Patent ID: 11972552
Assignee: PDF SOLUTIONS, INC.
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 10:
11. A method comprising:
obtaining a first plurality of sample images of semiconductor wafers formed on a semiconductor substrate, the first plurality of sample images including a plurality of different classes of defects appearing on the sample images;
applying a plurality of mathematical operators, individually or in various combinations, to each of the first plurality of images thereby generating a plurality of modified images, each modified image corresponding to a respective one of the plurality of sample images;
condensing the plurality of modified images to a plurality of single-dimensional representations, each single-dimensional representation defining a plurality of features for each corresponding modified image;
performing variable selection on each single-dimensional representation in order to select a smaller set of features from the plurality of features that are more important in determining the class of defect for the single-dimensional representation;
processing each corresponding single-dimensional representation m a plurality of machine-learning-based pairwise classifier models, each of the pair-wise classifier models configured to determine a corresponding probability that the single-dimensional representation is more indicative of one of a unique plurality of pairs of the plurality of different classes of defects; and
running a final machine-learning-based classifier model configured to assign one of the plurality of classes of defects to each corresponding single-dimensional representation on the basis of the determined probabilities from the processing step.