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Applications of XPS, AES, and TOF-SIMS
Scott R. Bryan
Physical Electronics
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Materials Characterization Techniques
2
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
3
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
4
Depth of Analysis
Courtesy of EAG Laboratories
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Auger Electron Spectroscopy (AES)
5
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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
77
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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
9
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
10
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
11
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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
12
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X-ray Photoelectron Spectroscopy (XPS)
13
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What is XPS used for?
14
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
15
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Argon Gas Cluster Beam (GCIB) cleaning of Polyimide
16
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
20
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)
20
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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
25
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
26
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.
27
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O2+ Ion Gun Sputter Depth Profiling
28
▬ 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
29