Effect of stepped Si (001) substrate on Cu thin film growth

Abstract

The growth processes of Cu thin film on stepped Si(001) substrate were investigated using molecular dynamics simulation. The modified embedded atom method was used to describe the atomic interaction between Cu-Cu, Si-Si, and Si-Cu. In this study, four different Si(001) substrate configurations were examined: i) flat Si(001) substrate; ii) stepped Si surface with 3-monoatomic layers step; iii) Stepped Si surface with 5-monoatomic layers step; iiii) stepped surface with 7-monoatomic layers. Our aim here is to investigate the effect of stepped substrate on the structure, the surface roughness, and the morphology of deposited Cu thin film. The results show that the Cu film obtained has a crystalline structure based on the radial distribution function. In addition, the morphology of Cu film is not smooth for the different stepped substrates. More precisely, the surface roughness increases when the substrate presents a step and rises with the augmentation of the step height. On the other hand, our results reveal that the penetration of Cu atoms in the simplest case of the flat configuration is limited to the top layer of the substrate. While for the stepped substrate, our findings show that the penetration in the stepped substrate is more important and deeper within the upper terrace compared to the lower terrace. Furthermore, the numerical calculations demonstrate that the step height has no significant effect on the penetration of Cu atoms on the Si(001) stepped substrate. These results are appropriate for the deposition of copper atoms into the stepped substrate of silicon.