Abstract: Disclosed is a method for detecting electrical defects on test structures of a semiconductor die. The test structures includes a plurality of electrically-isolated test structures and a plurality of non-electrically-isolated test structures. The test structures each has a portion located partially within a scan area. The portion of the test structures located within the scan area is scanned to obtain voltage contrast images of the test structures' portions. In a multi-pixel processor, the obtained voltage contrast images are analyzed to determine whether there are defects present within the test structures. In a preferred embodiment, the multi-pixel processor operates with pixel resolution sizes in a range of about 25 nm to 200 nm. In another aspect, the processor operates with a pixel size nominally equivalent to two times a width of the test structure's line width to maximize throughput at optimal signal to noise sensitivity.

Abstract: Disclosed are methods and apparatus for designing an optical spectrum of an illumination light beam within an optical inspection system. A set of conditions for inspecting a film on a sample by directing an illumination light beam at the sample is determined. At least a portion of the illumination light beam is reflected off the sample and used to generate an image of at least a portion of the film on the sample. A plurality of peak wavelength values are determined for the optical spectrum of the illumination light beam so as to control color variation in the image of the film portion. The determination of the peak wavelengths is based on the determined set of conditions and a selected thickness range of the film. In one specific embodiment, the color variation is reduced, while in another embodiment the color variation is increased to enhance pattern contrast. An apparatus which implements the designed optical spectrum is also disclosed.