UV scatterometry

In this article are demonstrated the nanoscale capabilities of scatterometry, an optical metrology technique for the determination of the grating parameters. Notably, for both ellipsometric-scatterometry and phase-modulation scatterometry we are now currently using shorter wavelength laser sources, namely 325 nm in UV. We added to the scatterometer the ability to perform φ-scanning measurements. This capability adds new degrees of freedom to the sensitivity optimization procedure. Because the sensitivity analysis formalism leads us to the conclusion that sensitivity is provided mainly by anomalies, a rigorous analysis of a certain type of anomaly, the most likely to occur for our type of samples, was made using Modal Analysis. Our analysis allows for the prediction of the anomaly position. This procedure allows us to find the optimum measurement configuration much faster than the SAF formalism used in the past.