PECVD based silicon oxynitride thin films for nano photonic on chip interconnects applications

Thin silicon oxynitride (SiO(x)N(y)) films were deposited by low temperature (~300°C) plasma enhanced chemical vapour deposition (PECVD), using SiH(4), N(2)O, NH(3) precursor of the flow rate 25, 100, 30 sccm and subjected to the post deposition annealing (PDA) treatment at 400°C and 600°C for nano optical/photonics on chip interconnects applications. AFM result reveals the variation of roughness from 60.9 Å to 23.4 Å after PDA treatment with respect to the as-deposited films, favourable surface topography for integrated waveguide applications. A model of decrease in island height with the effect of PDA treatment is proposed in support of AFM results. Raman spectroscopy and FTIR measurements are performed in order to define the change in crystallite and chemical bonding of as-deposited as well as PDA treated samples. These outcomes endorsed to the densification of SiO(x)N(y) thin films, due to decrease in Si-N and Si-O bonds strain, as well the O-H, N-H bonds with in oxynitride network. The increase in refractive index and PL intensity of as deposited SiO(x)N(y) thin films to the PDA treated films at 400°C and 600°C are observed. The significant shift of PL spectra peak positions indicate the change in cluster size as the result of PDA treatment, which influence the optical properties of thin films. It might be due to out diffusion of hydrogen containing species from silicon oxynitride films after PDA treatment. In this way, the structural and optical, feasibility of SiO(x)N(y) films are demonstrated in order to obtain high quality thin films for nano optical/photonics on chip interconnects applications.