The effects of moisture on thin film delamination and adhesion

102 Pages·2015·4.33 MB·English

by  Patrick Waters

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USF Tampa Graduate Theses and Dissertations USF Graduate Theses and Dissertations
3-28-2005
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Patrick Waters
University of South Florida
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Graduate Theses and Dissertations.
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The Effects Of Moisture On Thin Film Delamination And Adhesion

by

Patrick Waters

A thesis submitted in partial fulfillment
of the requirements for the degree of
Masters of Science in Mechanical Engineering
Department of Mechanical Engineering
College of Engineering
University of South Florida

Major Professor: Alex Volinsky, Ph.D.
Thomas Eason, Ph.D.
Autar Kaw, Ph.D.

Date of Approval:
March 28, 2005

Keywords: Copper, Diamond like Carbon, Nanoindentation, Environmentally Assisted
Fracture

©Copyrght 2005, Patrick Waters
DEDICATION
To my parents, this would not have been possible without their support.
ACKNOWLEDGEMENTS
I would like to thank my advisor Dr. Alex Volinsky for his support and guidance
throughout my research. I am very grateful for the help and advice my committee
members Dr. Eason and Dr. Kaw have given me since my days as an undergraduate. I
would also like to thank the rest of the faculty and staff in the mechanical engineering
department for being a friendly and positive influence. I want to acknowledge Seagate
for providing samples and a special thanks to NACE for funding my research.
TABLE OF CONTENTS

TABLE OF CONTENTS.....................................................................................................i

LIST OF TABLES.............................................................................................................iii

LIST OF FIGURES...........................................................................................................iv

ABSTRACT......................................................................................................................vii

CHAPTER 1.......................................................................................................................1
INTRODUCTION..............................................................................................................1
1.1 Thin film technology...............................................................................................1
1.2 Adhesion.................................................................................................................2
1.3 Fracture criterion.....................................................................................................5
1.4 Literature review.....................................................................................................9
1.4.1 Environmentally assisted fracture.................................................................10
1.4.2 Water vapor effects on soda-lime glass fracture...........................................10
1.4.3 Moisture effects in thin films........................................................................13

CHAPTER 2.....................................................................................................................18
THIN FILM DEPOSITION AND MECHANICAL CHARACTERIZATION...............18
2.1 Methods for depositing thin films.........................................................................18
2.1.1 Physical vapor deposition (PVD)..................................................................18
2.1.2 Chemical vapor deposition (CVD)...............................................................20
2.1.3 Electroplating................................................................................................21
2.2 Modulus and hardness measurements by nanoindentation...................................22
2.3 Thin film adhesion tests........................................................................................26
2.3.1 Scratch test....................................................................................................26
2.3.2 Four-point bend test......................................................................................27
2.3.3 One-dimensional buckling analysis..............................................................30
2.3.4 Indentation test..............................................................................................32
2.4 Residual stresses...................................................................................................39
2.4.1 Stoney’s equation..........................................................................................40
2.4.2 X-ray diffraction for stress determination.....................................................41

CHAPTER 3.....................................................................................................................44
ADHESION MEASUREMENTS....................................................................................44
3.1 Sample preparation...............................................................................................44
3.2 Adhesion measurements in a dry environment.....................................................45
3.3 Effects of indenter tip geometry on adhesion measurements...............................52
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3.4 Double indent test.................................................................................................55
3.5 Adhesion measurements in a wet environment....................................................57
3.6 Substrate fracture and film buckling.....................................................................63
3.7 Reduction in adhesion...........................................................................................65

CHAPTER 4.....................................................................................................................68
FLUID TRANSPORT THROUGH DELAMINATIONS................................................68
4.1 Telephone cord delamination propagation............................................................68
4.2 Microfluidic application of telephone cord delamination blisters........................75
4.3 Fluid flow in microchannels.................................................................................78

CHAPTER 5.....................................................................................................................81
SUMMARY AND FUTURE WORK..............................................................................81
5.1 Summary...............................................................................................................81
5.2 Various environmental effects..............................................................................81
5.3 Radial cracking.....................................................................................................82
5.4 Biaxial film stress.................................................................................................82
5.6 Microfluidic applications......................................................................................83
5.7 Crack propagation rates........................................................................................84

