Dielectric properties of Ta2O5 films grown on silicon substrates plasma nitrided in N2O

C-V characteristics and leakage currents of metal-insulator-silicon structures containing insulating film composed of thermally grown Ta2O5 and ultrathin SiOxNy layer grown in N2O plasma were studied. Leakage in the structures is explained by tunneling in SiOxNy layer and Poole-Frenkel internal field assisted emission in Ta2O5. Theoretical calculations were made by known theoretical expression, while using fitted values of the thickness of SiOxNy, defect related constants for Ta2O5, and compensation degree r=1 for Ta2O5. For positive gate biases, tunneling of electrons from the silicon conduction band through SiO2 is considered, while for gates negatively biased, tunneling of holes from the silicon valence band. In the early stage of nitridation barriers for injection decreases rapidly, then much slower. The thickness of the SiOxNy layer increases slowly with the nitridation time, as a result of the created barrier against diffusion of silicon atoms created by nitrogen incorporated at the interface between the silicon and oxide SiOxNy layer. (orig.)