The objective of the proposed research is to develop chemistry and techniques for the application of hydrophobic coatings onto polysilicon based MEMS structures from aqueous media. The chemical system would consist of two micelle-forming components, a water-soluble silane and a surfactant, dissolved in an aqueous solution. By using pH as a master variable, the attachment of silane micelles as a monolayer would be effected. Using Monte Carlo simulations, the effect of the chemical structure of the surfactant and silane on the attachment will be analyzed and optimal conditions for attachment will be explored. The applied coatings will be tested for various characteristics such as hydrophobicity, orientation, and stability. The metric for the success of the proposed research program is the identification of conditions required for the formation of thermally stable, highly hydrophobic (water contact angles of greater than 120) coatings which, when applied to polysilicon surfaces, are capable of preventing drying and in-use stiction.
The Sensor Products Division of Motorola located in Phoenix is the industrial (GOALI) partner in this research program. Motorola will facilitate testing of the developed coatings in micromachined structures such as cantilever beam arrays and in products such as accelerometers. The industrial partner will assess the compatibility of the chemicals used and processes developed in the research program with commercial fabrication environments.
It is anticipated that the proposed research program with Motorola as the industrial partner, will provide an excellent opportunity for the principal investigator, his students and collaborators to contribute to scientific knowledge and solutions to a problem of great importance to industries involved in the manufacture of MEMS structures. The students involved in the project will gain knowledge in the area of applied surface chemistry, coatings and Monte Carlo simulations and will be able to apply this knowledge to an important industrial problem. Additionally, the interaction with the industry will present the students a very valuable opportunity to learn about the different facets of an industrial process. ***
