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Applications of XPS, AES, and TOF-SIMS

Scott R. Bryan

Physical Electronics

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Materials Characterization Techniques

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Microscopy

• Optical Microscope

• SEM

• TEM

• STM

• SPM

• AFM

Spectroscopy

• Energy Dispersive X-ray Spectroscopy (EDX)

• X-ray Diffraction (XRD)

• Electron Energy Loss Spectroscopy (EELS)

• Auger Electron Sepctroscopy(AES)

• X-ray Photoelectron Spectroscopy (XPS)

• Secondary Ion Mass Spectrometry (SIMS)

• Fourier Transform Infrared Spectroscopy(FTIR)

• Raman Spectroscopy

• Photoluminescence (PL)

• Dynamic Light Scattering (DLS)

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Materials Characterization Techniques

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Microscopy

• Optical Microscope

• SEM

• TEM

• STM

• SPM

• AFM

Spectroscopy

• Energy Dispersive X-ray Spectroscopy (EDX)

• X-ray Diffraction (XRD)

• Electron Energy Loss Spectroscopy (EELS)

Auger Electron Sepctroscopy(AES)

X-ray Photoelectron Spectroscopy (XPS)

• Dynamic Secondary Ion Mass Spectrometry (D-SIMS)

Time-of-Flight Secondary SIMS (TOF-SIMS)

• Fourier Transform Infrared Spectroscopy(FTIR)

• Raman Spectroscopy

• Photoluminescence (PL)

• Dynamic Light Scattering (DLS)

Used for surface, thin film, and interface analysis

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Surface Chemical Analysis Techniques

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Depth of Analysis

Courtesy of EAG Laboratories

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Auger Electron Spectroscopy (AES)

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What Information Does Auger Provide ?

Surface composition at high spatial resolution

– Secondary Electron Imaging (3 nm)

– Elemental analysis (spectra) (8 nm)

– Elemental imaging (mapping)

– High energy resolution spectra, imaging and depth profiling

Sputter depth profiling

– Reveals thin film and interfacial composition

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SE

F

Semiconductor Defect Identification with Auger

Green=C Red=Al Blue=Si

500 1000 1500 2000Kinetic Energy (eV)

"Petal"

Off "Petal"

C OF

Si

Si

Si

Si

C

O

Auger detects

C & F on thin petal

EDX does NOT detect

C & F on 10-15 Å thin petal

Petal

Off Petal

5kV

5kV

200 600 1000 1400 1800Kinetic Energy (eV)

SiAl

FO

N

C

S

Particle

Auger detects Al particle

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Auger KLL spectrum of native oxide on Al foil measured on PHI CMA at 0.5% (blue) and 0.1% (red) energy

resolution, after background subtraction.

1350 1360 1370 1380 1390 1400 1410 1420-50

0

50

100

150

200

250

300

350

1393.4 eV (Al metal)

1386.9 eV (Al oxide)

Kinetic Energy (eV)

N(E

) cps

0.5%

0.1%

Al KLL Spectra of Native Oxide on Al Foil

Auger Chemical State Analysis

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Auger Chemical State AnalysisHigh Energy Resolution Imaging of Semiconductor Chemical States

A B

C

Composite Si KLLIC412_256.map: Pad 41 PHI

2012 Sep 22 10.0 kV 10 nA FRR 0.00 s

Si4/-1 RSF

3462175

113732920 µm

20

µm

Si4

Elemental Si

SilicideSi Oxynitride

Si KLL image with ROI areas

Si KLL Basis Spectra

1604 1608 1612 1616 1620 1624

Kinetic Energy (eV)

Inte

nsity

1605 1615 1625Kinetic Energy (eV)

Inte

nsity

0.1 % high energy

resolution spectral

windowed mapping

LLS fitting from the basis

spectra extracted from

regions of interest

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Silicide

Si M

eta

l

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Auger Chemical State AnalysisHigh Energy and Spatial Resolution Imaging of Semiconductor Chemical States

