Abstract: An optical inspection tool can automatically perform analysis/operations after the tool has generated data identifying defects (e.g. a defect list) from an inspection run of an object such as a semiconductor wafer. The tool can decouple post-inspection tasks from performing inspection runs so that one or more post-inspection tasks are performed on defect data from a previous inspection run while another inspection run is in progress. This can significantly improve the throughput of the tool when multiple inspections are performed, since the inspection run time effectively is shortened to include only the time the tool is actually used to acquire defect data. One or more post-inspection tasks can be performed, including, but not limited to, merging inspection runs, removing duplicate defects, removing straight-line false alarms, and characterizing defects.

Abstract: An optical inspection tool can feature a double-speed and other modes whereby the inspection rate is increased by using pixel binning. For instance, the tool may include an array of pixels provided by one or more detectors. Some or all of the pixels in one or more of the detectors may be binned according to inspection requirements. Based on the reduction in effective pixels due to the binning, in some embodiments, the rate of imaging and scanning rate of the wafer (or other object) can be increased. Different portions of the array may be binned differently to provide for increased throughput during inspections; for instance, the binning arrangement across an array can be correlated to the features that will be imaged using the array.

Abstract: A spatial mask printer may be used in conjunction with an optical inspection tool. The tool can be used to obtain a Fourier image of an inspected object, and a filter mask image can be designed to block certain aspects of the object's image in the Fourier plane corresponding to repetitive aspects of the imaged object. The filter mask image can then be printed and used in the tool during the inspection process. The mask image may be designed by hand or by computer and may be stored for later use. Filters may be automatically placed into the optical path of the inspection tool by a filter wheel, or may be housed in other filter banks. The printer may be configured to operate in a clean room environment, and may be integrated into the optical inspection tool.

Abstract: An optical inspection system or tool can be configured to inspect objects using dynamic illumination where one or more characteristics of the illumination is/are adjusted to meet the inspection needs of different areas. For example, the illumination intensity may be increased or decreased as the tool inspects areas of memory and periphery features in a wafer die. In some embodiments, the adjustment can be based on data obtained during a pre-inspection setup sequence in which images taken based on illumination with varying characteristics are evaluated for suitability in the remainder of the inspection process.

Abstract: Fast on-line electro-optical detection of wafer defects by illuminating with a short light pulse from a repetitively pulsed laser, a section of the wafer while it is moved across the field of view of an imaging system, and imaging the moving wafer onto a focal plane assembly, optically forming a continuous surface of photo-detectors at the focal plane of the optical imaging system. The continuously moving wafer is illuminated by a laser pulse of duration significantly shorter than the pixel dwell time, such that there is effectively no image smear during the wafer motion. The laser pulse has sufficient energy and brightness to impart the necessary illumination to each sequentially inspected field of view required for creating an image of the inspected wafer die. A novel fiber optical illumination delivery system, which is effective in reducing the effects of source coherence is described.

Abstract: Inspection of objects, such as semiconductor wafers, can be performed using a diluted scan wherein not all of an inspected area is actually imaged. Instead, a dilution plan can be devised based on the desired amount of area to be skipped and the particular parameters of the inspection, such as the size of each unit area to be imaged or not imaged and the distribution features of the wafer. When the same area is inspected in multiple wafers, the wafers can be inspected in sets using a dilution plan whereby a wafer (or inspected area) can be statistically inspected using diluted scans of the set of wafers. Similarly a die or group of dies of a specified type can be statistically inspected using diluted scans of a set of dies (or group of dies). When statistical inspection is used, the end results of such inspections, such as defect densities and distributions, can be corrected to account for inaccuracies that may be introduced when certain portions are imaged more often than others due to the dilution plan.

Abstract: Inspection of objects such as semiconductor wafers can include comparisons of shapes between inspection and reference images. As part of the inspection process, relative values may be assigned to pixels within each image based on comparison of such pixels to neighboring pixels. For instance, the pixels may be ranked by relative brightness in each image. Alternatively, directional vectors may be defined based on slopes between pixels and their neighbors. Various comparison metrics may be utilized to determine the degree of correlation between the relative values for pixels in the inspection image and corresponding pixels in the reference image. Relative values may be combined with conventional techniques as part of an inspection process. The inspection may be performed using an optical inspection tool that uses conventional techniques to identify defect candidates, with relative value analysis performed on areas containing defect candidates to confirm or deny the existence of a defect.

Abstract: Inspection of objects such as semiconductor wafers may proceed on a cell-to-cell or die-to-die basis. An image of a wafer may be obtained and the cells or dies shown therein can be inspected using any combination of appropriate die-to-die or cell-to-cell inspection methods. For example, one or more areas may be designated for cell-to-cell inspection. For each cell type, a reference image can be generated by obtaining an image of the area and displacing the image by an amount equal to the repetition vector for that cell type in opposite directions. The displaced images and the original image can be combined into a single reference image. The original image can then be compared to the reference image. In some embodiments, the displaced images are also compared to the reference image to statistically determine the presence or absence of defects.

