JP2014199461A5 - - Google Patents

Description

Each projection objective described here has a high NA image side end where projection radiation emerges from the projection objective at the exit plane ES, which is a planar substrate disposed on the image plane IS. A plane is preferred to allow a uniform distance between the surface and the exit surface. The lens that forms the exit surface ES closest to the image plane is referred to herein as the “final lens” LL. Preferably, the final lens is a plano-convex positive lens having a curved entrance surface ENS and a planar exit surface, which is curved spherically in most embodiments. For the purpose of obtaining a high NA, it has been found advantageous to configure the final lens so that the large refractive power provided by the curved entrance surface ENS is located as close as possible to the image plane. Furthermore, it is clear that a large curvature of the entrance surface ENS of the final lens LL, that is, a small radius of curvature is desirable. T _LL is the thickness of the final lens on the optical axis (that is, the axial distance between the entrance surface ENS and the exit surface ES measured along the optical axis), and R _LL is the object-side apex radius of the final lens ( That is, the radius of the incident surface ENS), and DIA _LL is the optical free diameter of the incident surface of the final lens, the parameters LL1 = T _LL / R _LL and LL2 = DIA _LL / R _LL are preferably within a certain range. Should enter. In particular, it has been found advantageous if the condition 0.46 ≦ LL1 ≦ 0.69 applies to LL1. Since the parameter LL1 is 1 for a hemispherical lens whose center of curvature of the entrance surface coincides with the exit surface, the condition regarding LL1 is that the center of curvature of the curved entrance surface exists outside the final lens, particularly beyond the image plane. This indicates that a non-hemispheric final lens is preferred.

Alternately or additionally, the condition 1.15 ≦ LL2 ≦ 1.67 should preferably apply to LL2. The respective values for LL1 and LL2 are shown in Table 18.
If at least one of the above conditions is true, a large positive refractive power provided by the curved entrance surface of the final lens is provided near the image surface, so that a large image-side numerical aperture NA, in particular NA> 1.1. Or NA> 1.2, and NA = 1.3 or NA = 1.35 can be obtained.

[Table 18]

Claims (1)

A catadioptric projection objective for imaging a pattern provided on the object plane of the projection objective on the image plane of the projection objective,
A first refractive objective part for forming a pattern provided on the object plane into a first intermediate image;
A second objective part for imaging the first intermediate image into a second intermediate image;
A third refractive objective part for imaging the second intermediate image on the image plane;
The second objective part has a first concave mirror having a first continuous mirror surface and a second concave mirror having a second continuous mirror surface;
A pupil plane is formed between the object plane and the first intermediate image, between the first and second intermediate images, and between the second intermediate image and the image plane;
All concave mirrors are placed optically away from the pupil plane,
The first objective part has N1 _AS aspherical lenses of a first number;
The third objective part has N3 _AS aspherical lenses of a second number;
Aspheric lens ratio ASR = N1 _AS / N3 _AS is smaller than 1,
Catadioptric projection objective with an image-side numerical aperture NA greater than 1.2.