A comparative molecular dynamics study of copper trench fill properties between Ta and Ti barrier layers

The copper atoms deposition on tantalum diffusion barrier layer in a damascene process was studied using molecular dynamics simulation with the embedded atom method (EAM) as interaction potential for the present alloy metal system which is based on invariance-preserving alloy model. The present results are discussed in terms of void formation, coverage percentage and alloy fraction. The effects of different process parameters on the trench-filling morphologies and microstructures including incident energies of depositing atoms and substrate temperatures were investigated. Comparing with Ti diffusion barrier under the same process parameters, it is found that due to better thermal stability that significant improvement in coverage percentage can be obtained using the tantalum barrier layer, especially at high incident energies and high substrate temperatures.