For:• biomaterials• semiconductors• ceramics• polymers• forestry / pulp & paper

• catalysis• environmentalstudies

• minerals• metallurgy • and more

A core resource facility allowing researchers ready access to:

• state-of-the-art equipment • the related expertise

Providing:• surface analytical services• a means for collaborative research

Surface Interface Ontario

Why the surface?• Boundary layer between the solid at its interface with its environment

• Understanding this interface is of fundamental and practical importance to many disciplines.

Modern methods of surface analysis allow for very detailed characterisation of the surface.

•Elemental Information- type and quantification

•Chemical Information- surface chemistry and elemental state

•Distribution- both lateral and into the bulk

Spectroscopic Methods

x, y, z

rotn.

+ tilt

SOURCE ANALYSER

Penetration depthof 1 keV particles

Photons - 1000 nmElectrons - 2 nmIons - 1 nm

Thus either the source or analysed particle will usually include an electron or ion for surface specificity

Beam OutBeam In

Photons Electrons Ions

Photons FTIR

Laser Raman

X-RayFluorescence

EXAFS

XPSUV PhotoectronSpectroscopy

SEXAFS

Laser Mass

Spectroscopy

Electrons ElectronMicroprobe

EDAX

AugerTEM / SEM

LEED

EELS

Electron-induced IonDesorption

Ions IonMicroprobe

SIMSIon ScatteringSpectroscopy

RBS

Surface Science UnitCentre for Biomaterials• Established in 1989• Funded by OCMR• Precursor of SI-Ontario

XPS – Leybold MAX200• Dual anode (Mg/Al) Kα• Monochromatic Al Kα• Flood gun (ineffective) • Analysis area (defined by aperture)

– 200 µm, 500 µm, 1 mm2, 2 x 4 mm2, 4 x 7 mm2

• Ion gun – depth profiling/cleaning

X-ray Photoelectron Spectroscopy (XPS)[Also known as Electron Spectroscopy for Chemical Analysis]

Principles• Incident X-rays cause photo-emission of electrons from the surface - energy analysed

• Binding energies are characteristic of each element -can be used for identification

• Binding energy of a particular electron affected by the atom’s environment - chemical information via the “chemical shift”

Information• Elements Li and up, on both insulating and conducting samples

• 0.1 - 1 at.% detection limit, straight-forward quantification (to ±5%)

• “Chemical-shifts” – bonding information

• Surface specific (2 - 10 nm)

• Angle-resolved XPS - non-destructive depth information (to 10 nm)

• Ion sputtering - deeper depth profiles

• High spectral resolution with monochromatic source

• Mapping capabilities – when utilising small analysis spotEB = hν - EK + Φ

The binding energies are characteristic of each element

- use for elemental identification

- peak area allows quantification

Survey spectrum of dentin from a cow’s tooth C 1s spectrum of PMMA obtained using monochromatic Al KαX-rays

note 3:1:1 C ratio

Chemical information via the chemical shift – thus information on

- chemical bonding of the element

- its particular oxidation state- this is also quantifiable

Angle-Resolved XPS (ARXPS)Non-destructive depth information (to ~10 nm)

Surface selective modification of fluoropolymers by Al deposition

McKeown et al. Langmuir 7 (1991) 2146

IB = IB 0 (1 - exp ( - dB / λBB sinθ ))

IA = IA 0 exp ( - dB / λAB sinθ ))

Making use of: I = I 0 exp ( - d / λλλλ sinθθθθ )

Models can be built to estimate amount and type of coverage. Thus:

B

A

θ

A

B

dB

Or, for partial coverage:

IA = IA0 . [ (1-f) + f . exp ( -dB / λB sinθ ) ]

IB = f . IB0 . [ (1 - exp ( -dB / λB sinθ ) ]

Applying this to the previous example:Depth of modification – 3 nm, with 89% degree of modification (“coverage”)

