Process Optimization in IMD Deposition: A Sucessful Application of Isothermal Fast Wafer-Level Electromigration

Abstract

In this work, we explore the effect of different IMD deposition tools on the occurrence of early electromigration (EM) failure. The failure is revealed by the fast Wafer Level Reliability (fWLR) method. It is found that under the same embedded IMD scheme (i.e. HDP FSG and then TEOS USG), the initial HDP FSG film deposition condition is the main cause for fWLR-EM early failure. It deteriorates subsequent USG film stress and imposes the stress on metal layers. This is also confirmed by Package Level Reliability EM (PLR-EM). Moreover, by understanding reliability risk caused by initial FSG film quality, we performed recipe improvement experiments and obtained better EM performance. The fWLR method proves its fast and accurate characterization capabilities in process development and monitoring.