and beyond. The next generation
`of iithographic systems for 32-nm device technology will likely come from candidates
`including F2 excimer laser (L57 nm) lithography, EUV (13.5 nm) lithography, electron pro-
`jection liihography (EPL), nanoimprint lithography (NIL), or maskless lithography (ML2)
`Among thesè cándidates, ML2 such as electron-beam direct-write system has been used for
`small-volume device production with quick turn around time (QTAT) because a mask is not
`necessary. Factors that will determine the ultimate course for a high-volume device pro-
`duction will include cost, throughput, resolution, and extendibility to finer resolution.
`The second edition of this volume is written not only as an introduction to the science
`and technology of microlithography, but also as a reference for those who with more
`experience ro itrut they may obtai., a wider knowledge and a deeper understanding of
`thô field. The purpose of this update remains consistent with the first edition published in
`1998 and editãd 6y Dr. fames R. Sheats and Dr. Bruce W Smith. New advances in litho-
`graphy have required that we update the coverage of microlithography systems and
`ãpproaches, as well as resist materials, Processes, and metrology techniques.
`the contributors were organized and revision work started in 2003. Additional content
`and description have been added regarding immersion lithography, 157-nm lithography
`and EPL in Chapter 1 System Oaeraieru of Opticat Steppers ønd Scønners, Chapter 3 Optics for
`Photolithograph, Chapter 5 Excimer Løser for Aduanced Microlithographyt and Chapter 6
`Electron Beøm Lithogiaptty Systeøs. Because the topics of EUV and imprint lithography
`were not addresseã in the first edition, Chapter B and Chapter t have been added
`to discuss these as well. A detailed explanation of scatterometry has been incorporated
`into Chapter 14 Critical Dimensionøl Metrology. Chapter 15 Electron Beøm Nønolithogrøphy
`has also has been widely revised. In order to maintain the continuity of this textbook, that
`proved so valuable in the first edition, these topics and others that may be less obvious, but
`no less significant, have been tied into the other corresponding chapters as necessary. As a
`result, *ã ur" certain that this second edition of Microlithogrøphy: Science ønd Technology
`will remain a valuable textbook for students, engineers, and researchers and will be a
`useful resource well into the future'
`
`Kazuaki suzuki
`Bruce W. Smith
`
`() 2007 by Taylor & Francis GrouP, LLC
`
`IPR2016-01379 Page 0009
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`IPR2016-01379 Page 0010
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`Editors
`
`Kazuaki Suzuki is a project manager of Next Generation Lithography Tool Development
`at the Nikon Corporation. He has joined several projects of new concept exposure tools
`such as the first generation KrF excimer laser stepper, the first generation KrF excimer
`laser scanner, the electron-beam projection lithography system, and the full field EUV
`scanner. He has authored and coauthored many papers in the field of exposure tools
`and related technologies. He also holds numerous patents in the areas of projection lens
`control systems, dosage control systems, focusing control systems, and evaluation
`methods for image quality. For the last several years, he has been a member of
`program committees such as SPIE Microlithography and other international conferences.
`He is an associate editor of The fournal of Micro/Nanolithography, MEMS, and MOEMS
`0M3). Kazuaki Suzuki received his BS degree in plasma physics (1981), and his MS
`degree in x-ray astronomy (1983) from Tokyo University, Japan. He retired from a docto-
`rate course in x-ray astronomy and joined the Nikon Corporation in 1984.
`
`Bruce W. Smith is a professor of microelectronic engineering and the director of the
`Center for Nanolithography Research at the Rochester Institute of Technology. He is
`involved in research in the fields of DUV and VUV lithography, photoresist materials,
`resolution enhancement technology, aberration theory, optical thin film materials,
`illumination design, immersion lithography, and evanescent wave imaging. He has
`authored numerous scientific publications and holds several patents. Dr, Smith is a
`widely known educator in the field of optical microlithography. He received his MS
`degree and doctorate in imaging science from the Rochester Institute of Technology.
`He is a member of the International Society for Photo-optical Instrumentation Engin-
`eering (SPIE), the Optical Society of America (OSA), and the Institute of Electrical and
`Electronics Engineers (IEEE).
