Study of Extremely Low Temperature Organic Hybrid Bonding with Grain Engineered Cu

In this study, we demonstrated low-temperature organic hybrid bonding using Grain Engineered Cu (GE-Cu) as the electrode and polymer as the insulating layer to address the need for bonding at low temperature and to solve particle-related issues. At first, Chemical Mechanical Polishing (CMP) was applied to GE-Cu and polymer blanket wafers. The polymer that cured at high temperature showed low removal rates and low surface roughness, attributed to its high hardness. GE-Cu also showed low removal rates and low surface roughness due to the dilution and uniform distribution of impurities within grain boundaries. CMP was applied to patterned wafers as well to optimize Cu protrusion height and reduce surface roughness based on the results from blanket wafers. As a result, we successfully achieved organic hybrid bonding at an extremely low temperature of 150°C. Additionally, no defects were observed after temperature cycling tests. Furthermore, we examined the influence of bonding conditions and Cu protrusion height on the bonding interface.