More details on this in John Wolstenholme’s talk

Estimate of overlayer thickness0.2% 0.8 nm

1.0% 1.8 nm

HA

CHX

0.2%

1%

Can apply to films/coatings

Retention of Antibiotics on Surfaces

Chlorhexidene (CHX)0.2 and 1% solutions on hydroxyapatite (HA)

P – unique to substrate

N – unique to adsorbate

Sodhi et al. J. Dental Res. 71 (1992) 1493

• Assume uniform overlayer• ARXPS not performed since “rough”– meaningless to tilt

Sputter Depth Profiling – for thicker layers

Evaluating Sol-Gel Ceramic Thin Films for Metal Implant Applications : III. In Vitro Ageing of Sol-Gel Derived Zirconia Films on Ti6Al4V

P. B. Kirk et al, Applied Biomaterials (1999)

Sol-Gel zirconia films deposited on Ti6Al4V and aged in Hanks’balanced salt solution. Precipitate, predominately Calcium Phosphate, formed upon aging.

Ar+ ions used to sputter profile through coating.

Over 12 h for profile

Profile

O 1s in Zr region – note: energy scale not corrected for charging

Surface Interface OntarioDepartment of Chemical Engineering & Applied Chemistry

• 2002• Following successful a CFI application

ToF-SIMS – ION-TOF IV• Liquid Metal Ion Gun (Ga)• Dual Column Source (Cs, EI – (Ar, O2, SF6))

• Dual beam depth profiling • Effective charge compensation • Variable temperature (-130°C to +600°C)• Preparation / sample treatment chamber

XPS – Data Acquisition Unit + Software (Specs)

Principles• Pulsed primary ion beam

• Sputters off ∼ 0.1% of surface (static-SIMS)

• Secondary ions (& neutrals) emitted

• Secondary ions mass analysed by

time-of-flight

• Obtain composition, distribution &

molecular information of the surface

Time-of-Flight Secondary Ion Mass Spectrometry

Collision Cascade

Energy transferred back to surface –atoms & molecular fragments ejected

Whilst most secondary particles come off neutrally charged, a small proportion come off as either positive or negative ions

Why Time of Flight?• Parallel detection of ions - sensitivity

• 1 - 2 monolayer analysis• High mass range (up to 10 k Daltons)

• Excellent mass resolution(> 9,000)

• Effective charge compensation

Other Advantages• Elemental and chemical analysis • PPM sensitivity• High spatial resolution (100 nm) • SEM images possible (60 nm) without coating of insulators.• Depth information

- by profiling (dual beam – provides “dynamic SIMS” information)

- imaging of cross-section

Ga - main work horse, various modes• high mass resolution mode• high spatial resolution mode (200 nm), collimated mode (100 nm)• combination mode (250 nm)

Cs - enhances yield of electronegative ions• implantation reduces work function allowing 2º electrons to overcome this• use as sputter source for cleaning or profiling for negative species

O - enhances yield of electropositive ions• high electron affinity - metal more likely to give up electron• explains great increase (as much as 104) in M-O signal over M• equivalent can be accomplished by O2 bleed

Ar - neutral• use as sputter source for cleaning or profiling for positive species

SF6 - heavier fragment yields + monolayer depth resolution• higher mass + polyatomic species

Imaging from macro to micro – insulators & conductors

Ultimate Spatial Resolution

100 nm (SIMS) 60 nm (SEM)

Co-poly ferrosilanemicrobars on Si -nominally 0.5 x 3 µm2

Manner’s group - Chemistry

Cross-Section of Plant Membrane StructureCooper’s group - Forestry

Line scan showing Br penetration

Depth Information

AlH

Si 27.977

C2H428.032

CH2N

InGaAs\GaAs- Ga acquisition;

