Molecular dynamics simulation of stress induced by energetic particle bombardment in Mo thin films

Molecular dynamics (MD) simulations are performed to analyze the evolution of defects and stress caused by low energy (25-400 eV) Ar bombardment of polycrystalline Mo thin films. Simulations were performed under different conditions to explore the role of grain boundaries (GBs), Ar-atom's kinetic energies, and incident directions on defect generation. The results show that the GBs enhance the production of interstitial defects, producing compressive stress at much larger depths than the implantation range. This is attributed to sequences of atomic collisions that knock atoms into GBs instead of a diffusional process. Decreasing the grain size or increasing the kinetic energy of the incoming particles increases the number of interstitials in the film, which increases the compressive stress. The incident angle has little influence on the number of interstitials in the film, but the sputtering yield depends on the polar angle. The stress distribution can be modeled by a superposition of the different defect distributions with the appropriate relaxation volumes.

Automated summary

The study used molecular dynamics simulations to analyze the defects and stress in polycrystalline Mo thin films caused by low energy Ar bombardment. It was found that grain boundaries enhance the production of interstitial defects, leading to compressive stress at much larger depths than the implantation range. Varying the grain size and kinetic energy of incoming particles affects the number of interstitials in the film, subsequently impacting the compressive stress.