Browsing by Subject "nanoimprint"
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Item Development of Advanced Nanomanufacturing: 3D Integration and High Speed Directed Self-assembly(2011-10-21) Li, HuifengDevelopment of nanoscience and nanotechnology requires rapid and robust nanomanufacturing processes to produce nanoscale materials, structures and devices. The dissertation aims to contribute to two major challenging and attractive topics in nanomanufacturing. Firstly, this research develops fabrication techniques for three dimensional (3D) structures and integrates them into functional devices and systems. Secondly, a novel process is proposed and studied for rapid and efficient manipulation of nanomaterials using a directed self-assembly process. The study begins with the development of nanoimprint lithography for nanopatterning and fabrication of 3D multilayer polymeric structures in the micro- and nano-scale, by optimizing the layer-transfer and transfer-bonding techniques. These techniques allow the integration of microfluidic and photonic systems in a single chip for achieving ultracompact lab-on-a-chip concept. To exemplify the integration capability, a monolithic fluorescence detection system is proposed and the approaches to design and fabricate the components, such as a tunable optical filter and optical antennas are addressed. The nanoimprint lithography can also be employed to prepare nanopatterned polymer structures as a template to guide the self-assembly process of nanomaterials, such as single-walled carbon nanotubes (SWNTs). By introducing the surface functionalization, electric field and ultrasonic agitation into the process, we develop a rapid and robust approach for effective placement and alignment of SWNTs. These nanomanufacturing processes are successfully developed and will provide a pathway to the full realization of the lab-on-a-chip concept and significantly contribute to the applications of nanomaterials.Item High Resolution Nanoimprint for Nanophotonics(2014-04-28) Jiang, YouweiNanophotonics have drawn huge attention in recent years in various applications. Surface sensing technique, including surface-enhanced Raman spectroscopy (SERS), is an important topic of nanophotonics and has been widely investigated. The capability of SERS-active device depends on two main factors: good reproducibility and high enhancement factor. Ordered metallic nanostructures with high resolution are usually preferred for SERS application. Nanoimprint lithography can provide a low-cost and high resolution fabrication technique for SERS-active devices. The objective of this research is to explore the application of nanoimprint lithography in SERS-active devices. This work begins with two issues of nanoimprint lithography: mold fabrication and throughput improvement. The potential of nanoimprint lithography depends on reliable mold fabrication. Two techniques are investigated, which are polyelectrolyte electrostatic self-assembly and controlled polymer reflow. Based on the observation of exceptional thermal stability of entangled polymer, step-and-repeat thermal nanoimprint lithography is developed. This technique significantly improves the throughput and enables the large scale application of thermal nanoimprint. Ordered metallic nanostructures have been widely used as SERS-active substrates. In order to achieve high enhancement, extremely high resolution is needed, which can be limited by lithography technique. In this work, SERS-active devices based on gap surface plasmon polaritons are fabricated by nanoimprint lithography. 17 times more enhancement is achieved compared with conventional SERS-active devices on the same structure dimensions. This technique opens up possibilities of single molecule detection in the future.Item Stability of Self-Assembled Monolayer Surfactant Coating in Thermal Nanoimprint(2012-02-14) Lunsford, PatrickHigh-resolution and low-cost fabrication techniques are essential for nanotechnology to overcome the commercialization barrier to benefit our society. Since its inception nanoimprint has become the ideal technology to fabricate dense sub-micron structures over large areas with low cost, which are important to many applications such as high-density storage disks and diffractive optical devices. The decade-long development in nanoimprint equipment has reached a point where large-scale manufacturing of high-density nanostructures are possible. However, there are a few remaining issues that need to be studied before the advent of commercial application of nanoimprint. In this work we look at a pressing issue, long-term stability of the mold surfactant coating. It is important to understand the details of the surfactant wear during nanoimprint in order to limit defect density to a tolerable threshold in a high-volume manufacturing process. To study this we went through a nanoimprinting procedure and measured chemical and physical alterations in the coating. The surfactant wear information also helps to optimize the time interval for surfactant recoating to keep the fabrication throughput as high as possible. In this paper we characterize the stability of two commonly used surfactants as well as prescribe a new technique for mold anti-adhesion. Through this work we see that FDTS and OTS undergo significant degradation in air and gradual degradation by chain scission is observed during the nanoimprint procedure. It is also noted that an embedded anti-adhesion layer is effective for mold releasing.