Wafer inspection tools with the capability to perform in-line or on-line measurement of roughness and dishing will improve the process development and production efficiency of chemical-mechanical polishing (CMP) processes. To this end, this research experimentally studied light scattering characteristics of post CMP W and Cu pattern wafer surfaces that inherently have roughness and metal dishing on their various regions with different metal linewidths and pattern densities. The surface scatter from the patterned W wafer surface is found to be dominated by W roughness, while the surface scatter from the patterned Cu wafer surface is found to be dominated by Cu dishing. The differences between W and Cu wafer scattering characteristics are then correlated to their topography characteristics. This paper provides a quantitative method to measure metal roughness and a qualitative method to characterize metal dishing as a function of linewidth and pattern density.
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