Combined surface activation bonding for Cu/SiO2 hybrid bonding for 3D integration

Low-temperature wafer bonding is important for fabrication of three-dimensional (3D) integrated systems. As a promising bonding approach, Cu/SiO₂ hybrid bonding at low temperatures of no more than 200 °C is in high demand but remains challenging. This paper reports a combined surface activated bonding (SAB) technique for low-temperature Cu/SiO₂ hybrid bonding. This technique involves a combination of surface activation using a Si-containing Ar beam irradiation and prebonding attach-detach process prior to bonding. Wafer-level bonding experiments of Cu-Cu and SiO₂-SiO₂ were conducted at 200 °C. Results of bonding strength measurements and transmission electron microscopy (TEM) were reported and discussed to understand the present combined SAB technique.