| 摘要 |
The projection objective lens for short waves, preferably less than 100 nm has six mirrors (S1-6). The image side numerical aperture (NA) is more than 0.15. The wafer etc. to be next illuminated is so arranged on next arriving mirror that the image side, optical free work spacing correspond at least to the used diameter of the mirror nearest to the wafer. Alternatively the optical free work spacing is at least the sum of one third of the used diameter of the mirror and a length between 20 and 30mm and/or the image side optical free working spacing is at least 50mm, preferably 60mm. Independent claims are included for projection illumination installation and use of the objective lens in chip manufacture.
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