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Proceedings Paper

CD-SEM image-distortion measured by view-shift method
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Paper Abstract

As the design rule for semiconductor device shrinks, metrology for the critical dimension scanning electron microscope (CD-SEM) is not only for measuring the dimension but also the shape, such as 2D contour of hot-spot pattern and OPC calibration-pattern. Accuracy of the shape metrology is dependent on distortion of CD-SEM image. The distortion of magnification in horizontal direction (i.e. x-direction) can be measured by pitch-calibration method, that measures pitch of identical vertical line patterns while view-shifting the identical pitch in x-direction. However, the number of measurement point could not be sufficient because this method requires long measurement time. Not only the horizontal magnification but also vertical magnification (i.e. y-direction) and shear deformation (i.e. distortion of shape) are necessary to keep highly accurate measurement. In this paper we introduce the view-shift method for quick and accurate measurement of the image-distortion. From using this method, both local distortion of magnification and shape can be measured in horizontal and vertical directions at once. Firstly, two SEM-images of evaluation sample are taken. The sample should have a lot of unique features, e.g. Textured-Silicon. View-shift about one ninth of the image size should be done by two images, and There are a lot of unique features in overlapped region between two images. As distribution of the unique features, displacement between two images indicates the local image-distortion. The dislocation of sample contour from distortion is estimated from the local-distortion. The image-dislocation on a tool evaluated in this paper is less than 0.5 nm. It is a tolerated size for current device process. However, it could be increased under the noisy external environment.

Paper Details

Date Published: 28 April 2011
PDF: 10 pages
Proc. SPIE 7971, Metrology, Inspection, and Process Control for Microlithography XXV, 79711Z (28 April 2011); doi: 10.1117/12.879032
Show Author Affiliations
Osamu Inoue, Hitachi High-Technologies Corp. (Japan)
Takahiro Kawasaki, Hitachi High-Technologies Corp. (Japan)
Miyako Matsui, Hitachi, Ltd. (Japan)
Hiroki Kawada, Hitachi High-Technologies Corp. (Japan)

Published in SPIE Proceedings Vol. 7971:
Metrology, Inspection, and Process Control for Microlithography XXV
Christopher J. Raymond, Editor(s)

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