Cu-Cu Thermo-compression Bonding for TSV Integration

We developed total solutions for the optically aligned Cu-Cu direct bonding process. The quantitative analyses of the interfacial adhesion energy and seam voids of Cu-Cu bonds performed with varying process parameters showed that bonding temperature and post-bond annealing have the most significant influence on bond properties. By optimizing experimental parameters, we could achieve, even with a short bonding time, the sufficient interfacial adhesion energy (>= 5 J/m(2)) with no interfacial voids. Post-bond annealing performed at 250-300 degrees C drastically improves the interfacial adhesion energy. SmartView alignment enables the face-to-face Cu-Cu bonding of non-IR transparent wafers while maintaining less than 0.2 mu m (3 sigma) and 1.0 mu m (3 sigma) of the pre-bond and post-bond alignment accuracy, respectively. Temporary bonding and debonding based on a new spin-on adhesive has such benefits as temperature stability up to 250 C, compatibility with bumped structures, short debonding time, low-temperature (<200 degrees C) slide-off release, easy cleanup with polar solvents, etc.