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The mask pattern is created on the multilayer reflection mirror in the EUV lithography. This is the origin of the issues such as the absorber shadowing (mask-3D) and contrast loss at high-NA tool. To solve these issues, this paper presents conceptual discussions on a new configuration which employs rotating mirror (precession beam) to illuminate the mask from normal direction with small tilt angle matches to the numerical aperture: 8.3 deg at 0.55 NA and 11.3 deg at 0.71 NA, both angles are acceptable for multi-layer mirror of the mask. Unlike current EUV machine design, all optical components are axial symmetric and aligned on axis (in-line), and thus form a plane-parallel resonator configuration. xand y-magnifications are same 4x, and full-field 33 mm x 26 mm may be possible at high-NA as high as 0.71. Annular slit at the back focal plane acts as Fourier spatial filter, which removes 3D components, thus resulting image becomes longitudinally projected mask pattern without shadows. The system becomes a both-side telecentric camera, providing long depth-of-focus and high contrast image. As the objective mirror, Schwarzschild objective or Wolter telescope will be a suitable candidate. Wolter telescope is axisymmetric and lighter than conventional solid concave mirror, therefore, a larger diameter mirror can be fabricated in high precession. After the objective mirror, all diffractions have the same angles to the axis (cone beam) including the illumination beam. A new concept “the generalized interference lithography” will be introduced as the working principle of pattern writing on the wafer.
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