Method of etching materials with electron beam and laser energy

Abstract

We disclose a method of electron-beam induced of etching the surface of a specimen in a charged-particle beam instrument, where the charged-particle beam instrument has first and second laser beams, an electron beam, and a gas-injection system for applying etchant gas to the surface. Etching is accomplished by applying a photolytic pulse from the first laser to the surface; applying a pyrolytic pulse from the second laser to the surface; and, applying an etchant gas to the surface at least during the pyrolytic pulse. Two or more alternating pyrolytic laser pulses and photolytic laser pulses may be applied to the surface. The stage supporting the specimen may be tilted relative to the axis of the electron beam before applying the electron beam to the surface of the specimen. The electron beam is applied to the surface of the specimen during the time the etchant gas is present at the surface.

1 . A method of etching the surface of a specimen in a charged-particle beam instrument, where the charged-particle beam instrument has first and second laser beams, an electron beam, and a gas-injection system for applying etchant gas to the surface, the method comprising:
 applying a photolytic pulse from the first laser to the surface;   applying a pyrolytic pulse from the second laser to the surface; and, applying an etchant gas to the surface at least during the pyrolytic pulse.   
     
     
         2 . The method of  claim 1 , comprising two or more alternating pyrolytic laser pulses and photolytic laser pulses. 
     
     
         3 . The method of  claim 1 , further comprising:
 imaging the surface after the application of the etchant gas to determine if the etching of the surface is completed; and,
 if the etching of the surface is not completed, then, repeating the application of the photolytic laser pulse, the pyrolytic laser pulse and the application of the etchant gas. 
   
     
     
         4 . The method of  claim 1 , further comprising:
 applying the electron beam to the surface of the specimen during the application of the etchant gas.   
     
     
         5 . The method of  claim 4 , where the charged-particle beam instrument further comprises a stage supporting the specimen, the method further comprising:
 tilting the stage supporting the specimen relative to the axis of the electron beam before applying the electron beam to the surface of the specimen; and,   applying the electron beam to the surface of the specimen during the time the etchant gas is present at the surface.   
     
     
         6 . The method of  claim 5 , where the energy of the electron beam is selected to substantially maximize secondary electron emission from the surface. 
     
     
         7 . The method of  claim 1 , where the charged-particle beam instrument further comprises a stage supporting the specimen, the method further comprising:
 applying the electron beam to the surface of the specimen both during the time the etchant gas is present at the surface and during the time the pyrolytic laser beam is applied to the surface.   
     
     
         8 . The method of  claim 7 , further comprising:
 tilting the stage supporting the specimen relative to the axis of the electron beam before applying the electron beam to the surface of the specimen; and,   applying the electron beam to the surface of the specimen during the time the etchant gas is present at the surface.   
     
     
         9 . The method of  claim 8 , where the energy of the electron beam is selected to substantially maximize secondary electron emission from the surface. 
     
     
         10 . A method of etching the surface of a specimen in a charged-particle beam instrument, where the charged-particle beam instrument has a stage supporting the specimen, an electron beam, a pyrolytic laser beam, and a gas-injection system for applying etchant gas to the surface, the method comprising:
 tilting the stage supporting the specimen relative to the axis of the electron beam;   applying the etchant gas to the surface; and,   applying the pyrolytic laser beam to the surface; and,   applying the electron beam to the surface of the specimen during the time the etchant gas is present at the surface and during the time the pyrolytic laser beam is applied to the surface.   
     
     
         11 . The method of  claim 10 , where the energy of the electron beam is selected to substantially maximize secondary electron emission from the surface.