Asahi Glass Company (AGC) has been developing the extreme ultra violet (EUV) lithography mask blank and
polished substrate since 2003, including the developments of all essential materials and processes: the low thermal
expansion material (LTEM), the material developments of the reflective, capping and absorber films, the process
developments of the substrate polishing, cleaning, film deposition and resist film coating processes.
In this paper, we present the current development status of the full-stack EUV mask blank and polished substrate which
are the most suitable for the EUV lithography process development with EUV pre-production exposure tools. We report
the development progress of the reflective multilayer-coated LTEM substrate by showing its critical performances with
those of 2010 achievements, which include the substrate flatness, the EUV optical properties of the Mo/Si reflective
layers and the defect of LTEM substrate and reflective layer. The performances of the Ta-based absorber and the resist
films are explained as well to show the readiness of the EUV mask blank suitable for various kinds of process
developments of the EUV lithography.