Method for detecting defects on wafers, system for detecting defects on wafers
AssigneeUnited Semiconductor (Xiamen) Co., Ltd.
InventorsYu Peng Hong, Qingrong Chen, Kai Ping Huang, Chin-Chun Huang, Wen Yi Tan
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Abstract
A method for detecting defects on a wafer including the steps of obtaining a reference image of a chip pattern formed on a reference wafer, using a computer algorithm to analyze the reference image to produce a division map for the chip pattern; setting respective thresholds for divisions of the division map, obtaining a comparison data between a test image of the chip pattern formed on a test wafer and the reference image, using the division map and the thresholds to examine the comparison data to identify a defect in the test image.
Claims11
A method for detecting defects on a wafer, comprising:
- obtaining a grayscale reference image of a chip pattern formed on a reference wafer;
- using a computer algorithm to analyze the grayscale reference image to produce a division map for the chip pattern, wherein the division map comprises a plurality of divisions;
- grouping the divisions according to the grayscale levels of the divisions, wherein the divisions are grouped into 5 to 10 groups;
- setting respective grayscale difference thresholds for the groups of the divisions, wherein a grayscale difference threshold of a group of darker divisions is smaller than a grayscale difference threshold of a group of whiter divisions;
- obtaining a grayscale difference data between a grayscale test image of the chip pattern formed on a test wafer and the grayscale reference image;
- and
- using the division map and the grayscale difference thresholds of the divisions to examine the comparison data to identify a defect in the grayscale test image.
A system for detecting defects on a wafer, comprising:
- an inspection tool, configured to obtain a grayscale reference image and a grayscale test image of a chip pattern;
- and
- a computer, configured to:
- analyze the grayscale reference image to produce a division map for the chip pattern, wherein the division map comprises a plurality of divisions;
- group the divisions according to the grayscale levels of the divisions, wherein the divisions are grouped into 5 to 10 groups;
- set respective grayscale difference thresholds for the groups of the divisions, wherein a grayscale difference threshold of a group of darker divisions is smaller than a grayscale difference threshold of a group of whiter divisions;
- calculate differences between the grayscale reference image and the grayscale test image to provide a grayscale difference data;
- and
- examine the grayscale difference data based on the division map and the grayscale difference thresholds of the divisions to identify a defect in the grayscale test image.
Dependencies are inferred from the claim text.