Method and apparatus for depositing tantalum-based thin films with organmetallic precursor

Abstract

A method and apparatus are disclosed for depositing a tantalum-containing diffusion barrier, such as a TaN barrier layer, by dissolving a tantalum-bearing organometallic precursor, such as PEMAT or PDEAT, in an inert, low viscosity, high molecular weight, low volatility solvent, such as octane, heptane, decane or toluene. The precursor-solvent solution is vaporized and flowed over a substrate to deposit the barrier. The precursor solution has a viscosity substantially similar to that of the solvent by maintaining the ratio of precursor to solvent at a generally low value, such as approximately 10% precursor. The boiling point of the solvent is substantially similar to the boiling point of the precursor, such as within 50% of the precursor boiling point at one atmosphere, to enhance repeatability of barrier film quality. Resistivity of the barrier film is reduced by flowing a reactive gas with the precursor flow, the reactive gas reducing the carbon content of the barrier film, or by co-deposition of a resistivity-lowering metallic dopant with the precursor solution. Alternatively, resistivity is reduced by controlling the nitrogen content of the film by a post-deposition plasma treatment of the barrier with a reducing gas.