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Alloy Thin Films by Multi-Target Sputtering
Karla L. PerezMSE/REU
Final PresentationAdv. Prof. King and Prof. Dayananda
August 5, 2004
Overview
• Introduction• Research Project• Processing• Measuring Film Thickness
– Optical Microscope– AFM
• Alloy Thin Film Deposition– Composition
• Conclusion
Application of Thin Films
• Antireflection coatings for camera lenses
• Optical filters for communication• Decorative coatings on plastics • Silicon chips• Metallic coatings• To provide insulating layers between
conductors
Research Project• The main goal is to create alloy thin films with uniform composition
and thickness• Study the compositions of pure metal thin films and their thickness • Pure metal components to be used: Ag, Cu, Ta, Mo, Ni, Fe, Ti• Design a system which will enable us to manage the composition
and geometry of the alloy thin films
Processing
• SputteringIt is a type of Physical Vapor Deposition. It is carried out at high vacuum in a chamber connected to a high voltage DC supply.Argon gas is pumped into the chamber and creates argon plasma. The Argon plasma is directed to the target and its atoms are vaporized. The vaporized material is then deposited on the substrate.
Measuring Film Thickness
• Optical Microscope– Differential Interference Contrast (DIC)
Ag 20min 4cm
Measuring Film ThicknessOptical Microscope
Cu 10min 4cm Ag 20min 4cm
Measuring Film ThicknessOptical Microscope
Ag 10 min 4cm Ag 20min 4cm
Measuring Film Thickness• Atomic Force Microscope (AFM)
– Tapping mode: Measures the topography by tapping the surface with an oscillating tip. This eliminates the shear forces which can damage soft samples and reduce image resolution.
Measuring Film Thickness
Measuring Film ThicknessAFM
Ag 20min 2cm
Measuring Film ThicknessAFM
Mo 30min 2cm
Measuring Film ThicknessAFM
Cu 30min 2cm
Ag 30min 2cm
Number of Unit Cells Deposited per Minute
0
10
20
30
40
50
60
1 2 3 5 6 9 10 11 12 13 14 15 16
Position on slide
Tim
e
Number of Cells Depositedper Minute
14.19
52.40
Alloy Thin Film Deposition
• Deposit alloy thin films using a sputter coater with a Copper-Silver target
Composition of Ag-Cu Thin Film
Ag-Cu composition
0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Position in slide
mo
le w
t%
Ag
Cu
92.7%
7.3%
50.3%
Position on slide
Composition of Ag-Cu Thin Film
Ag-Cu concentration wt%
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Position in slide
co
nc
en
tra
tio
n w
t%
Ag
Cu
95.6%
4.4%
50.3%
Position on slide
Conclusion
• The thickness of the film varies according to their position relative to the target.
• Films deposited are thicker in the middle.
• Deposited one alloy thin film• The same composition gradients of
silver and copper do not occur in the middle of the film.
Acknowledgements
• Prof. King
• Prof. Dayananda
• Prof. Kvam
• NSF Grant
Questions???
Thank you!!!