Enhanced Reliability and Performance of MEMS Devices

Micro electromechanical systems (MEMS) devices are developing rapidly for a variety of applications. MEMS devices are fabricated using silicon micro-machining. The resultant MEMS devices suffer reliability problems because of mechanical wear between the moving parts and because of stiction from attractive surface forces and static charge buildup. Many of these reliability problems could be solved by applying the appropriate thin film coating to the MEMS device.

ALD is ideal for the deposition of conformal films on the high aspect ratio structures encountered in MEMS devices. Our research has demonstrated that Al2O3 ALD yields a hard and protective coating that reduces abrasive wear in MEMS devices [1]. Nanolaminates can also provide films with enhanced hardness to minimize further mechanical wear. In addition, Al2O3/ZnO alloys have been shown to provide a variable resistivity film that can dissipate static charge and minimize stiction. The wide range of resistivities achieved by Al2O3/ZnO alloys is shown in the accompanying figure [2].

References

  1. T.M. Mayer, J.W. Elam, S.M. George and P.G. Kotula, "Atomic Layer Deposition of Wear-Resistant Coatings for Micromechanical Devices", Appl. Phys. Lett. 82, 2883-2885 (2003).
  2. J.W. Elam, D. Routkevitch and S.M. George, "Properties of ZnO/Al2O3 Films Deposited Using Atomic Layer Deposition Techniques", J. Electrochem. Soc. (in press).

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