focused ion beam - cime | epfl · pdf filemse-603 doctoral school 2009 fib marco cantoni 2 ......

MSE-603 doctoral school 2009 FIB Marco Cantoni 1

12. FIB12. FIB

Marco Cantoni, 021/693.48.16

Centre Interdisciplinaire de Microscopie Electronique

CIME


Focused Ion BeamFocused Ion Beam

a) Principles

How does it work..?

Ion source, optics, interaction with the sample

b) Basic Application

Imaging, milling, deposition, typical applications

c) TEM sample preparation, examples

d) FIB Nanotomography, 3D microscopy


FIB @ CIME

NVISION 40 from CARL ZEISS

Dual Beam = SEM + FIBDual Beam = SEM + FIB

SEM: Schottky thermal field emitter

FIB: Ga LMIS

4 Gas Injector Systems

– Pt deposition (C9H16Pt)

– C deposition

– SiO2 deposition (TEOS)

– Insulator Enhanced Etch (XeF2)

– Selective Carbon Mill (MgSO4)

2 Kleindiek Micromanipulator (in situ TEM lamella lift out)

Since July 2008


Focused Ion BeamMainly developed in 1970’s and 80’s (Escovitz, Levi-Setti, Orloff, Swanson…)Ion column structure similar to that of SEMSource: Liquid Metal Ion Source (LMIS).Ex: Ga, Au, Be, Si, Pd,B, P, As, Ni, Sb,alloys …Principle:A strong electromagneticfield causes the emissionof positively charged ions

Schematic diagram of a FIB ion columnSource: IBM Almaden Research Center

SIM = SIM = ScanningScanning Ion Ion MicroscopeMicroscope


Why use ions instead of electrons?

ElectronsElectronsare very smallinner shell reactionsHigh penetration depthLow mass -> higher speed for given energyElectrons are negativeMagnetic lens (Lorentz force)

IonsIonsBig->outer shell reactions (no x-rays)High interaction probabilityless penetration depthIons can remain trapped -> dopingHigh mass -> slow speed but high momentum milling !!!Ions are positiveElectrostatic lenses

Why Gallium ?

Ga is metallic, low melting point, in the middle of the periodic table, no overlap with other elements in EDX


comparison FIB SEM Ratio Particle type Ga+ ion electron elementary charge +1 -1 particle size 0.2 nm 0.00001 nm 20’000 mass 1.2 .10-25 kg 9.1.10-31 kg 130’000 velocity at 30 kV 2.8.105 m/s 1.0 108 m/s 0.0028 velocity at 2 kV 7.3.104 m/s 2.6.107 m/s 0.0028 momentum at 30 kV 3.4.10-20 kgm/s 9.1.10-23 kgm/s 370 momentum at 2 kV 8.8.10-21 kgm/s 2.4.10-23 kgm/s 370 Beam size nm range nm range energy up to 30 kV up to 30 kV current pA to nA range pA to uA range Penetration depth In polymer at 30 kV 60 nm 12000 nm In polymer at 2 kV 12 nm 100 nm In iron at 30 kV 20 nm 1800 nm In iron at 2 kV 4 nm 25 nm

secondary electrons 100 - 200 50 - 75 Average electrons signal per 100 particles at 20 kV

back scattered electron

0 30 - 50

substrate atom 500 0 secondary ion 30 0 x-ray 0 0.7


Ion Solid interaction

• Sputtering

• Damage

• Implantation• Secondary electron

emission (SE-image)2-3 SE per Ion !

• Surface chemical reactions- deposition- enhanced etching


3 basic “operating modes”

Emission of secondary ions and electrons– FIB imagingimaging a)low ion current

Sputtering of substrate atoms– FIB millingmilling b)high ion current

Chemical interactions (gas assisted)– FIB depositiondeposition– Enhanced (preferrential) etchingetching c)

Other effects:Ion implantationDisplacement of atoms in the solid

– Induced damageEmission of phonons

– Heating

ion beam

Ion beam

Ion beam

secondary e

secondary isubstrate

sputtered materialfrom substrate

deposited film

volatile products

precursormolecules

c)

b)

a)

substrate

substrate


Imaging30kV Electrons vs Ga Ions

BSEBSE SE-2SE-1

Monte-Carlo Simulation casino v2.42http://www.gel.usherbrooke.ca/casino/download2.html

