Fundamental Properties of Chemical Mechanical Polishing for Copper Layer Assisted by Optical Radiation Pressure

Abstract

This paper presents a corrective 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 component analysis and formation condition of aggregated particles were investigated, which is obtained by laser irradiation into the slurry on the copper surface. This result indicated that the aggregated marks were purely made of SiO₂ particles contained in slurry and the height of particle aggregation could be controlled by laser irradiation condition. Next, proposed planarization method for uneven surface of copper layer was attempted. As the polishing progressed, the height of aggregated marks was reduced. Then, it was confirmed that the aggregated marks play a role of masks, and no material removal at the bottom surface of recessed areas takes place during the polishing. This process made it possible to realize high planarity on copper surface.