| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method of efficiently and effectively focusing radiation onto a target area of a substrate in a lithographic apparatus. <P>SOLUTION: A photon sieve consists of a large number of pinholes, which seem to be appropriately and randomly distributed, instead of rings as diffraction gratings. To obtain a distinct first-order focus, the pinholes must be positioned so that the optical path length from a source via a sensor of the pinholes to the focus is an integral multiple of wavelengths. The diameter of the pinholes is not limited by the width of the corresponding Fresnel zones. This allows pinholes to be positioned in Fresnel zones that are narrower than a limit of production (20 to 40 nm). The photon sieve can be used as a pupil defining element in an illumination system; as a field defining element in an illumination system; as a pupil lens element in a projection lens; as a color correction system in a projection system; or as a transmission diffraction element for EUV. <P>COPYRIGHT: (C)2007,JPO&INPIT |