SF6 sputter

Dual Beam - interlaced mode - use of SF6 allows shallow profiling with improved

resolution

28

Mass Resolution (28 amu) >8000

Other Advantages

Molecular Information

Excellent mass resolution & sensitivity

InCs+

Compare with Cs sputter

mass / u180 200 220 240 260

mass / u300 320 340 360 380 400 420

mass / u440 460 480 500 520 540 560 580

90° 20°C O C O

Sample 1 66.6 33.4 70 30Sample 2 66.6 33.4 70 30

Sample 1 – 90° Sample 1 – 20°

Sample 2 – 90° Sample 2 – 20°

No difference in composition from survey spectra and little difference in C 1s envelope

However, ToF-SiMS shows a difference – presence of fatty acids in Sample 1

Need for Complementary Techniques

Two different paper samplesSample 1 – bad ink transfer

-1000 -900 -800 -700 -600 -500 -400 -300 -200 -100 00

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

Binding Energy (eV)

Inte

nsity

(arb

. uni

ts)

315

1A2-4GG/GEL2/72HOURS

ToF-SIMS confirms presence

Cl?

Adsorption of Antibiotic on TeethAdsorption of Antibiotic on Teeth

• Recall CHX on HA – presence confirmed by XPS

• More difficult on root canal• N & C both present in substrate• Cl signal too weak

CCa

O

N

P

Analysis Parameters:

Energy:Current:Area:

Sample Parameters:

Sample:Origin:

Polarity:

BCG1 su c6934

positiveFile: G1PR_1P.tfd PIDD: Unknow

99.6x99.6 µm²Unknow25 keV

Sputter Parameters:

PI:Energy:Current:Area:PIDD: 1.57E+017 Ions/cm²

300.0x300.0 µm²6.40 nA1 keV

Comments:

Ga+ Ar+PI:

Note: left side close to crater edge - thus ROI - rhs

TOF-SIMS IV

Depth / nm20 40 60 80 100 120 140 160 180 200 220 240

110

210

310

410

510

Inte

nsity

Substance Mass Color

Na 22.99

Al 26.98

C2H3 27.02

Si 27.98

K 38.96

Ca 39.9658Ni 57.9358NiO 73.93

Au 196.97

1 2 3 spectra extracted from these points

Can obtain depth profiles and complete mass spectra for each point

Depth scale calculated assuming literature sputter parameters

Na K 58Ni

mass / u10 20 30 40 50 60 70 80

5x10

0.2

0.4

0.6

0.8

Inte

nsi

ty

mass / u90 100 110 120 130 140 150 160

3x10

1.02.03.04.05.0

Inte

nsi

ty

Au

mass / u170 180 190 200 210 220 230 240

3x10

0.5

1.0

1.5

Inte

nsi

ty

mass / u250 260 270 280 290 300 310 320

3x10

0.20.40.60.81.01.2

Inte

nsi

ty

mass / u330 340 350 360 370 380 390 400

2x10

0.5

1.0

1.5

2.0

Inte

nsi

ty

Na

mass / u10 20 30 40 50 60 70 80

4x10

0.51.01.52.02.5

Inte

nsi

ty

mass / u90 100 110 120 130 140 150 160

3x10

0.2

0.4

0.6

0.8

Inte

nsi

ty

mass / u170 180 190 200 210 220 230 240

2x10

1.0

2.0

3.0

4.0

Inte

nsi

ty

mass / u250 260 270 280 290 300 310 320

2x10

0.51.01.52.02.5

Inte

nsi

ty

mass / u330 340 350 360 370 380 390 400

2x10

0.51.01.52.02.5

Inte

nsi

ty

mass / u10 20 30 40 50 60 70 80

4x10

0.5

1.0

1.5

Inte

nsi

ty

mass / u90 100 110 120 130 140 150 160

3x10

0.20.40.60.81.0

Inte

nsi

ty

Au

mass / u170 180 190 200 210 220 230 240

2x10

0.5

1.0

1.5

2.0

Inte

nsi

ty

mass / u250 260 270 280 290 300 310 320

1x10

2.0

4.0

6.0

Inte

nsi

ty

mass / u330 340 350 360 370 380 390 400

2x10

1.0

2.0

3.0

4.0

Inte

nsi

ty

Point 1

Point 2

Point 3

Surface Interface OntarioExpansion of Lab Facilities

• 2007• Following successful a CFI-LEF application

ToF-SIMS – ION-TOF IV• Upgraded – 2 new ion sources (February 2008)

