Raman Analysis of Deposition Pressure Variations in Nanocomposite SiCN Coatings: A 4-Stage Model

Abstract

Polymer-derived ceramic (PDC) based coatings like Si-C-N and their derivatives are gaining importance day by day in N/MEMS and aerospace due to their thermos-mechanical stability and conductivity. The crystallized, amorphous, and near amorphous morphology of SiCN nanocomposite coatings based on deposition conditions requires thorough investigation for appropriate utilization as they lead to differences in mechanical properties (quantified using nanoindentation in this case). A 4-stage model was proposed based on Raman spectroscopy due to the N2-Ar pressure variations during the deposition process of SiCN coatings by magnetron sputtering. The integral intensity of the G (graphitic), disorder (D), and tetrahedral (T) peaks namely IG, ID, and IT were calculated after the deconvolution of the spectra. The sp2 domain size and defect parameters were evaluated and correlated with the hardness and different bond formation involving Si, C, and N. Image analysis revealed the atomic migration involved during the growth process leading to crystallization along with the formation of voids and defects. The observations were supported by FTIR and TEM-SAED analysis. The outcomes provide a foundation causing an urge to develop similar models with further elemental additions and correlate with various physical properties.