Patent ID: 6838667
Filing Date: 2005-01-04
Classification: H01J

Abstract:
1. An apparatus for charged particle beam microscopy comprising: a recording unit for recording a first charged particle beam image obtained when a focus of a lens for charged particle beam on a specimen is located in a first position and a second charged particle beam image obtained when said focus is located in a second position; a calculation unit for analyzing a positional displacement between said first and second charged particle beam images and a degree of coincidence indicating a degree of resemblance between said first and second charged particle beam images; a judgment unit for judging from said degree of coincidence whether said positional displacement can be converted into an axial displacement of a primary charged particle beam relative to said lens for charged particle beam; and an alignment unit for correcting said axial displacement of said primary charged particle beam relative to said lens for charged particle beam in response to an alignment signal calculated from said positional displacement, wherein said calculation unit calculates the degree of coincidence by calculating a Fourier transformation of said first and second charged particle beam images, calculating a phase difference of said Fourier transformed first and second charged particle beam images, calculating an inverse Fourier transform of said phase difference, and calculating the degree of coincidence defined as an intensity of a δ peak appearing in said inverse Fourier transformed phase difference.