Abstract
The material removal mechanism of chemical mechanical planarization (CMP) has not been fully realized. Along with the stricter line rules in semi-conductor fabrication and the larger wafer size, the CMP technique faces more rigorous challenge. In CMP, material removal takes place between wafer and polishing pad, where the slurry distribution between wafer and polishing pad plays an important role. The current study models the phenomenon with transparent glass disk and dye added into slurry. A digital CCD camera was used for recording and analysis of the flow field between wafer and polishing pad. Further more, the influence of working conditions including platen speed, carrier speed, injection position, slurry flow rate, down pressure, wafer size, and pad type, were studied. It is expected that by rationalizing the distribution of flow field in CMP, the nonuniformity and material removal rate in the process can be improved. The experimental results demonstrate that the slurry film thickness between wafer and pad is influenced by pad type, wafer size, slurry flow rate, injection position, platen speed, and down pressure sorted by influence magnitude. While the nonuniformity of slurry distribution beneath the wafer is influenced by wafer size, carrier speed, down pressure, and pad type sorted as well.