Low-Temperature Nanocrystalline Cu/polymer Hybrid Bonding with Tailored CMP Process

The fine-pitch hybrid bonding technique allows for high integration density in advanced packaging. This paper demonstrates the nanocrystalline copper (nc-Cu)/polymer hybrid structure for both wafer-to-wafer as well as die to wafer hybrid bonding process. The nc-Cu material can be filled in photosensitive polymer material, with an average grain size of approximately 80 nm. Moreover, chemical mechanical polishing with tailed method attributes good interface for the nc-Cu and polymer layers bonding performance, achieving a roughness Ra of 0.26 nm and tailored dishing of 7 nm. The hybrid bonding process was completed by using a 10 μm fine-pitch nc-Cu/polymer with hybrid structure, can be bonding with pronouncedly reduced temperature of 150 °C. Both nc-Cu/polymer with distinctive properties have shown promising candidate toward hybrid bonding and interconnections in foreseeable future. In summary, this study have focus on the nc-Cu/polymer with tailored CMP. Such extraordinary interconnection technology with low temperature hybrid bonding can be achieved and shown great potential candidates in advanced packaging.