FABRICATION AND CHARACTERIZATION OF HIGH-FLATNESS MESA-ETCHED SILICON-NITRIDE X-RAY MASKS

To realize a technology for x-ray nanolithography (< 100 nm features), which is compatible with manufacturing, a number of mask design requirements must be met that are unrelated to patterning, repair, and alignment. These include high-flatness membranes and support structures so that mask-wafer gaps less than 10-mu-m can be achieved without risk of damage, and a rigid mask frame to avoid problems of distortion during handling. The membrane material should be compatible with semiconductor-processing, possess high strength, be radiation hard, and be transparent to light for alignment purposes. Details of a mask architecture that meets these requirements will be described.