J061031 半導体薄膜配線材料のナノスケール結晶品質の評価に基づく信頼性設計

Abstract

With the high integration and the high speed operation of LSIs in recent years, interconnection material has rapidly changed over from conventionally used aluminum alloy to electroplated copper to improve the elevtronic performance of the LSIs. However, it was found that both the electronic characteristics and reliability of th electroplated copper thin films were rather low comparing with those of bulk copper. In this study, the authors clarified that the degradation of the electronic performance of the electroplated copper interconnections is caused by low crystallinity of the interconnectins and the grain boundary diffusion in the films is accelerated by the low crystallinity. The change of the crystallinity was observed by using an EBSD (Electron Back-scattered Diffraction) method. It was found that the crystallinity of the interconnection varied drastically depending on the electroplating conditions and seed layer material. Based on the results, the authors proposed a new design guideline for highly reliabile electroplated copper thin film interconnections.