23 March 2009 Three-dimensional profile extraction from CD-SEM top-view image
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Emerging three-dimensional (3D) transistor structures have increased the demand for an easy and practical method to measure pattern feature metrics (such as CD, line-edge roughness, etc.) as a function of height (z coordinate). We have examined 3D pattern-profile extraction from a top-view image obtained using a critical-dimension scanning electron microscope (CD-SEM). An atomic force microscope (AFM) was used to measure 3D pattern profiles as a reference. In this examination, line-edge positions were firstly obtained from a CD-SEM image at various threshold levels, and the result was compared with the reference profile measured using the AFM. From this comparison, a mapping function from threshold levels of CD-SEM image-processing to z coordinates is obtained. Using this mapping function, 3D pattern profiles were reconstructed from CD-SEM signal profiles, and the obtained profiles were similar to the directly obtained cross-sectional profile. Put simply, a 3D pattern-profile was extracted from a top-view image successfully. Though the results are not sufficient to confirm the validity of our method yet, the method may feasibly be introduced for quick and easy 3D measurement.
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Atsuko Yamaguchi, Yoshinori Momonoi, Ken Murayama, Hiroki Kawada, Junichi Tanaka, "Three-dimensional profile extraction from CD-SEM top-view image", Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 72722G (23 March 2009); doi: 10.1117/12.816208; https://doi.org/10.1117/12.816208

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