NEODYNETICS CORPORATION — Department of Defense SBIR Phase I: N231-076

Description

This project provides an opportunity to develop an advanced surface coating technology for fabricating an anti-stiction, self-assembly monolayer (SAM) on silicon wafers for use in micro-electromechanical systems (MEMS). The work will advance the state-of-the-art in SAM fabrication by improving coating uniformity, providing conformal coverage of micron structures, and expanding the SAM molecule selection range, all of which lead to better MEMS stability, reliability, and functionality.  It will also meet the navy requirements by delivering a robust anti-stiction SAM coating with high electrical conductivity along the molecule chain while being non-conductive between molecules (<100Ohm resistance between the coating and silicon substrate and >1MOhm resistance across the coating). However, achieving these binary characteristics is challenging because high electrical conductivity along the linear (hydrophobic) molecular chain can increase cross-molecule conduction. Therefore, we are proposing an advanced SAM fabrication process that combines traditional SAM fabrication with additional steps that provide better control of the monolayer self-assembly process, thereby allowing us to precisely engineer the monolayer structure at the molecular level. We developed and implemented similar SAM technologies in prior work and found them to produce repeatable, uniform, high quality coatings. The process will also be cost-effective and scalable for mass production.   Micro-electromechanical systems (MEMS) fabrication has experienced rapid growth in the past decade due to its versatility and breadth of applications. However, one of the factors limiting its widespread use and reliability is the problem of stiction that may occur during fabrication and detrimentally affect MEMS operations. Stiction arises at the molecular level due to surface forces such as capillary action, hydrogen bonding, electrostatics, and van der Waals effects, which can dominate interactions at the micro-scale. Recently, applications using sub-nanometer SAM films have attracted attention in tackling stiction problems because of their high hydrophobicity, low surface energy, and compact packing structures that can inhibit capillary forces. These applications also provide coatings that exhibit low adhesion and friction, minimal energy loss, conformal coverage, and increased stability within a wide range of environmental conditions.