Synthesis and characterization of plasma assisted chemically vapor deposited tantalum

This study focuses on the synthesis of tantalum (Ta) coatings on high strength steel by plasma assisted chemical vapor deposition using tantalum pentachloride (TaCl5) as a preferred precursor and hydrogen (H2) as a reducing agent. The interrelationships governing the growth kinetics, compositions, and coating properties are discussed as a function of deposition temperature, total pressure, and gas composition. The synthesized tantalum coatings are shown to be essentially pure with trace amounts of oxygen, carbon, and chlorine. The coatings are found to be dense and to exhibit conformal coverage. Preferential formation of the α-Ta phase is noted to occur when coatings are grown sequentially and in-situ on a TaNx seed layer.