欠陥集積による銅二結晶構造粒界割れ発生機構の分子動力学解析

抄録

In the field of semiconductor devices, miniaturization of the device materials used in their internals makes it possible to increase the processing capacity per unit area, and reduce the size and power consumption of the device. At present, copper wiring with low electrical resistivity and high thermal conductivity has become the most common metal wiring in advanced semiconductor devices. However, the drastic decrease in the area of cross-section should increase the resistance of interconnections, and thus, Joule heat and signal delay. In addition, the local internal stress also increases due to the interaction of the nearby stress concentration fields, and it causes the decrease in the reliability of products. Furthermore, the atomic diffusion acceleration phenomenon called Electro Migration (EM) under high current density degrades the lifetime of interconnections. Anisotropic diffusion of atoms along grain boundaries in the metal causes voids, hillocks, and micro cracks, resulting in wire breakage and short-circuit defects that reduce product reliability. Therefore, it is essential to quantitatively evaluate the degradation of the quality of boundaries under operating conditions and to understand the dominant factors in order to assure product reliability. In this study, the effect of static and dynamic strains perpendicular to the grain boundary was analyzed by molecular dynamics to determine the dominant factors of grain boundary strength such as vacancies, dislocation density, and structural change due to local strains.