Abstract
Recent development of opto-electronic and communication products, computer peripheral equipment, bio-medical devices, has resulted in increasing demands for metallic nano/micro structures. Nanoimprint is considered as one of the most potential processes for manufacturing nanostructures that have characteristic size less than 100 nm. Different from currently prevailing hot-embossing nanoimprint processes that imprint patterns on photo-resist materials and then employ lithography, this thesis proposes a method that directly transfers patterns on metallic thin films. To the best of our knowledge, there is no similar research on the formation mechanism of our proposed nanoimprint process, so the mechanics and length-scale effect must be investigated. This study utilizes molecular dynamics to simulate the nanoimprint process and to study the length-scale effect by varying the pattern width of the mold and the thickness of the thin film. In addition, the strength, hardness, substrate effect, hydrostatic zone, plastic deformation, etc., are analyzed on the basis of fundamental theories of material and mechanics. Moreover, an experimental study is also performed, which includes preparation of metallic thin film, characterization of material properties by nano-indentation, fabrication of molds by e-beam lithography as well as photo lithography, pattern formation by imprinting, and measurement of surface topology by SEM, FESEM and AFM. In consistence with the trend obtained from molecular dynamic simulation, experimental results further demonstrate that the length-scale effect is one of the important factors governing the quality of formation. Finally, a parametric study is conducted by both simulation and experiment; the results can provide useful information for the design of the mold and imprinting process.