Total quality on EUV mask blanks have to be improved toward future volume production. In this paper, progress in EUV blank development and improvement in flatness, bow and ML blank defects as critical issues on EUV blanks were reported. Steadily progress in flatness improvement was made in the past five years by improving polishing processes. A LTE substrate with a high flatness of 78 nm PV in 142 mm square area was achieved in average. Annealing process was developed to make small bow of less than 600 nm after ML coating. It was confirmed that annealed ML blank has stable performance in bow and centroid wavelength values through mask making process. Small bow of less than 300 nm was successfully demonstrated using annealing process and a CrN back side film with high compressive stress. Low defects of 0.05 defects/cm 2 at 70 nm SiO 2 sensitivity inspected by a Lasertec M1350 was demonstrated on a multilayer (ML) blank with a LTE substrate as best. Small defects over 50 nm in a M7360 were effectively reduced by improvement of polishing process consisting of local polish, touch polish and cleaning.

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Embedded phase-shift mask (EPSM) has an advantage in comparison with several other phase-shifting mask approaches because of its simple structure and fabrication process. We tried to modify MoSi-based EPSM blanks by re-examining the material and by optimizing sputtering condition in order to produce more useful EPSM blanks for Deep UV lithography technology. New MoSi-based EPSM blanks for which Nitrogen gas is used as the reactive sputtering gas has been developed. And it has been confirmed that the New MoSi-based EPSM(MoSi-N) blanks are superior to HOYA previously developed one (MoSi-ON) in chemical durability, manufacturing stability and Dry Etching property.

A concentric circle pattern with an accuracy of 0.1 mu m and a circle pattern of diameter 60 mm have been fabricated under a fixed electron beam. Using the newly developed specimen stage, a positioning accuracy of 0.01 mu m of the linear stage and a rotation error of 0.05 mu mp-p of the rotary stage have also been obtained. However, there is the problem of patterning errors due to the reactive magnetic field of the eddy current on the rotary stage. A finite-element method magnetic-field analysis has been applied to determine the level of patterning errors. As a result of the simulation, the patterning errors amount to 1*10-5 mu m under a rotation of 1000 rpm using a semiconductive specimen holder on the rotary stage, and 470 mu m using an aluminum specimen holder. In practice 100 k Omega cm SiC ceramics are used for the specimen holder.