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The effect of water vapor on n-pentanol vapor phase lubrication (VPL) was studied with a microelectromechanical system (MEMS) side-wall tribometer, a pin-on-disc tribometer, and attenuated total reflection infrared (ATR-IR) spectroscopy. The n-pentanol vapor pressure was fixed at 50 % relative to its saturation vapor pressure (P sat = ~2.2 Torr at room temperature), which is sufficient to maintain a monolayer of n-pentanol on a SiO2 surface in a dry Ar environment. As the relative humidity (RH) was increased from zero to 30 %, ATR-IR measurements showed that the water adsorption on the surface increases and the adsorbed pentanol thickness decreases by 60 %. These changes in the adsorption isotherm were manifested as higher, and more scattered friction coefficients observed during the MEMS tribometer operation. The maximum RH tolerance appeared to be 25–30 % RH above which the MEMS tribometer failed to operate reliably. In contrast, the n-pentanol VPL efficiency was not affected significantly during the macro-scale pin-on-disc tribometer tests. These results imply that the friction behavior of the asperity contacts in MEMS is more susceptible to co-adsorption of water than the friction behavior of macro-scale contacts.

Three-spatial-dimension (3D) time-of-flight-secondary ion mass spectrometry (TOF-SIMS) analysis can be performed if an X-Y image is saved at each depth of a depth profile. In this paper, we will show how images reconstructed from specified depths, depth profiles generated from specific X-Y coordinates, as well as three-spatial-dimensional rendering provide for a better understanding of the sample than traditional depth profiling where only a single spectrum is collected at each depth. We will also demonstrate, for the first time, that multivariate statistical analysis (MVSA) tools can be used to perform a rapid, unbiased analysis of the entire 3D data set. In the example shown here, retrospective analysis and MVSA revealed a more complete picture of the 3D chemical distribution of the sample than did the as-measured depth profiling alone. Color overlays of the MVSA components as well as animated movies allowing for visualization (in 3D) from various angles will be provided.

Low surface energy coatings and films are needed to minimize stiction, high friction, and wear of the oxide-terminated silicon-based microelectromechanical systems (MEMSs) to ensure reliable device function. One common approach is to deposit self-assembled monolayer (SAM) films of molecules possessing a reactive silane head group and low energy pendant chain to cover the complex structures used in MEMS devices. The composition of these films is difficult to characterize and quantify. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is an excellent tool for characterizing these types of films because of its ability to detect small quantities of surface species at high spatial resolution and surface sensitivity; however, interpretation of the spectral data generated is complex and challenging. We are using the combination of x-ray Photoelectron Spectrometry and ToF-SIMS to detect and quantify a fluorocarbon-based SAM on Si coupons and on MEMS devices. Unexpected fragmentation caused by the interact...

We have fabricated, tested and analyzed the reliability of Pt- and RuO2-coated ohmic microrelays in ultra-high purity gas environments. RuO2-coated relays could survive 3 × 108 contact cycles without electrical degradation, while Pt-coated devices degraded after 105 cycles. Thermally actuated microrelays were fabricated using a process that employed a polysilicon surface-micromachined substructure. After releasing the devices, just a few blanket metal depositions were required to create the different coatings. This method allowed direct comparisons between different coating materials, and was enabled by a self-aligned shadow mask that provides electrical isolation between different traces. Testing was performed in a clean environment achieved through in situ ultra-high vacuum bakeouts, chamber cooling to