| 摘要 |
A catadioptric projection objective has a plurality of optical elements arranged along an optical axis to image a pattern from an object field in an object surface of the objective to an image field in an image surface region of the objective at an image-side numerical aperture NA =1.35 with electromagnetic radiation defining an operating wavelength ?. The optical elements form a first objective part configured to image the pattern from the object surface into a first intermediate image, a second objective part configured to image the first intermediate image into a second intermediate image, the second objective part including a concave mirror having a reflective mirror surface positioned at or close to a pupil surface; and a third objective part configured to image the second intermediate image into the image surface. A first deflecting mirror is arranged to deflect radiation from the object surface towards the concave mirror, and a second deflecting mirror is arranged to deflect radiation from the concave mirror towards the image surface such that the image surface is parallel to the object surface. The projection objective has an immersion lens group having a convex object-side entry surface bounding at a gas or vacuum and an image-side exit surface in contact with an immersion liquid in operation. The immersion lens group is at least partly made of a high-index material with refractive index n = 1.6 at the operating wavelength. |
