Scatterometry, an optical metrology technique for lithography

Scatterometry is an optical metrology technique designed for the characterization of test samples from lithography. These samples are diffraction gratings with the width of the lines reproducing the critical dimension. Scatterometry consists in ellipsometric measurements of the light diffracted from the samples in various experimental configurations and the fitting of the data to theoretic predictions. The parameters of the best fit are the most probable values for the parameters of the sample. Scatterometry involves optical instrumentation, diffraction theories, and data reduction and sensitivity analysis.