IC412_256.map: Pad 41 PHI

2012 Sep 22 10.0 kV 10 nA FRR 0.00 s

Si4/-1 RSF

32297

746520 µm

20

µm

Si4.ls3

IC412_256.map: Pad 41 PHI

2012 Sep 22 10.0 kV 10 nA FRR 0.00 s

Si4/-1 RSF

47.0

0.020 µm

20 µ

m

Si4.ls1+Si4.ls2+Si4.ls3

200 µm FOV SEI of a semiconductor bond pad

0.1% energy resolution data

A B

ED

SEI

Elemental Si Si Oxynitride

SilicideC4094

892.8

IC.401.sem: Pad 41 PHI

2012 Sep 21 10.0 kV 10 nA FRR

SEM/-1 RSF

20 µm

20

µm

SEM

IC412_256.map: Pad 41 PHI

2012 Sep 22 10.0 kV 10 nA FRR 0.00 s

Si4/-1 RSF

3462175

113732920 µm

20

µm

Si4

Si KLL Peak Area

IC412_256.map: Pad 41 PHI

2012 Sep 22 10.0 kV 10 nA FRR 0.00 s

Si4/-1 RSF

32297

746520 µm

20

µm

Si4.ls1

IC412_256.map: Pad 41 PHI

2012 Sep 22 10.0 kV 10 nA FRR 0.00 s

Si4/-1 RSF

32297

746520 µm

20

µm

Si4.ls2

F Si Chemical States

Auger Color Overlay 20kV 10nA 256x256 pixels

Green: Elemental Si Blue: Si Oxynitride Red: Silicide

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Silicide (red)

Oxynitride (blue)

Elemental Si (green)

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PHI 710: Nanoscale Depth Profiling

FOV: 2.0 µm

F

0.5 µm

1

P from the growth gas is detected

on the surface of a Si nanowire

60 nm Diameter Si Nanowire

20 kV, 10 nA, 12 nm Beam

100 300 500 700Kinetic Energy (eV)

Inte

nsity

O

CSi

P

Surface Spectrum of NanowireSEI

Atom %

Si 97.5

P 2.5

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PHI 710: Nanoscale Depth Profiling

500 V Ar sputter depth

profiling shows a non-

homogeneous radial P

distribution

The data suggests Vapor-

Solid incorporation of P

rather than Vapor-Liquid-

Solid P incorporation0

0.5

1

1.5

2

2.5

3

0 2 4 6

Ph

osp

ho

rou

s (

ato

m %

)

Sputter Depth (nm)

Depth Profile of the Si Nanowire

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X-ray Photoelectron Spectroscopy (XPS)

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What is XPS used for?

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Metal

Plastic

Paint

Glass

Ceramic

Fabric

Semiconductors

Biomaterials

Composites

We have analyzed:

Mirrors, lenses, windshields, integrated circuits, circuit

boards, fruit flies, teeth, heart valves, pacemakers, stents,

relay contacts, make-up, shampoo residue on hair, moon

rocks, space shuttle tiles, mold, hip joints, dental floss,

dirty socks, solid rocket fuel, gaskets, brake pads, lipstick,

adhesive labels, paper, ink, Mr. Potato Head, etc….

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XPS: Quantitative Elemental & Chemical Information

02004006008001000Binding Energy (eV)

c/s

-O K

LL

-O1

s

-C1s

-O2

s

280285290295300Binding Energy (eV)

c/s

C 1s

CHC-OO=C-O

Atom %

C 70.9

O 29.1

% of C 1s

CH 62.7

C-O 20.2

O=C-O 17.1

XPS survey spectra provide

quantitative elemental information

High resolution XPS spectra provide

quantitative chemical state information

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Argon Gas Cluster Beam (GCIB) cleaning of Polyimide

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2782802822842862882902922942962980

200

400

600

800

1000

1200

1400

1600

1800

Binding Energy (eV)

c/s

C-C

37.9 (at.%) of C 1s

C-N

C-O

N-C=O

pp*⇒

2782802822842862882902922942962980

200

400

600

800

1000

1200

1400

1600

1800

c/s

C-C （including contaminants）

45.0 (at.%) of C 1s

C-N

C-O

N-C=O

pp*

As received – CHx contaminated After GCIB cleaning

Binding Energy (eV)

