Kla-tencor Technologies Corporation

George Q Chen

Lih-Huah Yiin

Yu Long Cao

Jun Ye

Yen-Wen Lu

Mark Joseph Wihl

David Alles

Aditya Dayal

Pei-Chun Chiang

A method and apparatus for inspecting specimens or patterned transmissive substrates, such as photomasks, for unwanted particles and features, particularly those associated with contacts, including irregularly shaped contacts. A specimen is illuminated by a laser through an optical system comprised of a laser scanning system, individual transmitted and/or reflected light collection optics and detectors collect and generate signals representative of the light transmitted by the substrate. The defect identification of the substrate is performed using those transmitted light signals. Defect identification is performed using an inspection algorithm by comparing image feature representations of a test specimen with a reference specimen, and using a boundary computer and flux comparison device to establish tight boundaries around contacts and compute flux differences between the test and reference specimen contacts. Defect sizes are reported as ratio of flux difference, and entire contacts are highlighted for review.

Closed region defect detection system

Faster and more accurate techniques for displaying images are described. The techniques can be applied in various applications that include semiconductor fabrication processes. The invention uses preprocessed images to generate a user-selected image in order to increase the speed of image processing. The invention displays the pixels forming an image using grayscale shading in order to improve the accuracy of displaying the patterns used in photolithography processes. The techniques of the present invention can be used to display images that represent lithography patterns stored within memory devices or to display images captured by inspection or metrology devices.

Visualization of photomask databases

The present invention discloses methods of conducting surface inspections using summed light. One method includes the steps of measuring summed light intensity values for the substrate, generating comparison values for the substrate, and then comparing the measured summed light intensity values with the comparison values to determine whether there are defects in the substrate. In another embodiment, a method includes the steps of generating a reference cluster using measured summed light intensity values for selected portions of the inspection surface. Other summed light intensity values are measured and then compared with the reference cluster. Using this comparison, a determination is made as to whether a defect is present. Another embodiment uses a constant baseline signal which is compared to actual light intensity values to determine whether a substrate defect is present. In yet another embodiment a substrate is inspected for the presence of defects by conducting a pixel-by-pixel summed light inspection of the substrate.

Surface inspection system and method using summed light analysis of an inspection surface

Techniques that use the design databases used in each of the expose/etch steps during construction of phase shift masks are described. A model or reference image is rendered, accounting for systematic variations, from the design databases to represent what a layer of the PSM should look like after processing. The reference image is compared to an optically acquired image of a specimen phase shift mask to find defects. The technique of the present invention can be used to inspect EAPSM, APSM and tritone masks. The technique inspects all layers in one pass and is therefore more efficient.

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Fremont, CA, United States of America

George Q Chen