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Alternative dielectric films for rf MEMS capacitive switches deposited using atomic layer deposited Al2O3/ZnO alloys

Herrmann, Cari F. and DelRio, Frank W. and Miller, David C. and George, Steven M. and Bright, Victor M. and Ebel, Jack L. and Strawser, Richard E. and Cortez, Rebecca and Leedy, Kevin D. (2007) Alternative dielectric films for rf MEMS capacitive switches deposited using atomic layer deposited Al2O3/ZnO alloys. Sensors and Actuators A: Physical, 135 (1). 262 - 272.

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Official URL: http://www.sciencedirect.com/science/article/B6THG...

Abstract

Atomic layer deposition (ALD) was used to deposit an alternative dielectric barrier layer for use in radio frequency microelectromechanical systems (rf MEMS). The layer is an alloy mixture of Al2O3 and ZnO and is proposed for use as charge dissipative layers in which the dielectric constant is significant enough to provide a large down-state capacitance while the resistivity is sufficiently low to promote the dissipation of trapped charges. This paper investigates Al2O3/ZnO ALD alloys deposited at 100 and 177 °C and compares their material properties. Auger electron spectroscopy was used to determine the Zn concentrations in the alloy films, which was lower than expected. Atomic force microscopy images revealed an average surface roughness of 0.27 nm that was independent of deposition temperature and film composition. The dielectric constants of the Al2O3/ZnO ALD alloys films were calculated to be similar to pure Al2O3 ALD, being 7. Indentation was used to ascertain the modulus and hardness of the ALD films. Both the modulus and hardness were found to increase for the greater deposition temperature. ALD-coated rf MEMS switches showed a low insertion loss, 0.35 dB, and a high isolation, 55 dB at 14 GHz. Mechanical actuation of the ALD-coated devices showed lifetimes of over 1 billion cycles.

Item Type:Article
Additional Information:Special Issue of The Micromechanics section of Sensors and Actuators (SAMM, based on contributions revised from the Technical Digest of the IEEE 19th International conference on Micro Electro Mechanical Systems (MEMS 2006), 19th International Conference on Micro Electro Mechanical Systems (MEMS-2006)
Uncontrolled Keywords:Atomic layer deposition; Capacitive shunt switch; Dielectric layer; rf MEMS
Subjects:Analytical Science > Nanotechnology for sensing and actuating
Material Science > Nanostructured materials
Engineering > Nanotechnology applications in ICT
ID Code:4827
Deposited By:SPI
Deposited On:29 Apr 2009 10:15
Last Modified:29 Apr 2009 10:15

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