Micron and Nanometer Measuring Methods Based on Metrological Scanning Electron Microscope

Micron and nanometer dimensional metrology is an important part of integrated circuits manufacturing system and nanofabrication research work. Semiconductor device feature size has shrunk from the micron to dozen of nanometers. How to watch the micro structure clearly, identify its edge, and measure its dimension accurately are the major issues that need to be research. In this paper, a metrological scanning electron microscope (M-SEM) system with precision stage and laser interferometer is presented. Furthermore, this paper focuses on demonstrating a metrological SEM image edge detection algorithm which is the essential part of the metrological SEM system to realize the measurement of line width. The procedure of the algorithm is that SEM image is first analyzed by noise type according to the histogram characteristics. Then the image noise is reduced by specific filters. Furthermore, a specific interesting object image region is selected and pixel gray level values of the region are obtained by line scan. SEM image edges are determined by the characteristic of the pixel information in two possible cases. This algorithm preserves the edge details of the original image and detects the image edge automatically in an easy and fast way.