`
`O 2007 by Taylor & Francis Group, LLC
`
`IPR2016-01379 Page 0011
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`Contributors
`
`Mike Adel KLA-Tencor,Israel
`Robert D. Allen IBM Almaden Research Center, San ]ose, California
`
`Zvonimir Z,Bandiê. Hitachi San Jose Research Center, San Jose, California
`
`Palash Das Cymer,Inc., San Diego, California
`
`Elizabeth A. Dobisz Hitachi San fose Research Center, San Jose, California
`Gregg M. Gallatin IBM Thomas J. Watson Research Center, Yorktown Heights,
`New York (Current Affiliation: Applied Math Solutions, LLC, Newton, Connecticut)
`
`Charles Gwyn Intel Corporation (Retired)
`
`Maureen Hanratty Texas Instruments, Dallas, Texas
`
`Michael S. Hibbs IBM Microelectronic Division, Essex Junction, Vermont
`Roderick R. Kunz Massachusetts Institute of Technology, Lexington, Massachusetts
`
`Gian Lorusso IMEC, Leuven, Belgium
`
`Chris A. Mack KLA-Tencor FINLE Divison, Austin, Texas (Retired, Currently
`Gentleman Scientist)
`
`Herschel M. Marchman KLA-Tencor, San Jose, California (Current Affiliation: Howard
`Hughes Medical lnstitute, Ashburn, Virginia)
`
`Martin C. Peckerar University of Maryland, College Park, Maryland
`
`Douglas J. Resnick Motorola, Tempe, Arizona (Current Affiliation: Molecular Imprints,
`Austin, Têxas)
`
`Bruce W. Smith Rochester Institute of Technology, Rochester, New York
`
`Kazuaki Suzuki Nikon Corporation, Saitama, Japan
`
`Takumi Ueno Hitachi Chemical Electronic Materials R&D Center, Ibaraki, |apan
`
`Stefan Wurm International SEMATECH (Qimonda assignee), Austin, Texas
`
`Sanjay Yedur Timbre Technologies Inc., a division of Tokyo Electron Limited, Santa
`Clara, California
`
`O 2007 by Taylor & Francis Group, LLC
`
`IPR2016-01379 Page 0012
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`

`

`Contents
`
`Part I Exposure System
`l. System Overview of Optical Steppers and Scanners
`Michøel S. Hibbs
`2. Optical Lithography Modeling
`Chris A, Møck
`3. Optics for Photolithography
`Bruce W, Smith
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`4
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`Excimer Laser for Advanced Microlithography
`PøIash Døs
`5. Alignment and Overlay
`Gregg M. Gøllatin
`6, Electron Beam Lithography Systems
`Kazuaki Suzuki
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`7
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`X-ray Lithography
`Takumi Ueno
`8. EUV Lithography
`Steføn Wurm and Chørles Gwyn
`9. Imprint Lithography ..............
`Dougløs |, Resnick
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`Part II Resists and Processing
`L0. Chemistry of Photoresist Materials
`Takumi Ueno and Robert D, Allen
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`1.'I... ResistProcessing
`Bruce W. Smith
`'L2, Multilayer Resist Technology .........
`Bruce W. Smith ønd Maureen Hanrøtty
`L3, Dry Etching of Photoresists
`Roderick R. Kunz
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`O 2007 by Taylor & Francis Group, LLC
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`Part III Metrology and Nanolithography
`14. Critical-Dimensional Metrology for Integrated-CircuitTechnology
`Herschel M. Mørchmnn, Ginn Lorusso, Mike Adel, nnd Sønjay Yedur
`L5. Electron Beam Nanolithography
`Ë,lizøbeth A. Dobisz, Zaonimir Z. Bøndió, ønd Msrtin C. Peckersr
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`701.
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`799
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`,¡Ì 2{)l)7 by T¡ylor & Francis (ìroup, LLC
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`IPR2016-01379 Page 0014
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`IT
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`Resist Processirg
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`Bruce W. Smith
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`CONTENTS
`11.1 Introduction
`11.2 Resist Stability, Contamination, anct Filtration .........
