Characterization of Die-to-Wafer Hybrid Bonding using Heterogeneous Dielectrics

To overcome the technological limitations of existing bonding technology using solder u-bumps, die-to-wafer (D2W) hybrid bonding technology is attracting attention. Hybrid bonding does not entail melting or re-solidification of metal and does not require an intermediate for the interconnection of the chip and substrate, as direct bonding is realized using Cu-pad and dielectrics. Consequently, this enables advancement in multiple aspects, including bump density, power efficiency, speed, bandwidth, and thermal dissipation. In this study, we studied D2W hybrid bonding characteristics using heterogeneous dielectrics. The characteristics of the bonding interface were evaluated for each of the heterogeneous oxide bonding and Cu-Cu bonding; The heterogeneous dielectrics combination has an adhesion strength that is 38.9% higher than that of CVD#1 homogeneous dielectric bonding at 2.5 J/m(2). When the vertical shape that materialized between the Cu pads was observed with TKD, it was confirmed that the grains between the upper and lower Cu pads expanded well in various directions, and the boundary of the interface disappeared. In addition, EELS analysis results confirmed that there was no Oxygen at the interface after bonding. HR-TEM also confirmed the bonding between Cu atoms. The aforementioned analyses verified the possibility of realizing D2W hybrid bonding with the currently designed structure. The proposed D2W technology is expected to replaces the conventional solder bonding technology at the advanced package.