3 April 2012 Compensation of CD-SEM image-distortion detected by View-Shift Method
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Abstract
Local-distortion of CD-SEM image can be detected and compensated by a unique technique: View-Shift method. As design rule of semiconductor device is getting shrunk, metrology by critical dimension scanning electron microscope (CD-SEM) is not only for measuring dimension but also shape, such as 2D contour of hot-spot pattern and OPC calibration-pattern. Accuracy of the shape metrology is dependent on the local image-distortion that consists of two components: magnification distortion and shape distortion. The magnification distortion can be measured by pitchcalibration method, that measures pitch of an identical line pattern at a lot of locations in image. However, this method cannot measure the shape distortion, that is for instance, bending of a uniform-width line. To measure accurately and quickly the image-distortion, we invented the View-Shift method, in which images of uniquetexture sample are taken before and after an image-shift by about 100nm. Between the two images we measure displacements of the unique-textures found at each grid-point spread over the image. Variation of the local displacements indicates the local image-distortion. In this work, we demonstrate a method to compensate the image-distortion detected by the View-Shift method. Due to the image-distortion, edge-points determined in SEM-image have already been dislocated. Such dislocation can be relocated to compensate the detected local-distortion. Onsite and on-demand compensation right before CD-SEM measurement for process monitoring is possible because we can quickly apply the View-Shift method and complete the compensation in a few minutes.
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Osamu Inoue, Osamu Inoue, Takahiro Kawasaki, Takahiro Kawasaki, Hiroki Kawada, Hiroki Kawada, } "Compensation of CD-SEM image-distortion detected by View-Shift Method", Proc. SPIE 8324, Metrology, Inspection, and Process Control for Microlithography XXVI, 832410 (3 April 2012); doi: 10.1117/12.915770; https://doi.org/10.1117/12.915770
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