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• Sputtering

It 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 2cmNumber 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 FilmAg-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

mol

e w

t%

AgCu

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

conc

entr

atio

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!!!