7. advanced SEM low kV imaging 14 MSE-602 2013 advanced SEM Marco Cantoni Nb 0.5 mm 3Sn multifilament superconducting cable Nb3Sn superconductor multifilament cable: 14’000 Nb3Sn

MSE-602 2013 advanced SEM Marco Cantoni

7. advanced SEM

SEM• Low voltage SE imaging

• Condition of the surface, coatings, plasma cleaning

• Low voltage BSE imaging

• Polishing for BSE, EDX and EBSD, effect of ion beam

etching/polishing

1


100

50

10

5

10.5 1 2 5 10 20 30

FE LaB6

W

Tension d'accélération (kV)

Rés

olut

ion

(nm

)

Basse tension/haute résolution: - observation de la surface réelle - échantillons non-métallisés - faible endommagement dû au faisceau

Haute tension/haute résolution: - effets de bord - détails fins non-résolus - fort endommagement dû au faisceau

1985

2010

Field emission gun monochromatorsbeam boosters, beam deceleration,Lens-design: In-lens, Semi-in-lens, immersion lensShort working distance

Detectors:Everhard-Thornley (SE)In-column (through the lens, in-lens, “in-beam”)Low Voltage BSE detection, energy filtering (separation of materials and topography contrast)

Analytical SEM:SDD EDX detectors (high throughput, large collection angle)High-speed EBSD detectorsBeam currents of several 100 nA

Latest generation of SEM

High voltage,high resolution:• Edge effects• Charging effects• Beam damage

low voltage, high resolution:• Observation of the “real” surface• Non-metallic samples• Reduced beam damage

2


SEM low kV imaging

No specimen preparation needed:Low kV imaging of non-conducting, low density samples

FEI MagellanOperator: Ingo GestmannSamples: Marco Cantoni

Al2O3 Nano-crystals

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SEM low kV imaging

No specimen preparation needed:Low kV imaging of non-conducting, low density samples

FEI MagellanOperator: Ingo GestmannSamples: Marco Cantoni

Carbon nano-tubes(MWCT)

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SEM low kV imaging

No specimen preparation needed:Low kV imaging of non-conducting samples

Liquid filledorganic membranes

Zeiss Nvision 40Marco Cantoni

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SEM low kV imaging

No specimen preparation needed:Low kV imaging of non-conducting samples

Liquid filledorganic membranes

Zeiss Nvision 40Marco Cantoni

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SEM low kV imaging

Purely organic specimen: non-conductive, low density:Metal coating

HeLa Cells, Graham KnottMarco Cantoni, Nvision 40

15nm Ag/Pd coating

3nm Os coating3nm Os coating

7


SEM low kV imaging

“Easy” sample:

SC wireNb3Sn in Cu matrix

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SEM low kV imaging

“Easy” samples: Everhard-Thornleydetector (SE)

Solid state BSEdetector

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SEM low kV BSE imaging

Solid state BSEdetector

2keV, In-ColumnEsB detector

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SEM low kV imaging “Easy” samples:

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12



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Contamination by hydro-carbons

• contamination “spoils” imaging at low kV

• How to avoid (at CIME):– plasma cleaning of the sample before

inserting– Plasma clean the chamber at each

insertion (multi-user environment)

XL30 FEG & EVACTRON

NVision40 & EVACTRON

SEM low kV imaging

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0.5 mmNb3Sn multifilament superconducting cable

Nb3Sn superconductor multifilament cable:14’000 Nb3Sn filaments (diameter ~5um) in bronze matrix

SEM: Preparation for analytical EM

Solid State BSE detector20kV acceleration voltage

Mechanical polishing <-> Ar ion beam polished

EDX maps

Sn

Cu

Nb

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Mechanical polishing:• Grains of harder phase

incorporated in softer matrix• Deformed microstructure at

surface reduces formation of Kikichi lines in EBSD

SEM BSE/EDX/EBSD

After Ar ion polishing (Gatan PIPS)

Sn

Cu

Nb

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in-chamberET-detectorSE

in-column“InLens”SE-detector

in-column, “energy-selective” EsBBSE-detector

Ion polishing

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Nb3Sn multifilament Superconductors

Materials & orientation contrast

SEM low kV BSE imaging

NVision 401.8kV EsB detector5µm

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Nb3Sn multifilament Superconductors

Materials & orientation contrast

FIB/SEM low kV BSE imaging

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Goal of final polishing:Removal of the damaged surface layermechano-chemical polishing (EBSD) or ion polishing

Interaction volumeBlue: scattered electronsRed: backscattered electrons (leaving the sample surface)

Monte-Carlo Simulation CASINO v2.42

escape depth of BSE: Nb3Sn 30kV: 800nm

5kV: 50nm

1kV: < 5nm

SEM preparation: polishing

1kV5kV

30kV

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New HR-SEM at CIME

• Starting point: XL-30 SFEG SIRION (since 2001)• First semi-in-lens HR-SEM:

in-lens (through the lens) detection of SE and BSE

Resolution in UHR mode: 1.5 nm at 10 kV (or higher); 2.5 nm at 1 kV

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MSE-602 2013 advanced SEM Marco Cantoni 22



Best “SEM” at EPFL: FIB Nvision@CIME

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Two different contrasts with one scan: parallel detectors

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Introducing...MERLIN™– Analytical power for the sub-nanometer world –

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Double condenser lens Aperture independent probe current adjustment

Beam Booster Brightness of the electron probe

maintained for low landing energies

MERLIN™– Analytical power for the sub-nanometer world –

Proven GEMINI® final lens design New double condenser lens for highest

probe current possibilities (300 nA) Beam booster technology maintains

brightness of all electron probes including low landing energies

True on-axis in-lens SE and BSE detectors

► GEMINI® II designComplete detection

system

High stability field emitter cathode Maximum probe current 300 nA

Energy selective Backscatter detector (EsB)

In-lens Secondary Electron detector

GEMINI® II final lens

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In-lens SE(Secondary Electrondetector)

Topographical informationwith on-axis in-lens SE detector


GEMINI® II design► Complete detection

system

Complete detection system: Unique double in-lens detection Acquisition of pure secondary and

backscatter electron signals Separation of compositional, topographical

and crystalline surface information

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EsB(Energy selective Backscatter detector)

Energy filtering grid

Si

Si3N4

TiN

Ti

Compositional contrastwith on-axis in column EsB detector


Complete detection system: Unique double in-lens detection Acquisition of pure secondary and

backscatter electron signals Separation of compositional, topographical

and crystalline surface information

GEMINI® II design► Complete detection

system

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Sapphire

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Documents

7. advanced SEM low kV imaging 14 MSE-602 2013 advanced SEM Marco Cantoni Nb 0.5 mm 3Sn multifilament superconducting cable Nb3Sn superconductor multifilament cable: 14’000 Nb3Sn