SRIM 2006http://www.srim.org/


SE image contrast

e-beam 5kVion-beam 30kV 50pA

material (sputtering) contrastorientational contrast


Channeling contrast

Atom columns align with the ion trajectory = higher penetration-> less sputtering and less SE electrons

Secondary Electron Emission Coefficient vs. Angle, (100) Copper 30 keVAr Ions

G. Carter and J.S. Colligan, Ion Bombardment of Solids, (Elsevier 1968)


MillingMaterial Sputterrate

[µm³/nC]

Si 0.27Thermal Oxide 0.24TEOS 0.24Al 0.3Al2O3 0.08GaAs 0.61InP 1.2Au 1.5TiN 0.15Si3N4 0.2C 0.18Ti 0.37Cr 0.1Fe 0.29Ni 0.14Cu 0.25Mo 0.12Ta 0.32W 0.12MgO 0.15TiO 0.15Fe2O3 0.25Pt 0.23PMMA 0.4PZT-high aspect ratio „capacitor“, W. Adachi (EPFL-LC)


X.XuX.Xu, et. al., et. al.

J. Vac. Sci. Technol. B, J. Vac. Sci. Technol. B, 10, 2675 (1992) 10, 2675 (1992)

Ion-Solid interactionSputtering Yield

φ

Sputtering yield depends on incident angle φ

Higher probability of collision cascades near the surface at higher φ

Sputtering yield has maximum for φ = 75


MillingX.XuX.Xu, et. al., et. al.

J. Vac. Sci. J. Vac. Sci. Technol. B, Technol. B, 10, 2675 10, 2675 (1992) (1992)

FIB milling of steel

φ


Polishing,at shallow angles

X.XuX.Xu, et. al., et. al.

J. Vac. Sci. J. Vac. Sci. Technol. B, Technol. B, 10, 2675 10, 2675 (1992) (1992)


Gas assisted deposition

substrate

adsorbedmolecules

ion beam(e beam)


Nanofabricated structures

Coil 700nm pitch, 80nm line width, diamond-like amorphous carbon, FIB induced CVD

Shinji Matsui, et.al.J. Vac. Sci. TechnolB18, 3181(Nov/Dec, 2000)(HimejiInstitute of Technology,Hyogo, Japan)

+ ++

++++ +

+

++++ +

+

++++


Courtesy MatsuiCourtesy Matsui

11μμmm

33μμmm


b) Basic Applications“Industrial” applications (semiconductor industry)sectioning for failure analysisprototype circuit rewiringmask repairTEM sample preparation

ResearchMicromachiningNanofabricated structuresTEM sample preparation


Applications Chip Modification

Insertion of electrical connection: 1) Removal of isolating layer (milling)

2) Pt deposition (FIB deposition)

M. M. PaviusPavius CMICMI


FIB-manufactured AFM-tips


Failure analysis

FIB cross-sectioning and SEM imaging


Prethinned sample on TEM-«grid »

Rough milling at high currents

filling of voids Nb3Sn superconductorP-Y. Pfyrter (diploma work)

Pre-thinned (H-bar)


2 windows method

DFDF--STEMSTEM


c) TEM preparationin-situ lift-out movie

(downloaded from http://www.feicompany.com/


micro-gripper


Si nano-wireM. Pavius, V. Pott, CMI


TEM, HRTEM

5nm5nm

Si

SiO2 amorph

poly-silicon


TEM lamellae by FIB

Large (10x5um) flat areas with uniform thickness (50-80 nm)Preparation of heterogeneous samples with “difficult” material

combinations becomes possiblePrecise selection of the lamella position possible (devices)

Focused Ion Beam adds a new dimensionFocused Ion Beam adds a new dimensionto TEM specimen preparationto TEM specimen preparation

Take care of artifacts !!!


