Defect printability and inspection of EUVL mask

Defect printability and inspection studies were conducted on a programmed EUV defect mask. The mask was fabricated using Ta-based absorber stack on a Mo/Si multilayer coated 6025 plate. The defect pattern contains a variety of types of defects. The defect printing was performed on the Engineering Test Stand (ETS), which is the 0.1 NA ELTV scanner at Sandia National Laboratories in Livermore, CA. The result showed that the printability of defects depended on the defect type and that either notches in or protrusions from absorber lines were the first to print. The minimum printable defect size was approximately 15 nm (1X). Defect inspection was performed on a 257-nm wavelength mask inspection system in die-to-die mode. Seventy-eight out of 120 programmed defects were detected when using 50% detection sensitivity. Maximum detection sensitivity was also tried. However, the number of defects is overwhelmed by the nuisance defects. The minimum defect detected was 52 run, in width. Simulations with a 2-D scalar model are used to verify the results.