Effect on silicon nitride thin films properties at various pressure of R.F. magnetron sputtering

Abstract

Silicon nitride is a well-known kind of material with numerous applications such as gate dielectrics and etch-masks in semiconductor device fabrication, anti reflective coatings in solar panel manufacturing and optical waveguides in biosensing fields. In this work, Silicon nitride thin films were prepared using radio frequency (R.F.) magnetron sputtering technique at room temperature. The properties of thin films were investigated with respect to sputtering-gas pressure during film deposition. The produced thin films were characterized with spectral reflectance, AFM, FTIR and FE-SEM techniques for growth rate and optical properties, surface roughness and morphology, chemical bonding information and surface micro structures respectively. Spectral reflectance results showed that there existed an optimum value of sputtering-gas pressure for increase in growth rate and beyond that value the growth rate started decreasing. Refractive index was found to increase with increased pressure confirmed the films were Si-rich. AFM results revealed the increment in surface roughness is in direct proportion with working pressure. FTIR results showed the overlapping of Si-N and Si-O characteristic bands and its shift toward higher wave number due to increasing Si content in deposited films. FE-SEM results showed prominent changes in surface micro structure with higher sputtering-gas pressures.