System and method for alignment in semiconductor device fabrication
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsYen-Liang Chen, Te-Chih Huang, Chen-Ming Wang, Chih-Ming Ke, Tsai-Sheng Gau
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Abstract
A method of determining overlay error in semiconductor device fabrication includes receiving an image of an overlay mark formed on a substrate. The received image is separated into a first image and a second image, where the first image includes representations of features formed on a first layer of the substrate and the second image includes representations of the features formed on a second layer of the substrate. A quality indicator is determined for the first image and a quality indicator is determined for the second image. In an embodiment, the quality indicators include asymmetry indexes.
Claims20
A method of determining overlay error in semiconductor device fabrication, the method comprising:
- receiving an image of an overlay mark formed on a substrate;
- separating the image into a first image and a second image, wherein the first image includes an image of features formed on a first layer of the substrate and the second image includes an image of the features formed on a second layer of the substrate;
- after separating the image into the first and second images, defining a background area of the second image;
- determining a distribution of pixel values for the background area;
- altering the pixel values for an unwanted portion of the second image according to the distribution of the pixel values for the background area;
- determining a quality indicator for the first image;
- and
- determining a quality indicator for the second image.
A method of determining overlay error in semiconductor device fabrication, the method comprising:
- receiving an image of an overlay mark formed on a substrate;
- separating the image into a first image and a second image, wherein the first image includes an image of features formed on a first layer of the substrate and the second image includes an image of the features formed on a second layer of the substrate;
- determining a quality indicator for the first image;
- wherein the determining the quality indicator for the first image includes:
- providing an average profile of the first image and an inverse of the average profile;
- generating a cross-correlation curve from the average profile and the inverse of the average profile;
- and
- calculating a first asymmetry index (AI) and a second AI using the cross-correlation curve;
- and
- determining a quality indicator for the second image.
A method of determining overlay error in semiconductor device fabrication, the method comprising:
- receiving an image of an overlay mark formed on a substrate;
- separating the image into a first image and a second image, wherein the first image includes an image of features formed on a first layer of the substrate and the second image includes an image of the features formed on a second layer of the substrate;
- and
- determining a quality indicator for the first image;
- wherein the determining the quality indicator for the first image includes:
- providing an average profile of the first image and an inverse of the average profile;
- generating a cross-correlation curve from the average profile and the inverse of the average profile;
- and
- calculating a first asymmetry index (AI) and a second AI using the cross-correlation curve.
Dependencies are inferred from the claim text.