Cu CMP Dishing Control for Fine Pitch Wafer-to-Wafer (W2W) Hybrid Bonding

Achieving uniform Copper (Cu) CMP dishing control across a wafer is vital to a successful wafer-to-wafer (W2W) hybrid bonding process. This paper discusses the issues faced when inappropriate slurry was used in CMP. Some of these include CMP removal variation across wafer, copper protrusion and dielectric surface rounding effect (which reduces bonding contact area). This paper investigates how the choice of slurry constituents can help to achieve the required dishing for successful W2W hybrid bonding.