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$: Thin films seen in the light of high energy synchrotron radiation: stress and microstructure analysis using energy-dispersive diffraction.$
XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014


Thin films seen in the light of high energy synchro-tron radiation: Stress and microstructure analysis using energy-dispersive diffraction Dept. of Microstructure and

Residual Stress Analysis

Ch. Genzel


Outline

BESSY II Introduction 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


The Mission of the Helmholtz-Zentrum Berlin

WannseeBER II Reactor

AdlershofBESSY II

Two large scale facilities for investigating the structure and function of matterEnergy research

SynchrotronNeutrons


Department of microstructure and residual stress analysis

Synchrotron

ASAXS

Diffraction:Stress, texture, microstructure

Scattering:Nanostructure

Imaging:

E3

Neutrons

Synchrotron

EDDI

Time resolution

Depth resolution

Spatial resolution

X-ray

ETA


Thin films and coatings in every day use

CISCIS

Thin films and coatings fulfill various important functions in our daily life …

5


Designing of property-enhanced coating systems

Composition &Microstructure Texture

Residual stress

Al2O3

TiCN

Coating properties can be tailored in the manufacturing process.

6


The role of diffraction methods ...

7


Information provided by X-ray diffraction

Energy [keV]

Inte

nsity

[a. u

.]

afterbefore sulphurization

X-Ray Diffraction: Crystal structureNondestructivePhase-selectiveInformation depth nm ... cm

Line width and shape: Domain/particle size Microstrain, lattice defects

Line intensity: crystallographic texture Reaction kinetics

Fluorescence lines: Element distribution

Line position and shift: Crystal structure Residual stresses

8


Challenges in structural research with diffraction methods

9

Investigations should be done ...

... in situ (time resolution)

0 5 mint ... with high spatial resolution

zxy

... under service conditions

sload

RT

1000 ºC

T

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

2q [deg]

30 40 50 60 70 80 90

0

5

10

15

I [cp

s]

CoKa surface sensitive (low energies) high angular resolution long counting times (scintillation

counter) complex experimental setup

variable!substrate

coating

10

E1 = E2 = E3 …


Features of energy-dispersive X-ray diffraction

fixed!

white beam

substrate

Fixed experimental setup Complete diffraction patterns

in fixed directions (unique!) Different diffraction lines Ehkl

originate from different depths

coating

E1 < E2 < E3 …

11


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

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Basic principles of X-ray stress analysis

14


Principle of residual stress analysis by diffraction methods

angle-/energy-dispersive

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1. Measurement of the diffraction line shift for various orientations ( ,j y)

2. Evaluation of the lattice strain

3. Evaluation of the residual stress tensor via Hooke‘s law.


The sin2 -y method

0 1

In-plane homogeneous film with biaxial residual stress state:

Fundamental equation of X-ray stress analysis takes the form:

Residual stress (s z) require a more sophisticated treatment ...

m > 0: tensile stress

m < 0: compressive stress

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XSA on coated cutting tools

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XSA on multilayer systems: Influence of the coating design

5µmWC

TiCNAl2O3

WCTiCN

Al2O3

10µm

„Thin“system (D = 5 µm) „Thick“system (D = 18 µm)

TiCN

0.2 0.4 0.6 0.8 1 0.0873

0.0875

0.0877

0

d42

2[n

m]

sin²

blasted

as-grown

0.2 0.4 0.6 0.8 1 0.0873

0.0875

0.0877

0

d42

2[n

m]

sin²

blasted

as-grown

0.2 0.4 0.6 0.8 1

0.08750

0.08755

0.08760

0

d422

[nm

]

sin²

blasted

as-grown

0.2 0.4 0.6 0.8 1

0.08750

0.08755

0.08760

0

d422

[nm

]

sin²

blasted

as-grown

CuKa

Al2O

3

0.2 0.4 0.6 0.8 1

0.172

0.174

0.176

0

d024

[nm

]

sin²

blasted

as-grown

0.2 0.4 0.6 0.8 1

0.172

0.174

0.176

0

d024

[nm

]

sin²

blasted

as-grown

0.2 0.4 0.6 0.8 1

0.1715

0.1725

0.1735

0.1745

0

d024

[nm

]

sin²

blasted

as-grown

0.2 0.4 0.6 0.8 1

0.1715

0.1725

0.1735

0.1745

0

d024

[nm

]

sin²

blasted

as-grown

CuKasteep stress gradient!


