Linewidth roughness and cross-sectional measurements of sub-50 nm structures with CD-SAXS and CD-SEM

摘要

Critical dimension small angle X-ray scattering (CD-SAXS) is a measurement platform that is capable of measuring the average cross section and sidewall roughness in patterns ranging from (10 to 500) nm in pitch with sub-nm precision. These capabilities are obtained by measuring and modeling the scattering intensities of a collimated X-ray beam with sub-nanometer wavelength from a periodic pattern, such as those found in optical scatterometry targets. In this work, we evaluated the capability a synchrotron-based CD-SAXS measurements to characterize linewidth roughness (LWR) by measuring periodic line/space patterns fabricated with extreme ultraviolet (EUV) lithography with sub-50 nm linewidths and designed with programmed roughness amplitude and frequency. For these patterns, CD-SAXS can provide high precision data on cross-section dimensions, including sidewall angle, line height, line width, and pitch, as well as the LWR amplitude. We also discuss the status of ongoing efforts to compare quantitatively the CD-SAXS data with top-down critical dimension scanning electron microscopy (CD-SEM) measurements.