Abstract: An optical inspection system or tool can be configured to adjust the distribution of light by using one or more diffusers. The diffusers can be variable in some embodiments. For example, the angular or spatial distribution of the illumination can be adjusted to minimize intensity of illumination outside of an imaged area to thereby reduce illumination loss. The angular or spatial distribution may additionally or alternatively be adjusted so that the illumination across an illuminated area is substantially uniform. The use of one or more diffusers may aid in the inspection of semiconductor objects including, but not limited to, semiconductor wafers and the like.

Abstract: Fast on-line electro-optical detection of wafer defects by illuminating with a short light pulse from a repetitively pulsed laser, a section of the wafer while it is moved across the field of view of an imaging system, and imaging the moving wafer onto a focal plane assembly, optically forming a continuous surface of photo-detectors at the focal plane of the optical imaging system. The continuously moving wafer is illuminated by a laser pulse of duration significantly shorter than the pixel dwell time, such that there is effectively no image smear during the wafer motion. The laser pulse has sufficient energy and brightness to impart the necessary illumination to each sequentially inspected field of view required for creating an image of the inspected wafer die. A novel fiber optical illumination delivery system, which is effective in reducing the effects of source coherence is described.

Abstract: An inspection system can support operation in multiple states. For instance, when inspecting an article, such as a semiconductor wafer, the tool can switch between imaging multiple locations using respective detectors to another operating state wherein multiple detectors operating in multiple imaging modes inspect a single location. An inspection system may combine the use of multiple detectors for multiple locations and the use of multiple viewing angles or modes for the same locations and thereby achieve high throughput. The different imaging modes can comprise, for example, different collection angles, polarizations, different spectral bands, different attenuations, different focal positions relative to the wafer, and other different types of imaging.

Abstract: A method for inspecting a wafer including a multiplicity of dies, the method including dividing an image of at least a portion of the wafer into a plurality of sub-images each representing a sub-portion of the wafer and selecting at least one defect candidate within each sub-image by comparing each sub-image to a corresponding sub-image of a reference including a representation, which is assumed to be faultless, of the portion of the wafer.

Abstract: An inspection system for inspecting an object, the system comprising an illuminator including at least one pulsed light source, a detector assembly, and a relative motion provider operative to provide motion of the object relative to the detector assembly, along an axis of motion, the detector assembly comprising a plurality of 2-dimensional detector units whose active areas are arranged at intervals.

Abstract: A method for inspecting a wafer including a multiplicity of dies, the method including dividing an image of at least a portion of the wafer into a plurality of sub-images each representing a sub-portion of the wafer and selecting at least one defect candidate within each sub-image by comparing each sub-image to a corresponding sub-image of a reference including a representation, which is assumed to be faultless, of the portion of the wafer.

Abstract: In an optical inspection tool, an image of an object under inspection, such as a semiconductor wafer, may be obtained using imaging optics defining a focal plane. Light comprising the image can be detected using multiple detectors which each register a portion of the image. The image of the object at the focal plane can be split into two, three, or more parts by mirrors or other suitable reflecting elements positioned tangent to the focal plane and/or with at least some portion at the focal plane with additional portions past the focal plane so that the focal plane lies between the imaging optics and the splitting apparatus. In some embodiments, reflective planes may be arranged to direct different portions to different detectors. Some reflective planes may be separated by a gap so that some portions of the light are directed while some portions pass through the gap.

Abstract: In an optical inspection tool, an image of an object under inspection, such as a semiconductor wafer, may be obtained using imaging optics defining a focal plane. Light comprising the image can be split into portions that are detected using multiple detectors which each register a portion of the image. The image of the object at the focal plane can be split into two, three, or more parts by polarization-based beam splitters and/or lenses positioned tangent to the focal plane. The splitting apparatus may comprise a pair of arrays of half-cylinder lenses comprising a convex side and a flat side. The arrays can be positioned with the cylinder axes perpendicular to one another and the flat sides facing each other. Thus, the pair of arrays can divide incoming light into a plurality of rectangular portions without introducing non-uniformities which would occur if several spherical lenses are configured for use in a rectangular array.

Abstract: Fast on-line electro-optical detection of wafer defects by illuminating with a short light pulse from a repetitively pulsed laser, a section of the wafer while it is moved across the field of view of an imaging system, and imaging the moving wafer onto a focal plane assembly, optically forming a continuous surface of photo-detectors at the focal plane of the optical imaging system. The continuously moving wafer is illuminated by a laser pulse of duration significantly shorter than the pixel dwell time, such that there is effectively no image smear during the wafer motion. The laser pulse has sufficient energy and brightness to impart the necessary illumination to each sequentially inspected field of view required for creating an image of the inspected wafer die. A novel fiber optical illumination delivery system, which is effective in reducing the effects of source coherence is described.