Patterning of EUVL binary etched multilayer mask

Abstract

Recently, development of next generation extremely ultraviolet lithography (EUVL) equipment with high-NA (Numerical Aperture) optics for less than hp10nm node is accelerated. While studying more than 0.45 NA, incident angle distribution of EUV light irradiation to mask becomes larger. It induces degradation of exposure margin to form horizontal line pattern (perpendicular to EUV light direction) because of large mask 3D effect. In order to resolve this issue, we evaluate binary etched multilayer mask structure, unlike conventional stacked absorber structure. As a result of improvement of binary etched multilayer mask process, hp40nm line and space pattern on mask (hp10nm on wafer using 4X optics) is demonstrated. This result suggests the capability of high-NA EUVL with 6inch and 4X optics with new mask structure.