`'1I.2.1 DNQ/Novolac Resist Stability and Filtration ....................
`11.2.2 Stability Issues for Chemically Amplified I'I"IOST lìesists
`Resist Adhesion and Substrate Priming ..,.
`11.3
`11.4 Resist Coating,..,.
`Resist Spin-Coating Techniques and Control.......
`IT.4,1
`Solvent Contribution of Film Properties
`11..4.2
`Substrate Contribution to Resist Contamination,
`1I.4.3
`Edge-Bead Removal
`11,.4.4
`11.5 lì.esist Baking-Soft Bake
`11.5.1 Goals of Resist Baking
`11,.5.2 Resist Solvent and 7, Considerations ..
`11.5.3 Soft Bake
`11.5.4 Resist Baking Methods
`11.6 Photoresist Exposure...
`11.6.1 Resist Exposure Requirements .....,.......
`1L.6.2 Resists Exposure and I'rocess Performance ...
`11.6.3 Exposure and Process Optimization ...............
`1L.7 Postexposure Bake
`11.8 Resist Development................
`11.8.1 Dissolution Kinetics of Phenolic Resin Resists
`11.8.2 Development and Dissolution lìate Characterization '......
`11.8,3 Developer Composition......
`11.S.4 DevelopmentMethods
`11,8.5 Development Rate Comparison of i-Line and DUV Resists
`Eç and CD Swing Curve
`Postdevelopment Baking and Resists Treatment
`Photoresist for 1 93-nm Lithography.....................
`Challenges for Current and Future Photoresists
`11..1.2.1 Image Resolution and Resist Blur .........
`11,,1,2,2 Photoresist Outgassing
`11.L2.3 Line-Edge Rougluress..
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`11.9
`11.10
`1i.11
`1L.t2
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`Microlithogr nphy : S cience and Technolo gy
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`11.12,4 llesist Pattern Collapse....
`11.13 Photorcsist Issncs for Immersion Lithography
`Refelence.s
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`630
`632
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`LL.1, Introduction
`For the rnost part, conventional single-layer photoresists have beerr based orr components
`with two primary functions. Whether considering older bis(arylazide)-cis-polyisoprene
`resists, diazonapthoquinone (DNQ)/novolac g/i-line resists, or chemically amplified
`poiyiryciroxysiyrene (FHOST) or poiyrnetiracrylaies, cieep-UV (DUV) resisis, an a¡:¡:roach
`has been utilized wherein a base resin material is modified for sensitivity to exposure by a
`photoactive compound or through phtotoinduced chemical amplification. The resist base
`resin is photopolymeric in nature and is responsible for etch resistance, adhesion, coat-
`ability, and bulk resolution performance. These resins generally do not exhibit
`photosensitivity on the order required for integrated circuit (IC) manufacturing. Single-
`component polymeric resists have been utilized for microlithography, including metha-
`crylates, styrenes, and other polymers or copolymers, but sensitization is generally low
`and limited to exposures at short ultraviolet (UV) wavelengths or with ionizing radiation.
`Inherent problems associatcd with low absorbancc and poor radiation rcsistancc
`(required, for example, during ion implantation or plasma etching steps) generally limit
`the application of these types of resists to low volumes or processes with unique
`requirements.
`Sensitization of photoresist materials has been accomplished by several methods.
`In the case of conventional g/i-line resists, a chemical modification of a base-insoluble
`photoactive compound (PAC), the diazonaphthoquinone, to a base-insoluble photopro-
`duct, indene carboxylic acid (ICA), allows an increase in aqueous base solubility. For
`chemically amplified resists, exposure of a photoacid generator (PAG) leads to the pro-
`duction of an acid, which subsequently allows polymer deprotection (positive
`behavior) or cross-linking (negative behavior). Other similar processes have been
`developed (as discussed in Chapter 10) and may involve additional components or
`rnechanisms.
