| 摘要 |
<p>Disclosed is apparatus, exemplarily semiconductor X-ray lithography apparatus, that comprises a novel projection system. In preferred embodiments the projection system is adapted for use with radiation (12') of wavelength below about 30 nm. The system comprises four or more mirrors (21-24) that form a finite conjugate "optical" system that is telecentric at the short conjugate. The mirrors can be selected such that an essentially flat, diffraction limited image is formed. The image field can be two-dimensional, exemplarily a 10 x 10 mm square, and the resolution over the image field can be higher than 0.25 mu m. Exemplarily, the "optical" system comprises, from long to short conjugate, a convex (21), a concave (22), a convex (23), and a concave mirror (24), with at least two of the mirrors being aspherics. The radius absolute values of the four mirrors are, in the above order and as a fraction of the system focal length, 2.20, 2.59, 2.51, and 2.13 all to within +/- 5%. Equivalently, the radii of the four mirrors are, in the same order, in the ratio of 1.00, 1.18, 1.14, and 0.97, all to within +/- 5%. The axial separations, in the same order and as a fraction of the system focal length, are 1.45, 1.47, 1.10, and 1.21, the last being the separation between the second concave mirror and the image, all within +/- 10%.</p> |
