Abstract: Monte Carlo (MC) simulation techniques for the study of electron interaction with solids have been successfully applied to obtain the line-scan profiles in critical dimension scanning electron microscopy (CD-SEM). However, previous studies have been mostly concerned about the sample of simple geometries having sharp edges. The simulation was extended to the study of wave-type structures with smooth curved shapes. The MC model is based on using the Mott cross-section for electron elastic scattering and the full Penn algorithm in a dielectric function approach to electron inelastic scattering. The CD-SEM line-scan profiles of wave-type structures have been calculated by taking into account such experimental factors as primary beam energy, geometry parameters and material property. It is shown that by decreasing the height of the structure, the double side peaks can shrink to merge into a single peak. This characteristic will pose a challenge to the CD characterization for the smoothed line structure.