Application of X-ray mask fabrication technologies to high resolution, large diameter Ta Fresnel zone plates

High-resolution and large diameter condenser Fresnel zone plates were fabricated in a 0.35-mu m-thick Ta layer on an SiN membrane. A newly developed conversion algorithm was applied where sub-field length and position are randamized in order to suppress the evolution of small figures at pattern divided parts such as subfield boundaries in the conventional conversion algorithm. A single layer resist system was adopted to write large diameter, ultra-fine, dense ring patterns. FZPs with the outer-most linewidth of 50 nm was successfully fabricated by applying the subtractive x-ray mask fabrication process.