Coalescence kinetics and microstructure evolution of Cu nanoparticles sintering on substrates: a molecular dynamics study

Nano copper sintering technology has great potential to be widely applied in the wide-bandgap semiconductor packaging. In order to investigate the coalescence kinetics of copper nano particles for this application, a molecular dynamic (MD) simulation was carried out at low temperature on a special model containing two substrate and multiple particles in between. Accordingly, thorough microstructure and dislocation investigation was conducted to identify the atomic-scale evolution in the system. The corresponding findings could provide evidence on the new particle-substrate sintering mechanism. Furthermore, atomic trajectories tracking method was applied to study the rotation behavior of different sized nano particles. New rotation behavior and mechanism were described. Additionally, the study on the size effect of copper particles on the sintering process and coalescence mechanism was conducted via comparing the microstructural and dislocation distribution of 3 nm, 4 nm and 5 nm models. Finally, by comparing the MSD results at low and high temperature for each model, the dominant coalescence dynamics changes were obtained.