| At present, the limits of conventional planar photolithography have been tested and stretched in many different ways. Applications in different fields, such as MicroElectroMechanical System (MEMS), micro-fluidics and photonic crystals (PhCs), demand the extension of conventional planar lithography to full three-dimensions (3D). At the same time, it has become increasingly more difficult for photolithography to meet the requirements of the rapidly increasing integration level, owing to fundamental wavelength limitation. In this research effort, I present two unique solutions, namely 3D multi-layer photolithography and Chemical lithography (ChemLith) to overcome these limitations.; The 3D multi-layer photolithography approach is based on conventional planar photolithography technology, and leverages well-developed materials, facilities and knowledge. However, two critical modifications, 3D confined exposure and multi-layer resist deposition have been made to planar photolithography in order to give it extra dimensionality. Accordingly, I compare different exposure confinement methods, study parameters that affect exposure penetration depth, explore problems associated with multi-layer resist deposition and discuss how spin-thickness and uniformity are affected and engineered. Potentially usable in many applications because it can make arbitrary 3D structures, the 3D multi-layer photolithography has been demonstrated in this work for the fabrication of 3D PhCs and micro-fluidic system.; I also propose chemical lithography (ChemLith), which is based on the polymerization of resist molecules using an external acid source for patterning nano-scale planar structures. Different acids and resist systems have been initially tested for this concept. Both a parallel replication process that employs a pre-fabricated template and a serial prototype process that uses a nano-probe have been developed. I discuss solutions for many practical issues, and explore the possibility of using an external electric field to facilitate the acid/proton diffusion process. Preliminary results with sub-100nm feature size are presented to show the promise of ChemLith as a next-generation lithography (NGL) candidate.; The processes developed in this work will not only extend the capability of the current photolithography technology, but will also immediately provide crucial solutions for fabrication in nano-photonics and micro-fluidics. As enabling tools, these lithography processes will have long term effect on many other applications. |