REFERENCES.................................................................................................................87

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LIST OF TABLES

Table 1. Strain energy release rates in dry environment...................................................51

Table 2. Adhesion of thin films in dry environment.........................................................52

Table 3. Double and single indent adhesion results in dry environment..........................57

Table 4. Adhesion of thin films in wet environment........................................................62

Table 5. Propagation rates of various fluids in DLC sample............................................74

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LIST OF FIGURES

Figure 1. Contact angle technique......................................................................................3

Figure 2. Modes of fracture: a) Mode I b) Mode II c) Mode III.........................................7

Figure 3. Strain energy release rate as a function of Ψ.......................................................9

Figure 4. Blister dimensions...............................................................................................9

Figure 5. Schematic of double cantilever cleavage test....................................................11

Figure 6. Dependence of crack velocity on relative humidity adapted from
Wiederhorn’ experiments [17]..........................................................................13

Figure 7. Delamination of silver backing on a mirror......................................................15

Figure 8. Schematic of a RF sputtering system................................................................19

Figure 9. Schematic of an electroplating system..............................................................21

Figure 10. Hysitron three plate capacitor transducer........................................................22

Figure 11. Load-displacement curve used to calculate the film modulus and
hardness..........................................................................................................24

Figure 12. Topographic scan of an indent made in single crystal Al...............................25

Figure 13. Schematic of a four-point bend test.................................................................28

Figure 14. Trend in steady state strain energy release rates with the film
thickness and modulus ratios [36]..................................................................29

Figure 15. One-dimensional buckle schematic: a) Residually stressed thin film,
b) Forces applied to a thin film.......................................................................31

Figure 16. Hypothetical operations used to calculate the strain energy associated
with an indentation-induced delamination in a stressed film.........................33

Figure 17. Delamination blister produced in the superlayer indentation test...................37
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Figure 18. Load-displacement curve for plastic indentation depth determination...........38

Figure 19. Nanoindenter with a multirange transducer....................................................39

Figure 20. Residual stress map of a 1 µm W film on a 6” Si wafer [38]..........................40

Figure 21. Sin2Ψ technique setup.....................................................................................42

Figure 22. Strained lattice spacing vs. sin2Ψ for a tungsten thin film..............................43

Figure 23. X-ray data for (220) tungsten film...................................................................43

Figure 24. Load-displacement curves for a 97 nm thick copper film...............................46

Figure 25. Radial cracks in delamination blister..............................................................47

Figure 26. Shift in load-displacement curve.....................................................................48

Figure 27. Definition x/a dimensions................................................................................49

Figure 28. Strain energy release rates for the 67 nm thick copper film............................49

Figure 29. Strain energy release rates for the 97nm thick copper film.............................50

Figure 30. Strain energy release rates for the 5 nm thick DLC film.................................50

Figure 31. Delamination induced by a Berkovich tip.......................................................53

Figure 32. Asymmetrical delamination blisters made with Berkovich tip.......................55

Figure 33. Double indent versus single indent in dry environment..................................56

Figure 34. Telephone cord delamination induced in DCL film by water and
indentation......................................................................................................58

Figure 35. Telephone cord delamination..........................................................................59

Figure 36. Indents in the 67nm thick copper film in dry and wet environments..............60

Figure 37. Schematic of necessary penetration depth for water to induce delamination. 61

Figure 38. Asymmetrical blister shape of the 97 nm thick copper film...........................61

Figure 39. Double indent in wet environment..................................................................63

Figure 40. Load excursions in wet and dry environments................................................64
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Figure 41. Substrate and film fracture patterns.................................................................64

Figure 42. Buckling patterns in compressed films [60]....................................................69

Figure 43. Blister height profile........................................................................................70

Figure 44. Transition from straight-sided blister to sinusoidal shape...............................71

Figure 45. Telephone cord propagation induced by water introduction...........................72

Figure 46. Water exiting a telephone cord delamination..................................................73

Figure 47. Telephone cord propagation............................................................................75

Figure 48. Microprobe manipulation of telephone cord delamination.............................77

Figure 49. Microprobe setup.............................................................................................78

Figure 50. Fluid flow in delamination channel.................................................................78

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