Mask handling apparatus, lithographic projection apparatus, device manufacturing method and device manufactured thereby

Abstract

In a lithographic projection apparatus, an object such as a mask is shielded from stray particles by a particle shield using electromagnetic fields. The fields may be a uniform electric field, a non-uniform electric field or an optical breeze. The particle shield means are fixed to the mask holder rather than the mask.

1 . A lithographic projection apparatus comprising: 
 a radiation system for supplying a projection beam of radiation;    a support structure for supporting patterning means, the patterning means serving to pattern the projection beam according to a devised pattern;    a substrate table for holding a substrate; and    a projection system for projecting the patterned beam onto a target portion of the substrate; characterized by 
 particle shield means for generating an electromagnetic field so as to prevent particles to become incident on an object to be shielded.  
   
     
     
         2 . An apparatus according to  claim 1 , wherein said particle shield means is configured and arranged so as to deflect particles approaching the object to be shielded.  
     
     
         3 . An apparatus according to  claim 1  or  2 , wherein said particle shield means comprises an electric field.  
     
     
         4 . An apparatus according to  claim 1 ,  2  or  3 , wherein said particle shield means is adapted to generate said electric field in the vicinity of said object to be shielded.  
     
     
         5 . Apparatus according to any one of the preceding claims, wherein said particle shield means is adapted to generate a non-uniform electric field.  
     
     
         6 . Apparatus according to  claim 5 , wherein said particle shield means comprises an elongate charged member.  
     
     
         7 . Apparatus according to any one of the preceding claims, wherein said particle shield means is adapted to generate a substantially uniform electric field.  
     
     
         8 . Apparatus according to  claim 7 , wherein said particle shield means comprises a pair of conductive plates arranged substantially parallel to each other on either side of a region adjacent said object to be shielded and means for establishing a potential difference between said pair of conductive plates.  
     
     
         9 . Apparatus according to any one of the preceding claims, wherein said particle shield means comprises a grid or an array of electrodes.  
     
     
         10 . Apparatus according to  claim 9 , wherein said grid or array is arranged substantially parallel to a surface to be shielded of said object to be shielded.  
     
     
         11 . Apparatus according to any one of the preceding claims, wherein said particle shield means comprising an electrostatic getterer plate and means for charging said electrostatic getterer plate to a potential so as to generate an electric field to attract particles.  
     
     
         12 . Apparatus according to any one of the preceding claims, wherein said particle shield means are configured and arranged to transport particles out of a space within said apparatus.  
     
     
         13 . Apparatus according to any one of the preceding claims, wherein said particle shield means includes at least one particle trap, said particle trap comprising a recess in a surface, said recess being shaped so that it is easier for a particle to enter said recess than to exit said recess.  
     
     
         14 . Apparatus according to any one of the preceding claims, wherein said particle shield means comprises a radiation source arranged to generate a beam of radiation.  
     
     
         15 . Apparatus according to  claim 14 , wherein said radiation source is adapted to generate an electromagnetic beam effective as an optical breeze to deflect particles by momentum transfer.  
     
     
         16 . Apparatus according to  claim 14  or  15 , wherein said radiation source is adapted to generate a beam of radiation capable of ionizing particles.  
     
     
         17 . Apparatus according to any one of the preceding claims, wherein said particle shield means comprises means for charging said object to be shielded to a bias potential relative to its surroundings.  
     
     
         18 . Apparatus according to anyone of the preceding claims, wherein said support structure comprises a mask table for holding a mask.  
     
     
         19 . Apparatus according to  claim 18 , wherein said object to be shielded is a mask held on said mask table.  
     
     
         20 . Apparatus according to any one of  claims 1  to  18 , wherein said object to be shielded is a mirror or other element comprised in the illumination or projection systems.  
     
     
         21 . Apparatus according to  claim 18 , further comprising a mask handling part for transferring said mask to said mask table, and wherein said mask handling part comprises said particle shield means for shielding said mask.  
     
     
         22 . Apparatus according to any one of the preceding claims, further comprising a substrate handling part for transferring said substrate to said substrate table, and wherein said substrate handling part comprises said particle shield means for shielding said substrate.  
     
     
         23 . A device manufacturing method comprising the steps of: 
 providing a substrate which is at least partially covered by a layer of radiation sensitive material to said second object table;    providing a projection beam of radiation using a radiation system;    using patterning means to endow the projection beam with a pattern in its cross section;    projecting the patterned beam of radiation onto a target portion of the layer of radiation sensitive material; characterized by the step of: 
 generating an electromagnetic field so as to prevent particles to become incident on an object to be shielded.  
   
     
     
         24 . A device manufactured in accordance with the method of  claim 23 .  
     
     
         25 . A mask handling device comprising: 
 a chamber for enclosing a mask during handling, transportation or storage thereof; and    a particle shield for preventing or reducing the contamination of at least the patterned surface of said mask by particles.    
     
     
         26 . A mask handling device according to  claim 25 , wherein said particle shield comprises particle shield means for generating an electromagnetic field so as to prevent particles to become incident on at least the patterned surface of said mask.  
     
     
         27 . A mask handling device according to  claim 26 , wherein said particle shield means comprises a grid or array of electrodes.  
     
     
         28 . A mask handling device according to claims  26  or  27 , wherein said particle shield comprises a heater for maintaining said mask at a temperature greater than its surroundings.  
     
     
         29 . A mask handling device according to  claim 26 ,  27  or  28 , wherein said particle shield comprises a plate disposed proximate said mask and a cooler for maintaining said plate at a temperature less than the temperature of said mask.  
     
     
         30 . A mask handling device according to any one of  claims 26  to  29 , wherein said device is a mask storage box.