Copper Electrodeposition for Nanofabrication of Electronics Devices PDF
Preview Copper Electrodeposition for Nanofabrication of Electronics Devices
Nanostructure Science and Technology Series Editor: David J. Lockwood Kazuo Kondo Rohan N. Akolkar Dale P. Barkey Masayuki Yokoi E ditors Copper Electrodeposition for Nanofabrication of Electronics Devices Nanostructure Science and Technology Volume 171 Series editor David J. Lockwood, Ottawa, Canada For furthervolumes: http://www.springer.com/series/6331 Kazuo Kondo Rohan N. Akolkar • Dale P. Barkey Masayuki Yokoi • Editors Copper Electrodeposition for Nanofabrication of Electronics Devices 123 Editors KazuoKondo DaleP. Barkey Department of Chemical Engineering Department of Chemical Engineering Osaka Prefecture University Universityof New Hampshire Osaka Durham,NH Japan USA RohanN.Akolkar Masayuki Yokoi IntelCorporation Industrial TechnologySupportInstitute Hillsboro,OR Osaka USA Japan ISSN 1571-5744 ISSN 2197-7976 (electronic) ISBN 978-1-4614-9175-0 ISBN 978-1-4614-9176-7 (eBook) DOI 10.1007/978-1-4614-9176-7 Springer New YorkHeidelberg Dordrecht London LibraryofCongressControlNumber:2013954032 (cid:2)SpringerScience+BusinessMediaNewYork2014 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpartof the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation,broadcasting,reproductiononmicrofilmsorinanyotherphysicalway,andtransmissionor informationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purposeofbeingenteredandexecutedonacomputersystem,forexclusiveusebythepurchaserofthe work. Duplication of this publication or parts thereof is permitted only under the provisions of theCopyright Law of the Publisher’s location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the CopyrightClearanceCenter.ViolationsareliabletoprosecutionundertherespectiveCopyrightLaw. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publicationdoesnotimply,evenintheabsenceofaspecificstatement,thatsuchnamesareexempt fromtherelevantprotectivelawsandregulationsandthereforefreeforgeneraluse. While the advice and information in this book are believed to be true and accurate at the date of publication,neithertheauthorsnortheeditorsnorthepublishercanacceptanylegalresponsibilityfor anyerrorsoromissionsthatmaybemade.Thepublishermakesnowarranty,expressorimplied,with respecttothematerialcontainedherein. Printedonacid-freepaper SpringerispartofSpringerScience+BusinessMedia(www.springer.com) Preface Copper has lower resistivity than aluminum and can be electrodeposited easily. Hence,coppercanbeusedforchipwiring.In1998,thecopperdamasceneon-chip interconnect process was introduced commercially and became the first industrial nanofabrication process. This nanofabrication technology relies on electrodepos- ition of copper to fill cavities or vias of diameters less than 0.1 lm. This process hasnowbeen adopted worldwideforadvancedsemiconductormanufacturingand has branched into several industrial applications: Damascene metallization, through-silicon via metallization, interstitial via hole build-up in printed wiring boards, and both sides smooth Cu foils for collectors in Li-ion batteries. However, no comprehensive books have been published on Copper Electro- depositionforNanofabrication.ThePartIofpresentbookintroducesthereaderto fundamental aspects of copper electrodeposition. This is followed by details of additive chemistry, suppression effects (due to PEG additive), and acceleration effects(duetoSPSadditive),leadingtofillingmechanisms.Mathematicalmodels forsuperfilling,continuummodelsfornucleationandgrowth,KineticMonteCarlo simulations, and shape evolution are then reviewed. ThePartIIofthebookcoverstwospecificchallengesfacingnano-interconnect fabrication in the coming decade, i.e., direct electrodeposition on noble metal barriers and liners and microstructure evolution in electrodeposited Cu nanowires and its impact on Cu resistivity. The part starts with a critical overview of the specific scalingchallenges foreseen indamascene interconnectfabrication. It also outlines the current challenges to the two technologies, such as direct plating, electroless deposition, and theory-guided molecular design of additives in elec- trochemical systems. This introductory chapter is followed by a comprehensive study that discusses the evolution of microstructure in electrodeposited Cu nano- interconnects. A hallmark of this study is the development of metrology tech- niques (SIMS) to probe patterned metal lines. Finally, the part ends with a con- tribution documenting mechanisms involved in direct plating of Cu on noble metals such as ruthenium (Ru). InPartIIIofthisbook,emergingapplicationsofelectrodepositionareoutlined: through-siliconvias(TSVs),printedwiringboards,copperfoilsfor Li-ion battery current collectors, and through-hole filling. TSVs are used for fast conduction of digital signals from one chip to another chip in advanced packaging solutions in smartphones,highspeedimageprocessing,andcapsuleendoscopes.Ininterstitial v vi Preface via hole build-up printed wiring boards, the interstitial