分子動力学シミュレーションを用いたナノ粒子の低温焼結特性に関する数値解析

抄録

A sub-micron-sized metal particle has been used as a jointing material between a semiconductor device and a circuit electrode because of its low-temperature sintering characteristic. In this study, we have investigated a behavior of particles during heating using the molecular dynamics (MD) simulation, and we analyzed the driving force of low temperature sintering characteristic of particles. The Langevin equation and the Finnis-Sinclair potential were used on solving the equation. An Iron particles with a diameter of around 240 Å were heated at temperatures above/below the melting point (T_m) for the estimation of diffusion coefficient. The average diffusion coefficient near the center of the particle was 10^-5 cm²/sec at above T_m and was 10^-8-10^-9 cm²/sec at below T_m. On the other hand, the average diffusion coefficient at the outer layer of a particle becomes two or three orders in magnitude bigger than the center of the particle. It is conceivable that an enhanced sintering of nano-particles at low temperature is due to the high diffusion coefficient near the surface.