Catadioptric Projection Objective With Intermediate Images

Abstract

A catadioptric projection objective has a first objective part, defining a first part of the optical axis and imaging an object field to form a first real intermediate image. It also has a second, catadioptric objective part forming a second real intermediate image using the radiation from the first objective part. The second objective part has a concave mirror and defines a second part of the optical axis. A third objective part images the second real intermediate image into the image plane and defines a third part of the optical axis. Folding mirrors deflect the radiation from the object plane towards the concave mirror; and deflect the radiation from the concave mirror towards the image plane. The first part of the optical axis defined by the first objective part is laterally offset from and aligned parallel with the third part of the optical axis.

1 . (canceled) 
     
     
         2 . A lithographic process for making an integrated circuit, comprising:
 projecting, using ultraviolet light, a pattern of a mask onto a semiconductor wafer supporting a layer sensitive to the ultraviolet light, the projecting comprising:
 imaging the pattern to a first intermediate image using a first objective part of a catadioptric projection objective; 
 imaging the first intermediate image to a second intermediate image using a second objective part of the catadioptric projection objective, the second objective part comprising at least two optical elements, the at least two optical elements comprising an active concave mirror; 
 imaging the second intermediate image to a final image at the semiconductor wafer using a third objective part of the catadioptric projection objective, the third objective part comprising:
 a first lens group between the second intermediate image and the semiconductor wafer having a positive refractive power, 
 a second lens group between the first lens group and the semiconductor wafer having negative refractive power, 
 a third lens group between the second lens group and the semiconductor wafer having positive refractive power, 
 a fourth lens group between the third lens group and the semiconductor wafer having positive refractive power, and 
 an aperture stop arranged between the third lens group and the fourth lens group; and 
 
 manipulating the active concave mirror to compensate for imaging errors in the final image at the semiconductor wafer, 
   wherein the imaging defines a marginal ray having a marginal ray height, and wherein the marginal ray height has a point of inflection in the third objective part between the second intermediate image and the aperture stop, and   the catadioptric projection objective has a numerical aperture of greater than 1.25 up to and including 1.35 at the semiconductor wafer.   
     
     
         3 . The process of  claim 2 , wherein the numerical aperture at the semiconductor wafer is 1.35 and the ultraviolet light has a wavelength of 193 nm. 
     
     
         4 . The process of  claim 2 , wherein the pattern is imaged to the first intermediate image by focusing the ultraviolet light solely by refraction. 
     
     
         5 . The process of  claim 4 , wherein the first intermediate image is imaged to the second intermediate image by focusing the ultraviolet light by both refraction and reflection. 
     
     
         6 . The process of  claim 2 , wherein the projecting further comprises providing liquid water in a path of the ultraviolet light between the catadioptric projection objective and the semiconductor wafer. 
     
     
         7 . The process of  claim 2 , wherein the projecting further comprises illuminating the mask with ultraviolet light from an excimer laser. 
     
     
         8 . The process of  claim 7 , wherein the illuminating comprises selecting an illumination mode selected from the group consisting of: annular field illumination, dipole illumination, and quadrupole illumination. 
     
     
         9 . The process of  claim 2 , wherein the projecting further comprises synchronously scanning the mask and the semiconductor wafer relative to the catadioptric projection objective while imaging the pattern on the mask to the semiconductor wafer. 
     
     
         10 . The process of  claim 2 , wherein the catadioptric projection objective further comprises at least one mirror in addition to the concave mirror of the second objective part. 
     
     
         11 . The process of  claim 10 , wherein the at least one additional mirror reflects the ultraviolet light focused by a lens in the first objective part closest to the first intermediate image towards the concave mirror. 
     
     
         12 . The process of  claim 10 , wherein the at least one additional mirror folds an optical axis defined by the catadioptric projection objective. 
     
     
         13 . The process of  claim 2 , wherein manipulating the active concave mirror comprising varying a shape of the mirror to compensate for the imaging errors. 
     
     
         14 . The process of  claim 2 , wherein the second lens group comprises two negative lenses. 
     
     
         15 . The process of  claim 14 , wherein the two negative lenses are consecutive lenses in a path of the ultraviolet light. 
     
     
         16 . The process of  claim 14 , wherein the point of inflection of the marginal ray height is located at a surface of one of the two negative lenses. 
     
     
         17 . The process of  claim 16 , wherein the surface at which the marginal ray height is a faces the other negative lens of the two negative lenses. 
     
     
         18 . The process of  claim 2 , wherein the third lens group comprises two meniscus lenses. 
     
     
         19 . The process of  claim 18 , wherein the two meniscus lenses are adjacent one another in a path of the ultraviolet light. 
     
     
         20 . The process of  claim 2 , wherein the third lens group comprises three aspheric lenses. 
     
     
         21 . The process of  claim 2 , wherein the third lens group comprises at least two aspheric lenses having an aspheric surface facing the mask. 
     
     
         22 . The process of  claim 2 , wherein there are fewer than five lenses in the fourth lens group. 
     
     
         23 . The process of  claim 22 , wherein the fourth lens group comprises a meniscus lens. 
     
     
         24 . The process of  claim 23 , wherein the meniscus lens has an aspheric concave surface. 
     
     
         25 . The process of  claim 2 , wherein the catadioptric projection objective comprises at least one lens having a diameter of greater than 300 mm. 
     
     
         26 . The process of  claim 2 , wherein the pattern is projected to a field at the semiconductor wafer useful for microlithography having a dimension of at least 5 mm. 
     
     
         27 . The process of  claim 26 , wherein the field at the wafer useful for microlithography has a dimension of 26 mm. 
     
     
         28 . The process of  claim 2 , wherein the concave mirror has a diameter, D M , that is smaller than a diameter, D max , of a largest lens of the projection objective. 
     
     
         29 . The process of  claim 2 , wherein D M <0.75 D max . 
     
     
         30 . The process of  claim 2 , wherein the first objective part has a first axial length, AL 1 , measured between the object plane and an intersection of the optical axis with a first folding mirror, the third objective part has a third axial length, AL 3 , measured between the intersection of the optical axis with a second folding mirror downstream in a path of the ultraviolet light from the first folding mirror and the image plane, and AL 1 /AL 3 <0.9. 
     
     
         31 . The process of  claim 2 , wherein a parameter COMP 1 <11, where COMP 1 =D max /(Y′·NA 2 ) in which D max  is a diameter of a largest lens of the projection objective, Y′ is a maximum distance between an image field point and the optical axis, and NA is the numerical aperture at the semiconductor wafer.