| 摘要 |
A method for optically measuring lithographic process bias of a minimum feature formed by a lithographic process. The method comprises creating on a substrate an array of elements from which a darkfield optical image is generated and detected, electronic information corresponding to the image is generated and processed, and the difference between the created length versus the nominal length of the elements is calculated to determine lithographic process bias. The darkfield optical image may be a double-lobe optical image, and signal processing may comprise creating a normalized intensity profile to overcome film-thickness dependencies, to which one or more noise-rejecting, edge-detection methods is or are applied to calculate the created length of the elements. A method for using double-lobe darkfield imaging for general edge detection is also disclosed.
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