Compositional analysis of silicon oxide/silicon nitride thin films

Hydrogen, amorphous silicon nitride (SiN_x:H abbreviated SiN_x) films were grown on multicrystalline silicon (mc-Si) substrate by plasma enhanced chemical vapour deposition (PECVD) in parallel configuration using NH₃/SiH₄ gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation) in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON) structure. Secondary ion mass spectroscopy (SIMS), Rutherford backscattering spectroscopy (RBS), Auger electron spectroscopy (AES) and energy dispersive X-ray analysis (EDX) were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiN_x. Indeed, oxygen diffused to the nitride layer into Si₂O₂N during dry oxidation.