Electron Microscope And Electron Beam Inspection System

Abstract

An electron microscope includes an electron source, a stage for mounting a specimen, an illuminating lens system that illuminates an electron beam onto the specimen, an imaging lens system that forms a specimen image using a reflecting electron beam of the illuminating electron beam, a beam separator that separates the illuminating electron beam and the reflecting electron beam, a control unit that controls current to be supplied to the beam separator; and a switching unit which enables switching between a first mode and a second mode. The control unit changes a value of the current to be supplied to the beam separator when switching from the first mode to the second mode.

1 . An electron microscope, comprising:
 an electron source;   a stage for mounting a specimen;   an illuminating lens system that illuminates an electron beam that is emitted from the electron source onto a specimen which is mounted on the stage;   an imaging lens system that forms a specimen image using a reflecting electron beam of the illuminating electron beam;   a beam separator that separates the illuminating electron beam and the reflecting electron beam;   a control unit that controls current to be supplied to the beam separator; and   means for switching between a first mode and a second mode;   wherein in the first mode, the reflecting electron beam comprises electrons returned back in a vicinity of a surface of the specimen without colliding with the specimen;   wherein in the second mode, the reflecting electron beam comprises secondary electrons generated from the specimen or backscattered electrons; and   wherein the control unit changes a value of the current to be supplied to the beam separator when switching from the first mode to the second mode.   
   
   
       2 . The electron microscope according to  claim 1 , wherein the control unit also controls the voltage to be supplied to the beam separator, and wherein the control unit changes a value of the voltage to be supplied to the beam separator when switching from the first mode to the second mode. 
   
   
       3 . The electron microscope, according to  claim 1 , wherein the control unit also controls current to be supplied to the illuminating lens system and the imaging lens system, and
 wherein the control unit changes a value of the current to be supplied to the illuminating lens system and the imaging lens system when switching from the first mode to the second mode.   
   
   
       4 . The electron microscope, according to  claim 1 , wherein the beam separator is an E×B deflector. 
   
   
       5 . The electron microscope, according to  claim 1 , wherein the control unit operates such that a focal length of the imaging lens system is kept constant when switching from the first mode to the second mode. 
   
   
       6 . The electron microscope according to  claim 1 , wherein a magnification to observe a visual field in the first mode and a magnification to observe a visual field in the second mode are a same magnification when switching from the first mode to the second mode. 
   
   
       7 . An electron microscope comprising:
 an electron source;   a stage for mounting a specimen;   an illuminating lens system that illuminates an electron beam that is emitted from the electron source onto a specimen which is mounted on the stage;   an imaging lens system that forms a specimen image using a reflecting electron beam of the illuminating electron beam;   a beam separator that separates the illuminating electron beam and the reflecting electron beam;   a control unit that controls current to be supplied to the beam separator; and   means for switching between a first mode and a second mode;   wherein in the first mode, the reflecting electron beam comprises electrons returned back in a vicinity of a surface of the specimen without colliding with the specimen;   wherein in the second mode, the reflecting electron beam is comprises secondary electrons generated from the specimen or backscattered electrons;   wherein the illuminating lens system comprises a deflector; and   wherein the deflector operates so that a deflection angle of the reflecting electron beam caused by the beam separator is returned to an original deflection angle when switching from the first mode to the second mode.   
   
   
       8 . The electron microscope according to  claim 7 , wherein an operating condition of the beam separator is not changed when switching from the first mode to the second mode. 
   
   
       9 . The electron microscope according to  claim 7 , wherein the beam separator is an E×B deflector.