Selective synthesis and characterization of HYSYCVD-Si2N2O

In this work, stoichiometric silicon oxynitride (Si₂N₂O) has been successfully synthesized using a selective approach via hybrid precursor system-chemical vapor deposition (HYSYCVD). The deposited oxynitride phase has the following structural parameters: formula sum: Si_8.00N_8.00O_4.00; formula mass: 400.7352 g mol^-1; density: 2.8010 g cm^-3; orthorhombic structure with lattice parameters (Å): a = 8.898, b = 5.495, c = 4.858. The optimum conditions for maximizing the amount of Si₂N₂O are as follows: SiC_p/Si_p substrate with 60% porosity, UHP-N₂ at a flow rate of 10 cm³ min^-1, and no use of diluent. According to ANOVA, flow rate of nitrogen precursor is the processing parameter that most significantly affects Si₂N₂O formation, with a relative contribution of 46%, followed by the type of nitrogen precursor (44%). Regarding the best nitrogen precursor, thermodynamic predictions on the formation of Si₂N₂O are in good agreement with ANOVA results. Analysis by SEM shows that Si₂N₂O is deposited into the preforms as rough fibers, snow-like fibers and spheres.