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Argon Gas Cluster Ion Beam (GCIB) cleaning of TiO2

4504554604654704750

0.5

1

1.5

2

2.5

3

3.5

4x 10

4

Binding Energy (eV)

c/s

5255305355400

0.5

1

1.5

2

2.5

3

3.5

4

4.5x 10

4

Binding Energy (eV)

c/s

2802852902950

1000

2000

3000

4000

5000

6000

Binding Energy (eV)

c/s

Ti 2p O 1s C 1s

As received

After cleaning

As received

After cleaning

After cleaning

As received

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XPS Depth Profile of Thin Films

Sputter depth profile of an

architectural glass coating

0 50 100 150 200

10

20

30

40

50

60

70

Sputter Depth (nm)

Ato

mic

Concentr

ation (

%)

Aluminum

Nitrogen

Niobium

Titanium

Oxygen

Silicon Silicon

Oxygen

Nitrogen

Titanium

Sputter Depth Profile

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GCIB Depth Profile of Organic LED Layers

Sample courtesy of Prof. Russell Holmes, U of MN3954004054100

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40

60

80

Binding Energy (eV)

N1s (BPhen)N1s (TCTA)

0 50 100 1500

20

40

60

80

100

Sputter Depth (nm)

Ato

mic

Concentr

ation (

%)

C 1s

Si 2pO 1s

10 kV Ar2500+ Sputtering

N 1s (BPhen)

10X

N 1s (TCTA)

10X

Si

100%

0%100 nm

Native Oxide

Sputter Depth Profile of a Graded OLED Test Structure

BPhen

TCTA

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Time-of-Flight

Secondary Ion Mass Spectrometry

(TOF-SIMS)

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Surface Chemical Analysis Techniques

21Courtesy of EAG Laboratories

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What is TOF-SIMS used for?

Surface Mass Spectra with MS/MS:

– Identification of all atomic and molecular species on surface

– High sensitivity and molecular specificity

Imaging

– 2D elemental and molecular distributions

Depth Profiling

– Elemental and molecular depth distributions

FIB-TOF

– Accurate 3D distributions of heterogeneous materials

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Schematic of the PHI nanoTOF II

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PHI nanoTOF II with MS/MS

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TOF-SIMS of a Commercial Polypropylene

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0 100 200 300 400

212134

2969

9123

39 58

481

284

304

256312

Co

un

ts

500

368

×20

C7H7

C3H8NNa

K

C9H12N

0

2.0E+5

4.0E+5

6.0E+5

8.0E+5

1.0E+6

1.2E+6

MS1 Spectrum of Polypropylene surface

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Unambiguous Identification of m/z 304

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polymer additive Benzalkonium, m/z 304

304-MS2 Pos BenzyldodecyldimethylammoniumHead to Tail MF=692 RMF=971

50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300

0

4

8

4

8

43.000

57.9

58.000

71.000 86.000

91.000

91.0

97.000 114.000 134.000

136.2

147.000 160.000 173.000

178.0

186.000 199.000

212.000

212.3

218.000 231.000

241.9

244.000 257.000 270.000

271.9

283.000

304.000

304.3

TOF-SIMS MS/MS Spectrum of Unknown

NIST Library MS/MS Spectrum

ESI with QQQ

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Total Area Spectrum

Primary Ion Beam

Total Ion Image

m/z

m/z

Chemical Map 2

Chemical Map 1

m/z

Region 2 Spectrum

Region 1 Spectrum

Sample

TOF-SIMS Imaging

Spectra from selected areas of the total ion image or images from selected peaks of

the total area spectrum can also be obtained for complete analysis after data acquisition.

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O2+ Ion Gun Sputter Depth Profiling

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▬ D-SIMS

▬ TOF-SIMS

Excellent Comparison between TOF-SIMS vs D-SIMS Layer (Depth Resolution)

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Conclusions

Auger Electron Spectroscopy (AES)

» Use for highest spatial resolution surface analysis

X-ray Photoelectron Sepctroscopy (XPS)

» Use for quantification of elements and oxidation states

Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

» Use for identification of organic compounds

» Use for trace level surface analysis

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