US 11,921,052 B2
Inspection with previous step subtraction
Robert M. Danen, San Jose, CA (US); Sangbong Park, Milpitas, CA (US); Dmitri Starodub, Milpitas, CA (US); and Abdurrahman Sezginer, Monte Sereno, CA (US)
Assigned to KLA Corporation, Milpitas, CA (US)
Filed by KLA Corporation, Milpitas, CA (US)
Filed on Mar. 29, 2023, as Appl. No. 18/128,203.
Claims priority of provisional application 63/326,268, filed on Mar. 31, 2022.
Prior Publication US 2023/0316478 A1, Oct. 5, 2023
Int. Cl. G01N 21/88 (2006.01); G06T 5/00 (2006.01); G06T 5/50 (2006.01); G06T 7/00 (2017.01); H01L 21/66 (2006.01)
CPC G01N 21/8851 (2013.01) [G06T 5/002 (2013.01); G06T 5/50 (2013.01); G06T 7/001 (2013.01); G01N 2021/8887 (2013.01); G06T 2207/10024 (2013.01); G06T 2207/10152 (2013.01); G06T 2207/20081 (2013.01); G06T 2207/20224 (2013.01); G06T 2207/30148 (2013.01); H01L 22/12 (2013.01)] 38 Claims
OG exemplary drawing
 
1. An inspection system comprising:
a controller including one or more processors configured to execute program instructions causing the one or more processors to implement an inspection recipe by:
receiving first-step images of a plurality of sample regions after a first process step;
receiving second-step images of the plurality of sample regions after a second process step, wherein the second process step modifies the sample in at least one of the plurality of sample regions;
identifying one of the plurality of sample regions as a test region and at least some of the remaining sample regions as comparison regions, wherein the second-step image of the test region is a test image and the second-step images of the comparison regions are second-step comparison images;
generating a multi-step difference image by a weighted subtraction of a combination of at least one of the second-step comparison images and at least two of the first-step images from the test image; and
identifying defects in the test region associated with the second process step based on the multi-step difference image.