300 mm wafer-level hybrid bonding for Cu/interlayer dielectric bonding in vacuum

Wafer bonding technology is one of the key technologies for high-density three-dimensional integration. We demonstrated 300 mm wafer-level hybrid bonding with Cu and an interlayer dielectric (ILD) layer with the design of 1 × 1 μ m 2 pads with 2 μ m pitch. In this sequence of the bonding process, the structure of Cu bonding pads was controlled to be precisely convex to the ILD layer by chemical-mechanical polishing. Then the bonding process was performed in vacuum. Lastly, the bonded wafers were annealed at 200 °C for the postannealing process. As a result, hybrid wafer bonding with few voids was successfully accomplished.