The mechanical properties of the thin film materials used in RF-MEMS are crucial for the reliability and proper functioning of the devices. In this paper we study a large number of aluminum alloys as possible RF-MEMS thin film materials. The yield strength and creep properties are measured using nano-indentation. The results show that the mechanical properties of thin aluminum films can be improved substantially by alloying elements. Of the alloys studied in this paper, AlCuMgMn in particular seems quite promising as a thin film material for RF MEMS, having both high yield strength and little creep. Using X-ray diffraction and electron microscopy, the observed effects are partly explained.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
J.T.M. van Beek et al., Proc. MRS Symp. Proc. Vol 783, paper B3.1.1, MRS Fall Meeting, Boston (2003).
L.F. Mondolfo, Aluminium Alloys, Structure & properties, Butterworths, (1976).
W. Nix, Metall. Trans. A 20a, 2217 (1989).
J. Malzbender, J.M.J. den Toonder, A.R. Balkenende, G. de With, Mat. Sci. Eng. R, 267, 1 (2002).
D. Tabor, The Hardness of Metals, Oxford Univ. Press, (1951).
M.J. Mayo & W.D. Nix, Proc. of the 8th Int. Conf. on the Strength of Materials, p. 1415, (1988).
D. Pecker: The Strengthening of Metals, Reinhold Publishing Corporation, (1964).
R.W. Evans and B. Wilshire, Creep of metals and alloys, The Institute of Metals, 1985.
R. Modlinski, A. Witvrouw, P. Ratchev, R. Puers, J.M.J. den Toonder & I. De Wolf: “Creep characterization of Al alloy thin films for use in RF-MEMS switches”, MAM2004 conference, Brussels, March (2004).
W.A. Soer, J.Th.M. De Hosson, A.M. Minor, E.A. Stach, J.W. Morris MRS Symp. Proc. Vol 795, paper U9.3.1, MRS Fall Meeting, Boston (2003).
This work is supported by the EC project MEMS2TUNE (IST 28231). Thanks go to Robert Modlinski, Petar Ratchev, and Ingrid de Wolf of IMEC for TEM measurements and discussions.
About this article
Cite this article
den Toonder, J.M., van Dijken, A.R. Optimization of mechanical properties of thin free-standing metal films for RF-MEMS. MRS Online Proceedings Library 820, 13–18 (2004). https://doi.org/10.1557/PROC-820-O8.3