Molecular dynamics study of nanosilver particles for low-temperature lead-free interconnect applications

Molecular dynamics (MD) simulation was conducted to investigate the coalescence of Ag nanoparticles and their deposition on a gold substrate at various temperatures from 400 K to 1,000 K using the embedded atom method (EAM). Density distribution function, x-z plane projection, spreading index, and coalescence index were analyzed to gain more insight into the sintering and diffusion process. Simulation results showed that Ag and Au atoms can diffuse into each other significantly at a temperature of 1,000 K and reform the lattice structure after the temperature is cooled back to 400 K. Simulation data also demonstrated that even at a low temperature of 400 K, silver spheres can be collapsed and deposited on the substrate. Yet higher temperatures were helpful in enhancing the degree of collapsing and deposition.