Pulsed Laser Ablation of Solids: Basics, Theory and Applications

241 Pages·2014·8.567 MB·English

by  Mihai Stafe, Aurelian Marcu, Niculae N. Puscas (auth.)

Springer Series in Surface Sciences 53
Mihai Stafe
Aurelian Marcu
Niculae N. Puscas
Pulsed Laser
Ablation of Solids
Basics, Theory and Applications
Springer Series in Surface Sciences
Volume 53
Series Editors
Gerhard Ertl, Berlin, Germany
Hans Lüth, Jülich, Germany
Douglas L. Mills, Irvine, USA
For furthervolumes:
http://www.springer.com/series/409
Thisseriescoversthewholespectrumofsurfacesciences,includingstructureand
dynamicsofcleanandadsorbate-coveredsurfaces,thinfilms,basicsurfaceeffects,
analytical methods and also the physics and chemistry of interfaces. Written by
leadingresearchersinthefield,thebooksareintendedprimarilyforresearchersin
academia and industry and for graduate students.
Mihai Stafe Aurelian Marcu
•
Niculae N. Puscas
Pulsed Laser Ablation
of Solids
Basics, Theory and Applications
123
Mihai Stafe Aurelian Marcu
Niculae N.Puscas Laser Department
Department of Physics National InstituteforLaser Plasma and
UniversityPolitehnica of Bucharest Radiation Physics
Bucharest Bucharest-Magurele
Romania Romania
ISSN 0931-5195
ISBN 978-3-642-40977-6 ISBN 978-3-642-40978-3 (eBook)
DOI 10.1007/978-3-642-40978-3
SpringerHeidelbergNewYorkDordrechtLondon
LibraryofCongressControlNumber:2013949439
(cid:2)Springer-VerlagBerlinHeidelberg2014
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
Soon after its experimental realization, the laser was used in several practical
applications. One of the most important applications of lasers are related to the
laser ablation of solids because they offer very important advantages over the
classicaltools,includingchoiceofwavelengthandpulsewidthtomatchthetarget
material properties as well as one-step direct and locally confined structural
modification. Also, using lasers it is possible to reduce the thermo-mechanical
damage and to facilitate heterogeneous integration of the components into func-
tionaldevices.Theabovementionedadvantagesareveryimportantincaseswhere
conventional thermo-chemo-mechanical treatment processes are ineffective.
The microfabrication ofseveral componentswith basic dimensions inthe few-
microns range via laser irradiation has been implemented successfully in the
industrial environment. Beyond this, there is an increasing need to advance the
science and technology of laser processing to the nanoscale regime.
This book aims at providing young researchers and graduate students with a
comprehensive review of progress and the state of the art in the pulsed laser
ablation(PLA)fieldlinkingfundamentalphenomenawithrecentapplications.The
bookintroducestheresearchersintothefieldofPulsedLaserAblationofSolidsby
synthesizing the state-of-the-art of the pulsed laser ablation processes and its
applications. The understanding of the evolution of the energy coupling with the
target and the induced phase-change transformations plays an important role for
improving the quality of the material processing.
Thecontentofthebookisbasedonrecentresearchstudiesofdifferentgroupsand
includes the authors’ contribution on pulsed laser ablation. In the introductory
chapter,severalconsiderationsconcerningthetools,whichareusedforlaserabla-
tionofsolidmaterials(metals,semiconductors,dielectrics)arepresented,pointing
outthemajorroleofthematerialprocessingusinglasersascomparedtoclassical
tools.Also,somepracticalapplicationsofPLAandgeneralaimsareemphasized.
In Chap. 2 several lasers for pulsed laser ablation like: Nd-YAG laser,
Ti-sapphire laser, excimer laser, CO laser are analyzed concerning the mode
2
operation (pulsed, CW, tunable), pulse duration (nano, pico, femtosecond range),
power and operation wavelength (from near UV to far IR range), emphasizing
their best capabilities. Also, the Q-switched and mode locked lasers are analyzed
v
vi Preface
together with the most used methods for their practical operation: mechanical,
electro-optical, acousto-optical, methods with saturable absorbers and thin films,
etc. The knowledge of the laser operation and the parameters is used to control
PLA process for different types of solid materials in different ambient conditions.
