Tribology Letters

, 44:13 | Cite as

Morphological, Electrical, and Chemical Changes in Cyclically Contacting Polycrystalline Silicon Surfaces Coated with Perfluoroalkylsilane Self-Assembled Monolayer

  • Ian Laboriante
  • Maxwell Fisch
  • Amir Payamipour
  • Fang Liu
  • Carlo Carraro
  • Roya Maboudian
Original Paper


The evolution of morphology, electrical properties, and chemical composition has been studied in cyclically contacting polycrystalline silicon (polysilicon) surfaces coated with perfluoroalkylsilane self-assembled monolayer (SAM). The microinstrument used is a MEMS cantilever that is repeatedly actuated out-of-plane to impact a landing pad and is then moved in-plane to enable nondestructive in situ inspection of the impacted area. Analyses show that a device with a monolayer coating exhibits signs of surface degradation after a much higher number of cycles than its uncoated counterpart. A sharp increase in contact resistance between the cantilever and landing pad is observed at ~10 billion cycles for a coated device, versus ~25 million cycles for an uncoated device. Likewise, the onset of grain fracture in the landing pad occurs at ~25 billion cycles for the SAM-coated device, versus ~3 billion cycles for its uncoated counterpart. The effectiveness of the monolayer coating diminishes after more than 100 billion contact cycles as the SAM layer is removed, and the polysilicon substrate becomes susceptible to adhesive wear.


MEMS reliability Polycrystalline silicon Contact resistance Self-assembled monolayer Multi-asperity contacts Adhesive wear 



The authors thank Nathan Klejwa of Stanford University for the assistance in the AES analysis conducted at Stanford Nanocharacterization Laboratory. This work was supported in part by the Defense Advanced Research Projects Agency (DARPA) N/MEMS S&T Fundamentals program under grant no. N66001-10-1-4004 issued by the Space and Naval Warfare Systems Center Pacific (SPAWAR).


