Surface Topography Control on Cu Pad for Hybrid Bonding

Both wafer level and die level hybrid bonding is a vital for interconnect pitch scaling of advanced node chiplet/3D integration. The nano-level topography control before bonding is the crucial factor to realize high bonding yield. In this study, In-Situ corrosion behavior in the CMP by the slurry component was investigated in various methods. The difference of the corrosion current between Cu and Ta was able to be adjusted by H2O2 concentration. In addition, post-CMP cleaning may cause further recess of Cu pad while removing the carbon contamination. Therefore, we investigated the impact of post-CMP clean for Cu pad recess, as well as the N2 plasma, which is used to activate surface for bonding. XPS and AFM verified that the plasma activation could decompose BTA residues without increasing the surface roughness. These results foresee us the optimized surface topography formation process for fine pitch hybrid bonding.