`For arry resist system, the therrnoclynamic properties of polymeric resins play an
`important role in processability. During the coating, exposure, and development
`processes of a resist, an understanding of the thermodynamic properties is desirable
`bccause the glass transition temperatnrc (Tg) of a polymcr influenccs planarizability,
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`materials with values above 200"C ate not suitable because of poor mechanical per-
`fonnance. After three-dimensior-ral resist features are fonned, however; a thermoset
`material rnay be desired in which the polymer does not flow with ternperature ancl a
`T" essentially does not exist. 'I'his ensures the retention of high-aspect-ratio features
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`eering of back steps during single-layer resist processing, the control of polyrner
`thcrmoplastic and therrnoset properties can be made possible. Fcr negative resists, the
`situation is inherently simplified. Coated negative resists are thermoplastic in nature,
`with a well-defined T, range. Upon exposule and subsequent secondary reacttons,
`cross-linking leads to a networked polyrner that will not flow witl"r tenperarture.
`At the temperature of clecornpositiorr (T.1) the polyrner will break down ancl begin to
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`Resist Processirrg
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`lose significant volume. Imaging steps are therefore responsible for the production
`of thermally stable resist features. Operations are often included in the processing of
`positive resists that can accomplish similar thermal stability enhancements.
`This chapter addresses the critical issues involved in the processing of single-layer
`resists materials. Process steps to be discussed include:
`. Resist stability, contamination, and filtration
`. Substrate priming
`. Resist coast
`. Soft bake
`' Exposure
`. Postexposure brake
`. Development
`. Swing effects
`. Hard bake and postdevelopment treatment
`
`The step-by-step process flow for DNQ/novolac resists has been covered elsewhere,
`and the reader is directed to these references for additional description [1-3]. Specific
`details are given here for positive DNQ/novolac resists and both positive and negative
`DUV chemically amplified resists based.
`
`11.2 Resist Stability, Contamination, and Filtration
`11.2.1 DNQ/Novolac Resist Stability and Filtration
`DNQ/novolac resists have proved to be robust materials with respect to sensitivity to
`thermodynamic and aging effects while stored in uncast form. A resist shelf life of several
`months can be expected with no significant change in lithographic performance. Because
`resists are considered for application in production, the stability of materials at various
`points of the process also needs to be considered.
`For DNQ/novolac resists, aging can lead to an increase in absorption at longer wave-
`lengths, Resists materials are susceptible to several thermal and acid/base (hydrolytic)
`reactions when stored [4]. These include thermal degradation of the DNQ to ICA followed
`by acid-induced azo dye formation and an azo coupling of the DNQ and novolac. A
`characteristic "red darkening" results from this coupling, induced by the presence of
`acids and bases in the resist. Although long-wavelength absorbance is altered by this
`red azo dye, the impact on UV absorbance and process performance is most often negli-
`gible. Degradation mechanisms can also result in cross-linking, leading to an increase in
`high-molecular-weight components. Hydrolysis of DNQ may occur to form more soluble
`pròducts and hydrolysis of solvents is possible, which can lead to the formation of acids
`iS1. fne practical imitation of shelf life for DNQ/novolac resists is generally on the order of
`6 months to 1" year. Once coated, resist film can absorb water and exhibit a decrease in
`sensitivity, which can often be regained through use of a second soft bake step. As will be
`described, pïocess delays for chemically amplified PHS resists are much more critical than
`for DNQ/novolac materials.
`A larger problem encountered when storing DNQ/novolac resists is sensitizer precipi-
`tation. With time, DNQ PAC can fall out of solution, especially at high temperatures.
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`O 2007 by Taylor & Francis Group, LLC
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`590
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`Microlittto grnphy : S cience nnd Technolo gy
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`These crystallized precipitates most readily forrn with high levels of DNQ' In addition,
`resist paiticulate levels can be increased by the formation of gel particles, a result of acid-
`rndrrcôd novolac cross-linking via thermal decomposition of DNQ. Any of these routes to
`particulate formation can leaã to levels exceeding that measured by the resist manufac-
`irrrur. Because of this, point-of-use filtration has become common practice for most
`production applications to ensure photoresist consistency [6J. Resist materials are
`èornrnonly filte?ed at a level of approximately 25% of the minimum geometry size. As
`the geom'etry size approaches sub -0.35 ¡rm,