Silicon Dioxide Deposition in Polymer Using Sequential Infiltration Synthesis—In Situ FTIR Study

Silicon dioxide (SiO₂) is one of the most abundant and well-studied materials in the world of semiconductor materials because of its electrical resistivity, stability against oxidation, and moisture resistivity. 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 lithography processes such as e-beam lithography and optical lithography which are expensive methods and are showing limitations in sub-20 nm level. 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. Sequential infiltration synthesis (SIS) is a two-step gas-phase molecular assembly reaction involving the desired inorganic material precursors inside an Atomic Layer Deposition (ALD) chamber. SIS 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 in the mass production of organized nanoscale materials with controlled material properties. A better understanding of the SiO₂ growth mechanism and interaction of SiO₂ precursors with different polymers using in-situ FTIR will open up new avenues for nanopatterning this material for many low-dimensional dielectric-based and high temperature-based applications.