Peeling and delamination in Cu/SiLK~(TM) process during Cu-CMP

摘要

One of the major challenges with integration of Cu/low-k or ultralow-k materials is to eliminate delamination during chemical mechanical planarization (CMP) process due to their porous nature and weak mechanical properties. Three different kinds of peeling at various metal levels—single layer peeling, multi-stack delamination and pattern design related—were generally observed in the CMP process of Cu/ SiLK~(TM). The single stack peeling is due to poor mechanical integrity of low-k materials with barriers. Based on the results of this study, multi-stack and pattern design related peelings were attributed to the degradation of adhesion caused by accumulation of stress. Critical pressure for CMP using Al_2O_3 and MnO_2 slurries was also determined for single and dual stacks. Robust CMP process for Cu/ SiLK~(TM) integration developed with new process concept will be discussed and seven layers of Cu/SiLK~(TM) metallization processed with dual damascene was successfully demonstrated.