Browsing by Author "Shyu, Deh-Ming"

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Analysis of the through-focus images with boundary-element method in high resolution optical metrology
(2006-10-01)
Shyu, Deh-Ming
;
Lu, Mao-Hong
;
光電工程學系
;
Department of Photonics
For through-focus focus metric we build a measurement system, in which a single diffraction-limited micro lens is used for imaging and a grating with a few pitches is used as a target. In this system, the optical field is calculated by the boundary-element method, in which a new algorithm is developed to reduce the dimension of a matrix. As a result, the memory capacity required in this calculation is much reduced up to 83% in our simulation case. An optimization of the grating structure is made to obtain the highest sensitivity for the critical dimension metrology. With the optimized grating structure the simulation shows a sensitivity of less than 1 nm in the through-focus focus metric. (c) 2006 American Institute of Physics.
High-resolution through-focus metric with two-pitch grating target
(2007-08-01)
Shyu, Deh-Ming
;
Lu, Mao-Hong
;
Ko, Chun-Hung
;
光電工程學系
;
Department of Photonics
Through-focus focus-metric is a method that is used to analyze images on a fixed plane with the help of focus-metric values when the target moves through the focus. In this study, an optical microscope having a magnification of 250x is constructed. A two-pitch grating target is imaged on a CCD detector and through-focus image data are measured. In addition, the optical field on the CCD detector is simulated using the boundary element method and physical optics propagation. By comparing the measured focus-metric signatures with the simulated signatures, information regarding the linewidth is obtained. The results show that the through-focus focus-metric method is a very sensitive method that can be used for measuring parameters such as the linewidth. Thus, a nanoscale resolution can be achieved. (C) 2007 Elsevier B.V. All rights reserved.