XPS – 2 new instruments• Thermo Scientific K-Alpha (August 2007)• Thermo Scientific Theta (March 2008)

Other Equipment• Surface Profilometer - KLA Tencor P16+ (August 2007)• Target Sectioning System – Leica EM TXP (December 2007)• Cryo-Ultramicrotome – Leica EM UC6/FC6 (~ May 2008)• Vacuum/Cryo “Suitcase” – Thermionics (~ June 2008)• Preparation/Reaction Chambers – Old MAX (ongoing)

ION-TOF ToF-SIMS IV

• Multiple Ion Sources• Liquid metal ion gun (Bin) - rapid submicron imaging, cluster source (to Bi7) - enhances fragmentation and yield

• Third ion gun column - C60 source - enhances fragmentation and yield, shallow & molecular

depth profiling

• Dual Beam Depth Profiling • Cs / EI / C60 for sputtering, Bi, Cs or EI for spectral acquisition

• Variable Temperature• Temperature stage (-150°C to +600°C)

• Pulsed secondary electron detector• (SEM on insulators)

• Updated software control

Use of heavier & polyatomic fragments - Aum

New development (2002) (superseded by Bim (Sept. 2004))

Different clusters (Au, Au2, Au3) selectable.

Unlike SF6, keeps the imaging capabilities of a LMIG

No features discernable with Ga

More on this from Albert Schnieders

~ 19x enhancement with Au3+ over Au1

+

Note this type of work is totally impossible with Ga gun

Cholesterol

PhospholipidsDiglycerides

Au3+ - mouse brain slice - no treatment

195 360 390

450 550 680 900

Tissue Molecular Ion Imaging with Au Clusters

Touboul et al. Analytical Chemistry 76 (2004) 1550

Peter Sjövall will probably have more examples

Use of heavier & polyatomic fragments – C60

• Enhances fragmentation and yield

• Shallow depth profiling

Tt=29 ps

•Molecular depth profiling possibilities on some systems

Larger volume is altered for Ga15x more material removed with C60

t = 29 ps15 keV Ga 15 keV C60

Barbara Garrison’s Group – Penn State: Anal. Chem., 75, 4402-4407 (2003)

• Automated, compact XPS• Monochromated Al Kα X-ray source• Variable spot - 30 - 400 µm• Effective charge compensation• Ar+ ion gun for depth profiling, Zalar rotation possible

• 128 channel detector - rapid spectral acquisition

• Large area sample platen for mounting sample(s)

• Ease of selection of analysis area• Wedges (20° & 30°) allow ARXPS to be performed

• All aspects digitally controllable and capable of automation, including data work-up and report generation

• High volume, rapid throughputS-15S-14S-13

S-12S-11S-10

S-9S-8S-7

S-6S-5S-4

S-3S-2S-1

Thermo Scientific K-Alpha

0.00E+00

1.00E+05

2.00E+05

3.00E+05

4.00E+05

020040060080010001200

Cou

nts

/ s

Binding Energy (eV)

Survey1 Scan, 1 m 8.1 s, 400µm, CAE 200.0, 1.00 eV

C1s

F1s

N1s

O1s

Si2p

3.0940255.502.53102.220.817Si2p

17.94669633.373.02532.352.930O1s

1.9448203.722.95399.941.800N1s

1.3266877.692.21689.334.430F1s

75.701107556.572.66285.031.000C1s

At. % Area (P) CPS.eVFWHM eVPeak BESF Name

PHEMA : 4.7kDA HA(5g/L)

