Application of actinic mask review system for the preparation of HVM EUV lithography with defect free mask

摘要

We introduce an extreme ultraviolet lithography (EUVL) mask defect review system (EMDRS) which has been developing in SAMUSNG. It applies a stand-alone high harmonic generation (HHG) EUV source as well as simple EUV optics consisting of a folding mirror and a zoneplate. The EMDRS has been continuously updated and utilized for various applications regarding defect printability in EUVL. One of the main roles of the EMDRS is to verify either mask repair or mask defect avoidance (MDA) by actinic reviews of defect images before and after the process. Using the MDA, small phase defects could be hidden below absorber patterns, but it is very challenging in case of layouts with high density patterns. The EMDRS clearly verify the success of the MDA while conventional SEM could not detect the images. In addition, we emulate images of the sub-resolution assist features (SRAFs) by the EMDRS and compared them with the wafer exposure results.