Ion Beam Deposition for Defect-Free EUVL Mask Blanks

Abstract:
The availability of defect-free mask blanks is one of the most significant challenges facing the commercialization of extreme ultraviolet lithography (EUVL). The SEMATECH Mask Blank Development Center (MBDC) was created to drive the development of EUVL mask blanks to meet the industry’s needs. EUV mask defects come from two primary sources: the incoming mask substrate and defects added during multilayer deposition. For incoming defects, we have both an advanced in-house cleaning capability and an advanced in situ defect smoothing capability. This smoothing system uses combinations of ion beam deposition and etch to planarize any remaining incoming substrate defects. For defects added during multilayer deposition, we have an aggressive program to find, identify, and eliminate them. This paper summarizes progress in smoothing substrate defects and eliminating ever smaller multilayer-added defects. We will show the capability of our smoothing process to planarize our existing population of bump- and pit-type defects and will discuss how quickly this can be done. We will also discuss how many defects are added by the planarization process. In addition, we will show 53 nm sensitivity defect data for multilayercoated EUV mask blanks.