Structural and Electrical Characterizations of Yttrium Oxide Films after Postannealing Treatments

We investigated annealing effects on yttrium oxide films elaborated at by pulsed injection plasma-enhanced metallorganic chemical vapor deposition. A certain amount of carbon is present in the as-deposited layers due to incomplete metallorganic precursor decomposition. Because the carbon is known to be disadvantageous for the dielectric permittivity, several annealing post-treatments (under Ar or at and under at during at atmospheric pressure) were performed. Chemical modifications in the yttrium oxide layer and also at the interface were investigated combining several analyses [as infrared spectroscopy, (angle-resolved) X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron microscopy, electron energy loss spectroscopy, and Rutherford backscattering spectrometry] carried out on thick and thin films (respectively, and ). High-temperature post-treatments result in a significant reduction of carbon content. However, the presence of oxygen at high temperature (even for low residual oxygen partial pressure) involves formation at the interface and leads to the transformation of the yttrium oxide into Y-based silicates, which, for the thin films, results in the absence of crystalline phase. The anneal does not modify the film's chemical nature except for a significant reduction of hydrogen content. After annealing under , a strong improvement of the capacitance behavior is observed, especially on the thin films.