Combined Surface Activated Bonding Technique for Low-Temperature Cu/Dielectric Hybrid Bonding

Cu/dielectric hybrid bonding at low temperatures of no more than 200°C remains challenging because of the different features of Cu-Cu and dielectric-dielectric (such as SiO 2 -SiO 2 ) bonding. This paper reports a combined surface activated bonding (SAB) technique for low-temperature Cu-Cu, SiO 2 -SiO 2 , and SiO 2 -SiN x bonding. This technique involves a combination of surface irradiation using a Si-containing Ar beam and prebonding attach-detach process prior to bonding in vacuum. Wafer bonding experiments were conducted at either room temperature or 200°C. Results of bonding strength measurements, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) observations, and X-ray photoelectron spectroscopy (XPS) analysis were reported and discussed to understand the present combined SAB technique.