Sequential Infiltration Synthesis of Silicon Dioxide for Nanopatterning – In Situ FTIR study

Silicon dioxide (SiO₂) is one of the most abundant and well-studied semiconductor materials in because of its electrical resistivity, and stability against oxidation and moisture. With the dimensions of the devices scaling down to sub-100 nanometer, nanopatterns of SiO₂ are becoming crucial for semiconductor device applications and emerging technologies. The majority of the works on SiO₂ nanopatterning for different applications are performed with conventional and expensive lithography processes such as e-beam and optical lithography. In this work, we are presenting SiO₂ material deposition using sequential infiltration method (SIS), a process that has been demonstrated to make inorganic nanopatterns using a polymer as a template. SIS is a two-step gas-phase molecular assembly reaction and enables localized inorganic material growth in the targeted domains of polymers with interactive functional groups. We have used polymethylmethacrylate (PMMA) polymer film for our study. We have performed in-situ Fourier Transform Infrared Spectroscopy (FTIR) study during the half and full cycles of the SIS process inside PMMA to understand the reaction mechanism of the precursor and polymer. The selective infiltration is advantageous for assuring large-scale uniformity of organized nanoscale materials. A better understanding of the SiO₂ growth mechanism using in-situ FTIR will open up new avenues for nanopatterning this material for many low-dimensional dielectric-based applications.