This paper describes a processing method which allows for theapplication of a dichlorodimethylsilane (DDMS) anti-stiction monolayertoMEMS on a wafer scale from the vapor phase. This processingmethod represents significant advantages over the existing liquidbased coating technologies (e.g., OTS and FDTS self assembledmonolayers (SAMs) [1]) for a variety of reasons. Earlier SAMs,especially FDTS, are susceptible to high levels of particulate contamination.Additionally, SAMs based on OTS or alkene (e.g., octadecene)chemistries suffer from low thermal stability (up to about225 C in air)[2]. However, monolayers formed using DDMS havethe unique combination of low particle susceptibility and high thermalstability (upwards of 425 C in air) [3]. By utilizing vaporphase (dry) processing, the problems associated with liquid processingsuch as scale-up, chemical and substrate handling and processcontrol, can be overcome.We have designed and built a reactor system that allows for thevapor phase deposition of a variety of monolayer systems on both dieand wafer levels. Primarily, this system has been used to study thedeposition of DDMS monolayers. First, released microstructures areintroduced to the vessel. Then in situ cleaning of the microstructures(as well as the reactor vessel) with a down-stream water (or oxygen)plasma is performed. The reactive precursor is dosed and the surfacereaction is carried out. The structures are then ready to be removedfrom the system and tested.We have evaluated vapor deposited DDMS films in a numberof ways. Contact angle analysis, X-ray photoelectron spectroscopy(XPS) and atomic force microscopy (AFM) have been used to characterizethe film on Si(100). Film properties such as work of adhesionand coefficient of static friction were measured from coatedmicromachine test structures. It is shown that the DDMS monolayerdeposited from the vapor phase is quite effective at reducing adhesionand friction.
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