A novel design of brush scrubbing in post-CMP cleaning

Concentric and eccentric brush scrubbing behaviors of the hard disk drive (HDD) substrates in post-chemical mechanical polishing (CMP) process have been investigated with kinetic brush-disk contact trajectory analysis and hydrodynamic fluid velocity simulation as well as experimental studies. The adhesion forces as well as the hydrodynamic drag force for particle removal are also discussed. The brush nodules-disk contact trajectories with eccentric scrubbing cover the full surface of the disk, however, the trajectories with concentric scrubbing only accumulate on several concentric circular bands aligned along the discrete distribution of brush nodules. The fluid hydrodynamic force with eccentric scrubbing is larger than that with concentric scrubbing. The experimental results have found that the disk surfaces with eccentric scrubbing have approximately 40% lower particle count than that with concentric scrubbing. The modeling analysis and experimental results have found that the eccentric scrubbing has higher particle removal efficiency for the work piece with a hole at the center.