Tribological study of brush scrubbing in post-chemical mechanical planarization cleaning in non-porous ultralow-k dielectric Cu interconnects

Damage reduction during planarization is strongly required to avoid scratch generation and variation of electrical properties of low-k dielectrics that can lead to yield loss in an integrated circuit after implementation of an ultralow-k dielectric in Cu damascene interconnects. Three brush scrubbing conditions were found to realize high shear force for good particle removal. Having analyzed contact characteristics on an advanced non-porous ultralow-k dielectric fluorocarbon, brush scrubbing at a high rotation rate with a low down pressure is proposed to satisfy both sufficient particle removal efficiency and damage reduction during post chemical mechanical planarization cleaning. Tribological effects of down pressure and brush rotation rate on scratch and electrical properties of the ultralow-k fluorocarbon film are explored. To reduce the damage generated by the brush scrubbing process on the ultralow-k dielectric, it is important to make use of the effect of fluid flow by increasing the brush rotation rate at a low down pressure in advanced Cu interconnects in future.