  1. 1.
    Maboudian, R., Carraro, C.: Surface chemistry and tribology of MEMS. Annu. Rev. Phys. Chem. 55, 35 (2004)CrossRefGoogle Scholar
  2. 2.
    Maboudian, R., Ashurst, W.R., Carraro, C.: Tribological challenges in micromechanical systems. Tribol. Lett. 12, 95–100 (2002)CrossRefGoogle Scholar
  3. 3.
    Romig, A.D., Dugger, M.T., McWhorter, P.J.: Materials issues in microelectromechanical devices: science, engineering, manufacturability and reliability. Acta Mater. 51, 5837–5866 (2003)CrossRefGoogle Scholar
  4. 4.
    de Boer, M.P., Mayer, T.M.: Tribology of MEMS. MRS Bull. 26, 302–304 (2001)CrossRefGoogle Scholar
  5. 5.
    Komvopoulos, K.: Surface engineering and microtribology for microelectromechanical systems. Wear 200, 305–327 (1996)CrossRefGoogle Scholar
  6. 6.
    Liu, F., Laboriante, I., Bush, B., Roper, C.S., Carraro, C., Maboudian, R.: 2-Axis MEMS deflecting cantilever microinstrument for in situ reliability studies. 15th International Conference on Solid-State Sensors, Actuators and Microsystems. Transducers 2009, Denver, CO, USA, 21–25 June 2009, pp. 1521–1524Google Scholar
  7. 7.
    Liu, F., Laboriante, I., Bush, B., Roper, C.S., Carraro, C., Maboudian, R.: In situ studies of interfacial contact evolution via a 2-axis deflecting cantilever microinstrument. Appl. Phys. Lett. 95, 131902 (2009)CrossRefGoogle Scholar
  8. 8.
    Hook, D.A., Timpe, S.J., Dugger, M.T., Krim, J.: Tribological degradation of fluorocarbon coated silicon microdevice surfaces in normal and sliding contact. J. Appl. Phys. 104, 034303-1–034303-6 (2008)CrossRefGoogle Scholar
  9. 9.
    Bhushan, B., Kasai, T., Kulik, G., Barbieri, L., Hoffmann, P.: AFM study of perfluoroalkylsilane and alkylsilane self-assembled monolayers for anti-stiction in MEMS/NEMS. Ultramicroscopy 105, 176–188 (2005)CrossRefGoogle Scholar
  10. 10.
    Cichomski, M., Grobelny, J., Celichowski, G.: Preparation and tribological tests of thin fluoroorganic films. Appl. Surf. Sci. 254, 4273–4278 (2008)CrossRefGoogle Scholar
  11. 11.
    Singh, R.A., Kim, J., Yang, S.W., Oh, J.E., Yoon, E.S.: Tribological properties of trichlorosilane-based one- and two-component self-assembled monolayers. Wear 265, 42–48 (2008)CrossRefGoogle Scholar
  12. 12.
    Chang, X., Jones, R.L., Batteas, J.D.: Dynamic variations in adhesion of self-assembled monolayers on nanoasperities probed by atomic force microscopy. Scanning 30, 106–117 (2008)CrossRefGoogle Scholar
  13. 13.
    Guo, L.-Y., Zhao, Y.-P.: Effect of chain length of self-assembled monolayers on adhesion force measurement by AFM. J. Adhes. Sci. Technol. 20, 1281–1293 (2006)CrossRefGoogle Scholar
  14. 14.
    Liu, H.W., Bhushan, B.: Adhesion and friction studies of microelectromechanical systems/nanoelectromechanical systems materials using a novel microtriboapparatus. J. Vac. Sci. Technol. A 21, 1528–1538 (2003)CrossRefGoogle Scholar
  15. 15.
    Ding, J.N., Wong, P.L., Yang, J.C.: Friction and fracture properties of polysilicon coated with self-assembled monolayers. Wear 260, 209–214 (2006)CrossRefGoogle Scholar
  16. 16.
    Miller, B.P., Theodore, N.D., Brukman, M.J., Wahl, K.J., Krim, J.A.: Nano- to macroscale tribological study of PFTS and TCP lubricants for Si MEMS applications. Tribol. Lett. 38, 69–78 (2010)CrossRefGoogle Scholar
  17. 17.
    Maboudian, R., Ashurst, W.R., Carraro, C.: Self-assembled monolayers as anti-stiction coatings for MEMS: characteristics and recent developments. Sens. Actuators A 82, 219–223 (2000)CrossRefGoogle Scholar
  18. 18.
    Mayer, T.M., de Boer, M.P., Shinn, N.D., Clews, P.J., Michalske, T.A.: Chemical vapor deposition of fluoroalkylsilane monolayer films for adhesion control in microelectromechanical systems. J. Vac. Sci. Technol. B 18, 2433–2440 (2000)CrossRefGoogle Scholar
  19. 19.
    Ashurst, W.R., Yau, C., Carraro, C., Maboudian, R., Dugger, M.T.: Dichlorodimethylsilane as an anti-stiction monolayer for MEMS: a comparison to the octadecyltrichlosilane self-assembled monolayer. J. Microelectromech. Syst. 10, 41–49 (2001)CrossRefGoogle Scholar
  20. 20.
    Patton, S.T., Cowan, W.D., Eapen, K.C., Zabinski, J.S.: Effect of surface chemistry on the tribological performance of a MEMS electrostatic lateral output motor. Tribol. Lett. 9, 199–209 (2001)CrossRefGoogle Scholar
  21. 21.
    Herrmann, C.F., Delrio, F.W., Bright, V.M., George, S.M.: Conformal hydrophobic coatings prepared using atomic layer deposition seed layers and non-chlorinated hydrophobic precursors. J. Micromech. Microeng. 15, 984–992 (2005)CrossRefGoogle Scholar
  22. 22.
    Flater, E.E., Corwin, A.D., de Boer, M.P., Carpick, R.W.: In situ wear studies of surface micromachined interfaces subject to controlled loading. Wear 260, 580–593 (2006)CrossRefGoogle Scholar
  23. 23.
    Yu, T., Ranganathan, R., Johnson, N., Yadav, N., Gale, R., Dallas, T.: In situ characterization of induced stiction in a MEMS. J. Microelectromech. Syst. 16, 355–364 (2007)CrossRefGoogle Scholar
  24. 24.
    Patton, S.T., Eapen, K.C., Zabinski, J.S., Sanders, J.H., Voevodin, A.A.: Lubrication of microelectromechanical systems radio frequency switch contacts using self-assembled monolayers. J. Appl. Phys. 102, 024903/1–5 (2007)Google Scholar
  25. 25.
    Fréchette, J., Maboudian, R., Carraro, C.: Effect of temperature on in-use stiction of cantilever beams coated with perfluorinated alkysiloxane monolayers. J. Microelectromech. Syst. 15, 737–744 (2006)CrossRefGoogle Scholar
  26. 26.
    Tas, N.R., Gui, C., Elwenspoek, M.: Static friction in elastic adhesion contacts in MEMS. J. Adhes. Sci. Technol. 17, 547–561 (2003)CrossRefGoogle Scholar
  27. 27.
    Henck, S.: Lubrication of digital micromirror devices. Tribol. Lett. 3, 239–247 (1997)CrossRefGoogle Scholar
  28. 28.
    Laboriante, I., Bush, B., Lee, D., Liu, F., King-Liu, T.-J., Carraro, C., Maboudian, R.: Interfacial adhesion between rough surfaces of polycrystalline silicon and its implications for M/NEMS technology. J. Adhes. Sci. Technol. 24, 2545–2556 (2010)CrossRefGoogle Scholar
  29. 29.
    Hayashi, K., Saito, N., Sugimura, H., Takai, O., Nakagiri, N.: Surface potential contrasts between silicon surfaces covered and uncovered with an organosilane self-assembled monolayer. Ultramicroscopy 91, 151–156 (2002)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Ian Laboriante
    • 1
    • 2
  • Maxwell Fisch
    • 1
  • Amir Payamipour
    • 1
  • Fang Liu
    • 1
    • 3
  • Carlo Carraro
    • 1
  • Roya Maboudian
    • 1
  1. 1.Department of Chemical and Biomolecular EngineeringUniversity of CaliforniaBerkeleyUSA
  2. 2.Micron TechnologyBoiseUSA
  3. 3.Analog Devices IncWilmingtonUSA

Personalised recommendations