Thin films seen in the light of high energy synchrotron radiation: stress and microstructure analysis using energy-dispersive diffraction.

Thin films seen in the light of high energy synchro-tron
radiation: Stress and microstructure analysis
using energy-dispersive diffraction Dept. of Microstructure and
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
Residual Stress Analysis
XIII Brazilian MRS meeting, João Pessoa, Brazil,
September 28 – October 02, 2014
Ch. Genzel

Outline
 Introduction BESSY II
 Angle- vs. energy-dispersive
diffraction
 Basic principles of X-ray stress
analysis (XSA)
 Examples
 XSA on coated cutting tools
 Stress and composition gradients
 In-situ study of thin film processing
 What about the microstructure?
 Summary
2

3
The Mission of the Helmholtz-Zentrum Berlin
Wannsee
BER II Reactor
Adlershof
BESSY II
Two large scale facilities for
investigating the structure
and function of matter
Energy research
Neutrons Synchrotron

4
Department of microstructure and residual stress analysis
Synchrotron
ASAXS
Diffraction:
Stress, texture,
microstructure
Scattering:
Nanostructure
Imaging:
Neutrons
E3
Synchrotron
EDDI
Time resolution
Depth resolution
Spatial resolution
X-ray
ETA

Thin films and coatings in every day use
CIS
Thin films and coatings fulfill
various important functions in
our daily life …
5

Designing of property-enhanced coating systems
Al2O3
Composition &
Microstructure Texture
TiCN
Residual stress
Coating properties can
be tailored in the
manufacturing process.
6

The role of diffraction methods ...
7

Information provided by X-ray diffraction
X-Ray Diffraction: Crystal structure
Nondestructive
Phase-selective
Information depth nm ... cm
before sulphurization
after
Energy [keV]
Intensity [a. u.]
Line position and shift:
 Crystal structure
 Residual stresses
Line width and shape:
 Domain/particle size
 Microstrain, lattice defects
Line intensity:
 crystallographic texture
 Reaction kinetics
Fluorescence lines:
 Element distribution
8

sload
1000 ºC
T
RT
0 t 5 min ... with high spatial
9
Challenges in structural research with diffraction methods
Investigations
should be done ...
... in situ (time
resolution)
resolution
z
y x
... under service conditions
Thin films: Superposition of gradients
of residual stress, texture and
composition on very limited space!

Well-known and mainly used: Angle-dispersive X-ray diffraction
 0D: Scintillation counter
 1D: Position sensitive det.
 2D: Channel plate
2q
Photon
source
monochromatic
X-ray beam
coating
E1 = E2 = E3 …
CoKa  surface sensitive (low energies)
30 40 50 60 70 80 90
2q [deg]
15
10
5
0
I [cps]
 high angular resolution
 long counting times (scintillation
counter)
 complex experimental setup
variable!
substrate
10

Features of energy-dispersive X-ray diffraction
fixed!
white beam
coating
substrate
E1 < E2 < E3 …
 Fixed experimental setup
 Complete diffraction patterns
in fixed directions (unique!)
 Different diffraction lines Ehkl
originate from different depths
11

12
Strategy for coating stress analysis
Materials Science Beamline EDDI
ETA diffractometer
Angle-dispersive diffraction (lab)
 Low energies (5 … 17 keV)
 Surface sensitive
coating
substrate
Energy-dispersive diffraction
(synchrotron)
 Energies up to 120 keV
 Sensitive in deeper zones

The EDDI beamline for Energy Dispersive DIffraction
EDDI@BESSY II:
 E  (8 … 120) keV
 2.4·1011 ph·s-1/0.1% bw
Experimental hutch
PVD chamber Two detector setup
DHS 1100 heating station Mechanical load device
High resolution setup
13

Basic principles of X-ray stress analysis
14

Principle of residual stress analysis by diffraction methods
angle-/energy-dispersive
1. Measurement of the diffraction line
shift for various orientations (j,y)
15
2. Evaluation of the lattice strain
3. Evaluation of the residual stress
tensor via Hooke‘s law.

The sin2y-method
m < 0: compressive stress
0 1
 In-plane homogeneous film with
biaxial residual stress state:
 Fundamental equation of X-ray
stress analysis takes the form:
m > 0: tensile
stress
Residual stress s(z) require a more sophisticated treatment ...
16

XSA on coated cutting tools
17

„Thin“system (D = 5 μm) „Thick“system (D = 18 μm)
Al2O3
TiCN
0.176
0.174
0.0877
0.0875
as-grown
blasted
as-grown
blasted
18
XSA on multilayer systems: Influence of the coating design
WC 5μm
Al2O3
TiCN
WC
10μm
TiCN
0.2 0.4 0.6 0.8 1
0.0873
0
d422 [nm]
sin²y
as-grown
as-grown
0.2 0.4 0.6 0.8 1
0.1745
0.1735
0.1725
0.08760
0.08755
0.08750
0
d422 [nm]
sin²y
blasted
CuKa
Al2O3
0.2 0.4 0.6 0.8 1
0.172
0
d024 [nm]
sin²y
0.2 0.4 0.6 0.8 1
0.1715
0
d024 [nm]
sin²y
blasted
CuKa
steep
stress
gradient!

