Abstract: Disclosed are methods and apparatus for analyzing the Raze data provided by an optical inspection tool. The Haze data is analyzed so as to detect defects associated with the specimen surface. In general, the Haze data is first conditioned so that background noise which corresponds to low frequency variation on the specimen is separated or removed from the Haze data prior to analysis of such Haze data. In a specific embodiment, low frequency variations in the specimen surface are characterized, in effect, as an optical surface upon which an incident beam is directed. The Haze data that conforms to this resulting polynomial equation is then subtracted from the original Haze data to result in residual data, where slow variations in surface roughness are subtracted out, leaving possible defect information in the residual Haze data. This residual Haze data may then be analyzed to determine whether the specimen contains a defect.

Abstract: Disclosed are methods and apparatus for analyzing the Haze data provided by an optical inspection tool. The Haze data is analyzed so as to detect defects associated with the specimen surface. In general, the Haze data is first conditioned so that background noise which corresponds to low frequency variation on the specimen is separated or removed from the Haze data prior to analysis of such Haze data. In a specific embodiment, low frequency variations in the specimen surface are characterized, in effect, as an optical surface upon which an incident beam is directed. In one example, the Haze data that corresponds to the specimen surface is characterized with a polynomial equation, such as a Zernike equation. In other words, a polynomial equation is fit to the low frequency or background noise of the Haze data.