Laser-assisted CMP for copper wafer

This paper presents a laser-assisted Cu-CMP (Chemical Mechanical Polishing) method for obtaining higher planarized surface by forming laser aggregation particles on recessed areas of uneven copper surface before polishing. At first, the laser trapping of fine particles in slurry and the formation of aggregated marks on the copper wafer surface were investigated by fundamental experiments based on optical radiation pressure. Next, proposed planarization method for uneven surface of copper wafer was attempted. As the polishing processed, the height of aggregated marks was reduced. Then, it was confirmed that the aggregated marks played a role of masks, and no material removal at the bottom surface of recessed areas took place during polishing. This process made it possible to realize high planarity on copper wafer surface.