Using Pattern Shift To Avoid Blank Defects During Euvl Mask Fabrication

Extreme Ultraviolet Lithography (EUVL) is the leading candidate for next generation lithography. EUVL has good resolution because of the shorter wavelength (13.5nm). EUVL also requires a new and complicating mask structure. The blank complexity and substrate polishing requirements result in defects that are difficult to eliminate or repair. Due to these challenges, shifting the pattern so that absorber covers the multilayer defects is one option for mitigating the multilayer defect problem. We investigated the capability and effectiveness of pattern shifting using authentic layouts. The rough indication of, "how many of what size defects are allowable", is shown in this paper based on the margin for the 11nm HP pattern. Only the twenty 300nm-sized defects are allowable for current location accuracy of the blank inspection and writing tools. On the other hand, sixty70nm-sized defects are allowable for the improved location inaccuracy. Furthermore we exercised the full process for pattern shift using a leading-edge 50 keV e-beam writer to confirm feasibility and it was successfully performed.