Electrically Conductive Self-Assembled Monolayer (SAM) Anti-Stiction Coating for Micro-Electromechanical Systems (MEMS)

The goal of this program is to develop a conformal, charge-dissipating, anti-stiction coating for Micro-Electromechanical Systems (MEMS) devices that are prone to failure if adjacent structures touch and stick or if static charges are not quickly dissipated away from the surface. Self-assembled monolayer (SAM) coatings are ideal candidates because their surface-limited deposition avoids the accumulation of mechanically interfering mass. Vapor-phase processing is a requirement for generating coverage even on surfaces that are non-line-of-sight. Additional complexity in coating design for this application is selecting a composition that simultaneously dissipates charge and prevents stiction. These are two requirements that generally trade off each other.SAM coatings have been shown to reduce stiction-related failures for MEMS devices during fabrication and in operation. Although industry has incorporated this technology into commercial products, such as accelerometers and gyroscopes, the requirements for strategic sensors necessitates special design considerations. These include very long stability in (well-controlled) storage and robustness through strategic radiation environments, which involve parasitic charges that must quickly dissipate to the grounded substrate to avoid erroneous signals.In Phase I, Triton Systems demonstrated a SAM coating that meets the hybrid structure needed for simultaneous charge dissipation and anti-stiction performance. Thermal stability was excellent, indicating strong attachment and stable chemistry. The chemistry is such that functionalization should preferentially coat silicon surfaces and self-limit to a monolayer. Triton’s Phase II effort will include experiments to optimize the SAM coating and improve understanding of its interfacial properties. A successful Phase II program will feature the transfer of Triton’s SAM coating to the vapor phase using standard MEMS foundry capabilities for speedy transition of the validated technology to Production.