Effect of Contamination on a Test Object for SEM Calibration

Abstract

The effect of contamination on the relief of an MShPS-2.0Si test object for the calibration of a scanning electron microscope (SEM) is studied. The test object is grooves with a trapezoidal profile and large inclination angles of the side walls on the surface of silicon. It is shown that the largest distortions of the structure in the presence of contamination take place in regions adjacent to the region of scanning with an electron probe. The distortions in these regions are so large that these regions cannot be used for SEM calibration. The sizes of these regions reach 20 μm in the lengthwise direction along the grooves and 8 μm across when primary electrons with an energy of 15 keV are used for scanning. The region of scanning with an electron probe has small distortions, which allows one to use this region for SEM calibration. When using primary electrons with an energy of 15 keV and a probe current of 0.2 nA, the size of projections of the lateral inclined walls of the grooves does not change within seven scans. This allows one to use an MShPS-2.0Si test object up to a thousand times for SEM calibration (up to seven times in one spot).