Sub-Nanometer Line Width and Line Profile Measurement Using STEM Images with Metal Coating

Abstract

The novel method of sub-nanometer uncertainty for the line width and line profile measurement using STEM (Scanning Transmission Electron Microscope) images is proposed to calibrate CD-SEM line width measurement. In accordance with the proposed method, the traceability and reference metrology of line width measurements are established using Si lattice structures. The interface of SiO2-Air is defined using image intensity of STEM image after metal coating. The edge positions of the Si line from top to bottom are detected. Then, the pixel size of the images is evaluated using 2D Fourier analysis for Si lattice structures. Using the proposed method, the line profile and line width of 50 nm are measured with expanded uncertainty less than 0.3 nm.