Integrated model for chemically enhanced physical vapor deposition of tantalum nitride-based films

A zero-order semiempirical model has been developed for chemically enhanced physical vapor deposition (CEPVD), a recently developed hybrid approach to film deposition offering the step coverage of chemical vapor deposition while maintaining film quality similar to films produced by ionized physical vapor deposition (IPVD). CEPVD is done by introducing a chemical precursor to the substrate during IPVD. A synergistic effect between the two processes results in which the high energy ions from IPVD aid in the decomposition of the precursor. The precursor then provides film deposition on surfaces that are not easily impacted by IPVD's directional ions. The model stems from knowledge of reactive sputtering and plasma-enhanced chemical-vapor deposition processes as well as results acquired from CEPVD experiment. It focuses on the Ta-N material system since TaTaN is widely used as a diffusion barrier in Cu damascene processing. Processing parameters are correlated with the target and film surface coverage by Ta, TaN, and organic sites, from which one can predict the operation mode, either metallic or poison, and the film elemental composition. The organic by-products accounting for the detection of carbon on the substrate by Auger electron spectroscopy analysis and poisoning of the target during the processing are categorized into nonvolatile products (OR1) and volatile products (OR2) in a lump-sum assumption. Electron impact, H reduction and ion bombardment are considered as the enhancing mechanisms between the physical and chemical components and included as the reactants of the chemical reactions. Simulation results compare favorably with the experimental data.