brush scrubbing

Brush scrubbing uses rotating brushes with chemicals or DI water to physically dislodge stubborn particles from wafer surfaces. **Mechanism**: PVA (polyvinyl alcohol) brushes rotate against wafer surface while chemicals flow. Mechanical force removes adhered particles. **When needed**: Particles too strongly attached for megasonic or chemistry alone. Post-CMP clean is major application. **Brush material**: PVA foam - soft enough not to scratch, effective for particle capture. Nodules or patterns for scrubbing action. **Process**: Wafer rotates while brushes contact surface. DI water, dilute ammonia, or other chemistries provide lubrication and particle removal. **CMP post-clean**: Critical to remove slurry particles and residues. Double-sided brush scrubbing common. **Limitations**: May cause scratches if particles are hard or brush is worn. Not for delicate structures. **Double-sided**: Clean both wafer surfaces simultaneously. Important for backside cleanliness. **Integration**: Part of post-CMP clean sequence with megasonic, chemicals, and spinning rinse/dry. **Brush lifetime**: Limited use cycles. Regular replacement required.