Selective synthesis and characterization of HYSYCVD-Si<inf>2</inf>N<inf>2</inf>O

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: Si8.00N8.00O4.00; 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: SiCp/Sip 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. © 2008 Elsevier B.V. All rights reserved.