Charged particle beam apparatus and automatic astigmatism adjustment method

A method for detecting an image of a sample, comprising:

• setting a specimen on a table on which a sample is mounted and said table is movable at least in one direction;
• converging a charged particle beam emitted from a charged particle source;
• irradiating and scanning said converged charged particle beam onto a surface of said sample mounted on said stage;
• detecting a plurality of images of said sample by detecting particles generated from said sample by the irradiation and scanning of said converged charged particle beam by changing focal positions of said converged charged particle beam;
• computing an astigmatism correction quantity and a focal point correction quantity based on a focal offset and astigmatism of said converged charged particle beam obtained by processing said plurality of detected images;
• adjusting said astigmatism of said converged charged particle beam based on said computed astigmatism correction quantity;
• adjusting said focal point of said converged charged particle beam based on said computed focal point correction quantity;
• irradiating and scanning said converged charged particle beam onto a surface of said specimen set on said stage;
• optically detecting a height of the surface of said specimen which is moving at least in one direction by the movement of said table and irradiated and scanned by said converged charged particle beam;
• controlling said focal point of said converged charged particle beam based on said computed focal point correction quantity and said optically detected height of the surface of said specimen on which said converged charged particle beam is irradiated and scanned;
• and
• continuously detecting images of said specimen by the irradiation and scanning of said converged charged particle beam the focal point of which is controlled by the step of said controlling while said sample is moving at least in one direction by the movement.of said table.

A method for detecting an image of a sample, comprising:

• setting a specimen on a table on which a sample is mounted and said table is movable at least in one direction;
• irradiating and scanning a converged electron beam onto a surface of said specimen mounted on said stage;
• optically detecting a height of the surface of said specimen which is irradiated and scanned by said converged electron beam;
• controlling said focal point of said converged electron beam using information of optically detected height of the surface of said specimen;
• and
• detecting a secondary electron generated from said specimen by the irradiation and scanning of the converged electron beam,
• wherein a focal offset and an astigmatism of said converged electron beam is controlled based on a focal offset correction quantity and an astigmatism correction quantity computed from plural secondary electron images formed by detecting a secondary electron generated by irradiating and scanning said converged electron beam on said sample mounted on said stage by changing focal positions of said electron beam.