Lithography apparatus

Abstract

An illumination system for a microlithographic exposure apparatus comprises an adjustable axicon, a variable zoom element, and a multipole illumination mode generating element. By controlling the optical components, the illumination mode can be varied continuously between conventional, annular, and multipole.

1 . A lithography apparatus comprising: 
 a radiation system for supplying a projection beam of radiation;    a first object table provided with a mask holder for holding a mask, and connected to first positioning means;    a second object table provided with a substrate holder for holding a substrate, and connected to second positioning means;    a projection system for imaging an irradiated portion of the mask onto a target portion of the substrate,    wherein said radiation system comprises an illumination system which comprises: 
 an adjustable axicon; and  
 a variable zoom element;  
   characterized by further comprising an adjustable element for generating a multipole illumination mode, whereby at least one spatial parameter of said multipole illumination mode can be continuously varied.    
     
     
         2 . An apparatus according to  claim 1 , further characterized in that the illumination mode is quadrupole.  
     
     
         3 . An apparatus according to  claim 1  or  2 , further characterized in that the multipole mode generating element ( 40 ) comprises one or more blades insertable into the beam path of the illumination system following the axicon and zoom element.  
     
     
         4 . An apparatus according to  claim 3 , further characterized in that said blades comprise a Maltese cross.  
     
     
         5 . An apparatus according to  claim 3 , further characterized in that said blades comprise a pair of triangular blades.  
     
     
         6 . An apparatus according to  claim 3 ,  4  or  5 , further characterized in that the effective width of at least one of said blades is continuously variable.  
     
     
         7 . An apparatus according to  claim 6 , further characterized in that said blade is a composite blade comprising a stack of blades moveable with respect to each other to vary said effective width.  
     
     
         8 . An apparatus according to  claim 1  or  2 , further characterized in that said element for generating a multipole illumination mode comprises a diffractive and/or refractive component.  
     
     
         9 . An apparatus according to  claim 8 , further characterized in that said component comprises at least one pyramidal block.  
     
     
         10 . An apparatus according to  claim 8  or  9 , further characterized in that said component comprises a single pyramidal block.  
     
     
         11 . An apparatus according to  claim 8  or  9 , further characterized in that said component comprises an array of pyramidal blocks.  
     
     
         12 . An apparatus according to  claim 8 , further characterized in that said component comprises at least one wedge-shaped block.  
     
     
         13 . An apparatus according to  claim 8 , further characterized in that said component comprises at least one pair of orthogonally oriented wedge-shaped blocks.  
     
     
         14 . An apparatus according to  claim 13 , further characterized in that the two blocks of the said pair of wedge-shaped blocks are disposed in series in the beam path.  
     
     
         15 . An apparatus according to  claim 13  or  14 , further characterized by comprising an array of said pairs of wedge-shaped blocks.  
     
     
         16 . An apparatus according to  claim 1  or  2 , further characterized in that said element for generating a multipole illumination mode comprises at least one array of lenses or diffractive optical elements.  
     
     
         17 . An apparatus according to  claim 16 , further characterized in that said at least one array comprises an array of Fresnel lens segments.  
     
     
         18 . An apparatus according to  claim 16  or  17 , further characterized by comprising a plurality of arrays, interchangeably positionable in the radiation path.  
     
     
         19 . An apparatus according to any one of the preceding claims, further characterized in that the multipole mode generating element is rotatable about an axis parallel to the principal optical axis of the system.  
     
     
         20 . An apparatus according to any one of the preceding claims, further characterized by further comprising a light pipe having a quadrilateral cross-section.  
     
     
         21 . An apparatus according to  claim 20 , further characterized in that the multipole mode generating element is disposed adjacent to the light pipe entrance.  
     
     
         22 . An apparatus according to  claim 20 , further characterized in that the multipole mode generating element is disposed at an intermediate position along the light pipe.  
     
     
         23 . An apparatus according to  claim 20 ,  21  or  22 , further characterized in that the light pipe comprises a glass, quartz or calcium-fluoride rod.  
     
     
         24 . An apparatus according to any one of  claims 20  to  23 , further characterized in that the principal transverse axes of the multipole mode generating element lie along directions angularly displaced with respect to the principal transverse axes of the light pipe.  
     
     
         25 . An apparatus according to any one of the preceding claims, wherein the radiation system further comprises an excimer laser source, and wherein the adjustable multipole mode generating element is locatable in the collimated beam path of the source.  
     
     
         26 . An apparatus according to any one of the preceding claims, wherein the multipole illumination mode comprises an on-axis pole and at least one off-axis pole.  
     
     
         27 . A device manufacturing method comprising the steps of: 
 providing a substrate which is at least partially covered by a layer of energy-sensitive material;    providing a mask containing a pattern;    using a beam of radiation to project at least part of the mask pattern onto a target area of the layer of energy-sensitive material,    characterized by generating a multipole illumination mode from said radiation before projection, using an adjustable axicon, variable zoom element, and further adjustable element, whereby at least one spatial parameter of said multipole illumination can be continuously varied.    
     
     
         28 . A method according to  claim 27 , further comprising generating an on-axis illumination pole in addition to off-axis poles of the multipole illumination mode.  
     
     
         29 . A device manufactured in accordance with the method of  claim 27  or  28 .