Applied Materials South East Asia Pte. Ltd.

Negevtech Ltd.

Oren Cohen

Erez Sali

Zeev Litichever

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.

Defect detection through image comparison using relative measures

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.

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Holon, Israel

Oren Cohen