Projection-exposure methods and apparatus exhibiting increased throughput

Abstract

Projection-exposure apparatus and methods are disclosed that exhibit increased throughput by providing improved schemes by which the reticle stage and wafer stage move to accomplish exposure. Portions of a die pattern on a “pattern original” (e.g., reticle) are sequentially illuminated by an energy beam (e.g., beam of electromagnetic radiation or charged particles). The energy beam passes through the pattern portions and forms a demagnified image on a substrate through a projection-optical system. While moving the pattern original and the substrate, the entire die pattern is sequentially illuminated according to an exposure order, and the die pattern is demagnifyingly transferred to the substrate on which the images of the illuminated pattern portions are stitched together. When transferring and exposing the die pattern to multiple locations on the substrate, the exposure order is reversed after exposing each die pattern.

What is claimed is:  
     
         1 . A method for projection-exposing a die pattern, defined by a pattern original and comprising multiple pattern portions for individual exposure, onto multiple locations on a substrate, the method comprising: 
 (a) directing an energy beam to impinge on a pattern portion of the die pattern defined by the pattern original and form a patterned beam from the energy beam passing through and propagating downstream of the illuminated pattern portion, the patterned beam carrying an image of the illuminated pattern portion, and directing the patterned beam to form the image of the illuminated pattern portion on the substrate;    (b) repeating step (a), in a first exposure order, for each of the remaining pattern portions of the die pattern so as to expose an image, comprising stitched-together images of the pattern portions, of the die pattern at a first location on the substrate; and    (c) repeating steps (a) and (b), wherein step (b) is performed in a second exposure order different from the first exposure order, so as to expose an image of the die pattern at a second location on the substrate.    
     
     
         2 . The method of    claim 1   , wherein, in step (a), the pattern original is mounted on a first movable stage and the substrate is mounted on a second movable stage axially displaced from the first movable stage.  
     
     
         3 . The method of    claim 2   , wherein, in steps (a) and (b), the first and second stages synchronously move the pattern original and substrate, respectively, to scanningly expose each pattern portion.  
     
     
         4 . The method of    claim 2   , wherein the first and second stages step the pattern original and substrate, respectively, after exposing each pattern portion so as to position the pattern original and substrate, respectively, for exposure of the subsequent pattern portion.  
     
     
         5 . The method of    claim 1   , wherein, in step (a), the image of the illuminated pattern portion formed on the substrate is a demagnified image.  
     
     
         6 . The method of    claim 1   , wherein the second exposure order is reversed relative to the first exposure order.  
     
     
         7 . The method of    claim 1   , wherein the energy beam is an electron beam.  
     
     
         8 . The method of    claim 1   , wherein the energy beam is a beam of electromagnetic radiation.  
     
     
         9 . The method of    claim 1   , wherein: 
 the die pattern is divided into multiple pattern portions arranged on the pattern original; and    each pattern portion is sequentially projected, as an individual exposure unit, and exposed onto the substrate using the energy beam, the pattern original being stepped to a subsequent pattern portion after exposing each pattern portion of the die pattern.    
     
     
         10 . The method of    claim 9   , wherein: 
 the pattern portions of the die pattern are arranged in a two-dimensional array on the pattern original; and    the first exposure order includes stepping the pattern original and the substrate in two dimensions so as to expose the die pattern at the first location on the substrate.    
     
     
         11 . The method of    claim 1   , wherein, between steps (b) and (c), the pattern original remains stationary while the substrate is moved to position the substrate to begin exposure of the die pattern at the second location.  
     
     
         12 . The method of    claim 1   , wherein: 
 the energy beam impinging on each pattern portion of the pattern original passes through an illumination optical system having a field of view;    the die pattern on the pattern original is divided into multiple pattern portions each falling within the field of view; and    each pattern portion is sequentially projected, within the field of view, and exposed onto the substrate using the energy beam, the pattern original being stepped to a subsequent pattern portion and the substrate being stepped to a subsequent exposure location for the subsequent pattern portion, after exposing each pattern portion of the die pattern.    
     
     
         13 . The method of    claim 1   , wherein: 
 the energy beam impinging on each pattern portion of the pattern original passes through an optical system having a field of view;    the die pattern on the pattern original is divided into multiple pattern portions each having a dimension greater than a corresponding dimension of the field of view;    the pattern original and the substrate are synchronously scanned during exposure of each pattern portion; and    the pattern original and the substrate are stepped during each transition from exposure of one pattern portion to exposure of a subsequent pattern portion of the die pattern.    
     
