Auto focusing apparatus of scanning electron microscopes
AssigneeHitachi, Ltd.
InventorTatsuya Maeda
Life of this patent
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Abstract
An auto focusing apparatus of a scanning electron microscope includes an auto focusing mechanism which calculates a focus evaluation value, using an electron signal or picture signal generated from a specimen when the specimen is scanned by an electron beam focused by an objective lens, and controls an exciting current of the objective lens according to said focus evaluation value. A focus correction value register and a focus correction mechanism for correcting the focused position determined by the aforementioned auto focusing mechanism by as much as the correction value registered in the focus correction value register are provided.
Claims8
An auto focusing apparatus of a scanning electron microscope comprising:
- an auto focusing mechanism;
- an objective lens;
- a focus correction value register;
- and
- a focus correction mechanism;
- wherein said auto focusing mechanism calculates a focus evaluation value, using an electron signal generated from a specimen when the specimen is scanned by an electron beam focused by said objective lens, and controls an exciting current of the objective lens according to said focus evaluation value;
- and
- said focus correction mechanism corrects a focused position determined by said auto focusing mechanism by as much as a focus correction value registered in the focus correction value register.
An auto focusing apparatus of a scanning electron microscope comprising:
- an auto focusing mechanism;
- an objective lens;
- a focus correction value register;
- and
- a focus correction mechanism;
- wherein said auto focusing mechanism calculates a focus evaluation value, using a picture signal generated from a specimen when the specimen is scanned by an electron beam focused by said objective lens, and controls an exciting current of the objective lens, according to said focus evaluation value;
- and
- wherein said focus correction mechanism corrects a focused position determined by said auto focusing mechanism by as much as a focus correction value registered in the locus correction value register.
Dependencies are inferred from the claim text.