Comparison of composition of ultra-thin silicon oxynitride layers' fabricated by PECVD and ultrashallow rf plasma ion implantation

In this paper differences in chemical composition of ultra-thin silicon oxynitride layers fabricated in planar rf plasma reactor are studied. The ultra-thin dielectric layers were obtained in the same reactor by two different methods: ultrashallow nitrogen implantation followed by plasma oxidation and plasma enhanced chemical vapour deposition (PECVD). Chemical composition of silicon oxynitride layers was investigated by means of X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The spectroscopic ellipsometry was used to determine both the thickness and refractive index of the obtained layers. The XPS measurements show considerable differences between the composition of the fabricated layers using each of the above mentioned methods. The SIMS analysis confirms XPS results and indicates differences in nitrogen distribution

The influence of annealing (900?C) of ultra-thin PECVD silicon oxynitride layers

This work reports on changes in the properties of ultra-thin PECVD silicon oxynitride layers after high- temperature treatment. Possible changes in the structure, composition and electrophysical properties were investigated by means of spectroscopic ellipsometry, XPS, SIMS and electrical characterization methods (C-V, I-V and charge- pumping). The XPS measurements show that SiOxNy is the dominant phase in the ultra-thin layer and high-temperature annealing results in further increase of the oxynitride phase up to 70% of the whole layer. Despite comparable thickness, SIMS measurement indicates a densification of the annealed layer, because sputtering time is increased. It suggests complex changes of physical and chemical properties of the investigated layers taking place during high-temperature annealing. The C-V curves of annealed layers exhibit less frequency dispersion, their leakage and charge-pumping currents are lower when compared to those of as-deposited layers, proving improvement in the gate structure trapping properties due to the annealing process