Nanoimprint Lithography (NIL) is becoming a powerful tool for nanolithography, nanofabrication and nanomanufacturing for nanotechnology applications. However, there is still a lack of systematic study of key processing parameters, which determine the imprinted pattern quality in terms of uniformity and replication fidelity.
This research focuses on identifying the most important parameters in a nanoimprint process, in which microscale patterns were imprinted into polymethyl-methacrylate (PMMA) polymer with polydimethylsiloxane (PDMS) mold. The effects of several parameters such as pre-imprint temperature, pre-imprint pressure, imprint temperature, imprint pressure, imprint time, venting temperature and venting time, were varied in a certain range during the imprinting process. The imprinting results were analyzed with a three-level design of experiments (DOE) analysis. It was found that the pre-imprint pressure and imprint temperature are the key parameters. In addition, the DOE analysis is a powerful tool for NIL process optimization.
As a practice, a vacuum assisted and selective coating (VASC) method based on a commerical nanoimprinting tool was developed to fabricate micro-hole arrays on a PbSe nanocrystal film to study its spectral response to IR radiation for applications such as IR detection and photovoltaic. The process optimization significantly improves imprinting quality.