Experiment\X-Ray000 400um - FG ON\S-6

0.00E+00

2.00E+03

4.00E+03

6.00E+03

8.00E+03

1.00E+04

1.20E+04

1.40E+04

1.60E+04

1.80E+04

2.00E+04

280282284286288290292294296298

Cou

nts

/ s

Binding Energy (eV)

C1s Scan #210 Scans, 400µm, CAE 20.0, 0.10 eV

C1s

C1s A

C1s BC1s C

C1s D

C1s F

2.921008.931.02289.531.000C1s F

18.456383.931.12285.671.000C1s D

4.321494.351.14287.711.000C1s C

4.001381.321.08288.891.000C1s B

12.474314.781.10286.701.000C1s A

57.8420021.521.19285.031.000C1s

At. % Area (P) CPS.eVFWHM eVPeak BESF Name

Survey and high resolution XPS on polymer sample

• High-end, small-spot XPS• Monochromated Al Kα X-ray source• Variable spot - 15 - 400 µm• Dual anode (Mg/Ag) nonmonochromated X-ray source

• Effective charge compensation• Ar+ ion gun for depth profiling, Zalar rotation possible

• Parallel ARXPS (60° range)• 2-d multi-channel detector

110 channels for energy, 96 channels for angle

• Large area sample platen• Special mount for heating/cooling

(-150°C to +600°C)

• Field emission gun for Auger/SEM (95 nm resolution)

• Multi-port preparation chamber with heating/cooling, sample parking and port for vacuum/cryo “suitcase”

Thermo Scientific Theta Probe

(See poster by Joyce Koo)

Examples

ARXPS – ATRP on Si (Krull’s group – UTM)

Contamination on Au wire – coating thickness

Snapshot Imaging – Spectrum Mapping

NiCr Alloy

(Coyle’s Group

U. Of T.)

Depth Profiling GaAs multi-stack layer

3 keV Ar+, 3 µA, 3 x 3 mm2 - rotated

Ruda’s Group – U. of T.

ToF-SIMS Dynamic SIMS Auger XPS

ElementalSensitivity XXXX XXXXX XX XX

BondingInformation XXX X XX XXXXX

MolecularInformation XXXXX - - -

SpatialResolution XXXX XXXX XXXXX XX

Depth ProfilingSpeed XXXX XXXXX XXX XX

Primary Organics Inorganics Inorganics OrganicsApplication & Inorganics & Inorganics

The following table summarises some of this information for the most common techniques

Other EquipmentKLA-Tencor P16+ Surface Profilometer• 2-d line profiles• 3-d mapping• Low force option• Extended (1 mm) range (z)• Long scan (200 mm) length (x)• 20 site sequencing (line/map) capability

Leica EM UC6/FC6 Cryo-Ultramicrotome• Sectioning of biological and other samples at temperatures from -15° to -185°C

• Virtual connection to ToF-SIMS, XPS and preparation chambers via side port for vacuum/cryo “suitcase”

Leica EM TXP Target Sectioning System• Stereo microscope to easily view target area• Ease of use. Sawing, milling, grinding and polishing exactly to target - no need to remove sample

Vacuum/Cryo “Suitcase”• Virtual connection of preparation chambers, ToF-SIMS, Thetaprobe XPS and cryo-ultra microtome

Preparation/Reaction Chambers

• SI-Ontario allows scientists and engineers ready access to modern surface analytical equipment andthe related expertise

• Leading edge equipment in major areas of surface analysis

• Over the years this core-resource has served both academia and industry – truly

“creating partnerships for innovative research”

Acknowledgements

Surface Interface Ontario was made possible through funding provided by: Canadian Foundation for Innovation, Ontario Research Fund (formerly Ontario Innovations Trust), University of Toronto, McMaster University, Environment Canada, Celestica, VALE INCO, Novelis, Amtel and ITL.

Further support was received from several departments, both at Toronto and McMaster, via faculty participation.

This Workshop was made possible with donations from OCE, SFR, Datacomp, Ion-TOF USA, Thermo Scientific, Leica & KLA-Tencor