Table Of ContentNanostructure 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
