Vapor Phase Lubrication of Gold/Gold Interfaces

The extension of current micro-satellite development efforts calls for a reduction in size by up to two orders of magnitude. Such a reduction in size necessitates the development of novel actuators, switches, and sensors operating on the micron length scale. The leading technology for creating such devices involves microfabrication processes currently used in the production of integrated circuits. Devices generated by these means are referred to as Micro-Electro-Mechanical Systems (MEMS). While many challenges remain in the design and production of MEMS, a critical aspect of their successful deployment involves lubrication of the devices to prevent wear and permanent, undesired adhesion (seizure) of the miniature moving parts. Results from research addressing the vapor phase lubrication of gold-gold contacts, modeling interfaces expected to be encountered in future RF MEMS devices, will be presented. Such interfaces will require high frequency intermittent contact, the absence of irreversible interfacial adhesion, the general absence of sliding within the contact, and the requirement of electrical conductivity upon contact. Work in this area has focused on the use of alklythiols as a means of controlling interfacial adhesion. Experiments have been carried out using atomic force microscopy to characterize adhesion as a function of alkylthiol chain length. In addition, these experiments have incorporated the simultaneous measurement of interfacial currents to explore load versus conductivity relationships. These measurements have been supported through measurements of surface composition through correlated quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) measurements.