Molecular dynamics simulation of sputter trench-filling morphology in damascene process

Abstract

This article presents the use of molecular dynamics ͑MD͒ simulation to investigate the influence of process parameters on sputter trench-filling morphologies in the damascene process. We focus not only upon the mechanisms of trench-filling formation, but also upon the coverage percentage at various transient states during the deposition process. The MD simulation includes a three-dimensional trench model and a deposition model, and uses the many-body, tight-binding potential method to represent the interatomic force acting between atoms. The results of the study indicate that an ideal trench-filling morphology, i.e., one in which the trench is completely filled, with no trapped voids, is most likely to occur as the incident energy of the deposited atom increases, and for higher substrate temperatures. It is found that the principal influence of an increased incident energy is to improve the migration ability of deposited atoms, particularly along the two sidewalls of the trench. This is beneficial since it alleviates the self-shadowing effect, thereby improving coverage of the trench bottom by deposited atoms, particularly in the corners. An increased substrate temperature is influential in improving the fluidity of the atoms deposited within the trench. This promotes the filling of the voids which tend to form at the intermediate stage of the deposition process. Finally, it is found that of the two process parameters investigated in this study, the filling pattern of the trench is most strongly influenced by the incident energy of the deposited atoms.

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