Electrical and structural characteristics of yttrium oxide films deposited by rf-magnetron sputtering on n-Si

Yttrium oxide dielectric films were grown by rf-magnetron sputtering on n-Si(100) substrates and annealed in vacuum at temperatures ranging from 400 to 600 degreesC. The main aim of this work was the investigation of the interface between the dielectric film and silicon. Both structural (x-ray diffraction and transmission electron microscopy) and electrical characterization were used for this purpose. No structural change was observed on the interfacial native oxide layer after annealing at 600 degreesC for 1 h. Metal-oxide-semiconductor structures defined by the evaporation of Al electrodes show low leakage currents, moderate dielectric constant (around 14), and high densities of positive charges trapped in the oxide. Hysteresis effects in capacitance-voltage (C-V) curves reduce with the annealing temperature. Another interesting observation is the parallel shift of the C-V curves along the voltage axis with frequency. An insulator trap model is proposed to explain this behavior.