Goals:

Develop an EAM potential for Ta from an ab inito force database for use in molecular dynamics simulation of thin film growth.

Introduction: 

Tantalum can be used as barrier layer and adhesion layer in semiconductor
devices. In copper metallization, in order to simulate copper film growth, we need to know the jump rates of atoms both for copper and tantalum atoms. Jump rates can be calculated once we have the values of the activation energy. To calculate the activation energy accurately, we must have a relaible potential available.  However, at present, the analytical form of the EAM Tantalum potential does not predict tantalum properties well. For example, the predicted bulk modulus is 1.35GPa, which is more than 30% smaller than standard value (1.94GPa).

Participants:

Methods: 

We use the Force Matching Method to fit our tantalum potential to a large database of force data from DFT calculations for a variety of structures including liquids, surfaces, clusters, stacking-faults as well as bulk crystal structures.  At the same time, we fit the potential to experimental values such as the lattice constant, bulk modulus, vacancy formation energy, elastic constants, etc.  Using multi-dimensional optimization, we can develop an EAM potential that produces forces that match DFT forces and predicts materials properties that match experimental values.

Results, Publications, and Presentations:  

Our new EAM potential repository is in development.  See a perliminary version here!  

Acknowledgements (funding and computational resources):