(Invited) Modified SAB Methods for Hybrid and All-Cu Bonding for 3D Integration below 200ºC

Two Surface Activated Bonding (SAB) methods will be proposed to enable low-temperature hybrid bonding for 3D integration. A modified one involves surface activation processes using Ar fast-atom-beam bombardment with simultaneous co-sputtering of Si nano-adhesion layer, followed by sequential plasma irradiation with N2 radicals. In the other one, we will connect two device wafers not in a hybrid but all-Cu bonding. A small insulation area surrounds the Cu pads on the wafer, while the rest is covered with Cu solid layers. These solid layers constitute the ground plane, power plane, or their paired layers and may contribute to heat dissipation when connected to thermal vias. The two wafers are connected only by bonding on the Cu electrodes and solid layers. Cu-Cu direct bonding is possible at room temperature by applying the standard SAB directly. Room-temperature bonding is overwhelmingly advantageous for bonding heterogeneous devices and wafers.