Study of an image stitching method for linewidth measurement

Wei Chu; Xuezeng Zhao; Joseph Fu; Theodore V. Vorburger

doi:10.1117/12.557767

20 August 2004 Study of an image stitching method for linewidth measurement

Wei Chu, Xuezeng Zhao, Joseph Fu, Theodore V. Vorburger

Proceedings Volume 5446, Photomask and Next-Generation Lithography Mask Technology XI; (2004) https://doi.org/10.1117/12.557767
Event: Photomask and Next Generation Lithography Mask Technology XI, 2004, Yokohama, Japan

Abstract

The interaction of probe and sample is a well known factor affecting the measurement accuracy of atomic force microscopy (AFM). The emergence of ultra-sharp carbon nanotube tips provides a good approach to minimizing the distortion of the measured profile caused by interaction with the finite probe tip. However, there is nearly always a significant tilt angle resulting when the nanotube is attached to an ordinary probe. As a result, we can obtain an accurate sidewall image of only one side of the linewidth sample rather than two sides. This somewhat reduces the advantage of using nanotube probes. To solve this problem, a dual image stitching method based on image registration is proposed in this article. After the first image which provides an accurate profile of one side of the measured line is obtained, we rotate the sample 180° to obtain the second image, which provides an accurate profile of the other side of the line. We keep the sidewall data for the better side of each image and neglect the data for the other side of each image. Then, we combine these better two sides to yield a new image for which the linewidth can be calculated. The sample is inevitably located at slightly different spatial positions in the two measurements. Image registration based on an improved iterative closest point (ICP) method was applied to remove the position difference between these two images. We are working to demonstrate that the calculated sidewall angle and linewidth value after registration and stitching is more accurate than obtained from only one image.

Citation Download Citation

Wei Chu, Xuezeng Zhao, Joseph Fu, and Theodore V. Vorburger "Study of an image stitching method for linewidth measurement", Proc. SPIE 5446, Photomask and Next-Generation Lithography Mask Technology XI, (20 August 2004); https://doi.org/10.1117/12.557767

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