Kla Tencor Corporation

Kla-tencor Technologies Corporation

Ruifang Shi

Gaurav Verma

Carl Hess

Yalin Xiong

Xiaochun Li

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.

Wafer plane detection of lithographically significant contamination photomask defects

Provided are novel inspection methods and systems for inspecting photomasks to identify various defects using a model-based approach and information obtained from modeled images. Modeled or simulation images are generated directly from test or reference images. Some examples include aerial images that represent expected patterns projected by a lithography system on a substrate as well as photoresist images that represent expected resist patterns. Test images are first represented as a band limited mask pattern, which may include only linear terms for faster image processing. This pattern is then used to construct a modeled image, which in turn is used to construct a model-based feature map. This map serves as a base for inspecting the original test images to identify photomask defects and may include information that allows differentiating between various feature types based on their lithographic significance and other characteristics.

Reticle defect inspection with model-based thin line approaches

Optical proximity correction methods and apparatus are disclosed. A simulated geometry representing one or more printed features from a reticle is generated using an optical proximity correction (OPC) model that takes into account a reticle design and one or more parameters from a process window of a stepper. An error function is formed that measures a deviation between the simulated geometry and a desired design of the one or more printed features. The error function takes into account parameters (p. . . p) from across the process window in addition to, or in lieu of, a best focus and a best exposure for the stepper. The reticle design is adjusted in a way that reduces the deviation as measured by the error function, thereby producing an adjusted reticle design.

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Cupertino, CA, United States of America

Ruifang Shi