Post-Cu CMP Leakage Suppression Using Sequential Small Molecular Inhibitor Treatment

In this study, we demonstrated that sequential SMI (Small Molecular Inhibitor) treatment for Cu/Low-k interconnects can achieve leak suppression comparable with that of SiCN. We developed two different SMIs for surface passivation: one selectively deposits on the Cu surface (SMI-Cu), and the other on the Low-k film surface (SMI-L). We also developed an innovative passivation process, depositing SMI-Cu on Cu followed by SMI-L to enable selective metal capping. This is referred to as "sequential SMI treatment." To characterize the impact on post-CMP queue time (Q-time), line leakage was tested repeatedly over five days after Cu-CMP. To investigate the effect of SMI treatment on Cu wiring, the changes in wire resistance and capacitance pre- and post-SMI treatment were observed. While the leakage current in the No Cap baseline increased significantly, and yield dropped to 0% within 80 hours, applying sequential SMI treatment successfully suppressed the increase in line leakage and maintained more than 90% yield over five days post-Cu-CMP. This leakage suppression effect is comparable to SiCN capping, and additionally, it provides improvements in both resistance and capacitance. Furthermore, by removing SMI-Cu from the Cu surface through H2 annealing, the same stable leakage performance is achieved.This new technique, utilizing sequential SMI approach, is a significant advantage in enabling metal cap applications on Cu interconnects in further advanced technology node.