Amorphizationuse low-kV cleaning

Ga 30keV

Ga 5keV

Ga 1keV

Cry

stal

line

Cry

stal

line

Am

orph

ous

Am

orph

ous

Am

orph

ous

Am

orph

ous

25-30nm 25-30nm

5-7nm

2-3 nmtypical values for Si

Alternative:low energy Ar Ion

milling

amorphized layer


3D Microscopy3D Microscopy


d) FIB Nanotomography3D Microscopy


Problem of serial sectioning: 3D-reconstruction of disordered microstructures

?? Nr of particles ???? Shape ??

3D

From: J.C.Russ, 1998

2D Volume fraction


Voxel, Resolution, Pixel size


3D slicing of multifilamentNb3Sn superconductor


Preparing for slicing

the end AutomatedAutomated millingmilling and and imagingimaging of 170 slices (10h)of 170 slices (10h)


align and crop

http://rsb.info.nih.gov/ij/index.html


3D volume rendering, reconstruction:

Orthogonal slices

3D volume 3D volume renderingrendering, reconstruction:, reconstruction:

Orthogonal slicesOrthogonal slices

Coronal sliceCoronal slice

Sagittal sliceSagittal slice


The choice of the right detector

SE detector (TLD)SE detector (TLD) BSE detector (TLD)BSE detector (TLD)

Ion beam imaging (SE)

Ion beam for slicing and imaging requires stage movement…!


Image nr. 150

Image nr. 141

Area of image data usedfor 3D reconstruction

149 148 147 146

145 144 143 142

x

y

z

5 µm

Quantitative microstructure analysisAlgorithms

object recognitionstereological correction of boundary truncation

extraction of statistical data (particle shape and size distribution)


Particle recognition:Edge detection in 3D,

Watershed for separation

Voxel:75nm

Cube:40*20*15 m

Size, 3D-shape, geometrical relationships between particles


Cube size: 23.5x19.2x9.5 m / Voxel size: 29.69x37.67x60 nm / Nr. of particles: 2236 (total), 1404 (inside)

Grain size fraction 3

Quantitative microstructure analysis Algorithms

Münch and Holzer 2006J.Amer.Ceram.Soc.

FIB-nt of particulate systems – part II:Object recognition and

effect of boundary truncation


Echantillons biologiques….

Graham Knott UNIL / CIME


FIB-NT compared with other 3D-techniques

3D

2D

From: Uchic, Holzer and InksonMat. Res. Bul., subm.

New possibilities in 3D-microscopy:Combination of FIB-ntwith Cryo, EBSD, EDX


Focused Ion Beamadds a new dimension to electron microscopy

SEM goes 3D– from 2D characterization and topography imaging to 3D volume analysis

TEM preparation– « impossible » samples can now be prepared (heterogeneous samples)– location of the transparent area can be selected with nm precision– Parallel surfaces (uniform thickness) ideally for AEM


Bonus


The future of scanning (electron) microscopy…?

An Introduction to Helium Ion Microscopy and its Nanotechnology Applications

John A. Notte*, Lou Farkas, Raymond Hill, Bill Ward*ALIS Corporation, 10 Technology Drive, Peabody, MA 01960, USA,

[email protected]

Microscopy today (2006)


The principle: field ion microscope as a source

Pyramidal tip

round tip


30kV Electrons vs He Ions


5kV Electrons vs 30kV He


(top) Secondary electron SEM image of alignment cross.(bottom) Secondary electron ALIS image of same alignment cross

•• smallsmall interaction volume for SEinteraction volume for SE--II

•• almostalmost no SEno SE--IIII

•• highhigh SESE--YieldYield ((currentscurrents in the in the fAfA--pApA range)range)

•• SESE--YieldYield dependsdepends on on atomicatomicnumbernumber z, z, materialmaterial contrastcontrast


Rutherford back-scattered ions

(left) Secondary electron image of a solder bump showing topography, but not much material difference.(right) RBI image of same solder bump clearly showing the differencebetween areas of tin (dark) and lead(bright).

Laser shot on coated material

SESE RBIRBI

SESE RBIRBI

RBI are not affected by charging effects

focused ion beam - cime | epfl · pdf filemse-603 doctoral school 2009 fib marco cantoni 2 ......

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