Low-Temperature Wafer-to-Wafer Hybrid Bonding by Nanocrystalline Copper

Three-dimensional heterogeneous integration is at the core of development for advanced package technology, evolving several applications including mobile, HPCs, and AI. In this paper, we have proposed wafer to wafer hybrid bonding by using the solderless nc-Cu and nc-Cu/SiO 2 hybrid structure with a pronouncedly reduced bonding temperature of 150°C for 1 hour. The bonding strength was near to 12 J/m ² between jointed two nc-Cu blanket wafers with an extremely strong bonding interface. For the first time, we have successfully bonded at a low temperature of 150 ° C, with distinctive materials and composite structures.