Localized power spectral density analysis on atomic force microscopy images for advanced patterning applications

Power Spectral Density (PSD) is now a standard analysis for pattern roughness process control in advanced patterning. Due to PSD analysis sensitivity coupled with Scanning Electron Microscopy (SEM), line edge roughness (LER) and line width roughness (LWR) are more understood. However, this is applied on sides of the line, and has limited information about roughness on top of the pattern. On the other hand, Atomic force microscopy (AFM) measure accurately the topography of pattern and even if this metrology is probe size dependent, the top of the patterned lines is well revealed when trenches are too narrow to be measured. In this work, we have adapted and applied the PSD analysis on patterned lines measured by AFM. Specific algorithm has been developed to localize the analysis on top of the line. This allow us to report on the effect of processes, such EUV resist smoothening and Area Selective Deposition (ASD).