Date of Award

Summer 2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Micro and Nanoscale Systems

First Advisor

Cheng Luo

Abstract

Metals have been widely used in the areas of integration circuit (IC) and microelectromechanical systems (MEMS) fields as materials for gates, contact pads, interconnects, corrosion resistance coatings, rectifying contacts, redundancy memories, heating elements, mechanical parts, magnetic component, etc. due to their good properties, such as high electrical conductivity and good thermal conductivity. Conducting polymers, because of their promising potential to replace silicon and metals in building devices, have attracted great attention in recent decades.

Traditional photolithography methods are often used to pattern metals and conducting polymers. However, it cannot be used to fabricate nano patterns because the minimum feature size is limited by wavelength of light. Lithography processes also involve aggressive chemicals, organic solvents, light, or moisture, and thus may affect human health, pollute the environment, and degrade devices. Therefore, a new pattern technique is needed to solve these problems. Soft lithography has been successfully used to fabricate both metal and conducting polymer patterns. The techniques are free of harmful radiations and other chemicals that might alter the properties of the conducting polymer. However, the problems which result from a soft stamp may cause dislocations of patterns or variations of dimensions. The hot embossing process has low cost, high throughout, and high reliability. Also, no chemical etchant or light is involved in this process. On the other hand, it cannot be directly used to pattern metal or conducting polymer.

Motivated by a macrocutting process often used in the manufacturing industry to pattern sheet metals, an innovative intermediate-layer lithography (ILL) approach is developed in this work to generate micro/nano patterns in a thin metal or conducting polymer film. In the ILL method, an intermediate layer of PMMA is introduced between a silicon substrate and a thin metal or conducting polymer film. Subsequently, the metal or conducting polymer film is imprinted through a mold insertion using a hot embossing technique. The ILL has been applied to produce various micropatterns in Al, PEDOT, and PPy films. Micro devices, such as heaters, diodes and capacitors, were also fabricated using the ILL method. Metal nanopatterns have been successfully generated using this approach. This dissertation addresses the corresponding fabrication details and gives a numerical interpretation of some interesting experimental phenomena observed.

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