ABSTRACT
Chemical-Mechanical Planarization (CMP) remains hampered by systematic and random interlayered dielectric (ILD) thickness variation at the wafer and die level. Pattern dependencies within the die, in particular, have been of concern for both manufacturability and product design. In the ILD CMP process, the most important factor is the characteristics of nano fumed silica slurry. B. Lee et al. have systematically reported nanotopography impacts on oxide CMP, however, they quantified the impact using standard deviation of film thickness variation, which itself does not include lateral information. Particularly, CMP characteristics are strongly dependent on the pattern density of the chip layout. Although CMP can planarize over long-length scales, the pattern density variation across a chip leads to large variation in global thickness across the die. T. Fukuda et al. qualitatively showed the pad dependency with a comparison between the line profiles of the nanotopography of wafers and the film thickness variations after oxide CMP.
