Co Metal ALD on Cu with Cyclic Clean by Peroxide and Hydrazine for Inverse Hybrid Metal Bonding

To meet the demands of data-intensive applications such as artificial intelligence (AI) and high-performance computing (HPC), there is a need for tighter integration to minimize electrical interconnect delays and energy ^[1] . Typical I/O pitches for μ-bumps range from hundreds of microns to $\sim 50\mu \mathrm{m}$ for conventional flip chip bonding therefore limiting the number of I/O's. When scaling down solder-based μ-bumps, adjacent interconnects could be shorted during the bonding process. As a result, the investigation of new bonding techniques has become more and more popular. The feasibility of a 3D bonding technology for ultra-dense input/output (I/O) interconnects using cobalt selective atomic layer deposition (Co ALD) was explored with a preliminary testbed ^[2] .