Metrology qualification of EUV resists

The ASML extreme ultraviolet lithography (EUV) alpha demo tool is a 0.25NA fully functional lithography tool with a field size of 26×33 mm 2 , enabling process development for sub-40-nm technology. Two exposure tools are installed in two research centers. The main topic of this paper is the examination of the measured pattern roughness LER contributed by measurement (SEM), exposure (EUV exposure tool) and the resists itself. The authors also examined suspected metrology SEM challenges on different EUV resist types exposed by one of the EUV demo tools. Standard CD SEM tests, such as precision and shrinkage were performed in order to get best working conditions. As part of the research, special attention was given to expected electron - material interactions, such as resist's slimming, low contrast and contamination build up on both lines. LER was analyzed in order to determine separately the contribution effect of the exposure tool and the different resists. Additional comparison was performed on different CDs with different orientations and densities.