Thin tantalum pentoxide films deposited by photo-induced chemical vapor deposition using an injection liquid source

Abstract.

We report the growth of thin tantalum pentoxide films on Si (100) by ultraviolet-assisted injection liquid source (UVILS) chemical vapor deposition (CVD) at low temperatures (200–350 °C). This new technique combines the intense radiation from an excimer lamp (λ=222 nm) with a novel injection liquid source capable of delivering precisely controllable quantities of a liquid metalorganic precursor into the CVD chamber. The composition and optical properties of the oxides were determined using a variety of standard characterization methods. After optimization of the deposition parameters, the best layers were incorporated into simple MOS test structures to enable electrical characterization. Refractive index values of 2.09±0.07, fixed oxide charge content of <5×10¹⁰ cm^-2, breakdown fields higher than 2 MV/cm and dielectric constant values of 18–24 were readily achievable in the as-deposited films. These properties compare favorably with those for layers prepared by conventional thermal-CVD at significantly higher temperatures of 500 °C.