Results from a novel EUV mask inspection by 193nm DUV system

The semiconductor industry recently concluded that EUV lithography is the most promising candidate to replace ArF for the 22nm half-pitch node and beyond. Significant progress was made in EUV scanner and source technology and EUV resists have achieved acceptable performance levels as well. But issues related to EUV mask inspection and defectivity remain for the most part unanswered. This gap positions EUV masks as the leading risk to the entire technology, and requires a robust solution during the introduction phase of EUVL. In this paper we present results from a EUV mask inspection system. We demonstrate optimal pattern image formation by using illumination shaping, and consider detection of various defect types that represent realistic mask defectivity scenarios. These results demonstrate that DUV-based patterned mask inspection tool can meet the requirements of the pre-production EUV phase, at 32nm half-pitch, and has adequate room to extend to production at the 22nm node.