Linear time EUV blank defect mitigation algorithm considering tolerance to inspection inaccuracy

Yuelin Du, Hongbo Zhang, Martin D.F. Wong

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Extreme ultraviolet lithography (EUVL) is a leading candidate for next generation lithography (NGL). At 11nm technology node, the size of the minimum printable multi-layer (ML) mask defect is as small as 20nm. As a result, it is extremely difficult to produce defect-free ML mask blanks. Instead, by allowing a certain number of printable defects on the blank, the EUVL cost of ownership can be tremendously reduced. However, those printable blank defects must be mitigated later in the mask fabrication process in order not to sacrifice yield. One effective defect mitigation approach is to cover the defects by device patterns, such that the defects will no longer be printable. However, there can be billions of device patterns in one single layer which have to be shifted together within a certain margin due to the exposure alignment requirement. Thus an efficient way to cover all defects simultaneously via global device pattern shifting is sorely needed. In addition, it is very difficult to measure the position of each defect accurately with the current blank inspection tool, so the defect position inaccuracy has to be taken into consideration at the same time. This paper formulates the blank defect coverage problem into a rectilinear polygon shrinking and intersection problem and develops a highly efficient algorithm whose time complexity is linear with respect to the density of device patterns. In addition, within the shift margin there are usually multiple positions to locate a layout on a defective blank where all defects are simultaneously covered by the device patterns; our algorithm is able to report the optimal layout location with the maximum tolerance for the inspection inaccuracy.

Original languageEnglish (US)
Title of host publicationPhotomask Technology 2012
EditorsFrank E. Abboud, Thomas B. Faure
ISBN (Electronic)9780819492609
StatePublished - 2012
EventSPIE Conference on Photomask Technology 2012 - Monterey, United States
Duration: Sep 11 2012Sep 13 2012

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceSPIE Conference on Photomask Technology 2012
Country/TerritoryUnited States


  • Absorber coverage
  • Defect mitigation
  • EUV
  • Inspection error tolerance

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Linear time EUV blank defect mitigation algorithm considering tolerance to inspection inaccuracy'. Together they form a unique fingerprint.

Cite this