Direct Transfer Bonding Technology Enabling 50-nm Scale Accuracy for Die-to-Wafer 3D/Heterogeneous Integration

Direct Transfer Bonding (DTB) is a promising technology for die-to-wafer bonding in 3D/heterogeneous integration, addressing limitations of conventional direct/hybrid bonding (DB/HB) methods such as pick-and-place or collective bonding. This paper describes advances in DTB technology that enable high-precision alignment and bonding of thin dies directly from carrier tape without contact with the die surface. This technology eliminates the need for chip-level handling, reducing contamination and damage. A key innovation is a high-accuracy alignment technique that recognizes alignment marks through a specially designed infraredtransparent carrier tape. The system successfully achieved $50-\text{nm}$ scale die/wafer alignment accuracy. In addition, this work investigated sputtered SiCN as a bonding interface material for improved bonding strength and void-free interfaces.