Abstract
Recent research has established that for silicon structural films used in microelectromechanical systems (MEMS), the susceptibility to premature failure under cyclic fatigue loading originates from a degradation process that is confined to the surface oxide. In ambient air environments, a sequential, stress-assisted oxidation and stress-corrosion cracking process can occur within the native oxide on polycrystalline silicon (referred to as reaction-layer fatigue); for the structural films of micron-scale dimensions, such incipient cracking in the oxide can lead to catastrophic failure of the entire silicon component. Since the degradation process is intimately linked to the thin reaction layer on the silicon, modification of this surface and the access of the environment to it can dramatically alter the fatigue resistance of the material. The purpose of this paper is to evaluate the efficacy of modifying the fatigue behavior of polycrystalline silicon with alkene-based monolayers. Specifically, 2-µm thick polysilicon fatigue structures were coated with a monolayer film based on 1-octadecene and cyclically tested to failure in laboratory air. By applying the coating, the formation of the native oxide was prevented. Compared to the fatigue behavior of untreated polysilicon, the lives of the coated samples ranged from 105 to >1010 cycles at stress amplitudes greater than ~90% of the ultimate strength of the film. The dramatic improvement in fatigue resistance was attributed to the monolayer inhibiting the formation of the native oxide and stress corrosion of the surface. It is concluded that the surprising susceptibility of thin structural silicon films to premature fatigue failure can be inhibited by such monolayer coatings.
Similar content being viewed by others
References
Connally, J.A. and Brown, S.B., Science, 256, 1537–39 (1992).
Kahn, H., Ballarini, R., Mullen, R.L. and Heuer, A.H., Proc. Roy. Soc. A, 455, 3807–23 (1999).
Kapels, H., Aigner, R. and Binder, J., in Proceedings of the 29th European Solid-State Device Research Conference, edited, IEEE, 1999, pp. 1522–28.
Bagdahn, J. and Sharpe, W.N.J., in MEMS 2002, edited, IEEE, 2002, pp. 447–450.
Muhlstein, C.L., Brown, S.B. and Ritchie, R.O., Sens. Actuators A, 94, 177–88 (2001).
Muhlstein, C.L., Stach, E.A. and Ritchie, R.O., Appl. Phys. Let., 80, 1532–1534 (2002).
Muhlstein, C.L., Stach, E.A. and Ritchie, R.O., Acta Mater., in press (2002).
MCNC/Cronos, www.memsrus.com, 2000.
Simmons, G. and Wang, H., Single Crystal Elastic Constants and Calculated Aggregate Properties: a Handbook, 2nd ed., edited by, Press, M.I.T., Cambridge, MA, 1971.
Ballarini, R., Mullen, R.L., Yin, Y., Kahn, H., Stemmer, S. and Heuer, A.H., Adv. Appl. Mech., 12, 915–22 (1997).
Kahn, H., Tayebi, N., Ballarini, R., Mullen, R.L. and Heuer, A.H., Sens. Actuators A, A82, 274–80 (2000).
Muhlstein, C.L., Brown, S.B. and Ritchie, R.O., J. Microelectromech. Sys., 10, 593–600 (2001).
Ashurst, W.R., Yau, C., Carraro, C., Howe, R.T. and Maboudian, R., in Hilton Head Solid-State Sensor and Actuator Workshop, edited, Transducers Res. Found, 2000, pp. 320–23.
Muhlstein, C.L., Howe, R.T. and Ritchie, R.O., Mech. Mater., in review (2002).
Ashurst, W.R., Yau, C., Carraro, C., Maboudian, R. and Dugger, M.T., J. Microelectromech. Sys., 10, 41–49 (2001).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Muhlstein, C.L., Ashurst, W.R., Stach, E.A. et al. Surface Engineering of Polycrystalline Silicon Microelectromechanical Systems for Fatigue Resistance. MRS Online Proceedings Library 729, 21 (2002). https://doi.org/10.1557/PROC-729-U2.1
Published:
DOI: https://doi.org/10.1557/PROC-729-U2.1