Structural and electrical properties of Ta 2 O 5 thin films prepared by photo-induced CVD

Abstract

Tantalum oxide (Ta 2 O 5 ) films and Al/Ta 2 O 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 2 O 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 2 O 5 /Si MOS capacitors. Results show that the Ta 2 O 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 2 O 5 phase. The dielectric constant and leakage current density of the Ta 2 O 5 thin films increase with increasing powers of the UV- lamps. Effects of UV- lamp powers on the structural and electrical properties were discussed.