Advanced cell-to-cell inspection
First Claim
1. An electro-optical inspection method comprising:
- imaging at least a portion of a semiconductor wafer, wherein (i) the wafer includes at least two regions, including a first region comprising a plurality of memory cells of a first type and a second region comprising a plurality of memory cells of a second type, and (ii) a repetition vector of at least one type of cells is different from a repetition vector of at least one other type of cells;
accessing data that defines at least one repetition vector for each type of cells; and
inspecting each region using a cell-to-cell comparison method based on data including the at least one repetition vector for the type of cells in each respective region.
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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.
19 Citations
19 Claims
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1. An electro-optical inspection method comprising:
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imaging at least a portion of a semiconductor wafer, wherein (i) the wafer includes at least two regions, including a first region comprising a plurality of memory cells of a first type and a second region comprising a plurality of memory cells of a second type, and (ii) a repetition vector of at least one type of cells is different from a repetition vector of at least one other type of cells; accessing data that defines at least one repetition vector for each type of cells; and inspecting each region using a cell-to-cell comparison method based on data including the at least one repetition vector for the type of cells in each respective region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An electro-optical inspection method comprising:
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imaging at least one portion of a semiconductor wafer along an inspection path, wherein the wafer includes at least one region comprising a plurality of memory cells having a repetition vector that is perpendicular to the inspection path and is an only repetition vector associated with the at least one region; and inspecting the at least one portion of the semiconductor wafer using a cell-to-cell comparison method.
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13. An electro-optical inspection system, the system comprising:
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a light source configured to illuminate a wafer, an imager configured to image the wafer; and at least one processing unit configured to perform actions including;
(i) obtaining an inspection image of at least a portion of the wafer including at least two regions, each region having a repetition vector different from one another, (ii) accessing data that defines the repetition vector for each region, and (iii) inspecting each region using a cell-to-cell comparison method based on the repetition vector of each region. - View Dependent Claims (14, 15, 16, 17, 18)
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19. An electro-optical inspection system, the system comprising:
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a light source configured to illuminate a wafer; an imager configured to image the wafer along an inspection path; and at least one processing unit;
configured to perform actions including;(i) obtaining an inspection image of at least a portion of the wafer including a region defined by structural features having a repetition vector that is perpendicular to the inspection path and is an only repetition vector associated with the region, (ii) accessing data that defines the repetition vector, and (iii) inspecting the region using a cell-to-cell comparison method based on the repetition vector.
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Specification