Structural and electrical properties of Ta_2O_5 thin films prepared by photo-induced CVD

摘要

Tantalum oxide (Ta_2O_5) films and Al/Ta_2O_5/Si MOS capacitors were prepared at various powers by ultraviolet photo-inducing hot filament chemical vapour deposition (HFCVD). Effects of ultraviolet light powers on the structure and electrical properties of Ta_2O_5 thin films were studied using X-ray diffraction (XRD) and atomic force microscopy (AFM). The dielectric constant, leakage current density and breakdown electric field of the samples were studied by the capacitance-voltage (C-V) and current-voltage (I-V) measurements of the Al/Ta_2O_5/Si MOS capacitors. Results show that the Ta_2O_5 thin films grown without inducement of UV light belong to amorphous phase, whereas the samples grown with inducement of UV-light belong to δ-Ta_2O_5 phase. The dielectric constant and leakage current density of the Ta_2O_5 thin films increase with increasing powers of the UV- lamps. Effects of L" V-lamp powers on the structural and electrical properties were discussed.