Defect repairs for the extreme ultraviolet mask

Extreme ultraviolet (EUV) lithography is a prospective technology for the fabrication of integrated chips with critical dimensions (CDs) under 10-nm. However, since chips with similar CDs have similar defect sizes, one of the most critical problems in extreme ultraviolet lithography (EUVL) is mask defect and repair. Defects cause local areas of undesired absorption, reflectivity, or phase change, which ultimately leads to imperfections in the printed image. For example, phase defects may cause substantial changes in image anomalies with different focuses. In this paper, repair methods such as modified absorber, modified absorber with film adding, modified absorber with multilayer peeling, and vote-taking are compared quantitatively using the scattering matrix method. In cases requiring quick fabrication as well as difficult inspection and repair, the vote-taking method is a more effective way to recover defect patterns.