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Investigation of AuNi5 Films Deposited by Pulsed Laser Deposition for RF MEMS Switch Contacts

Published online by Cambridge University Press:  26 February 2011

Noha Farghal
Affiliation:, The American University in Cairo, Yousef Jameel Science and Technology Research Center, 139 Al Haram Street, Giza, 00000000000, Egypt
Moustafa Yehia Ghannam
Affiliation:, Kuwait University, EE Department, Kuwait City, N/A, Kuwait
Amr M. Shaarawi
Affiliation:, the American University in Cairo, Yousef Jameel Science and Technology Research Center, Cairo, N/A, Egypt
Hussein El Samman
Affiliation:, Menoufia University, Physics Department, Shibin, N/A, Egypt
Philippe Soussan
Affiliation:, IMEC v.z.w., Leuven, N/A, Belgium
Kris Baert
Affiliation:, IMEC v.z.w., Leuven, N/A, Belgium
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In this work, the material properties of AuNi5 films prepared by Pulsed Laser Deposition (PLD) to be used as contact materials in RF MEMS switches are investigated. PLD is used because it provides good wide range thickness control (few nanometers to tens of microns) while preserving ablation target stoichiometry. Films with thickness in the range 50 - 450 nm were deposited at Laser energy density (fluence) in the range 0.55 - 1.38 on silicon substrates at room temperature. An aperture was placed between the plume and the substrate to filter out large particulates. The presence of the aperture reduced surface roughness from 8.5 nm to 4.3 nm as determined by optical profilometry. In addition, the presence of the aperture during deposition has been found to affect film stoichiometry. The latter was evaluated using X-ray Fluorescence and the Nickel content has been found to vary in the range 1.1 - 9.5%. Only films deposited with the aperture removed maintain target stoichiometry (5.2% Ni). Hence, it is believed that the presence of the aperture causes non-congruent transfer. The Nickel content within the range under investigation has practically no effect on film morphology or hardness. Laser fluence, however, has been found to be the dominant factor determining film properties. Finally, 100 µm wide AuNi5 strips 290 nm and 130 nm thick deposited at room temperature have been successfully formed on silicon wafers by lift-off photolithography.

Research Article
Copyright © Materials Research Society 2007

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