Analysis on Via-hole Filling Rrocess in Multilayred LSI Interconnection

点击翻译按钮获取中文摘要

As recent advances on LSI (large scale integrated circuit) technology requires further reduction of the size, multilayred structure has been intensely investigated. The forming process of interconnection between the layrs is one of the key issues in order to accomplish the structure. The reflow, in which the via-hole is filled with the conductor metal by the surface diffusion, is a promising method though the detail in the process has not been clarified yet. In this study, the process is numerically simulated for a two-dimensional model (filling into a groove) and an axi-symmetrical one (filling into a circular cylinder) solving the differential equation of surface diffusion by a finite dellevence method. The results show that the perfect filling can not be achieved for the groove or the cylinder with the aspect ratio, (depth/half width) or (depth/radius), larger than 3. Feasible conditions for the perfect filling are illustrated in a map for reader's convenience. The time for the filling, which is strongly dependent on the size and aspect ratio of via-hole, is discussed. Moreover, the process in incomplete filling is analyzed and the modified shape of via-hole is proposed on the basis of the simulation. The diffusion process is simurated in atomic level in detail using molecular dynamics under constant tempelature.