Attheendofthischapterseveralcombinedirradiationmethodsinthefarandnear
field (i.e., direct irradiation and projection through masks and microlens array,
laser trepanning, andlaser lithography),andsomeeffects ofpulsedurationonthe
ablation rate are discussed.
TheChap. 3isdevotedtothelaser-matterinteractionbelowtheplasmaignition
threshold intensity. The basic linear and non-linear phenomena involved in laser-
matter interaction at high intensities: harmonic generation, self focusing, self
guiding, absorption and ionization, two-photon absorption, stimulated Raman
Effectarecharacterizedfromtheoreticalandexperimentalpointofview.Also,the
mostimportantexperimentalmethodsforanalyzingthemainphenomenainvolved
inlaser-matterinteractionduringPLAbelowtheplasmaignitionthresholdsuchas
reflectometry and analysis of thermal radiation are discussed. The physics of the
ablation process is complex, given that it involves laser-solid interactions, the
vapor/plasmaformationandexpansion,andthelaser-vaporinteraction.Thephase
and/or structural changes induced on the target by the laser radiation can be
detected by means of the time-resolved reflectivity (TRR) method, while the
thermal changes can be detected by rapid infrared pyrometry (RIP) systems. The
coupling of the two methods (RIP and TRR) allows the study of the melting
kinetics induced by laser radiation in a large number of bulk metallic, dielectric,
and semi-conductor materials. The plasma spectroscopy methods were developed
over the past decades and they provide basic data which are needed for the
implementation of many of the experimental methods, and to descriptions of
instrumentation. A detailed study of the basic mechanisms involved in laser
ablation below the plasma ignition threshold is performed at the end of this
chapter.
The laser-matter interaction above the plasma ignition threshold intensity is
presented in the Chap. 4 of this book. At the beginning of this chapter the main
phenomena involved in production of the ablation plasma and in laser-plasma
interaction during PLA are analysed: plasma heating, critical density, plasma
shielding, ablation plume expansion, several types of collisions, etc. Also, in this
chapterseveralexperimentalmethodsforanalyzingthemainphenomenainvolved
in laser-plasma interaction are presented in detail: optical methods (interfero-
metric, Thomson-scattering, spectrometric methods, laser induced fluorescence
(LIF) spectroscopy), mass spectroscopy, high speed imaging, etc.
The Chap. 5 of the book is devoted to the material removal and deposition by
PLA and associated phenomena: micro and nano-processing (patterning) of
materials by PLA, material removal in gaseous and liquid etchants, nanoparticle
production, pulsed laser deposition and ablation, plume filtering, etc.
In Chap. 6, we present several experimental techniques for analyzing the
material removal and deposition rates in real time: opto-acoustics and
Preface vii
interferometricmethods,emission spectroscopyoftheablationplasmaandquartz
microbalances.
The conclusions of the work are outlined in the last chapter of this book.
TheAuthorswishtothankseveralpeoplewhoinfluencedtheirworkinthefield
of lasers and laser-mater interaction. Thus, Mihai Stafe wishes to thank to Prof.
I.M.PopescuwhosupervisedhisPh.D.workinthefiledofPulsedLaserAblation
at Department of Physics at University ‘Politehnica’ of Bucharest, Romania. He
also wants to thank to Prof. I. Foldes and Prof. S. Szatmari for the supervision
during his postdoctoral studies on High Harmonics Generation on gas jets and
solid targets at HILL laser facility at Department of Experimental Physics of
University of Szeged, Hungary. Thanks will be also addressed to Prof. G. D.
Tsakiris and Prof. F. Krausz from Max-Planck Institute for Quantum-Optics at
Garching, Germany for the opportunity to work at LWS 10/20 facility on High
Harmonics Generation on solid targets at the relativistic limit.
NiculaePuscaswishestothankDr.N.Semmar,Dr.C.Leborgne,andDr.Jean-
Michel Pouvesle from GREMI, CNRS/Université d’Orléans, France for the
opportunity to work in their research group and for useful discussions.
AurelianMarcuwishestothankProf.I.M.Popescutoo,butalsoDr.Constantin
Grigoriu from National Institute for Laser Plasma and Radiation Physics from
Bucharest-Magurele (Romania) and K. Yatsui from Nagaoka University of
Technology, Nagaoka (Japan) who made possible part of the experimental work
presented in this book.
