Low-temperature Adhesive Hybrid Bonding Technology with Novel Area-selective Passivation Layer

Hybrid bonding is a crucial technology in 3D IC integration, enabling the combination of different functional chips through vertical interconnections. However, in hybrid bonding, the issue of copper oxidation during the bonding of copper metal interconnects often necessitates bonding at high temperatures, leading to thermal budget concerns. In this study, we successfully develop a novel low-temperature polymer/copper hybrid bonding process with a silver passivation layer, achieved through an area-selective deposition method. Operating within the temperature lower than 200°C in an atmospheric environment, this area-selective deposition overcomes the high thermal budget challenge compared to traditional copper-to-copper bonding by mitigating copper surface oxidation. Additionally, unlike the physical vapor deposition (PVD) passivation layer, the area-selective deposition method eliminates the need for an additional photolithography process, thereby reducing both cost and processing time. This advancement positions the area-selective passivation layer as a promising candidate for low-temperature hybrid bonding technology.