Charged-particle-beam microlithography apparatus and methods for exposing a segmented reticle

Abstract

Charged-particle-beam (CPB) microlithography apparatus and methods are disclosed that employ a segmented reticle in which the pattern defined by the reticle is divided into multiple subfields, and each subfield is subdivided into multiple subregions each constituting a respective “group” of subregions. During exposure of the pattern from the reticle to a sensitive substrate using a charged particle beam, a charged-particle illumination beam is directed in sequence to each of the groups. At each group, the illumination beam is directed to expose the respective subregions in the group in a predetermined order before directing the illumination beam to a subsequent group. Direction of the illumination from one group to the next can be performed using a first deflector, and direction of the illumination beam from one subregion to the next in a group can be performed using a second deflector.

What is claimed is:  
     
         1 . In a method for performing charged-particle-beam (CPB) microlithography in which a region on a pattern-defining reticle, divided into multiple subfields, is illuminated with an illumination beam to produce an image of the illuminated region as projected on a sensitive substrate, a method for exposing the subfields, comprising: 
 (a) dividing each of the subfields into respective groups of multiple subregions such that each subfield comprises at least two respective subregions;    (b) directing an illumination beam in sequence to each of the groups; and    (c) at each group, directing the illumination beam to expose the respective subregions in the group in a predetermined order before directing the illumination beam to a subsequent group.    
     
     
         2 . The method of  claim 1 , wherein the subregions in each group are exposed in the predetermined order that is identical from one group to the next in the sequence.  
     
     
         3 . The method of  claim 1 , wherein the subregions in each group are exposed in the predetermined order that is identical for every other group in the sequence.  
     
     
         4 . The method of  claim 1 , wherein step (b) is performed using a first deflector, and step (c) is performed using a second deflector.  
     
     
         5 . The method of  claim 4 , wherein the first and second deflectors are provided in an illumination-optical system.  
     
     
         6 . A charged-particle-beam (CPB) microlithographic exposure apparatus that exposes a pattern, defined by a segmented reticle divided into multiple subfields each defining a respective portion of the pattern, onto a sensitive substrate using a charged particle beam so as to form respective transfer images of the subfields on the sensitive substrate, the apparatus comprising: 
 an illumination-optical system situated and configured to direct a charged-particle illumination beam from a source to the segmented reticle, in which reticle each subfield comprises a respective group of multiple subregions;    a first deflector situated and configured to deflect the illumination beam from one group to the next on the reticle in a predetermined exposure sequence;    a second deflector situated and configured to deflect the illumination beam, within a group selected by the first deflector, to expose the respective subregions in the selected group in a predetermined order before the illumination beam is deflected to a subsequent group; and    a projection-optical system situated and configured to form a respective image, on a sensitive substrate, of each subregion illuminated by the illumination beam.    
     
     
         7 . The apparatus of  claim 6 , further comprising a controller connected to the first and second deflectors and configured to energize the first deflector in the predetermined exposure sequence and to energize the second deflector in the predetermined order.  
     
     
         8 . The apparatus of  claim 6 , further comprising a third deflector situated between the reticle and the substrate, the third deflector being configured to direct, in synchrony with the second deflector, formation of the respective image on a corresponding predetermined location on the sensitive substrate.  
     
     
         9 . A method for manufacturing a microelectronic device, comprising the steps of: 
 (a) preparing a wafer;    (b) processing the wafer; and    (c) assembling devices formed on the wafer during steps (a) and (b), wherein step (b) comprises a method for performing microlithography as recited in  claim 1 .    
     
     
         10 . A microelectronic device produced by the method of  claim 9 .  
     
     
         11 . A microelectronic-device fabrication process, comprising the steps of: 
 (a) preparing a wafer;    (b) processing the wafer; and    (c) assembling microelectronic devices on the wafer during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the wafer; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a charged-particle-beam microlithography apparatus as recited in  claim 6;  and using the charged-particle-beam microlithography apparatus to expose the resist with the pattern defined on the reticle.