Bucharest, Romania Mihai Stafe
Aurelian Marcu
Niculae N. Puscas
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Short History: Classical Tools Versus Lasers Tools. . . . . . . . . . 2
1.2 Solid Materials (Metals, Semiconductors, Dielectrics)
to be Processed by PLA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.1 Thermally Well-Conducting Materials . . . . . . . . . . . . . 7
1.2.2 Wide-Bandgap Materials, Glasses, Polymers. . . . . . . . . 8
1.3 Practical Applications of PLA and General Aims . . . . . . . . . . . 8
1.3.1 PLD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.3.2 Cluster Formation by PLA . . . . . . . . . . . . . . . . . . . . . 9
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2 Lasers for Pulsed Laser Ablation . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1 CO , Nd-YAG, Ti–Sapphire, Excimers Lasers . . . . . . . . . . . . . 15
2
2.1.1 Nd-YAG Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.1.2 Ti-Sapphire Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.1.3 Excimer Laser. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.1.4 CO Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2
2.2 Nano, Pico, Femtosecond Lasers. Q-Switched
and Mode Locked Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.2.1 Nano, Pico, Femtosecond Lasers. . . . . . . . . . . . . . . . . 25
2.2.2 Q-Switched and Mode Locked Lasers . . . . . . . . . . . . . 28
2.3 Laser Parameters to be Controlled in PLA for Different
Types of Solid Materials in Different Ambient Conditions. . . . . 39
2.4 Basic Experimental Setup for PLA . . . . . . . . . . . . . . . . . . . . . 44
2.4.1 Combined Irradiation Methods . . . . . . . . . . . . . . . . . . 46
2.4.2 Projection Through Microlens Array . . . . . . . . . . . . . . 47
2.4.3 Laser Trepanning. . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
ix
x Contents
3 Laser-Matter Interaction Below the Plasma Ignition
Threshold Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.1 Linear and Non-linear Phenomena Involved
in Laser-Matter Interaction at High Intensities:
Harmonic Generation, Self Focusing, Self
Guiding, Absorption and Ionization. . . . . . . . . . . . . . . . . . . . . 54
3.1.1 Second Order Nonlinear Effects . . . . . . . . . . . . . . . . . 54
3.1.2 Third-Order Nonlinear Effects. . . . . . . . . . . . . . . . . . . 56
3.1.3 Photoionization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
3.2 Experimental Methods for Analyzing the Main Phenomena
Involved in Laser-Matter Interaction During PLA Below
the Plasma Ignition Threshold: Reflectometry, Analysis
of Thermal Radiation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.3 Theoretical Models for PLA Below the Plasma Ignition
Threshold. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3.3.1 Semi-Quantitative Analytical Models. . . . . . . . . . . . . . 67
3.3.2 Numerical Photo-Thermal Models for Short
Laser Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
4 Laser-Matter Interaction Above the Plasma Ignition
Threshold Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
4.1 Main Phenomena Involved in Production of the Ablation
Plasma and in Laser-Plasma Interaction During PLA:
Plasma Formation and Evolution. . . . . . . . . . . . . . . . . . . . . . . 78
4.1.1 Plasma Heating, Self Focusing, Critical Density,
Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.1.2 Ablation Plume Expansion . . . . . . . . . . . . . . . . . . . . . 82
4.1.3 Interaction of Plasma Plume with Obstacles . . . . . . . . . 93
4.2 Experimental Methods for Analyzing the Main Phenomena
Involved in Laser-Plasma Interaction: Optical and Mass
Spectroscopy, High Speed Imaging . . . . . . . . . . . . . . . . . . . . . 95
4.2.1 Interferometric Methods. . . . . . . . . . . . . . . . . . . . . . . 96
4.2.2 Thomson-Scattering. . . . . . . . . . . . . . . . . . . . . . . . . . 104
4.2.3 Spectrometric Methods. . . . . . . . . . . . . . . . . . . . . . . . 112
4.2.4 Laser Induce Fluorescence (LIF) Spectroscopy . . . . . . . 119
4.2.5 Mass Spectrometry (MS) . . . . . . . . . . . . . . . . . . . . . . 123
4.3 Theoretical Models for Plasma Mediated PLA . . . . . . . . . . . . . 129
4.3.1 Numerical Photo-Thermal Models. . . . . . . . . . . . . . . . 129
4.3.2 Numerical Photo-Thermal-Hydrodynamical Models
for Plume Expansion and Material Removal. . . . . . . . . 136
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138