Cost-Effective Low-Temperature Hybrid Bonding Using Layer Transfer Technology

Hybrid bonding has now become one of the most crucial technologies in the field of 3D IC. However, it requires a high degree of surface flatness and precise surface topography control, which increases the cost and complexity of the process. To overcome these challenges, we propose a cost-effective hybrid bonding technology by introducing a layer transfer technique. In this technology, the laser delamination method is used to de-bond the glass carrier from the bottom layer, which serves as the final hybrid bonding interface. From our findings, in-process heat accumulation is a key factor that damages the copper/polymer hybrid bonding interface. To address these issues, we introduce two kinds of diffusion barrier layers to protect the copper/polymer hybrid bonding interface from thermal damage. The diffusion barrier layer effectively mitigates the adverse effects of thermal exposure, ensuring the integrity of the hybrid bonding interface. Finally, we successfully demonstrate a cost-effective and low-temperature hybrid bonding result by Thermal Compression Bonding (TCB) under 200°C. The bonding result of this cost-effective hybrid bonding method is evidenced by cross-sectional SEM images and specific contact resistance measurements, confirming the great bonding result of our approach.