Instrumentation Errors in

Nano-Indentation

David J Munoz-Paniagua

Motivation

Ever increasing interest in microscopic machines demands a better understanding of the interactions of materials at sub-micron levels. This, combined with the fact that many technologically relevant materials are heterogeneous on a nanometer-micrometer length scale means that the study of the interactions of such materials requires the combination of reliable force measurements with imaging.

Topografiner -1972Scanning Tunnelling Microscope (STM) -1981Atomic Force Microscope (AFM) -1986Interfacial Force Microscope (IFM) -1991

Scanning probe microscopes have been around for a

number of years and are ideal for this task as they

provide a relatively inexpensive way to perform high

resolution imaging, can use different interactions as

their input signal and can be also used for

investigating the nano-mechanical properties of

materials.

at rest coming in contact

“snap-in”

Typical cantilever behaviour

compliance

during indentation

Distance

Force

4.

Indentation Sequence

2.

0. 1.Imaging

3.

5.

0

-5.5Distance

Fo

rce

Elastic

response

Onset of

plasticity

Elasto-Plastic

response

iii

iii

i) Work lost in plastic

deformation.

ii) Work recovered

elastically.

iii) Depth of residual

indent.

Where does the IFM force range fall?

1E-3 1E-6 1E-9 1E-12 1E-15

N

IFM

Casimir

Van der Waals

H bonds

Ionic bonds

Covalent bonds

DNA Stretching

Cell adhesion

Spin Flip

0 8µN

0

200

nm

1 2 3

Graham, J.F., McCague, C., Norton, P.R., Tribol. Lett. 6, 149 (1999)

IFM Nano-indentation of Alkyl ZDDP tribofilm on steel

(nm)

2 1 31 = 92 GPa

2 = 209 GPa

3 = 84 GPa

Distance [nm]

Force [µN]

0

5

10

15

20

25

0 5 10 15 20 25 30Distance [nm]

For

ce [

µN

]

400nm x 400nm

IFM Nano-indentation on Au ‹111›

78 GPa

IFM Nano-indentation on Kevlar12 x 12 µm2

core

skin

3 x 3 µm2

0

20

40

60

80

0 30 60 90 120

Distance [nm]

Forc

e [µ

N]

epoxy

62 GPa 13 GPa

2.5 GPa

Graham, J.F., McCague, C., Warren, O.L., Norton, P.R., Polymer 41, 4761 (2001)

0

10

20

30

40

50

20 nm

Force (µN)

Distance

Cleaved

7.8 GPa

Annealled

12.1 GPa

IFM Nano-indentation on PET

A SEM image of a tungsten

probe after indentation on

polyurethane.

-2

-1

0

1

2

3

4

5

6

0 50 100 150 200 250

Distance [nm]

Force [µN]

loading unloading

Indentation on polyurethane showing evidence of

transfer of material onto the probe.

IFM Nano-indentation on PU

b)

c)

a) Images taken on Polyurethane using TappingMode-IFM

a) 6µm×6µm Tapping Mode scan after a 3µm×3µm Contact Mode scan.

b) Same spot rotated by 90°. (6µm×6µm)

c) 9µm×9µm Tapping Mode scan after several Tapping Mode scans at 6µm×6µm.

Amplitude Phase

0

For

ce

Distance

23

21

*

3

4DREF =

max

max

A

FH =

*2 EA

dD

dFS

π==

compliancescanner DDD −=

Instrument Development

The closed loop stage design has been finalized and is been fabricated. This will give us sub-Åresolution on the distance axis.

Instrument DevelopmentCollaboration with Walied Moussa (U of A – Mech Eng)

Else Gallagher is working on the first batch of prototype sensors. The mask design has been finalized as of last week. Each wafer will contain roughly 200 sensors divided between 12 separate designs.

Instrument Development

We have proposed a sensor redesign that would allow us to monitor the system compliance in real time using our fibre interferometer.

Interferometry

Differential

Capacitance

Electrostatic

Feedback

4aF/√√√√Hz0.17µV/√√√√Hz

0

0

Force

Displacement

Hertz

0

0

Force

Displacement

Hertz

JKR

DMT

Fitting the approach curve

23

21

*

3

4DREF =

RDREF πγ23

423

21

* −=

*

2

*33*

2)(

83

4)(

E

a

R

aaD

EaR

aEF

πγ

γπα

−=

−=

0

0

Force

Displacement

Hertz

DMT

122

* 11−

−−

−=

i

i

s

s

EEE

νν

*2 EA

dh

dPS

π==

Oliver, W. C.; Pharr, G. M. Journal of Materials

Research 1992, 7, 1564.

Fitting the retraction curve1

22* 11

−

−−

−=

i

i

s

s

EEE

νν

iit CAE

CS

C +=+=π

β *2

11

Both parameters are determined via

nano-indentation experiments and are

interdependent. May not obtain a

unique solution.

max

max

A

FH =

Direct AFM determination of Tip Shape-Area function

Shape-area function

Description of a worn indenter

Cone

Cone + Sphere (floating)

Cone + Sphere (tangential)

Cone + Sphere (tangential + harmonic average)

Cone + Sphere (piecewise combination usingfiltering techniques)

Hyperboloid of revolution

The IFM

To God Almighty

P. R. Norton

L. L. Coatsworth

S. Tadayyon

C. M. McCague (SFU)

UWO Physics

Machine shop

UWO Chemistry

Electronics shop

M. T. McDermott

(NRC-NINT)

W. Moussa (UofA)

T. Veres (NRC-IMI)

J. Decker (NRC-INMS)

J. E. Houston (SNL)

R. Winter (SDSMT)

UofA NanoFab