Parallel spectroscopic ellipsometry system for fast correction of surface variability in metrology-based systems (Conference Presentation)

In interferometry based metrology systems, the sample’s topography is extracted from the interference phase which is determined by a combination of both the topography of the sample and its reflectance\transmission phase governed by the sample‘s structure and material composition. Since the two contributions cannot be distinguished, variations of the samples surface (surface variability) can be falsely interpreted as topography changes and undermine the reliability of interferometric measurement. For this reason, knowledge of the sample’s structure\composition is required to eliminate its effect on the interference phase, which is rarely available a priori. Spectroscopic ellipsometry is a well-known metrology technique for the determination of the optical and thus structural properties of multilayered samples with high accuracy through a measurement of some ellipsometric parameters. These parameters are extracted for each pixel in the sample by a combination of sequential measurements taken with a variation in the orientation of a polarizer or a compensator, or most commonly a rotating analyzer\compensator. Thus the acquisition time and throughput are limited in addition to the constraint of stationary sample during data acquisition (rotation) for noise and errors reduction. These techniques are not suitable for high throughput oriented production lines and dynamic samples where the sample is in constant motion. We present a novel fast spectroscopic ellipsometry system enabling the parallel acquisition of all necessary data enabling high speed and accurate sample characterization. This parallel spectroscopic ellipsometer is integrated with our dynamic focusing probe, allowing high-speed and surface variability immune interferometry based axial position tracking.