Optimization of TaSix absorber stack for EUV mask

We evaluated and optimized Ta-based absorber added by Si for EUV mask. Consequently, we confirmed TaSix based bi-layer absorber stack has the following performances; It has amorphous morphology without columnar structure advantageous to fabricate fine pattern with smaller line edge roughness. In order to realize better position accuracy, it has low internal stress capable to control. As an optical property, it has low DUV reflectance at 257nm which facilitates to perform defect inspection. As it can be etched anisotropcally by conventional halogen gases without using hard mask, we achieved almost vertical sidewall profile of 120nm lines and spaces pattern and promising CD control accuracy.