Effect of test object slope on SEM calibration

Abstract

The effect of the slope of a test object with a trapezoidal profile and high inclination of side walls on the calibration of a scanning electron microscope (SEM) is investigated. Being used as an attested parameter for the structure pitch or dimensions of upper and lower bases of hills and valleys, the slope of the test object does not affect the calibration of the SEM. However, when using the projection of the inclined side wall of hills and valleys onto the structure base to calibrate the SEM, the slope of the test object leads to a systematic error in determining the increase (of the pixelsize), which is several times larger than the random error. A method for determining the test object slope is developed that allows one to measure the slope, as well as evaluate and eliminate the systematic inaccuracy.