Nanolithography using Sequential Infiltration Synthesis Involving Undergraduate Students at Illinois State University

With the rise in emerging technologies in the field of microelectronics, optoelectronics, sensing, and bioengineering exploring different patterning processes for inorganic nanomaterial patterns became imperative. Sequential infiltration synthesis (SIS) a vapor phase inorganic material deposition method has been established recently to make inorganic nanopatterns using a polymer as a template. SIS enables the control of localized inorganic material growth in the targeted domains of polymers (such as in block copolymers). The effectiveness of the SIS process for advanced nanopatterning has been demonstrated for oxide materials such as aluminum and titanium oxides. In this work, we have fabricated aluminum oxide (Al₂O₃) nanoparticles using SIS in two different polymers and removed the polymers with oxygen plasma etching (referred to as nanolithography). We have used nanoparticles of polymethylmethacrylate (PMMA) and polycaprolactone (PCL) polymers, which contain active functional groups carbonyl (C=O) to interact with SIS metallic precursor trimethylaluminum (TMA). We have previously shown using in-situ Fourier Transform Infrared Spectroscopy (FTIR) that  PCL thin film has strong interaction with TMA and far more compared to PMMA thin film. In this work, we have performed a comparative study on the amount of infiltration in nanoparticles of these polymers and studied the effect on nanoparticles size after nanolithography using scanning electron microscopy.