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Charged-particle beam apparatus and method for automatically correcting astigmatism and for height detection

  • US 20060060781A1
  • Filed: 04/26/2005
  • Published: 03/23/2006
  • Est. Priority Date: 08/11/1997
  • Status: Abandoned Application
First Claim
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1. A charged-particle beam apparatus comprising:

  • a stage on which a sample is set;

    a charged-particle optical system for converging a charged-particle beam generated by a charged-particle source;

    a scanning means for scanning an area on said sample in which a pattern is formed with said charged-particle beam converged by said charged-particle optical system;

    a focus control means for controlling a focal position of said charged-particle beam converged by said charged-particle optical system;

    an astigmatism adjustment means for adjusting astigmatism of said charged-particle beam converged by said charged-particle optical system;

    an image detection means for obtaining an image of said sample by detecting secondary particles generated from said sample by the scanning of said converged charged-particle beam by said scanning means;

    an image-processing means for processing said image obtained by said image detection means; and

    a control system for adjusting and controlling said astigmatism of said converged charged-particle beam by using information from said image-processing means, wherein, said control system so controls that said scanning means scans said charged particle bean in one direction, said image detection means obtains plural images of said sample having mutually different focal positions by changing focal position of said charged particle beam with said focus control means, said image processing means computes sharpness values of said charged-particle optical system in two directions which are substantially perpendicular with each other, said scanning means changes scanning direction in another direction inclined to said one direction and scanning said area on said sample in a direction inclined to that of the previous scanning of said area, said image detection means obtains plural images of said sample having mutually different focal positions by changing focal position of said charged particle beam with said focus control means, said image processing means computes sharpness values of said charged-particle optical system in two directions which are substantially perpendicular with each other, calculating astigmatism of said charged-particle optical system based on said computed sharpness value in four directions of said converged charged-particle beam and feeding back an astigmatism correction amount to said astigmatism adjustment means based on said calculated astigmatism.

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