Non-Planarization Cu-Cu Direct Bonding and Gang Bonding with Low Temperature and Short Duration in Ambient Atmosphere

Low temperature (150
^o
C) and short duration Cu-Cu direct bonding, without planarization, and gang bonding approaches are demonstrated with excellent bond strength, electrical characteristics, and reliability. The concept is based on the high stress-led inducing deformation and internal friction to achieve low temperature bonding. In addition, the bonding structure has the advantage of high roughness tolerance on surface without CMP requirement. Compared to current products using Cu-Cu direct bonding at 350-400
^o
C with long duration and vacuum requirement, the breakthrough of proposed schemes provides the feasibility for product realization in 3D integration packaging.