Plasma-Activated Cu-Cu and Al-Al Direct Bonding for Electronics Packaging

In this paper, we report Ar/N
2
plasma-activated Cu-Cu and Al-Al direct bonding performed at room temperature in ambient environment. Surface study is investigated on the Cu and Al surfaces before and after plasma activation. The results indicate that the plasma-activated surfaces are able to remain in an “activated” state for ~6 hours compared to the as-deposited Cu and Al surfaces. The plasma-activated Cu and Al dies are subsequently bonded and annealed in batch. The bonded dies are examined where the results show that a superior-quality bonding is achieved. This reported bonding technology would be suitable for high-throughput CMOS-MEMS 3D integration and electronics packaging.