US 11,972,552 B2
Abnormal wafer image classification
Tomonori Honda, Santa Clara, CA (US); Richard Burch, McKinney, TX (US); Qing Zhu, Rowlett, TX (US); and Jeffrey Drue David, San Jose, CA (US)
Assigned to PDF Solutions, Inc., Santa Clara, CA (US)
Filed by PDF Solutions, Inc., Santa Clara, CA (US)
Filed on Apr. 22, 2021, as Appl. No. 17/237,516.
Claims priority of provisional application 63/013,737, filed on Apr. 22, 2020.
Prior Publication US 2021/0334608 A1, Oct. 28, 2021
Int. Cl. G06K 9/62 (2022.01); G06F 18/2415 (2023.01); G06F 18/2431 (2023.01); G06N 5/04 (2023.01); G06N 20/00 (2019.01); G06T 7/00 (2017.01); G06V 10/44 (2022.01); G06V 10/764 (2022.01); G06V 10/82 (2022.01)
CPC G06T 7/0004 (2013.01) [G06F 18/2415 (2023.01); G06F 18/2431 (2023.01); G06N 5/04 (2013.01); G06N 20/00 (2019.01); G06V 10/454 (2022.01); G06V 10/764 (2022.01); G06V 10/82 (2022.01); G06T 2207/20076 (2013.01); G06T 2207/30148 (2013.01)] 20 Claims
OG exemplary drawing
 
1. 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 image types;
applying at least a first convolution function to each of the first plurality of images to generate a plurality of modified images each corresponding to a respective one of the plurality of sample images;
applying a pooling function to each of the modified images to form a plurality of corresponding vectors each defining a plurality of features for each respective modified image;
performing variable selection on each corresponding vector in order to select a smaller set of features from the plurality of features that are more important in determining image type for the vector;
processing each corresponding vector in a plurality of machine-learning-based pairwise classifier models, each of the pairwise classifier models configured to determine a corresponding probability that the vector is more like one of unique plurality of pairs of the plurality of different image types;
inputting the determined probabilities from the processing step into a final machine-learning-based classifier model configured to assign one of the plurality of image types to each corresponding, vector on the basis of the determined probabilities from the processing step; and
running the final machine-learning-based classifier model.