| Abstract: | With the reduction of critical dimensions (CD) of physical gate lines, standard methods for evaluating bottom CD from the scanning electron microscope (SEM) signal become inaccurate. The two peaks, originating from the line edges, merge into a single peak, and the correct position of the topographical top and bottom points is not clear. A general Monte Carlo simulation program, developed to model SEM signals, was used to analyze the signals emerging from ultra small silicon lines. By correlating the simulated signals with the features, we deduced the location of the top and bottom points. This analysis was done for lines with various CDs, sidewall angles, and corner rounding, as well as for different spot sizes. This work shows the feasibility of using SEM for measuring ultranarrow features and supply data for algorithm development. |
