[en] We have applied a coherent scattering microscopy (CSM)system to the analysis of aerial images for extreme ultra violet (EUV)masks. Measurements of aerial images for sub 22nm node were performed. Results for critical dimension (CD)measurements showed that reliable actinic CD measurements were possible even down to 12nm node using the CSM system. Detailed descriptions of the system and analysis procedures will be given together with the analysis results for line and space and contact hole patterns of EUV masks for various technology nodes

[en] Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics with a completely different configuration than those of conventional photolithography. This study investigated the etching properties of indium tin oxide (ITO) binary mask materials for EUVL, such as ITO (absorber layer), Ru (capping/etch-stop layer), and a Mo-Si multilayer (reflective layer), by varying the Cl₂/Ar gas flow ratio, dc self-bias voltage (V_dc), and etch time in inductively coupled plasmas. The ITO absorber layer needs to be etched with no loss in the Ru layer on the Mo-Si multilayer for fabrication of the EUVL ITO binary mask structure proposed here. The ITO layer could be etched with an infinitely high etch selectivity over the Ru etch-stop layer in Cl₂/Ar plasma even with a very high overetch time.