ED-XSA in the interfacial substrate zone

30 40 50 60

200

400

600

800

1000

E [keV]

I [ct

s]

001-

WC

101-

WC

110-

WC

002-

WC

111-

WC

100-

WC

coating reflections

30 40 50 60

200

400

600

800

1000

E [keV]

I [ct

s]

001-

WC

101-

WC

110-

WC

002-

WC

111-

WC

100-

WC

coating reflections

2q = 9°2q = 9°

5µmWC

TiCN

Al2O3

E1 < E2 < E3

M. Klaus et al., Thin solid films 517 (2008), 1172.

1 2 3 4 5 6 7

-1.5

-1.0

- 0.5

0

001

111

002

110

101

001

0

||[G

Pa]

[µm]

blasted

as-grown

1 2 3 4 5 6 7

-1.5

-1.0

- 0.5

0

001

111

002

110

101

001

0

||[G

Pa]

[µm]

blasted

as-grown

coating

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Application of the sin2y-method to each line Ehkl

Assignment of the obtained stress values <shkl> to average information depth <thkl>


5µmWC

TiCNAl2O3

z [µm]

4 8 12 16 20

- 6

- 4

- 2

0

2

0

- 8

||

[GP

a] TiCN

TiN

Al O 3

BL

as-grown

blasted

2

WCTiCN

Al2O3

10µm

z [µm]

1 2 3 4 5

- 6

- 4

- 2

0

2

0

- 8

||

[GP

a]

TiCN

TiN

Al O B

L

as-grown

blasted

2 3

1 2 3 4 5 6 7

-1.5

-1.0

- 0.5

0

001

111

002

110

101

001

0

||[G

Pa]

[µm]

blasted

as-grown

1 2 3 4 5 6 7

-1.5

-1.0

- 0.5

0

001

111

002

110

101

001

0

||[G

Pa]

[µm]

blasted

as-grown

1 2 3 5 6 7

-1.5

-1.0

-0.5

0

111

002

110

101

001

0 4

||[M

Pa]

[µm]

blasted

unblasted

1 2 3 5 6 7

-1.5

-1.0

-0.5

0

111

002

110

101

001

0 4

||[M

Pa]

[µm]

blasted

unblasted

Interlayer gradient: Balance between coating and substrate

Intralayer gradient: Balance within the Al2O3 top layer

Residual stress balance in multilayer systems

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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014 21

Separation of residual stress and composition gradients


Residual stress analysis in expanded austenite layers

2q = 8°

111-N

111

200-N 200

Substrate

Exp. austenite

S. Jegou et al. Thin solid films 530 (2013), 71.

Residual stress (-N) Composition (-N) Strain depth profiling

in the scattering vec-tor mode.

Application of the sin² method for predefined depths .

t = 5 µmm

sin2y*

d0


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

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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

CopperMolybdenium

Glass

metallic precursor

CuInS2

Sulfur

DE


The two-detector setup @ EDDI

Simultaneous acquisition of diffraction patterns in fixed but arbitrary measuring directions!

High resolution In-situ

sin²y

dy

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In-situ analysis of thermal stresses in thin Mo films on glass

Ch. Genzel et al., J. Strain Analysis 46 (2011), 615

Mo = 510-6 K-1 / Glass = 9.510-6 K-1

sin2y-based stress analysis

Ds

26


What can we learn about the microstructure?

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XIII Brazilian MRS meeting, João Pessoa, Brazil, September 28 – October 02, 2014 28

In-situ microstructure analysis: recrystallization of CuInS2

10 50 100 150 Process time [min]

Ene

rgy

[keV

]

30

Substrate temperature [ºC]50 150 250 350 450

Recrystal-lization

H. Rodriguez-Alvarez, PhD thesis, TU Berlin, 2010.

112- CuInS2

Small-grained, defective CuInS2

Recrystallized CuInS2

Driving Forces?Enhancement?

112- CuInS2

29 30 31 32 33Energy [keV]

Lorentzian, broad

Nor

mal

ized

Int

ensi

ty [

a. u

.]

Gaussian, small

Energy-dispersive diffraction line profile analysis?


Instrumental resolution in ED diffraction (EDDI beamline)

Instrumental resolution:

( G – Full width at half maximum)

LaB6 SRM660b Energy-dispersive RIETVELD refinement:

D. Apel et al., Z. Kristallogr. 226 (2011), 943.

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Multiple vs. single line analysis

2 = 10°CeO2 ED Rietveld study of size-related

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 33Energy [keV]

Nor

mal

ized

Int

ensi

ty [

a. u

.]

Energy [keV]

Inte

nsity

[co

unts

x 1

03 ] Needs single line analysis!

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Single line analysis of domain size and microstrain

D. Thomas, PhD thesis, TU Berlin, 2012.

Broadening angle dispersive energy dispersive

Size

Strain

Size and strain broa-dening depend on q!

Only strain broade-ning depends on E!

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

dom

ain

size

[nm

]

interrupt temperature [°C]

mic

ro s

trai

n [%

]

initial state

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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 processeso Microstructural characterization (ED line profile analysis)o ...

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My special thanks go to:Manuela KlausIngwer A. DenksRodrigo CoelhoDaniel ApelDiana ThomasMatthias MeixnerTillman FussGuido Wagener

Roland MainzHumberto Rodriguez-Alvarez

Davor Balzar

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Thank you very much for your attention!

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