Development of Nanoimprint Lithography for Applications in Electronics, Photonics and Life-sciences
Abstract: This thesis describes different aspects of nanotechnology manufacturing with nanoimprint lithography (NIL), a relatively new nanofabrication tool capable of high resolution and high throughput. Surface structure creation with NIL is based on mechanical deformation of the patterning material. This is radically different from the two main established methods, ultra violet lithography (UVL) and electron beam lithography (EBL), which rely on chemical modification of the patterning media. The thesis is divided into two main parts, the first of which discusses process related issues and the second describes applications. Thus the initial discussion concerns production of stamps, perhaps the most important part of a working imprint technology. Aspects such as choice of materials, patterning methods, implications of structure layout and anti-sticking that have been used or developed in my work are described. The chapter on process outlines details concerning imprint related issues for different substrate materials and polymers and how these impact imprint parameters. The chapters on applications give a short introduction to each of them, and cover life-science, sensors, electronic devices and material research. However, the emphasis is on imprint related issues of the work, since this was my part of the projects. In the biological applications it is shown that nanoimprint patterned polymers are biocompatible and can be used to guide axon growth or create directional movement of motor proteins. In the following chapter imprint and a lift-off process is used to make interdigitated array electrodes for electrochemistry and cantilever sensors. It is shown that NIL can pattern both large area structures (contact pads) and nanometer structures in one single-step process. The electronic devices are made in III-V material and imprint is used to create an etch mask for a wet etch process. We show that the imprinted structures have properties similar to those made by EBL and thus that the electronic properties are not affected by the high pressure and temperature of the imprint process. In the last chapter we show using nanoimprint and a lift-off process that imprint can be used to position metal particles on a surface, which in turn may function as catalytic particles for growing nanowires.
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