Charged particle beam apparatus

Abstract

A charged particle beam apparatus is provided which has high resolving power and a wide scanning region (observation field of view). The apparatus has a unit for adjusting the focus, a unit for adjusting astigmatism, a unit for controlling and detecting scanning positions and a controller operative to control the focus adjustment and astigmatism adjustment at a time in interlocked relation to the scanning positions, thereby assuring compatibility between the high resolving power and the observation view field of a wide area.

1 . A charged particle beam apparatus comprising: 
 a charged particle beam source;    a lens system including an objective lens for focusing a charged particle beam emitted from said charged particle beam source on a specimen;    deflection control means for scanning the charged particle beam on the specimen;    focus adjustment means for adjusting a focal position of the charged particle beam by controlling said objective lens;    astigmatism adjustment means for adjusting astigmatism of the charged particle beam;    memory means for storing the relation among a deflection position or deflection angle of the charged particle beam by said deflection control means, a focus adjustment value by said focus adjustment means and an astigmatism adjustment value by said astigmatism adjustment means; and    a controller for controlling said deflection control means, focus adjustment means and astigmatism adjustment means,    wherein said controller operates in interlocked relation to the deflection position or deflection angle of said charged particle beam by said deflection control means to control said focus control means such that said charged particle beam is focused on said specimen in accordance with the relation stored in said memory means and to cause said astigmatism adjustment means to correct said charged particle beam for an astigmatic aberration.    
   
   
       2 . A charged particle beam apparatus according to  claim 1 , wherein said focus adjustment means controls an electrostatic lens.  
   
   
       3 . A charged particle beam apparatus according to  claim 1 , wherein said focus adjustment means controls an electromagnetic lens.  
   
   
       4 . A charged particle beam apparatus according to  claim 1 , wherein said astigmatism adjustment means controls an electrostatic type stigmator.  
   
   
       5 . A charged particle beam apparatus according to  claim 1 , wherein said astigmatism adjustment means controls an electromagnetic type stigmator.  
   
   
       6 . A charged particle beam apparatus according to  claim 3 , wherein said objective lens includes a first coil as a main part and a second coil for focus correction and said focus adjustment means controls said second coil.  
   
   
       7 . A charged particle beam apparatus according to  claim 1 , wherein said objective lens includes an electromagnetic lens and a focus correction electrode and said focus adjustment means controls said focus correction electrode.  
   
   
       8 . A charged particle beam apparatus according to  claim 1  further comprising electromagnetic type deflection means, wherein said deflection control means controls the value of a current passed through said electromagnetic type deflection means.  
   
   
       9 . A charged particle beam apparatus according to  claim 1  further comprising electrostatic type deflection means, wherein said deflection control means controls the value of a voltage applied to said electrostatic type deflection means.  
   
   
       10 . A charged particle beams apparatus according to  claim 9 , wherein a voltage value for astigmatism adjustment by said astigmatism adjustment control means is applied to said electrostatic type deflection means in a superimposed fashion.  
   
   
       11 . A charged particle beam apparatus according to  claim 1 , wherein said deflection control means corrects a scan distortion occurring at a peripheral portion of a scanning region in accordance with the relation between a deflection position or deflection angle stored in said memory means and an amount of control by said deflector.  
   
   
       12 . A charged particle beam apparatus according to  claim 1  further comprising a detector for detecting a signal generated from the specimen under irradiation of said charged particle beam and display means for displaying a specimen image by using an output of said detector.  
   
   
       13 . A charged particle beam apparatus according to  claim 1 , wherein a scanning region of said charged particle beam is divided into a plurality of areas and adjustment values of said focus adjustment means adjusted at the individual areas and adjustment values of said astigmatism adjustment means adjusted at the individual areas are stored in said memory means by making the correspondence with positions of said areas.  
   
   
       14 . A charged particle beam apparatus according to  claim 13 , wherein the adjusted values of said focus adjustment means and the adjusted values of said astigmatism adjustment means are stored as a functional expression of deflection position or deflection angle of said charged particle beam.  
   
   
       15 . A charged particle beam apparatus according to  claim 13  further comprising a detector for detecting a signal generated from the specimen under irradiation of said charged particle beam and display means, wherein 
 said display means has an area for displaying a specimen image by using an output of said detector, an area for displaying adjusted values of said focus adjustment means and adjusted valued of said astigmatism adjustment means and an area for diagrammatically displaying said divided areas.    
   
   
       16 . A charged particle beam apparatus according to  claim 14  further comprising a detector for detecting a signal generated from the specimen under irradiation of said charged particle beam and display means, wherein 
 said display means has an area for displaying a specimen image by using an output of said detector and an area for displaying adjusted values of said focus adjustment means, adjusted values of said astigmatism adjustment means and said functional expression.    
   
   
       17 . A charged particle beam apparatus comprising: 
 a charged particle beam source;    a lens system including an objective lens for focusing a charged particle beam emitted from said charged particle beam source on a specimen;    deflection control means for scanning said charged particle beam on the specimen;    a detector for detecting a signal generated from the specimen under irradiation of said charged particle beam;    memory means for storing an output signal from said detector as an image signal;    image comparison means for performing image comparison on the basis of said image signal;    decision means for deciding the presence or absence of a defect of the specimen on the basis of a result of comparison by said image comparison means;    focus adjustment means for adjusting a focal position of said charged particle beam by controlling said objective lens;    astigmatism adjustment means for adjusting astigmatism of said charged particle beam;    memory means for storing the relation among a deflection position or deflection angle of said charged particle beam by said deflection control means, a focus adjustment value by said focus adjustment means and an astigmatism adjustment value by said astigmatism adjustment means; and    a controller for controlling said deflection control means, focus adjustment means and astigmatism adjustment means,    wherein said controller operates in interlocked relation to the deflection position or deflection angle of said charged particle beam by said deflection control means to control said focus control means such that said charged particle beam is focused on said specimen in accordance with the relation stored in said memory means and to cause said astigmatism adjustment means to correct said charged particle beam for an astigmatic aberration.