Method and apparatus for inspecting wafer defects

摘要

Methods and apparatus for inspecting a feature on a wafer surface are provided. In one aspect a method of inspecting a feature on a film surface is provided that includes illuminating the feature with laser radiation and detecting radiation scattered from the feature with a plurality of detectors. Each of the plurality of detectors has a known position. A position of the feature observed by each of the plurality detectors is computed based upon the radiation scattered from the feature. An average position of the positions observed by each of the plurality of detectors is computed. A first value for each of the plurality of detectors is computed that is the scalar product of the known position of a given detector with the difference of the position of the feature observed by that given detector and the average of the positions observed by each of the plurality of detectors. A second value or scatter height descriptor indicative of the topography of the feature is computed by summing first values for the plurality of detectors.