Characterization of silicon carbon nitride thin films synthesised by continuous micro-wave plasma assisted chemical vapour deposition

Résumé

Crystalline silicon carbon nitrite thin films have been synthesized by continuous MPACVD in N₂/CH₄ gas mixture on silicon substrates. Prior deposition, discharges stabilisations have been studied and then the plasma is analysed in-situ by optical emission spectroscopy according to experimental parameters (microwave power, gas mixture, pressure and flow rate). Several techniques have been used to characterize the films. Morphological analyses realized by SEM, TEM and AFM show that the films are nano-crystalline and their roughness is around 5 nm. The XRD spectrum and selected area electron diffraction patterns exhibit a signature that correspond to beta-C₃N₄ and SiCN. EDXS and XPS analyses show the presence of C, N, Si and O. The C1s, N1s and Si2p levels obtained from XPS confirm the presence of C-N, Si-C and Si-N covalent bonds typical for SiCN and CN_x films. The presence of Si is justified by the participation of the substrate to the growth by etching. The oxygen comes from the exposure of the films to atmosphere after deposition. The surface was not cleaned by argon bombardment to avoid a structural and bonding modification of the film.