AVS 51st International Symposium
    MEMS and NEMS Monday Sessions
       Session MN-MoM

Paper MN-MoM9
Vapor Phase Uptake of Mobile Organophosphates for MEMS Lubrication Purposes

Monday, November 15, 2004, 11:00 am, Room 213C

Session: Processing and Characterization for MEMS and NEMS
Presenter: D.A. Hook, North Carolina State University
Authors: D.A. Hook, North Carolina State University
W. Neeyakorn, North Carolina State University
C. Jaye, North Carolina State University
J. Krim, North Carolina State University
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MEMS devices are highly susceptible to surface forces that can cause suspended members to deflect towards the substrate, collapse and/or adhere permanently to the substrate. A number of surface treatments have met with varying degrees of success for alleviation of MEMS-related stiction/adhesion problems, but friction and wear remain problematic. We report here the results of a quartz crystal microbalance (QCM) study of the nanodynamics and uptake characteristics of organophosphate (tricresylphosphate and t-butyl phenyl phosphate) layers adsorbed from the vapor phase onto silicon and silane treated silicon surfaces. Silanes applied from the liquid phase as self-assembled monolayers are in common use as anti-stiction treatments for silicon MEMS devices, but degrade at elevated temperatures. Organophosphates are highly stable at temperatures in excess of 600ï,°C, act as antioxidants, and have well-documented tribological performance for certain materials combinations. We observe that organophosphates adsorb readily onto selected silanes. The silane +organophosphate combinations moreover exhibit interfacial slippage and/or viscoelasticity in response to the oscillatory motion of the QCM. Such effects have previously been linked to beneficial tribological performance.[1] Work is in progress to assess the tribological performance of these materials on actual MEMS devices. Work supported by AFOSR and NSF. @FootnoteText@ @footnote 1@M. Abdelmaksoud, J.Bender and J. Krim, Phys. Rev. Lett. 92, 176101 (2004).