Development of an advanced low energy focused ion beam system based on immersion optics [Elektronische Ressource] / vorgelegt von Michael Rauscher

Sujets

• Physik

Informations

• Publié par: eberhard_karls_universitat_tubingen
• Publié le: 01 janvier 2006
• Nombre de lectures: 19
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Development of an Advanced Low
Energy Focused Ion Beam System
Based on Immersion Optics
Dissertation
zur Erlangung des Grades eines Doktors
der Naturwissenschaften
der Fakult¨ at fur¨ Mathematik und Physik
der Eberhard-Karls-Universit¨ at zu Tubingen¨
vorgelegt von
Michael Rauscher
aus Hechingen
2006Tag der mundlic¨ hen Prufung:¨ 31.07.2006
Dekan: Prof. Dr. Peter Schmid
1. Berichterstatter: Prof. Dr. Erich Plies
2. Berichters Prof. Dr. Oliver EiblMeiner Großmutter Gretel Turk.¨Contents
I Introduction 1
1 Introduction 3
2 FIB Systems in TEM Sample Preparation 5
2.1 StateoftheartTEMsamplepreparation.............. 6
2.1.1 Conventionalsamplepreparation 6
2.1.2 FIBtechnique......................... 6
2.2 Useoflowenergyfocusedionbeamsystems........ 8
3 Low Energy Focused Ion Beam System Design 11
3.1 Operationmodes........................... 12
3.2 Systemswithtargetonground..... 13
3.3 Systemswithtargetonhighvoltage...... 19
II Numerical Simulation 27
4 Aberration-Optical Treatment 29
4.1 Fundamentals of the aberration approach.............. 29
4.2 Method ............................ 30
4.2.1 Quantificationoftheprobesize.... 30
4.2.2 Systemoptimisation...... 3
4.2.3 Software...... 34
4.3 Results............................. 36
4.3.1 Gunlens...... 36
4.3.2 Objectivelens.......... 38
4.3.3 In-lensscanning............. 40
4.3.4 Lensoptimisation................... 41
4.3.5 Summaryandoveralsystemperformance......... 43
5 Impact of Coulomb Interactions 45
5.1 CharacterisationofCoulombinteractions.............. 45
5.2 Previousstudiesonlowenergysystems........... 465.3 Method ................................ 48
5.3.1 Software.. 48
5.3.2 Quantificationoftheprobesize.... 49
5.3.3 Systemoptimisation...... 51
5.4 Results................................. 53
5.4.1 Overalsystemperformanceincludinginteractions. 53
5.4.2 Fullyoptimisedsystemperformance............. 54
III Experimental System 57
6 Liquid Metal Ion Sources 59
6.1 Proprietarysources.......................... 59
6.2 SourcesbytheFZRosendorf..... 60
7 Mechanical Design 61
7.1 SystemComponents ......................... 61
7.1.1 Gunlens............. 61
7.1.2 Isolationvalveandbeamlimitingaperture......... 65
7.1.3 Stigmatorandbeamalignmentunit......... 68
7.1.4 Linertubeandobjectivelens ................ 69
7.1.5 Scandeflector.......... 70
7.2 Testsetupdesignandpreliminaryexperiments........... 72
7.2.1 UHVtestsetup......... 72
7.2.2 HVtestsetup............... 73
8 Power Supply 77
8.1 Column supply . . ............... 7
8.2 Beamscanningandimageacquisition............ 79
9 Experimental results 81
9.1 Beamalignment................. 81
9.2 Measurements.............. 83
IV Summary and Outlook 87
10 Summary 89
11 Outlook 91List of Frequently Used Symbols and
Abbreviations
∆φ .............. potentialequivalenttoenergywidth,i.e. energywidth
divided by charge
∆E .............. energywidth(fullwidthathalfmaximum)
κ ,κ ............ gunlensimmersionratio,objectivelensimmersionratio
1 2
φ ................ ionkineticpotential,i.e. ionkineticenergydividedbycharge
d ................ probesize(general)
d ..... virtualsourcesize
v
d ............... probesizecontaining50%ofparticles
50
d .............. geometricimageofsource
geo
d .............. probesizecalculatedusingRPSalgorithm
RPS
I ................ beamcurrent
z ................ positionalongopticalaxis
z ,z ............. objectposition,imageposition
o i
J ............... source angular current density
Ω
E ................ beam energy
M ............... magnification
m ......... ion mass
q ................ ion charge
wd ... working distance
EHT ............. Everhart-Thornleydetector
FFLV ............ fieldfreelowvoltagemode
FFLV-R ......... fieldfreelowvoltagemodewithretardingobjectivelens
FIB .............. focusedionbeam
GND ............ groundpotential
HV ... highvacuum
LEFIB ........... lowenergyfocusedionbeam
LMIS ............ liquidmetalionsource
MBE ............ molecularbeamepitaxy
PMT ............ photomultipliertube
SE.... secondaryelectron(s)
SEM ............. scanningelectronmicroscope,scanningelectronmicroscopy
SI ................ secondaryion(s)TEM ............ transmissionelectronmicroscope,transmissionelectronmi-
croscopy
UHV ............ ultra-highvacuum
V.. boostervoltage,i.e. groundrelatedvoltageoflinertube
booster
VLV ............. verylowvoltagemodePart I
Introduction