DUAL BEAM SET-UP FOR SCATTEROMETER

摘要

A scatterometer or parousiameter having a dual beam setup and method for use thereof is provided for producing measurements of optical parameters. The dual beam parousiameter includes a hemispherical dome enclosure (318) sealed at the bottom with a base (320). A radiation source (302) produces radiation in two beams, an illumination beam (304) for illuminating a sample surface (308) and a calibration beam (330) for providing optical characterization information about the illumination beam (304). Each beam is guided into the hemispherical dome enclosure (318) via separate optical paths. An optical imaging device (324) is positioned to acquire an image of scatter radiation (314) scattered by the sample surface (308) illuminated by the illumination beam (304), and acquire an image of the calibration beam, simultaneously. The calibration beam image is used to compensate for variability in optical output of the radiation source (302) when analyzing the scatter radiation data.