A novel fabrication technique for three-dimensional nanostructures.

摘要

Three dimensional micro- and nano-structures are commonly used in the field of Photonics, Optoelectronics, Sensors and Biological applications. Although numerous physical models are developed, a major challenge has been in their fabrication which is commonly limited to conventional layer-by-layer techniques. In this dissertation, a novel method for fabricating three dimensional structures using Electron Beam Lithography (EBL) will be presented.;Electron Beam Lithography is one of the most important tools used in the field of micro- and nano-fabrication. Ultra high resolution (< 10 nm), ability to pattern without the use of a mask, versatility and large intrinsic depth of focus are its primary advantages. Large depth of focus provides the capability to pattern thick layers of resist. This feature of EBL coupled with the deposition of multiple layers of resist has led to the ability to fabricate three dimensional structures. A thorough review of EBL, the proposed Multi-Layer Direct Write technique and other issues related to fabrication of three dimensional structures will be presented.;Resists are films sensitive to electromagnetic radiation dispersed in suitable solvents. Currently, resists are deposited on wafers using the process of spin-coating. Consecutive spin coating of resists requires the use of compatible solvents to prevent unwanted dissolution. Hansen Solubility Parameters (HSP) were used to determine compatible solvents and resist polymers were recast into them. Detailed solubility analysis of all commercially available electron beam resists is also presented. Other issues related to depositing multiple layers of resist are also discussed.;Polymeric three dimensional structures exposed to electron beam radiation have limited structural strength and during the process of development, fluid interaction with structures causes deformation. This has been observed in some cases of free standing nanostructures and Finite Element Modeling was employed to determine its bounds. Different models illustrating fluid flow and its interaction with structures will presented and compared to experimental observations.