Date of Award

5-2014

Degree Name

MS in Engineering - Materials Engineering

Department

Materials Engineering

Advisor

Richard Savage

Abstract

A process for micromachining of micro-mirror devices from silicon-on-insulator wafers was proposed and implemented. Test methods and force applicators for these devices were developed. Following successful fabrication of these devices, a novel process for fabrication of devices out of the plane of the silicon wafer was proposed, so that the devices could be actuated electrostatically. In particular, the process makes use of thick photoresist layers as a sacrificial mold into which an amorphous nickel-phosphorous alloy may be deposited. Ideal design of the electrostatically actuated micro-mirrors was investigated, and a final design was selected and modeled using FEA software, which found that serpentine-hinged devices require approximately 33% of the actuation force of their straight-beamed counterparts. An aqueous electroless plating solution composed of nickel acetate, sodium hypophosphite, citric acid, ammonium acetate, and Triton X-100 in was developed for use with the process, and bath operating parameters of 85°C and 4.5 pH were determined. However, this electroless solution failed to deposit in the presence of the photoresist. Several mechanisms proposed for deposition failure included leaching of organic solvents from the photoresist, oxidation of the nickel-titanium seed layer on which the deposition was intended to occur, and nonlinear diffusion of dissolved oxygen in the solution.

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