     
         14 . The method of    claim 13   , wherein, in the second exposure order: 
 the pattern portions of the die are exposed in an order that is opposite an order in which the pattern portions are exposed in the first exposure order: and    scanning exposure of each pattern portion is in a direction opposite a direction in which scanning exposure was performed of the corresponding pattern portion in the first exposure order.    
     
     
         15 . The method of    claim 1   , wherein, in step (a), the energy beam passes through an illumination optical system that directs the energy beam to impinge on each pattern portion, and the patterned beam passes through a projection-optical system that directs the patterned beam to corresponding exposure regions on the substrate.  
     
     
         16 . The method of    claim 15   , wherein: 
 in step (a), the pattern original is mounted on a first movable stage and the substrate is mounted on a second movable stage axially displaced from the first movable stage;    the first and second stages synchronously move the pattern original and substrate, respectively, as required to expose each pattern portion;    the energy beam is a charged particle beam;    the illumination-optical system directs the charged particle beam and the projection-optical system directs the patterned beam and forms an image of the illuminated pattern portion by one or more of electrical and magnetic action that deflects the charged particle beam; and    deflection of the charged particle beam on the pattern original and deflection of the patterned beam on the substrate are performed in coordination with movement of the first and second movable stages.    
     
     
         17 . The method of    claim 1   , wherein: 
 the die pattern is divided into multiple pattern portions arranged on the pattern original; and    whenever at least one pattern portion is projected outside the substrate, actual exposure of the pattern portion is omitted.    
     
     
         18 . A projection-exposure apparatus, comprising; 
 (a) a movable substrate stage on which a substrate is mounted for exposure;    (b) a movable pattern-original stage on which a pattern original is mounted for exposure, the pattern original defining a die pattern to be transferred to multiple locations on the substrate, the die pattern being divided into multiple pattern portions, the pattern-original stage being situated axially upstream of the substrate stage;    (c) an illumination optical system situated axially upstream of the pattern-original stage, the illumination-optical system having a field of view and being operable to direct an energy beam so as to illuminate a pattern portion aligned with the field of view;    (d) a projection-optical system situated between the pattern-original stage and the substrate stage, the projection-optical system being operable to form, from the energy beam passing through an illuminated pattern portion, a patterned beam that forms a demagnified image of the illuminate pattern portion on a corresponding exposure region on the substrate; and    (e) a controller connected to and operable to controllably operate the illumination-optical system, the pattern-original stage, the projection-optical system, and the substrate stage, the controller being programmed with a map providing the controller with operability to move the pattern-original stage and the substrate stage in at least one of a scanning and step-wise manner so as to sequentially illuminate the pattern portions on the pattern original and demagnifyingly project the pattern portions onto corresponding exposure regions of the substrate according to an exposure order while stitching together images of the pattern portions on the exposure regions to form the die pattern on the substrate, the map also providing the controller with operability to change the exposure order of the pattern portions with every sequentially new die being exposed on the substrate.    
     
     
         19 . The apparatus of    claim 18   , wherein the exposure order is reversed with every sequentially new die being exposed on the substrate.  
     
     
         20 . The apparatus of    claim 18   , wherein; 
 the energy beam is a charged particle beam;    each of the illumination-optical system and the projection-optical system comprises a respective deflector and respective lens that deflect and form an image, respectively, of the charged particle beam by at least one of electric and magnetic action; and    deflection of the charged particle beam to illuminate a pattern portion on the pattern original and deflection of the patterned beam on the substrate are performed in coordination with movement of the substrate stage and the pattern-original stage.    
     
     
         21 . The apparatus of    claim 19   , wherein: 
 the die pattern is divided into multiple pattern portions wider than the field of view, the pattern portions being arranged on the pattern original;    the pattern-original stage and the substrate stage are operable to scanningly move the pattern original and the substrate, respectively, synchronously during each exposure of a pattern portion, and to steppingly move the pattern-original and the substrate, respectively, during a transition from exposure of a previous pattern portion to a subsequent pattern portion; and    upon completion of exposure of each die on the substrate, the exposure order of each pattern portion of the die pattern being reversed and the scanning direction of each pattern portion of the die pattern being reversed.    
     
     
         22 . The apparatus of    claim 18   , wherein: 
 the die pattern is divided into multiple pattern portions arranged on the pattern original; and    when at least one pattern portion is projected outside the substrate, actual exposure of the pattern portion is omitted.