Electron beam lithography system having improved electron gun

Abstract

An electron beam lithography system has an electron gun including at least one laser that is operable in a first mode to generate electrons for lithography. The electron beam lithography system is operable in a second mode to regenerate the photocathode of the electron gun by application of the laser. The photocathode includes a layer of cesium telluride.

What is claimed is:  
     
         1 . An electron beam lithography system, comprising: 
 an electron column for focusing said electron beam; and    an electron gun, said electron gun comprising: 
 at least one laser; and  
 a photocathode substantially comprising cesium telluride and adapted to be activated to generate electrons by said at least one laser and to be regenerated by said at least one laser.  
   
     
     
         2 . An electron beam lithography system in accordance with  claim 1 , wherein said photocathode comprises a cesium telluride film on a substrate.  
     
     
         3 . An electron beam lithography system in accordance with  claim 2 , said photocathode including a metallic film interposed between said cesium telluride layer and said substrate.  
     
     
         4 . An electron beam lithography system in accordance with  claim 2 , including means for applying a current in a plane of said cesium telluride layer.  
     
     
         5 . A method for electron beam lithography, comprising: 
 applying at least one laser in a first mode to a cesium telluride photocathode for generating electrons; and    applying said at least one laser to said cesium telluride photocathode in a second mode to regenerate said cesium telluride photocathode.    
     
     
         6 . A method according to  claim 5 , wherein in said first mode, said laser is applied at a power density of approximately 10 4  Watts per square centimeter.  
     
     
         7 . A method in accordance with  claim 6 , wherein in said second mode, said at least one laser is applied at a power density in the range substantially comprising 10 4 -10 6  Watts per square centimeter.  
     
     
         8 . A method in accordance with  claim 6 , wherein in said second mode, said at least one laser is applied to raise a temperature of said cesium telluride photocathode in the range substantially comprising 20-200 C above room temperature.  
     
     
         9 . A method in accordance with  claim 8 , a wavelength of said laser comprising approximately 257 nanometers.  
     
     
         10 . An electron gun, comprising: 
 at least one laser; and    a photocathode adapted to be activated to generate electrons by said at least one laser and to be regenerated by said at least one laser    
     
     
         11 . An electron gun in accordance with  claim 10 , wherein said photocathode comprises a cesium telluride film on a substrate.  
     
     
         12 . An electron gun in accordance with  claim 11 , said photocathode including a metallic film interposed between said cesium telluride layer and said substrate.  
     
     
         13 . A method, comprising: 
 providing at least one laser; and    providing a photocathode adapted to be activated to generate electrons by said at least one laser and to be regenerated by said at least one laser.    
     
     
         14 . An method in accordance with  claim 13 , wherein said photocathode comprises a cesium telluride film on a substrate.  
     
     
         15 . An method in accordance with  claim 14 , said photocathode including a metallic film interposed between said cesium telluride layer and said substrate.  
     
     
         16 . An electron beam lithography system, comprising: 
 an electron column; and    an electron gun;    wherein said electron gun is adapted to apply at least one laser in a first mode to a cesium telluride photocathode for generating electrons; and    said electron gun is adapted to apply said at least one laser to said cesium telluride photocathode in a second mode to regenerate said cesium telluride photocathode.    
     
     
         17 . An electron beam lithography system according to  claim 16 , wherein in said first mode, said at least one laser is applied at a power density of approximately 10 4  Watts per square centimeter.  
     
     
         18 . An electron beam lithography system in accordance with  claim 16 , wherein in said second mode, said at least one laser is applied at a power density in the range substantially comprising 10 4 -10 6  Watts per square centimeter.  
     
     
         19 . An electron beam lithography system in accordance with  claim 16 , wherein in said second mode, said at least one laser is applied to raise a temperature of said cesium telluride photocathode in the range substantially comprising 20-200 C above room temperature.  
     
     
         20 . An electron beam lithography system in accordance with  claim 19 , a wavelength of said laser comprising approximately 257 nanometers.  
     
     
         21 . A controller for an electron beam lithography system, said controller adapted to control application of at least one laser to a photocathode in a first mode for generating electrons and in a second mode for regenerating said photocathode.  
     
     
         22 . A controller in accordance with  claim 21 , said photocathode comprising a cesium telluride photocathode.  
     
     
         23 . A controller according to  claim 21 , wherein said controller is adapted to control application of said at least one laser in said first mode, such that said at least one laser is applied at a power density of approximately 10 4  Watts per square centimeter.  
     
     
         24 . A controller in accordance with  claim 21 , wherein said controller is adapted to control application of said at least one laser in said second mode, such that said at least one laser is applied at a power density in the range substantially comprising 10 4 -10 6  Watts per square centimeter.  
     
     
         25 . A controller in accordance with  claim 21 , wherein said controller is adapted to control application of said at least one laser in said second mode, such that said at least one laser is applied to raise a temperature of said cesium telluride photocathode in the range substantially comprising 20-200 C above room temperature.