ED-XSA in the interfacial substrate zone
Al2O3
TiCN
0
- 0.5
-1.0
001
101
110
002
as-grown
blasted
2q = 9°
30 40 50 60
1000
800
600
400
200
E [keV]
I [cts]
100-WC
001-WC
101-WC
110-WC
002-WC
111-WC
coating reflections
5μm
WC
E1 < E2 < E3
M. Klaus et al., Thin solid films 517 (2008), 1172.
1 2 3 4 5 6 7
-1.5
001
111
0
s|| [GPa]
 [μm]
coating
19
 Application of the sin2y-method
to each line Ehkl
 Assignment of the obtained
stress values <shkl> to average
information depth <hkl>

Interlayer gradient: Balance between coating and substrate
TiCN
Al2O3
WC 5μm
1 2 3 4 5
Intralayer gradient: Balance within the Al2O3 top layer
TiCN
Al O 3
BL
2
as-grown
blasted
4 8 12 16 20
z [μm]
2
0
- 2
- 4
- 8
2
0
- 2
- 4
- 6
- 8
TiN
0
s|| [GPa]
Al2O3
TiCN
WC
10μm
z [μm]
- 6
0
s|| [GPa]
TiCN
TiN
Al O
BL
as-grown
blasted
2 3
001
101
110
002
as-grown
blasted
1 2 3 4 5 6 7
0
- 0.5
-1.0
-1.5
001
111
0
s|| [GPa]
 [μm]
001
101
110
002
blasted
1 2 3 5 6 7
0
-0.5
-1.0
-1.5
111
0 4
s|| [MPa]
 [μm]
unblasted
Residual stress balance in multilayer systems
20

Separation of residual stress and
composition gradients
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014 21

111
Exp. austenite
Residual stress (-N) Composition (-N)
22
Residual stress analysis in expanded austenite layers
2q = 8°
111-N
200-N 200
Substrate
S. Jegou et al. Thin solid films 530 (2013), 71.
 Strain depth profiling
in the scattering vec-tor
mode.
 Application of the
sin²y method for
predefined depths .
m  = 5 μm
sin2y*
d0

Energy-dispersive diffraction:
In-situ study of thin film processing
23

metallic precursor
Sulfur
24
Rapid thermal processing (RTP) of CuInS2 thin films
 Sulphurization of Cu/In precursor
on Mo/glass substrate
 Sulphurization chamber mounted
on the diffractometer.
 Fast recording of ED spectra
Indium
Copper
Molybdenium
Glass
CuInS2
DE

The two-detector setup @ EDDI
Simultaneous acquisition of
diffraction patterns in fixed
but arbitrary measuring
directions!
High resolution In-situ
sin²y
dy
25

In-situ analysis of thermal stresses in thin Mo films on glass
aMo = 510-6 K-1 / aGlass = 9.510-6 K-1
Ch. Genzel et al., J. Strain Analysis 46 (2011), 615
sin2y-based stress analysis
Ds
26

What can we learn about
the microstructure?
27

In-situ microstructure analysis: recrystallization of CuInS2
Substrate temperature [ºC]
50 150 250 350 450
Recrystal-lization
112- CuInS2
10 50 100 150
Process time [min]
Energy [keV]
30
Recrystallized CuInS2
112- CuInS2
Lorentzian,
broad
Gaussian,
small
29 30 31 32 33
Energy [keV]
Energy-dispersive
diffraction line
profile analysis?
H. Rodriguez-Alvarez, PhD thesis, TU Berlin, 2010.
Small-grained,
defective CuInS2
Driving Forces?
Enhancement?
Normalized Intensity [a. u.]
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014 28

Instrumental resolution in ED diffraction (EDDI beamline)
LaB6 SRM660b Energy-dispersive RIETVELD
Instrumental resolution:
(G  Full width at half maximum)
refinement:
D. Apel et al., Z. Kristallogr. 226 (2011), 943.
29

Multiple vs. single line analysis
2q = 10°
CeOED Rietveld study of size-related
2 XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014
broadening in ceria powder:
 EDDI: DV = 226(31) Å+)
 Size-Strain RR: DV = 221…236 Å++)
+) D. Apel et al., Z. Kristallogr. 226 (2011), 943.
++) D. Balzar et al., JAC 37 (2004), 911.
112- CuInS2
29 30 31 32 33
Energy [keV]
Normalized Intensity [a. u.]
Energy [keV]
Intensity [counts x 103]
Needs single line
analysis!
30

Single line analysis of domain size and microstrain
 Line profiles described by pseudo-Voigt
(pV) functions:
pV(E) = x·Cauchy(E) + (1-x)·Gaussian(E)
(0  x  1)
 Domain size  Cauchy width bC
 Micro strain  Gaussian width bG
Broadening angle dispersive energy dispersive
Size
Strain
Size and strain broa-dening
depend on q!
Only strain broade-ning
D. Thomas, PhD thesis, TU Berlin, 2012.
depends on E!
domain size [nm]
interrupt temperature [°C]
micro strain [%]
initial
state
31

Summary
 Energy-dispersive synchrotron X-ray diffraction:
Versatile tool for many fields of materials sciences.
 Under fixed diffraction conditions complete diffrac-tion
patterns are recorded.
 Thin film analysis and (high energy) ED diffraction fit
together! The methods allows for:
o (Residual) stress analysis, even in complex cases (multi-layers,
separation of stress and composition gradients ...)
o Fast in-situ study of thin film growth processes
o Microstructural characterization (ED line profile analysis)
o ...
32

My special thanks go to:
Manuela Klaus
Ingwer A. Denks
Rodrigo Coelho
Daniel Apel
Diana Thomas
Matthias Meixner
Tillman Fuss
Guido Wagener
Roland Mainz
Humberto Rodriguez-Alvarez
Davor Balzar
33

Thank you very much
for your attention!
34

Thin films seen in the light of high energy synchrotron radiation: stress and microstructure analysis using energy-dispersive diffraction.

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