Effect of substrate surface roughness and parameters on the behavior of Cu nanoparticles sintering: A study by molecular dynamics simulation

Cu nanoparticle sintering technology, known for its low electromigration rate, superior electrical and thermal properties, and cost efficiency, is a promising method for high-power device packaging. Despite limited research on substrate conditions, this study uses molecular dynamics (MD) simulations to investigate how substrate surface roughness affects the quality of Cu nanoparticle sintered joints. Various surface roughness levels were simulated by arraying bumps of different heights on the Cu substrate. The findings indicate that a smaller roughness on the substrate enhances sintering quality, whereas a larger roughness detrimentally affects sintering quality. The effects of varying sintering temperatures, Cu nanoparticles and pressures were examined to address the challenge of improving sintering quality under conditions of greater roughness. Computational results reveal that an appropriate particle size can effectively fill surface defects. Additionally, increasing the sintering temperature and pressure significantly mitigates the negative impact of roughness on sintering quality. These results address substrate surface roughness and provide insights for optimizing the Cu nanoparticle sintering process.