1. LaB6 Scanning Electron Source
Angle Dependent XPS
Electrons
X-rays
Ellipsoidal
Monochromator
Photoelectrons
SCA
LaB6 Scanning Electron Source
Multi Channel
Detector
Scanning Input Lens
Al Anode
5-Axis Sample Stage
The analysis depth is varied by changing the sample tilt angle

2. Angle Dependent XPS q = 90° q = 10° d = l sin q q d d Analyzer
Input Lens
Analyzer
Input Lens
X-ray Beam
X-ray Beam
e -
e - q
q = 90°
q = 10° q d d
d = analysis depth
l = electron mean free path
q = photoelectron take off angle
d = l sin q

3. ADXPS Profile of the Native Oxide on a Si Wafer Surface
Chemical Composition Atomic Concentration Profile
280
285
290
295 2 4 6
500
1000
1500
Binding Energy (eV)
c/s
C 1s
525
530
535
540 5 10 15
O 1s
x103 95
100
105
110
Si 2p
metal
oxide
Corrected for Take-Off-Angle intensity variation 55 50
O 1s 45 40 35
Si 2p - metal
Atomic Concentration (%) 30 25 20
Si 2p - oxide 15
C 1s 10 5
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1
Sine of the Photoelectron Take-off Angle

4. ADXPS Profile of the Native Oxide on a Si Wafer Surface
Chemical Composition Atomic Concentration Profile
Curve Fitting Used to Isolate Si Metal and Oxide
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1 5 10 15 20 25 30 35 40 45 50 55
sine [toa]
Atomic Concentration (%)
O 1s
C 1s
Si 2p - metal
Si 2p - oxide 92 94 96 98
100
102
104
106
108
110
112
500
1000
1500
2000
2500
3000
3500
4000
Binding Energy (eV)
c/s
Pos. Chem. State
Si 2p3 metal
Si 2p1 metal
Si 2p oxide
Si 2p

5. Interpretation of ADXPS Profiles Using a Stratification Algorithm
The stratification algorithm requires peak intensity data from two or more take off angles. The minimum data set should include a high and low take off angle.
Estimation of layer order
The peak intensity ratios of all peaks are compared between all the measured take off angles. The number of layers and layer order is based on the correlation of peak intensity ratios.
Estimation of film thickness and composition
The peak intensities measured at the high take off angle and the layer order information are used to calculate layer thickness and composition.
The algorithm is useful for qualitative sample to sample comparisons

6. Assumptions and Limitations of the Stratification Algorithm
Stratification model assumptions
Individual layers are continuous and uniform in thickness
Individual layers are uniform in composition
Interfaces are abrupt
Stratification model limitations
Generic electron mean free paths are applied for thickness calculations
Since the model is not calibrated for the sample being measured, the absolute layer thicknesses may contain systematic error
If the actual sample composition violates any of the assumptions, this will impact the layer detection process, composition, and thickness results

7. Stratification Algorithm Interpretation of the ADXPS Profile of the Native Oxide on a Si Wafer
Chemical Composition Atomic Concentration Profile
Structure Analysis with automatic layer assignment
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1 5 10 15 20 25 30 35 40 45 50 55
sine [toa]
Atomic Concentration (%)
O 1s
C 1s
Si 2p - metal
Si 2p - oxide
Structure
Description
-2.5 -2
-1.5 -1
-0.5
Depth (nm)
C 1s (100.0 %)
O 1s (67.0 %)
Si 2p – oxide (33.0 %)
Si2p – metal (100.0 %)
Layer1
Layer2(2.03 nm)
Residue (1.77e-008)
Top Layer(0.19 nm)

8. ADXPS Profile of a Self Assembled Thiol Monolayer on Au
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1 10 20 30 40 50 60
sine [toa]
Atomic Concentration (%)
S 2p
O1s
Au 4f
C 1s (C-C/C-H)
C 1s (C-O)
Chemical Composition Atomic Concentration Profile 80 85 90 95 5
0.5 1
1.5 2
x 10
Binding Energy (eV)
c/s
Au4f
525
530
535
540
2000
4000
6000
O1s
280
285
290
295
5000
10000
C1s
155
160
165
170
500
1000
1500
S2p
Sample in courtesy of Dr. Sophie Noel
Laboratoire de Génie Electrique de Paris
URA CNRS Universités Paris

9. ADXPS Profile of a Self Assembled Thiol Monolayer on Au
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1 10 20 30 40 50 60
sine [toa]
Atomic Concentration (%)
S 2p
O1s
Au 4f
C 1s (C-C/C-H)
C 1s (C-O)
Chemical Composition Atomic Concentration Profile
Peak Fit Routine Separating C 1s Chemical States
278
280
282
284
286
288
290
292
294
296
298 1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
x 10 4
Binding Energy (eV)
c/s
Pos. Sep. %Area
C-C/C-H
C-O
C 1s

10. ADXPS Profile of a Self Assembled Thiol Monolayer on Au
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9 1 10 20 30 40 50 60
sine [toa]
Atomic Concentration (%)
S 2p
O1s
Au 4f
C 1s (C-C/C-H)
C 1s (C-O)
Chemical Composition Atomic Concentration Profile
Structure Analysis with automatic layer assignment
Structure
Description
-2.5 -2
-1.5 -1
-0.5
Depth (nm)
O 1s (41.3 %)
C 1s C-O (58.7 %)
C 1s C-C/C-H (100.0 %)
S 2p (100.0 %)
Au 4f (100.0 %)
Layer1
Layer2(0.11 nm)
Layer3(1.58 nm)
Top Layer(0.31 nm)
Residue (1.18e-010)

11. HfO2 on Si ADXPS Profile Hf 4f 100 4 80 x 10 O 1s 2.5 60 2
Atomic Concentration (%)
1.5 40
c/s
Hf 4f 1
75° 20
45°
Si 2p (oxide)
0.5
Si 2p (metal)
30°
C 1s
20°
0.4
0.5
0.6
0.7
0.8
0.9 1 30 26 22 18 14
sine [toa]
Binding Energy (eV)

12. HfO2 on Si Structure Analysis 1.11 nm O 1s 71.2% Hf 4f 28.8%
-0.5
1.11 nm O 1s 71.2% Hf 4f 28.8% -1
-1.5 -2
Depth (nm)
-2.5
2.96 nm O 1s 65.2% Si 2p 13.8% Hf 4f 21.0% -3
-3.5 -4
Si 2p 100%
-4.5 1 2
This model was created by a stratification analysis tool in MultiPak. Generic attenuation lengths were used.