摘要 |
<p>A method of polishing includes polishing a substrate having a second layer overlying a first layer, measuring a sequence of groups of spectra of light from the substrate while the substrate is being polished, each group of the groups of spectra including spectra from different locations on the substrate, for each group, calculating a value for a dispersion parameter of the spectra in the group to generate a sequence of dispersion values, and detecting exposure of the first layer based on the sequence of dispersion values.</p> |