A New Adhesive for CoW Cu-Cu Hybrid Bonding with High Throughput and Room Temperature pre-Bonding

In this report, a new approach to high throughput, low-temperature chip on wafer hybrid bonding processes by using a unique adhesive is described. In our process, a bonding layer consisting of cured adhesive and slightly recessed Cu pads is fabricated on the chip surface, and the chip is bonded to another bonding layer consisting of SiO
2
and Cu pads fabricated on the target wafer. The chip is pre-bonded to the target wafer under compression for 1 second at room temperature by contacting the adhesive and SiO
2
. By using the slight film shrinkage of the adhesive in the Cu-Cu bonding process, the two facing Cu contact and compressed. As a result, batch annealing process without chip compression becomes possible. Experimental results for the proof of our process are reported.