US 2011/0299758 A1 · Wafer Plane Detection of Lithographically Significant Contamination Photomask Defects

Abstract

Provided are novel methods and systems for inspecting photomasks to identify lithographically significant contamination defects. Inspection may be performed without a separate reference image provided from a database or another die. Inspection techniques described herein involve capturing one or more test images of a photomask and constructing corresponding test “simulation” images using specific lithographic and/or resist models. These test simulation images simulate printable and/or resist patterns of the inspected photomask. Furthermore, the initial test images are used in parallel operations to generate “synthetic” images. These images represent a defect-free photomask pattern. The synthetic images are then used for generating reference simulation images, which are similar to the test simulation images but are free from lithographically significant contamination defects. Finally, the reference simulation images are compared to the test simulation images to identify the lithographically significant contamination defects on the photomask.

Claims21

Dependent claims

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.

5 more elements

Dependencies are inferred from the claim text.

Wafer Plane Detection of Lithographically Significant Contamination Photomask Defects

Life of this patent

Wafer Plane Detection of Lithographically Significant Contamination Photomask Defects

Life of this patent

Abstract

Claims21