The effect of plasma pre-cleaning on the Cu-Cu direct bonding for 3D chip stacking.

The effect of bonding temperature and plasma treatment on the interfacial adhesion energy of the Cu-Cu direct bonding layers was investigated under 4-point bending test method. Interfacial adhesion energies with increasing bonding temperature, Good-quality Cu to Cu bonding is achieved at the low bonding temperature of 250°C with surface treatment.