Patent ID: 8611637
Filing Date: 2013-12-17
Classification: G03F

Abstract:
1. A method for inspecting a photomask to identify lithographically significant contamination defects, the method comprising: providing the photomask comprising one or more printable features and one or more non-printable features, the photomask configured to achieve lithographic transfer of the one or more printable features onto a substrate using a lithography system; producing test images of the photomask using an inspection apparatus, the test images comprising a test transmission image and a test reflection image; providing a model of the lithography system to be employed in the lithographic transfer; constructing test simulation images by applying the model of the lithography system to the test images; constructing synthetic reference images from the test images by removing defects from the test images; constructing reference simulation images from the synthetic reference images by applying the model of the lithography system to the synthetic reference images, wherein the reference simulation images are constructed to be free of the lithographically contamination significant defects; and comparing the test simulation images to the reference simulation images to identify the lithographically significant contamination defects.