Photo-induced CVD of tantalum pentoxide dielectric films using an injection liquid source

In this paper the new technique of ultraviolet-assisted injection liquid source (UVILS) chemical vapour deposition (CVD) of thin tantalum pentoxide films on p-type Si (100) wafers is presented. This method involves the use of a krypton chloride (KrCl^*) excimer lamp, radiating at 222 nm, and a novel injection liquid source capable of delivering precisely controllable quantities of a novel high-volatility liquid metalorganic precursor into the CVD chamber. The physical and chemical properties of the films formed have been studied using spectroscopic ellipsometry and Fourier transform infrared spectroscopy measurements while the electrical properties of the films were determined by surface charge analysis, capacitance-voltage, and current-voltage measurements. Simple metal/oxide/silicon capacitor structures incorporating this tantalum pentoxide have been fabricated. Refractive index values of 2.09±0.07, dielectric constant values of 18-24, fixed oxide charge content of < 1 × 10¹¹ cm^-2 and breakdown fields higher than 2 MV/cm can be readily obtained in the as-deposited films.