Application of PSD for the extraction of programmed line roughness from SAXS

For the most advanced nodes, line roughness reaches the same order of magnitude as the CD. It results in a huge impact on power consumptions and leads to some device failures. Hence, the control of this morphological aspect needs an adapted metrology. CD-SEM is considered as an adapted technique for roughness extraction. It is based on the PSD extraction that allows to obtain roughness information in frequency domain. CD-SAXS has been mentioned as one of the highest potential techniques for microelectronics by ITRS with an expected resolution better than one angstrom. The study presented in this article is based on programmed roughness simulations and first experimental measurements. It demonstrates that a complete PSD can also be extracted from a CD-SAXS analysis and that extended information of roughness can be so deduced. Comparison of SEM and SAXS proves the capability of SAXS technique for the PSD extraction of line roughness. Next challenges to improve this extraction are mentioned.