Patent ID: 9619876
Date: 2017-04-11
CPC Classifications: G01N,G06T

Claim:
1. A computer-implemented method for detecting defects on a wafer, comprising: determining difference values for pixels in first output for a wafer generated using a first optics mode of an inspection system, wherein said determining comprises subtracting a characteristic of each of the pixels in the first output for a reference die on the wafer from the characteristic of its corresponding pixel in the first output for a test die on the wafer, determining other values for pixels in second output for the wafer generated using a second optics mode of the inspection system, wherein determining the other values comprises determining a value of another characteristic of each of the pixels in the second output for the reference die and the other characteristic of its corresponding pixel in the second output for the test die, and wherein the first and second optics modes are different from each other; generating a two-dimensional scatter plot of the difference values and the other values for the pixels in the first and second output corresponding to substantially the same locations in the test die, wherein said generating is performed prior to outlier detection and defect detection for the wafer, generating an additional two-dimensional scatter plot for the first output, the second output, or the first and second output, wherein at least one value used to generate the additional two-dimensional scatter plot is different from the difference values and the other values used to generate the two-dimensional scatter plot; detecting defects in the test die on the wafer based on the two-dimensional scatter plot and the additional two-dimensional scatter plot; and binning the defects based on which of the two-dimensional scatter plot and the additional two-dimensional scatter plot in which the defects were detected, wherein said detecting comprises identifying outliers in the two-dimensional scatter plot and determining if the outliers correspond to defects, wherein generating the two-dimensional scatter plot is further performed prior to identifying the outliers in the two-dimensional scatter plot and determining if the outliers correspond to the defects, and wherein determining the difference values, determining the other values, generating the two-dimensional scatter plot, generating the additional two-dimensional scatter plot, detecting the defects, and binning the defects are performed by a computer system.