Abstract: A method for evaluating placement errors within a lithographic mask, the method includes: providing or receiving a reference result that represents a distance between a reference pair of points of a reference element; measuring, for each pair of points out of multiple pairs of points that are associated with multiple spaced apart elements of the lithographic mask, the distance between the pair of points to provide multiple measurement results; wherein differences between a measurement result and the reference result are indicative of relative placement errors; and determining relative placement errors in response to relationships between the reference result and each of the measurement results.

Abstract: A method and system for evaluating an object that has a repetitive pattern. Illumination optics of an optical unit are adapted to scan a spot of radiation over a repetitive pattern that includes multiple regularly repeating structural elements that are optically distinguishable from their background, generating a diffraction pattern that includes multiple diffraction lobes. Collection optics are adapted to focus radiation from the repetitive pattern onto a detector. The focused radiation includes a single diffraction lobe while not including other diffraction lobes. A grey field detector generates detection signals, responsive to the focused collected radiation.

Abstract: A system, method and computer readable medium for reticle evaluation, the method includes: (i) obtaining, during an imaging process, multiple images of the reticle under different polarization and optionally interferometric conditions; and (ii) generating an output aerial image in response to (i) the multiple images and (ii) differences between the imaging process and an exposure process; wherein during the exposure process an image of the reticle is projected onto a wafer.

Abstract: A method of remotely measuring the temperature of a body, such as a semiconductor wafer, whose transparency varies with both wavelength and temperature and is characterized by an optical absorption edge. The body is illuminated at wavelengths on either side of the optical absorption edge. Based on the measured reflectivity at wavelengths shorter than the optical absorption edge, the direct reflectivity at wavelengths longer than the optical absorption edge is predicted and used to estimate the component of total reflectivity, at wavelengths longer than the optical absorption edge, which corresponds to propagation through the body and reflection back through the body. Light reflected from the body, measured in an "active" channel, is distinguished from light emitted passively by the body and measured in a "passive" channel. In the case of an opaque body, this allows the estimation of the emissivity of the body, and a temperature estimate based on Planck's law.