Abstract
This research proposes a technique called insertion nanoimprint, which features transferring the metallic (in this thesis, we used Al/Cu) wire gratings fabricated on a silicon wafer into a dielectric (in this thesis, we used PMMA (PolyMethyl MethAcrylate)) substrate under appropriate temperature and pressure conditions. It is also an innovative process that integrates the reversal nanoimprint with conventional nanoimprint process, including transferring metallic structures and defining pattern, respectively. The proposed insertion nanoimprint possesses the advantages of being able to transfer stable metallic wire gratings directly into a polymeric substrate and offer flatly finished surface for subsequent processes, such as sealing and packaging. Furthermore, this technique can avoid the embedded nanostructure from damage due to contamination and stresses during packaging or transportation. In addition, we proposed an efficient process to fabricate insertion structure, with which features manufacturing insertion structure inside PMMA substrate through only three steps, including nanoimprint, metal deposition and CMP process. Therefore, this proposed technique can construct a stable insertion structure continuously and simply for mass production. As the pitch of metallic wire gratings of insertion structure reduces to less than a half of the wavelength of incident light, it offers polarizing function and can be used as a polarizer. To achieve high polarization, it must possess Al wire gratings of insertion structure with high aspect ratio. Insertion structure can be the solution with cross stacking structure as fabricating high aspect ratio Al wire gratings for avoiding alignment in stacking process. Besides, we proposed a bi-layered structure, which consists of an Al layer on the top and a PMMA layer at the bottom, to enhance the optical performance, such as extinction ratio, through extending the O2 plasma etching time. Moreover, we fabricated an insertion structure with Cu wire grid inside PMMA substrate. After optical and electrical measurement, we demonstrate that this proposed structure has potential for being applied to transparent metal electrode. Keywords： Insertion nanoimprint, insertion structure, bi-layered structure, transparent metal electrode, metallic wire gratings, polarizer, flexible substrate, cross stacking structure