via holes are filled by copperelectrodeposition.Then,theindividualboardlayersarepiledupsothatthe via holes interstitially connect the wiring in the vertical direction. The primary application of this technology recently has been in smart phones. Smooth copper foils serve as electric collectors for the anode of Li-ion batteries. In order to coat thecarbononbothsidesofthecopperfoil,thefoilmustbesmoothandthuscoated with electrodeposited copper. Through-hole plating is an emerging technology in printed wiring board manufacturing. Kazuo Kondo was very much astonished when he visited the IBM Watson Research Center in 1999 and Drs. M. Datta and J. Dukovic kindly showed him theirlabandredcopperwaferelectrodepositedbycopper.Drs.DattaandDukovic are team members for the development of the damascene on-chip semiconductor wiring process. This experience gave Kazuo Kondo the initial motivation to start research in copper electrodeposition. Wehopethatthisbookbenefitsscientists,engineers,andacademiciansworking in the field of copper electrodeposition. We are gratefulto all the contributors for theirtime,commitment,patience,andfeedback.Throughourinteractionswiththe contributors,wehavelearnedagreatdeal.Wesincerelyhopethereadersenjoythe chapters.Finally,wewouldliketoacknowledgetheopportunitygiventousbyK. Howell of Springer to edit this book. Kazuo Kondo Rohan N. Akolkar Dale P. Barkey Masayuki Yokoi Contents Part I Copper Electrodepositon and Additive Chemistry 1 Copper Electrodepositon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Masayuki Yokoi 2 Supression Effect and Additive Chemistry. . . . . . . . . . . . . . . . . . 27 Masayuki Yokoi 3 Acceleration Effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 Dale P. Barkey 4 Modeling and Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Yutaka Kaneko Part II Copper on Chip Metallization 5 Frontiers of Cu Electrodeposition and Electroless Plating for On-chip Interconnects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 James F. Rohan and Damien Thompson 6 Microstructure Evolution of Copper in Nanoscale Interconnect Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 James Kelly, Christopher Parks, James Demarest, Juntao Li and Christopher Penny 7 Direct Copper Plating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 Aleksandar Radisic and Philippe M. Vereecken Part III Through Silicon Via and Other Methods 8 Through Silicon Via. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 Kazuo Kondo vii viii Contents 9 Build-up Printed Wiring Boards (Build-up PWBs). . . . . . . . . . . . 193 Kiyoshi Takagi and Toshikazu Okubo 10 Copper Foil Smooth on Both Sides for Lithium-Ion Battery. . . . . 229 Akitoshi Suzuki and Jun Shinozaki 11 Through Hole Plating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267 Wei-Ping Dow Eratum to: Acceleration Effect . . . . . . . . . . . . . . . . . . . . . . . . . E1 Dale P. Barkey Part I Copper Electrodepositon and Additive Chemistry Chapter 1 Copper Electrodepositon Masayuki Yokoi 1.1 Functions of Primary Constituents Copper sulfate (CuSO (cid:2)5H O) and sulfuric acid (H SO ) are the primary 4 2 2 4 constituents of the acid copper sulfate bath [1]. The formulation of the bath is adjusted depending on the intended use, as given in Table 1.1. For conventional copper deposition such as decorative plating, electroforming, copper refining, high copper sulfate concentration, and low sulfuric acid concen- tration baths have long been adopted. Their formulations are determined on the basis of whether the bath voltage is low and the current efficiency of copper deposition is high, in terms of energy cost, important in large-scale copper deposition manufacturing such as electroforming, refining, decorative plating for automobiles, and so on. For printed wiring board and through-hole plating, a low copper-high sulfuric acid baths were developed for high macro-throwing power bath in the 1980s, and were used widely for achieving uniform copper deposition onlarge areacircuitboardsandinside thethrough-holes sub-mmorder insize. In recent years, since the Copper damascene process was created in 1997, both constituent concentrations are adjusted to relatively low copper sulfate-high sul- furicacidbathforthepurposeofbottom-upfillingofvia/trenchofnanometersize in semiconductor interconnect technology. In printed wiring board and through-hole plating, macro-throwing power, the most important property to be expected, is drastically improved by decreasing copperconcentrationandincreasingsulfuricacidconcentration.Asiswellknown, macro-throwing power was defined as the product of specific conductivity of the solution (j) and the derivative of surface overpotential with respect to current density ðdg=diÞ by Carl Wagner [2]. M.Yokoi(&) OsakaPrefectureUniversity,Osaka,Japan e-mail:[email protected] K.Kondoetal.(eds.),CopperElectrodepositionforNanofabricationofElectronicsDevices, 3 NanostructureScienceandTechnology171,DOI:10.1007/978-1-4614-9176-7_1, (cid:2)SpringerScience+BusinessMediaNewYork2014
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