Method For Adjusting A Projection Objective

Abstract

A projection objective having a number of adjustable optical elements is optimized with respect to a number of aberrations by specifying a set of parameters describing imaging properties of the objective, each parameter in the set having an absolute value at each of a plurality of field points in an image plane of the projection objective. At least one of the optical elements is adjusted such that for each of the parameters in the set, the field maximum of its absolute value is minimized.

What is claimed is: 
     
         1 - 19 . (canceled) 
     
     
         20 . A microlithography projection exposure machine, comprising:
 an illumination device for illuminating a reticle;   a projection objective comprising a plurality of optical elements for projecting an image of the reticle onto a substrate in an image field at an image plane of the projection objective;   a plurality of manipulators each configured to move either the reticle or a corresponding one of the optical elements of the projection objective; and   a control unit configured to adjust the projection exposure machine between different configurations by causing one or more of the manipulators to adjust a position of the reticle and/or at least one of the optical elements of the projection objective, the different configurations comprising an initial configuration and a second configuration,   wherein, in the initial configuration, a maximum value at least one field point among a plurality of different field points in the image field for an absolute value of a parameter indicative of a performance of the projection exposure machine exceeds a specified field maximum value, the parameter being a lithographic process parameter or an image-forming parameter of the projection objective, and   in the second configuration, a largest absolute value for every one of the plurality of different field points is less than the specified field maximum value.   
     
     
         21 . The microlithography projection exposure machine of  claim 20 , wherein the field at the image plane is defined by a scanner slit. 
     
     
         22 . The microlithography projection exposure machine of  claim 21 , wherein the plurality of different field points lie along a line oriented in a scanning direction of the projection exposure machine. 
     
     
         23 . The microlithography projection exposure machine of  claim 20 , wherein field maximum values are specified for more than one parameter indicative of the performance of the projection exposure machine. 
     
     
         24 . The microlithography projection exposure machine of  claim 20 , wherein the lithographic process parameter is related to the image-forming parameter. 
     
     
         25 . The microlithography projection exposure machine of  claim 20 , wherein the image-forming parameter of the projection objective is selected from the group consisting of: individual Zernike coefficients describing wave aberrations of an objective pupil of the projection objective; a linear combinations of Zernike coefficients; and an average of Zernike coefficients over a plurality of the different points. 
     
     
         26 . The microlithography projection exposure machine of  claim 20 , wherein the lithographic process parameter is selected from the group consisting of a horizontal offset of a structure from its ideal position and a deviation from an ideal line width. 
     
     
         27 . The microlithography projection exposure machine of  claim 20 , wherein the parameter indicative of a performance of the projection exposure machine describes a centrable aberration, and the manipulators are configured to tilt the reticle of the projection objective to adjust for the centrable aberration. 
     
     
         28 . The microlithography projection exposure machine of  claim 27 , wherein the manipulators are configured to:
 (i) displace at least one of the optical elements in a direction perpendicular to an optical axis of the projection objective, and   (ii) tilt at least one of the optical elements in a direction perpendicular to said optical axis of the projection objective.   
     
     
         29 . The microlithography projection exposure machine of  claim 28 , wherein the parameter indicative of a performance of the projection exposure machine describes a tunable aberration, and the manipulators are configured to adjust at least one of the optical elements to adjust for the tunable aberration and the centrable aberration jointly. 
     
     
         30 . The microlithography projection exposure machine of  claim 29 , wherein the manipulators are configured to:
 (i) displace at least one of the optical elements in a direction along the optical axis of the projection objective;   (ii) change a wavelength of illumination of the projection exposure machine;   (iii) change a temperature within the projection exposure machine;   (iv) change an air pressure within the projection exposure machine, and   (v) change a composition of a purge gas surrounding the optical elements.   
     
     
         31 . The microlithography projection exposure machine of  claim 20 , wherein the control unit is configured to adjust the projection exposure machine according to a nonlinear method. 
     
     
         32 . The microlithography projection exposure machine of  claim 31 , wherein the nonlinear method comprises a nonlinear optimization of the parameter values. 
     
     
         33 . The microlithography projection exposure machine of  claim 32 , wherein the nonlinear optimization comprises a nonlinear min-max optimization.